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TOMOYO Linux Cross Reference
Linux/fs/xfs/xfs_log.c

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  1 /*
  2  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
  3  * All Rights Reserved.
  4  *
  5  * This program is free software; you can redistribute it and/or
  6  * modify it under the terms of the GNU General Public License as
  7  * published by the Free Software Foundation.
  8  *
  9  * This program is distributed in the hope that it would be useful,
 10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12  * GNU General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, write the Free Software Foundation,
 16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 17  */
 18 #include "xfs.h"
 19 #include "xfs_fs.h"
 20 #include "xfs_types.h"
 21 #include "xfs_log.h"
 22 #include "xfs_trans.h"
 23 #include "xfs_sb.h"
 24 #include "xfs_ag.h"
 25 #include "xfs_mount.h"
 26 #include "xfs_error.h"
 27 #include "xfs_log_priv.h"
 28 #include "xfs_buf_item.h"
 29 #include "xfs_bmap_btree.h"
 30 #include "xfs_alloc_btree.h"
 31 #include "xfs_ialloc_btree.h"
 32 #include "xfs_log_recover.h"
 33 #include "xfs_trans_priv.h"
 34 #include "xfs_dinode.h"
 35 #include "xfs_inode.h"
 36 #include "xfs_trace.h"
 37 
 38 kmem_zone_t     *xfs_log_ticket_zone;
 39 
 40 /* Local miscellaneous function prototypes */
 41 STATIC int
 42 xlog_commit_record(
 43         struct xlog             *log,
 44         struct xlog_ticket      *ticket,
 45         struct xlog_in_core     **iclog,
 46         xfs_lsn_t               *commitlsnp);
 47 
 48 STATIC struct xlog *
 49 xlog_alloc_log(
 50         struct xfs_mount        *mp,
 51         struct xfs_buftarg      *log_target,
 52         xfs_daddr_t             blk_offset,
 53         int                     num_bblks);
 54 STATIC int
 55 xlog_space_left(
 56         struct xlog             *log,
 57         atomic64_t              *head);
 58 STATIC int
 59 xlog_sync(
 60         struct xlog             *log,
 61         struct xlog_in_core     *iclog);
 62 STATIC void
 63 xlog_dealloc_log(
 64         struct xlog             *log);
 65 
 66 /* local state machine functions */
 67 STATIC void xlog_state_done_syncing(xlog_in_core_t *iclog, int);
 68 STATIC void
 69 xlog_state_do_callback(
 70         struct xlog             *log,
 71         int                     aborted,
 72         struct xlog_in_core     *iclog);
 73 STATIC int
 74 xlog_state_get_iclog_space(
 75         struct xlog             *log,
 76         int                     len,
 77         struct xlog_in_core     **iclog,
 78         struct xlog_ticket      *ticket,
 79         int                     *continued_write,
 80         int                     *logoffsetp);
 81 STATIC int
 82 xlog_state_release_iclog(
 83         struct xlog             *log,
 84         struct xlog_in_core     *iclog);
 85 STATIC void
 86 xlog_state_switch_iclogs(
 87         struct xlog             *log,
 88         struct xlog_in_core     *iclog,
 89         int                     eventual_size);
 90 STATIC void
 91 xlog_state_want_sync(
 92         struct xlog             *log,
 93         struct xlog_in_core     *iclog);
 94 
 95 STATIC void
 96 xlog_grant_push_ail(
 97         struct xlog             *log,
 98         int                     need_bytes);
 99 STATIC void
100 xlog_regrant_reserve_log_space(
101         struct xlog             *log,
102         struct xlog_ticket      *ticket);
103 STATIC void
104 xlog_ungrant_log_space(
105         struct xlog             *log,
106         struct xlog_ticket      *ticket);
107 
108 #if defined(DEBUG)
109 STATIC void
110 xlog_verify_dest_ptr(
111         struct xlog             *log,
112         char                    *ptr);
113 STATIC void
114 xlog_verify_grant_tail(
115         struct xlog *log);
116 STATIC void
117 xlog_verify_iclog(
118         struct xlog             *log,
119         struct xlog_in_core     *iclog,
120         int                     count,
121         boolean_t               syncing);
122 STATIC void
123 xlog_verify_tail_lsn(
124         struct xlog             *log,
125         struct xlog_in_core     *iclog,
126         xfs_lsn_t               tail_lsn);
127 #else
128 #define xlog_verify_dest_ptr(a,b)
129 #define xlog_verify_grant_tail(a)
130 #define xlog_verify_iclog(a,b,c,d)
131 #define xlog_verify_tail_lsn(a,b,c)
132 #endif
133 
134 STATIC int
135 xlog_iclogs_empty(
136         struct xlog             *log);
137 
138 static void
139 xlog_grant_sub_space(
140         struct xlog             *log,
141         atomic64_t              *head,
142         int                     bytes)
143 {
144         int64_t head_val = atomic64_read(head);
145         int64_t new, old;
146 
147         do {
148                 int     cycle, space;
149 
150                 xlog_crack_grant_head_val(head_val, &cycle, &space);
151 
152                 space -= bytes;
153                 if (space < 0) {
154                         space += log->l_logsize;
155                         cycle--;
156                 }
157 
158                 old = head_val;
159                 new = xlog_assign_grant_head_val(cycle, space);
160                 head_val = atomic64_cmpxchg(head, old, new);
161         } while (head_val != old);
162 }
163 
164 static void
165 xlog_grant_add_space(
166         struct xlog             *log,
167         atomic64_t              *head,
168         int                     bytes)
169 {
170         int64_t head_val = atomic64_read(head);
171         int64_t new, old;
172 
173         do {
174                 int             tmp;
175                 int             cycle, space;
176 
177                 xlog_crack_grant_head_val(head_val, &cycle, &space);
178 
179                 tmp = log->l_logsize - space;
180                 if (tmp > bytes)
181                         space += bytes;
182                 else {
183                         space = bytes - tmp;
184                         cycle++;
185                 }
186 
187                 old = head_val;
188                 new = xlog_assign_grant_head_val(cycle, space);
189                 head_val = atomic64_cmpxchg(head, old, new);
190         } while (head_val != old);
191 }
192 
193 STATIC void
194 xlog_grant_head_init(
195         struct xlog_grant_head  *head)
196 {
197         xlog_assign_grant_head(&head->grant, 1, 0);
198         INIT_LIST_HEAD(&head->waiters);
199         spin_lock_init(&head->lock);
200 }
201 
202 STATIC void
203 xlog_grant_head_wake_all(
204         struct xlog_grant_head  *head)
205 {
206         struct xlog_ticket      *tic;
207 
208         spin_lock(&head->lock);
209         list_for_each_entry(tic, &head->waiters, t_queue)
210                 wake_up_process(tic->t_task);
211         spin_unlock(&head->lock);
212 }
213 
214 static inline int
215 xlog_ticket_reservation(
216         struct xlog             *log,
217         struct xlog_grant_head  *head,
218         struct xlog_ticket      *tic)
219 {
220         if (head == &log->l_write_head) {
221                 ASSERT(tic->t_flags & XLOG_TIC_PERM_RESERV);
222                 return tic->t_unit_res;
223         } else {
224                 if (tic->t_flags & XLOG_TIC_PERM_RESERV)
225                         return tic->t_unit_res * tic->t_cnt;
226                 else
227                         return tic->t_unit_res;
228         }
229 }
230 
231 STATIC bool
232 xlog_grant_head_wake(
233         struct xlog             *log,
234         struct xlog_grant_head  *head,
235         int                     *free_bytes)
236 {
237         struct xlog_ticket      *tic;
238         int                     need_bytes;
239 
240         list_for_each_entry(tic, &head->waiters, t_queue) {
241                 need_bytes = xlog_ticket_reservation(log, head, tic);
242                 if (*free_bytes < need_bytes)
243                         return false;
244 
245                 *free_bytes -= need_bytes;
246                 trace_xfs_log_grant_wake_up(log, tic);
247                 wake_up_process(tic->t_task);
248         }
249 
250         return true;
251 }
252 
253 STATIC int
254 xlog_grant_head_wait(
255         struct xlog             *log,
256         struct xlog_grant_head  *head,
257         struct xlog_ticket      *tic,
258         int                     need_bytes)
259 {
260         list_add_tail(&tic->t_queue, &head->waiters);
261 
262         do {
263                 if (XLOG_FORCED_SHUTDOWN(log))
264                         goto shutdown;
265                 xlog_grant_push_ail(log, need_bytes);
266 
267                 __set_current_state(TASK_UNINTERRUPTIBLE);
268                 spin_unlock(&head->lock);
269 
270                 XFS_STATS_INC(xs_sleep_logspace);
271 
272                 trace_xfs_log_grant_sleep(log, tic);
273                 schedule();
274                 trace_xfs_log_grant_wake(log, tic);
275 
276                 spin_lock(&head->lock);
277                 if (XLOG_FORCED_SHUTDOWN(log))
278                         goto shutdown;
279         } while (xlog_space_left(log, &head->grant) < need_bytes);
280 
281         list_del_init(&tic->t_queue);
282         return 0;
283 shutdown:
284         list_del_init(&tic->t_queue);
285         return XFS_ERROR(EIO);
286 }
287 
288 /*
289  * Atomically get the log space required for a log ticket.
290  *
291  * Once a ticket gets put onto head->waiters, it will only return after the
292  * needed reservation is satisfied.
293  *
294  * This function is structured so that it has a lock free fast path. This is
295  * necessary because every new transaction reservation will come through this
296  * path. Hence any lock will be globally hot if we take it unconditionally on
297  * every pass.
298  *
299  * As tickets are only ever moved on and off head->waiters under head->lock, we
300  * only need to take that lock if we are going to add the ticket to the queue
301  * and sleep. We can avoid taking the lock if the ticket was never added to
302  * head->waiters because the t_queue list head will be empty and we hold the
303  * only reference to it so it can safely be checked unlocked.
304  */
305 STATIC int
306 xlog_grant_head_check(
307         struct xlog             *log,
308         struct xlog_grant_head  *head,
309         struct xlog_ticket      *tic,
310         int                     *need_bytes)
311 {
312         int                     free_bytes;
313         int                     error = 0;
314 
315         ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
316 
317         /*
318          * If there are other waiters on the queue then give them a chance at
319          * logspace before us.  Wake up the first waiters, if we do not wake
320          * up all the waiters then go to sleep waiting for more free space,
321          * otherwise try to get some space for this transaction.
322          */
323         *need_bytes = xlog_ticket_reservation(log, head, tic);
324         free_bytes = xlog_space_left(log, &head->grant);
325         if (!list_empty_careful(&head->waiters)) {
326                 spin_lock(&head->lock);
327                 if (!xlog_grant_head_wake(log, head, &free_bytes) ||
328                     free_bytes < *need_bytes) {
329                         error = xlog_grant_head_wait(log, head, tic,
330                                                      *need_bytes);
331                 }
332                 spin_unlock(&head->lock);
333         } else if (free_bytes < *need_bytes) {
334                 spin_lock(&head->lock);
335                 error = xlog_grant_head_wait(log, head, tic, *need_bytes);
336                 spin_unlock(&head->lock);
337         }
338 
339         return error;
340 }
341 
342 static void
343 xlog_tic_reset_res(xlog_ticket_t *tic)
344 {
345         tic->t_res_num = 0;
346         tic->t_res_arr_sum = 0;
347         tic->t_res_num_ophdrs = 0;
348 }
349 
350 static void
351 xlog_tic_add_region(xlog_ticket_t *tic, uint len, uint type)
352 {
353         if (tic->t_res_num == XLOG_TIC_LEN_MAX) {
354                 /* add to overflow and start again */
355                 tic->t_res_o_flow += tic->t_res_arr_sum;
356                 tic->t_res_num = 0;
357                 tic->t_res_arr_sum = 0;
358         }
359 
360         tic->t_res_arr[tic->t_res_num].r_len = len;
361         tic->t_res_arr[tic->t_res_num].r_type = type;
362         tic->t_res_arr_sum += len;
363         tic->t_res_num++;
364 }
365 
366 /*
367  * Replenish the byte reservation required by moving the grant write head.
368  */
369 int
370 xfs_log_regrant(
371         struct xfs_mount        *mp,
372         struct xlog_ticket      *tic)
373 {
374         struct xlog             *log = mp->m_log;
375         int                     need_bytes;
376         int                     error = 0;
377 
378         if (XLOG_FORCED_SHUTDOWN(log))
379                 return XFS_ERROR(EIO);
380 
381         XFS_STATS_INC(xs_try_logspace);
382 
383         /*
384          * This is a new transaction on the ticket, so we need to change the
385          * transaction ID so that the next transaction has a different TID in
386          * the log. Just add one to the existing tid so that we can see chains
387          * of rolling transactions in the log easily.
388          */
389         tic->t_tid++;
390 
391         xlog_grant_push_ail(log, tic->t_unit_res);
392 
393         tic->t_curr_res = tic->t_unit_res;
394         xlog_tic_reset_res(tic);
395 
396         if (tic->t_cnt > 0)
397                 return 0;
398 
399         trace_xfs_log_regrant(log, tic);
400 
401         error = xlog_grant_head_check(log, &log->l_write_head, tic,
402                                       &need_bytes);
403         if (error)
404                 goto out_error;
405 
406         xlog_grant_add_space(log, &log->l_write_head.grant, need_bytes);
407         trace_xfs_log_regrant_exit(log, tic);
408         xlog_verify_grant_tail(log);
409         return 0;
410 
411 out_error:
412         /*
413          * If we are failing, make sure the ticket doesn't have any current
414          * reservations.  We don't want to add this back when the ticket/
415          * transaction gets cancelled.
416          */
417         tic->t_curr_res = 0;
418         tic->t_cnt = 0; /* ungrant will give back unit_res * t_cnt. */
419         return error;
420 }
421 
422 /*
423  * Reserve log space and return a ticket corresponding the reservation.
424  *
425  * Each reservation is going to reserve extra space for a log record header.
426  * When writes happen to the on-disk log, we don't subtract the length of the
427  * log record header from any reservation.  By wasting space in each
428  * reservation, we prevent over allocation problems.
429  */
430 int
431 xfs_log_reserve(
432         struct xfs_mount        *mp,
433         int                     unit_bytes,
434         int                     cnt,
435         struct xlog_ticket      **ticp,
436         __uint8_t               client,
437         bool                    permanent,
438         uint                    t_type)
439 {
440         struct xlog             *log = mp->m_log;
441         struct xlog_ticket      *tic;
442         int                     need_bytes;
443         int                     error = 0;
444 
445         ASSERT(client == XFS_TRANSACTION || client == XFS_LOG);
446 
447         if (XLOG_FORCED_SHUTDOWN(log))
448                 return XFS_ERROR(EIO);
449 
450         XFS_STATS_INC(xs_try_logspace);
451 
452         ASSERT(*ticp == NULL);
453         tic = xlog_ticket_alloc(log, unit_bytes, cnt, client, permanent,
454                                 KM_SLEEP | KM_MAYFAIL);
455         if (!tic)
456                 return XFS_ERROR(ENOMEM);
457 
458         tic->t_trans_type = t_type;
459         *ticp = tic;
460 
461         xlog_grant_push_ail(log, tic->t_cnt ? tic->t_unit_res * tic->t_cnt
462                                             : tic->t_unit_res);
463 
464         trace_xfs_log_reserve(log, tic);
465 
466         error = xlog_grant_head_check(log, &log->l_reserve_head, tic,
467                                       &need_bytes);
468         if (error)
469                 goto out_error;
470 
471         xlog_grant_add_space(log, &log->l_reserve_head.grant, need_bytes);
472         xlog_grant_add_space(log, &log->l_write_head.grant, need_bytes);
473         trace_xfs_log_reserve_exit(log, tic);
474         xlog_verify_grant_tail(log);
475         return 0;
476 
477 out_error:
478         /*
479          * If we are failing, make sure the ticket doesn't have any current
480          * reservations.  We don't want to add this back when the ticket/
481          * transaction gets cancelled.
482          */
483         tic->t_curr_res = 0;
484         tic->t_cnt = 0; /* ungrant will give back unit_res * t_cnt. */
485         return error;
486 }
487 
488 
489 /*
490  * NOTES:
491  *
492  *      1. currblock field gets updated at startup and after in-core logs
493  *              marked as with WANT_SYNC.
494  */
495 
496 /*
497  * This routine is called when a user of a log manager ticket is done with
498  * the reservation.  If the ticket was ever used, then a commit record for
499  * the associated transaction is written out as a log operation header with
500  * no data.  The flag XLOG_TIC_INITED is set when the first write occurs with
501  * a given ticket.  If the ticket was one with a permanent reservation, then
502  * a few operations are done differently.  Permanent reservation tickets by
503  * default don't release the reservation.  They just commit the current
504  * transaction with the belief that the reservation is still needed.  A flag
505  * must be passed in before permanent reservations are actually released.
506  * When these type of tickets are not released, they need to be set into
507  * the inited state again.  By doing this, a start record will be written
508  * out when the next write occurs.
509  */
510 xfs_lsn_t
511 xfs_log_done(
512         struct xfs_mount        *mp,
513         struct xlog_ticket      *ticket,
514         struct xlog_in_core     **iclog,
515         uint                    flags)
516 {
517         struct xlog             *log = mp->m_log;
518         xfs_lsn_t               lsn = 0;
519 
520         if (XLOG_FORCED_SHUTDOWN(log) ||
521             /*
522              * If nothing was ever written, don't write out commit record.
523              * If we get an error, just continue and give back the log ticket.
524              */
525             (((ticket->t_flags & XLOG_TIC_INITED) == 0) &&
526              (xlog_commit_record(log, ticket, iclog, &lsn)))) {
527                 lsn = (xfs_lsn_t) -1;
528                 if (ticket->t_flags & XLOG_TIC_PERM_RESERV) {
529                         flags |= XFS_LOG_REL_PERM_RESERV;
530                 }
531         }
532 
533 
534         if ((ticket->t_flags & XLOG_TIC_PERM_RESERV) == 0 ||
535             (flags & XFS_LOG_REL_PERM_RESERV)) {
536                 trace_xfs_log_done_nonperm(log, ticket);
537 
538                 /*
539                  * Release ticket if not permanent reservation or a specific
540                  * request has been made to release a permanent reservation.
541                  */
542                 xlog_ungrant_log_space(log, ticket);
543                 xfs_log_ticket_put(ticket);
544         } else {
545                 trace_xfs_log_done_perm(log, ticket);
546 
547                 xlog_regrant_reserve_log_space(log, ticket);
548                 /* If this ticket was a permanent reservation and we aren't
549                  * trying to release it, reset the inited flags; so next time
550                  * we write, a start record will be written out.
551                  */
552                 ticket->t_flags |= XLOG_TIC_INITED;
553         }
554 
555         return lsn;
556 }
557 
558 /*
559  * Attaches a new iclog I/O completion callback routine during
560  * transaction commit.  If the log is in error state, a non-zero
561  * return code is handed back and the caller is responsible for
562  * executing the callback at an appropriate time.
563  */
564 int
565 xfs_log_notify(
566         struct xfs_mount        *mp,
567         struct xlog_in_core     *iclog,
568         xfs_log_callback_t      *cb)
569 {
570         int     abortflg;
571 
572         spin_lock(&iclog->ic_callback_lock);
573         abortflg = (iclog->ic_state & XLOG_STATE_IOERROR);
574         if (!abortflg) {
575                 ASSERT_ALWAYS((iclog->ic_state == XLOG_STATE_ACTIVE) ||
576                               (iclog->ic_state == XLOG_STATE_WANT_SYNC));
577                 cb->cb_next = NULL;
578                 *(iclog->ic_callback_tail) = cb;
579                 iclog->ic_callback_tail = &(cb->cb_next);
580         }
581         spin_unlock(&iclog->ic_callback_lock);
582         return abortflg;
583 }
584 
585 int
586 xfs_log_release_iclog(
587         struct xfs_mount        *mp,
588         struct xlog_in_core     *iclog)
589 {
590         if (xlog_state_release_iclog(mp->m_log, iclog)) {
591                 xfs_force_shutdown(mp, SHUTDOWN_LOG_IO_ERROR);
592                 return EIO;
593         }
594 
595         return 0;
596 }
597 
598 /*
599  * Mount a log filesystem
600  *
601  * mp           - ubiquitous xfs mount point structure
602  * log_target   - buftarg of on-disk log device
603  * blk_offset   - Start block # where block size is 512 bytes (BBSIZE)
604  * num_bblocks  - Number of BBSIZE blocks in on-disk log
605  *
606  * Return error or zero.
607  */
608 int
609 xfs_log_mount(
610         xfs_mount_t     *mp,
611         xfs_buftarg_t   *log_target,
612         xfs_daddr_t     blk_offset,
613         int             num_bblks)
614 {
615         int             error;
616 
617         if (!(mp->m_flags & XFS_MOUNT_NORECOVERY))
618                 xfs_notice(mp, "Mounting Filesystem");
619         else {
620                 xfs_notice(mp,
621 "Mounting filesystem in no-recovery mode.  Filesystem will be inconsistent.");
622                 ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
623         }
624 
625         mp->m_log = xlog_alloc_log(mp, log_target, blk_offset, num_bblks);
626         if (IS_ERR(mp->m_log)) {
627                 error = -PTR_ERR(mp->m_log);
628                 goto out;
629         }
630 
631         /*
632          * Initialize the AIL now we have a log.
633          */
634         error = xfs_trans_ail_init(mp);
635         if (error) {
636                 xfs_warn(mp, "AIL initialisation failed: error %d", error);
637                 goto out_free_log;
638         }
639         mp->m_log->l_ailp = mp->m_ail;
640 
641         /*
642          * skip log recovery on a norecovery mount.  pretend it all
643          * just worked.
644          */
645         if (!(mp->m_flags & XFS_MOUNT_NORECOVERY)) {
646                 int     readonly = (mp->m_flags & XFS_MOUNT_RDONLY);
647 
648                 if (readonly)
649                         mp->m_flags &= ~XFS_MOUNT_RDONLY;
650 
651                 error = xlog_recover(mp->m_log);
652 
653                 if (readonly)
654                         mp->m_flags |= XFS_MOUNT_RDONLY;
655                 if (error) {
656                         xfs_warn(mp, "log mount/recovery failed: error %d",
657                                 error);
658                         goto out_destroy_ail;
659                 }
660         }
661 
662         /* Normal transactions can now occur */
663         mp->m_log->l_flags &= ~XLOG_ACTIVE_RECOVERY;
664 
665         /*
666          * Now the log has been fully initialised and we know were our
667          * space grant counters are, we can initialise the permanent ticket
668          * needed for delayed logging to work.
669          */
670         xlog_cil_init_post_recovery(mp->m_log);
671 
672         return 0;
673 
674 out_destroy_ail:
675         xfs_trans_ail_destroy(mp);
676 out_free_log:
677         xlog_dealloc_log(mp->m_log);
678 out:
679         return error;
680 }
681 
682 /*
683  * Finish the recovery of the file system.  This is separate from
684  * the xfs_log_mount() call, because it depends on the code in
685  * xfs_mountfs() to read in the root and real-time bitmap inodes
686  * between calling xfs_log_mount() and here.
687  *
688  * mp           - ubiquitous xfs mount point structure
689  */
690 int
691 xfs_log_mount_finish(xfs_mount_t *mp)
692 {
693         int     error;
694 
695         if (!(mp->m_flags & XFS_MOUNT_NORECOVERY))
696                 error = xlog_recover_finish(mp->m_log);
697         else {
698                 error = 0;
699                 ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
700         }
701 
702         return error;
703 }
704 
705 /*
706  * Final log writes as part of unmount.
707  *
708  * Mark the filesystem clean as unmount happens.  Note that during relocation
709  * this routine needs to be executed as part of source-bag while the
710  * deallocation must not be done until source-end.
711  */
712 
713 /*
714  * Unmount record used to have a string "Unmount filesystem--" in the
715  * data section where the "Un" was really a magic number (XLOG_UNMOUNT_TYPE).
716  * We just write the magic number now since that particular field isn't
717  * currently architecture converted and "nUmount" is a bit foo.
718  * As far as I know, there weren't any dependencies on the old behaviour.
719  */
720 
721 int
722 xfs_log_unmount_write(xfs_mount_t *mp)
723 {
724         struct xlog      *log = mp->m_log;
725         xlog_in_core_t   *iclog;
726 #ifdef DEBUG
727         xlog_in_core_t   *first_iclog;
728 #endif
729         xlog_ticket_t   *tic = NULL;
730         xfs_lsn_t        lsn;
731         int              error;
732 
733         /*
734          * Don't write out unmount record on read-only mounts.
735          * Or, if we are doing a forced umount (typically because of IO errors).
736          */
737         if (mp->m_flags & XFS_MOUNT_RDONLY)
738                 return 0;
739 
740         error = _xfs_log_force(mp, XFS_LOG_SYNC, NULL);
741         ASSERT(error || !(XLOG_FORCED_SHUTDOWN(log)));
742 
743 #ifdef DEBUG
744         first_iclog = iclog = log->l_iclog;
745         do {
746                 if (!(iclog->ic_state & XLOG_STATE_IOERROR)) {
747                         ASSERT(iclog->ic_state & XLOG_STATE_ACTIVE);
748                         ASSERT(iclog->ic_offset == 0);
749                 }
750                 iclog = iclog->ic_next;
751         } while (iclog != first_iclog);
752 #endif
753         if (! (XLOG_FORCED_SHUTDOWN(log))) {
754                 error = xfs_log_reserve(mp, 600, 1, &tic,
755                                         XFS_LOG, 0, XLOG_UNMOUNT_REC_TYPE);
756                 if (!error) {
757                         /* the data section must be 32 bit size aligned */
758                         struct {
759                             __uint16_t magic;
760                             __uint16_t pad1;
761                             __uint32_t pad2; /* may as well make it 64 bits */
762                         } magic = {
763                                 .magic = XLOG_UNMOUNT_TYPE,
764                         };
765                         struct xfs_log_iovec reg = {
766                                 .i_addr = &magic,
767                                 .i_len = sizeof(magic),
768                                 .i_type = XLOG_REG_TYPE_UNMOUNT,
769                         };
770                         struct xfs_log_vec vec = {
771                                 .lv_niovecs = 1,
772                                 .lv_iovecp = &reg,
773                         };
774 
775                         /* remove inited flag, and account for space used */
776                         tic->t_flags = 0;
777                         tic->t_curr_res -= sizeof(magic);
778                         error = xlog_write(log, &vec, tic, &lsn,
779                                            NULL, XLOG_UNMOUNT_TRANS);
780                         /*
781                          * At this point, we're umounting anyway,
782                          * so there's no point in transitioning log state
783                          * to IOERROR. Just continue...
784                          */
785                 }
786 
787                 if (error)
788                         xfs_alert(mp, "%s: unmount record failed", __func__);
789 
790 
791                 spin_lock(&log->l_icloglock);
792                 iclog = log->l_iclog;
793                 atomic_inc(&iclog->ic_refcnt);
794                 xlog_state_want_sync(log, iclog);
795                 spin_unlock(&log->l_icloglock);
796                 error = xlog_state_release_iclog(log, iclog);
797 
798                 spin_lock(&log->l_icloglock);
799                 if (!(iclog->ic_state == XLOG_STATE_ACTIVE ||
800                       iclog->ic_state == XLOG_STATE_DIRTY)) {
801                         if (!XLOG_FORCED_SHUTDOWN(log)) {
802                                 xlog_wait(&iclog->ic_force_wait,
803                                                         &log->l_icloglock);
804                         } else {
805                                 spin_unlock(&log->l_icloglock);
806                         }
807                 } else {
808                         spin_unlock(&log->l_icloglock);
809                 }
810                 if (tic) {
811                         trace_xfs_log_umount_write(log, tic);
812                         xlog_ungrant_log_space(log, tic);
813                         xfs_log_ticket_put(tic);
814                 }
815         } else {
816                 /*
817                  * We're already in forced_shutdown mode, couldn't
818                  * even attempt to write out the unmount transaction.
819                  *
820                  * Go through the motions of sync'ing and releasing
821                  * the iclog, even though no I/O will actually happen,
822                  * we need to wait for other log I/Os that may already
823                  * be in progress.  Do this as a separate section of
824                  * code so we'll know if we ever get stuck here that
825                  * we're in this odd situation of trying to unmount
826                  * a file system that went into forced_shutdown as
827                  * the result of an unmount..
828                  */
829                 spin_lock(&log->l_icloglock);
830                 iclog = log->l_iclog;
831                 atomic_inc(&iclog->ic_refcnt);
832 
833                 xlog_state_want_sync(log, iclog);
834                 spin_unlock(&log->l_icloglock);
835                 error =  xlog_state_release_iclog(log, iclog);
836 
837                 spin_lock(&log->l_icloglock);
838 
839                 if ( ! (   iclog->ic_state == XLOG_STATE_ACTIVE
840                         || iclog->ic_state == XLOG_STATE_DIRTY
841                         || iclog->ic_state == XLOG_STATE_IOERROR) ) {
842 
843                                 xlog_wait(&iclog->ic_force_wait,
844                                                         &log->l_icloglock);
845                 } else {
846                         spin_unlock(&log->l_icloglock);
847                 }
848         }
849 
850         return error;
851 }       /* xfs_log_unmount_write */
852 
853 /*
854  * Deallocate log structures for unmount/relocation.
855  *
856  * We need to stop the aild from running before we destroy
857  * and deallocate the log as the aild references the log.
858  */
859 void
860 xfs_log_unmount(xfs_mount_t *mp)
861 {
862         cancel_delayed_work_sync(&mp->m_sync_work);
863         xfs_trans_ail_destroy(mp);
864         xlog_dealloc_log(mp->m_log);
865 }
866 
867 void
868 xfs_log_item_init(
869         struct xfs_mount        *mp,
870         struct xfs_log_item     *item,
871         int                     type,
872         const struct xfs_item_ops *ops)
873 {
874         item->li_mountp = mp;
875         item->li_ailp = mp->m_ail;
876         item->li_type = type;
877         item->li_ops = ops;
878         item->li_lv = NULL;
879 
880         INIT_LIST_HEAD(&item->li_ail);
881         INIT_LIST_HEAD(&item->li_cil);
882 }
883 
884 /*
885  * Wake up processes waiting for log space after we have moved the log tail.
886  */
887 void
888 xfs_log_space_wake(
889         struct xfs_mount        *mp)
890 {
891         struct xlog             *log = mp->m_log;
892         int                     free_bytes;
893 
894         if (XLOG_FORCED_SHUTDOWN(log))
895                 return;
896 
897         if (!list_empty_careful(&log->l_write_head.waiters)) {
898                 ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
899 
900                 spin_lock(&log->l_write_head.lock);
901                 free_bytes = xlog_space_left(log, &log->l_write_head.grant);
902                 xlog_grant_head_wake(log, &log->l_write_head, &free_bytes);
903                 spin_unlock(&log->l_write_head.lock);
904         }
905 
906         if (!list_empty_careful(&log->l_reserve_head.waiters)) {
907                 ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
908 
909                 spin_lock(&log->l_reserve_head.lock);
910                 free_bytes = xlog_space_left(log, &log->l_reserve_head.grant);
911                 xlog_grant_head_wake(log, &log->l_reserve_head, &free_bytes);
912                 spin_unlock(&log->l_reserve_head.lock);
913         }
914 }
915 
916 /*
917  * Determine if we have a transaction that has gone to disk
918  * that needs to be covered. To begin the transition to the idle state
919  * firstly the log needs to be idle (no AIL and nothing in the iclogs).
920  * If we are then in a state where covering is needed, the caller is informed
921  * that dummy transactions are required to move the log into the idle state.
922  *
923  * Because this is called as part of the sync process, we should also indicate
924  * that dummy transactions should be issued in anything but the covered or
925  * idle states. This ensures that the log tail is accurately reflected in
926  * the log at the end of the sync, hence if a crash occurrs avoids replay
927  * of transactions where the metadata is already on disk.
928  */
929 int
930 xfs_log_need_covered(xfs_mount_t *mp)
931 {
932         int             needed = 0;
933         struct xlog     *log = mp->m_log;
934 
935         if (!xfs_fs_writable(mp))
936                 return 0;
937 
938         spin_lock(&log->l_icloglock);
939         switch (log->l_covered_state) {
940         case XLOG_STATE_COVER_DONE:
941         case XLOG_STATE_COVER_DONE2:
942         case XLOG_STATE_COVER_IDLE:
943                 break;
944         case XLOG_STATE_COVER_NEED:
945         case XLOG_STATE_COVER_NEED2:
946                 if (!xfs_ail_min_lsn(log->l_ailp) &&
947                     xlog_iclogs_empty(log)) {
948                         if (log->l_covered_state == XLOG_STATE_COVER_NEED)
949                                 log->l_covered_state = XLOG_STATE_COVER_DONE;
950                         else
951                                 log->l_covered_state = XLOG_STATE_COVER_DONE2;
952                 }
953                 /* FALLTHRU */
954         default:
955                 needed = 1;
956                 break;
957         }
958         spin_unlock(&log->l_icloglock);
959         return needed;
960 }
961 
962 /*
963  * We may be holding the log iclog lock upon entering this routine.
964  */
965 xfs_lsn_t
966 xlog_assign_tail_lsn_locked(
967         struct xfs_mount        *mp)
968 {
969         struct xlog             *log = mp->m_log;
970         struct xfs_log_item     *lip;
971         xfs_lsn_t               tail_lsn;
972 
973         assert_spin_locked(&mp->m_ail->xa_lock);
974 
975         /*
976          * To make sure we always have a valid LSN for the log tail we keep
977          * track of the last LSN which was committed in log->l_last_sync_lsn,
978          * and use that when the AIL was empty.
979          */
980         lip = xfs_ail_min(mp->m_ail);
981         if (lip)
982                 tail_lsn = lip->li_lsn;
983         else
984                 tail_lsn = atomic64_read(&log->l_last_sync_lsn);
985         atomic64_set(&log->l_tail_lsn, tail_lsn);
986         return tail_lsn;
987 }
988 
989 xfs_lsn_t
990 xlog_assign_tail_lsn(
991         struct xfs_mount        *mp)
992 {
993         xfs_lsn_t               tail_lsn;
994 
995         spin_lock(&mp->m_ail->xa_lock);
996         tail_lsn = xlog_assign_tail_lsn_locked(mp);
997         spin_unlock(&mp->m_ail->xa_lock);
998 
999         return tail_lsn;
1000 }
1001 
1002 /*
1003  * Return the space in the log between the tail and the head.  The head
1004  * is passed in the cycle/bytes formal parms.  In the special case where
1005  * the reserve head has wrapped passed the tail, this calculation is no
1006  * longer valid.  In this case, just return 0 which means there is no space
1007  * in the log.  This works for all places where this function is called
1008  * with the reserve head.  Of course, if the write head were to ever
1009  * wrap the tail, we should blow up.  Rather than catch this case here,
1010  * we depend on other ASSERTions in other parts of the code.   XXXmiken
1011  *
1012  * This code also handles the case where the reservation head is behind
1013  * the tail.  The details of this case are described below, but the end
1014  * result is that we return the size of the log as the amount of space left.
1015  */
1016 STATIC int
1017 xlog_space_left(
1018         struct xlog     *log,
1019         atomic64_t      *head)
1020 {
1021         int             free_bytes;
1022         int             tail_bytes;
1023         int             tail_cycle;
1024         int             head_cycle;
1025         int             head_bytes;
1026 
1027         xlog_crack_grant_head(head, &head_cycle, &head_bytes);
1028         xlog_crack_atomic_lsn(&log->l_tail_lsn, &tail_cycle, &tail_bytes);
1029         tail_bytes = BBTOB(tail_bytes);
1030         if (tail_cycle == head_cycle && head_bytes >= tail_bytes)
1031                 free_bytes = log->l_logsize - (head_bytes - tail_bytes);
1032         else if (tail_cycle + 1 < head_cycle)
1033                 return 0;
1034         else if (tail_cycle < head_cycle) {
1035                 ASSERT(tail_cycle == (head_cycle - 1));
1036                 free_bytes = tail_bytes - head_bytes;
1037         } else {
1038                 /*
1039                  * The reservation head is behind the tail.
1040                  * In this case we just want to return the size of the
1041                  * log as the amount of space left.
1042                  */
1043                 xfs_alert(log->l_mp,
1044                         "xlog_space_left: head behind tail\n"
1045                         "  tail_cycle = %d, tail_bytes = %d\n"
1046                         "  GH   cycle = %d, GH   bytes = %d",
1047                         tail_cycle, tail_bytes, head_cycle, head_bytes);
1048                 ASSERT(0);
1049                 free_bytes = log->l_logsize;
1050         }
1051         return free_bytes;
1052 }
1053 
1054 
1055 /*
1056  * Log function which is called when an io completes.
1057  *
1058  * The log manager needs its own routine, in order to control what
1059  * happens with the buffer after the write completes.
1060  */
1061 void
1062 xlog_iodone(xfs_buf_t *bp)
1063 {
1064         struct xlog_in_core     *iclog = bp->b_fspriv;
1065         struct xlog             *l = iclog->ic_log;
1066         int                     aborted = 0;
1067 
1068         /*
1069          * Race to shutdown the filesystem if we see an error.
1070          */
1071         if (XFS_TEST_ERROR((xfs_buf_geterror(bp)), l->l_mp,
1072                         XFS_ERRTAG_IODONE_IOERR, XFS_RANDOM_IODONE_IOERR)) {
1073                 xfs_buf_ioerror_alert(bp, __func__);
1074                 xfs_buf_stale(bp);
1075                 xfs_force_shutdown(l->l_mp, SHUTDOWN_LOG_IO_ERROR);
1076                 /*
1077                  * This flag will be propagated to the trans-committed
1078                  * callback routines to let them know that the log-commit
1079                  * didn't succeed.
1080                  */
1081                 aborted = XFS_LI_ABORTED;
1082         } else if (iclog->ic_state & XLOG_STATE_IOERROR) {
1083                 aborted = XFS_LI_ABORTED;
1084         }
1085 
1086         /* log I/O is always issued ASYNC */
1087         ASSERT(XFS_BUF_ISASYNC(bp));
1088         xlog_state_done_syncing(iclog, aborted);
1089         /*
1090          * do not reference the buffer (bp) here as we could race
1091          * with it being freed after writing the unmount record to the
1092          * log.
1093          */
1094 
1095 }       /* xlog_iodone */
1096 
1097 /*
1098  * Return size of each in-core log record buffer.
1099  *
1100  * All machines get 8 x 32kB buffers by default, unless tuned otherwise.
1101  *
1102  * If the filesystem blocksize is too large, we may need to choose a
1103  * larger size since the directory code currently logs entire blocks.
1104  */
1105 
1106 STATIC void
1107 xlog_get_iclog_buffer_size(
1108         struct xfs_mount        *mp,
1109         struct xlog             *log)
1110 {
1111         int size;
1112         int xhdrs;
1113 
1114         if (mp->m_logbufs <= 0)
1115                 log->l_iclog_bufs = XLOG_MAX_ICLOGS;
1116         else
1117                 log->l_iclog_bufs = mp->m_logbufs;
1118 
1119         /*
1120          * Buffer size passed in from mount system call.
1121          */
1122         if (mp->m_logbsize > 0) {
1123                 size = log->l_iclog_size = mp->m_logbsize;
1124                 log->l_iclog_size_log = 0;
1125                 while (size != 1) {
1126                         log->l_iclog_size_log++;
1127                         size >>= 1;
1128                 }
1129 
1130                 if (xfs_sb_version_haslogv2(&mp->m_sb)) {
1131                         /* # headers = size / 32k
1132                          * one header holds cycles from 32k of data
1133                          */
1134 
1135                         xhdrs = mp->m_logbsize / XLOG_HEADER_CYCLE_SIZE;
1136                         if (mp->m_logbsize % XLOG_HEADER_CYCLE_SIZE)
1137                                 xhdrs++;
1138                         log->l_iclog_hsize = xhdrs << BBSHIFT;
1139                         log->l_iclog_heads = xhdrs;
1140                 } else {
1141                         ASSERT(mp->m_logbsize <= XLOG_BIG_RECORD_BSIZE);
1142                         log->l_iclog_hsize = BBSIZE;
1143                         log->l_iclog_heads = 1;
1144                 }
1145                 goto done;
1146         }
1147 
1148         /* All machines use 32kB buffers by default. */
1149         log->l_iclog_size = XLOG_BIG_RECORD_BSIZE;
1150         log->l_iclog_size_log = XLOG_BIG_RECORD_BSHIFT;
1151 
1152         /* the default log size is 16k or 32k which is one header sector */
1153         log->l_iclog_hsize = BBSIZE;
1154         log->l_iclog_heads = 1;
1155 
1156 done:
1157         /* are we being asked to make the sizes selected above visible? */
1158         if (mp->m_logbufs == 0)
1159                 mp->m_logbufs = log->l_iclog_bufs;
1160         if (mp->m_logbsize == 0)
1161                 mp->m_logbsize = log->l_iclog_size;
1162 }       /* xlog_get_iclog_buffer_size */
1163 
1164 
1165 /*
1166  * This routine initializes some of the log structure for a given mount point.
1167  * Its primary purpose is to fill in enough, so recovery can occur.  However,
1168  * some other stuff may be filled in too.
1169  */
1170 STATIC struct xlog *
1171 xlog_alloc_log(
1172         struct xfs_mount        *mp,
1173         struct xfs_buftarg      *log_target,
1174         xfs_daddr_t             blk_offset,
1175         int                     num_bblks)
1176 {
1177         struct xlog             *log;
1178         xlog_rec_header_t       *head;
1179         xlog_in_core_t          **iclogp;
1180         xlog_in_core_t          *iclog, *prev_iclog=NULL;
1181         xfs_buf_t               *bp;
1182         int                     i;
1183         int                     error = ENOMEM;
1184         uint                    log2_size = 0;
1185 
1186         log = kmem_zalloc(sizeof(struct xlog), KM_MAYFAIL);
1187         if (!log) {
1188                 xfs_warn(mp, "Log allocation failed: No memory!");
1189                 goto out;
1190         }
1191 
1192         log->l_mp          = mp;
1193         log->l_targ        = log_target;
1194         log->l_logsize     = BBTOB(num_bblks);
1195         log->l_logBBstart  = blk_offset;
1196         log->l_logBBsize   = num_bblks;
1197         log->l_covered_state = XLOG_STATE_COVER_IDLE;
1198         log->l_flags       |= XLOG_ACTIVE_RECOVERY;
1199 
1200         log->l_prev_block  = -1;
1201         /* log->l_tail_lsn = 0x100000000LL; cycle = 1; current block = 0 */
1202         xlog_assign_atomic_lsn(&log->l_tail_lsn, 1, 0);
1203         xlog_assign_atomic_lsn(&log->l_last_sync_lsn, 1, 0);
1204         log->l_curr_cycle  = 1;     /* 0 is bad since this is initial value */
1205 
1206         xlog_grant_head_init(&log->l_reserve_head);
1207         xlog_grant_head_init(&log->l_write_head);
1208 
1209         error = EFSCORRUPTED;
1210         if (xfs_sb_version_hassector(&mp->m_sb)) {
1211                 log2_size = mp->m_sb.sb_logsectlog;
1212                 if (log2_size < BBSHIFT) {
1213                         xfs_warn(mp, "Log sector size too small (0x%x < 0x%x)",
1214                                 log2_size, BBSHIFT);
1215                         goto out_free_log;
1216                 }
1217 
1218                 log2_size -= BBSHIFT;
1219                 if (log2_size > mp->m_sectbb_log) {
1220                         xfs_warn(mp, "Log sector size too large (0x%x > 0x%x)",
1221                                 log2_size, mp->m_sectbb_log);
1222                         goto out_free_log;
1223                 }
1224 
1225                 /* for larger sector sizes, must have v2 or external log */
1226                 if (log2_size && log->l_logBBstart > 0 &&
1227                             !xfs_sb_version_haslogv2(&mp->m_sb)) {
1228                         xfs_warn(mp,
1229                 "log sector size (0x%x) invalid for configuration.",
1230                                 log2_size);
1231                         goto out_free_log;
1232                 }
1233         }
1234         log->l_sectBBsize = 1 << log2_size;
1235 
1236         xlog_get_iclog_buffer_size(mp, log);
1237 
1238         error = ENOMEM;
1239         bp = xfs_buf_alloc(mp->m_logdev_targp, 0, BTOBB(log->l_iclog_size), 0);
1240         if (!bp)
1241                 goto out_free_log;
1242         bp->b_iodone = xlog_iodone;
1243         ASSERT(xfs_buf_islocked(bp));
1244         log->l_xbuf = bp;
1245 
1246         spin_lock_init(&log->l_icloglock);
1247         init_waitqueue_head(&log->l_flush_wait);
1248 
1249         iclogp = &log->l_iclog;
1250         /*
1251          * The amount of memory to allocate for the iclog structure is
1252          * rather funky due to the way the structure is defined.  It is
1253          * done this way so that we can use different sizes for machines
1254          * with different amounts of memory.  See the definition of
1255          * xlog_in_core_t in xfs_log_priv.h for details.
1256          */
1257         ASSERT(log->l_iclog_size >= 4096);
1258         for (i=0; i < log->l_iclog_bufs; i++) {
1259                 *iclogp = kmem_zalloc(sizeof(xlog_in_core_t), KM_MAYFAIL);
1260                 if (!*iclogp)
1261                         goto out_free_iclog;
1262 
1263                 iclog = *iclogp;
1264                 iclog->ic_prev = prev_iclog;
1265                 prev_iclog = iclog;
1266 
1267                 bp = xfs_buf_get_uncached(mp->m_logdev_targp,
1268                                                 BTOBB(log->l_iclog_size), 0);
1269                 if (!bp)
1270                         goto out_free_iclog;
1271 
1272                 bp->b_iodone = xlog_iodone;
1273                 iclog->ic_bp = bp;
1274                 iclog->ic_data = bp->b_addr;
1275 #ifdef DEBUG
1276                 log->l_iclog_bak[i] = (xfs_caddr_t)&(iclog->ic_header);
1277 #endif
1278                 head = &iclog->ic_header;
1279                 memset(head, 0, sizeof(xlog_rec_header_t));
1280                 head->h_magicno = cpu_to_be32(XLOG_HEADER_MAGIC_NUM);
1281                 head->h_version = cpu_to_be32(
1282                         xfs_sb_version_haslogv2(&log->l_mp->m_sb) ? 2 : 1);
1283                 head->h_size = cpu_to_be32(log->l_iclog_size);
1284                 /* new fields */
1285                 head->h_fmt = cpu_to_be32(XLOG_FMT);
1286                 memcpy(&head->h_fs_uuid, &mp->m_sb.sb_uuid, sizeof(uuid_t));
1287 
1288                 iclog->ic_size = BBTOB(bp->b_length) - log->l_iclog_hsize;
1289                 iclog->ic_state = XLOG_STATE_ACTIVE;
1290                 iclog->ic_log = log;
1291                 atomic_set(&iclog->ic_refcnt, 0);
1292                 spin_lock_init(&iclog->ic_callback_lock);
1293                 iclog->ic_callback_tail = &(iclog->ic_callback);
1294                 iclog->ic_datap = (char *)iclog->ic_data + log->l_iclog_hsize;
1295 
1296                 ASSERT(xfs_buf_islocked(iclog->ic_bp));
1297                 init_waitqueue_head(&iclog->ic_force_wait);
1298                 init_waitqueue_head(&iclog->ic_write_wait);
1299 
1300                 iclogp = &iclog->ic_next;
1301         }
1302         *iclogp = log->l_iclog;                 /* complete ring */
1303         log->l_iclog->ic_prev = prev_iclog;     /* re-write 1st prev ptr */
1304 
1305         error = xlog_cil_init(log);
1306         if (error)
1307                 goto out_free_iclog;
1308         return log;
1309 
1310 out_free_iclog:
1311         for (iclog = log->l_iclog; iclog; iclog = prev_iclog) {
1312                 prev_iclog = iclog->ic_next;
1313                 if (iclog->ic_bp)
1314                         xfs_buf_free(iclog->ic_bp);
1315                 kmem_free(iclog);
1316         }
1317         spinlock_destroy(&log->l_icloglock);
1318         xfs_buf_free(log->l_xbuf);
1319 out_free_log:
1320         kmem_free(log);
1321 out:
1322         return ERR_PTR(-error);
1323 }       /* xlog_alloc_log */
1324 
1325 
1326 /*
1327  * Write out the commit record of a transaction associated with the given
1328  * ticket.  Return the lsn of the commit record.
1329  */
1330 STATIC int
1331 xlog_commit_record(
1332         struct xlog             *log,
1333         struct xlog_ticket      *ticket,
1334         struct xlog_in_core     **iclog,
1335         xfs_lsn_t               *commitlsnp)
1336 {
1337         struct xfs_mount *mp = log->l_mp;
1338         int     error;
1339         struct xfs_log_iovec reg = {
1340                 .i_addr = NULL,
1341                 .i_len = 0,
1342                 .i_type = XLOG_REG_TYPE_COMMIT,
1343         };
1344         struct xfs_log_vec vec = {
1345                 .lv_niovecs = 1,
1346                 .lv_iovecp = &reg,
1347         };
1348 
1349         ASSERT_ALWAYS(iclog);
1350         error = xlog_write(log, &vec, ticket, commitlsnp, iclog,
1351                                         XLOG_COMMIT_TRANS);
1352         if (error)
1353                 xfs_force_shutdown(mp, SHUTDOWN_LOG_IO_ERROR);
1354         return error;
1355 }
1356 
1357 /*
1358  * Push on the buffer cache code if we ever use more than 75% of the on-disk
1359  * log space.  This code pushes on the lsn which would supposedly free up
1360  * the 25% which we want to leave free.  We may need to adopt a policy which
1361  * pushes on an lsn which is further along in the log once we reach the high
1362  * water mark.  In this manner, we would be creating a low water mark.
1363  */
1364 STATIC void
1365 xlog_grant_push_ail(
1366         struct xlog     *log,
1367         int             need_bytes)
1368 {
1369         xfs_lsn_t       threshold_lsn = 0;
1370         xfs_lsn_t       last_sync_lsn;
1371         int             free_blocks;
1372         int             free_bytes;
1373         int             threshold_block;
1374         int             threshold_cycle;
1375         int             free_threshold;
1376 
1377         ASSERT(BTOBB(need_bytes) < log->l_logBBsize);
1378 
1379         free_bytes = xlog_space_left(log, &log->l_reserve_head.grant);
1380         free_blocks = BTOBBT(free_bytes);
1381 
1382         /*
1383          * Set the threshold for the minimum number of free blocks in the
1384          * log to the maximum of what the caller needs, one quarter of the
1385          * log, and 256 blocks.
1386          */
1387         free_threshold = BTOBB(need_bytes);
1388         free_threshold = MAX(free_threshold, (log->l_logBBsize >> 2));
1389         free_threshold = MAX(free_threshold, 256);
1390         if (free_blocks >= free_threshold)
1391                 return;
1392 
1393         xlog_crack_atomic_lsn(&log->l_tail_lsn, &threshold_cycle,
1394                                                 &threshold_block);
1395         threshold_block += free_threshold;
1396         if (threshold_block >= log->l_logBBsize) {
1397                 threshold_block -= log->l_logBBsize;
1398                 threshold_cycle += 1;
1399         }
1400         threshold_lsn = xlog_assign_lsn(threshold_cycle,
1401                                         threshold_block);
1402         /*
1403          * Don't pass in an lsn greater than the lsn of the last
1404          * log record known to be on disk. Use a snapshot of the last sync lsn
1405          * so that it doesn't change between the compare and the set.
1406          */
1407         last_sync_lsn = atomic64_read(&log->l_last_sync_lsn);
1408         if (XFS_LSN_CMP(threshold_lsn, last_sync_lsn) > 0)
1409                 threshold_lsn = last_sync_lsn;
1410 
1411         /*
1412          * Get the transaction layer to kick the dirty buffers out to
1413          * disk asynchronously. No point in trying to do this if
1414          * the filesystem is shutting down.
1415          */
1416         if (!XLOG_FORCED_SHUTDOWN(log))
1417                 xfs_ail_push(log->l_ailp, threshold_lsn);
1418 }
1419 
1420 /*
1421  * The bdstrat callback function for log bufs. This gives us a central
1422  * place to trap bufs in case we get hit by a log I/O error and need to
1423  * shutdown. Actually, in practice, even when we didn't get a log error,
1424  * we transition the iclogs to IOERROR state *after* flushing all existing
1425  * iclogs to disk. This is because we don't want anymore new transactions to be
1426  * started or completed afterwards.
1427  */
1428 STATIC int
1429 xlog_bdstrat(
1430         struct xfs_buf          *bp)
1431 {
1432         struct xlog_in_core     *iclog = bp->b_fspriv;
1433 
1434         if (iclog->ic_state & XLOG_STATE_IOERROR) {
1435                 xfs_buf_ioerror(bp, EIO);
1436                 xfs_buf_stale(bp);
1437                 xfs_buf_ioend(bp, 0);
1438                 /*
1439                  * It would seem logical to return EIO here, but we rely on
1440                  * the log state machine to propagate I/O errors instead of
1441                  * doing it here.
1442                  */
1443                 return 0;
1444         }
1445 
1446         xfs_buf_iorequest(bp);
1447         return 0;
1448 }
1449 
1450 /*
1451  * Flush out the in-core log (iclog) to the on-disk log in an asynchronous 
1452  * fashion.  Previously, we should have moved the current iclog
1453  * ptr in the log to point to the next available iclog.  This allows further
1454  * write to continue while this code syncs out an iclog ready to go.
1455  * Before an in-core log can be written out, the data section must be scanned
1456  * to save away the 1st word of each BBSIZE block into the header.  We replace
1457  * it with the current cycle count.  Each BBSIZE block is tagged with the
1458  * cycle count because there in an implicit assumption that drives will
1459  * guarantee that entire 512 byte blocks get written at once.  In other words,
1460  * we can't have part of a 512 byte block written and part not written.  By
1461  * tagging each block, we will know which blocks are valid when recovering
1462  * after an unclean shutdown.
1463  *
1464  * This routine is single threaded on the iclog.  No other thread can be in
1465  * this routine with the same iclog.  Changing contents of iclog can there-
1466  * fore be done without grabbing the state machine lock.  Updating the global
1467  * log will require grabbing the lock though.
1468  *
1469  * The entire log manager uses a logical block numbering scheme.  Only
1470  * log_sync (and then only bwrite()) know about the fact that the log may
1471  * not start with block zero on a given device.  The log block start offset
1472  * is added immediately before calling bwrite().
1473  */
1474 
1475 STATIC int
1476 xlog_sync(
1477         struct xlog             *log,
1478         struct xlog_in_core     *iclog)
1479 {
1480         xfs_caddr_t     dptr;           /* pointer to byte sized element */
1481         xfs_buf_t       *bp;
1482         int             i;
1483         uint            count;          /* byte count of bwrite */
1484         uint            count_init;     /* initial count before roundup */
1485         int             roundoff;       /* roundoff to BB or stripe */
1486         int             split = 0;      /* split write into two regions */
1487         int             error;
1488         int             v2 = xfs_sb_version_haslogv2(&log->l_mp->m_sb);
1489 
1490         XFS_STATS_INC(xs_log_writes);
1491         ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
1492 
1493         /* Add for LR header */
1494         count_init = log->l_iclog_hsize + iclog->ic_offset;
1495 
1496         /* Round out the log write size */
1497         if (v2 && log->l_mp->m_sb.sb_logsunit > 1) {
1498                 /* we have a v2 stripe unit to use */
1499                 count = XLOG_LSUNITTOB(log, XLOG_BTOLSUNIT(log, count_init));
1500         } else {
1501                 count = BBTOB(BTOBB(count_init));
1502         }
1503         roundoff = count - count_init;
1504         ASSERT(roundoff >= 0);
1505         ASSERT((v2 && log->l_mp->m_sb.sb_logsunit > 1 && 
1506                 roundoff < log->l_mp->m_sb.sb_logsunit)
1507                 || 
1508                 (log->l_mp->m_sb.sb_logsunit <= 1 && 
1509                  roundoff < BBTOB(1)));
1510 
1511         /* move grant heads by roundoff in sync */
1512         xlog_grant_add_space(log, &log->l_reserve_head.grant, roundoff);
1513         xlog_grant_add_space(log, &log->l_write_head.grant, roundoff);
1514 
1515         /* put cycle number in every block */
1516         xlog_pack_data(log, iclog, roundoff); 
1517 
1518         /* real byte length */
1519         if (v2) {
1520                 iclog->ic_header.h_len =
1521                         cpu_to_be32(iclog->ic_offset + roundoff);
1522         } else {
1523                 iclog->ic_header.h_len =
1524                         cpu_to_be32(iclog->ic_offset);
1525         }
1526 
1527         bp = iclog->ic_bp;
1528         XFS_BUF_SET_ADDR(bp, BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn)));
1529 
1530         XFS_STATS_ADD(xs_log_blocks, BTOBB(count));
1531 
1532         /* Do we need to split this write into 2 parts? */
1533         if (XFS_BUF_ADDR(bp) + BTOBB(count) > log->l_logBBsize) {
1534                 split = count - (BBTOB(log->l_logBBsize - XFS_BUF_ADDR(bp)));
1535                 count = BBTOB(log->l_logBBsize - XFS_BUF_ADDR(bp));
1536                 iclog->ic_bwritecnt = 2;        /* split into 2 writes */
1537         } else {
1538                 iclog->ic_bwritecnt = 1;
1539         }
1540         bp->b_io_length = BTOBB(count);
1541         bp->b_fspriv = iclog;
1542         XFS_BUF_ZEROFLAGS(bp);
1543         XFS_BUF_ASYNC(bp);
1544         bp->b_flags |= XBF_SYNCIO;
1545 
1546         if (log->l_mp->m_flags & XFS_MOUNT_BARRIER) {
1547                 bp->b_flags |= XBF_FUA;
1548 
1549                 /*
1550                  * Flush the data device before flushing the log to make
1551                  * sure all meta data written back from the AIL actually made
1552                  * it to disk before stamping the new log tail LSN into the
1553                  * log buffer.  For an external log we need to issue the
1554                  * flush explicitly, and unfortunately synchronously here;
1555                  * for an internal log we can simply use the block layer
1556                  * state machine for preflushes.
1557                  */
1558                 if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp)
1559                         xfs_blkdev_issue_flush(log->l_mp->m_ddev_targp);
1560                 else
1561                         bp->b_flags |= XBF_FLUSH;
1562         }
1563 
1564         ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
1565         ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);
1566 
1567         xlog_verify_iclog(log, iclog, count, B_TRUE);
1568 
1569         /* account for log which doesn't start at block #0 */
1570         XFS_BUF_SET_ADDR(bp, XFS_BUF_ADDR(bp) + log->l_logBBstart);
1571         /*
1572          * Don't call xfs_bwrite here. We do log-syncs even when the filesystem
1573          * is shutting down.
1574          */
1575         XFS_BUF_WRITE(bp);
1576 
1577         error = xlog_bdstrat(bp);
1578         if (error) {
1579                 xfs_buf_ioerror_alert(bp, "xlog_sync");
1580                 return error;
1581         }
1582         if (split) {
1583                 bp = iclog->ic_log->l_xbuf;
1584                 XFS_BUF_SET_ADDR(bp, 0);             /* logical 0 */
1585                 xfs_buf_associate_memory(bp,
1586                                 (char *)&iclog->ic_header + count, split);
1587                 bp->b_fspriv = iclog;
1588                 XFS_BUF_ZEROFLAGS(bp);
1589                 XFS_BUF_ASYNC(bp);
1590                 bp->b_flags |= XBF_SYNCIO;
1591                 if (log->l_mp->m_flags & XFS_MOUNT_BARRIER)
1592                         bp->b_flags |= XBF_FUA;
1593                 dptr = bp->b_addr;
1594                 /*
1595                  * Bump the cycle numbers at the start of each block
1596                  * since this part of the buffer is at the start of
1597                  * a new cycle.  Watch out for the header magic number
1598                  * case, though.
1599                  */
1600                 for (i = 0; i < split; i += BBSIZE) {
1601                         be32_add_cpu((__be32 *)dptr, 1);
1602                         if (be32_to_cpu(*(__be32 *)dptr) == XLOG_HEADER_MAGIC_NUM)
1603                                 be32_add_cpu((__be32 *)dptr, 1);
1604                         dptr += BBSIZE;
1605                 }
1606 
1607                 ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
1608                 ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);
1609 
1610                 /* account for internal log which doesn't start at block #0 */
1611                 XFS_BUF_SET_ADDR(bp, XFS_BUF_ADDR(bp) + log->l_logBBstart);
1612                 XFS_BUF_WRITE(bp);
1613                 error = xlog_bdstrat(bp);
1614                 if (error) {
1615                         xfs_buf_ioerror_alert(bp, "xlog_sync (split)");
1616                         return error;
1617                 }
1618         }
1619         return 0;
1620 }       /* xlog_sync */
1621 
1622 
1623 /*
1624  * Deallocate a log structure
1625  */
1626 STATIC void
1627 xlog_dealloc_log(
1628         struct xlog     *log)
1629 {
1630         xlog_in_core_t  *iclog, *next_iclog;
1631         int             i;
1632 
1633         xlog_cil_destroy(log);
1634 
1635         /*
1636          * always need to ensure that the extra buffer does not point to memory
1637          * owned by another log buffer before we free it.
1638          */
1639         xfs_buf_set_empty(log->l_xbuf, BTOBB(log->l_iclog_size));
1640         xfs_buf_free(log->l_xbuf);
1641 
1642         iclog = log->l_iclog;
1643         for (i=0; i<log->l_iclog_bufs; i++) {
1644                 xfs_buf_free(iclog->ic_bp);
1645                 next_iclog = iclog->ic_next;
1646                 kmem_free(iclog);
1647                 iclog = next_iclog;
1648         }
1649         spinlock_destroy(&log->l_icloglock);
1650 
1651         log->l_mp->m_log = NULL;
1652         kmem_free(log);
1653 }       /* xlog_dealloc_log */
1654 
1655 /*
1656  * Update counters atomically now that memcpy is done.
1657  */
1658 /* ARGSUSED */
1659 static inline void
1660 xlog_state_finish_copy(
1661         struct xlog             *log,
1662         struct xlog_in_core     *iclog,
1663         int                     record_cnt,
1664         int                     copy_bytes)
1665 {
1666         spin_lock(&log->l_icloglock);
1667 
1668         be32_add_cpu(&iclog->ic_header.h_num_logops, record_cnt);
1669         iclog->ic_offset += copy_bytes;
1670 
1671         spin_unlock(&log->l_icloglock);
1672 }       /* xlog_state_finish_copy */
1673 
1674 
1675 
1676 
1677 /*
1678  * print out info relating to regions written which consume
1679  * the reservation
1680  */
1681 void
1682 xlog_print_tic_res(
1683         struct xfs_mount        *mp,
1684         struct xlog_ticket      *ticket)
1685 {
1686         uint i;
1687         uint ophdr_spc = ticket->t_res_num_ophdrs * (uint)sizeof(xlog_op_header_t);
1688 
1689         /* match with XLOG_REG_TYPE_* in xfs_log.h */
1690         static char *res_type_str[XLOG_REG_TYPE_MAX] = {
1691             "bformat",
1692             "bchunk",
1693             "efi_format",
1694             "efd_format",
1695             "iformat",
1696             "icore",
1697             "iext",
1698             "ibroot",
1699             "ilocal",
1700             "iattr_ext",
1701             "iattr_broot",
1702             "iattr_local",
1703             "qformat",
1704             "dquot",
1705             "quotaoff",
1706             "LR header",
1707             "unmount",
1708             "commit",
1709             "trans header"
1710         };
1711         static char *trans_type_str[XFS_TRANS_TYPE_MAX] = {
1712             "SETATTR_NOT_SIZE",
1713             "SETATTR_SIZE",
1714             "INACTIVE",
1715             "CREATE",
1716             "CREATE_TRUNC",
1717             "TRUNCATE_FILE",
1718             "REMOVE",
1719             "LINK",
1720             "RENAME",
1721             "MKDIR",
1722             "RMDIR",
1723             "SYMLINK",
1724             "SET_DMATTRS",
1725             "GROWFS",
1726             "STRAT_WRITE",
1727             "DIOSTRAT",
1728             "WRITE_SYNC",
1729             "WRITEID",
1730             "ADDAFORK",
1731             "ATTRINVAL",
1732             "ATRUNCATE",
1733             "ATTR_SET",
1734             "ATTR_RM",
1735             "ATTR_FLAG",
1736             "CLEAR_AGI_BUCKET",
1737             "QM_SBCHANGE",
1738             "DUMMY1",
1739             "DUMMY2",
1740             "QM_QUOTAOFF",
1741             "QM_DQALLOC",
1742             "QM_SETQLIM",
1743             "QM_DQCLUSTER",
1744             "QM_QINOCREATE",
1745             "QM_QUOTAOFF_END",
1746             "SB_UNIT",
1747             "FSYNC_TS",
1748             "GROWFSRT_ALLOC",
1749             "GROWFSRT_ZERO",
1750             "GROWFSRT_FREE",
1751             "SWAPEXT"
1752         };
1753 
1754         xfs_warn(mp,
1755                 "xlog_write: reservation summary:\n"
1756                 "  trans type  = %s (%u)\n"
1757                 "  unit res    = %d bytes\n"
1758                 "  current res = %d bytes\n"
1759                 "  total reg   = %u bytes (o/flow = %u bytes)\n"
1760                 "  ophdrs      = %u (ophdr space = %u bytes)\n"
1761                 "  ophdr + reg = %u bytes\n"
1762                 "  num regions = %u\n",
1763                 ((ticket->t_trans_type <= 0 ||
1764                   ticket->t_trans_type > XFS_TRANS_TYPE_MAX) ?
1765                   "bad-trans-type" : trans_type_str[ticket->t_trans_type-1]),
1766                 ticket->t_trans_type,
1767                 ticket->t_unit_res,
1768                 ticket->t_curr_res,
1769                 ticket->t_res_arr_sum, ticket->t_res_o_flow,
1770                 ticket->t_res_num_ophdrs, ophdr_spc,
1771                 ticket->t_res_arr_sum +
1772                 ticket->t_res_o_flow + ophdr_spc,
1773                 ticket->t_res_num);
1774 
1775         for (i = 0; i < ticket->t_res_num; i++) {
1776                 uint r_type = ticket->t_res_arr[i].r_type;
1777                 xfs_warn(mp, "region[%u]: %s - %u bytes\n", i,
1778                             ((r_type <= 0 || r_type > XLOG_REG_TYPE_MAX) ?
1779                             "bad-rtype" : res_type_str[r_type-1]),
1780                             ticket->t_res_arr[i].r_len);
1781         }
1782 
1783         xfs_alert_tag(mp, XFS_PTAG_LOGRES,
1784                 "xlog_write: reservation ran out. Need to up reservation");
1785         xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
1786 }
1787 
1788 /*
1789  * Calculate the potential space needed by the log vector.  Each region gets
1790  * its own xlog_op_header_t and may need to be double word aligned.
1791  */
1792 static int
1793 xlog_write_calc_vec_length(
1794         struct xlog_ticket      *ticket,
1795         struct xfs_log_vec      *log_vector)
1796 {
1797         struct xfs_log_vec      *lv;
1798         int                     headers = 0;
1799         int                     len = 0;
1800         int                     i;
1801 
1802         /* acct for start rec of xact */
1803         if (ticket->t_flags & XLOG_TIC_INITED)
1804                 headers++;
1805 
1806         for (lv = log_vector; lv; lv = lv->lv_next) {
1807                 headers += lv->lv_niovecs;
1808 
1809                 for (i = 0; i < lv->lv_niovecs; i++) {
1810                         struct xfs_log_iovec    *vecp = &lv->lv_iovecp[i];
1811 
1812                         len += vecp->i_len;
1813                         xlog_tic_add_region(ticket, vecp->i_len, vecp->i_type);
1814                 }
1815         }
1816 
1817         ticket->t_res_num_ophdrs += headers;
1818         len += headers * sizeof(struct xlog_op_header);
1819 
1820         return len;
1821 }
1822 
1823 /*
1824  * If first write for transaction, insert start record  We can't be trying to
1825  * commit if we are inited.  We can't have any "partial_copy" if we are inited.
1826  */
1827 static int
1828 xlog_write_start_rec(
1829         struct xlog_op_header   *ophdr,
1830         struct xlog_ticket      *ticket)
1831 {
1832         if (!(ticket->t_flags & XLOG_TIC_INITED))
1833                 return 0;
1834 
1835         ophdr->oh_tid   = cpu_to_be32(ticket->t_tid);
1836         ophdr->oh_clientid = ticket->t_clientid;
1837         ophdr->oh_len = 0;
1838         ophdr->oh_flags = XLOG_START_TRANS;
1839         ophdr->oh_res2 = 0;
1840 
1841         ticket->t_flags &= ~XLOG_TIC_INITED;
1842 
1843         return sizeof(struct xlog_op_header);
1844 }
1845 
1846 static xlog_op_header_t *
1847 xlog_write_setup_ophdr(
1848         struct xlog             *log,
1849         struct xlog_op_header   *ophdr,
1850         struct xlog_ticket      *ticket,
1851         uint                    flags)
1852 {
1853         ophdr->oh_tid = cpu_to_be32(ticket->t_tid);
1854         ophdr->oh_clientid = ticket->t_clientid;
1855         ophdr->oh_res2 = 0;
1856 
1857         /* are we copying a commit or unmount record? */
1858         ophdr->oh_flags = flags;
1859 
1860         /*
1861          * We've seen logs corrupted with bad transaction client ids.  This
1862          * makes sure that XFS doesn't generate them on.  Turn this into an EIO
1863          * and shut down the filesystem.
1864          */
1865         switch (ophdr->oh_clientid)  {
1866         case XFS_TRANSACTION:
1867         case XFS_VOLUME:
1868         case XFS_LOG:
1869                 break;
1870         default:
1871                 xfs_warn(log->l_mp,
1872                         "Bad XFS transaction clientid 0x%x in ticket 0x%p",
1873                         ophdr->oh_clientid, ticket);
1874                 return NULL;
1875         }
1876 
1877         return ophdr;
1878 }
1879 
1880 /*
1881  * Set up the parameters of the region copy into the log. This has
1882  * to handle region write split across multiple log buffers - this
1883  * state is kept external to this function so that this code can
1884  * can be written in an obvious, self documenting manner.
1885  */
1886 static int
1887 xlog_write_setup_copy(
1888         struct xlog_ticket      *ticket,
1889         struct xlog_op_header   *ophdr,
1890         int                     space_available,
1891         int                     space_required,
1892         int                     *copy_off,
1893         int                     *copy_len,
1894         int                     *last_was_partial_copy,
1895         int                     *bytes_consumed)
1896 {
1897         int                     still_to_copy;
1898 
1899         still_to_copy = space_required - *bytes_consumed;
1900         *copy_off = *bytes_consumed;
1901 
1902         if (still_to_copy <= space_available) {
1903                 /* write of region completes here */
1904                 *copy_len = still_to_copy;
1905                 ophdr->oh_len = cpu_to_be32(*copy_len);
1906                 if (*last_was_partial_copy)
1907                         ophdr->oh_flags |= (XLOG_END_TRANS|XLOG_WAS_CONT_TRANS);
1908                 *last_was_partial_copy = 0;
1909                 *bytes_consumed = 0;
1910                 return 0;
1911         }
1912 
1913         /* partial write of region, needs extra log op header reservation */
1914         *copy_len = space_available;
1915         ophdr->oh_len = cpu_to_be32(*copy_len);
1916         ophdr->oh_flags |= XLOG_CONTINUE_TRANS;
1917         if (*last_was_partial_copy)
1918                 ophdr->oh_flags |= XLOG_WAS_CONT_TRANS;
1919         *bytes_consumed += *copy_len;
1920         (*last_was_partial_copy)++;
1921 
1922         /* account for new log op header */
1923         ticket->t_curr_res -= sizeof(struct xlog_op_header);
1924         ticket->t_res_num_ophdrs++;
1925 
1926         return sizeof(struct xlog_op_header);
1927 }
1928 
1929 static int
1930 xlog_write_copy_finish(
1931         struct xlog             *log,
1932         struct xlog_in_core     *iclog,
1933         uint                    flags,
1934         int                     *record_cnt,
1935         int                     *data_cnt,
1936         int                     *partial_copy,
1937         int                     *partial_copy_len,
1938         int                     log_offset,
1939         struct xlog_in_core     **commit_iclog)
1940 {
1941         if (*partial_copy) {
1942                 /*
1943                  * This iclog has already been marked WANT_SYNC by
1944                  * xlog_state_get_iclog_space.
1945                  */
1946                 xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt);
1947                 *record_cnt = 0;
1948                 *data_cnt = 0;
1949                 return xlog_state_release_iclog(log, iclog);
1950         }
1951 
1952         *partial_copy = 0;
1953         *partial_copy_len = 0;
1954 
1955         if (iclog->ic_size - log_offset <= sizeof(xlog_op_header_t)) {
1956                 /* no more space in this iclog - push it. */
1957                 xlog_state_finish_copy(log, iclog, *record_cnt, *data_cnt);
1958                 *record_cnt = 0;
1959                 *data_cnt = 0;
1960 
1961                 spin_lock(&log->l_icloglock);
1962                 xlog_state_want_sync(log, iclog);
1963                 spin_unlock(&log->l_icloglock);
1964 
1965                 if (!commit_iclog)
1966                         return xlog_state_release_iclog(log, iclog);
1967                 ASSERT(flags & XLOG_COMMIT_TRANS);
1968                 *commit_iclog = iclog;
1969         }
1970 
1971         return 0;
1972 }
1973 
1974 /*
1975  * Write some region out to in-core log
1976  *
1977  * This will be called when writing externally provided regions or when
1978  * writing out a commit record for a given transaction.
1979  *
1980  * General algorithm:
1981  *      1. Find total length of this write.  This may include adding to the
1982  *              lengths passed in.
1983  *      2. Check whether we violate the tickets reservation.
1984  *      3. While writing to this iclog
1985  *          A. Reserve as much space in this iclog as can get
1986  *          B. If this is first write, save away start lsn
1987  *          C. While writing this region:
1988  *              1. If first write of transaction, write start record
1989  *              2. Write log operation header (header per region)
1990  *              3. Find out if we can fit entire region into this iclog
1991  *              4. Potentially, verify destination memcpy ptr
1992  *              5. Memcpy (partial) region
1993  *              6. If partial copy, release iclog; otherwise, continue
1994  *                      copying more regions into current iclog
1995  *      4. Mark want sync bit (in simulation mode)
1996  *      5. Release iclog for potential flush to on-disk log.
1997  *
1998  * ERRORS:
1999  * 1.   Panic if reservation is overrun.  This should never happen since
2000  *      reservation amounts are generated internal to the filesystem.
2001  * NOTES:
2002  * 1. Tickets are single threaded data structures.
2003  * 2. The XLOG_END_TRANS & XLOG_CONTINUE_TRANS flags are passed down to the
2004  *      syncing routine.  When a single log_write region needs to span
2005  *      multiple in-core logs, the XLOG_CONTINUE_TRANS bit should be set
2006  *      on all log operation writes which don't contain the end of the
2007  *      region.  The XLOG_END_TRANS bit is used for the in-core log
2008  *      operation which contains the end of the continued log_write region.
2009  * 3. When xlog_state_get_iclog_space() grabs the rest of the current iclog,
2010  *      we don't really know exactly how much space will be used.  As a result,
2011  *      we don't update ic_offset until the end when we know exactly how many
2012  *      bytes have been written out.
2013  */
2014 int
2015 xlog_write(
2016         struct xlog             *log,
2017         struct xfs_log_vec      *log_vector,
2018         struct xlog_ticket      *ticket,
2019         xfs_lsn_t               *start_lsn,
2020         struct xlog_in_core     **commit_iclog,
2021         uint                    flags)
2022 {
2023         struct xlog_in_core     *iclog = NULL;
2024         struct xfs_log_iovec    *vecp;
2025         struct xfs_log_vec      *lv;
2026         int                     len;
2027         int                     index;
2028         int                     partial_copy = 0;
2029         int                     partial_copy_len = 0;
2030         int                     contwr = 0;
2031         int                     record_cnt = 0;
2032         int                     data_cnt = 0;
2033         int                     error;
2034 
2035         *start_lsn = 0;
2036 
2037         len = xlog_write_calc_vec_length(ticket, log_vector);
2038 
2039         /*
2040          * Region headers and bytes are already accounted for.
2041          * We only need to take into account start records and
2042          * split regions in this function.
2043          */
2044         if (ticket->t_flags & XLOG_TIC_INITED)
2045                 ticket->t_curr_res -= sizeof(xlog_op_header_t);
2046 
2047         /*
2048          * Commit record headers need to be accounted for. These
2049          * come in as separate writes so are easy to detect.
2050          */
2051         if (flags & (XLOG_COMMIT_TRANS | XLOG_UNMOUNT_TRANS))
2052                 ticket->t_curr_res -= sizeof(xlog_op_header_t);
2053 
2054         if (ticket->t_curr_res < 0)
2055                 xlog_print_tic_res(log->l_mp, ticket);
2056 
2057         index = 0;
2058         lv = log_vector;
2059         vecp = lv->lv_iovecp;
2060         while (lv && index < lv->lv_niovecs) {
2061                 void            *ptr;
2062                 int             log_offset;
2063 
2064                 error = xlog_state_get_iclog_space(log, len, &iclog, ticket,
2065                                                    &contwr, &log_offset);
2066                 if (error)
2067                         return error;
2068 
2069                 ASSERT(log_offset <= iclog->ic_size - 1);
2070                 ptr = iclog->ic_datap + log_offset;
2071 
2072                 /* start_lsn is the first lsn written to. That's all we need. */
2073                 if (!*start_lsn)
2074                         *start_lsn = be64_to_cpu(iclog->ic_header.h_lsn);
2075 
2076                 /*
2077                  * This loop writes out as many regions as can fit in the amount
2078                  * of space which was allocated by xlog_state_get_iclog_space().
2079                  */
2080                 while (lv && index < lv->lv_niovecs) {
2081                         struct xfs_log_iovec    *reg = &vecp[index];
2082                         struct xlog_op_header   *ophdr;
2083                         int                     start_rec_copy;
2084                         int                     copy_len;
2085                         int                     copy_off;
2086 
2087                         ASSERT(reg->i_len % sizeof(__int32_t) == 0);
2088                         ASSERT((unsigned long)ptr % sizeof(__int32_t) == 0);
2089 
2090                         start_rec_copy = xlog_write_start_rec(ptr, ticket);
2091                         if (start_rec_copy) {
2092                                 record_cnt++;
2093                                 xlog_write_adv_cnt(&ptr, &len, &log_offset,
2094                                                    start_rec_copy);
2095                         }
2096 
2097                         ophdr = xlog_write_setup_ophdr(log, ptr, ticket, flags);
2098                         if (!ophdr)
2099                                 return XFS_ERROR(EIO);
2100 
2101                         xlog_write_adv_cnt(&ptr, &len, &log_offset,
2102                                            sizeof(struct xlog_op_header));
2103 
2104                         len += xlog_write_setup_copy(ticket, ophdr,
2105                                                      iclog->ic_size-log_offset,
2106                                                      reg->i_len,
2107                                                      &copy_off, &copy_len,
2108                                                      &partial_copy,
2109                                                      &partial_copy_len);
2110                         xlog_verify_dest_ptr(log, ptr);
2111 
2112                         /* copy region */
2113                         ASSERT(copy_len >= 0);
2114                         memcpy(ptr, reg->i_addr + copy_off, copy_len);
2115                         xlog_write_adv_cnt(&ptr, &len, &log_offset, copy_len);
2116 
2117                         copy_len += start_rec_copy + sizeof(xlog_op_header_t);
2118                         record_cnt++;
2119                         data_cnt += contwr ? copy_len : 0;
2120 
2121                         error = xlog_write_copy_finish(log, iclog, flags,
2122                                                        &record_cnt, &data_cnt,
2123                                                        &partial_copy,
2124                                                        &partial_copy_len,
2125                                                        log_offset,
2126                                                        commit_iclog);
2127                         if (error)
2128                                 return error;
2129 
2130                         /*
2131                          * if we had a partial copy, we need to get more iclog
2132                          * space but we don't want to increment the region
2133                          * index because there is still more is this region to
2134                          * write.
2135                          *
2136                          * If we completed writing this region, and we flushed
2137                          * the iclog (indicated by resetting of the record
2138                          * count), then we also need to get more log space. If
2139                          * this was the last record, though, we are done and
2140                          * can just return.
2141                          */
2142                         if (partial_copy)
2143                                 break;
2144 
2145                         if (++index == lv->lv_niovecs) {
2146                                 lv = lv->lv_next;
2147                                 index = 0;
2148                                 if (lv)
2149                                         vecp = lv->lv_iovecp;
2150                         }
2151                         if (record_cnt == 0) {
2152                                 if (!lv)
2153                                         return 0;
2154                                 break;
2155                         }
2156                 }
2157         }
2158 
2159         ASSERT(len == 0);
2160 
2161         xlog_state_finish_copy(log, iclog, record_cnt, data_cnt);
2162         if (!commit_iclog)
2163                 return xlog_state_release_iclog(log, iclog);
2164 
2165         ASSERT(flags & XLOG_COMMIT_TRANS);
2166         *commit_iclog = iclog;
2167         return 0;
2168 }
2169 
2170 
2171 /*****************************************************************************
2172  *
2173  *              State Machine functions
2174  *
2175  *****************************************************************************
2176  */
2177 
2178 /* Clean iclogs starting from the head.  This ordering must be
2179  * maintained, so an iclog doesn't become ACTIVE beyond one that
2180  * is SYNCING.  This is also required to maintain the notion that we use
2181  * a ordered wait queue to hold off would be writers to the log when every
2182  * iclog is trying to sync to disk.
2183  *
2184  * State Change: DIRTY -> ACTIVE
2185  */
2186 STATIC void
2187 xlog_state_clean_log(
2188         struct xlog *log)
2189 {
2190         xlog_in_core_t  *iclog;
2191         int changed = 0;
2192 
2193         iclog = log->l_iclog;
2194         do {
2195                 if (iclog->ic_state == XLOG_STATE_DIRTY) {
2196                         iclog->ic_state = XLOG_STATE_ACTIVE;
2197                         iclog->ic_offset       = 0;
2198                         ASSERT(iclog->ic_callback == NULL);
2199                         /*
2200                          * If the number of ops in this iclog indicate it just
2201                          * contains the dummy transaction, we can
2202                          * change state into IDLE (the second time around).
2203                          * Otherwise we should change the state into
2204                          * NEED a dummy.
2205                          * We don't need to cover the dummy.
2206                          */
2207                         if (!changed &&
2208                            (be32_to_cpu(iclog->ic_header.h_num_logops) ==
2209                                         XLOG_COVER_OPS)) {
2210                                 changed = 1;
2211                         } else {
2212                                 /*
2213                                  * We have two dirty iclogs so start over
2214                                  * This could also be num of ops indicates
2215                                  * this is not the dummy going out.
2216                                  */
2217                                 changed = 2;
2218                         }
2219                         iclog->ic_header.h_num_logops = 0;
2220                         memset(iclog->ic_header.h_cycle_data, 0,
2221                               sizeof(iclog->ic_header.h_cycle_data));
2222                         iclog->ic_header.h_lsn = 0;
2223                 } else if (iclog->ic_state == XLOG_STATE_ACTIVE)
2224                         /* do nothing */;
2225                 else
2226                         break;  /* stop cleaning */
2227                 iclog = iclog->ic_next;
2228         } while (iclog != log->l_iclog);
2229 
2230         /* log is locked when we are called */
2231         /*
2232          * Change state for the dummy log recording.
2233          * We usually go to NEED. But we go to NEED2 if the changed indicates
2234          * we are done writing the dummy record.
2235          * If we are done with the second dummy recored (DONE2), then
2236          * we go to IDLE.
2237          */
2238         if (changed) {
2239                 switch (log->l_covered_state) {
2240                 case XLOG_STATE_COVER_IDLE:
2241                 case XLOG_STATE_COVER_NEED:
2242                 case XLOG_STATE_COVER_NEED2:
2243                         log->l_covered_state = XLOG_STATE_COVER_NEED;
2244                         break;
2245 
2246                 case XLOG_STATE_COVER_DONE:
2247                         if (changed == 1)
2248                                 log->l_covered_state = XLOG_STATE_COVER_NEED2;
2249                         else
2250                                 log->l_covered_state = XLOG_STATE_COVER_NEED;
2251                         break;
2252 
2253                 case XLOG_STATE_COVER_DONE2:
2254                         if (changed == 1)
2255                                 log->l_covered_state = XLOG_STATE_COVER_IDLE;
2256                         else
2257                                 log->l_covered_state = XLOG_STATE_COVER_NEED;
2258                         break;
2259 
2260                 default:
2261                         ASSERT(0);
2262                 }
2263         }
2264 }       /* xlog_state_clean_log */
2265 
2266 STATIC xfs_lsn_t
2267 xlog_get_lowest_lsn(
2268         struct xlog     *log)
2269 {
2270         xlog_in_core_t  *lsn_log;
2271         xfs_lsn_t       lowest_lsn, lsn;
2272 
2273         lsn_log = log->l_iclog;
2274         lowest_lsn = 0;
2275         do {
2276             if (!(lsn_log->ic_state & (XLOG_STATE_ACTIVE|XLOG_STATE_DIRTY))) {
2277                 lsn = be64_to_cpu(lsn_log->ic_header.h_lsn);
2278                 if ((lsn && !lowest_lsn) ||
2279                     (XFS_LSN_CMP(lsn, lowest_lsn) < 0)) {
2280                         lowest_lsn = lsn;
2281                 }
2282             }
2283             lsn_log = lsn_log->ic_next;
2284         } while (lsn_log != log->l_iclog);
2285         return lowest_lsn;
2286 }
2287 
2288 
2289 STATIC void
2290 xlog_state_do_callback(
2291         struct xlog             *log,
2292         int                     aborted,
2293         struct xlog_in_core     *ciclog)
2294 {
2295         xlog_in_core_t     *iclog;
2296         xlog_in_core_t     *first_iclog;        /* used to know when we've
2297                                                  * processed all iclogs once */
2298         xfs_log_callback_t *cb, *cb_next;
2299         int                flushcnt = 0;
2300         xfs_lsn_t          lowest_lsn;
2301         int                ioerrors;    /* counter: iclogs with errors */
2302         int                loopdidcallbacks; /* flag: inner loop did callbacks*/
2303         int                funcdidcallbacks; /* flag: function did callbacks */
2304         int                repeats;     /* for issuing console warnings if
2305                                          * looping too many times */
2306         int                wake = 0;
2307 
2308         spin_lock(&log->l_icloglock);
2309         first_iclog = iclog = log->l_iclog;
2310         ioerrors = 0;
2311         funcdidcallbacks = 0;
2312         repeats = 0;
2313 
2314         do {
2315                 /*
2316                  * Scan all iclogs starting with the one pointed to by the
2317                  * log.  Reset this starting point each time the log is
2318                  * unlocked (during callbacks).
2319                  *
2320                  * Keep looping through iclogs until one full pass is made
2321                  * without running any callbacks.
2322                  */
2323                 first_iclog = log->l_iclog;
2324                 iclog = log->l_iclog;
2325                 loopdidcallbacks = 0;
2326                 repeats++;
2327 
2328                 do {
2329 
2330                         /* skip all iclogs in the ACTIVE & DIRTY states */
2331                         if (iclog->ic_state &
2332                             (XLOG_STATE_ACTIVE|XLOG_STATE_DIRTY)) {
2333                                 iclog = iclog->ic_next;
2334                                 continue;
2335                         }
2336 
2337                         /*
2338                          * Between marking a filesystem SHUTDOWN and stopping
2339                          * the log, we do flush all iclogs to disk (if there
2340                          * wasn't a log I/O error). So, we do want things to
2341                          * go smoothly in case of just a SHUTDOWN  w/o a
2342                          * LOG_IO_ERROR.
2343                          */
2344                         if (!(iclog->ic_state & XLOG_STATE_IOERROR)) {
2345                                 /*
2346                                  * Can only perform callbacks in order.  Since
2347                                  * this iclog is not in the DONE_SYNC/
2348                                  * DO_CALLBACK state, we skip the rest and
2349                                  * just try to clean up.  If we set our iclog
2350                                  * to DO_CALLBACK, we will not process it when
2351                                  * we retry since a previous iclog is in the
2352                                  * CALLBACK and the state cannot change since
2353                                  * we are holding the l_icloglock.
2354                                  */
2355                                 if (!(iclog->ic_state &
2356                                         (XLOG_STATE_DONE_SYNC |
2357                                                  XLOG_STATE_DO_CALLBACK))) {
2358                                         if (ciclog && (ciclog->ic_state ==
2359                                                         XLOG_STATE_DONE_SYNC)) {
2360                                                 ciclog->ic_state = XLOG_STATE_DO_CALLBACK;
2361                                         }
2362                                         break;
2363                                 }
2364                                 /*
2365                                  * We now have an iclog that is in either the
2366                                  * DO_CALLBACK or DONE_SYNC states. The other
2367                                  * states (WANT_SYNC, SYNCING, or CALLBACK were
2368                                  * caught by the above if and are going to
2369                                  * clean (i.e. we aren't doing their callbacks)
2370                                  * see the above if.
2371                                  */
2372 
2373                                 /*
2374                                  * We will do one more check here to see if we
2375                                  * have chased our tail around.
2376                                  */
2377 
2378                                 lowest_lsn = xlog_get_lowest_lsn(log);
2379                                 if (lowest_lsn &&
2380                                     XFS_LSN_CMP(lowest_lsn,
2381                                                 be64_to_cpu(iclog->ic_header.h_lsn)) < 0) {
2382                                         iclog = iclog->ic_next;
2383                                         continue; /* Leave this iclog for
2384                                                    * another thread */
2385                                 }
2386 
2387                                 iclog->ic_state = XLOG_STATE_CALLBACK;
2388 
2389 
2390                                 /*
2391                                  * Completion of a iclog IO does not imply that
2392                                  * a transaction has completed, as transactions
2393                                  * can be large enough to span many iclogs. We
2394                                  * cannot change the tail of the log half way
2395                                  * through a transaction as this may be the only
2396                                  * transaction in the log and moving th etail to
2397                                  * point to the middle of it will prevent
2398                                  * recovery from finding the start of the
2399                                  * transaction. Hence we should only update the
2400                                  * last_sync_lsn if this iclog contains
2401                                  * transaction completion callbacks on it.
2402                                  *
2403                                  * We have to do this before we drop the
2404                                  * icloglock to ensure we are the only one that
2405                                  * can update it.
2406                                  */
2407                                 ASSERT(XFS_LSN_CMP(atomic64_read(&log->l_last_sync_lsn),
2408                                         be64_to_cpu(iclog->ic_header.h_lsn)) <= 0);
2409                                 if (iclog->ic_callback)
2410                                         atomic64_set(&log->l_last_sync_lsn,
2411                                                 be64_to_cpu(iclog->ic_header.h_lsn));
2412 
2413                         } else
2414                                 ioerrors++;
2415 
2416                         spin_unlock(&log->l_icloglock);
2417 
2418                         /*
2419                          * Keep processing entries in the callback list until
2420                          * we come around and it is empty.  We need to
2421                          * atomically see that the list is empty and change the
2422                          * state to DIRTY so that we don't miss any more
2423                          * callbacks being added.
2424                          */
2425                         spin_lock(&iclog->ic_callback_lock);
2426                         cb = iclog->ic_callback;
2427                         while (cb) {
2428                                 iclog->ic_callback_tail = &(iclog->ic_callback);
2429                                 iclog->ic_callback = NULL;
2430                                 spin_unlock(&iclog->ic_callback_lock);
2431 
2432                                 /* perform callbacks in the order given */
2433                                 for (; cb; cb = cb_next) {
2434                                         cb_next = cb->cb_next;
2435                                         cb->cb_func(cb->cb_arg, aborted);
2436                                 }
2437                                 spin_lock(&iclog->ic_callback_lock);
2438                                 cb = iclog->ic_callback;
2439                         }
2440 
2441                         loopdidcallbacks++;
2442                         funcdidcallbacks++;
2443 
2444                         spin_lock(&log->l_icloglock);
2445                         ASSERT(iclog->ic_callback == NULL);
2446                         spin_unlock(&iclog->ic_callback_lock);
2447                         if (!(iclog->ic_state & XLOG_STATE_IOERROR))
2448                                 iclog->ic_state = XLOG_STATE_DIRTY;
2449 
2450                         /*
2451                          * Transition from DIRTY to ACTIVE if applicable.
2452                          * NOP if STATE_IOERROR.
2453                          */
2454                         xlog_state_clean_log(log);
2455 
2456                         /* wake up threads waiting in xfs_log_force() */
2457                         wake_up_all(&iclog->ic_force_wait);
2458 
2459                         iclog = iclog->ic_next;
2460                 } while (first_iclog != iclog);
2461 
2462                 if (repeats > 5000) {
2463                         flushcnt += repeats;
2464                         repeats = 0;
2465                         xfs_warn(log->l_mp,
2466                                 "%s: possible infinite loop (%d iterations)",
2467                                 __func__, flushcnt);
2468                 }
2469         } while (!ioerrors && loopdidcallbacks);
2470 
2471         /*
2472          * make one last gasp attempt to see if iclogs are being left in
2473          * limbo..
2474          */
2475 #ifdef DEBUG
2476         if (funcdidcallbacks) {
2477                 first_iclog = iclog = log->l_iclog;
2478                 do {
2479                         ASSERT(iclog->ic_state != XLOG_STATE_DO_CALLBACK);
2480                         /*
2481                          * Terminate the loop if iclogs are found in states
2482                          * which will cause other threads to clean up iclogs.
2483                          *
2484                          * SYNCING - i/o completion will go through logs
2485                          * DONE_SYNC - interrupt thread should be waiting for
2486                          *              l_icloglock
2487                          * IOERROR - give up hope all ye who enter here
2488                          */
2489                         if (iclog->ic_state == XLOG_STATE_WANT_SYNC ||
2490                             iclog->ic_state == XLOG_STATE_SYNCING ||
2491                             iclog->ic_state == XLOG_STATE_DONE_SYNC ||
2492                             iclog->ic_state == XLOG_STATE_IOERROR )
2493                                 break;
2494                         iclog = iclog->ic_next;
2495                 } while (first_iclog != iclog);
2496         }
2497 #endif
2498 
2499         if (log->l_iclog->ic_state & (XLOG_STATE_ACTIVE|XLOG_STATE_IOERROR))
2500                 wake = 1;
2501         spin_unlock(&log->l_icloglock);
2502 
2503         if (wake)
2504                 wake_up_all(&log->l_flush_wait);
2505 }
2506 
2507 
2508 /*
2509  * Finish transitioning this iclog to the dirty state.
2510  *
2511  * Make sure that we completely execute this routine only when this is
2512  * the last call to the iclog.  There is a good chance that iclog flushes,
2513  * when we reach the end of the physical log, get turned into 2 separate
2514  * calls to bwrite.  Hence, one iclog flush could generate two calls to this
2515  * routine.  By using the reference count bwritecnt, we guarantee that only
2516  * the second completion goes through.
2517  *
2518  * Callbacks could take time, so they are done outside the scope of the
2519  * global state machine log lock.
2520  */
2521 STATIC void
2522 xlog_state_done_syncing(
2523         xlog_in_core_t  *iclog,
2524         int             aborted)
2525 {
2526         struct xlog        *log = iclog->ic_log;
2527 
2528         spin_lock(&log->l_icloglock);
2529 
2530         ASSERT(iclog->ic_state == XLOG_STATE_SYNCING ||
2531                iclog->ic_state == XLOG_STATE_IOERROR);
2532         ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
2533         ASSERT(iclog->ic_bwritecnt == 1 || iclog->ic_bwritecnt == 2);
2534 
2535 
2536         /*
2537          * If we got an error, either on the first buffer, or in the case of
2538          * split log writes, on the second, we mark ALL iclogs STATE_IOERROR,
2539          * and none should ever be attempted to be written to disk
2540          * again.
2541          */
2542         if (iclog->ic_state != XLOG_STATE_IOERROR) {
2543                 if (--iclog->ic_bwritecnt == 1) {
2544                         spin_unlock(&log->l_icloglock);
2545                         return;
2546                 }
2547                 iclog->ic_state = XLOG_STATE_DONE_SYNC;
2548         }
2549 
2550         /*
2551          * Someone could be sleeping prior to writing out the next
2552          * iclog buffer, we wake them all, one will get to do the
2553          * I/O, the others get to wait for the result.
2554          */
2555         wake_up_all(&iclog->ic_write_wait);
2556         spin_unlock(&log->l_icloglock);
2557         xlog_state_do_callback(log, aborted, iclog);    /* also cleans log */
2558 }       /* xlog_state_done_syncing */
2559 
2560 
2561 /*
2562  * If the head of the in-core log ring is not (ACTIVE or DIRTY), then we must
2563  * sleep.  We wait on the flush queue on the head iclog as that should be
2564  * the first iclog to complete flushing. Hence if all iclogs are syncing,
2565  * we will wait here and all new writes will sleep until a sync completes.
2566  *
2567  * The in-core logs are used in a circular fashion. They are not used
2568  * out-of-order even when an iclog past the head is free.
2569  *
2570  * return:
2571  *      * log_offset where xlog_write() can start writing into the in-core
2572  *              log's data space.
2573  *      * in-core log pointer to which xlog_write() should write.
2574  *      * boolean indicating this is a continued write to an in-core log.
2575  *              If this is the last write, then the in-core log's offset field
2576  *              needs to be incremented, depending on the amount of data which
2577  *              is copied.
2578  */
2579 STATIC int
2580 xlog_state_get_iclog_space(
2581         struct xlog             *log,
2582         int                     len,
2583         struct xlog_in_core     **iclogp,
2584         struct xlog_ticket      *ticket,
2585         int                     *continued_write,
2586         int                     *logoffsetp)
2587 {
2588         int               log_offset;
2589         xlog_rec_header_t *head;
2590         xlog_in_core_t    *iclog;
2591         int               error;
2592 
2593 restart:
2594         spin_lock(&log->l_icloglock);
2595         if (XLOG_FORCED_SHUTDOWN(log)) {
2596                 spin_unlock(&log->l_icloglock);
2597                 return XFS_ERROR(EIO);
2598         }
2599 
2600         iclog = log->l_iclog;
2601         if (iclog->ic_state != XLOG_STATE_ACTIVE) {
2602                 XFS_STATS_INC(xs_log_noiclogs);
2603 
2604                 /* Wait for log writes to have flushed */
2605                 xlog_wait(&log->l_flush_wait, &log->l_icloglock);
2606                 goto restart;
2607         }
2608 
2609         head = &iclog->ic_header;
2610 
2611         atomic_inc(&iclog->ic_refcnt);  /* prevents sync */
2612         log_offset = iclog->ic_offset;
2613 
2614         /* On the 1st write to an iclog, figure out lsn.  This works
2615          * if iclogs marked XLOG_STATE_WANT_SYNC always write out what they are
2616          * committing to.  If the offset is set, that's how many blocks
2617          * must be written.
2618          */
2619         if (log_offset == 0) {
2620                 ticket->t_curr_res -= log->l_iclog_hsize;
2621                 xlog_tic_add_region(ticket,
2622                                     log->l_iclog_hsize,
2623                                     XLOG_REG_TYPE_LRHEADER);
2624                 head->h_cycle = cpu_to_be32(log->l_curr_cycle);
2625                 head->h_lsn = cpu_to_be64(
2626                         xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block));
2627                 ASSERT(log->l_curr_block >= 0);
2628         }
2629 
2630         /* If there is enough room to write everything, then do it.  Otherwise,
2631          * claim the rest of the region and make sure the XLOG_STATE_WANT_SYNC
2632          * bit is on, so this will get flushed out.  Don't update ic_offset
2633          * until you know exactly how many bytes get copied.  Therefore, wait
2634          * until later to update ic_offset.
2635          *
2636          * xlog_write() algorithm assumes that at least 2 xlog_op_header_t's
2637          * can fit into remaining data section.
2638          */
2639         if (iclog->ic_size - iclog->ic_offset < 2*sizeof(xlog_op_header_t)) {
2640                 xlog_state_switch_iclogs(log, iclog, iclog->ic_size);
2641 
2642                 /*
2643                  * If I'm the only one writing to this iclog, sync it to disk.
2644                  * We need to do an atomic compare and decrement here to avoid
2645                  * racing with concurrent atomic_dec_and_lock() calls in
2646                  * xlog_state_release_iclog() when there is more than one
2647                  * reference to the iclog.
2648                  */
2649                 if (!atomic_add_unless(&iclog->ic_refcnt, -1, 1)) {
2650                         /* we are the only one */
2651                         spin_unlock(&log->l_icloglock);
2652                         error = xlog_state_release_iclog(log, iclog);
2653                         if (error)
2654                                 return error;
2655                 } else {
2656                         spin_unlock(&log->l_icloglock);
2657                 }
2658                 goto restart;
2659         }
2660 
2661         /* Do we have enough room to write the full amount in the remainder
2662          * of this iclog?  Or must we continue a write on the next iclog and
2663          * mark this iclog as completely taken?  In the case where we switch
2664          * iclogs (to mark it taken), this particular iclog will release/sync
2665          * to disk in xlog_write().
2666          */
2667         if (len <= iclog->ic_size - iclog->ic_offset) {
2668                 *continued_write = 0;
2669                 iclog->ic_offset += len;
2670         } else {
2671                 *continued_write = 1;
2672                 xlog_state_switch_iclogs(log, iclog, iclog->ic_size);
2673         }
2674         *iclogp = iclog;
2675 
2676         ASSERT(iclog->ic_offset <= iclog->ic_size);
2677         spin_unlock(&log->l_icloglock);
2678 
2679         *logoffsetp = log_offset;
2680         return 0;
2681 }       /* xlog_state_get_iclog_space */
2682 
2683 /* The first cnt-1 times through here we don't need to
2684  * move the grant write head because the permanent
2685  * reservation has reserved cnt times the unit amount.
2686  * Release part of current permanent unit reservation and
2687  * reset current reservation to be one units worth.  Also
2688  * move grant reservation head forward.
2689  */
2690 STATIC void
2691 xlog_regrant_reserve_log_space(
2692         struct xlog             *log,
2693         struct xlog_ticket      *ticket)
2694 {
2695         trace_xfs_log_regrant_reserve_enter(log, ticket);
2696 
2697         if (ticket->t_cnt > 0)
2698                 ticket->t_cnt--;
2699 
2700         xlog_grant_sub_space(log, &log->l_reserve_head.grant,
2701                                         ticket->t_curr_res);
2702         xlog_grant_sub_space(log, &log->l_write_head.grant,
2703                                         ticket->t_curr_res);
2704         ticket->t_curr_res = ticket->t_unit_res;
2705         xlog_tic_reset_res(ticket);
2706 
2707         trace_xfs_log_regrant_reserve_sub(log, ticket);
2708 
2709         /* just return if we still have some of the pre-reserved space */
2710         if (ticket->t_cnt > 0)
2711                 return;
2712 
2713         xlog_grant_add_space(log, &log->l_reserve_head.grant,
2714                                         ticket->t_unit_res);
2715 
2716         trace_xfs_log_regrant_reserve_exit(log, ticket);
2717 
2718         ticket->t_curr_res = ticket->t_unit_res;
2719         xlog_tic_reset_res(ticket);
2720 }       /* xlog_regrant_reserve_log_space */
2721 
2722 
2723 /*
2724  * Give back the space left from a reservation.
2725  *
2726  * All the information we need to make a correct determination of space left
2727  * is present.  For non-permanent reservations, things are quite easy.  The
2728  * count should have been decremented to zero.  We only need to deal with the
2729  * space remaining in the current reservation part of the ticket.  If the
2730  * ticket contains a permanent reservation, there may be left over space which
2731  * needs to be released.  A count of N means that N-1 refills of the current
2732  * reservation can be done before we need to ask for more space.  The first
2733  * one goes to fill up the first current reservation.  Once we run out of
2734  * space, the count will stay at zero and the only space remaining will be
2735  * in the current reservation field.
2736  */
2737 STATIC void
2738 xlog_ungrant_log_space(
2739         struct xlog             *log,
2740         struct xlog_ticket      *ticket)
2741 {
2742         int     bytes;
2743 
2744         if (ticket->t_cnt > 0)
2745                 ticket->t_cnt--;
2746 
2747         trace_xfs_log_ungrant_enter(log, ticket);
2748         trace_xfs_log_ungrant_sub(log, ticket);
2749 
2750         /*
2751          * If this is a permanent reservation ticket, we may be able to free
2752          * up more space based on the remaining count.
2753          */
2754         bytes = ticket->t_curr_res;
2755         if (ticket->t_cnt > 0) {
2756                 ASSERT(ticket->t_flags & XLOG_TIC_PERM_RESERV);
2757                 bytes += ticket->t_unit_res*ticket->t_cnt;
2758         }
2759 
2760         xlog_grant_sub_space(log, &log->l_reserve_head.grant, bytes);
2761         xlog_grant_sub_space(log, &log->l_write_head.grant, bytes);
2762 
2763         trace_xfs_log_ungrant_exit(log, ticket);
2764 
2765         xfs_log_space_wake(log->l_mp);
2766 }
2767 
2768 /*
2769  * Flush iclog to disk if this is the last reference to the given iclog and
2770  * the WANT_SYNC bit is set.
2771  *
2772  * When this function is entered, the iclog is not necessarily in the
2773  * WANT_SYNC state.  It may be sitting around waiting to get filled.
2774  *
2775  *
2776  */
2777 STATIC int
2778 xlog_state_release_iclog(
2779         struct xlog             *log,
2780         struct xlog_in_core     *iclog)
2781 {
2782         int             sync = 0;       /* do we sync? */
2783 
2784         if (iclog->ic_state & XLOG_STATE_IOERROR)
2785                 return XFS_ERROR(EIO);
2786 
2787         ASSERT(atomic_read(&iclog->ic_refcnt) > 0);
2788         if (!atomic_dec_and_lock(&iclog->ic_refcnt, &log->l_icloglock))
2789                 return 0;
2790 
2791         if (iclog->ic_state & XLOG_STATE_IOERROR) {
2792                 spin_unlock(&log->l_icloglock);
2793                 return XFS_ERROR(EIO);
2794         }
2795         ASSERT(iclog->ic_state == XLOG_STATE_ACTIVE ||
2796                iclog->ic_state == XLOG_STATE_WANT_SYNC);
2797 
2798         if (iclog->ic_state == XLOG_STATE_WANT_SYNC) {
2799                 /* update tail before writing to iclog */
2800                 xfs_lsn_t tail_lsn = xlog_assign_tail_lsn(log->l_mp);
2801                 sync++;
2802                 iclog->ic_state = XLOG_STATE_SYNCING;
2803                 iclog->ic_header.h_tail_lsn = cpu_to_be64(tail_lsn);
2804                 xlog_verify_tail_lsn(log, iclog, tail_lsn);
2805                 /* cycle incremented when incrementing curr_block */
2806         }
2807         spin_unlock(&log->l_icloglock);
2808 
2809         /*
2810          * We let the log lock go, so it's possible that we hit a log I/O
2811          * error or some other SHUTDOWN condition that marks the iclog
2812          * as XLOG_STATE_IOERROR before the bwrite. However, we know that
2813          * this iclog has consistent data, so we ignore IOERROR
2814          * flags after this point.
2815          */
2816         if (sync)
2817                 return xlog_sync(log, iclog);
2818         return 0;
2819 }       /* xlog_state_release_iclog */
2820 
2821 
2822 /*
2823  * This routine will mark the current iclog in the ring as WANT_SYNC
2824  * and move the current iclog pointer to the next iclog in the ring.
2825  * When this routine is called from xlog_state_get_iclog_space(), the
2826  * exact size of the iclog has not yet been determined.  All we know is
2827  * that every data block.  We have run out of space in this log record.
2828  */
2829 STATIC void
2830 xlog_state_switch_iclogs(
2831         struct xlog             *log,
2832         struct xlog_in_core     *iclog,
2833         int                     eventual_size)
2834 {
2835         ASSERT(iclog->ic_state == XLOG_STATE_ACTIVE);
2836         if (!eventual_size)
2837                 eventual_size = iclog->ic_offset;
2838         iclog->ic_state = XLOG_STATE_WANT_SYNC;
2839         iclog->ic_header.h_prev_block = cpu_to_be32(log->l_prev_block);
2840         log->l_prev_block = log->l_curr_block;
2841         log->l_prev_cycle = log->l_curr_cycle;
2842 
2843         /* roll log?: ic_offset changed later */
2844         log->l_curr_block += BTOBB(eventual_size)+BTOBB(log->l_iclog_hsize);
2845 
2846         /* Round up to next log-sunit */
2847         if (xfs_sb_version_haslogv2(&log->l_mp->m_sb) &&
2848             log->l_mp->m_sb.sb_logsunit > 1) {
2849                 __uint32_t sunit_bb = BTOBB(log->l_mp->m_sb.sb_logsunit);
2850                 log->l_curr_block = roundup(log->l_curr_block, sunit_bb);
2851         }
2852 
2853         if (log->l_curr_block >= log->l_logBBsize) {
2854                 log->l_curr_cycle++;
2855                 if (log->l_curr_cycle == XLOG_HEADER_MAGIC_NUM)
2856                         log->l_curr_cycle++;
2857                 log->l_curr_block -= log->l_logBBsize;
2858                 ASSERT(log->l_curr_block >= 0);
2859         }
2860         ASSERT(iclog == log->l_iclog);
2861         log->l_iclog = iclog->ic_next;
2862 }       /* xlog_state_switch_iclogs */
2863 
2864 /*
2865  * Write out all data in the in-core log as of this exact moment in time.
2866  *
2867  * Data may be written to the in-core log during this call.  However,
2868  * we don't guarantee this data will be written out.  A change from past
2869  * implementation means this routine will *not* write out zero length LRs.
2870  *
2871  * Basically, we try and perform an intelligent scan of the in-core logs.
2872  * If we determine there is no flushable data, we just return.  There is no
2873  * flushable data if:
2874  *
2875  *      1. the current iclog is active and has no data; the previous iclog
2876  *              is in the active or dirty state.
2877  *      2. the current iclog is drity, and the previous iclog is in the
2878  *              active or dirty state.
2879  *
2880  * We may sleep if:
2881  *
2882  *      1. the current iclog is not in the active nor dirty state.
2883  *      2. the current iclog dirty, and the previous iclog is not in the
2884  *              active nor dirty state.
2885  *      3. the current iclog is active, and there is another thread writing
2886  *              to this particular iclog.
2887  *      4. a) the current iclog is active and has no other writers
2888  *         b) when we return from flushing out this iclog, it is still
2889  *              not in the active nor dirty state.
2890  */
2891 int
2892 _xfs_log_force(
2893         struct xfs_mount        *mp,
2894         uint                    flags,
2895         int                     *log_flushed)
2896 {
2897         struct xlog             *log = mp->m_log;
2898         struct xlog_in_core     *iclog;
2899         xfs_lsn_t               lsn;
2900 
2901         XFS_STATS_INC(xs_log_force);
2902 
2903         xlog_cil_force(log);
2904 
2905         spin_lock(&log->l_icloglock);
2906 
2907         iclog = log->l_iclog;
2908         if (iclog->ic_state & XLOG_STATE_IOERROR) {
2909                 spin_unlock(&log->l_icloglock);
2910                 return XFS_ERROR(EIO);
2911         }
2912 
2913         /* If the head iclog is not active nor dirty, we just attach
2914          * ourselves to the head and go to sleep.
2915          */
2916         if (iclog->ic_state == XLOG_STATE_ACTIVE ||
2917             iclog->ic_state == XLOG_STATE_DIRTY) {
2918                 /*
2919                  * If the head is dirty or (active and empty), then
2920                  * we need to look at the previous iclog.  If the previous
2921                  * iclog is active or dirty we are done.  There is nothing
2922                  * to sync out.  Otherwise, we attach ourselves to the
2923                  * previous iclog and go to sleep.
2924                  */
2925                 if (iclog->ic_state == XLOG_STATE_DIRTY ||
2926                     (atomic_read(&iclog->ic_refcnt) == 0
2927                      && iclog->ic_offset == 0)) {
2928                         iclog = iclog->ic_prev;
2929                         if (iclog->ic_state == XLOG_STATE_ACTIVE ||
2930                             iclog->ic_state == XLOG_STATE_DIRTY)
2931                                 goto no_sleep;
2932                         else
2933                                 goto maybe_sleep;
2934                 } else {
2935                         if (atomic_read(&iclog->ic_refcnt) == 0) {
2936                                 /* We are the only one with access to this
2937                                  * iclog.  Flush it out now.  There should
2938                                  * be a roundoff of zero to show that someone
2939                                  * has already taken care of the roundoff from
2940                                  * the previous sync.
2941                                  */
2942                                 atomic_inc(&iclog->ic_refcnt);
2943                                 lsn = be64_to_cpu(iclog->ic_header.h_lsn);
2944                                 xlog_state_switch_iclogs(log, iclog, 0);
2945                                 spin_unlock(&log->l_icloglock);
2946 
2947                                 if (xlog_state_release_iclog(log, iclog))
2948                                         return XFS_ERROR(EIO);
2949 
2950                                 if (log_flushed)
2951                                         *log_flushed = 1;
2952                                 spin_lock(&log->l_icloglock);
2953                                 if (be64_to_cpu(iclog->ic_header.h_lsn) == lsn &&
2954                                     iclog->ic_state != XLOG_STATE_DIRTY)
2955                                         goto maybe_sleep;
2956                                 else
2957                                         goto no_sleep;
2958                         } else {
2959                                 /* Someone else is writing to this iclog.
2960                                  * Use its call to flush out the data.  However,
2961                                  * the other thread may not force out this LR,
2962                                  * so we mark it WANT_SYNC.
2963                                  */
2964                                 xlog_state_switch_iclogs(log, iclog, 0);
2965                                 goto maybe_sleep;
2966                         }
2967                 }
2968         }
2969 
2970         /* By the time we come around again, the iclog could've been filled
2971          * which would give it another lsn.  If we have a new lsn, just
2972          * return because the relevant data has been flushed.
2973          */
2974 maybe_sleep:
2975         if (flags & XFS_LOG_SYNC) {
2976                 /*
2977                  * We must check if we're shutting down here, before
2978                  * we wait, while we're holding the l_icloglock.
2979                  * Then we check again after waking up, in case our
2980                  * sleep was disturbed by a bad news.
2981                  */
2982                 if (iclog->ic_state & XLOG_STATE_IOERROR) {
2983                         spin_unlock(&log->l_icloglock);
2984                         return XFS_ERROR(EIO);
2985                 }
2986                 XFS_STATS_INC(xs_log_force_sleep);
2987                 xlog_wait(&iclog->ic_force_wait, &log->l_icloglock);
2988                 /*
2989                  * No need to grab the log lock here since we're
2990                  * only deciding whether or not to return EIO
2991                  * and the memory read should be atomic.
2992                  */
2993                 if (iclog->ic_state & XLOG_STATE_IOERROR)
2994                         return XFS_ERROR(EIO);
2995                 if (log_flushed)
2996                         *log_flushed = 1;
2997         } else {
2998 
2999 no_sleep:
3000                 spin_unlock(&log->l_icloglock);
3001         }
3002         return 0;
3003 }
3004 
3005 /*
3006  * Wrapper for _xfs_log_force(), to be used when caller doesn't care
3007  * about errors or whether the log was flushed or not. This is the normal
3008  * interface to use when trying to unpin items or move the log forward.
3009  */
3010 void
3011 xfs_log_force(
3012         xfs_mount_t     *mp,
3013         uint            flags)
3014 {
3015         int     error;
3016 
3017         trace_xfs_log_force(mp, 0);
3018         error = _xfs_log_force(mp, flags, NULL);
3019         if (error)
3020                 xfs_warn(mp, "%s: error %d returned.", __func__, error);
3021 }
3022 
3023 /*
3024  * Force the in-core log to disk for a specific LSN.
3025  *
3026  * Find in-core log with lsn.
3027  *      If it is in the DIRTY state, just return.
3028  *      If it is in the ACTIVE state, move the in-core log into the WANT_SYNC
3029  *              state and go to sleep or return.
3030  *      If it is in any other state, go to sleep or return.
3031  *
3032  * Synchronous forces are implemented with a signal variable. All callers
3033  * to force a given lsn to disk will wait on a the sv attached to the
3034  * specific in-core log.  When given in-core log finally completes its
3035  * write to disk, that thread will wake up all threads waiting on the
3036  * sv.
3037  */
3038 int
3039 _xfs_log_force_lsn(
3040         struct xfs_mount        *mp,
3041         xfs_lsn_t               lsn,
3042         uint                    flags,
3043         int                     *log_flushed)
3044 {
3045         struct xlog             *log = mp->m_log;
3046         struct xlog_in_core     *iclog;
3047         int                     already_slept = 0;
3048 
3049         ASSERT(lsn != 0);
3050 
3051         XFS_STATS_INC(xs_log_force);
3052 
3053         lsn = xlog_cil_force_lsn(log, lsn);
3054         if (lsn == NULLCOMMITLSN)
3055                 return 0;
3056 
3057 try_again:
3058         spin_lock(&log->l_icloglock);
3059         iclog = log->l_iclog;
3060         if (iclog->ic_state & XLOG_STATE_IOERROR) {
3061                 spin_unlock(&log->l_icloglock);
3062                 return XFS_ERROR(EIO);
3063         }
3064 
3065         do {
3066                 if (be64_to_cpu(iclog->ic_header.h_lsn) != lsn) {
3067                         iclog = iclog->ic_next;
3068                         continue;
3069                 }
3070 
3071                 if (iclog->ic_state == XLOG_STATE_DIRTY) {
3072                         spin_unlock(&log->l_icloglock);
3073                         return 0;
3074                 }
3075 
3076                 if (iclog->ic_state == XLOG_STATE_ACTIVE) {
3077                         /*
3078                          * We sleep here if we haven't already slept (e.g.
3079                          * this is the first time we've looked at the correct
3080                          * iclog buf) and the buffer before us is going to
3081                          * be sync'ed. The reason for this is that if we
3082                          * are doing sync transactions here, by waiting for
3083                          * the previous I/O to complete, we can allow a few
3084                          * more transactions into this iclog before we close
3085                          * it down.
3086                          *
3087                          * Otherwise, we mark the buffer WANT_SYNC, and bump
3088                          * up the refcnt so we can release the log (which
3089                          * drops the ref count).  The state switch keeps new
3090                          * transaction commits from using this buffer.  When
3091                          * the current commits finish writing into the buffer,
3092                          * the refcount will drop to zero and the buffer will
3093                          * go out then.
3094                          */
3095                         if (!already_slept &&
3096                             (iclog->ic_prev->ic_state &
3097                              (XLOG_STATE_WANT_SYNC | XLOG_STATE_SYNCING))) {
3098                                 ASSERT(!(iclog->ic_state & XLOG_STATE_IOERROR));
3099 
3100                                 XFS_STATS_INC(xs_log_force_sleep);
3101 
3102                                 xlog_wait(&iclog->ic_prev->ic_write_wait,
3103                                                         &log->l_icloglock);
3104                                 if (log_flushed)
3105                                         *log_flushed = 1;
3106                                 already_slept = 1;
3107                                 goto try_again;
3108                         }
3109                         atomic_inc(&iclog->ic_refcnt);
3110                         xlog_state_switch_iclogs(log, iclog, 0);
3111                         spin_unlock(&log->l_icloglock);
3112                         if (xlog_state_release_iclog(log, iclog))
3113                                 return XFS_ERROR(EIO);
3114                         if (log_flushed)
3115                                 *log_flushed = 1;
3116                         spin_lock(&log->l_icloglock);
3117                 }
3118 
3119                 if ((flags & XFS_LOG_SYNC) && /* sleep */
3120                     !(iclog->ic_state &
3121                       (XLOG_STATE_ACTIVE | XLOG_STATE_DIRTY))) {
3122                         /*
3123                          * Don't wait on completion if we know that we've
3124                          * gotten a log write error.
3125                          */
3126                         if (iclog->ic_state & XLOG_STATE_IOERROR) {
3127                                 spin_unlock(&log->l_icloglock);
3128                                 return XFS_ERROR(EIO);
3129                         }
3130                         XFS_STATS_INC(xs_log_force_sleep);
3131                         xlog_wait(&iclog->ic_force_wait, &log->l_icloglock);
3132                         /*
3133                          * No need to grab the log lock here since we're
3134                          * only deciding whether or not to return EIO
3135                          * and the memory read should be atomic.
3136                          */
3137                         if (iclog->ic_state & XLOG_STATE_IOERROR)
3138                                 return XFS_ERROR(EIO);
3139 
3140                         if (log_flushed)
3141                                 *log_flushed = 1;
3142                 } else {                /* just return */
3143                         spin_unlock(&log->l_icloglock);
3144                 }
3145 
3146                 return 0;
3147         } while (iclog != log->l_iclog);
3148 
3149         spin_unlock(&log->l_icloglock);
3150         return 0;
3151 }
3152 
3153 /*
3154  * Wrapper for _xfs_log_force_lsn(), to be used when caller doesn't care
3155  * about errors or whether the log was flushed or not. This is the normal
3156  * interface to use when trying to unpin items or move the log forward.
3157  */
3158 void
3159 xfs_log_force_lsn(
3160         xfs_mount_t     *mp,
3161         xfs_lsn_t       lsn,
3162         uint            flags)
3163 {
3164         int     error;
3165 
3166         trace_xfs_log_force(mp, lsn);
3167         error = _xfs_log_force_lsn(mp, lsn, flags, NULL);
3168         if (error)
3169                 xfs_warn(mp, "%s: error %d returned.", __func__, error);
3170 }
3171 
3172 /*
3173  * Called when we want to mark the current iclog as being ready to sync to
3174  * disk.
3175  */
3176 STATIC void
3177 xlog_state_want_sync(
3178         struct xlog             *log,
3179         struct xlog_in_core     *iclog)
3180 {
3181         assert_spin_locked(&log->l_icloglock);
3182 
3183         if (iclog->ic_state == XLOG_STATE_ACTIVE) {
3184                 xlog_state_switch_iclogs(log, iclog, 0);
3185         } else {
3186                 ASSERT(iclog->ic_state &
3187                         (XLOG_STATE_WANT_SYNC|XLOG_STATE_IOERROR));
3188         }
3189 }
3190 
3191 
3192 /*****************************************************************************
3193  *
3194  *              TICKET functions
3195  *
3196  *****************************************************************************
3197  */
3198 
3199 /*
3200  * Free a used ticket when its refcount falls to zero.
3201  */
3202 void
3203 xfs_log_ticket_put(
3204         xlog_ticket_t   *ticket)
3205 {
3206         ASSERT(atomic_read(&ticket->t_ref) > 0);
3207         if (atomic_dec_and_test(&ticket->t_ref))
3208                 kmem_zone_free(xfs_log_ticket_zone, ticket);
3209 }
3210 
3211 xlog_ticket_t *
3212 xfs_log_ticket_get(
3213         xlog_ticket_t   *ticket)
3214 {
3215         ASSERT(atomic_read(&ticket->t_ref) > 0);
3216         atomic_inc(&ticket->t_ref);
3217         return ticket;
3218 }
3219 
3220 /*
3221  * Allocate and initialise a new log ticket.
3222  */
3223 struct xlog_ticket *
3224 xlog_ticket_alloc(
3225         struct xlog     *log,
3226         int             unit_bytes,
3227         int             cnt,
3228         char            client,
3229         bool            permanent,
3230         xfs_km_flags_t  alloc_flags)
3231 {
3232         struct xlog_ticket *tic;
3233         uint            num_headers;
3234         int             iclog_space;
3235 
3236         tic = kmem_zone_zalloc(xfs_log_ticket_zone, alloc_flags);
3237         if (!tic)
3238                 return NULL;
3239 
3240         /*
3241          * Permanent reservations have up to 'cnt'-1 active log operations
3242          * in the log.  A unit in this case is the amount of space for one
3243          * of these log operations.  Normal reservations have a cnt of 1
3244          * and their unit amount is the total amount of space required.
3245          *
3246          * The following lines of code account for non-transaction data
3247          * which occupy space in the on-disk log.
3248          *
3249          * Normal form of a transaction is:
3250          * <oph><trans-hdr><start-oph><reg1-oph><reg1><reg2-oph>...<commit-oph>
3251          * and then there are LR hdrs, split-recs and roundoff at end of syncs.
3252          *
3253          * We need to account for all the leadup data and trailer data
3254          * around the transaction data.
3255          * And then we need to account for the worst case in terms of using
3256          * more space.
3257          * The worst case will happen if:
3258          * - the placement of the transaction happens to be such that the
3259          *   roundoff is at its maximum
3260          * - the transaction data is synced before the commit record is synced
3261          *   i.e. <transaction-data><roundoff> | <commit-rec><roundoff>
3262          *   Therefore the commit record is in its own Log Record.
3263          *   This can happen as the commit record is called with its
3264          *   own region to xlog_write().
3265          *   This then means that in the worst case, roundoff can happen for
3266          *   the commit-rec as well.
3267          *   The commit-rec is smaller than padding in this scenario and so it is
3268          *   not added separately.
3269          */
3270 
3271         /* for trans header */
3272         unit_bytes += sizeof(xlog_op_header_t);
3273         unit_bytes += sizeof(xfs_trans_header_t);
3274 
3275         /* for start-rec */
3276         unit_bytes += sizeof(xlog_op_header_t);
3277 
3278         /*
3279          * for LR headers - the space for data in an iclog is the size minus
3280          * the space used for the headers. If we use the iclog size, then we
3281          * undercalculate the number of headers required.
3282          *
3283          * Furthermore - the addition of op headers for split-recs might
3284          * increase the space required enough to require more log and op
3285          * headers, so take that into account too.
3286          *
3287          * IMPORTANT: This reservation makes the assumption that if this
3288          * transaction is the first in an iclog and hence has the LR headers
3289          * accounted to it, then the remaining space in the iclog is
3290          * exclusively for this transaction.  i.e. if the transaction is larger
3291          * than the iclog, it will be the only thing in that iclog.
3292          * Fundamentally, this means we must pass the entire log vector to
3293          * xlog_write to guarantee this.
3294          */
3295         iclog_space = log->l_iclog_size - log->l_iclog_hsize;
3296         num_headers = howmany(unit_bytes, iclog_space);
3297 
3298         /* for split-recs - ophdrs added when data split over LRs */
3299         unit_bytes += sizeof(xlog_op_header_t) * num_headers;
3300 
3301         /* add extra header reservations if we overrun */
3302         while (!num_headers ||
3303                howmany(unit_bytes, iclog_space) > num_headers) {
3304                 unit_bytes += sizeof(xlog_op_header_t);
3305                 num_headers++;
3306         }
3307         unit_bytes += log->l_iclog_hsize * num_headers;
3308 
3309         /* for commit-rec LR header - note: padding will subsume the ophdr */
3310         unit_bytes += log->l_iclog_hsize;
3311 
3312         /* for roundoff padding for transaction data and one for commit record */
3313         if (xfs_sb_version_haslogv2(&log->l_mp->m_sb) &&
3314             log->l_mp->m_sb.sb_logsunit > 1) {
3315                 /* log su roundoff */
3316                 unit_bytes += 2*log->l_mp->m_sb.sb_logsunit;
3317         } else {
3318                 /* BB roundoff */
3319                 unit_bytes += 2*BBSIZE;
3320         }
3321 
3322         atomic_set(&tic->t_ref, 1);
3323         tic->t_task             = current;
3324         INIT_LIST_HEAD(&tic->t_queue);
3325         tic->t_unit_res         = unit_bytes;
3326         tic->t_curr_res         = unit_bytes;
3327         tic->t_cnt              = cnt;
3328         tic->t_ocnt             = cnt;
3329         tic->t_tid              = random32();
3330         tic->t_clientid         = client;
3331         tic->t_flags            = XLOG_TIC_INITED;
3332         tic->t_trans_type       = 0;
3333         if (permanent)
3334                 tic->t_flags |= XLOG_TIC_PERM_RESERV;
3335 
3336         xlog_tic_reset_res(tic);
3337 
3338         return tic;
3339 }
3340 
3341 
3342 /******************************************************************************
3343  *
3344  *              Log debug routines
3345  *
3346  ******************************************************************************
3347  */
3348 #if defined(DEBUG)
3349 /*
3350  * Make sure that the destination ptr is within the valid data region of
3351  * one of the iclogs.  This uses backup pointers stored in a different
3352  * part of the log in case we trash the log structure.
3353  */
3354 void
3355 xlog_verify_dest_ptr(
3356         struct xlog     *log,
3357         char            *ptr)
3358 {
3359         int i;
3360         int good_ptr = 0;
3361 
3362         for (i = 0; i < log->l_iclog_bufs; i++) {
3363                 if (ptr >= log->l_iclog_bak[i] &&
3364                     ptr <= log->l_iclog_bak[i] + log->l_iclog_size)
3365                         good_ptr++;
3366         }
3367 
3368         if (!good_ptr)
3369                 xfs_emerg(log->l_mp, "%s: invalid ptr", __func__);
3370 }
3371 
3372 /*
3373  * Check to make sure the grant write head didn't just over lap the tail.  If
3374  * the cycles are the same, we can't be overlapping.  Otherwise, make sure that
3375  * the cycles differ by exactly one and check the byte count.
3376  *
3377  * This check is run unlocked, so can give false positives. Rather than assert
3378  * on failures, use a warn-once flag and a panic tag to allow the admin to
3379  * determine if they want to panic the machine when such an error occurs. For
3380  * debug kernels this will have the same effect as using an assert but, unlinke
3381  * an assert, it can be turned off at runtime.
3382  */
3383 STATIC void
3384 xlog_verify_grant_tail(
3385         struct xlog     *log)
3386 {
3387         int             tail_cycle, tail_blocks;
3388         int             cycle, space;
3389 
3390         xlog_crack_grant_head(&log->l_write_head.grant, &cycle, &space);
3391         xlog_crack_atomic_lsn(&log->l_tail_lsn, &tail_cycle, &tail_blocks);
3392         if (tail_cycle != cycle) {
3393                 if (cycle - 1 != tail_cycle &&
3394                     !(log->l_flags & XLOG_TAIL_WARN)) {
3395                         xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,
3396                                 "%s: cycle - 1 != tail_cycle", __func__);
3397                         log->l_flags |= XLOG_TAIL_WARN;
3398                 }
3399 
3400                 if (space > BBTOB(tail_blocks) &&
3401                     !(log->l_flags & XLOG_TAIL_WARN)) {
3402                         xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,
3403                                 "%s: space > BBTOB(tail_blocks)", __func__);
3404                         log->l_flags |= XLOG_TAIL_WARN;
3405                 }
3406         }
3407 }
3408 
3409 /* check if it will fit */
3410 STATIC void
3411 xlog_verify_tail_lsn(
3412         struct xlog             *log,
3413         struct xlog_in_core     *iclog,
3414         xfs_lsn_t               tail_lsn)
3415 {
3416     int blocks;
3417 
3418     if (CYCLE_LSN(tail_lsn) == log->l_prev_cycle) {
3419         blocks =
3420             log->l_logBBsize - (log->l_prev_block - BLOCK_LSN(tail_lsn));
3421         if (blocks < BTOBB(iclog->ic_offset)+BTOBB(log->l_iclog_hsize))
3422                 xfs_emerg(log->l_mp, "%s: ran out of log space", __func__);
3423     } else {
3424         ASSERT(CYCLE_LSN(tail_lsn)+1 == log->l_prev_cycle);
3425 
3426         if (BLOCK_LSN(tail_lsn) == log->l_prev_block)
3427                 xfs_emerg(log->l_mp, "%s: tail wrapped", __func__);
3428 
3429         blocks = BLOCK_LSN(tail_lsn) - log->l_prev_block;
3430         if (blocks < BTOBB(iclog->ic_offset) + 1)
3431                 xfs_emerg(log->l_mp, "%s: ran out of log space", __func__);
3432     }
3433 }       /* xlog_verify_tail_lsn */
3434 
3435 /*
3436  * Perform a number of checks on the iclog before writing to disk.
3437  *
3438  * 1. Make sure the iclogs are still circular
3439  * 2. Make sure we have a good magic number
3440  * 3. Make sure we don't have magic numbers in the data
3441  * 4. Check fields of each log operation header for:
3442  *      A. Valid client identifier
3443  *      B. tid ptr value falls in valid ptr space (user space code)
3444  *      C. Length in log record header is correct according to the
3445  *              individual operation headers within record.
3446  * 5. When a bwrite will occur within 5 blocks of the front of the physical
3447  *      log, check the preceding blocks of the physical log to make sure all
3448  *      the cycle numbers agree with the current cycle number.
3449  */
3450 STATIC void
3451 xlog_verify_iclog(
3452         struct xlog             *log,
3453         struct xlog_in_core     *iclog,
3454         int                     count,
3455         boolean_t               syncing)
3456 {
3457         xlog_op_header_t        *ophead;
3458         xlog_in_core_t          *icptr;
3459         xlog_in_core_2_t        *xhdr;
3460         xfs_caddr_t             ptr;
3461         xfs_caddr_t             base_ptr;
3462         __psint_t               field_offset;
3463         __uint8_t               clientid;
3464         int                     len, i, j, k, op_len;
3465         int                     idx;
3466 
3467         /* check validity of iclog pointers */
3468         spin_lock(&log->l_icloglock);
3469         icptr = log->l_iclog;
3470         for (i=0; i < log->l_iclog_bufs; i++) {
3471                 if (icptr == NULL)
3472                         xfs_emerg(log->l_mp, "%s: invalid ptr", __func__);
3473                 icptr = icptr->ic_next;
3474         }
3475         if (icptr != log->l_iclog)
3476                 xfs_emerg(log->l_mp, "%s: corrupt iclog ring", __func__);
3477         spin_unlock(&log->l_icloglock);
3478 
3479         /* check log magic numbers */
3480         if (iclog->ic_header.h_magicno != cpu_to_be32(XLOG_HEADER_MAGIC_NUM))
3481                 xfs_emerg(log->l_mp, "%s: invalid magic num", __func__);
3482 
3483         ptr = (xfs_caddr_t) &iclog->ic_header;
3484         for (ptr += BBSIZE; ptr < ((xfs_caddr_t)&iclog->ic_header) + count;
3485              ptr += BBSIZE) {
3486                 if (*(__be32 *)ptr == cpu_to_be32(XLOG_HEADER_MAGIC_NUM))
3487                         xfs_emerg(log->l_mp, "%s: unexpected magic num",
3488                                 __func__);
3489         }
3490 
3491         /* check fields */
3492         len = be32_to_cpu(iclog->ic_header.h_num_logops);
3493         ptr = iclog->ic_datap;
3494         base_ptr = ptr;
3495         ophead = (xlog_op_header_t *)ptr;
3496         xhdr = iclog->ic_data;
3497         for (i = 0; i < len; i++) {
3498                 ophead = (xlog_op_header_t *)ptr;
3499 
3500                 /* clientid is only 1 byte */
3501                 field_offset = (__psint_t)
3502                                ((xfs_caddr_t)&(ophead->oh_clientid) - base_ptr);
3503                 if (syncing == B_FALSE || (field_offset & 0x1ff)) {
3504                         clientid = ophead->oh_clientid;
3505                 } else {
3506                         idx = BTOBBT((xfs_caddr_t)&(ophead->oh_clientid) - iclog->ic_datap);
3507                         if (idx >= (XLOG_HEADER_CYCLE_SIZE / BBSIZE)) {
3508                                 j = idx / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
3509                                 k = idx % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
3510                                 clientid = xlog_get_client_id(
3511                                         xhdr[j].hic_xheader.xh_cycle_data[k]);
3512                         } else {
3513                                 clientid = xlog_get_client_id(
3514                                         iclog->ic_header.h_cycle_data[idx]);
3515                         }
3516                 }
3517                 if (clientid != XFS_TRANSACTION && clientid != XFS_LOG)
3518                         xfs_warn(log->l_mp,
3519                                 "%s: invalid clientid %d op 0x%p offset 0x%lx",
3520                                 __func__, clientid, ophead,
3521                                 (unsigned long)field_offset);
3522 
3523                 /* check length */
3524                 field_offset = (__psint_t)
3525                                ((xfs_caddr_t)&(ophead->oh_len) - base_ptr);
3526                 if (syncing == B_FALSE || (field_offset & 0x1ff)) {
3527                         op_len = be32_to_cpu(ophead->oh_len);
3528                 } else {
3529                         idx = BTOBBT((__psint_t)&ophead->oh_len -
3530                                     (__psint_t)iclog->ic_datap);
3531                         if (idx >= (XLOG_HEADER_CYCLE_SIZE / BBSIZE)) {
3532                                 j = idx / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
3533                                 k = idx % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
3534                                 op_len = be32_to_cpu(xhdr[j].hic_xheader.xh_cycle_data[k]);
3535                         } else {
3536                                 op_len = be32_to_cpu(iclog->ic_header.h_cycle_data[idx]);
3537                         }
3538                 }
3539                 ptr += sizeof(xlog_op_header_t) + op_len;
3540         }
3541 }       /* xlog_verify_iclog */
3542 #endif
3543 
3544 /*
3545  * Mark all iclogs IOERROR. l_icloglock is held by the caller.
3546  */
3547 STATIC int
3548 xlog_state_ioerror(
3549         struct xlog     *log)
3550 {
3551         xlog_in_core_t  *iclog, *ic;
3552 
3553         iclog = log->l_iclog;
3554         if (! (iclog->ic_state & XLOG_STATE_IOERROR)) {
3555                 /*
3556                  * Mark all the incore logs IOERROR.
3557                  * From now on, no log flushes will result.
3558                  */
3559                 ic = iclog;
3560                 do {
3561                         ic->ic_state = XLOG_STATE_IOERROR;
3562                         ic = ic->ic_next;
3563                 } while (ic != iclog);
3564                 return 0;
3565         }
3566         /*
3567          * Return non-zero, if state transition has already happened.
3568          */
3569         return 1;
3570 }
3571 
3572 /*
3573  * This is called from xfs_force_shutdown, when we're forcibly
3574  * shutting down the filesystem, typically because of an IO error.
3575  * Our main objectives here are to make sure that:
3576  *      a. the filesystem gets marked 'SHUTDOWN' for all interested
3577  *         parties to find out, 'atomically'.
3578  *      b. those who're sleeping on log reservations, pinned objects and
3579  *          other resources get woken up, and be told the bad news.
3580  *      c. nothing new gets queued up after (a) and (b) are done.
3581  *      d. if !logerror, flush the iclogs to disk, then seal them off
3582  *         for business.
3583  *
3584  * Note: for delayed logging the !logerror case needs to flush the regions
3585  * held in memory out to the iclogs before flushing them to disk. This needs
3586  * to be done before the log is marked as shutdown, otherwise the flush to the
3587  * iclogs will fail.
3588  */
3589 int
3590 xfs_log_force_umount(
3591         struct xfs_mount        *mp,
3592         int                     logerror)
3593 {
3594         struct xlog     *log;
3595         int             retval;
3596 
3597         log = mp->m_log;
3598 
3599         /*
3600          * If this happens during log recovery, don't worry about
3601          * locking; the log isn't open for business yet.
3602          */
3603         if (!log ||
3604             log->l_flags & XLOG_ACTIVE_RECOVERY) {
3605                 mp->m_flags |= XFS_MOUNT_FS_SHUTDOWN;
3606                 if (mp->m_sb_bp)
3607                         XFS_BUF_DONE(mp->m_sb_bp);
3608                 return 0;
3609         }
3610 
3611         /*
3612          * Somebody could've already done the hard work for us.
3613          * No need to get locks for this.
3614          */
3615         if (logerror && log->l_iclog->ic_state & XLOG_STATE_IOERROR) {
3616                 ASSERT(XLOG_FORCED_SHUTDOWN(log));
3617                 return 1;
3618         }
3619         retval = 0;
3620 
3621         /*
3622          * Flush the in memory commit item list before marking the log as
3623          * being shut down. We need to do it in this order to ensure all the
3624          * completed transactions are flushed to disk with the xfs_log_force()
3625          * call below.
3626          */
3627         if (!logerror)
3628                 xlog_cil_force(log);
3629 
3630         /*
3631          * mark the filesystem and the as in a shutdown state and wake
3632          * everybody up to tell them the bad news.
3633          */
3634         spin_lock(&log->l_icloglock);
3635         mp->m_flags |= XFS_MOUNT_FS_SHUTDOWN;
3636         if (mp->m_sb_bp)
3637                 XFS_BUF_DONE(mp->m_sb_bp);
3638 
3639         /*
3640          * This flag is sort of redundant because of the mount flag, but
3641          * it's good to maintain the separation between the log and the rest
3642          * of XFS.
3643          */
3644         log->l_flags |= XLOG_IO_ERROR;
3645 
3646         /*
3647          * If we hit a log error, we want to mark all the iclogs IOERROR
3648          * while we're still holding the loglock.
3649          */
3650         if (logerror)
3651                 retval = xlog_state_ioerror(log);
3652         spin_unlock(&log->l_icloglock);
3653 
3654         /*
3655          * We don't want anybody waiting for log reservations after this. That
3656          * means we have to wake up everybody queued up on reserveq as well as
3657          * writeq.  In addition, we make sure in xlog_{re}grant_log_space that
3658          * we don't enqueue anything once the SHUTDOWN flag is set, and this
3659          * action is protected by the grant locks.
3660          */
3661         xlog_grant_head_wake_all(&log->l_reserve_head);
3662         xlog_grant_head_wake_all(&log->l_write_head);
3663 
3664         if (!(log->l_iclog->ic_state & XLOG_STATE_IOERROR)) {
3665                 ASSERT(!logerror);
3666                 /*
3667                  * Force the incore logs to disk before shutting the
3668                  * log down completely.
3669                  */
3670                 _xfs_log_force(mp, XFS_LOG_SYNC, NULL);
3671 
3672                 spin_lock(&log->l_icloglock);
3673                 retval = xlog_state_ioerror(log);
3674                 spin_unlock(&log->l_icloglock);
3675         }
3676         /*
3677          * Wake up everybody waiting on xfs_log_force.
3678          * Callback all log item committed functions as if the
3679          * log writes were completed.
3680          */
3681         xlog_state_do_callback(log, XFS_LI_ABORTED, NULL);
3682 
3683 #ifdef XFSERRORDEBUG
3684         {
3685                 xlog_in_core_t  *iclog;
3686 
3687                 spin_lock(&log->l_icloglock);
3688                 iclog = log->l_iclog;
3689                 do {
3690                         ASSERT(iclog->ic_callback == 0);
3691                         iclog = iclog->ic_next;
3692                 } while (iclog != log->l_iclog);
3693                 spin_unlock(&log->l_icloglock);
3694         }
3695 #endif
3696         /* return non-zero if log IOERROR transition had already happened */
3697         return retval;
3698 }
3699 
3700 STATIC int
3701 xlog_iclogs_empty(
3702         struct xlog     *log)
3703 {
3704         xlog_in_core_t  *iclog;
3705 
3706         iclog = log->l_iclog;
3707         do {
3708                 /* endianness does not matter here, zero is zero in
3709                  * any language.
3710                  */
3711                 if (iclog->ic_header.h_num_logops)
3712                         return 0;
3713                 iclog = iclog->ic_next;
3714         } while (iclog != log->l_iclog);
3715         return 1;
3716 }
3717 

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