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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 STATIC void __xfs_inode_clear_reclaim_tag(struct xfs_mount *mp,
41 				struct xfs_perag *pag, struct xfs_inode *ip);
42 
43 /*
44  * Allocate and initialise an xfs_inode.
45  */
46 struct xfs_inode *
xfs_inode_alloc(struct xfs_mount * mp,xfs_ino_t ino)47 xfs_inode_alloc(
48 	struct xfs_mount	*mp,
49 	xfs_ino_t		ino)
50 {
51 	struct xfs_inode	*ip;
52 
53 	/*
54 	 * if this didn't occur in transactions, we could use
55 	 * KM_MAYFAIL and return NULL here on ENOMEM. Set the
56 	 * code up to do this anyway.
57 	 */
58 	ip = kmem_zone_alloc(xfs_inode_zone, KM_SLEEP);
59 	if (!ip)
60 		return NULL;
61 	if (inode_init_always(mp->m_super, VFS_I(ip))) {
62 		kmem_zone_free(xfs_inode_zone, ip);
63 		return NULL;
64 	}
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(xfs_icdinode_t));
83 
84 	return ip;
85 }
86 
87 STATIC void
xfs_inode_free_callback(struct rcu_head * head)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 	kmem_zone_free(xfs_inode_zone, ip);
95 }
96 
97 void
xfs_inode_free(struct xfs_inode * ip)98 xfs_inode_free(
99 	struct xfs_inode	*ip)
100 {
101 	switch (ip->i_d.di_mode & S_IFMT) {
102 	case S_IFREG:
103 	case S_IFDIR:
104 	case S_IFLNK:
105 		xfs_idestroy_fork(ip, XFS_DATA_FORK);
106 		break;
107 	}
108 
109 	if (ip->i_afp)
110 		xfs_idestroy_fork(ip, XFS_ATTR_FORK);
111 
112 	if (ip->i_itemp) {
113 		ASSERT(!(ip->i_itemp->ili_item.li_flags & XFS_LI_IN_AIL));
114 		xfs_inode_item_destroy(ip);
115 		ip->i_itemp = NULL;
116 	}
117 
118 	/*
119 	 * Because we use RCU freeing we need to ensure the inode always
120 	 * appears to be reclaimed with an invalid inode number when in the
121 	 * free state. The ip->i_flags_lock provides the barrier against lookup
122 	 * races.
123 	 */
124 	spin_lock(&ip->i_flags_lock);
125 	ip->i_flags = XFS_IRECLAIM;
126 	ip->i_ino = 0;
127 	spin_unlock(&ip->i_flags_lock);
128 
129 	/* asserts to verify all state is correct here */
130 	ASSERT(atomic_read(&ip->i_pincount) == 0);
131 	ASSERT(!xfs_isiflocked(ip));
132 	XFS_STATS_DEC(ip->i_mount, vn_active);
133 
134 	call_rcu(&VFS_I(ip)->i_rcu, xfs_inode_free_callback);
135 }
136 
137 /*
138  * If we are allocating a new inode, then check what was returned is
139  * actually a free, empty inode. If we are not allocating an inode,
140  * then check we didn't find a free inode.
141  *
142  * Returns:
143  *	0		if the inode free state matches the lookup context
144  *	-ENOENT		if the inode is free and we are not allocating
145  *	-EFSCORRUPTED	if there is any state mismatch at all
146  */
147 static int
xfs_iget_check_free_state(struct xfs_inode * ip,int flags)148 xfs_iget_check_free_state(
149 	struct xfs_inode	*ip,
150 	int			flags)
151 {
152 	if (flags & XFS_IGET_CREATE) {
153 		/* should be a free inode */
154 		if (ip->i_d.di_mode != 0) {
155 			xfs_warn(ip->i_mount,
156 "Corruption detected! Free inode 0x%llx not marked free! (mode 0x%x)",
157 				ip->i_ino, ip->i_d.di_mode);
158 			return -EFSCORRUPTED;
159 		}
160 
161 		if (ip->i_d.di_nblocks != 0) {
162 			xfs_warn(ip->i_mount,
163 "Corruption detected! Free inode 0x%llx has blocks allocated!",
164 				ip->i_ino);
165 			return -EFSCORRUPTED;
166 		}
167 		return 0;
168 	}
169 
170 	/* should be an allocated inode */
171 	if (ip->i_d.di_mode == 0)
172 		return -ENOENT;
173 
174 	return 0;
175 }
176 
177 /*
178  * Check the validity of the inode we just found it the cache
179  */
180 static int
xfs_iget_cache_hit(struct xfs_perag * pag,struct xfs_inode * ip,xfs_ino_t ino,int flags,int lock_flags)181 xfs_iget_cache_hit(
182 	struct xfs_perag	*pag,
183 	struct xfs_inode	*ip,
184 	xfs_ino_t		ino,
185 	int			flags,
186 	int			lock_flags) __releases(RCU)
187 {
188 	struct inode		*inode = VFS_I(ip);
189 	struct xfs_mount	*mp = ip->i_mount;
190 	int			error;
191 
192 	/*
193 	 * check for re-use of an inode within an RCU grace period due to the
194 	 * radix tree nodes not being updated yet. We monitor for this by
195 	 * setting the inode number to zero before freeing the inode structure.
196 	 * If the inode has been reallocated and set up, then the inode number
197 	 * will not match, so check for that, too.
198 	 */
199 	spin_lock(&ip->i_flags_lock);
200 	if (ip->i_ino != ino) {
201 		trace_xfs_iget_skip(ip);
202 		XFS_STATS_INC(mp, xs_ig_frecycle);
203 		error = -EAGAIN;
204 		goto out_error;
205 	}
206 
207 
208 	/*
209 	 * If we are racing with another cache hit that is currently
210 	 * instantiating this inode or currently recycling it out of
211 	 * reclaimabe state, wait for the initialisation to complete
212 	 * before continuing.
213 	 *
214 	 * XXX(hch): eventually we should do something equivalent to
215 	 *	     wait_on_inode to wait for these flags to be cleared
216 	 *	     instead of polling for it.
217 	 */
218 	if (ip->i_flags & (XFS_INEW|XFS_IRECLAIM)) {
219 		trace_xfs_iget_skip(ip);
220 		XFS_STATS_INC(mp, xs_ig_frecycle);
221 		error = -EAGAIN;
222 		goto out_error;
223 	}
224 
225 	/*
226 	 * Check the inode free state is valid. This also detects lookup
227 	 * racing with unlinks.
228 	 */
229 	error = xfs_iget_check_free_state(ip, flags);
230 	if (error)
231 		goto out_error;
232 
233 	/*
234 	 * If IRECLAIMABLE is set, we've torn down the VFS inode already.
235 	 * Need to carefully get it back into useable state.
236 	 */
237 	if (ip->i_flags & XFS_IRECLAIMABLE) {
238 		trace_xfs_iget_reclaim(ip);
239 
240 		/*
241 		 * We need to set XFS_IRECLAIM to prevent xfs_reclaim_inode
242 		 * from stomping over us while we recycle the inode.  We can't
243 		 * clear the radix tree reclaimable tag yet as it requires
244 		 * pag_ici_lock to be held exclusive.
245 		 */
246 		ip->i_flags |= XFS_IRECLAIM;
247 
248 		spin_unlock(&ip->i_flags_lock);
249 		rcu_read_unlock();
250 
251 		error = inode_init_always(mp->m_super, inode);
252 		if (error) {
253 			bool wake;
254 			/*
255 			 * Re-initializing the inode failed, and we are in deep
256 			 * trouble.  Try to re-add it to the reclaim list.
257 			 */
258 			rcu_read_lock();
259 			spin_lock(&ip->i_flags_lock);
260 			wake = !!__xfs_iflags_test(ip, XFS_INEW);
261 			ip->i_flags &= ~(XFS_INEW | XFS_IRECLAIM);
262 			if (wake)
263 				wake_up_bit(&ip->i_flags, __XFS_INEW_BIT);
264 			ASSERT(ip->i_flags & XFS_IRECLAIMABLE);
265 			trace_xfs_iget_reclaim_fail(ip);
266 			goto out_error;
267 		}
268 
269 		spin_lock(&pag->pag_ici_lock);
270 		spin_lock(&ip->i_flags_lock);
271 
272 		/*
273 		 * Clear the per-lifetime state in the inode as we are now
274 		 * effectively a new inode and need to return to the initial
275 		 * state before reuse occurs.
276 		 */
277 		ip->i_flags &= ~XFS_IRECLAIM_RESET_FLAGS;
278 		ip->i_flags |= XFS_INEW;
279 		__xfs_inode_clear_reclaim_tag(mp, pag, ip);
280 		inode->i_state = I_NEW;
281 
282 		ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
283 		mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
284 
285 		spin_unlock(&ip->i_flags_lock);
286 		spin_unlock(&pag->pag_ici_lock);
287 	} else {
288 		/* If the VFS inode is being torn down, pause and try again. */
289 		if (!igrab(inode)) {
290 			trace_xfs_iget_skip(ip);
291 			error = -EAGAIN;
292 			goto out_error;
293 		}
294 
295 		/* We've got a live one. */
296 		spin_unlock(&ip->i_flags_lock);
297 		rcu_read_unlock();
298 		trace_xfs_iget_hit(ip);
299 	}
300 
301 	if (lock_flags != 0)
302 		xfs_ilock(ip, lock_flags);
303 
304 	xfs_iflags_clear(ip, XFS_ISTALE | XFS_IDONTCACHE);
305 	XFS_STATS_INC(mp, xs_ig_found);
306 
307 	return 0;
308 
309 out_error:
310 	spin_unlock(&ip->i_flags_lock);
311 	rcu_read_unlock();
312 	return error;
313 }
314 
315 
316 static int
xfs_iget_cache_miss(struct xfs_mount * mp,struct xfs_perag * pag,xfs_trans_t * tp,xfs_ino_t ino,struct xfs_inode ** ipp,int flags,int lock_flags)317 xfs_iget_cache_miss(
318 	struct xfs_mount	*mp,
319 	struct xfs_perag	*pag,
320 	xfs_trans_t		*tp,
321 	xfs_ino_t		ino,
322 	struct xfs_inode	**ipp,
323 	int			flags,
324 	int			lock_flags)
325 {
326 	struct xfs_inode	*ip;
327 	int			error;
328 	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, ino);
329 	int			iflags;
330 
331 	ip = xfs_inode_alloc(mp, ino);
332 	if (!ip)
333 		return -ENOMEM;
334 
335 	error = xfs_iread(mp, tp, ip, flags);
336 	if (error)
337 		goto out_destroy;
338 
339 	trace_xfs_iget_miss(ip);
340 
341 
342 	/*
343 	 * Check the inode free state is valid. This also detects lookup
344 	 * racing with unlinks.
345 	 */
346 	error = xfs_iget_check_free_state(ip, flags);
347 	if (error)
348 		goto out_destroy;
349 
350 	/*
351 	 * Preload the radix tree so we can insert safely under the
352 	 * write spinlock. Note that we cannot sleep inside the preload
353 	 * region. Since we can be called from transaction context, don't
354 	 * recurse into the file system.
355 	 */
356 	if (radix_tree_preload(GFP_NOFS)) {
357 		error = -EAGAIN;
358 		goto out_destroy;
359 	}
360 
361 	/*
362 	 * Because the inode hasn't been added to the radix-tree yet it can't
363 	 * be found by another thread, so we can do the non-sleeping lock here.
364 	 */
365 	if (lock_flags) {
366 		if (!xfs_ilock_nowait(ip, lock_flags))
367 			BUG();
368 	}
369 
370 	/*
371 	 * These values must be set before inserting the inode into the radix
372 	 * tree as the moment it is inserted a concurrent lookup (allowed by the
373 	 * RCU locking mechanism) can find it and that lookup must see that this
374 	 * is an inode currently under construction (i.e. that XFS_INEW is set).
375 	 * The ip->i_flags_lock that protects the XFS_INEW flag forms the
376 	 * memory barrier that ensures this detection works correctly at lookup
377 	 * time.
378 	 */
379 	iflags = XFS_INEW;
380 	if (flags & XFS_IGET_DONTCACHE)
381 		iflags |= XFS_IDONTCACHE;
382 	ip->i_udquot = NULL;
383 	ip->i_gdquot = NULL;
384 	ip->i_pdquot = NULL;
385 	xfs_iflags_set(ip, iflags);
386 
387 	/* insert the new inode */
388 	spin_lock(&pag->pag_ici_lock);
389 	error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
390 	if (unlikely(error)) {
391 		WARN_ON(error != -EEXIST);
392 		XFS_STATS_INC(mp, xs_ig_dup);
393 		error = -EAGAIN;
394 		goto out_preload_end;
395 	}
396 	spin_unlock(&pag->pag_ici_lock);
397 	radix_tree_preload_end();
398 
399 	*ipp = ip;
400 	return 0;
401 
402 out_preload_end:
403 	spin_unlock(&pag->pag_ici_lock);
404 	radix_tree_preload_end();
405 	if (lock_flags)
406 		xfs_iunlock(ip, lock_flags);
407 out_destroy:
408 	__destroy_inode(VFS_I(ip));
409 	xfs_inode_free(ip);
410 	return error;
411 }
412 
413 static void
xfs_inew_wait(struct xfs_inode * ip)414 xfs_inew_wait(
415 	struct xfs_inode	*ip)
416 {
417 	wait_queue_head_t *wq = bit_waitqueue(&ip->i_flags, __XFS_INEW_BIT);
418 	DEFINE_WAIT_BIT(wait, &ip->i_flags, __XFS_INEW_BIT);
419 
420 	do {
421 		prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
422 		if (!xfs_iflags_test(ip, XFS_INEW))
423 			break;
424 		schedule();
425 	} while (true);
426 	finish_wait(wq, &wait.wait);
427 }
428 
429 /*
430  * Look up an inode by number in the given file system.
431  * The inode is looked up in the cache held in each AG.
432  * If the inode is found in the cache, initialise the vfs inode
433  * if necessary.
434  *
435  * If it is not in core, read it in from the file system's device,
436  * add it to the cache and initialise the vfs inode.
437  *
438  * The inode is locked according to the value of the lock_flags parameter.
439  * This flag parameter indicates how and if the inode's IO lock and inode lock
440  * should be taken.
441  *
442  * mp -- the mount point structure for the current file system.  It points
443  *       to the inode hash table.
444  * tp -- a pointer to the current transaction if there is one.  This is
445  *       simply passed through to the xfs_iread() call.
446  * ino -- the number of the inode desired.  This is the unique identifier
447  *        within the file system for the inode being requested.
448  * lock_flags -- flags indicating how to lock the inode.  See the comment
449  *		 for xfs_ilock() for a list of valid values.
450  */
451 int
xfs_iget(xfs_mount_t * mp,xfs_trans_t * tp,xfs_ino_t ino,uint flags,uint lock_flags,xfs_inode_t ** ipp)452 xfs_iget(
453 	xfs_mount_t	*mp,
454 	xfs_trans_t	*tp,
455 	xfs_ino_t	ino,
456 	uint		flags,
457 	uint		lock_flags,
458 	xfs_inode_t	**ipp)
459 {
460 	xfs_inode_t	*ip;
461 	int		error;
462 	xfs_perag_t	*pag;
463 	xfs_agino_t	agino;
464 
465 	/*
466 	 * xfs_reclaim_inode() uses the ILOCK to ensure an inode
467 	 * doesn't get freed while it's being referenced during a
468 	 * radix tree traversal here.  It assumes this function
469 	 * aqcuires only the ILOCK (and therefore it has no need to
470 	 * involve the IOLOCK in this synchronization).
471 	 */
472 	ASSERT((lock_flags & (XFS_IOLOCK_EXCL | XFS_IOLOCK_SHARED)) == 0);
473 
474 	/* reject inode numbers outside existing AGs */
475 	if (!ino || XFS_INO_TO_AGNO(mp, ino) >= mp->m_sb.sb_agcount)
476 		return -EINVAL;
477 
478 	XFS_STATS_INC(mp, xs_ig_attempts);
479 
480 	/* get the perag structure and ensure that it's inode capable */
481 	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
482 	agino = XFS_INO_TO_AGINO(mp, ino);
483 
484 again:
485 	error = 0;
486 	rcu_read_lock();
487 	ip = radix_tree_lookup(&pag->pag_ici_root, agino);
488 
489 	if (ip) {
490 		error = xfs_iget_cache_hit(pag, ip, ino, flags, lock_flags);
491 		if (error)
492 			goto out_error_or_again;
493 	} else {
494 		rcu_read_unlock();
495 		XFS_STATS_INC(mp, xs_ig_missed);
496 
497 		error = xfs_iget_cache_miss(mp, pag, tp, ino, &ip,
498 							flags, lock_flags);
499 		if (error)
500 			goto out_error_or_again;
501 	}
502 	xfs_perag_put(pag);
503 
504 	*ipp = ip;
505 
506 	/*
507 	 * If we have a real type for an on-disk inode, we can setup the inode
508 	 * now.	 If it's a new inode being created, xfs_ialloc will handle it.
509 	 */
510 	if (xfs_iflags_test(ip, XFS_INEW) && ip->i_d.di_mode != 0)
511 		xfs_setup_existing_inode(ip);
512 	return 0;
513 
514 out_error_or_again:
515 	if (error == -EAGAIN) {
516 		delay(1);
517 		goto again;
518 	}
519 	xfs_perag_put(pag);
520 	return error;
521 }
522 
523 /*
524  * The inode lookup is done in batches to keep the amount of lock traffic and
525  * radix tree lookups to a minimum. The batch size is a trade off between
526  * lookup reduction and stack usage. This is in the reclaim path, so we can't
527  * be too greedy.
528  */
529 #define XFS_LOOKUP_BATCH	32
530 
531 STATIC int
xfs_inode_ag_walk_grab(struct xfs_inode * ip,int flags)532 xfs_inode_ag_walk_grab(
533 	struct xfs_inode	*ip,
534 	int			flags)
535 {
536 	struct inode		*inode = VFS_I(ip);
537 	bool			newinos = !!(flags & XFS_AGITER_INEW_WAIT);
538 
539 	ASSERT(rcu_read_lock_held());
540 
541 	/*
542 	 * check for stale RCU freed inode
543 	 *
544 	 * If the inode has been reallocated, it doesn't matter if it's not in
545 	 * the AG we are walking - we are walking for writeback, so if it
546 	 * passes all the "valid inode" checks and is dirty, then we'll write
547 	 * it back anyway.  If it has been reallocated and still being
548 	 * initialised, the XFS_INEW check below will catch it.
549 	 */
550 	spin_lock(&ip->i_flags_lock);
551 	if (!ip->i_ino)
552 		goto out_unlock_noent;
553 
554 	/* avoid new or reclaimable inodes. Leave for reclaim code to flush */
555 	if ((!newinos && __xfs_iflags_test(ip, XFS_INEW)) ||
556 	    __xfs_iflags_test(ip, XFS_IRECLAIMABLE | XFS_IRECLAIM))
557 		goto out_unlock_noent;
558 	spin_unlock(&ip->i_flags_lock);
559 
560 	/* nothing to sync during shutdown */
561 	if (XFS_FORCED_SHUTDOWN(ip->i_mount))
562 		return -EFSCORRUPTED;
563 
564 	/* If we can't grab the inode, it must on it's way to reclaim. */
565 	if (!igrab(inode))
566 		return -ENOENT;
567 
568 	/* inode is valid */
569 	return 0;
570 
571 out_unlock_noent:
572 	spin_unlock(&ip->i_flags_lock);
573 	return -ENOENT;
574 }
575 
576 STATIC int
xfs_inode_ag_walk(struct xfs_mount * mp,struct xfs_perag * pag,int (* execute)(struct xfs_inode * ip,int flags,void * args),int flags,void * args,int tag,int iter_flags)577 xfs_inode_ag_walk(
578 	struct xfs_mount	*mp,
579 	struct xfs_perag	*pag,
580 	int			(*execute)(struct xfs_inode *ip, int flags,
581 					   void *args),
582 	int			flags,
583 	void			*args,
584 	int			tag,
585 	int			iter_flags)
586 {
587 	uint32_t		first_index;
588 	int			last_error = 0;
589 	int			skipped;
590 	int			done;
591 	int			nr_found;
592 
593 restart:
594 	done = 0;
595 	skipped = 0;
596 	first_index = 0;
597 	nr_found = 0;
598 	do {
599 		struct xfs_inode *batch[XFS_LOOKUP_BATCH];
600 		int		error = 0;
601 		int		i;
602 
603 		rcu_read_lock();
604 
605 		if (tag == -1)
606 			nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
607 					(void **)batch, first_index,
608 					XFS_LOOKUP_BATCH);
609 		else
610 			nr_found = radix_tree_gang_lookup_tag(
611 					&pag->pag_ici_root,
612 					(void **) batch, first_index,
613 					XFS_LOOKUP_BATCH, tag);
614 
615 		if (!nr_found) {
616 			rcu_read_unlock();
617 			break;
618 		}
619 
620 		/*
621 		 * Grab the inodes before we drop the lock. if we found
622 		 * nothing, nr == 0 and the loop will be skipped.
623 		 */
624 		for (i = 0; i < nr_found; i++) {
625 			struct xfs_inode *ip = batch[i];
626 
627 			if (done || xfs_inode_ag_walk_grab(ip, iter_flags))
628 				batch[i] = NULL;
629 
630 			/*
631 			 * Update the index for the next lookup. Catch
632 			 * overflows into the next AG range which can occur if
633 			 * we have inodes in the last block of the AG and we
634 			 * are currently pointing to the last inode.
635 			 *
636 			 * Because we may see inodes that are from the wrong AG
637 			 * due to RCU freeing and reallocation, only update the
638 			 * index if it lies in this AG. It was a race that lead
639 			 * us to see this inode, so another lookup from the
640 			 * same index will not find it again.
641 			 */
642 			if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag->pag_agno)
643 				continue;
644 			first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
645 			if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
646 				done = 1;
647 		}
648 
649 		/* unlock now we've grabbed the inodes. */
650 		rcu_read_unlock();
651 
652 		for (i = 0; i < nr_found; i++) {
653 			if (!batch[i])
654 				continue;
655 			if ((iter_flags & XFS_AGITER_INEW_WAIT) &&
656 			    xfs_iflags_test(batch[i], XFS_INEW))
657 				xfs_inew_wait(batch[i]);
658 			error = execute(batch[i], flags, args);
659 			IRELE(batch[i]);
660 			if (error == -EAGAIN) {
661 				skipped++;
662 				continue;
663 			}
664 			if (error && last_error != -EFSCORRUPTED)
665 				last_error = error;
666 		}
667 
668 		/* bail out if the filesystem is corrupted.  */
669 		if (error == -EFSCORRUPTED)
670 			break;
671 
672 		cond_resched();
673 
674 	} while (nr_found && !done);
675 
676 	if (skipped) {
677 		delay(1);
678 		goto restart;
679 	}
680 	return last_error;
681 }
682 
683 /*
684  * Background scanning to trim post-EOF preallocated space. This is queued
685  * based on the 'speculative_prealloc_lifetime' tunable (5m by default).
686  */
687 STATIC void
xfs_queue_eofblocks(struct xfs_mount * mp)688 xfs_queue_eofblocks(
689 	struct xfs_mount *mp)
690 {
691 	rcu_read_lock();
692 	if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_EOFBLOCKS_TAG))
693 		queue_delayed_work(mp->m_eofblocks_workqueue,
694 				   &mp->m_eofblocks_work,
695 				   msecs_to_jiffies(xfs_eofb_secs * 1000));
696 	rcu_read_unlock();
697 }
698 
699 void
xfs_eofblocks_worker(struct work_struct * work)700 xfs_eofblocks_worker(
701 	struct work_struct *work)
702 {
703 	struct xfs_mount *mp = container_of(to_delayed_work(work),
704 				struct xfs_mount, m_eofblocks_work);
705 	xfs_icache_free_eofblocks(mp, NULL);
706 	xfs_queue_eofblocks(mp);
707 }
708 
709 int
xfs_inode_ag_iterator_flags(struct xfs_mount * mp,int (* execute)(struct xfs_inode * ip,int flags,void * args),int flags,void * args,int iter_flags)710 xfs_inode_ag_iterator_flags(
711 	struct xfs_mount	*mp,
712 	int			(*execute)(struct xfs_inode *ip, int flags,
713 					   void *args),
714 	int			flags,
715 	void			*args,
716 	int			iter_flags)
717 {
718 	struct xfs_perag	*pag;
719 	int			error = 0;
720 	int			last_error = 0;
721 	xfs_agnumber_t		ag;
722 
723 	ag = 0;
724 	while ((pag = xfs_perag_get(mp, ag))) {
725 		ag = pag->pag_agno + 1;
726 		error = xfs_inode_ag_walk(mp, pag, execute, flags, args, -1,
727 					  iter_flags);
728 		xfs_perag_put(pag);
729 		if (error) {
730 			last_error = error;
731 			if (error == -EFSCORRUPTED)
732 				break;
733 		}
734 	}
735 	return last_error;
736 }
737 
738 int
xfs_inode_ag_iterator(struct xfs_mount * mp,int (* execute)(struct xfs_inode * ip,int flags,void * args),int flags,void * args)739 xfs_inode_ag_iterator(
740 	struct xfs_mount	*mp,
741 	int			(*execute)(struct xfs_inode *ip, int flags,
742 					   void *args),
743 	int			flags,
744 	void			*args)
745 {
746 	return xfs_inode_ag_iterator_flags(mp, execute, flags, args, 0);
747 }
748 
749 int
xfs_inode_ag_iterator_tag(struct xfs_mount * mp,int (* execute)(struct xfs_inode * ip,int flags,void * args),int flags,void * args,int tag)750 xfs_inode_ag_iterator_tag(
751 	struct xfs_mount	*mp,
752 	int			(*execute)(struct xfs_inode *ip, int flags,
753 					   void *args),
754 	int			flags,
755 	void			*args,
756 	int			tag)
757 {
758 	struct xfs_perag	*pag;
759 	int			error = 0;
760 	int			last_error = 0;
761 	xfs_agnumber_t		ag;
762 
763 	ag = 0;
764 	while ((pag = xfs_perag_get_tag(mp, ag, tag))) {
765 		ag = pag->pag_agno + 1;
766 		error = xfs_inode_ag_walk(mp, pag, execute, flags, args, tag,
767 					  0);
768 		xfs_perag_put(pag);
769 		if (error) {
770 			last_error = error;
771 			if (error == -EFSCORRUPTED)
772 				break;
773 		}
774 	}
775 	return last_error;
776 }
777 
778 /*
779  * Queue a new inode reclaim pass if there are reclaimable inodes and there
780  * isn't a reclaim pass already in progress. By default it runs every 5s based
781  * on the xfs periodic sync default of 30s. Perhaps this should have it's own
782  * tunable, but that can be done if this method proves to be ineffective or too
783  * aggressive.
784  */
785 static void
xfs_reclaim_work_queue(struct xfs_mount * mp)786 xfs_reclaim_work_queue(
787 	struct xfs_mount        *mp)
788 {
789 
790 	rcu_read_lock();
791 	if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
792 		queue_delayed_work(mp->m_reclaim_workqueue, &mp->m_reclaim_work,
793 			msecs_to_jiffies(xfs_syncd_centisecs / 6 * 10));
794 	}
795 	rcu_read_unlock();
796 }
797 
798 /*
799  * This is a fast pass over the inode cache to try to get reclaim moving on as
800  * many inodes as possible in a short period of time. It kicks itself every few
801  * seconds, as well as being kicked by the inode cache shrinker when memory
802  * goes low. It scans as quickly as possible avoiding locked inodes or those
803  * already being flushed, and once done schedules a future pass.
804  */
805 void
xfs_reclaim_worker(struct work_struct * work)806 xfs_reclaim_worker(
807 	struct work_struct *work)
808 {
809 	struct xfs_mount *mp = container_of(to_delayed_work(work),
810 					struct xfs_mount, m_reclaim_work);
811 
812 	xfs_reclaim_inodes(mp, SYNC_TRYLOCK);
813 	xfs_reclaim_work_queue(mp);
814 }
815 
816 static void
__xfs_inode_set_reclaim_tag(struct xfs_perag * pag,struct xfs_inode * ip)817 __xfs_inode_set_reclaim_tag(
818 	struct xfs_perag	*pag,
819 	struct xfs_inode	*ip)
820 {
821 	radix_tree_tag_set(&pag->pag_ici_root,
822 			   XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
823 			   XFS_ICI_RECLAIM_TAG);
824 
825 	if (!pag->pag_ici_reclaimable) {
826 		/* propagate the reclaim tag up into the perag radix tree */
827 		spin_lock(&ip->i_mount->m_perag_lock);
828 		radix_tree_tag_set(&ip->i_mount->m_perag_tree,
829 				XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
830 				XFS_ICI_RECLAIM_TAG);
831 		spin_unlock(&ip->i_mount->m_perag_lock);
832 
833 		/* schedule periodic background inode reclaim */
834 		xfs_reclaim_work_queue(ip->i_mount);
835 
836 		trace_xfs_perag_set_reclaim(ip->i_mount, pag->pag_agno,
837 							-1, _RET_IP_);
838 	}
839 	pag->pag_ici_reclaimable++;
840 }
841 
842 /*
843  * We set the inode flag atomically with the radix tree tag.
844  * Once we get tag lookups on the radix tree, this inode flag
845  * can go away.
846  */
847 void
xfs_inode_set_reclaim_tag(xfs_inode_t * ip)848 xfs_inode_set_reclaim_tag(
849 	xfs_inode_t	*ip)
850 {
851 	struct xfs_mount *mp = ip->i_mount;
852 	struct xfs_perag *pag;
853 
854 	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
855 	spin_lock(&pag->pag_ici_lock);
856 	spin_lock(&ip->i_flags_lock);
857 	__xfs_inode_set_reclaim_tag(pag, ip);
858 	__xfs_iflags_set(ip, XFS_IRECLAIMABLE);
859 	spin_unlock(&ip->i_flags_lock);
860 	spin_unlock(&pag->pag_ici_lock);
861 	xfs_perag_put(pag);
862 }
863 
864 STATIC void
__xfs_inode_clear_reclaim(xfs_perag_t * pag,xfs_inode_t * ip)865 __xfs_inode_clear_reclaim(
866 	xfs_perag_t	*pag,
867 	xfs_inode_t	*ip)
868 {
869 	pag->pag_ici_reclaimable--;
870 	if (!pag->pag_ici_reclaimable) {
871 		/* clear the reclaim tag from the perag radix tree */
872 		spin_lock(&ip->i_mount->m_perag_lock);
873 		radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
874 				XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
875 				XFS_ICI_RECLAIM_TAG);
876 		spin_unlock(&ip->i_mount->m_perag_lock);
877 		trace_xfs_perag_clear_reclaim(ip->i_mount, pag->pag_agno,
878 							-1, _RET_IP_);
879 	}
880 }
881 
882 STATIC void
__xfs_inode_clear_reclaim_tag(xfs_mount_t * mp,xfs_perag_t * pag,xfs_inode_t * ip)883 __xfs_inode_clear_reclaim_tag(
884 	xfs_mount_t	*mp,
885 	xfs_perag_t	*pag,
886 	xfs_inode_t	*ip)
887 {
888 	radix_tree_tag_clear(&pag->pag_ici_root,
889 			XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG);
890 	__xfs_inode_clear_reclaim(pag, ip);
891 }
892 
893 /*
894  * Grab the inode for reclaim exclusively.
895  * Return 0 if we grabbed it, non-zero otherwise.
896  */
897 STATIC int
xfs_reclaim_inode_grab(struct xfs_inode * ip,int flags)898 xfs_reclaim_inode_grab(
899 	struct xfs_inode	*ip,
900 	int			flags)
901 {
902 	ASSERT(rcu_read_lock_held());
903 
904 	/* quick check for stale RCU freed inode */
905 	if (!ip->i_ino)
906 		return 1;
907 
908 	/*
909 	 * If we are asked for non-blocking operation, do unlocked checks to
910 	 * see if the inode already is being flushed or in reclaim to avoid
911 	 * lock traffic.
912 	 */
913 	if ((flags & SYNC_TRYLOCK) &&
914 	    __xfs_iflags_test(ip, XFS_IFLOCK | XFS_IRECLAIM))
915 		return 1;
916 
917 	/*
918 	 * The radix tree lock here protects a thread in xfs_iget from racing
919 	 * with us starting reclaim on the inode.  Once we have the
920 	 * XFS_IRECLAIM flag set it will not touch us.
921 	 *
922 	 * Due to RCU lookup, we may find inodes that have been freed and only
923 	 * have XFS_IRECLAIM set.  Indeed, we may see reallocated inodes that
924 	 * aren't candidates for reclaim at all, so we must check the
925 	 * XFS_IRECLAIMABLE is set first before proceeding to reclaim.
926 	 */
927 	spin_lock(&ip->i_flags_lock);
928 	if (!__xfs_iflags_test(ip, XFS_IRECLAIMABLE) ||
929 	    __xfs_iflags_test(ip, XFS_IRECLAIM)) {
930 		/* not a reclaim candidate. */
931 		spin_unlock(&ip->i_flags_lock);
932 		return 1;
933 	}
934 	__xfs_iflags_set(ip, XFS_IRECLAIM);
935 	spin_unlock(&ip->i_flags_lock);
936 	return 0;
937 }
938 
939 /*
940  * Inodes in different states need to be treated differently. The following
941  * table lists the inode states and the reclaim actions necessary:
942  *
943  *	inode state	     iflush ret		required action
944  *      ---------------      ----------         ---------------
945  *	bad			-		reclaim
946  *	shutdown		EIO		unpin and reclaim
947  *	clean, unpinned		0		reclaim
948  *	stale, unpinned		0		reclaim
949  *	clean, pinned(*)	0		requeue
950  *	stale, pinned		EAGAIN		requeue
951  *	dirty, async		-		requeue
952  *	dirty, sync		0		reclaim
953  *
954  * (*) dgc: I don't think the clean, pinned state is possible but it gets
955  * handled anyway given the order of checks implemented.
956  *
957  * Also, because we get the flush lock first, we know that any inode that has
958  * been flushed delwri has had the flush completed by the time we check that
959  * the inode is clean.
960  *
961  * Note that because the inode is flushed delayed write by AIL pushing, the
962  * flush lock may already be held here and waiting on it can result in very
963  * long latencies.  Hence for sync reclaims, where we wait on the flush lock,
964  * the caller should push the AIL first before trying to reclaim inodes to
965  * minimise the amount of time spent waiting.  For background relaim, we only
966  * bother to reclaim clean inodes anyway.
967  *
968  * Hence the order of actions after gaining the locks should be:
969  *	bad		=> reclaim
970  *	shutdown	=> unpin and reclaim
971  *	pinned, async	=> requeue
972  *	pinned, sync	=> unpin
973  *	stale		=> reclaim
974  *	clean		=> reclaim
975  *	dirty, async	=> requeue
976  *	dirty, sync	=> flush, wait and reclaim
977  */
978 STATIC int
xfs_reclaim_inode(struct xfs_inode * ip,struct xfs_perag * pag,int sync_mode)979 xfs_reclaim_inode(
980 	struct xfs_inode	*ip,
981 	struct xfs_perag	*pag,
982 	int			sync_mode)
983 {
984 	struct xfs_buf		*bp = NULL;
985 	int			error;
986 
987 restart:
988 	error = 0;
989 	xfs_ilock(ip, XFS_ILOCK_EXCL);
990 	if (!xfs_iflock_nowait(ip)) {
991 		if (!(sync_mode & SYNC_WAIT))
992 			goto out;
993 		xfs_iflock(ip);
994 	}
995 
996 	if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
997 		xfs_iunpin_wait(ip);
998 		xfs_iflush_abort(ip, false);
999 		goto reclaim;
1000 	}
1001 	if (xfs_ipincount(ip)) {
1002 		if (!(sync_mode & SYNC_WAIT))
1003 			goto out_ifunlock;
1004 		xfs_iunpin_wait(ip);
1005 	}
1006 	if (xfs_iflags_test(ip, XFS_ISTALE))
1007 		goto reclaim;
1008 	if (xfs_inode_clean(ip))
1009 		goto reclaim;
1010 
1011 	/*
1012 	 * Never flush out dirty data during non-blocking reclaim, as it would
1013 	 * just contend with AIL pushing trying to do the same job.
1014 	 */
1015 	if (!(sync_mode & SYNC_WAIT))
1016 		goto out_ifunlock;
1017 
1018 	/*
1019 	 * Now we have an inode that needs flushing.
1020 	 *
1021 	 * Note that xfs_iflush will never block on the inode buffer lock, as
1022 	 * xfs_ifree_cluster() can lock the inode buffer before it locks the
1023 	 * ip->i_lock, and we are doing the exact opposite here.  As a result,
1024 	 * doing a blocking xfs_imap_to_bp() to get the cluster buffer would
1025 	 * result in an ABBA deadlock with xfs_ifree_cluster().
1026 	 *
1027 	 * As xfs_ifree_cluser() must gather all inodes that are active in the
1028 	 * cache to mark them stale, if we hit this case we don't actually want
1029 	 * to do IO here - we want the inode marked stale so we can simply
1030 	 * reclaim it.  Hence if we get an EAGAIN error here,  just unlock the
1031 	 * inode, back off and try again.  Hopefully the next pass through will
1032 	 * see the stale flag set on the inode.
1033 	 */
1034 	error = xfs_iflush(ip, &bp);
1035 	if (error == -EAGAIN) {
1036 		xfs_iunlock(ip, XFS_ILOCK_EXCL);
1037 		/* backoff longer than in xfs_ifree_cluster */
1038 		delay(2);
1039 		goto restart;
1040 	}
1041 
1042 	if (!error) {
1043 		error = xfs_bwrite(bp);
1044 		xfs_buf_relse(bp);
1045 	}
1046 
1047 	xfs_iflock(ip);
1048 reclaim:
1049 	xfs_ifunlock(ip);
1050 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1051 
1052 	XFS_STATS_INC(ip->i_mount, xs_ig_reclaims);
1053 	/*
1054 	 * Remove the inode from the per-AG radix tree.
1055 	 *
1056 	 * Because radix_tree_delete won't complain even if the item was never
1057 	 * added to the tree assert that it's been there before to catch
1058 	 * problems with the inode life time early on.
1059 	 */
1060 	spin_lock(&pag->pag_ici_lock);
1061 	if (!radix_tree_delete(&pag->pag_ici_root,
1062 				XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino)))
1063 		ASSERT(0);
1064 	__xfs_inode_clear_reclaim(pag, ip);
1065 	spin_unlock(&pag->pag_ici_lock);
1066 
1067 	/*
1068 	 * Here we do an (almost) spurious inode lock in order to coordinate
1069 	 * with inode cache radix tree lookups.  This is because the lookup
1070 	 * can reference the inodes in the cache without taking references.
1071 	 *
1072 	 * We make that OK here by ensuring that we wait until the inode is
1073 	 * unlocked after the lookup before we go ahead and free it.
1074 	 */
1075 	xfs_ilock(ip, XFS_ILOCK_EXCL);
1076 	xfs_qm_dqdetach(ip);
1077 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1078 
1079 	xfs_inode_free(ip);
1080 	return error;
1081 
1082 out_ifunlock:
1083 	xfs_ifunlock(ip);
1084 out:
1085 	xfs_iflags_clear(ip, XFS_IRECLAIM);
1086 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1087 	/*
1088 	 * We could return -EAGAIN here to make reclaim rescan the inode tree in
1089 	 * a short while. However, this just burns CPU time scanning the tree
1090 	 * waiting for IO to complete and the reclaim work never goes back to
1091 	 * the idle state. Instead, return 0 to let the next scheduled
1092 	 * background reclaim attempt to reclaim the inode again.
1093 	 */
1094 	return 0;
1095 }
1096 
1097 /*
1098  * Walk the AGs and reclaim the inodes in them. Even if the filesystem is
1099  * corrupted, we still want to try to reclaim all the inodes. If we don't,
1100  * then a shut down during filesystem unmount reclaim walk leak all the
1101  * unreclaimed inodes.
1102  */
1103 STATIC int
xfs_reclaim_inodes_ag(struct xfs_mount * mp,int flags,int * nr_to_scan)1104 xfs_reclaim_inodes_ag(
1105 	struct xfs_mount	*mp,
1106 	int			flags,
1107 	int			*nr_to_scan)
1108 {
1109 	struct xfs_perag	*pag;
1110 	int			error = 0;
1111 	int			last_error = 0;
1112 	xfs_agnumber_t		ag;
1113 	int			trylock = flags & SYNC_TRYLOCK;
1114 	int			skipped;
1115 
1116 restart:
1117 	ag = 0;
1118 	skipped = 0;
1119 	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
1120 		unsigned long	first_index = 0;
1121 		int		done = 0;
1122 		int		nr_found = 0;
1123 
1124 		ag = pag->pag_agno + 1;
1125 
1126 		if (trylock) {
1127 			if (!mutex_trylock(&pag->pag_ici_reclaim_lock)) {
1128 				skipped++;
1129 				xfs_perag_put(pag);
1130 				continue;
1131 			}
1132 			first_index = pag->pag_ici_reclaim_cursor;
1133 		} else
1134 			mutex_lock(&pag->pag_ici_reclaim_lock);
1135 
1136 		do {
1137 			struct xfs_inode *batch[XFS_LOOKUP_BATCH];
1138 			int	i;
1139 
1140 			rcu_read_lock();
1141 			nr_found = radix_tree_gang_lookup_tag(
1142 					&pag->pag_ici_root,
1143 					(void **)batch, first_index,
1144 					XFS_LOOKUP_BATCH,
1145 					XFS_ICI_RECLAIM_TAG);
1146 			if (!nr_found) {
1147 				done = 1;
1148 				rcu_read_unlock();
1149 				break;
1150 			}
1151 
1152 			/*
1153 			 * Grab the inodes before we drop the lock. if we found
1154 			 * nothing, nr == 0 and the loop will be skipped.
1155 			 */
1156 			for (i = 0; i < nr_found; i++) {
1157 				struct xfs_inode *ip = batch[i];
1158 
1159 				if (done || xfs_reclaim_inode_grab(ip, flags))
1160 					batch[i] = NULL;
1161 
1162 				/*
1163 				 * Update the index for the next lookup. Catch
1164 				 * overflows into the next AG range which can
1165 				 * occur if we have inodes in the last block of
1166 				 * the AG and we are currently pointing to the
1167 				 * last inode.
1168 				 *
1169 				 * Because we may see inodes that are from the
1170 				 * wrong AG due to RCU freeing and
1171 				 * reallocation, only update the index if it
1172 				 * lies in this AG. It was a race that lead us
1173 				 * to see this inode, so another lookup from
1174 				 * the same index will not find it again.
1175 				 */
1176 				if (XFS_INO_TO_AGNO(mp, ip->i_ino) !=
1177 								pag->pag_agno)
1178 					continue;
1179 				first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
1180 				if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
1181 					done = 1;
1182 			}
1183 
1184 			/* unlock now we've grabbed the inodes. */
1185 			rcu_read_unlock();
1186 
1187 			for (i = 0; i < nr_found; i++) {
1188 				if (!batch[i])
1189 					continue;
1190 				error = xfs_reclaim_inode(batch[i], pag, flags);
1191 				if (error && last_error != -EFSCORRUPTED)
1192 					last_error = error;
1193 			}
1194 
1195 			*nr_to_scan -= XFS_LOOKUP_BATCH;
1196 
1197 			cond_resched();
1198 
1199 		} while (nr_found && !done && *nr_to_scan > 0);
1200 
1201 		if (trylock && !done)
1202 			pag->pag_ici_reclaim_cursor = first_index;
1203 		else
1204 			pag->pag_ici_reclaim_cursor = 0;
1205 		mutex_unlock(&pag->pag_ici_reclaim_lock);
1206 		xfs_perag_put(pag);
1207 	}
1208 
1209 	/*
1210 	 * if we skipped any AG, and we still have scan count remaining, do
1211 	 * another pass this time using blocking reclaim semantics (i.e
1212 	 * waiting on the reclaim locks and ignoring the reclaim cursors). This
1213 	 * ensure that when we get more reclaimers than AGs we block rather
1214 	 * than spin trying to execute reclaim.
1215 	 */
1216 	if (skipped && (flags & SYNC_WAIT) && *nr_to_scan > 0) {
1217 		trylock = 0;
1218 		goto restart;
1219 	}
1220 	return last_error;
1221 }
1222 
1223 int
xfs_reclaim_inodes(xfs_mount_t * mp,int mode)1224 xfs_reclaim_inodes(
1225 	xfs_mount_t	*mp,
1226 	int		mode)
1227 {
1228 	int		nr_to_scan = INT_MAX;
1229 
1230 	return xfs_reclaim_inodes_ag(mp, mode, &nr_to_scan);
1231 }
1232 
1233 /*
1234  * Scan a certain number of inodes for reclaim.
1235  *
1236  * When called we make sure that there is a background (fast) inode reclaim in
1237  * progress, while we will throttle the speed of reclaim via doing synchronous
1238  * reclaim of inodes. That means if we come across dirty inodes, we wait for
1239  * them to be cleaned, which we hope will not be very long due to the
1240  * background walker having already kicked the IO off on those dirty inodes.
1241  */
1242 long
xfs_reclaim_inodes_nr(struct xfs_mount * mp,int nr_to_scan)1243 xfs_reclaim_inodes_nr(
1244 	struct xfs_mount	*mp,
1245 	int			nr_to_scan)
1246 {
1247 	/* kick background reclaimer and push the AIL */
1248 	xfs_reclaim_work_queue(mp);
1249 	xfs_ail_push_all(mp->m_ail);
1250 
1251 	return xfs_reclaim_inodes_ag(mp, SYNC_TRYLOCK | SYNC_WAIT, &nr_to_scan);
1252 }
1253 
1254 /*
1255  * Return the number of reclaimable inodes in the filesystem for
1256  * the shrinker to determine how much to reclaim.
1257  */
1258 int
xfs_reclaim_inodes_count(struct xfs_mount * mp)1259 xfs_reclaim_inodes_count(
1260 	struct xfs_mount	*mp)
1261 {
1262 	struct xfs_perag	*pag;
1263 	xfs_agnumber_t		ag = 0;
1264 	int			reclaimable = 0;
1265 
1266 	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
1267 		ag = pag->pag_agno + 1;
1268 		reclaimable += pag->pag_ici_reclaimable;
1269 		xfs_perag_put(pag);
1270 	}
1271 	return reclaimable;
1272 }
1273 
1274 STATIC int
xfs_inode_match_id(struct xfs_inode * ip,struct xfs_eofblocks * eofb)1275 xfs_inode_match_id(
1276 	struct xfs_inode	*ip,
1277 	struct xfs_eofblocks	*eofb)
1278 {
1279 	if ((eofb->eof_flags & XFS_EOF_FLAGS_UID) &&
1280 	    !uid_eq(VFS_I(ip)->i_uid, eofb->eof_uid))
1281 		return 0;
1282 
1283 	if ((eofb->eof_flags & XFS_EOF_FLAGS_GID) &&
1284 	    !gid_eq(VFS_I(ip)->i_gid, eofb->eof_gid))
1285 		return 0;
1286 
1287 	if ((eofb->eof_flags & XFS_EOF_FLAGS_PRID) &&
1288 	    xfs_get_projid(ip) != eofb->eof_prid)
1289 		return 0;
1290 
1291 	return 1;
1292 }
1293 
1294 /*
1295  * A union-based inode filtering algorithm. Process the inode if any of the
1296  * criteria match. This is for global/internal scans only.
1297  */
1298 STATIC int
xfs_inode_match_id_union(struct xfs_inode * ip,struct xfs_eofblocks * eofb)1299 xfs_inode_match_id_union(
1300 	struct xfs_inode	*ip,
1301 	struct xfs_eofblocks	*eofb)
1302 {
1303 	if ((eofb->eof_flags & XFS_EOF_FLAGS_UID) &&
1304 	    uid_eq(VFS_I(ip)->i_uid, eofb->eof_uid))
1305 		return 1;
1306 
1307 	if ((eofb->eof_flags & XFS_EOF_FLAGS_GID) &&
1308 	    gid_eq(VFS_I(ip)->i_gid, eofb->eof_gid))
1309 		return 1;
1310 
1311 	if ((eofb->eof_flags & XFS_EOF_FLAGS_PRID) &&
1312 	    xfs_get_projid(ip) == eofb->eof_prid)
1313 		return 1;
1314 
1315 	return 0;
1316 }
1317 
1318 STATIC int
xfs_inode_free_eofblocks(struct xfs_inode * ip,int flags,void * args)1319 xfs_inode_free_eofblocks(
1320 	struct xfs_inode	*ip,
1321 	int			flags,
1322 	void			*args)
1323 {
1324 	int ret;
1325 	struct xfs_eofblocks *eofb = args;
1326 	bool need_iolock = true;
1327 	int match;
1328 
1329 	ASSERT(!eofb || (eofb && eofb->eof_scan_owner != 0));
1330 
1331 	if (!xfs_can_free_eofblocks(ip, false)) {
1332 		/* inode could be preallocated or append-only */
1333 		trace_xfs_inode_free_eofblocks_invalid(ip);
1334 		xfs_inode_clear_eofblocks_tag(ip);
1335 		return 0;
1336 	}
1337 
1338 	/*
1339 	 * If the mapping is dirty the operation can block and wait for some
1340 	 * time. Unless we are waiting, skip it.
1341 	 */
1342 	if (!(flags & SYNC_WAIT) &&
1343 	    mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_DIRTY))
1344 		return 0;
1345 
1346 	if (eofb) {
1347 		if (eofb->eof_flags & XFS_EOF_FLAGS_UNION)
1348 			match = xfs_inode_match_id_union(ip, eofb);
1349 		else
1350 			match = xfs_inode_match_id(ip, eofb);
1351 		if (!match)
1352 			return 0;
1353 
1354 		/* skip the inode if the file size is too small */
1355 		if (eofb->eof_flags & XFS_EOF_FLAGS_MINFILESIZE &&
1356 		    XFS_ISIZE(ip) < eofb->eof_min_file_size)
1357 			return 0;
1358 
1359 		/*
1360 		 * A scan owner implies we already hold the iolock. Skip it in
1361 		 * xfs_free_eofblocks() to avoid deadlock. This also eliminates
1362 		 * the possibility of EAGAIN being returned.
1363 		 */
1364 		if (eofb->eof_scan_owner == ip->i_ino)
1365 			need_iolock = false;
1366 	}
1367 
1368 	ret = xfs_free_eofblocks(ip->i_mount, ip, need_iolock);
1369 
1370 	/* don't revisit the inode if we're not waiting */
1371 	if (ret == -EAGAIN && !(flags & SYNC_WAIT))
1372 		ret = 0;
1373 
1374 	return ret;
1375 }
1376 
1377 int
xfs_icache_free_eofblocks(struct xfs_mount * mp,struct xfs_eofblocks * eofb)1378 xfs_icache_free_eofblocks(
1379 	struct xfs_mount	*mp,
1380 	struct xfs_eofblocks	*eofb)
1381 {
1382 	int flags = SYNC_TRYLOCK;
1383 
1384 	if (eofb && (eofb->eof_flags & XFS_EOF_FLAGS_SYNC))
1385 		flags = SYNC_WAIT;
1386 
1387 	return xfs_inode_ag_iterator_tag(mp, xfs_inode_free_eofblocks, flags,
1388 					 eofb, XFS_ICI_EOFBLOCKS_TAG);
1389 }
1390 
1391 /*
1392  * Run eofblocks scans on the quotas applicable to the inode. For inodes with
1393  * multiple quotas, we don't know exactly which quota caused an allocation
1394  * failure. We make a best effort by including each quota under low free space
1395  * conditions (less than 1% free space) in the scan.
1396  */
1397 int
xfs_inode_free_quota_eofblocks(struct xfs_inode * ip)1398 xfs_inode_free_quota_eofblocks(
1399 	struct xfs_inode *ip)
1400 {
1401 	int scan = 0;
1402 	struct xfs_eofblocks eofb = {0};
1403 	struct xfs_dquot *dq;
1404 
1405 	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
1406 
1407 	/*
1408 	 * Set the scan owner to avoid a potential livelock. Otherwise, the scan
1409 	 * can repeatedly trylock on the inode we're currently processing. We
1410 	 * run a sync scan to increase effectiveness and use the union filter to
1411 	 * cover all applicable quotas in a single scan.
1412 	 */
1413 	eofb.eof_scan_owner = ip->i_ino;
1414 	eofb.eof_flags = XFS_EOF_FLAGS_UNION|XFS_EOF_FLAGS_SYNC;
1415 
1416 	if (XFS_IS_UQUOTA_ENFORCED(ip->i_mount)) {
1417 		dq = xfs_inode_dquot(ip, XFS_DQ_USER);
1418 		if (dq && xfs_dquot_lowsp(dq)) {
1419 			eofb.eof_uid = VFS_I(ip)->i_uid;
1420 			eofb.eof_flags |= XFS_EOF_FLAGS_UID;
1421 			scan = 1;
1422 		}
1423 	}
1424 
1425 	if (XFS_IS_GQUOTA_ENFORCED(ip->i_mount)) {
1426 		dq = xfs_inode_dquot(ip, XFS_DQ_GROUP);
1427 		if (dq && xfs_dquot_lowsp(dq)) {
1428 			eofb.eof_gid = VFS_I(ip)->i_gid;
1429 			eofb.eof_flags |= XFS_EOF_FLAGS_GID;
1430 			scan = 1;
1431 		}
1432 	}
1433 
1434 	if (scan)
1435 		xfs_icache_free_eofblocks(ip->i_mount, &eofb);
1436 
1437 	return scan;
1438 }
1439 
1440 void
xfs_inode_set_eofblocks_tag(xfs_inode_t * ip)1441 xfs_inode_set_eofblocks_tag(
1442 	xfs_inode_t	*ip)
1443 {
1444 	struct xfs_mount *mp = ip->i_mount;
1445 	struct xfs_perag *pag;
1446 	int tagged;
1447 
1448 	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
1449 	spin_lock(&pag->pag_ici_lock);
1450 	trace_xfs_inode_set_eofblocks_tag(ip);
1451 
1452 	tagged = radix_tree_tagged(&pag->pag_ici_root,
1453 				   XFS_ICI_EOFBLOCKS_TAG);
1454 	radix_tree_tag_set(&pag->pag_ici_root,
1455 			   XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
1456 			   XFS_ICI_EOFBLOCKS_TAG);
1457 	if (!tagged) {
1458 		/* propagate the eofblocks tag up into the perag radix tree */
1459 		spin_lock(&ip->i_mount->m_perag_lock);
1460 		radix_tree_tag_set(&ip->i_mount->m_perag_tree,
1461 				   XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
1462 				   XFS_ICI_EOFBLOCKS_TAG);
1463 		spin_unlock(&ip->i_mount->m_perag_lock);
1464 
1465 		/* kick off background trimming */
1466 		xfs_queue_eofblocks(ip->i_mount);
1467 
1468 		trace_xfs_perag_set_eofblocks(ip->i_mount, pag->pag_agno,
1469 					      -1, _RET_IP_);
1470 	}
1471 
1472 	spin_unlock(&pag->pag_ici_lock);
1473 	xfs_perag_put(pag);
1474 }
1475 
1476 void
xfs_inode_clear_eofblocks_tag(xfs_inode_t * ip)1477 xfs_inode_clear_eofblocks_tag(
1478 	xfs_inode_t	*ip)
1479 {
1480 	struct xfs_mount *mp = ip->i_mount;
1481 	struct xfs_perag *pag;
1482 
1483 	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
1484 	spin_lock(&pag->pag_ici_lock);
1485 	trace_xfs_inode_clear_eofblocks_tag(ip);
1486 
1487 	radix_tree_tag_clear(&pag->pag_ici_root,
1488 			     XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
1489 			     XFS_ICI_EOFBLOCKS_TAG);
1490 	if (!radix_tree_tagged(&pag->pag_ici_root, XFS_ICI_EOFBLOCKS_TAG)) {
1491 		/* clear the eofblocks tag from the perag radix tree */
1492 		spin_lock(&ip->i_mount->m_perag_lock);
1493 		radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
1494 				     XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
1495 				     XFS_ICI_EOFBLOCKS_TAG);
1496 		spin_unlock(&ip->i_mount->m_perag_lock);
1497 		trace_xfs_perag_clear_eofblocks(ip->i_mount, pag->pag_agno,
1498 					       -1, _RET_IP_);
1499 	}
1500 
1501 	spin_unlock(&pag->pag_ici_lock);
1502 	xfs_perag_put(pag);
1503 }
1504 
1505