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Linux/fs/xfs/xfs_icache.c

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  1 /*
  2  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
  3  * All Rights Reserved.
  4  *
  5  * This program is free software; you can redistribute it and/or
  6  * modify it under the terms of the GNU General Public License as
  7  * published by the Free Software Foundation.
  8  *
  9  * This program is distributed in the hope that it would be useful,
 10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12  * GNU General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, write the Free Software Foundation,
 16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 17  */
 18 #include "xfs.h"
 19 #include "xfs_fs.h"
 20 #include "xfs_format.h"
 21 #include "xfs_log_format.h"
 22 #include "xfs_trans_resv.h"
 23 #include "xfs_sb.h"
 24 #include "xfs_mount.h"
 25 #include "xfs_inode.h"
 26 #include "xfs_error.h"
 27 #include "xfs_trans.h"
 28 #include "xfs_trans_priv.h"
 29 #include "xfs_inode_item.h"
 30 #include "xfs_quota.h"
 31 #include "xfs_trace.h"
 32 #include "xfs_icache.h"
 33 #include "xfs_bmap_util.h"
 34 #include "xfs_dquot_item.h"
 35 #include "xfs_dquot.h"
 36 
 37 #include <linux/kthread.h>
 38 #include <linux/freezer.h>
 39 
 40 /*
 41  * Allocate and initialise an xfs_inode.
 42  */
 43 struct xfs_inode *
 44 xfs_inode_alloc(
 45         struct xfs_mount        *mp,
 46         xfs_ino_t               ino)
 47 {
 48         struct xfs_inode        *ip;
 49 
 50         /*
 51          * if this didn't occur in transactions, we could use
 52          * KM_MAYFAIL and return NULL here on ENOMEM. Set the
 53          * code up to do this anyway.
 54          */
 55         ip = kmem_zone_alloc(xfs_inode_zone, KM_SLEEP);
 56         if (!ip)
 57                 return NULL;
 58         if (inode_init_always(mp->m_super, VFS_I(ip))) {
 59                 kmem_zone_free(xfs_inode_zone, ip);
 60                 return NULL;
 61         }
 62 
 63         /* VFS doesn't initialise i_mode! */
 64         VFS_I(ip)->i_mode = 0;
 65 
 66         XFS_STATS_INC(mp, vn_active);
 67         ASSERT(atomic_read(&ip->i_pincount) == 0);
 68         ASSERT(!spin_is_locked(&ip->i_flags_lock));
 69         ASSERT(!xfs_isiflocked(ip));
 70         ASSERT(ip->i_ino == 0);
 71 
 72         mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
 73 
 74         /* initialise the xfs inode */
 75         ip->i_ino = ino;
 76         ip->i_mount = mp;
 77         memset(&ip->i_imap, 0, sizeof(struct xfs_imap));
 78         ip->i_afp = NULL;
 79         memset(&ip->i_df, 0, sizeof(xfs_ifork_t));
 80         ip->i_flags = 0;
 81         ip->i_delayed_blks = 0;
 82         memset(&ip->i_d, 0, sizeof(ip->i_d));
 83 
 84         return ip;
 85 }
 86 
 87 STATIC void
 88 xfs_inode_free_callback(
 89         struct rcu_head         *head)
 90 {
 91         struct inode            *inode = container_of(head, struct inode, i_rcu);
 92         struct xfs_inode        *ip = XFS_I(inode);
 93 
 94         switch (VFS_I(ip)->i_mode & S_IFMT) {
 95         case S_IFREG:
 96         case S_IFDIR:
 97         case S_IFLNK:
 98                 xfs_idestroy_fork(ip, XFS_DATA_FORK);
 99                 break;
100         }
101 
102         if (ip->i_afp)
103                 xfs_idestroy_fork(ip, XFS_ATTR_FORK);
104 
105         if (ip->i_itemp) {
106                 ASSERT(!(ip->i_itemp->ili_item.li_flags & XFS_LI_IN_AIL));
107                 xfs_inode_item_destroy(ip);
108                 ip->i_itemp = NULL;
109         }
110 
111         kmem_zone_free(xfs_inode_zone, ip);
112 }
113 
114 static void
115 __xfs_inode_free(
116         struct xfs_inode        *ip)
117 {
118         /* asserts to verify all state is correct here */
119         ASSERT(atomic_read(&ip->i_pincount) == 0);
120         ASSERT(!xfs_isiflocked(ip));
121         XFS_STATS_DEC(ip->i_mount, vn_active);
122 
123         call_rcu(&VFS_I(ip)->i_rcu, xfs_inode_free_callback);
124 }
125 
126 void
127 xfs_inode_free(
128         struct xfs_inode        *ip)
129 {
130         /*
131          * Because we use RCU freeing we need to ensure the inode always
132          * appears to be reclaimed with an invalid inode number when in the
133          * free state. The ip->i_flags_lock provides the barrier against lookup
134          * races.
135          */
136         spin_lock(&ip->i_flags_lock);
137         ip->i_flags = XFS_IRECLAIM;
138         ip->i_ino = 0;
139         spin_unlock(&ip->i_flags_lock);
140 
141         __xfs_inode_free(ip);
142 }
143 
144 /*
145  * Queue a new inode reclaim pass if there are reclaimable inodes and there
146  * isn't a reclaim pass already in progress. By default it runs every 5s based
147  * on the xfs periodic sync default of 30s. Perhaps this should have it's own
148  * tunable, but that can be done if this method proves to be ineffective or too
149  * aggressive.
150  */
151 static void
152 xfs_reclaim_work_queue(
153         struct xfs_mount        *mp)
154 {
155 
156         rcu_read_lock();
157         if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
158                 queue_delayed_work(mp->m_reclaim_workqueue, &mp->m_reclaim_work,
159                         msecs_to_jiffies(xfs_syncd_centisecs / 6 * 10));
160         }
161         rcu_read_unlock();
162 }
163 
164 /*
165  * This is a fast pass over the inode cache to try to get reclaim moving on as
166  * many inodes as possible in a short period of time. It kicks itself every few
167  * seconds, as well as being kicked by the inode cache shrinker when memory
168  * goes low. It scans as quickly as possible avoiding locked inodes or those
169  * already being flushed, and once done schedules a future pass.
170  */
171 void
172 xfs_reclaim_worker(
173         struct work_struct *work)
174 {
175         struct xfs_mount *mp = container_of(to_delayed_work(work),
176                                         struct xfs_mount, m_reclaim_work);
177 
178         xfs_reclaim_inodes(mp, SYNC_TRYLOCK);
179         xfs_reclaim_work_queue(mp);
180 }
181 
182 static void
183 xfs_perag_set_reclaim_tag(
184         struct xfs_perag        *pag)
185 {
186         struct xfs_mount        *mp = pag->pag_mount;
187 
188         ASSERT(spin_is_locked(&pag->pag_ici_lock));
189         if (pag->pag_ici_reclaimable++)
190                 return;
191 
192         /* propagate the reclaim tag up into the perag radix tree */
193         spin_lock(&mp->m_perag_lock);
194         radix_tree_tag_set(&mp->m_perag_tree, pag->pag_agno,
195                            XFS_ICI_RECLAIM_TAG);
196         spin_unlock(&mp->m_perag_lock);
197 
198         /* schedule periodic background inode reclaim */
199         xfs_reclaim_work_queue(mp);
200 
201         trace_xfs_perag_set_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
202 }
203 
204 static void
205 xfs_perag_clear_reclaim_tag(
206         struct xfs_perag        *pag)
207 {
208         struct xfs_mount        *mp = pag->pag_mount;
209 
210         ASSERT(spin_is_locked(&pag->pag_ici_lock));
211         if (--pag->pag_ici_reclaimable)
212                 return;
213 
214         /* clear the reclaim tag from the perag radix tree */
215         spin_lock(&mp->m_perag_lock);
216         radix_tree_tag_clear(&mp->m_perag_tree, pag->pag_agno,
217                              XFS_ICI_RECLAIM_TAG);
218         spin_unlock(&mp->m_perag_lock);
219         trace_xfs_perag_clear_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
220 }
221 
222 
223 /*
224  * We set the inode flag atomically with the radix tree tag.
225  * Once we get tag lookups on the radix tree, this inode flag
226  * can go away.
227  */
228 void
229 xfs_inode_set_reclaim_tag(
230         struct xfs_inode        *ip)
231 {
232         struct xfs_mount        *mp = ip->i_mount;
233         struct xfs_perag        *pag;
234 
235         pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
236         spin_lock(&pag->pag_ici_lock);
237         spin_lock(&ip->i_flags_lock);
238 
239         radix_tree_tag_set(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, ip->i_ino),
240                            XFS_ICI_RECLAIM_TAG);
241         xfs_perag_set_reclaim_tag(pag);
242         __xfs_iflags_set(ip, XFS_IRECLAIMABLE);
243 
244         spin_unlock(&ip->i_flags_lock);
245         spin_unlock(&pag->pag_ici_lock);
246         xfs_perag_put(pag);
247 }
248 
249 STATIC void
250 xfs_inode_clear_reclaim_tag(
251         struct xfs_perag        *pag,
252         xfs_ino_t               ino)
253 {
254         radix_tree_tag_clear(&pag->pag_ici_root,
255                              XFS_INO_TO_AGINO(pag->pag_mount, ino),
256                              XFS_ICI_RECLAIM_TAG);
257         xfs_perag_clear_reclaim_tag(pag);
258 }
259 
260 /*
261  * When we recycle a reclaimable inode, we need to re-initialise the VFS inode
262  * part of the structure. This is made more complex by the fact we store
263  * information about the on-disk values in the VFS inode and so we can't just
264  * overwrite the values unconditionally. Hence we save the parameters we
265  * need to retain across reinitialisation, and rewrite them into the VFS inode
266  * after reinitialisation even if it fails.
267  */
268 static int
269 xfs_reinit_inode(
270         struct xfs_mount        *mp,
271         struct inode            *inode)
272 {
273         int             error;
274         uint32_t        nlink = inode->i_nlink;
275         uint32_t        generation = inode->i_generation;
276         uint64_t        version = inode->i_version;
277         umode_t         mode = inode->i_mode;
278 
279         error = inode_init_always(mp->m_super, inode);
280 
281         set_nlink(inode, nlink);
282         inode->i_generation = generation;
283         inode->i_version = version;
284         inode->i_mode = mode;
285         return error;
286 }
287 
288 /*
289  * Check the validity of the inode we just found it the cache
290  */
291 static int
292 xfs_iget_cache_hit(
293         struct xfs_perag        *pag,
294         struct xfs_inode        *ip,
295         xfs_ino_t               ino,
296         int                     flags,
297         int                     lock_flags) __releases(RCU)
298 {
299         struct inode            *inode = VFS_I(ip);
300         struct xfs_mount        *mp = ip->i_mount;
301         int                     error;
302 
303         /*
304          * check for re-use of an inode within an RCU grace period due to the
305          * radix tree nodes not being updated yet. We monitor for this by
306          * setting the inode number to zero before freeing the inode structure.
307          * If the inode has been reallocated and set up, then the inode number
308          * will not match, so check for that, too.
309          */
310         spin_lock(&ip->i_flags_lock);
311         if (ip->i_ino != ino) {
312                 trace_xfs_iget_skip(ip);
313                 XFS_STATS_INC(mp, xs_ig_frecycle);
314                 error = -EAGAIN;
315                 goto out_error;
316         }
317 
318 
319         /*
320          * If we are racing with another cache hit that is currently
321          * instantiating this inode or currently recycling it out of
322          * reclaimabe state, wait for the initialisation to complete
323          * before continuing.
324          *
325          * XXX(hch): eventually we should do something equivalent to
326          *           wait_on_inode to wait for these flags to be cleared
327          *           instead of polling for it.
328          */
329         if (ip->i_flags & (XFS_INEW|XFS_IRECLAIM)) {
330                 trace_xfs_iget_skip(ip);
331                 XFS_STATS_INC(mp, xs_ig_frecycle);
332                 error = -EAGAIN;
333                 goto out_error;
334         }
335 
336         /*
337          * If lookup is racing with unlink return an error immediately.
338          */
339         if (VFS_I(ip)->i_mode == 0 && !(flags & XFS_IGET_CREATE)) {
340                 error = -ENOENT;
341                 goto out_error;
342         }
343 
344         /*
345          * If IRECLAIMABLE is set, we've torn down the VFS inode already.
346          * Need to carefully get it back into useable state.
347          */
348         if (ip->i_flags & XFS_IRECLAIMABLE) {
349                 trace_xfs_iget_reclaim(ip);
350 
351                 /*
352                  * We need to set XFS_IRECLAIM to prevent xfs_reclaim_inode
353                  * from stomping over us while we recycle the inode.  We can't
354                  * clear the radix tree reclaimable tag yet as it requires
355                  * pag_ici_lock to be held exclusive.
356                  */
357                 ip->i_flags |= XFS_IRECLAIM;
358 
359                 spin_unlock(&ip->i_flags_lock);
360                 rcu_read_unlock();
361 
362                 error = xfs_reinit_inode(mp, inode);
363                 if (error) {
364                         /*
365                          * Re-initializing the inode failed, and we are in deep
366                          * trouble.  Try to re-add it to the reclaim list.
367                          */
368                         rcu_read_lock();
369                         spin_lock(&ip->i_flags_lock);
370 
371                         ip->i_flags &= ~(XFS_INEW | XFS_IRECLAIM);
372                         ASSERT(ip->i_flags & XFS_IRECLAIMABLE);
373                         trace_xfs_iget_reclaim_fail(ip);
374                         goto out_error;
375                 }
376 
377                 spin_lock(&pag->pag_ici_lock);
378                 spin_lock(&ip->i_flags_lock);
379 
380                 /*
381                  * Clear the per-lifetime state in the inode as we are now
382                  * effectively a new inode and need to return to the initial
383                  * state before reuse occurs.
384                  */
385                 ip->i_flags &= ~XFS_IRECLAIM_RESET_FLAGS;
386                 ip->i_flags |= XFS_INEW;
387                 xfs_inode_clear_reclaim_tag(pag, ip->i_ino);
388                 inode->i_state = I_NEW;
389 
390                 ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
391                 mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
392 
393                 spin_unlock(&ip->i_flags_lock);
394                 spin_unlock(&pag->pag_ici_lock);
395         } else {
396                 /* If the VFS inode is being torn down, pause and try again. */
397                 if (!igrab(inode)) {
398                         trace_xfs_iget_skip(ip);
399                         error = -EAGAIN;
400                         goto out_error;
401                 }
402 
403                 /* We've got a live one. */
404                 spin_unlock(&ip->i_flags_lock);
405                 rcu_read_unlock();
406                 trace_xfs_iget_hit(ip);
407         }
408 
409         if (lock_flags != 0)
410                 xfs_ilock(ip, lock_flags);
411 
412         xfs_iflags_clear(ip, XFS_ISTALE | XFS_IDONTCACHE);
413         XFS_STATS_INC(mp, xs_ig_found);
414 
415         return 0;
416 
417 out_error:
418         spin_unlock(&ip->i_flags_lock);
419         rcu_read_unlock();
420         return error;
421 }
422 
423 
424 static int
425 xfs_iget_cache_miss(
426         struct xfs_mount        *mp,
427         struct xfs_perag        *pag,
428         xfs_trans_t             *tp,
429         xfs_ino_t               ino,
430         struct xfs_inode        **ipp,
431         int                     flags,
432         int                     lock_flags)
433 {
434         struct xfs_inode        *ip;
435         int                     error;
436         xfs_agino_t             agino = XFS_INO_TO_AGINO(mp, ino);
437         int                     iflags;
438 
439         ip = xfs_inode_alloc(mp, ino);
440         if (!ip)
441                 return -ENOMEM;
442 
443         error = xfs_iread(mp, tp, ip, flags);
444         if (error)
445                 goto out_destroy;
446 
447         trace_xfs_iget_miss(ip);
448 
449         if ((VFS_I(ip)->i_mode == 0) && !(flags & XFS_IGET_CREATE)) {
450                 error = -ENOENT;
451                 goto out_destroy;
452         }
453 
454         /*
455          * Preload the radix tree so we can insert safely under the
456          * write spinlock. Note that we cannot sleep inside the preload
457          * region. Since we can be called from transaction context, don't
458          * recurse into the file system.
459          */
460         if (radix_tree_preload(GFP_NOFS)) {
461                 error = -EAGAIN;
462                 goto out_destroy;
463         }
464 
465         /*
466          * Because the inode hasn't been added to the radix-tree yet it can't
467          * be found by another thread, so we can do the non-sleeping lock here.
468          */
469         if (lock_flags) {
470                 if (!xfs_ilock_nowait(ip, lock_flags))
471                         BUG();
472         }
473 
474         /*
475          * These values must be set before inserting the inode into the radix
476          * tree as the moment it is inserted a concurrent lookup (allowed by the
477          * RCU locking mechanism) can find it and that lookup must see that this
478          * is an inode currently under construction (i.e. that XFS_INEW is set).
479          * The ip->i_flags_lock that protects the XFS_INEW flag forms the
480          * memory barrier that ensures this detection works correctly at lookup
481          * time.
482          */
483         iflags = XFS_INEW;
484         if (flags & XFS_IGET_DONTCACHE)
485                 iflags |= XFS_IDONTCACHE;
486         ip->i_udquot = NULL;
487         ip->i_gdquot = NULL;
488         ip->i_pdquot = NULL;
489         xfs_iflags_set(ip, iflags);
490 
491         /* insert the new inode */
492         spin_lock(&pag->pag_ici_lock);
493         error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
494         if (unlikely(error)) {
495                 WARN_ON(error != -EEXIST);
496                 XFS_STATS_INC(mp, xs_ig_dup);
497                 error = -EAGAIN;
498                 goto out_preload_end;
499         }
500         spin_unlock(&pag->pag_ici_lock);
501         radix_tree_preload_end();
502 
503         *ipp = ip;
504         return 0;
505 
506 out_preload_end:
507         spin_unlock(&pag->pag_ici_lock);
508         radix_tree_preload_end();
509         if (lock_flags)
510                 xfs_iunlock(ip, lock_flags);
511 out_destroy:
512         __destroy_inode(VFS_I(ip));
513         xfs_inode_free(ip);
514         return error;
515 }
516 
517 /*
518  * Look up an inode by number in the given file system.
519  * The inode is looked up in the cache held in each AG.
520  * If the inode is found in the cache, initialise the vfs inode
521  * if necessary.
522  *
523  * If it is not in core, read it in from the file system's device,
524  * add it to the cache and initialise the vfs inode.
525  *
526  * The inode is locked according to the value of the lock_flags parameter.
527  * This flag parameter indicates how and if the inode's IO lock and inode lock
528  * should be taken.
529  *
530  * mp -- the mount point structure for the current file system.  It points
531  *       to the inode hash table.
532  * tp -- a pointer to the current transaction if there is one.  This is
533  *       simply passed through to the xfs_iread() call.
534  * ino -- the number of the inode desired.  This is the unique identifier
535  *        within the file system for the inode being requested.
536  * lock_flags -- flags indicating how to lock the inode.  See the comment
537  *               for xfs_ilock() for a list of valid values.
538  */
539 int
540 xfs_iget(
541         xfs_mount_t     *mp,
542         xfs_trans_t     *tp,
543         xfs_ino_t       ino,
544         uint            flags,
545         uint            lock_flags,
546         xfs_inode_t     **ipp)
547 {
548         xfs_inode_t     *ip;
549         int             error;
550         xfs_perag_t     *pag;
551         xfs_agino_t     agino;
552 
553         /*
554          * xfs_reclaim_inode() uses the ILOCK to ensure an inode
555          * doesn't get freed while it's being referenced during a
556          * radix tree traversal here.  It assumes this function
557          * aqcuires only the ILOCK (and therefore it has no need to
558          * involve the IOLOCK in this synchronization).
559          */
560         ASSERT((lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) == 0);
561 
562         /* reject inode numbers outside existing AGs */
563         if (!ino || XFS_INO_TO_AGNO(mp, ino) >= mp->m_sb.sb_agcount)
564                 return -EINVAL;
565 
566         XFS_STATS_INC(mp, xs_ig_attempts);
567 
568         /* get the perag structure and ensure that it's inode capable */
569         pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
570         agino = XFS_INO_TO_AGINO(mp, ino);
571 
572 again:
573         error = 0;
574         rcu_read_lock();
575         ip = radix_tree_lookup(&pag->pag_ici_root, agino);
576 
577         if (ip) {
578                 error = xfs_iget_cache_hit(pag, ip, ino, flags, lock_flags);
579                 if (error)
580                         goto out_error_or_again;
581         } else {
582                 rcu_read_unlock();
583                 XFS_STATS_INC(mp, xs_ig_missed);
584 
585                 error = xfs_iget_cache_miss(mp, pag, tp, ino, &ip,
586                                                         flags, lock_flags);
587                 if (error)
588                         goto out_error_or_again;
589         }
590         xfs_perag_put(pag);
591 
592         *ipp = ip;
593 
594         /*
595          * If we have a real type for an on-disk inode, we can setup the inode
596          * now.  If it's a new inode being created, xfs_ialloc will handle it.
597          */
598         if (xfs_iflags_test(ip, XFS_INEW) && VFS_I(ip)->i_mode != 0)
599                 xfs_setup_existing_inode(ip);
600         return 0;
601 
602 out_error_or_again:
603         if (error == -EAGAIN) {
604                 delay(1);
605                 goto again;
606         }
607         xfs_perag_put(pag);
608         return error;
609 }
610 
611 /*
612  * The inode lookup is done in batches to keep the amount of lock traffic and
613  * radix tree lookups to a minimum. The batch size is a trade off between
614  * lookup reduction and stack usage. This is in the reclaim path, so we can't
615  * be too greedy.
616  */
617 #define XFS_LOOKUP_BATCH        32
618 
619 STATIC int
620 xfs_inode_ag_walk_grab(
621         struct xfs_inode        *ip)
622 {
623         struct inode            *inode = VFS_I(ip);
624 
625         ASSERT(rcu_read_lock_held());
626 
627         /*
628          * check for stale RCU freed inode
629          *
630          * If the inode has been reallocated, it doesn't matter if it's not in
631          * the AG we are walking - we are walking for writeback, so if it
632          * passes all the "valid inode" checks and is dirty, then we'll write
633          * it back anyway.  If it has been reallocated and still being
634          * initialised, the XFS_INEW check below will catch it.
635          */
636         spin_lock(&ip->i_flags_lock);
637         if (!ip->i_ino)
638                 goto out_unlock_noent;
639 
640         /* avoid new or reclaimable inodes. Leave for reclaim code to flush */
641         if (__xfs_iflags_test(ip, XFS_INEW | XFS_IRECLAIMABLE | XFS_IRECLAIM))
642                 goto out_unlock_noent;
643         spin_unlock(&ip->i_flags_lock);
644 
645         /* nothing to sync during shutdown */
646         if (XFS_FORCED_SHUTDOWN(ip->i_mount))
647                 return -EFSCORRUPTED;
648 
649         /* If we can't grab the inode, it must on it's way to reclaim. */
650         if (!igrab(inode))
651                 return -ENOENT;
652 
653         /* inode is valid */
654         return 0;
655 
656 out_unlock_noent:
657         spin_unlock(&ip->i_flags_lock);
658         return -ENOENT;
659 }
660 
661 STATIC int
662 xfs_inode_ag_walk(
663         struct xfs_mount        *mp,
664         struct xfs_perag        *pag,
665         int                     (*execute)(struct xfs_inode *ip, int flags,
666                                            void *args),
667         int                     flags,
668         void                    *args,
669         int                     tag)
670 {
671         uint32_t                first_index;
672         int                     last_error = 0;
673         int                     skipped;
674         int                     done;
675         int                     nr_found;
676 
677 restart:
678         done = 0;
679         skipped = 0;
680         first_index = 0;
681         nr_found = 0;
682         do {
683                 struct xfs_inode *batch[XFS_LOOKUP_BATCH];
684                 int             error = 0;
685                 int             i;
686 
687                 rcu_read_lock();
688 
689                 if (tag == -1)
690                         nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
691                                         (void **)batch, first_index,
692                                         XFS_LOOKUP_BATCH);
693                 else
694                         nr_found = radix_tree_gang_lookup_tag(
695                                         &pag->pag_ici_root,
696                                         (void **) batch, first_index,
697                                         XFS_LOOKUP_BATCH, tag);
698 
699                 if (!nr_found) {
700                         rcu_read_unlock();
701                         break;
702                 }
703 
704                 /*
705                  * Grab the inodes before we drop the lock. if we found
706                  * nothing, nr == 0 and the loop will be skipped.
707                  */
708                 for (i = 0; i < nr_found; i++) {
709                         struct xfs_inode *ip = batch[i];
710 
711                         if (done || xfs_inode_ag_walk_grab(ip))
712                                 batch[i] = NULL;
713 
714                         /*
715                          * Update the index for the next lookup. Catch
716                          * overflows into the next AG range which can occur if
717                          * we have inodes in the last block of the AG and we
718                          * are currently pointing to the last inode.
719                          *
720                          * Because we may see inodes that are from the wrong AG
721                          * due to RCU freeing and reallocation, only update the
722                          * index if it lies in this AG. It was a race that lead
723                          * us to see this inode, so another lookup from the
724                          * same index will not find it again.
725                          */
726                         if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag->pag_agno)
727                                 continue;
728                         first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
729                         if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
730                                 done = 1;
731                 }
732 
733                 /* unlock now we've grabbed the inodes. */
734                 rcu_read_unlock();
735 
736                 for (i = 0; i < nr_found; i++) {
737                         if (!batch[i])
738                                 continue;
739                         error = execute(batch[i], flags, args);
740                         IRELE(batch[i]);
741                         if (error == -EAGAIN) {
742                                 skipped++;
743                                 continue;
744                         }
745                         if (error && last_error != -EFSCORRUPTED)
746                                 last_error = error;
747                 }
748 
749                 /* bail out if the filesystem is corrupted.  */
750                 if (error == -EFSCORRUPTED)
751                         break;
752 
753                 cond_resched();
754 
755         } while (nr_found && !done);
756 
757         if (skipped) {
758                 delay(1);
759                 goto restart;
760         }
761         return last_error;
762 }
763 
764 /*
765  * Background scanning to trim post-EOF preallocated space. This is queued
766  * based on the 'speculative_prealloc_lifetime' tunable (5m by default).
767  */
768 void
769 xfs_queue_eofblocks(
770         struct xfs_mount *mp)
771 {
772         rcu_read_lock();
773         if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_EOFBLOCKS_TAG))
774                 queue_delayed_work(mp->m_eofblocks_workqueue,
775                                    &mp->m_eofblocks_work,
776                                    msecs_to_jiffies(xfs_eofb_secs * 1000));
777         rcu_read_unlock();
778 }
779 
780 void
781 xfs_eofblocks_worker(
782         struct work_struct *work)
783 {
784         struct xfs_mount *mp = container_of(to_delayed_work(work),
785                                 struct xfs_mount, m_eofblocks_work);
786         xfs_icache_free_eofblocks(mp, NULL);
787         xfs_queue_eofblocks(mp);
788 }
789 
790 int
791 xfs_inode_ag_iterator(
792         struct xfs_mount        *mp,
793         int                     (*execute)(struct xfs_inode *ip, int flags,
794                                            void *args),
795         int                     flags,
796         void                    *args)
797 {
798         struct xfs_perag        *pag;
799         int                     error = 0;
800         int                     last_error = 0;
801         xfs_agnumber_t          ag;
802 
803         ag = 0;
804         while ((pag = xfs_perag_get(mp, ag))) {
805                 ag = pag->pag_agno + 1;
806                 error = xfs_inode_ag_walk(mp, pag, execute, flags, args, -1);
807                 xfs_perag_put(pag);
808                 if (error) {
809                         last_error = error;
810                         if (error == -EFSCORRUPTED)
811                                 break;
812                 }
813         }
814         return last_error;
815 }
816 
817 int
818 xfs_inode_ag_iterator_tag(
819         struct xfs_mount        *mp,
820         int                     (*execute)(struct xfs_inode *ip, int flags,
821                                            void *args),
822         int                     flags,
823         void                    *args,
824         int                     tag)
825 {
826         struct xfs_perag        *pag;
827         int                     error = 0;
828         int                     last_error = 0;
829         xfs_agnumber_t          ag;
830 
831         ag = 0;
832         while ((pag = xfs_perag_get_tag(mp, ag, tag))) {
833                 ag = pag->pag_agno + 1;
834                 error = xfs_inode_ag_walk(mp, pag, execute, flags, args, tag);
835                 xfs_perag_put(pag);
836                 if (error) {
837                         last_error = error;
838                         if (error == -EFSCORRUPTED)
839                                 break;
840                 }
841         }
842         return last_error;
843 }
844 
845 /*
846  * Grab the inode for reclaim exclusively.
847  * Return 0 if we grabbed it, non-zero otherwise.
848  */
849 STATIC int
850 xfs_reclaim_inode_grab(
851         struct xfs_inode        *ip,
852         int                     flags)
853 {
854         ASSERT(rcu_read_lock_held());
855 
856         /* quick check for stale RCU freed inode */
857         if (!ip->i_ino)
858                 return 1;
859 
860         /*
861          * If we are asked for non-blocking operation, do unlocked checks to
862          * see if the inode already is being flushed or in reclaim to avoid
863          * lock traffic.
864          */
865         if ((flags & SYNC_TRYLOCK) &&
866             __xfs_iflags_test(ip, XFS_IFLOCK | XFS_IRECLAIM))
867                 return 1;
868 
869         /*
870          * The radix tree lock here protects a thread in xfs_iget from racing
871          * with us starting reclaim on the inode.  Once we have the
872          * XFS_IRECLAIM flag set it will not touch us.
873          *
874          * Due to RCU lookup, we may find inodes that have been freed and only
875          * have XFS_IRECLAIM set.  Indeed, we may see reallocated inodes that
876          * aren't candidates for reclaim at all, so we must check the
877          * XFS_IRECLAIMABLE is set first before proceeding to reclaim.
878          */
879         spin_lock(&ip->i_flags_lock);
880         if (!__xfs_iflags_test(ip, XFS_IRECLAIMABLE) ||
881             __xfs_iflags_test(ip, XFS_IRECLAIM)) {
882                 /* not a reclaim candidate. */
883                 spin_unlock(&ip->i_flags_lock);
884                 return 1;
885         }
886         __xfs_iflags_set(ip, XFS_IRECLAIM);
887         spin_unlock(&ip->i_flags_lock);
888         return 0;
889 }
890 
891 /*
892  * Inodes in different states need to be treated differently. The following
893  * table lists the inode states and the reclaim actions necessary:
894  *
895  *      inode state          iflush ret         required action
896  *      ---------------      ----------         ---------------
897  *      bad                     -               reclaim
898  *      shutdown                EIO             unpin and reclaim
899  *      clean, unpinned         0               reclaim
900  *      stale, unpinned         0               reclaim
901  *      clean, pinned(*)        0               requeue
902  *      stale, pinned           EAGAIN          requeue
903  *      dirty, async            -               requeue
904  *      dirty, sync             0               reclaim
905  *
906  * (*) dgc: I don't think the clean, pinned state is possible but it gets
907  * handled anyway given the order of checks implemented.
908  *
909  * Also, because we get the flush lock first, we know that any inode that has
910  * been flushed delwri has had the flush completed by the time we check that
911  * the inode is clean.
912  *
913  * Note that because the inode is flushed delayed write by AIL pushing, the
914  * flush lock may already be held here and waiting on it can result in very
915  * long latencies.  Hence for sync reclaims, where we wait on the flush lock,
916  * the caller should push the AIL first before trying to reclaim inodes to
917  * minimise the amount of time spent waiting.  For background relaim, we only
918  * bother to reclaim clean inodes anyway.
919  *
920  * Hence the order of actions after gaining the locks should be:
921  *      bad             => reclaim
922  *      shutdown        => unpin and reclaim
923  *      pinned, async   => requeue
924  *      pinned, sync    => unpin
925  *      stale           => reclaim
926  *      clean           => reclaim
927  *      dirty, async    => requeue
928  *      dirty, sync     => flush, wait and reclaim
929  */
930 STATIC int
931 xfs_reclaim_inode(
932         struct xfs_inode        *ip,
933         struct xfs_perag        *pag,
934         int                     sync_mode)
935 {
936         struct xfs_buf          *bp = NULL;
937         xfs_ino_t               ino = ip->i_ino; /* for radix_tree_delete */
938         int                     error;
939 
940 restart:
941         error = 0;
942         xfs_ilock(ip, XFS_ILOCK_EXCL);
943         if (!xfs_iflock_nowait(ip)) {
944                 if (!(sync_mode & SYNC_WAIT))
945                         goto out;
946                 xfs_iflock(ip);
947         }
948 
949         if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
950                 xfs_iunpin_wait(ip);
951                 xfs_iflush_abort(ip, false);
952                 goto reclaim;
953         }
954         if (xfs_ipincount(ip)) {
955                 if (!(sync_mode & SYNC_WAIT))
956                         goto out_ifunlock;
957                 xfs_iunpin_wait(ip);
958         }
959         if (xfs_iflags_test(ip, XFS_ISTALE))
960                 goto reclaim;
961         if (xfs_inode_clean(ip))
962                 goto reclaim;
963 
964         /*
965          * Never flush out dirty data during non-blocking reclaim, as it would
966          * just contend with AIL pushing trying to do the same job.
967          */
968         if (!(sync_mode & SYNC_WAIT))
969                 goto out_ifunlock;
970 
971         /*
972          * Now we have an inode that needs flushing.
973          *
974          * Note that xfs_iflush will never block on the inode buffer lock, as
975          * xfs_ifree_cluster() can lock the inode buffer before it locks the
976          * ip->i_lock, and we are doing the exact opposite here.  As a result,
977          * doing a blocking xfs_imap_to_bp() to get the cluster buffer would
978          * result in an ABBA deadlock with xfs_ifree_cluster().
979          *
980          * As xfs_ifree_cluser() must gather all inodes that are active in the
981          * cache to mark them stale, if we hit this case we don't actually want
982          * to do IO here - we want the inode marked stale so we can simply
983          * reclaim it.  Hence if we get an EAGAIN error here,  just unlock the
984          * inode, back off and try again.  Hopefully the next pass through will
985          * see the stale flag set on the inode.
986          */
987         error = xfs_iflush(ip, &bp);
988         if (error == -EAGAIN) {
989                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
990                 /* backoff longer than in xfs_ifree_cluster */
991                 delay(2);
992                 goto restart;
993         }
994 
995         if (!error) {
996                 error = xfs_bwrite(bp);
997                 xfs_buf_relse(bp);
998         }
999 
1000         xfs_iflock(ip);
1001 reclaim:
1002         /*
1003          * Because we use RCU freeing we need to ensure the inode always appears
1004          * to be reclaimed with an invalid inode number when in the free state.
1005          * We do this as early as possible under the ILOCK and flush lock so
1006          * that xfs_iflush_cluster() can be guaranteed to detect races with us
1007          * here. By doing this, we guarantee that once xfs_iflush_cluster has
1008          * locked both the XFS_ILOCK and the flush lock that it will see either
1009          * a valid, flushable inode that will serialise correctly against the
1010          * locks below, or it will see a clean (and invalid) inode that it can
1011          * skip.
1012          */
1013         spin_lock(&ip->i_flags_lock);
1014         ip->i_flags = XFS_IRECLAIM;
1015         ip->i_ino = 0;
1016         spin_unlock(&ip->i_flags_lock);
1017 
1018         xfs_ifunlock(ip);
1019         xfs_iunlock(ip, XFS_ILOCK_EXCL);
1020 
1021         XFS_STATS_INC(ip->i_mount, xs_ig_reclaims);
1022         /*
1023          * Remove the inode from the per-AG radix tree.
1024          *
1025          * Because radix_tree_delete won't complain even if the item was never
1026          * added to the tree assert that it's been there before to catch
1027          * problems with the inode life time early on.
1028          */
1029         spin_lock(&pag->pag_ici_lock);
1030         if (!radix_tree_delete(&pag->pag_ici_root,
1031                                 XFS_INO_TO_AGINO(ip->i_mount, ino)))
1032                 ASSERT(0);
1033         xfs_perag_clear_reclaim_tag(pag);
1034         spin_unlock(&pag->pag_ici_lock);
1035 
1036         /*
1037          * Here we do an (almost) spurious inode lock in order to coordinate
1038          * with inode cache radix tree lookups.  This is because the lookup
1039          * can reference the inodes in the cache without taking references.
1040          *
1041          * We make that OK here by ensuring that we wait until the inode is
1042          * unlocked after the lookup before we go ahead and free it.
1043          */
1044         xfs_ilock(ip, XFS_ILOCK_EXCL);
1045         xfs_qm_dqdetach(ip);
1046         xfs_iunlock(ip, XFS_ILOCK_EXCL);
1047 
1048         __xfs_inode_free(ip);
1049         return error;
1050 
1051 out_ifunlock:
1052         xfs_ifunlock(ip);
1053 out:
1054         xfs_iflags_clear(ip, XFS_IRECLAIM);
1055         xfs_iunlock(ip, XFS_ILOCK_EXCL);
1056         /*
1057          * We could return -EAGAIN here to make reclaim rescan the inode tree in
1058          * a short while. However, this just burns CPU time scanning the tree
1059          * waiting for IO to complete and the reclaim work never goes back to
1060          * the idle state. Instead, return 0 to let the next scheduled
1061          * background reclaim attempt to reclaim the inode again.
1062          */
1063         return 0;
1064 }
1065 
1066 /*
1067  * Walk the AGs and reclaim the inodes in them. Even if the filesystem is
1068  * corrupted, we still want to try to reclaim all the inodes. If we don't,
1069  * then a shut down during filesystem unmount reclaim walk leak all the
1070  * unreclaimed inodes.
1071  */
1072 STATIC int
1073 xfs_reclaim_inodes_ag(
1074         struct xfs_mount        *mp,
1075         int                     flags,
1076         int                     *nr_to_scan)
1077 {
1078         struct xfs_perag        *pag;
1079         int                     error = 0;
1080         int                     last_error = 0;
1081         xfs_agnumber_t          ag;
1082         int                     trylock = flags & SYNC_TRYLOCK;
1083         int                     skipped;
1084 
1085 restart:
1086         ag = 0;
1087         skipped = 0;
1088         while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
1089                 unsigned long   first_index = 0;
1090                 int             done = 0;
1091                 int             nr_found = 0;
1092 
1093                 ag = pag->pag_agno + 1;
1094 
1095                 if (trylock) {
1096                         if (!mutex_trylock(&pag->pag_ici_reclaim_lock)) {
1097                                 skipped++;
1098                                 xfs_perag_put(pag);
1099                                 continue;
1100                         }
1101                         first_index = pag->pag_ici_reclaim_cursor;
1102                 } else
1103                         mutex_lock(&pag->pag_ici_reclaim_lock);
1104 
1105                 do {
1106                         struct xfs_inode *batch[XFS_LOOKUP_BATCH];
1107                         int     i;
1108 
1109                         rcu_read_lock();
1110                         nr_found = radix_tree_gang_lookup_tag(
1111                                         &pag->pag_ici_root,
1112                                         (void **)batch, first_index,
1113                                         XFS_LOOKUP_BATCH,
1114                                         XFS_ICI_RECLAIM_TAG);
1115                         if (!nr_found) {
1116                                 done = 1;
1117                                 rcu_read_unlock();
1118                                 break;
1119                         }
1120 
1121                         /*
1122                          * Grab the inodes before we drop the lock. if we found
1123                          * nothing, nr == 0 and the loop will be skipped.
1124                          */
1125                         for (i = 0; i < nr_found; i++) {
1126                                 struct xfs_inode *ip = batch[i];
1127 
1128                                 if (done || xfs_reclaim_inode_grab(ip, flags))
1129                                         batch[i] = NULL;
1130 
1131                                 /*
1132                                  * Update the index for the next lookup. Catch
1133                                  * overflows into the next AG range which can
1134                                  * occur if we have inodes in the last block of
1135                                  * the AG and we are currently pointing to the
1136                                  * last inode.
1137                                  *
1138                                  * Because we may see inodes that are from the
1139                                  * wrong AG due to RCU freeing and
1140                                  * reallocation, only update the index if it
1141                                  * lies in this AG. It was a race that lead us
1142                                  * to see this inode, so another lookup from
1143                                  * the same index will not find it again.
1144                                  */
1145                                 if (XFS_INO_TO_AGNO(mp, ip->i_ino) !=
1146                                                                 pag->pag_agno)
1147                                         continue;
1148                                 first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
1149                                 if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
1150                                         done = 1;
1151                         }
1152 
1153                         /* unlock now we've grabbed the inodes. */
1154                         rcu_read_unlock();
1155 
1156                         for (i = 0; i < nr_found; i++) {
1157                                 if (!batch[i])
1158                                         continue;
1159                                 error = xfs_reclaim_inode(batch[i], pag, flags);
1160                                 if (error && last_error != -EFSCORRUPTED)
1161                                         last_error = error;
1162                         }
1163 
1164                         *nr_to_scan -= XFS_LOOKUP_BATCH;
1165 
1166                         cond_resched();
1167 
1168                 } while (nr_found && !done && *nr_to_scan > 0);
1169 
1170                 if (trylock && !done)
1171                         pag->pag_ici_reclaim_cursor = first_index;
1172                 else
1173                         pag->pag_ici_reclaim_cursor = 0;
1174                 mutex_unlock(&pag->pag_ici_reclaim_lock);
1175                 xfs_perag_put(pag);
1176         }
1177 
1178         /*
1179          * if we skipped any AG, and we still have scan count remaining, do
1180          * another pass this time using blocking reclaim semantics (i.e
1181          * waiting on the reclaim locks and ignoring the reclaim cursors). This
1182          * ensure that when we get more reclaimers than AGs we block rather
1183          * than spin trying to execute reclaim.
1184          */
1185         if (skipped && (flags & SYNC_WAIT) && *nr_to_scan > 0) {
1186                 trylock = 0;
1187                 goto restart;
1188         }
1189         return last_error;
1190 }
1191 
1192 int
1193 xfs_reclaim_inodes(
1194         xfs_mount_t     *mp,
1195         int             mode)
1196 {
1197         int             nr_to_scan = INT_MAX;
1198 
1199         return xfs_reclaim_inodes_ag(mp, mode, &nr_to_scan);
1200 }
1201 
1202 /*
1203  * Scan a certain number of inodes for reclaim.
1204  *
1205  * When called we make sure that there is a background (fast) inode reclaim in
1206  * progress, while we will throttle the speed of reclaim via doing synchronous
1207  * reclaim of inodes. That means if we come across dirty inodes, we wait for
1208  * them to be cleaned, which we hope will not be very long due to the
1209  * background walker having already kicked the IO off on those dirty inodes.
1210  */
1211 long
1212 xfs_reclaim_inodes_nr(
1213         struct xfs_mount        *mp,
1214         int                     nr_to_scan)
1215 {
1216         /* kick background reclaimer and push the AIL */
1217         xfs_reclaim_work_queue(mp);
1218         xfs_ail_push_all(mp->m_ail);
1219 
1220         return xfs_reclaim_inodes_ag(mp, SYNC_TRYLOCK | SYNC_WAIT, &nr_to_scan);
1221 }
1222 
1223 /*
1224  * Return the number of reclaimable inodes in the filesystem for
1225  * the shrinker to determine how much to reclaim.
1226  */
1227 int
1228 xfs_reclaim_inodes_count(
1229         struct xfs_mount        *mp)
1230 {
1231         struct xfs_perag        *pag;
1232         xfs_agnumber_t          ag = 0;
1233         int                     reclaimable = 0;
1234 
1235         while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
1236                 ag = pag->pag_agno + 1;
1237                 reclaimable += pag->pag_ici_reclaimable;
1238                 xfs_perag_put(pag);
1239         }
1240         return reclaimable;
1241 }
1242 
1243 STATIC int
1244 xfs_inode_match_id(
1245         struct xfs_inode        *ip,
1246         struct xfs_eofblocks    *eofb)
1247 {
1248         if ((eofb->eof_flags & XFS_EOF_FLAGS_UID) &&
1249             !uid_eq(VFS_I(ip)->i_uid, eofb->eof_uid))
1250                 return 0;
1251 
1252         if ((eofb->eof_flags & XFS_EOF_FLAGS_GID) &&
1253             !gid_eq(VFS_I(ip)->i_gid, eofb->eof_gid))
1254                 return 0;
1255 
1256         if ((eofb->eof_flags & XFS_EOF_FLAGS_PRID) &&
1257             xfs_get_projid(ip) != eofb->eof_prid)
1258                 return 0;
1259 
1260         return 1;
1261 }
1262 
1263 /*
1264  * A union-based inode filtering algorithm. Process the inode if any of the
1265  * criteria match. This is for global/internal scans only.
1266  */
1267 STATIC int
1268 xfs_inode_match_id_union(
1269         struct xfs_inode        *ip,
1270         struct xfs_eofblocks    *eofb)
1271 {
1272         if ((eofb->eof_flags & XFS_EOF_FLAGS_UID) &&
1273             uid_eq(VFS_I(ip)->i_uid, eofb->eof_uid))
1274                 return 1;
1275 
1276         if ((eofb->eof_flags & XFS_EOF_FLAGS_GID) &&
1277             gid_eq(VFS_I(ip)->i_gid, eofb->eof_gid))
1278                 return 1;
1279 
1280         if ((eofb->eof_flags & XFS_EOF_FLAGS_PRID) &&
1281             xfs_get_projid(ip) == eofb->eof_prid)
1282                 return 1;
1283 
1284         return 0;
1285 }
1286 
1287 STATIC int
1288 xfs_inode_free_eofblocks(
1289         struct xfs_inode        *ip,
1290         int                     flags,
1291         void                    *args)
1292 {
1293         int ret;
1294         struct xfs_eofblocks *eofb = args;
1295         bool need_iolock = true;
1296         int match;
1297 
1298         ASSERT(!eofb || (eofb && eofb->eof_scan_owner != 0));
1299 
1300         if (!xfs_can_free_eofblocks(ip, false)) {
1301                 /* inode could be preallocated or append-only */
1302                 trace_xfs_inode_free_eofblocks_invalid(ip);
1303                 xfs_inode_clear_eofblocks_tag(ip);
1304                 return 0;
1305         }
1306 
1307         /*
1308          * If the mapping is dirty the operation can block and wait for some
1309          * time. Unless we are waiting, skip it.
1310          */
1311         if (!(flags & SYNC_WAIT) &&
1312             mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_DIRTY))
1313                 return 0;
1314 
1315         if (eofb) {
1316                 if (eofb->eof_flags & XFS_EOF_FLAGS_UNION)
1317                         match = xfs_inode_match_id_union(ip, eofb);
1318                 else
1319                         match = xfs_inode_match_id(ip, eofb);
1320                 if (!match)
1321                         return 0;
1322 
1323                 /* skip the inode if the file size is too small */
1324                 if (eofb->eof_flags & XFS_EOF_FLAGS_MINFILESIZE &&
1325                     XFS_ISIZE(ip) < eofb->eof_min_file_size)
1326                         return 0;
1327 
1328                 /*
1329                  * A scan owner implies we already hold the iolock. Skip it in
1330                  * xfs_free_eofblocks() to avoid deadlock. This also eliminates
1331                  * the possibility of EAGAIN being returned.
1332                  */
1333                 if (eofb->eof_scan_owner == ip->i_ino)
1334                         need_iolock = false;
1335         }
1336 
1337         ret = xfs_free_eofblocks(ip->i_mount, ip, need_iolock);
1338 
1339         /* don't revisit the inode if we're not waiting */
1340         if (ret == -EAGAIN && !(flags & SYNC_WAIT))
1341                 ret = 0;
1342 
1343         return ret;
1344 }
1345 
1346 int
1347 xfs_icache_free_eofblocks(
1348         struct xfs_mount        *mp,
1349         struct xfs_eofblocks    *eofb)
1350 {
1351         int flags = SYNC_TRYLOCK;
1352 
1353         if (eofb && (eofb->eof_flags & XFS_EOF_FLAGS_SYNC))
1354                 flags = SYNC_WAIT;
1355 
1356         return xfs_inode_ag_iterator_tag(mp, xfs_inode_free_eofblocks, flags,
1357                                          eofb, XFS_ICI_EOFBLOCKS_TAG);
1358 }
1359 
1360 /*
1361  * Run eofblocks scans on the quotas applicable to the inode. For inodes with
1362  * multiple quotas, we don't know exactly which quota caused an allocation
1363  * failure. We make a best effort by including each quota under low free space
1364  * conditions (less than 1% free space) in the scan.
1365  */
1366 int
1367 xfs_inode_free_quota_eofblocks(
1368         struct xfs_inode *ip)
1369 {
1370         int scan = 0;
1371         struct xfs_eofblocks eofb = {0};
1372         struct xfs_dquot *dq;
1373 
1374         ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
1375 
1376         /*
1377          * Set the scan owner to avoid a potential livelock. Otherwise, the scan
1378          * can repeatedly trylock on the inode we're currently processing. We
1379          * run a sync scan to increase effectiveness and use the union filter to
1380          * cover all applicable quotas in a single scan.
1381          */
1382         eofb.eof_scan_owner = ip->i_ino;
1383         eofb.eof_flags = XFS_EOF_FLAGS_UNION|XFS_EOF_FLAGS_SYNC;
1384 
1385         if (XFS_IS_UQUOTA_ENFORCED(ip->i_mount)) {
1386                 dq = xfs_inode_dquot(ip, XFS_DQ_USER);
1387                 if (dq && xfs_dquot_lowsp(dq)) {
1388                         eofb.eof_uid = VFS_I(ip)->i_uid;
1389                         eofb.eof_flags |= XFS_EOF_FLAGS_UID;
1390                         scan = 1;
1391                 }
1392         }
1393 
1394         if (XFS_IS_GQUOTA_ENFORCED(ip->i_mount)) {
1395                 dq = xfs_inode_dquot(ip, XFS_DQ_GROUP);
1396                 if (dq && xfs_dquot_lowsp(dq)) {
1397                         eofb.eof_gid = VFS_I(ip)->i_gid;
1398                         eofb.eof_flags |= XFS_EOF_FLAGS_GID;
1399                         scan = 1;
1400                 }
1401         }
1402 
1403         if (scan)
1404                 xfs_icache_free_eofblocks(ip->i_mount, &eofb);
1405 
1406         return scan;
1407 }
1408 
1409 void
1410 xfs_inode_set_eofblocks_tag(
1411         xfs_inode_t     *ip)
1412 {
1413         struct xfs_mount *mp = ip->i_mount;
1414         struct xfs_perag *pag;
1415         int tagged;
1416 
1417         pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
1418         spin_lock(&pag->pag_ici_lock);
1419         trace_xfs_inode_set_eofblocks_tag(ip);
1420 
1421         tagged = radix_tree_tagged(&pag->pag_ici_root,
1422                                    XFS_ICI_EOFBLOCKS_TAG);
1423         radix_tree_tag_set(&pag->pag_ici_root,
1424                            XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
1425                            XFS_ICI_EOFBLOCKS_TAG);
1426         if (!tagged) {
1427                 /* propagate the eofblocks tag up into the perag radix tree */
1428                 spin_lock(&ip->i_mount->m_perag_lock);
1429                 radix_tree_tag_set(&ip->i_mount->m_perag_tree,
1430                                    XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
1431                                    XFS_ICI_EOFBLOCKS_TAG);
1432                 spin_unlock(&ip->i_mount->m_perag_lock);
1433 
1434                 /* kick off background trimming */
1435                 xfs_queue_eofblocks(ip->i_mount);
1436 
1437                 trace_xfs_perag_set_eofblocks(ip->i_mount, pag->pag_agno,
1438                                               -1, _RET_IP_);
1439         }
1440 
1441         spin_unlock(&pag->pag_ici_lock);
1442         xfs_perag_put(pag);
1443 }
1444 
1445 void
1446 xfs_inode_clear_eofblocks_tag(
1447         xfs_inode_t     *ip)
1448 {
1449         struct xfs_mount *mp = ip->i_mount;
1450         struct xfs_perag *pag;
1451 
1452         pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
1453         spin_lock(&pag->pag_ici_lock);
1454         trace_xfs_inode_clear_eofblocks_tag(ip);
1455 
1456         radix_tree_tag_clear(&pag->pag_ici_root,
1457                              XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
1458                              XFS_ICI_EOFBLOCKS_TAG);
1459         if (!radix_tree_tagged(&pag->pag_ici_root, XFS_ICI_EOFBLOCKS_TAG)) {
1460                 /* clear the eofblocks tag from the perag radix tree */
1461                 spin_lock(&ip->i_mount->m_perag_lock);
1462                 radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
1463                                      XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
1464                                      XFS_ICI_EOFBLOCKS_TAG);
1465                 spin_unlock(&ip->i_mount->m_perag_lock);
1466                 trace_xfs_perag_clear_eofblocks(ip->i_mount, pag->pag_agno,
1467                                                -1, _RET_IP_);
1468         }
1469 
1470         spin_unlock(&pag->pag_ici_lock);
1471         xfs_perag_put(pag);
1472 }
1473 
1474 

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