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TOMOYO Linux Cross Reference
Linux/fs/nilfs2/segment.c

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  1 /*
  2  * segment.c - NILFS segment constructor.
  3  *
  4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  *
 16  * Written by Ryusuke Konishi.
 17  *
 18  */
 19 
 20 #include <linux/pagemap.h>
 21 #include <linux/buffer_head.h>
 22 #include <linux/writeback.h>
 23 #include <linux/bitops.h>
 24 #include <linux/bio.h>
 25 #include <linux/completion.h>
 26 #include <linux/blkdev.h>
 27 #include <linux/backing-dev.h>
 28 #include <linux/freezer.h>
 29 #include <linux/kthread.h>
 30 #include <linux/crc32.h>
 31 #include <linux/pagevec.h>
 32 #include <linux/slab.h>
 33 #include <linux/sched/signal.h>
 34 
 35 #include "nilfs.h"
 36 #include "btnode.h"
 37 #include "page.h"
 38 #include "segment.h"
 39 #include "sufile.h"
 40 #include "cpfile.h"
 41 #include "ifile.h"
 42 #include "segbuf.h"
 43 
 44 
 45 /*
 46  * Segment constructor
 47  */
 48 #define SC_N_INODEVEC   16   /* Size of locally allocated inode vector */
 49 
 50 #define SC_MAX_SEGDELTA 64   /*
 51                               * Upper limit of the number of segments
 52                               * appended in collection retry loop
 53                               */
 54 
 55 /* Construction mode */
 56 enum {
 57         SC_LSEG_SR = 1, /* Make a logical segment having a super root */
 58         SC_LSEG_DSYNC,  /*
 59                          * Flush data blocks of a given file and make
 60                          * a logical segment without a super root.
 61                          */
 62         SC_FLUSH_FILE,  /*
 63                          * Flush data files, leads to segment writes without
 64                          * creating a checkpoint.
 65                          */
 66         SC_FLUSH_DAT,   /*
 67                          * Flush DAT file.  This also creates segments
 68                          * without a checkpoint.
 69                          */
 70 };
 71 
 72 /* Stage numbers of dirty block collection */
 73 enum {
 74         NILFS_ST_INIT = 0,
 75         NILFS_ST_GC,            /* Collecting dirty blocks for GC */
 76         NILFS_ST_FILE,
 77         NILFS_ST_IFILE,
 78         NILFS_ST_CPFILE,
 79         NILFS_ST_SUFILE,
 80         NILFS_ST_DAT,
 81         NILFS_ST_SR,            /* Super root */
 82         NILFS_ST_DSYNC,         /* Data sync blocks */
 83         NILFS_ST_DONE,
 84 };
 85 
 86 #define CREATE_TRACE_POINTS
 87 #include <trace/events/nilfs2.h>
 88 
 89 /*
 90  * nilfs_sc_cstage_inc(), nilfs_sc_cstage_set(), nilfs_sc_cstage_get() are
 91  * wrapper functions of stage count (nilfs_sc_info->sc_stage.scnt). Users of
 92  * the variable must use them because transition of stage count must involve
 93  * trace events (trace_nilfs2_collection_stage_transition).
 94  *
 95  * nilfs_sc_cstage_get() isn't required for the above purpose because it doesn't
 96  * produce tracepoint events. It is provided just for making the intention
 97  * clear.
 98  */
 99 static inline void nilfs_sc_cstage_inc(struct nilfs_sc_info *sci)
100 {
101         sci->sc_stage.scnt++;
102         trace_nilfs2_collection_stage_transition(sci);
103 }
104 
105 static inline void nilfs_sc_cstage_set(struct nilfs_sc_info *sci, int next_scnt)
106 {
107         sci->sc_stage.scnt = next_scnt;
108         trace_nilfs2_collection_stage_transition(sci);
109 }
110 
111 static inline int nilfs_sc_cstage_get(struct nilfs_sc_info *sci)
112 {
113         return sci->sc_stage.scnt;
114 }
115 
116 /* State flags of collection */
117 #define NILFS_CF_NODE           0x0001  /* Collecting node blocks */
118 #define NILFS_CF_IFILE_STARTED  0x0002  /* IFILE stage has started */
119 #define NILFS_CF_SUFREED        0x0004  /* segment usages has been freed */
120 #define NILFS_CF_HISTORY_MASK   (NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
121 
122 /* Operations depending on the construction mode and file type */
123 struct nilfs_sc_operations {
124         int (*collect_data)(struct nilfs_sc_info *, struct buffer_head *,
125                             struct inode *);
126         int (*collect_node)(struct nilfs_sc_info *, struct buffer_head *,
127                             struct inode *);
128         int (*collect_bmap)(struct nilfs_sc_info *, struct buffer_head *,
129                             struct inode *);
130         void (*write_data_binfo)(struct nilfs_sc_info *,
131                                  struct nilfs_segsum_pointer *,
132                                  union nilfs_binfo *);
133         void (*write_node_binfo)(struct nilfs_sc_info *,
134                                  struct nilfs_segsum_pointer *,
135                                  union nilfs_binfo *);
136 };
137 
138 /*
139  * Other definitions
140  */
141 static void nilfs_segctor_start_timer(struct nilfs_sc_info *);
142 static void nilfs_segctor_do_flush(struct nilfs_sc_info *, int);
143 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *);
144 static void nilfs_dispose_list(struct the_nilfs *, struct list_head *, int);
145 
146 #define nilfs_cnt32_gt(a, b)   \
147         (typecheck(__u32, a) && typecheck(__u32, b) && \
148          ((__s32)(b) - (__s32)(a) < 0))
149 #define nilfs_cnt32_ge(a, b)   \
150         (typecheck(__u32, a) && typecheck(__u32, b) && \
151          ((__s32)(a) - (__s32)(b) >= 0))
152 #define nilfs_cnt32_lt(a, b)  nilfs_cnt32_gt(b, a)
153 #define nilfs_cnt32_le(a, b)  nilfs_cnt32_ge(b, a)
154 
155 static int nilfs_prepare_segment_lock(struct super_block *sb,
156                                       struct nilfs_transaction_info *ti)
157 {
158         struct nilfs_transaction_info *cur_ti = current->journal_info;
159         void *save = NULL;
160 
161         if (cur_ti) {
162                 if (cur_ti->ti_magic == NILFS_TI_MAGIC)
163                         return ++cur_ti->ti_count;
164 
165                 /*
166                  * If journal_info field is occupied by other FS,
167                  * it is saved and will be restored on
168                  * nilfs_transaction_commit().
169                  */
170                 nilfs_msg(sb, KERN_WARNING, "journal info from a different FS");
171                 save = current->journal_info;
172         }
173         if (!ti) {
174                 ti = kmem_cache_alloc(nilfs_transaction_cachep, GFP_NOFS);
175                 if (!ti)
176                         return -ENOMEM;
177                 ti->ti_flags = NILFS_TI_DYNAMIC_ALLOC;
178         } else {
179                 ti->ti_flags = 0;
180         }
181         ti->ti_count = 0;
182         ti->ti_save = save;
183         ti->ti_magic = NILFS_TI_MAGIC;
184         current->journal_info = ti;
185         return 0;
186 }
187 
188 /**
189  * nilfs_transaction_begin - start indivisible file operations.
190  * @sb: super block
191  * @ti: nilfs_transaction_info
192  * @vacancy_check: flags for vacancy rate checks
193  *
194  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
195  * the segment semaphore, to make a segment construction and write tasks
196  * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
197  * The region enclosed by these two functions can be nested.  To avoid a
198  * deadlock, the semaphore is only acquired or released in the outermost call.
199  *
200  * This function allocates a nilfs_transaction_info struct to keep context
201  * information on it.  It is initialized and hooked onto the current task in
202  * the outermost call.  If a pre-allocated struct is given to @ti, it is used
203  * instead; otherwise a new struct is assigned from a slab.
204  *
205  * When @vacancy_check flag is set, this function will check the amount of
206  * free space, and will wait for the GC to reclaim disk space if low capacity.
207  *
208  * Return Value: On success, 0 is returned. On error, one of the following
209  * negative error code is returned.
210  *
211  * %-ENOMEM - Insufficient memory available.
212  *
213  * %-ENOSPC - No space left on device
214  */
215 int nilfs_transaction_begin(struct super_block *sb,
216                             struct nilfs_transaction_info *ti,
217                             int vacancy_check)
218 {
219         struct the_nilfs *nilfs;
220         int ret = nilfs_prepare_segment_lock(sb, ti);
221         struct nilfs_transaction_info *trace_ti;
222 
223         if (unlikely(ret < 0))
224                 return ret;
225         if (ret > 0) {
226                 trace_ti = current->journal_info;
227 
228                 trace_nilfs2_transaction_transition(sb, trace_ti,
229                                     trace_ti->ti_count, trace_ti->ti_flags,
230                                     TRACE_NILFS2_TRANSACTION_BEGIN);
231                 return 0;
232         }
233 
234         sb_start_intwrite(sb);
235 
236         nilfs = sb->s_fs_info;
237         down_read(&nilfs->ns_segctor_sem);
238         if (vacancy_check && nilfs_near_disk_full(nilfs)) {
239                 up_read(&nilfs->ns_segctor_sem);
240                 ret = -ENOSPC;
241                 goto failed;
242         }
243 
244         trace_ti = current->journal_info;
245         trace_nilfs2_transaction_transition(sb, trace_ti, trace_ti->ti_count,
246                                             trace_ti->ti_flags,
247                                             TRACE_NILFS2_TRANSACTION_BEGIN);
248         return 0;
249 
250  failed:
251         ti = current->journal_info;
252         current->journal_info = ti->ti_save;
253         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
254                 kmem_cache_free(nilfs_transaction_cachep, ti);
255         sb_end_intwrite(sb);
256         return ret;
257 }
258 
259 /**
260  * nilfs_transaction_commit - commit indivisible file operations.
261  * @sb: super block
262  *
263  * nilfs_transaction_commit() releases the read semaphore which is
264  * acquired by nilfs_transaction_begin(). This is only performed
265  * in outermost call of this function.  If a commit flag is set,
266  * nilfs_transaction_commit() sets a timer to start the segment
267  * constructor.  If a sync flag is set, it starts construction
268  * directly.
269  */
270 int nilfs_transaction_commit(struct super_block *sb)
271 {
272         struct nilfs_transaction_info *ti = current->journal_info;
273         struct the_nilfs *nilfs = sb->s_fs_info;
274         int err = 0;
275 
276         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
277         ti->ti_flags |= NILFS_TI_COMMIT;
278         if (ti->ti_count > 0) {
279                 ti->ti_count--;
280                 trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
281                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
282                 return 0;
283         }
284         if (nilfs->ns_writer) {
285                 struct nilfs_sc_info *sci = nilfs->ns_writer;
286 
287                 if (ti->ti_flags & NILFS_TI_COMMIT)
288                         nilfs_segctor_start_timer(sci);
289                 if (atomic_read(&nilfs->ns_ndirtyblks) > sci->sc_watermark)
290                         nilfs_segctor_do_flush(sci, 0);
291         }
292         up_read(&nilfs->ns_segctor_sem);
293         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
294                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_COMMIT);
295 
296         current->journal_info = ti->ti_save;
297 
298         if (ti->ti_flags & NILFS_TI_SYNC)
299                 err = nilfs_construct_segment(sb);
300         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
301                 kmem_cache_free(nilfs_transaction_cachep, ti);
302         sb_end_intwrite(sb);
303         return err;
304 }
305 
306 void nilfs_transaction_abort(struct super_block *sb)
307 {
308         struct nilfs_transaction_info *ti = current->journal_info;
309         struct the_nilfs *nilfs = sb->s_fs_info;
310 
311         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
312         if (ti->ti_count > 0) {
313                 ti->ti_count--;
314                 trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
315                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
316                 return;
317         }
318         up_read(&nilfs->ns_segctor_sem);
319 
320         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
321                     ti->ti_flags, TRACE_NILFS2_TRANSACTION_ABORT);
322 
323         current->journal_info = ti->ti_save;
324         if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
325                 kmem_cache_free(nilfs_transaction_cachep, ti);
326         sb_end_intwrite(sb);
327 }
328 
329 void nilfs_relax_pressure_in_lock(struct super_block *sb)
330 {
331         struct the_nilfs *nilfs = sb->s_fs_info;
332         struct nilfs_sc_info *sci = nilfs->ns_writer;
333 
334         if (!sci || !sci->sc_flush_request)
335                 return;
336 
337         set_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
338         up_read(&nilfs->ns_segctor_sem);
339 
340         down_write(&nilfs->ns_segctor_sem);
341         if (sci->sc_flush_request &&
342             test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags)) {
343                 struct nilfs_transaction_info *ti = current->journal_info;
344 
345                 ti->ti_flags |= NILFS_TI_WRITER;
346                 nilfs_segctor_do_immediate_flush(sci);
347                 ti->ti_flags &= ~NILFS_TI_WRITER;
348         }
349         downgrade_write(&nilfs->ns_segctor_sem);
350 }
351 
352 static void nilfs_transaction_lock(struct super_block *sb,
353                                    struct nilfs_transaction_info *ti,
354                                    int gcflag)
355 {
356         struct nilfs_transaction_info *cur_ti = current->journal_info;
357         struct the_nilfs *nilfs = sb->s_fs_info;
358         struct nilfs_sc_info *sci = nilfs->ns_writer;
359 
360         WARN_ON(cur_ti);
361         ti->ti_flags = NILFS_TI_WRITER;
362         ti->ti_count = 0;
363         ti->ti_save = cur_ti;
364         ti->ti_magic = NILFS_TI_MAGIC;
365         current->journal_info = ti;
366 
367         for (;;) {
368                 trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
369                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_TRYLOCK);
370 
371                 down_write(&nilfs->ns_segctor_sem);
372                 if (!test_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags))
373                         break;
374 
375                 nilfs_segctor_do_immediate_flush(sci);
376 
377                 up_write(&nilfs->ns_segctor_sem);
378                 cond_resched();
379         }
380         if (gcflag)
381                 ti->ti_flags |= NILFS_TI_GC;
382 
383         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
384                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_LOCK);
385 }
386 
387 static void nilfs_transaction_unlock(struct super_block *sb)
388 {
389         struct nilfs_transaction_info *ti = current->journal_info;
390         struct the_nilfs *nilfs = sb->s_fs_info;
391 
392         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
393         BUG_ON(ti->ti_count > 0);
394 
395         up_write(&nilfs->ns_segctor_sem);
396         current->journal_info = ti->ti_save;
397 
398         trace_nilfs2_transaction_transition(sb, ti, ti->ti_count,
399                             ti->ti_flags, TRACE_NILFS2_TRANSACTION_UNLOCK);
400 }
401 
402 static void *nilfs_segctor_map_segsum_entry(struct nilfs_sc_info *sci,
403                                             struct nilfs_segsum_pointer *ssp,
404                                             unsigned int bytes)
405 {
406         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
407         unsigned int blocksize = sci->sc_super->s_blocksize;
408         void *p;
409 
410         if (unlikely(ssp->offset + bytes > blocksize)) {
411                 ssp->offset = 0;
412                 BUG_ON(NILFS_SEGBUF_BH_IS_LAST(ssp->bh,
413                                                &segbuf->sb_segsum_buffers));
414                 ssp->bh = NILFS_SEGBUF_NEXT_BH(ssp->bh);
415         }
416         p = ssp->bh->b_data + ssp->offset;
417         ssp->offset += bytes;
418         return p;
419 }
420 
421 /**
422  * nilfs_segctor_reset_segment_buffer - reset the current segment buffer
423  * @sci: nilfs_sc_info
424  */
425 static int nilfs_segctor_reset_segment_buffer(struct nilfs_sc_info *sci)
426 {
427         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
428         struct buffer_head *sumbh;
429         unsigned int sumbytes;
430         unsigned int flags = 0;
431         int err;
432 
433         if (nilfs_doing_gc())
434                 flags = NILFS_SS_GC;
435         err = nilfs_segbuf_reset(segbuf, flags, sci->sc_seg_ctime, sci->sc_cno);
436         if (unlikely(err))
437                 return err;
438 
439         sumbh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
440         sumbytes = segbuf->sb_sum.sumbytes;
441         sci->sc_finfo_ptr.bh = sumbh;  sci->sc_finfo_ptr.offset = sumbytes;
442         sci->sc_binfo_ptr.bh = sumbh;  sci->sc_binfo_ptr.offset = sumbytes;
443         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
444         return 0;
445 }
446 
447 static int nilfs_segctor_feed_segment(struct nilfs_sc_info *sci)
448 {
449         sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
450         if (NILFS_SEGBUF_IS_LAST(sci->sc_curseg, &sci->sc_segbufs))
451                 return -E2BIG; /*
452                                 * The current segment is filled up
453                                 * (internal code)
454                                 */
455         sci->sc_curseg = NILFS_NEXT_SEGBUF(sci->sc_curseg);
456         return nilfs_segctor_reset_segment_buffer(sci);
457 }
458 
459 static int nilfs_segctor_add_super_root(struct nilfs_sc_info *sci)
460 {
461         struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
462         int err;
463 
464         if (segbuf->sb_sum.nblocks >= segbuf->sb_rest_blocks) {
465                 err = nilfs_segctor_feed_segment(sci);
466                 if (err)
467                         return err;
468                 segbuf = sci->sc_curseg;
469         }
470         err = nilfs_segbuf_extend_payload(segbuf, &segbuf->sb_super_root);
471         if (likely(!err))
472                 segbuf->sb_sum.flags |= NILFS_SS_SR;
473         return err;
474 }
475 
476 /*
477  * Functions for making segment summary and payloads
478  */
479 static int nilfs_segctor_segsum_block_required(
480         struct nilfs_sc_info *sci, const struct nilfs_segsum_pointer *ssp,
481         unsigned int binfo_size)
482 {
483         unsigned int blocksize = sci->sc_super->s_blocksize;
484         /* Size of finfo and binfo is enough small against blocksize */
485 
486         return ssp->offset + binfo_size +
487                 (!sci->sc_blk_cnt ? sizeof(struct nilfs_finfo) : 0) >
488                 blocksize;
489 }
490 
491 static void nilfs_segctor_begin_finfo(struct nilfs_sc_info *sci,
492                                       struct inode *inode)
493 {
494         sci->sc_curseg->sb_sum.nfinfo++;
495         sci->sc_binfo_ptr = sci->sc_finfo_ptr;
496         nilfs_segctor_map_segsum_entry(
497                 sci, &sci->sc_binfo_ptr, sizeof(struct nilfs_finfo));
498 
499         if (NILFS_I(inode)->i_root &&
500             !test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
501                 set_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
502         /* skip finfo */
503 }
504 
505 static void nilfs_segctor_end_finfo(struct nilfs_sc_info *sci,
506                                     struct inode *inode)
507 {
508         struct nilfs_finfo *finfo;
509         struct nilfs_inode_info *ii;
510         struct nilfs_segment_buffer *segbuf;
511         __u64 cno;
512 
513         if (sci->sc_blk_cnt == 0)
514                 return;
515 
516         ii = NILFS_I(inode);
517 
518         if (test_bit(NILFS_I_GCINODE, &ii->i_state))
519                 cno = ii->i_cno;
520         else if (NILFS_ROOT_METADATA_FILE(inode->i_ino))
521                 cno = 0;
522         else
523                 cno = sci->sc_cno;
524 
525         finfo = nilfs_segctor_map_segsum_entry(sci, &sci->sc_finfo_ptr,
526                                                  sizeof(*finfo));
527         finfo->fi_ino = cpu_to_le64(inode->i_ino);
528         finfo->fi_nblocks = cpu_to_le32(sci->sc_blk_cnt);
529         finfo->fi_ndatablk = cpu_to_le32(sci->sc_datablk_cnt);
530         finfo->fi_cno = cpu_to_le64(cno);
531 
532         segbuf = sci->sc_curseg;
533         segbuf->sb_sum.sumbytes = sci->sc_binfo_ptr.offset +
534                 sci->sc_super->s_blocksize * (segbuf->sb_sum.nsumblk - 1);
535         sci->sc_finfo_ptr = sci->sc_binfo_ptr;
536         sci->sc_blk_cnt = sci->sc_datablk_cnt = 0;
537 }
538 
539 static int nilfs_segctor_add_file_block(struct nilfs_sc_info *sci,
540                                         struct buffer_head *bh,
541                                         struct inode *inode,
542                                         unsigned int binfo_size)
543 {
544         struct nilfs_segment_buffer *segbuf;
545         int required, err = 0;
546 
547  retry:
548         segbuf = sci->sc_curseg;
549         required = nilfs_segctor_segsum_block_required(
550                 sci, &sci->sc_binfo_ptr, binfo_size);
551         if (segbuf->sb_sum.nblocks + required + 1 > segbuf->sb_rest_blocks) {
552                 nilfs_segctor_end_finfo(sci, inode);
553                 err = nilfs_segctor_feed_segment(sci);
554                 if (err)
555                         return err;
556                 goto retry;
557         }
558         if (unlikely(required)) {
559                 err = nilfs_segbuf_extend_segsum(segbuf);
560                 if (unlikely(err))
561                         goto failed;
562         }
563         if (sci->sc_blk_cnt == 0)
564                 nilfs_segctor_begin_finfo(sci, inode);
565 
566         nilfs_segctor_map_segsum_entry(sci, &sci->sc_binfo_ptr, binfo_size);
567         /* Substitution to vblocknr is delayed until update_blocknr() */
568         nilfs_segbuf_add_file_buffer(segbuf, bh);
569         sci->sc_blk_cnt++;
570  failed:
571         return err;
572 }
573 
574 /*
575  * Callback functions that enumerate, mark, and collect dirty blocks
576  */
577 static int nilfs_collect_file_data(struct nilfs_sc_info *sci,
578                                    struct buffer_head *bh, struct inode *inode)
579 {
580         int err;
581 
582         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
583         if (err < 0)
584                 return err;
585 
586         err = nilfs_segctor_add_file_block(sci, bh, inode,
587                                            sizeof(struct nilfs_binfo_v));
588         if (!err)
589                 sci->sc_datablk_cnt++;
590         return err;
591 }
592 
593 static int nilfs_collect_file_node(struct nilfs_sc_info *sci,
594                                    struct buffer_head *bh,
595                                    struct inode *inode)
596 {
597         return nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
598 }
599 
600 static int nilfs_collect_file_bmap(struct nilfs_sc_info *sci,
601                                    struct buffer_head *bh,
602                                    struct inode *inode)
603 {
604         WARN_ON(!buffer_dirty(bh));
605         return nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
606 }
607 
608 static void nilfs_write_file_data_binfo(struct nilfs_sc_info *sci,
609                                         struct nilfs_segsum_pointer *ssp,
610                                         union nilfs_binfo *binfo)
611 {
612         struct nilfs_binfo_v *binfo_v = nilfs_segctor_map_segsum_entry(
613                 sci, ssp, sizeof(*binfo_v));
614         *binfo_v = binfo->bi_v;
615 }
616 
617 static void nilfs_write_file_node_binfo(struct nilfs_sc_info *sci,
618                                         struct nilfs_segsum_pointer *ssp,
619                                         union nilfs_binfo *binfo)
620 {
621         __le64 *vblocknr = nilfs_segctor_map_segsum_entry(
622                 sci, ssp, sizeof(*vblocknr));
623         *vblocknr = binfo->bi_v.bi_vblocknr;
624 }
625 
626 static const struct nilfs_sc_operations nilfs_sc_file_ops = {
627         .collect_data = nilfs_collect_file_data,
628         .collect_node = nilfs_collect_file_node,
629         .collect_bmap = nilfs_collect_file_bmap,
630         .write_data_binfo = nilfs_write_file_data_binfo,
631         .write_node_binfo = nilfs_write_file_node_binfo,
632 };
633 
634 static int nilfs_collect_dat_data(struct nilfs_sc_info *sci,
635                                   struct buffer_head *bh, struct inode *inode)
636 {
637         int err;
638 
639         err = nilfs_bmap_propagate(NILFS_I(inode)->i_bmap, bh);
640         if (err < 0)
641                 return err;
642 
643         err = nilfs_segctor_add_file_block(sci, bh, inode, sizeof(__le64));
644         if (!err)
645                 sci->sc_datablk_cnt++;
646         return err;
647 }
648 
649 static int nilfs_collect_dat_bmap(struct nilfs_sc_info *sci,
650                                   struct buffer_head *bh, struct inode *inode)
651 {
652         WARN_ON(!buffer_dirty(bh));
653         return nilfs_segctor_add_file_block(sci, bh, inode,
654                                             sizeof(struct nilfs_binfo_dat));
655 }
656 
657 static void nilfs_write_dat_data_binfo(struct nilfs_sc_info *sci,
658                                        struct nilfs_segsum_pointer *ssp,
659                                        union nilfs_binfo *binfo)
660 {
661         __le64 *blkoff = nilfs_segctor_map_segsum_entry(sci, ssp,
662                                                           sizeof(*blkoff));
663         *blkoff = binfo->bi_dat.bi_blkoff;
664 }
665 
666 static void nilfs_write_dat_node_binfo(struct nilfs_sc_info *sci,
667                                        struct nilfs_segsum_pointer *ssp,
668                                        union nilfs_binfo *binfo)
669 {
670         struct nilfs_binfo_dat *binfo_dat =
671                 nilfs_segctor_map_segsum_entry(sci, ssp, sizeof(*binfo_dat));
672         *binfo_dat = binfo->bi_dat;
673 }
674 
675 static const struct nilfs_sc_operations nilfs_sc_dat_ops = {
676         .collect_data = nilfs_collect_dat_data,
677         .collect_node = nilfs_collect_file_node,
678         .collect_bmap = nilfs_collect_dat_bmap,
679         .write_data_binfo = nilfs_write_dat_data_binfo,
680         .write_node_binfo = nilfs_write_dat_node_binfo,
681 };
682 
683 static const struct nilfs_sc_operations nilfs_sc_dsync_ops = {
684         .collect_data = nilfs_collect_file_data,
685         .collect_node = NULL,
686         .collect_bmap = NULL,
687         .write_data_binfo = nilfs_write_file_data_binfo,
688         .write_node_binfo = NULL,
689 };
690 
691 static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
692                                               struct list_head *listp,
693                                               size_t nlimit,
694                                               loff_t start, loff_t end)
695 {
696         struct address_space *mapping = inode->i_mapping;
697         struct pagevec pvec;
698         pgoff_t index = 0, last = ULONG_MAX;
699         size_t ndirties = 0;
700         int i;
701 
702         if (unlikely(start != 0 || end != LLONG_MAX)) {
703                 /*
704                  * A valid range is given for sync-ing data pages. The
705                  * range is rounded to per-page; extra dirty buffers
706                  * may be included if blocksize < pagesize.
707                  */
708                 index = start >> PAGE_SHIFT;
709                 last = end >> PAGE_SHIFT;
710         }
711         pagevec_init(&pvec);
712  repeat:
713         if (unlikely(index > last) ||
714             !pagevec_lookup_range_tag(&pvec, mapping, &index, last,
715                                 PAGECACHE_TAG_DIRTY))
716                 return ndirties;
717 
718         for (i = 0; i < pagevec_count(&pvec); i++) {
719                 struct buffer_head *bh, *head;
720                 struct page *page = pvec.pages[i];
721 
722                 lock_page(page);
723                 if (!page_has_buffers(page))
724                         create_empty_buffers(page, i_blocksize(inode), 0);
725                 unlock_page(page);
726 
727                 bh = head = page_buffers(page);
728                 do {
729                         if (!buffer_dirty(bh) || buffer_async_write(bh))
730                                 continue;
731                         get_bh(bh);
732                         list_add_tail(&bh->b_assoc_buffers, listp);
733                         ndirties++;
734                         if (unlikely(ndirties >= nlimit)) {
735                                 pagevec_release(&pvec);
736                                 cond_resched();
737                                 return ndirties;
738                         }
739                 } while (bh = bh->b_this_page, bh != head);
740         }
741         pagevec_release(&pvec);
742         cond_resched();
743         goto repeat;
744 }
745 
746 static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
747                                             struct list_head *listp)
748 {
749         struct nilfs_inode_info *ii = NILFS_I(inode);
750         struct address_space *mapping = &ii->i_btnode_cache;
751         struct pagevec pvec;
752         struct buffer_head *bh, *head;
753         unsigned int i;
754         pgoff_t index = 0;
755 
756         pagevec_init(&pvec);
757 
758         while (pagevec_lookup_tag(&pvec, mapping, &index,
759                                         PAGECACHE_TAG_DIRTY)) {
760                 for (i = 0; i < pagevec_count(&pvec); i++) {
761                         bh = head = page_buffers(pvec.pages[i]);
762                         do {
763                                 if (buffer_dirty(bh) &&
764                                                 !buffer_async_write(bh)) {
765                                         get_bh(bh);
766                                         list_add_tail(&bh->b_assoc_buffers,
767                                                       listp);
768                                 }
769                                 bh = bh->b_this_page;
770                         } while (bh != head);
771                 }
772                 pagevec_release(&pvec);
773                 cond_resched();
774         }
775 }
776 
777 static void nilfs_dispose_list(struct the_nilfs *nilfs,
778                                struct list_head *head, int force)
779 {
780         struct nilfs_inode_info *ii, *n;
781         struct nilfs_inode_info *ivec[SC_N_INODEVEC], **pii;
782         unsigned int nv = 0;
783 
784         while (!list_empty(head)) {
785                 spin_lock(&nilfs->ns_inode_lock);
786                 list_for_each_entry_safe(ii, n, head, i_dirty) {
787                         list_del_init(&ii->i_dirty);
788                         if (force) {
789                                 if (unlikely(ii->i_bh)) {
790                                         brelse(ii->i_bh);
791                                         ii->i_bh = NULL;
792                                 }
793                         } else if (test_bit(NILFS_I_DIRTY, &ii->i_state)) {
794                                 set_bit(NILFS_I_QUEUED, &ii->i_state);
795                                 list_add_tail(&ii->i_dirty,
796                                               &nilfs->ns_dirty_files);
797                                 continue;
798                         }
799                         ivec[nv++] = ii;
800                         if (nv == SC_N_INODEVEC)
801                                 break;
802                 }
803                 spin_unlock(&nilfs->ns_inode_lock);
804 
805                 for (pii = ivec; nv > 0; pii++, nv--)
806                         iput(&(*pii)->vfs_inode);
807         }
808 }
809 
810 static void nilfs_iput_work_func(struct work_struct *work)
811 {
812         struct nilfs_sc_info *sci = container_of(work, struct nilfs_sc_info,
813                                                  sc_iput_work);
814         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
815 
816         nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 0);
817 }
818 
819 static int nilfs_test_metadata_dirty(struct the_nilfs *nilfs,
820                                      struct nilfs_root *root)
821 {
822         int ret = 0;
823 
824         if (nilfs_mdt_fetch_dirty(root->ifile))
825                 ret++;
826         if (nilfs_mdt_fetch_dirty(nilfs->ns_cpfile))
827                 ret++;
828         if (nilfs_mdt_fetch_dirty(nilfs->ns_sufile))
829                 ret++;
830         if ((ret || nilfs_doing_gc()) && nilfs_mdt_fetch_dirty(nilfs->ns_dat))
831                 ret++;
832         return ret;
833 }
834 
835 static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
836 {
837         return list_empty(&sci->sc_dirty_files) &&
838                 !test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
839                 sci->sc_nfreesegs == 0 &&
840                 (!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
841 }
842 
843 static int nilfs_segctor_confirm(struct nilfs_sc_info *sci)
844 {
845         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
846         int ret = 0;
847 
848         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
849                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
850 
851         spin_lock(&nilfs->ns_inode_lock);
852         if (list_empty(&nilfs->ns_dirty_files) && nilfs_segctor_clean(sci))
853                 ret++;
854 
855         spin_unlock(&nilfs->ns_inode_lock);
856         return ret;
857 }
858 
859 static void nilfs_segctor_clear_metadata_dirty(struct nilfs_sc_info *sci)
860 {
861         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
862 
863         nilfs_mdt_clear_dirty(sci->sc_root->ifile);
864         nilfs_mdt_clear_dirty(nilfs->ns_cpfile);
865         nilfs_mdt_clear_dirty(nilfs->ns_sufile);
866         nilfs_mdt_clear_dirty(nilfs->ns_dat);
867 }
868 
869 static int nilfs_segctor_create_checkpoint(struct nilfs_sc_info *sci)
870 {
871         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
872         struct buffer_head *bh_cp;
873         struct nilfs_checkpoint *raw_cp;
874         int err;
875 
876         /* XXX: this interface will be changed */
877         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 1,
878                                           &raw_cp, &bh_cp);
879         if (likely(!err)) {
880                 /*
881                  * The following code is duplicated with cpfile.  But, it is
882                  * needed to collect the checkpoint even if it was not newly
883                  * created.
884                  */
885                 mark_buffer_dirty(bh_cp);
886                 nilfs_mdt_mark_dirty(nilfs->ns_cpfile);
887                 nilfs_cpfile_put_checkpoint(
888                         nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
889         } else
890                 WARN_ON(err == -EINVAL || err == -ENOENT);
891 
892         return err;
893 }
894 
895 static int nilfs_segctor_fill_in_checkpoint(struct nilfs_sc_info *sci)
896 {
897         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
898         struct buffer_head *bh_cp;
899         struct nilfs_checkpoint *raw_cp;
900         int err;
901 
902         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, 0,
903                                           &raw_cp, &bh_cp);
904         if (unlikely(err)) {
905                 WARN_ON(err == -EINVAL || err == -ENOENT);
906                 goto failed_ibh;
907         }
908         raw_cp->cp_snapshot_list.ssl_next = 0;
909         raw_cp->cp_snapshot_list.ssl_prev = 0;
910         raw_cp->cp_inodes_count =
911                 cpu_to_le64(atomic64_read(&sci->sc_root->inodes_count));
912         raw_cp->cp_blocks_count =
913                 cpu_to_le64(atomic64_read(&sci->sc_root->blocks_count));
914         raw_cp->cp_nblk_inc =
915                 cpu_to_le64(sci->sc_nblk_inc + sci->sc_nblk_this_inc);
916         raw_cp->cp_create = cpu_to_le64(sci->sc_seg_ctime);
917         raw_cp->cp_cno = cpu_to_le64(nilfs->ns_cno);
918 
919         if (test_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags))
920                 nilfs_checkpoint_clear_minor(raw_cp);
921         else
922                 nilfs_checkpoint_set_minor(raw_cp);
923 
924         nilfs_write_inode_common(sci->sc_root->ifile,
925                                  &raw_cp->cp_ifile_inode, 1);
926         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, nilfs->ns_cno, bh_cp);
927         return 0;
928 
929  failed_ibh:
930         return err;
931 }
932 
933 static void nilfs_fill_in_file_bmap(struct inode *ifile,
934                                     struct nilfs_inode_info *ii)
935 
936 {
937         struct buffer_head *ibh;
938         struct nilfs_inode *raw_inode;
939 
940         if (test_bit(NILFS_I_BMAP, &ii->i_state)) {
941                 ibh = ii->i_bh;
942                 BUG_ON(!ibh);
943                 raw_inode = nilfs_ifile_map_inode(ifile, ii->vfs_inode.i_ino,
944                                                   ibh);
945                 nilfs_bmap_write(ii->i_bmap, raw_inode);
946                 nilfs_ifile_unmap_inode(ifile, ii->vfs_inode.i_ino, ibh);
947         }
948 }
949 
950 static void nilfs_segctor_fill_in_file_bmap(struct nilfs_sc_info *sci)
951 {
952         struct nilfs_inode_info *ii;
953 
954         list_for_each_entry(ii, &sci->sc_dirty_files, i_dirty) {
955                 nilfs_fill_in_file_bmap(sci->sc_root->ifile, ii);
956                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
957         }
958 }
959 
960 static void nilfs_segctor_fill_in_super_root(struct nilfs_sc_info *sci,
961                                              struct the_nilfs *nilfs)
962 {
963         struct buffer_head *bh_sr;
964         struct nilfs_super_root *raw_sr;
965         unsigned int isz, srsz;
966 
967         bh_sr = NILFS_LAST_SEGBUF(&sci->sc_segbufs)->sb_super_root;
968         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
969         isz = nilfs->ns_inode_size;
970         srsz = NILFS_SR_BYTES(isz);
971 
972         raw_sr->sr_bytes = cpu_to_le16(srsz);
973         raw_sr->sr_nongc_ctime
974                 = cpu_to_le64(nilfs_doing_gc() ?
975                               nilfs->ns_nongc_ctime : sci->sc_seg_ctime);
976         raw_sr->sr_flags = 0;
977 
978         nilfs_write_inode_common(nilfs->ns_dat, (void *)raw_sr +
979                                  NILFS_SR_DAT_OFFSET(isz), 1);
980         nilfs_write_inode_common(nilfs->ns_cpfile, (void *)raw_sr +
981                                  NILFS_SR_CPFILE_OFFSET(isz), 1);
982         nilfs_write_inode_common(nilfs->ns_sufile, (void *)raw_sr +
983                                  NILFS_SR_SUFILE_OFFSET(isz), 1);
984         memset((void *)raw_sr + srsz, 0, nilfs->ns_blocksize - srsz);
985 }
986 
987 static void nilfs_redirty_inodes(struct list_head *head)
988 {
989         struct nilfs_inode_info *ii;
990 
991         list_for_each_entry(ii, head, i_dirty) {
992                 if (test_bit(NILFS_I_COLLECTED, &ii->i_state))
993                         clear_bit(NILFS_I_COLLECTED, &ii->i_state);
994         }
995 }
996 
997 static void nilfs_drop_collected_inodes(struct list_head *head)
998 {
999         struct nilfs_inode_info *ii;
1000 
1001         list_for_each_entry(ii, head, i_dirty) {
1002                 if (!test_and_clear_bit(NILFS_I_COLLECTED, &ii->i_state))
1003                         continue;
1004 
1005                 clear_bit(NILFS_I_INODE_SYNC, &ii->i_state);
1006                 set_bit(NILFS_I_UPDATED, &ii->i_state);
1007         }
1008 }
1009 
1010 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
1011                                        struct inode *inode,
1012                                        struct list_head *listp,
1013                                        int (*collect)(struct nilfs_sc_info *,
1014                                                       struct buffer_head *,
1015                                                       struct inode *))
1016 {
1017         struct buffer_head *bh, *n;
1018         int err = 0;
1019 
1020         if (collect) {
1021                 list_for_each_entry_safe(bh, n, listp, b_assoc_buffers) {
1022                         list_del_init(&bh->b_assoc_buffers);
1023                         err = collect(sci, bh, inode);
1024                         brelse(bh);
1025                         if (unlikely(err))
1026                                 goto dispose_buffers;
1027                 }
1028                 return 0;
1029         }
1030 
1031  dispose_buffers:
1032         while (!list_empty(listp)) {
1033                 bh = list_first_entry(listp, struct buffer_head,
1034                                       b_assoc_buffers);
1035                 list_del_init(&bh->b_assoc_buffers);
1036                 brelse(bh);
1037         }
1038         return err;
1039 }
1040 
1041 static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
1042 {
1043         /* Remaining number of blocks within segment buffer */
1044         return sci->sc_segbuf_nblocks -
1045                 (sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
1046 }
1047 
1048 static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
1049                                    struct inode *inode,
1050                                    const struct nilfs_sc_operations *sc_ops)
1051 {
1052         LIST_HEAD(data_buffers);
1053         LIST_HEAD(node_buffers);
1054         int err;
1055 
1056         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1057                 size_t n, rest = nilfs_segctor_buffer_rest(sci);
1058 
1059                 n = nilfs_lookup_dirty_data_buffers(
1060                         inode, &data_buffers, rest + 1, 0, LLONG_MAX);
1061                 if (n > rest) {
1062                         err = nilfs_segctor_apply_buffers(
1063                                 sci, inode, &data_buffers,
1064                                 sc_ops->collect_data);
1065                         BUG_ON(!err); /* always receive -E2BIG or true error */
1066                         goto break_or_fail;
1067                 }
1068         }
1069         nilfs_lookup_dirty_node_buffers(inode, &node_buffers);
1070 
1071         if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
1072                 err = nilfs_segctor_apply_buffers(
1073                         sci, inode, &data_buffers, sc_ops->collect_data);
1074                 if (unlikely(err)) {
1075                         /* dispose node list */
1076                         nilfs_segctor_apply_buffers(
1077                                 sci, inode, &node_buffers, NULL);
1078                         goto break_or_fail;
1079                 }
1080                 sci->sc_stage.flags |= NILFS_CF_NODE;
1081         }
1082         /* Collect node */
1083         err = nilfs_segctor_apply_buffers(
1084                 sci, inode, &node_buffers, sc_ops->collect_node);
1085         if (unlikely(err))
1086                 goto break_or_fail;
1087 
1088         nilfs_bmap_lookup_dirty_buffers(NILFS_I(inode)->i_bmap, &node_buffers);
1089         err = nilfs_segctor_apply_buffers(
1090                 sci, inode, &node_buffers, sc_ops->collect_bmap);
1091         if (unlikely(err))
1092                 goto break_or_fail;
1093 
1094         nilfs_segctor_end_finfo(sci, inode);
1095         sci->sc_stage.flags &= ~NILFS_CF_NODE;
1096 
1097  break_or_fail:
1098         return err;
1099 }
1100 
1101 static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
1102                                          struct inode *inode)
1103 {
1104         LIST_HEAD(data_buffers);
1105         size_t n, rest = nilfs_segctor_buffer_rest(sci);
1106         int err;
1107 
1108         n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
1109                                             sci->sc_dsync_start,
1110                                             sci->sc_dsync_end);
1111 
1112         err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
1113                                           nilfs_collect_file_data);
1114         if (!err) {
1115                 nilfs_segctor_end_finfo(sci, inode);
1116                 BUG_ON(n > rest);
1117                 /* always receive -E2BIG or true error if n > rest */
1118         }
1119         return err;
1120 }
1121 
1122 static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
1123 {
1124         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1125         struct list_head *head;
1126         struct nilfs_inode_info *ii;
1127         size_t ndone;
1128         int err = 0;
1129 
1130         switch (nilfs_sc_cstage_get(sci)) {
1131         case NILFS_ST_INIT:
1132                 /* Pre-processes */
1133                 sci->sc_stage.flags = 0;
1134 
1135                 if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags)) {
1136                         sci->sc_nblk_inc = 0;
1137                         sci->sc_curseg->sb_sum.flags = NILFS_SS_LOGBGN;
1138                         if (mode == SC_LSEG_DSYNC) {
1139                                 nilfs_sc_cstage_set(sci, NILFS_ST_DSYNC);
1140                                 goto dsync_mode;
1141                         }
1142                 }
1143 
1144                 sci->sc_stage.dirty_file_ptr = NULL;
1145                 sci->sc_stage.gc_inode_ptr = NULL;
1146                 if (mode == SC_FLUSH_DAT) {
1147                         nilfs_sc_cstage_set(sci, NILFS_ST_DAT);
1148                         goto dat_stage;
1149                 }
1150                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1151         case NILFS_ST_GC:
1152                 if (nilfs_doing_gc()) {
1153                         head = &sci->sc_gc_inodes;
1154                         ii = list_prepare_entry(sci->sc_stage.gc_inode_ptr,
1155                                                 head, i_dirty);
1156                         list_for_each_entry_continue(ii, head, i_dirty) {
1157                                 err = nilfs_segctor_scan_file(
1158                                         sci, &ii->vfs_inode,
1159                                         &nilfs_sc_file_ops);
1160                                 if (unlikely(err)) {
1161                                         sci->sc_stage.gc_inode_ptr = list_entry(
1162                                                 ii->i_dirty.prev,
1163                                                 struct nilfs_inode_info,
1164                                                 i_dirty);
1165                                         goto break_or_fail;
1166                                 }
1167                                 set_bit(NILFS_I_COLLECTED, &ii->i_state);
1168                         }
1169                         sci->sc_stage.gc_inode_ptr = NULL;
1170                 }
1171                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1172         case NILFS_ST_FILE:
1173                 head = &sci->sc_dirty_files;
1174                 ii = list_prepare_entry(sci->sc_stage.dirty_file_ptr, head,
1175                                         i_dirty);
1176                 list_for_each_entry_continue(ii, head, i_dirty) {
1177                         clear_bit(NILFS_I_DIRTY, &ii->i_state);
1178 
1179                         err = nilfs_segctor_scan_file(sci, &ii->vfs_inode,
1180                                                       &nilfs_sc_file_ops);
1181                         if (unlikely(err)) {
1182                                 sci->sc_stage.dirty_file_ptr =
1183                                         list_entry(ii->i_dirty.prev,
1184                                                    struct nilfs_inode_info,
1185                                                    i_dirty);
1186                                 goto break_or_fail;
1187                         }
1188                         /* sci->sc_stage.dirty_file_ptr = NILFS_I(inode); */
1189                         /* XXX: required ? */
1190                 }
1191                 sci->sc_stage.dirty_file_ptr = NULL;
1192                 if (mode == SC_FLUSH_FILE) {
1193                         nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1194                         return 0;
1195                 }
1196                 nilfs_sc_cstage_inc(sci);
1197                 sci->sc_stage.flags |= NILFS_CF_IFILE_STARTED;
1198                 /* Fall through */
1199         case NILFS_ST_IFILE:
1200                 err = nilfs_segctor_scan_file(sci, sci->sc_root->ifile,
1201                                               &nilfs_sc_file_ops);
1202                 if (unlikely(err))
1203                         break;
1204                 nilfs_sc_cstage_inc(sci);
1205                 /* Creating a checkpoint */
1206                 err = nilfs_segctor_create_checkpoint(sci);
1207                 if (unlikely(err))
1208                         break;
1209                 /* Fall through */
1210         case NILFS_ST_CPFILE:
1211                 err = nilfs_segctor_scan_file(sci, nilfs->ns_cpfile,
1212                                               &nilfs_sc_file_ops);
1213                 if (unlikely(err))
1214                         break;
1215                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1216         case NILFS_ST_SUFILE:
1217                 err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
1218                                          sci->sc_nfreesegs, &ndone);
1219                 if (unlikely(err)) {
1220                         nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1221                                                   sci->sc_freesegs, ndone,
1222                                                   NULL);
1223                         break;
1224                 }
1225                 sci->sc_stage.flags |= NILFS_CF_SUFREED;
1226 
1227                 err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
1228                                               &nilfs_sc_file_ops);
1229                 if (unlikely(err))
1230                         break;
1231                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1232         case NILFS_ST_DAT:
1233  dat_stage:
1234                 err = nilfs_segctor_scan_file(sci, nilfs->ns_dat,
1235                                               &nilfs_sc_dat_ops);
1236                 if (unlikely(err))
1237                         break;
1238                 if (mode == SC_FLUSH_DAT) {
1239                         nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1240                         return 0;
1241                 }
1242                 nilfs_sc_cstage_inc(sci);  /* Fall through */
1243         case NILFS_ST_SR:
1244                 if (mode == SC_LSEG_SR) {
1245                         /* Appending a super root */
1246                         err = nilfs_segctor_add_super_root(sci);
1247                         if (unlikely(err))
1248                                 break;
1249                 }
1250                 /* End of a logical segment */
1251                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1252                 nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1253                 return 0;
1254         case NILFS_ST_DSYNC:
1255  dsync_mode:
1256                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
1257                 ii = sci->sc_dsync_inode;
1258                 if (!test_bit(NILFS_I_BUSY, &ii->i_state))
1259                         break;
1260 
1261                 err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
1262                 if (unlikely(err))
1263                         break;
1264                 sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
1265                 nilfs_sc_cstage_set(sci, NILFS_ST_DONE);
1266                 return 0;
1267         case NILFS_ST_DONE:
1268                 return 0;
1269         default:
1270                 BUG();
1271         }
1272 
1273  break_or_fail:
1274         return err;
1275 }
1276 
1277 /**
1278  * nilfs_segctor_begin_construction - setup segment buffer to make a new log
1279  * @sci: nilfs_sc_info
1280  * @nilfs: nilfs object
1281  */
1282 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
1283                                             struct the_nilfs *nilfs)
1284 {
1285         struct nilfs_segment_buffer *segbuf, *prev;
1286         __u64 nextnum;
1287         int err, alloc = 0;
1288 
1289         segbuf = nilfs_segbuf_new(sci->sc_super);
1290         if (unlikely(!segbuf))
1291                 return -ENOMEM;
1292 
1293         if (list_empty(&sci->sc_write_logs)) {
1294                 nilfs_segbuf_map(segbuf, nilfs->ns_segnum,
1295                                  nilfs->ns_pseg_offset, nilfs);
1296                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1297                         nilfs_shift_to_next_segment(nilfs);
1298                         nilfs_segbuf_map(segbuf, nilfs->ns_segnum, 0, nilfs);
1299                 }
1300 
1301                 segbuf->sb_sum.seg_seq = nilfs->ns_seg_seq;
1302                 nextnum = nilfs->ns_nextnum;
1303 
1304                 if (nilfs->ns_segnum == nilfs->ns_nextnum)
1305                         /* Start from the head of a new full segment */
1306                         alloc++;
1307         } else {
1308                 /* Continue logs */
1309                 prev = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1310                 nilfs_segbuf_map_cont(segbuf, prev);
1311                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq;
1312                 nextnum = prev->sb_nextnum;
1313 
1314                 if (segbuf->sb_rest_blocks < NILFS_PSEG_MIN_BLOCKS) {
1315                         nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1316                         segbuf->sb_sum.seg_seq++;
1317                         alloc++;
1318                 }
1319         }
1320 
1321         err = nilfs_sufile_mark_dirty(nilfs->ns_sufile, segbuf->sb_segnum);
1322         if (err)
1323                 goto failed;
1324 
1325         if (alloc) {
1326                 err = nilfs_sufile_alloc(nilfs->ns_sufile, &nextnum);
1327                 if (err)
1328                         goto failed;
1329         }
1330         nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
1331 
1332         BUG_ON(!list_empty(&sci->sc_segbufs));
1333         list_add_tail(&segbuf->sb_list, &sci->sc_segbufs);
1334         sci->sc_segbuf_nblocks = segbuf->sb_rest_blocks;
1335         return 0;
1336 
1337  failed:
1338         nilfs_segbuf_free(segbuf);
1339         return err;
1340 }
1341 
1342 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
1343                                          struct the_nilfs *nilfs, int nadd)
1344 {
1345         struct nilfs_segment_buffer *segbuf, *prev;
1346         struct inode *sufile = nilfs->ns_sufile;
1347         __u64 nextnextnum;
1348         LIST_HEAD(list);
1349         int err, ret, i;
1350 
1351         prev = NILFS_LAST_SEGBUF(&sci->sc_segbufs);
1352         /*
1353          * Since the segment specified with nextnum might be allocated during
1354          * the previous construction, the buffer including its segusage may
1355          * not be dirty.  The following call ensures that the buffer is dirty
1356          * and will pin the buffer on memory until the sufile is written.
1357          */
1358         err = nilfs_sufile_mark_dirty(sufile, prev->sb_nextnum);
1359         if (unlikely(err))
1360                 return err;
1361 
1362         for (i = 0; i < nadd; i++) {
1363                 /* extend segment info */
1364                 err = -ENOMEM;
1365                 segbuf = nilfs_segbuf_new(sci->sc_super);
1366                 if (unlikely(!segbuf))
1367                         goto failed;
1368 
1369                 /* map this buffer to region of segment on-disk */
1370                 nilfs_segbuf_map(segbuf, prev->sb_nextnum, 0, nilfs);
1371                 sci->sc_segbuf_nblocks += segbuf->sb_rest_blocks;
1372 
1373                 /* allocate the next next full segment */
1374                 err = nilfs_sufile_alloc(sufile, &nextnextnum);
1375                 if (unlikely(err))
1376                         goto failed_segbuf;
1377 
1378                 segbuf->sb_sum.seg_seq = prev->sb_sum.seg_seq + 1;
1379                 nilfs_segbuf_set_next_segnum(segbuf, nextnextnum, nilfs);
1380 
1381                 list_add_tail(&segbuf->sb_list, &list);
1382                 prev = segbuf;
1383         }
1384         list_splice_tail(&list, &sci->sc_segbufs);
1385         return 0;
1386 
1387  failed_segbuf:
1388         nilfs_segbuf_free(segbuf);
1389  failed:
1390         list_for_each_entry(segbuf, &list, sb_list) {
1391                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1392                 WARN_ON(ret); /* never fails */
1393         }
1394         nilfs_destroy_logs(&list);
1395         return err;
1396 }
1397 
1398 static void nilfs_free_incomplete_logs(struct list_head *logs,
1399                                        struct the_nilfs *nilfs)
1400 {
1401         struct nilfs_segment_buffer *segbuf, *prev;
1402         struct inode *sufile = nilfs->ns_sufile;
1403         int ret;
1404 
1405         segbuf = NILFS_FIRST_SEGBUF(logs);
1406         if (nilfs->ns_nextnum != segbuf->sb_nextnum) {
1407                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1408                 WARN_ON(ret); /* never fails */
1409         }
1410         if (atomic_read(&segbuf->sb_err)) {
1411                 /* Case 1: The first segment failed */
1412                 if (segbuf->sb_pseg_start != segbuf->sb_fseg_start)
1413                         /*
1414                          * Case 1a:  Partial segment appended into an existing
1415                          * segment
1416                          */
1417                         nilfs_terminate_segment(nilfs, segbuf->sb_fseg_start,
1418                                                 segbuf->sb_fseg_end);
1419                 else /* Case 1b:  New full segment */
1420                         set_nilfs_discontinued(nilfs);
1421         }
1422 
1423         prev = segbuf;
1424         list_for_each_entry_continue(segbuf, logs, sb_list) {
1425                 if (prev->sb_nextnum != segbuf->sb_nextnum) {
1426                         ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1427                         WARN_ON(ret); /* never fails */
1428                 }
1429                 if (atomic_read(&segbuf->sb_err) &&
1430                     segbuf->sb_segnum != nilfs->ns_nextnum)
1431                         /* Case 2: extended segment (!= next) failed */
1432                         nilfs_sufile_set_error(sufile, segbuf->sb_segnum);
1433                 prev = segbuf;
1434         }
1435 }
1436 
1437 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
1438                                           struct inode *sufile)
1439 {
1440         struct nilfs_segment_buffer *segbuf;
1441         unsigned long live_blocks;
1442         int ret;
1443 
1444         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1445                 live_blocks = segbuf->sb_sum.nblocks +
1446                         (segbuf->sb_pseg_start - segbuf->sb_fseg_start);
1447                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1448                                                      live_blocks,
1449                                                      sci->sc_seg_ctime);
1450                 WARN_ON(ret); /* always succeed because the segusage is dirty */
1451         }
1452 }
1453 
1454 static void nilfs_cancel_segusage(struct list_head *logs, struct inode *sufile)
1455 {
1456         struct nilfs_segment_buffer *segbuf;
1457         int ret;
1458 
1459         segbuf = NILFS_FIRST_SEGBUF(logs);
1460         ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1461                                              segbuf->sb_pseg_start -
1462                                              segbuf->sb_fseg_start, 0);
1463         WARN_ON(ret); /* always succeed because the segusage is dirty */
1464 
1465         list_for_each_entry_continue(segbuf, logs, sb_list) {
1466                 ret = nilfs_sufile_set_segment_usage(sufile, segbuf->sb_segnum,
1467                                                      0, 0);
1468                 WARN_ON(ret); /* always succeed */
1469         }
1470 }
1471 
1472 static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
1473                                             struct nilfs_segment_buffer *last,
1474                                             struct inode *sufile)
1475 {
1476         struct nilfs_segment_buffer *segbuf = last;
1477         int ret;
1478 
1479         list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
1480                 sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
1481                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
1482                 WARN_ON(ret);
1483         }
1484         nilfs_truncate_logs(&sci->sc_segbufs, last);
1485 }
1486 
1487 
1488 static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
1489                                  struct the_nilfs *nilfs, int mode)
1490 {
1491         struct nilfs_cstage prev_stage = sci->sc_stage;
1492         int err, nadd = 1;
1493 
1494         /* Collection retry loop */
1495         for (;;) {
1496                 sci->sc_nblk_this_inc = 0;
1497                 sci->sc_curseg = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
1498 
1499                 err = nilfs_segctor_reset_segment_buffer(sci);
1500                 if (unlikely(err))
1501                         goto failed;
1502 
1503                 err = nilfs_segctor_collect_blocks(sci, mode);
1504                 sci->sc_nblk_this_inc += sci->sc_curseg->sb_sum.nblocks;
1505                 if (!err)
1506                         break;
1507 
1508                 if (unlikely(err != -E2BIG))
1509                         goto failed;
1510 
1511                 /* The current segment is filled up */
1512                 if (mode != SC_LSEG_SR ||
1513                     nilfs_sc_cstage_get(sci) < NILFS_ST_CPFILE)
1514                         break;
1515 
1516                 nilfs_clear_logs(&sci->sc_segbufs);
1517 
1518                 if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1519                         err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1520                                                         sci->sc_freesegs,
1521                                                         sci->sc_nfreesegs,
1522                                                         NULL);
1523                         WARN_ON(err); /* do not happen */
1524                         sci->sc_stage.flags &= ~NILFS_CF_SUFREED;
1525                 }
1526 
1527                 err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
1528                 if (unlikely(err))
1529                         return err;
1530 
1531                 nadd = min_t(int, nadd << 1, SC_MAX_SEGDELTA);
1532                 sci->sc_stage = prev_stage;
1533         }
1534         nilfs_segctor_truncate_segments(sci, sci->sc_curseg, nilfs->ns_sufile);
1535         return 0;
1536 
1537  failed:
1538         return err;
1539 }
1540 
1541 static void nilfs_list_replace_buffer(struct buffer_head *old_bh,
1542                                       struct buffer_head *new_bh)
1543 {
1544         BUG_ON(!list_empty(&new_bh->b_assoc_buffers));
1545 
1546         list_replace_init(&old_bh->b_assoc_buffers, &new_bh->b_assoc_buffers);
1547         /* The caller must release old_bh */
1548 }
1549 
1550 static int
1551 nilfs_segctor_update_payload_blocknr(struct nilfs_sc_info *sci,
1552                                      struct nilfs_segment_buffer *segbuf,
1553                                      int mode)
1554 {
1555         struct inode *inode = NULL;
1556         sector_t blocknr;
1557         unsigned long nfinfo = segbuf->sb_sum.nfinfo;
1558         unsigned long nblocks = 0, ndatablk = 0;
1559         const struct nilfs_sc_operations *sc_op = NULL;
1560         struct nilfs_segsum_pointer ssp;
1561         struct nilfs_finfo *finfo = NULL;
1562         union nilfs_binfo binfo;
1563         struct buffer_head *bh, *bh_org;
1564         ino_t ino = 0;
1565         int err = 0;
1566 
1567         if (!nfinfo)
1568                 goto out;
1569 
1570         blocknr = segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk;
1571         ssp.bh = NILFS_SEGBUF_FIRST_BH(&segbuf->sb_segsum_buffers);
1572         ssp.offset = sizeof(struct nilfs_segment_summary);
1573 
1574         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
1575                 if (bh == segbuf->sb_super_root)
1576                         break;
1577                 if (!finfo) {
1578                         finfo = nilfs_segctor_map_segsum_entry(
1579                                 sci, &ssp, sizeof(*finfo));
1580                         ino = le64_to_cpu(finfo->fi_ino);
1581                         nblocks = le32_to_cpu(finfo->fi_nblocks);
1582                         ndatablk = le32_to_cpu(finfo->fi_ndatablk);
1583 
1584                         inode = bh->b_page->mapping->host;
1585 
1586                         if (mode == SC_LSEG_DSYNC)
1587                                 sc_op = &nilfs_sc_dsync_ops;
1588                         else if (ino == NILFS_DAT_INO)
1589                                 sc_op = &nilfs_sc_dat_ops;
1590                         else /* file blocks */
1591                                 sc_op = &nilfs_sc_file_ops;
1592                 }
1593                 bh_org = bh;
1594                 get_bh(bh_org);
1595                 err = nilfs_bmap_assign(NILFS_I(inode)->i_bmap, &bh, blocknr,
1596                                         &binfo);
1597                 if (bh != bh_org)
1598                         nilfs_list_replace_buffer(bh_org, bh);
1599                 brelse(bh_org);
1600                 if (unlikely(err))
1601                         goto failed_bmap;
1602 
1603                 if (ndatablk > 0)
1604                         sc_op->write_data_binfo(sci, &ssp, &binfo);
1605                 else
1606                         sc_op->write_node_binfo(sci, &ssp, &binfo);
1607 
1608                 blocknr++;
1609                 if (--nblocks == 0) {
1610                         finfo = NULL;
1611                         if (--nfinfo == 0)
1612                                 break;
1613                 } else if (ndatablk > 0)
1614                         ndatablk--;
1615         }
1616  out:
1617         return 0;
1618 
1619  failed_bmap:
1620         return err;
1621 }
1622 
1623 static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
1624 {
1625         struct nilfs_segment_buffer *segbuf;
1626         int err;
1627 
1628         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1629                 err = nilfs_segctor_update_payload_blocknr(sci, segbuf, mode);
1630                 if (unlikely(err))
1631                         return err;
1632                 nilfs_segbuf_fill_in_segsum(segbuf);
1633         }
1634         return 0;
1635 }
1636 
1637 static void nilfs_begin_page_io(struct page *page)
1638 {
1639         if (!page || PageWriteback(page))
1640                 /*
1641                  * For split b-tree node pages, this function may be called
1642                  * twice.  We ignore the 2nd or later calls by this check.
1643                  */
1644                 return;
1645 
1646         lock_page(page);
1647         clear_page_dirty_for_io(page);
1648         set_page_writeback(page);
1649         unlock_page(page);
1650 }
1651 
1652 static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
1653 {
1654         struct nilfs_segment_buffer *segbuf;
1655         struct page *bd_page = NULL, *fs_page = NULL;
1656 
1657         list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
1658                 struct buffer_head *bh;
1659 
1660                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1661                                     b_assoc_buffers) {
1662                         if (bh->b_page != bd_page) {
1663                                 if (bd_page) {
1664                                         lock_page(bd_page);
1665                                         clear_page_dirty_for_io(bd_page);
1666                                         set_page_writeback(bd_page);
1667                                         unlock_page(bd_page);
1668                                 }
1669                                 bd_page = bh->b_page;
1670                         }
1671                 }
1672 
1673                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1674                                     b_assoc_buffers) {
1675                         set_buffer_async_write(bh);
1676                         if (bh == segbuf->sb_super_root) {
1677                                 if (bh->b_page != bd_page) {
1678                                         lock_page(bd_page);
1679                                         clear_page_dirty_for_io(bd_page);
1680                                         set_page_writeback(bd_page);
1681                                         unlock_page(bd_page);
1682                                         bd_page = bh->b_page;
1683                                 }
1684                                 break;
1685                         }
1686                         if (bh->b_page != fs_page) {
1687                                 nilfs_begin_page_io(fs_page);
1688                                 fs_page = bh->b_page;
1689                         }
1690                 }
1691         }
1692         if (bd_page) {
1693                 lock_page(bd_page);
1694                 clear_page_dirty_for_io(bd_page);
1695                 set_page_writeback(bd_page);
1696                 unlock_page(bd_page);
1697         }
1698         nilfs_begin_page_io(fs_page);
1699 }
1700 
1701 static int nilfs_segctor_write(struct nilfs_sc_info *sci,
1702                                struct the_nilfs *nilfs)
1703 {
1704         int ret;
1705 
1706         ret = nilfs_write_logs(&sci->sc_segbufs, nilfs);
1707         list_splice_tail_init(&sci->sc_segbufs, &sci->sc_write_logs);
1708         return ret;
1709 }
1710 
1711 static void nilfs_end_page_io(struct page *page, int err)
1712 {
1713         if (!page)
1714                 return;
1715 
1716         if (buffer_nilfs_node(page_buffers(page)) && !PageWriteback(page)) {
1717                 /*
1718                  * For b-tree node pages, this function may be called twice
1719                  * or more because they might be split in a segment.
1720                  */
1721                 if (PageDirty(page)) {
1722                         /*
1723                          * For pages holding split b-tree node buffers, dirty
1724                          * flag on the buffers may be cleared discretely.
1725                          * In that case, the page is once redirtied for
1726                          * remaining buffers, and it must be cancelled if
1727                          * all the buffers get cleaned later.
1728                          */
1729                         lock_page(page);
1730                         if (nilfs_page_buffers_clean(page))
1731                                 __nilfs_clear_page_dirty(page);
1732                         unlock_page(page);
1733                 }
1734                 return;
1735         }
1736 
1737         if (!err) {
1738                 if (!nilfs_page_buffers_clean(page))
1739                         __set_page_dirty_nobuffers(page);
1740                 ClearPageError(page);
1741         } else {
1742                 __set_page_dirty_nobuffers(page);
1743                 SetPageError(page);
1744         }
1745 
1746         end_page_writeback(page);
1747 }
1748 
1749 static void nilfs_abort_logs(struct list_head *logs, int err)
1750 {
1751         struct nilfs_segment_buffer *segbuf;
1752         struct page *bd_page = NULL, *fs_page = NULL;
1753         struct buffer_head *bh;
1754 
1755         if (list_empty(logs))
1756                 return;
1757 
1758         list_for_each_entry(segbuf, logs, sb_list) {
1759                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1760                                     b_assoc_buffers) {
1761                         if (bh->b_page != bd_page) {
1762                                 if (bd_page)
1763                                         end_page_writeback(bd_page);
1764                                 bd_page = bh->b_page;
1765                         }
1766                 }
1767 
1768                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1769                                     b_assoc_buffers) {
1770                         clear_buffer_async_write(bh);
1771                         if (bh == segbuf->sb_super_root) {
1772                                 if (bh->b_page != bd_page) {
1773                                         end_page_writeback(bd_page);
1774                                         bd_page = bh->b_page;
1775                                 }
1776                                 break;
1777                         }
1778                         if (bh->b_page != fs_page) {
1779                                 nilfs_end_page_io(fs_page, err);
1780                                 fs_page = bh->b_page;
1781                         }
1782                 }
1783         }
1784         if (bd_page)
1785                 end_page_writeback(bd_page);
1786 
1787         nilfs_end_page_io(fs_page, err);
1788 }
1789 
1790 static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
1791                                              struct the_nilfs *nilfs, int err)
1792 {
1793         LIST_HEAD(logs);
1794         int ret;
1795 
1796         list_splice_tail_init(&sci->sc_write_logs, &logs);
1797         ret = nilfs_wait_on_logs(&logs);
1798         nilfs_abort_logs(&logs, ret ? : err);
1799 
1800         list_splice_tail_init(&sci->sc_segbufs, &logs);
1801         nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
1802         nilfs_free_incomplete_logs(&logs, nilfs);
1803 
1804         if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
1805                 ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
1806                                                 sci->sc_freesegs,
1807                                                 sci->sc_nfreesegs,
1808                                                 NULL);
1809                 WARN_ON(ret); /* do not happen */
1810         }
1811 
1812         nilfs_destroy_logs(&logs);
1813 }
1814 
1815 static void nilfs_set_next_segment(struct the_nilfs *nilfs,
1816                                    struct nilfs_segment_buffer *segbuf)
1817 {
1818         nilfs->ns_segnum = segbuf->sb_segnum;
1819         nilfs->ns_nextnum = segbuf->sb_nextnum;
1820         nilfs->ns_pseg_offset = segbuf->sb_pseg_start - segbuf->sb_fseg_start
1821                 + segbuf->sb_sum.nblocks;
1822         nilfs->ns_seg_seq = segbuf->sb_sum.seg_seq;
1823         nilfs->ns_ctime = segbuf->sb_sum.ctime;
1824 }
1825 
1826 static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
1827 {
1828         struct nilfs_segment_buffer *segbuf;
1829         struct page *bd_page = NULL, *fs_page = NULL;
1830         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
1831         int update_sr = false;
1832 
1833         list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
1834                 struct buffer_head *bh;
1835 
1836                 list_for_each_entry(bh, &segbuf->sb_segsum_buffers,
1837                                     b_assoc_buffers) {
1838                         set_buffer_uptodate(bh);
1839                         clear_buffer_dirty(bh);
1840                         if (bh->b_page != bd_page) {
1841                                 if (bd_page)
1842                                         end_page_writeback(bd_page);
1843                                 bd_page = bh->b_page;
1844                         }
1845                 }
1846                 /*
1847                  * We assume that the buffers which belong to the same page
1848                  * continue over the buffer list.
1849                  * Under this assumption, the last BHs of pages is
1850                  * identifiable by the discontinuity of bh->b_page
1851                  * (page != fs_page).
1852                  *
1853                  * For B-tree node blocks, however, this assumption is not
1854                  * guaranteed.  The cleanup code of B-tree node pages needs
1855                  * special care.
1856                  */
1857                 list_for_each_entry(bh, &segbuf->sb_payload_buffers,
1858                                     b_assoc_buffers) {
1859                         const unsigned long set_bits = BIT(BH_Uptodate);
1860                         const unsigned long clear_bits =
1861                                 (BIT(BH_Dirty) | BIT(BH_Async_Write) |
1862                                  BIT(BH_Delay) | BIT(BH_NILFS_Volatile) |
1863                                  BIT(BH_NILFS_Redirected));
1864 
1865                         set_mask_bits(&bh->b_state, clear_bits, set_bits);
1866                         if (bh == segbuf->sb_super_root) {
1867                                 if (bh->b_page != bd_page) {
1868                                         end_page_writeback(bd_page);
1869                                         bd_page = bh->b_page;
1870                                 }
1871                                 update_sr = true;
1872                                 break;
1873                         }
1874                         if (bh->b_page != fs_page) {
1875                                 nilfs_end_page_io(fs_page, 0);
1876                                 fs_page = bh->b_page;
1877                         }
1878                 }
1879 
1880                 if (!nilfs_segbuf_simplex(segbuf)) {
1881                         if (segbuf->sb_sum.flags & NILFS_SS_LOGBGN) {
1882                                 set_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1883                                 sci->sc_lseg_stime = jiffies;
1884                         }
1885                         if (segbuf->sb_sum.flags & NILFS_SS_LOGEND)
1886                                 clear_bit(NILFS_SC_UNCLOSED, &sci->sc_flags);
1887                 }
1888         }
1889         /*
1890          * Since pages may continue over multiple segment buffers,
1891          * end of the last page must be checked outside of the loop.
1892          */
1893         if (bd_page)
1894                 end_page_writeback(bd_page);
1895 
1896         nilfs_end_page_io(fs_page, 0);
1897 
1898         nilfs_drop_collected_inodes(&sci->sc_dirty_files);
1899 
1900         if (nilfs_doing_gc())
1901                 nilfs_drop_collected_inodes(&sci->sc_gc_inodes);
1902         else
1903                 nilfs->ns_nongc_ctime = sci->sc_seg_ctime;
1904 
1905         sci->sc_nblk_inc += sci->sc_nblk_this_inc;
1906 
1907         segbuf = NILFS_LAST_SEGBUF(&sci->sc_write_logs);
1908         nilfs_set_next_segment(nilfs, segbuf);
1909 
1910         if (update_sr) {
1911                 nilfs->ns_flushed_device = 0;
1912                 nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
1913                                        segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
1914 
1915                 clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
1916                 clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
1917                 set_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1918                 nilfs_segctor_clear_metadata_dirty(sci);
1919         } else
1920                 clear_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags);
1921 }
1922 
1923 static int nilfs_segctor_wait(struct nilfs_sc_info *sci)
1924 {
1925         int ret;
1926 
1927         ret = nilfs_wait_on_logs(&sci->sc_write_logs);
1928         if (!ret) {
1929                 nilfs_segctor_complete_write(sci);
1930                 nilfs_destroy_logs(&sci->sc_write_logs);
1931         }
1932         return ret;
1933 }
1934 
1935 static int nilfs_segctor_collect_dirty_files(struct nilfs_sc_info *sci,
1936                                              struct the_nilfs *nilfs)
1937 {
1938         struct nilfs_inode_info *ii, *n;
1939         struct inode *ifile = sci->sc_root->ifile;
1940 
1941         spin_lock(&nilfs->ns_inode_lock);
1942  retry:
1943         list_for_each_entry_safe(ii, n, &nilfs->ns_dirty_files, i_dirty) {
1944                 if (!ii->i_bh) {
1945                         struct buffer_head *ibh;
1946                         int err;
1947 
1948                         spin_unlock(&nilfs->ns_inode_lock);
1949                         err = nilfs_ifile_get_inode_block(
1950                                 ifile, ii->vfs_inode.i_ino, &ibh);
1951                         if (unlikely(err)) {
1952                                 nilfs_msg(sci->sc_super, KERN_WARNING,
1953                                           "log writer: error %d getting inode block (ino=%lu)",
1954                                           err, ii->vfs_inode.i_ino);
1955                                 return err;
1956                         }
1957                         spin_lock(&nilfs->ns_inode_lock);
1958                         if (likely(!ii->i_bh))
1959                                 ii->i_bh = ibh;
1960                         else
1961                                 brelse(ibh);
1962                         goto retry;
1963                 }
1964 
1965                 // Always redirty the buffer to avoid race condition
1966                 mark_buffer_dirty(ii->i_bh);
1967                 nilfs_mdt_mark_dirty(ifile);
1968 
1969                 clear_bit(NILFS_I_QUEUED, &ii->i_state);
1970                 set_bit(NILFS_I_BUSY, &ii->i_state);
1971                 list_move_tail(&ii->i_dirty, &sci->sc_dirty_files);
1972         }
1973         spin_unlock(&nilfs->ns_inode_lock);
1974 
1975         return 0;
1976 }
1977 
1978 static void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
1979                                              struct the_nilfs *nilfs)
1980 {
1981         struct nilfs_inode_info *ii, *n;
1982         int during_mount = !(sci->sc_super->s_flags & SB_ACTIVE);
1983         int defer_iput = false;
1984 
1985         spin_lock(&nilfs->ns_inode_lock);
1986         list_for_each_entry_safe(ii, n, &sci->sc_dirty_files, i_dirty) {
1987                 if (!test_and_clear_bit(NILFS_I_UPDATED, &ii->i_state) ||
1988                     test_bit(NILFS_I_DIRTY, &ii->i_state))
1989                         continue;
1990 
1991                 clear_bit(NILFS_I_BUSY, &ii->i_state);
1992                 brelse(ii->i_bh);
1993                 ii->i_bh = NULL;
1994                 list_del_init(&ii->i_dirty);
1995                 if (!ii->vfs_inode.i_nlink || during_mount) {
1996                         /*
1997                          * Defer calling iput() to avoid deadlocks if
1998                          * i_nlink == 0 or mount is not yet finished.
1999                          */
2000                         list_add_tail(&ii->i_dirty, &sci->sc_iput_queue);
2001                         defer_iput = true;
2002                 } else {
2003                         spin_unlock(&nilfs->ns_inode_lock);
2004                         iput(&ii->vfs_inode);
2005                         spin_lock(&nilfs->ns_inode_lock);
2006                 }
2007         }
2008         spin_unlock(&nilfs->ns_inode_lock);
2009 
2010         if (defer_iput)
2011                 schedule_work(&sci->sc_iput_work);
2012 }
2013 
2014 /*
2015  * Main procedure of segment constructor
2016  */
2017 static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
2018 {
2019         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2020         int err;
2021 
2022         nilfs_sc_cstage_set(sci, NILFS_ST_INIT);
2023         sci->sc_cno = nilfs->ns_cno;
2024 
2025         err = nilfs_segctor_collect_dirty_files(sci, nilfs);
2026         if (unlikely(err))
2027                 goto out;
2028 
2029         if (nilfs_test_metadata_dirty(nilfs, sci->sc_root))
2030                 set_bit(NILFS_SC_DIRTY, &sci->sc_flags);
2031 
2032         if (nilfs_segctor_clean(sci))
2033                 goto out;
2034 
2035         do {
2036                 sci->sc_stage.flags &= ~NILFS_CF_HISTORY_MASK;
2037 
2038                 err = nilfs_segctor_begin_construction(sci, nilfs);
2039                 if (unlikely(err))
2040                         goto out;
2041 
2042                 /* Update time stamp */
2043                 sci->sc_seg_ctime = ktime_get_real_seconds();
2044 
2045                 err = nilfs_segctor_collect(sci, nilfs, mode);
2046                 if (unlikely(err))
2047                         goto failed;
2048 
2049                 /* Avoid empty segment */
2050                 if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE &&
2051                     nilfs_segbuf_empty(sci->sc_curseg)) {
2052                         nilfs_segctor_abort_construction(sci, nilfs, 1);
2053                         goto out;
2054                 }
2055 
2056                 err = nilfs_segctor_assign(sci, mode);
2057                 if (unlikely(err))
2058                         goto failed;
2059 
2060                 if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2061                         nilfs_segctor_fill_in_file_bmap(sci);
2062 
2063                 if (mode == SC_LSEG_SR &&
2064                     nilfs_sc_cstage_get(sci) >= NILFS_ST_CPFILE) {
2065                         err = nilfs_segctor_fill_in_checkpoint(sci);
2066                         if (unlikely(err))
2067                                 goto failed_to_write;
2068 
2069                         nilfs_segctor_fill_in_super_root(sci, nilfs);
2070                 }
2071                 nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
2072 
2073                 /* Write partial segments */
2074                 nilfs_segctor_prepare_write(sci);
2075 
2076                 nilfs_add_checksums_on_logs(&sci->sc_segbufs,
2077                                             nilfs->ns_crc_seed);
2078 
2079                 err = nilfs_segctor_write(sci, nilfs);
2080                 if (unlikely(err))
2081                         goto failed_to_write;
2082 
2083                 if (nilfs_sc_cstage_get(sci) == NILFS_ST_DONE ||
2084                     nilfs->ns_blocksize_bits != PAGE_SHIFT) {
2085                         /*
2086                          * At this point, we avoid double buffering
2087                          * for blocksize < pagesize because page dirty
2088                          * flag is turned off during write and dirty
2089                          * buffers are not properly collected for
2090                          * pages crossing over segments.
2091                          */
2092                         err = nilfs_segctor_wait(sci);
2093                         if (err)
2094                                 goto failed_to_write;
2095                 }
2096         } while (nilfs_sc_cstage_get(sci) != NILFS_ST_DONE);
2097 
2098  out:
2099         nilfs_segctor_drop_written_files(sci, nilfs);
2100         return err;
2101 
2102  failed_to_write:
2103         if (sci->sc_stage.flags & NILFS_CF_IFILE_STARTED)
2104                 nilfs_redirty_inodes(&sci->sc_dirty_files);
2105 
2106  failed:
2107         if (nilfs_doing_gc())
2108                 nilfs_redirty_inodes(&sci->sc_gc_inodes);
2109         nilfs_segctor_abort_construction(sci, nilfs, err);
2110         goto out;
2111 }
2112 
2113 /**
2114  * nilfs_segctor_start_timer - set timer of background write
2115  * @sci: nilfs_sc_info
2116  *
2117  * If the timer has already been set, it ignores the new request.
2118  * This function MUST be called within a section locking the segment
2119  * semaphore.
2120  */
2121 static void nilfs_segctor_start_timer(struct nilfs_sc_info *sci)
2122 {
2123         spin_lock(&sci->sc_state_lock);
2124         if (!(sci->sc_state & NILFS_SEGCTOR_COMMIT)) {
2125                 sci->sc_timer.expires = jiffies + sci->sc_interval;
2126                 add_timer(&sci->sc_timer);
2127                 sci->sc_state |= NILFS_SEGCTOR_COMMIT;
2128         }
2129         spin_unlock(&sci->sc_state_lock);
2130 }
2131 
2132 static void nilfs_segctor_do_flush(struct nilfs_sc_info *sci, int bn)
2133 {
2134         spin_lock(&sci->sc_state_lock);
2135         if (!(sci->sc_flush_request & BIT(bn))) {
2136                 unsigned long prev_req = sci->sc_flush_request;
2137 
2138                 sci->sc_flush_request |= BIT(bn);
2139                 if (!prev_req)
2140                         wake_up(&sci->sc_wait_daemon);
2141         }
2142         spin_unlock(&sci->sc_state_lock);
2143 }
2144 
2145 /**
2146  * nilfs_flush_segment - trigger a segment construction for resource control
2147  * @sb: super block
2148  * @ino: inode number of the file to be flushed out.
2149  */
2150 void nilfs_flush_segment(struct super_block *sb, ino_t ino)
2151 {
2152         struct the_nilfs *nilfs = sb->s_fs_info;
2153         struct nilfs_sc_info *sci = nilfs->ns_writer;
2154 
2155         if (!sci || nilfs_doing_construction())
2156                 return;
2157         nilfs_segctor_do_flush(sci, NILFS_MDT_INODE(sb, ino) ? ino : 0);
2158                                         /* assign bit 0 to data files */
2159 }
2160 
2161 struct nilfs_segctor_wait_request {
2162         wait_queue_entry_t      wq;
2163         __u32           seq;
2164         int             err;
2165         atomic_t        done;
2166 };
2167 
2168 static int nilfs_segctor_sync(struct nilfs_sc_info *sci)
2169 {
2170         struct nilfs_segctor_wait_request wait_req;
2171         int err = 0;
2172 
2173         spin_lock(&sci->sc_state_lock);
2174         init_wait(&wait_req.wq);
2175         wait_req.err = 0;
2176         atomic_set(&wait_req.done, 0);
2177         wait_req.seq = ++sci->sc_seq_request;
2178         spin_unlock(&sci->sc_state_lock);
2179 
2180         init_waitqueue_entry(&wait_req.wq, current);
2181         add_wait_queue(&sci->sc_wait_request, &wait_req.wq);
2182         set_current_state(TASK_INTERRUPTIBLE);
2183         wake_up(&sci->sc_wait_daemon);
2184 
2185         for (;;) {
2186                 if (atomic_read(&wait_req.done)) {
2187                         err = wait_req.err;
2188                         break;
2189                 }
2190                 if (!signal_pending(current)) {
2191                         schedule();
2192                         continue;
2193                 }
2194                 err = -ERESTARTSYS;
2195                 break;
2196         }
2197         finish_wait(&sci->sc_wait_request, &wait_req.wq);
2198         return err;
2199 }
2200 
2201 static void nilfs_segctor_wakeup(struct nilfs_sc_info *sci, int err)
2202 {
2203         struct nilfs_segctor_wait_request *wrq, *n;
2204         unsigned long flags;
2205 
2206         spin_lock_irqsave(&sci->sc_wait_request.lock, flags);
2207         list_for_each_entry_safe(wrq, n, &sci->sc_wait_request.head, wq.entry) {
2208                 if (!atomic_read(&wrq->done) &&
2209                     nilfs_cnt32_ge(sci->sc_seq_done, wrq->seq)) {
2210                         wrq->err = err;
2211                         atomic_set(&wrq->done, 1);
2212                 }
2213                 if (atomic_read(&wrq->done)) {
2214                         wrq->wq.func(&wrq->wq,
2215                                      TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
2216                                      0, NULL);
2217                 }
2218         }
2219         spin_unlock_irqrestore(&sci->sc_wait_request.lock, flags);
2220 }
2221 
2222 /**
2223  * nilfs_construct_segment - construct a logical segment
2224  * @sb: super block
2225  *
2226  * Return Value: On success, 0 is retured. On errors, one of the following
2227  * negative error code is returned.
2228  *
2229  * %-EROFS - Read only filesystem.
2230  *
2231  * %-EIO - I/O error
2232  *
2233  * %-ENOSPC - No space left on device (only in a panic state).
2234  *
2235  * %-ERESTARTSYS - Interrupted.
2236  *
2237  * %-ENOMEM - Insufficient memory available.
2238  */
2239 int nilfs_construct_segment(struct super_block *sb)
2240 {
2241         struct the_nilfs *nilfs = sb->s_fs_info;
2242         struct nilfs_sc_info *sci = nilfs->ns_writer;
2243         struct nilfs_transaction_info *ti;
2244         int err;
2245 
2246         if (!sci)
2247                 return -EROFS;
2248 
2249         /* A call inside transactions causes a deadlock. */
2250         BUG_ON((ti = current->journal_info) && ti->ti_magic == NILFS_TI_MAGIC);
2251 
2252         err = nilfs_segctor_sync(sci);
2253         return err;
2254 }
2255 
2256 /**
2257  * nilfs_construct_dsync_segment - construct a data-only logical segment
2258  * @sb: super block
2259  * @inode: inode whose data blocks should be written out
2260  * @start: start byte offset
2261  * @end: end byte offset (inclusive)
2262  *
2263  * Return Value: On success, 0 is retured. On errors, one of the following
2264  * negative error code is returned.
2265  *
2266  * %-EROFS - Read only filesystem.
2267  *
2268  * %-EIO - I/O error
2269  *
2270  * %-ENOSPC - No space left on device (only in a panic state).
2271  *
2272  * %-ERESTARTSYS - Interrupted.
2273  *
2274  * %-ENOMEM - Insufficient memory available.
2275  */
2276 int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
2277                                   loff_t start, loff_t end)
2278 {
2279         struct the_nilfs *nilfs = sb->s_fs_info;
2280         struct nilfs_sc_info *sci = nilfs->ns_writer;
2281         struct nilfs_inode_info *ii;
2282         struct nilfs_transaction_info ti;
2283         int err = 0;
2284 
2285         if (!sci)
2286                 return -EROFS;
2287 
2288         nilfs_transaction_lock(sb, &ti, 0);
2289 
2290         ii = NILFS_I(inode);
2291         if (test_bit(NILFS_I_INODE_SYNC, &ii->i_state) ||
2292             nilfs_test_opt(nilfs, STRICT_ORDER) ||
2293             test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2294             nilfs_discontinued(nilfs)) {
2295                 nilfs_transaction_unlock(sb);
2296                 err = nilfs_segctor_sync(sci);
2297                 return err;
2298         }
2299 
2300         spin_lock(&nilfs->ns_inode_lock);
2301         if (!test_bit(NILFS_I_QUEUED, &ii->i_state) &&
2302             !test_bit(NILFS_I_BUSY, &ii->i_state)) {
2303                 spin_unlock(&nilfs->ns_inode_lock);
2304                 nilfs_transaction_unlock(sb);
2305                 return 0;
2306         }
2307         spin_unlock(&nilfs->ns_inode_lock);
2308         sci->sc_dsync_inode = ii;
2309         sci->sc_dsync_start = start;
2310         sci->sc_dsync_end = end;
2311 
2312         err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);
2313         if (!err)
2314                 nilfs->ns_flushed_device = 0;
2315 
2316         nilfs_transaction_unlock(sb);
2317         return err;
2318 }
2319 
2320 #define FLUSH_FILE_BIT  (0x1) /* data file only */
2321 #define FLUSH_DAT_BIT   BIT(NILFS_DAT_INO) /* DAT only */
2322 
2323 /**
2324  * nilfs_segctor_accept - record accepted sequence count of log-write requests
2325  * @sci: segment constructor object
2326  */
2327 static void nilfs_segctor_accept(struct nilfs_sc_info *sci)
2328 {
2329         spin_lock(&sci->sc_state_lock);
2330         sci->sc_seq_accepted = sci->sc_seq_request;
2331         spin_unlock(&sci->sc_state_lock);
2332         del_timer_sync(&sci->sc_timer);
2333 }
2334 
2335 /**
2336  * nilfs_segctor_notify - notify the result of request to caller threads
2337  * @sci: segment constructor object
2338  * @mode: mode of log forming
2339  * @err: error code to be notified
2340  */
2341 static void nilfs_segctor_notify(struct nilfs_sc_info *sci, int mode, int err)
2342 {
2343         /* Clear requests (even when the construction failed) */
2344         spin_lock(&sci->sc_state_lock);
2345 
2346         if (mode == SC_LSEG_SR) {
2347                 sci->sc_state &= ~NILFS_SEGCTOR_COMMIT;
2348                 sci->sc_seq_done = sci->sc_seq_accepted;
2349                 nilfs_segctor_wakeup(sci, err);
2350                 sci->sc_flush_request = 0;
2351         } else {
2352                 if (mode == SC_FLUSH_FILE)
2353                         sci->sc_flush_request &= ~FLUSH_FILE_BIT;
2354                 else if (mode == SC_FLUSH_DAT)
2355                         sci->sc_flush_request &= ~FLUSH_DAT_BIT;
2356 
2357                 /* re-enable timer if checkpoint creation was not done */
2358                 if ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2359                     time_before(jiffies, sci->sc_timer.expires))
2360                         add_timer(&sci->sc_timer);
2361         }
2362         spin_unlock(&sci->sc_state_lock);
2363 }
2364 
2365 /**
2366  * nilfs_segctor_construct - form logs and write them to disk
2367  * @sci: segment constructor object
2368  * @mode: mode of log forming
2369  */
2370 static int nilfs_segctor_construct(struct nilfs_sc_info *sci, int mode)
2371 {
2372         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2373         struct nilfs_super_block **sbp;
2374         int err = 0;
2375 
2376         nilfs_segctor_accept(sci);
2377 
2378         if (nilfs_discontinued(nilfs))
2379                 mode = SC_LSEG_SR;
2380         if (!nilfs_segctor_confirm(sci))
2381                 err = nilfs_segctor_do_construct(sci, mode);
2382 
2383         if (likely(!err)) {
2384                 if (mode != SC_FLUSH_DAT)
2385                         atomic_set(&nilfs->ns_ndirtyblks, 0);
2386                 if (test_bit(NILFS_SC_SUPER_ROOT, &sci->sc_flags) &&
2387                     nilfs_discontinued(nilfs)) {
2388                         down_write(&nilfs->ns_sem);
2389                         err = -EIO;
2390                         sbp = nilfs_prepare_super(sci->sc_super,
2391                                                   nilfs_sb_will_flip(nilfs));
2392                         if (likely(sbp)) {
2393                                 nilfs_set_log_cursor(sbp[0], nilfs);
2394                                 err = nilfs_commit_super(sci->sc_super,
2395                                                          NILFS_SB_COMMIT);
2396                         }
2397                         up_write(&nilfs->ns_sem);
2398                 }
2399         }
2400 
2401         nilfs_segctor_notify(sci, mode, err);
2402         return err;
2403 }
2404 
2405 static void nilfs_construction_timeout(struct timer_list *t)
2406 {
2407         struct nilfs_sc_info *sci = from_timer(sci, t, sc_timer);
2408 
2409         wake_up_process(sci->sc_timer_task);
2410 }
2411 
2412 static void
2413 nilfs_remove_written_gcinodes(struct the_nilfs *nilfs, struct list_head *head)
2414 {
2415         struct nilfs_inode_info *ii, *n;
2416 
2417         list_for_each_entry_safe(ii, n, head, i_dirty) {
2418                 if (!test_bit(NILFS_I_UPDATED, &ii->i_state))
2419                         continue;
2420                 list_del_init(&ii->i_dirty);
2421                 truncate_inode_pages(&ii->vfs_inode.i_data, 0);
2422                 nilfs_btnode_cache_clear(&ii->i_btnode_cache);
2423                 iput(&ii->vfs_inode);
2424         }
2425 }
2426 
2427 int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
2428                          void **kbufs)
2429 {
2430         struct the_nilfs *nilfs = sb->s_fs_info;
2431         struct nilfs_sc_info *sci = nilfs->ns_writer;
2432         struct nilfs_transaction_info ti;
2433         int err;
2434 
2435         if (unlikely(!sci))
2436                 return -EROFS;
2437 
2438         nilfs_transaction_lock(sb, &ti, 1);
2439 
2440         err = nilfs_mdt_save_to_shadow_map(nilfs->ns_dat);
2441         if (unlikely(err))
2442                 goto out_unlock;
2443 
2444         err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
2445         if (unlikely(err)) {
2446                 nilfs_mdt_restore_from_shadow_map(nilfs->ns_dat);
2447                 goto out_unlock;
2448         }
2449 
2450         sci->sc_freesegs = kbufs[4];
2451         sci->sc_nfreesegs = argv[4].v_nmembs;
2452         list_splice_tail_init(&nilfs->ns_gc_inodes, &sci->sc_gc_inodes);
2453 
2454         for (;;) {
2455                 err = nilfs_segctor_construct(sci, SC_LSEG_SR);
2456                 nilfs_remove_written_gcinodes(nilfs, &sci->sc_gc_inodes);
2457 
2458                 if (likely(!err))
2459                         break;
2460 
2461                 nilfs_msg(sb, KERN_WARNING, "error %d cleaning segments", err);
2462                 set_current_state(TASK_INTERRUPTIBLE);
2463                 schedule_timeout(sci->sc_interval);
2464         }
2465         if (nilfs_test_opt(nilfs, DISCARD)) {
2466                 int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
2467                                                  sci->sc_nfreesegs);
2468                 if (ret) {
2469                         nilfs_msg(sb, KERN_WARNING,
2470                                   "error %d on discard request, turning discards off for the device",
2471                                   ret);
2472                         nilfs_clear_opt(nilfs, DISCARD);
2473                 }
2474         }
2475 
2476  out_unlock:
2477         sci->sc_freesegs = NULL;
2478         sci->sc_nfreesegs = 0;
2479         nilfs_mdt_clear_shadow_map(nilfs->ns_dat);
2480         nilfs_transaction_unlock(sb);
2481         return err;
2482 }
2483 
2484 static void nilfs_segctor_thread_construct(struct nilfs_sc_info *sci, int mode)
2485 {
2486         struct nilfs_transaction_info ti;
2487 
2488         nilfs_transaction_lock(sci->sc_super, &ti, 0);
2489         nilfs_segctor_construct(sci, mode);
2490 
2491         /*
2492          * Unclosed segment should be retried.  We do this using sc_timer.
2493          * Timeout of sc_timer will invoke complete construction which leads
2494          * to close the current logical segment.
2495          */
2496         if (test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags))
2497                 nilfs_segctor_start_timer(sci);
2498 
2499         nilfs_transaction_unlock(sci->sc_super);
2500 }
2501 
2502 static void nilfs_segctor_do_immediate_flush(struct nilfs_sc_info *sci)
2503 {
2504         int mode = 0;
2505 
2506         spin_lock(&sci->sc_state_lock);
2507         mode = (sci->sc_flush_request & FLUSH_DAT_BIT) ?
2508                 SC_FLUSH_DAT : SC_FLUSH_FILE;
2509         spin_unlock(&sci->sc_state_lock);
2510 
2511         if (mode) {
2512                 nilfs_segctor_do_construct(sci, mode);
2513 
2514                 spin_lock(&sci->sc_state_lock);
2515                 sci->sc_flush_request &= (mode == SC_FLUSH_FILE) ?
2516                         ~FLUSH_FILE_BIT : ~FLUSH_DAT_BIT;
2517                 spin_unlock(&sci->sc_state_lock);
2518         }
2519         clear_bit(NILFS_SC_PRIOR_FLUSH, &sci->sc_flags);
2520 }
2521 
2522 static int nilfs_segctor_flush_mode(struct nilfs_sc_info *sci)
2523 {
2524         if (!test_bit(NILFS_SC_UNCLOSED, &sci->sc_flags) ||
2525             time_before(jiffies, sci->sc_lseg_stime + sci->sc_mjcp_freq)) {
2526                 if (!(sci->sc_flush_request & ~FLUSH_FILE_BIT))
2527                         return SC_FLUSH_FILE;
2528                 else if (!(sci->sc_flush_request & ~FLUSH_DAT_BIT))
2529                         return SC_FLUSH_DAT;
2530         }
2531         return SC_LSEG_SR;
2532 }
2533 
2534 /**
2535  * nilfs_segctor_thread - main loop of the segment constructor thread.
2536  * @arg: pointer to a struct nilfs_sc_info.
2537  *
2538  * nilfs_segctor_thread() initializes a timer and serves as a daemon
2539  * to execute segment constructions.
2540  */
2541 static int nilfs_segctor_thread(void *arg)
2542 {
2543         struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
2544         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2545         int timeout = 0;
2546 
2547         sci->sc_timer_task = current;
2548 
2549         /* start sync. */
2550         sci->sc_task = current;
2551         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_start_thread() */
2552         nilfs_msg(sci->sc_super, KERN_INFO,
2553                   "segctord starting. Construction interval = %lu seconds, CP frequency < %lu seconds",
2554                   sci->sc_interval / HZ, sci->sc_mjcp_freq / HZ);
2555 
2556         spin_lock(&sci->sc_state_lock);
2557  loop:
2558         for (;;) {
2559                 int mode;
2560 
2561                 if (sci->sc_state & NILFS_SEGCTOR_QUIT)
2562                         goto end_thread;
2563 
2564                 if (timeout || sci->sc_seq_request != sci->sc_seq_done)
2565                         mode = SC_LSEG_SR;
2566                 else if (sci->sc_flush_request)
2567                         mode = nilfs_segctor_flush_mode(sci);
2568                 else
2569                         break;
2570 
2571                 spin_unlock(&sci->sc_state_lock);
2572                 nilfs_segctor_thread_construct(sci, mode);
2573                 spin_lock(&sci->sc_state_lock);
2574                 timeout = 0;
2575         }
2576 
2577 
2578         if (freezing(current)) {
2579                 spin_unlock(&sci->sc_state_lock);
2580                 try_to_freeze();
2581                 spin_lock(&sci->sc_state_lock);
2582         } else {
2583                 DEFINE_WAIT(wait);
2584                 int should_sleep = 1;
2585 
2586                 prepare_to_wait(&sci->sc_wait_daemon, &wait,
2587                                 TASK_INTERRUPTIBLE);
2588 
2589                 if (sci->sc_seq_request != sci->sc_seq_done)
2590                         should_sleep = 0;
2591                 else if (sci->sc_flush_request)
2592                         should_sleep = 0;
2593                 else if (sci->sc_state & NILFS_SEGCTOR_COMMIT)
2594                         should_sleep = time_before(jiffies,
2595                                         sci->sc_timer.expires);
2596 
2597                 if (should_sleep) {
2598                         spin_unlock(&sci->sc_state_lock);
2599                         schedule();
2600                         spin_lock(&sci->sc_state_lock);
2601                 }
2602                 finish_wait(&sci->sc_wait_daemon, &wait);
2603                 timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
2604                            time_after_eq(jiffies, sci->sc_timer.expires));
2605 
2606                 if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
2607                         set_nilfs_discontinued(nilfs);
2608         }
2609         goto loop;
2610 
2611  end_thread:
2612         spin_unlock(&sci->sc_state_lock);
2613 
2614         /* end sync. */
2615         sci->sc_task = NULL;
2616         wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */
2617         return 0;
2618 }
2619 
2620 static int nilfs_segctor_start_thread(struct nilfs_sc_info *sci)
2621 {
2622         struct task_struct *t;
2623 
2624         t = kthread_run(nilfs_segctor_thread, sci, "segctord");
2625         if (IS_ERR(t)) {
2626                 int err = PTR_ERR(t);
2627 
2628                 nilfs_msg(sci->sc_super, KERN_ERR,
2629                           "error %d creating segctord thread", err);
2630                 return err;
2631         }
2632         wait_event(sci->sc_wait_task, sci->sc_task != NULL);
2633         return 0;
2634 }
2635 
2636 static void nilfs_segctor_kill_thread(struct nilfs_sc_info *sci)
2637         __acquires(&sci->sc_state_lock)
2638         __releases(&sci->sc_state_lock)
2639 {
2640         sci->sc_state |= NILFS_SEGCTOR_QUIT;
2641 
2642         while (sci->sc_task) {
2643                 wake_up(&sci->sc_wait_daemon);
2644                 spin_unlock(&sci->sc_state_lock);
2645                 wait_event(sci->sc_wait_task, sci->sc_task == NULL);
2646                 spin_lock(&sci->sc_state_lock);
2647         }
2648 }
2649 
2650 /*
2651  * Setup & clean-up functions
2652  */
2653 static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
2654                                                struct nilfs_root *root)
2655 {
2656         struct the_nilfs *nilfs = sb->s_fs_info;
2657         struct nilfs_sc_info *sci;
2658 
2659         sci = kzalloc(sizeof(*sci), GFP_KERNEL);
2660         if (!sci)
2661                 return NULL;
2662 
2663         sci->sc_super = sb;
2664 
2665         nilfs_get_root(root);
2666         sci->sc_root = root;
2667 
2668         init_waitqueue_head(&sci->sc_wait_request);
2669         init_waitqueue_head(&sci->sc_wait_daemon);
2670         init_waitqueue_head(&sci->sc_wait_task);
2671         spin_lock_init(&sci->sc_state_lock);
2672         INIT_LIST_HEAD(&sci->sc_dirty_files);
2673         INIT_LIST_HEAD(&sci->sc_segbufs);
2674         INIT_LIST_HEAD(&sci->sc_write_logs);
2675         INIT_LIST_HEAD(&sci->sc_gc_inodes);
2676         INIT_LIST_HEAD(&sci->sc_iput_queue);
2677         INIT_WORK(&sci->sc_iput_work, nilfs_iput_work_func);
2678         timer_setup(&sci->sc_timer, nilfs_construction_timeout, 0);
2679 
2680         sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
2681         sci->sc_mjcp_freq = HZ * NILFS_SC_DEFAULT_SR_FREQ;
2682         sci->sc_watermark = NILFS_SC_DEFAULT_WATERMARK;
2683 
2684         if (nilfs->ns_interval)
2685                 sci->sc_interval = HZ * nilfs->ns_interval;
2686         if (nilfs->ns_watermark)
2687                 sci->sc_watermark = nilfs->ns_watermark;
2688         return sci;
2689 }
2690 
2691 static void nilfs_segctor_write_out(struct nilfs_sc_info *sci)
2692 {
2693         int ret, retrycount = NILFS_SC_CLEANUP_RETRY;
2694 
2695         /*
2696          * The segctord thread was stopped and its timer was removed.
2697          * But some tasks remain.
2698          */
2699         do {
2700                 struct nilfs_transaction_info ti;
2701 
2702                 nilfs_transaction_lock(sci->sc_super, &ti, 0);
2703                 ret = nilfs_segctor_construct(sci, SC_LSEG_SR);
2704                 nilfs_transaction_unlock(sci->sc_super);
2705 
2706                 flush_work(&sci->sc_iput_work);
2707 
2708         } while (ret && retrycount-- > 0);
2709 }
2710 
2711 /**
2712  * nilfs_segctor_destroy - destroy the segment constructor.
2713  * @sci: nilfs_sc_info
2714  *
2715  * nilfs_segctor_destroy() kills the segctord thread and frees
2716  * the nilfs_sc_info struct.
2717  * Caller must hold the segment semaphore.
2718  */
2719 static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
2720 {
2721         struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
2722         int flag;
2723 
2724         up_write(&nilfs->ns_segctor_sem);
2725 
2726         spin_lock(&sci->sc_state_lock);
2727         nilfs_segctor_kill_thread(sci);
2728         flag = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) || sci->sc_flush_request
2729                 || sci->sc_seq_request != sci->sc_seq_done);
2730         spin_unlock(&sci->sc_state_lock);
2731 
2732         if (flush_work(&sci->sc_iput_work))
2733                 flag = true;
2734 
2735         if (flag || !nilfs_segctor_confirm(sci))
2736                 nilfs_segctor_write_out(sci);
2737 
2738         if (!list_empty(&sci->sc_dirty_files)) {
2739                 nilfs_msg(sci->sc_super, KERN_WARNING,
2740                           "disposed unprocessed dirty file(s) when stopping log writer");
2741                 nilfs_dispose_list(nilfs, &sci->sc_dirty_files, 1);
2742         }
2743 
2744         if (!list_empty(&sci->sc_iput_queue)) {
2745                 nilfs_msg(sci->sc_super, KERN_WARNING,
2746                           "disposed unprocessed inode(s) in iput queue when stopping log writer");
2747                 nilfs_dispose_list(nilfs, &sci->sc_iput_queue, 1);
2748         }
2749 
2750         WARN_ON(!list_empty(&sci->sc_segbufs));
2751         WARN_ON(!list_empty(&sci->sc_write_logs));
2752 
2753         nilfs_put_root(sci->sc_root);
2754 
2755         down_write(&nilfs->ns_segctor_sem);
2756 
2757         del_timer_sync(&sci->sc_timer);
2758         kfree(sci);
2759 }
2760 
2761 /**
2762  * nilfs_attach_log_writer - attach log writer
2763  * @sb: super block instance
2764  * @root: root object of the current filesystem tree
2765  *
2766  * This allocates a log writer object, initializes it, and starts the
2767  * log writer.
2768  *
2769  * Return Value: On success, 0 is returned. On error, one of the following
2770  * negative error code is returned.
2771  *
2772  * %-ENOMEM - Insufficient memory available.
2773  */
2774 int nilfs_attach_log_writer(struct super_block *sb, struct nilfs_root *root)
2775 {
2776         struct the_nilfs *nilfs = sb->s_fs_info;
2777         int err;
2778 
2779         if (nilfs->ns_writer) {
2780                 /*
2781                  * This happens if the filesystem was remounted
2782                  * read/write after nilfs_error degenerated it into a
2783                  * read-only mount.
2784                  */
2785                 nilfs_detach_log_writer(sb);
2786         }
2787 
2788         nilfs->ns_writer = nilfs_segctor_new(sb, root);
2789         if (!nilfs->ns_writer)
2790                 return -ENOMEM;
2791 
2792         err = nilfs_segctor_start_thread(nilfs->ns_writer);
2793         if (err) {
2794                 kfree(nilfs->ns_writer);
2795                 nilfs->ns_writer = NULL;
2796         }
2797         return err;
2798 }
2799 
2800 /**
2801  * nilfs_detach_log_writer - destroy log writer
2802  * @sb: super block instance
2803  *
2804  * This kills log writer daemon, frees the log writer object, and
2805  * destroys list of dirty files.
2806  */
2807 void nilfs_detach_log_writer(struct super_block *sb)
2808 {
2809         struct the_nilfs *nilfs = sb->s_fs_info;
2810         LIST_HEAD(garbage_list);
2811 
2812         down_write(&nilfs->ns_segctor_sem);
2813         if (nilfs->ns_writer) {
2814                 nilfs_segctor_destroy(nilfs->ns_writer);
2815                 nilfs->ns_writer = NULL;
2816         }
2817 
2818         /* Force to free the list of dirty files */
2819         spin_lock(&nilfs->ns_inode_lock);
2820         if (!list_empty(&nilfs->ns_dirty_files)) {
2821                 list_splice_init(&nilfs->ns_dirty_files, &garbage_list);
2822                 nilfs_msg(sb, KERN_WARNING,
2823                           "disposed unprocessed dirty file(s) when detaching log writer");
2824         }
2825         spin_unlock(&nilfs->ns_inode_lock);
2826         up_write(&nilfs->ns_segctor_sem);
2827 
2828         nilfs_dispose_list(nilfs, &garbage_list, 1);
2829 }
2830 

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