1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2016 Oracle.  All Rights Reserved.
4  * Author: Darrick J. Wong <darrick.wong@oracle.com>
5  */
6 #include "xfs.h"
7 #include "xfs_fs.h"
8 #include "xfs_shared.h"
9 #include "xfs_format.h"
10 #include "xfs_log_format.h"
11 #include "xfs_trans_resv.h"
12 #include "xfs_mount.h"
13 #include "xfs_defer.h"
14 #include "xfs_trans.h"
15 #include "xfs_buf_item.h"
16 #include "xfs_inode.h"
17 #include "xfs_inode_item.h"
18 #include "xfs_trace.h"
19 #include "xfs_icache.h"
20 #include "xfs_log.h"
21 #include "xfs_rmap.h"
22 #include "xfs_refcount.h"
23 #include "xfs_bmap.h"
24 #include "xfs_alloc.h"
25 #include "xfs_buf.h"
26 #include "xfs_da_format.h"
27 #include "xfs_da_btree.h"
28 #include "xfs_attr.h"
29 
30 static struct kmem_cache	*xfs_defer_pending_cache;
31 
32 /*
33  * Deferred Operations in XFS
34  *
35  * Due to the way locking rules work in XFS, certain transactions (block
36  * mapping and unmapping, typically) have permanent reservations so that
37  * we can roll the transaction to adhere to AG locking order rules and
38  * to unlock buffers between metadata updates.  Prior to rmap/reflink,
39  * the mapping code had a mechanism to perform these deferrals for
40  * extents that were going to be freed; this code makes that facility
41  * more generic.
42  *
43  * When adding the reverse mapping and reflink features, it became
44  * necessary to perform complex remapping multi-transactions to comply
45  * with AG locking order rules, and to be able to spread a single
46  * refcount update operation (an operation on an n-block extent can
47  * update as many as n records!) among multiple transactions.  XFS can
48  * roll a transaction to facilitate this, but using this facility
49  * requires us to log "intent" items in case log recovery needs to
50  * redo the operation, and to log "done" items to indicate that redo
51  * is not necessary.
52  *
53  * Deferred work is tracked in xfs_defer_pending items.  Each pending
54  * item tracks one type of deferred work.  Incoming work items (which
55  * have not yet had an intent logged) are attached to a pending item
56  * on the dop_intake list, where they wait for the caller to finish
57  * the deferred operations.
58  *
59  * Finishing a set of deferred operations is an involved process.  To
60  * start, we define "rolling a deferred-op transaction" as follows:
61  *
62  * > For each xfs_defer_pending item on the dop_intake list,
63  *   - Sort the work items in AG order.  XFS locking
64  *     order rules require us to lock buffers in AG order.
65  *   - Create a log intent item for that type.
66  *   - Attach it to the pending item.
67  *   - Move the pending item from the dop_intake list to the
68  *     dop_pending list.
69  * > Roll the transaction.
70  *
71  * NOTE: To avoid exceeding the transaction reservation, we limit the
72  * number of items that we attach to a given xfs_defer_pending.
73  *
74  * The actual finishing process looks like this:
75  *
76  * > For each xfs_defer_pending in the dop_pending list,
77  *   - Roll the deferred-op transaction as above.
78  *   - Create a log done item for that type, and attach it to the
79  *     log intent item.
80  *   - For each work item attached to the log intent item,
81  *     * Perform the described action.
82  *     * Attach the work item to the log done item.
83  *     * If the result of doing the work was -EAGAIN, ->finish work
84  *       wants a new transaction.  See the "Requesting a Fresh
85  *       Transaction while Finishing Deferred Work" section below for
86  *       details.
87  *
88  * The key here is that we must log an intent item for all pending
89  * work items every time we roll the transaction, and that we must log
90  * a done item as soon as the work is completed.  With this mechanism
91  * we can perform complex remapping operations, chaining intent items
92  * as needed.
93  *
94  * Requesting a Fresh Transaction while Finishing Deferred Work
95  *
96  * If ->finish_item decides that it needs a fresh transaction to
97  * finish the work, it must ask its caller (xfs_defer_finish) for a
98  * continuation.  The most likely cause of this circumstance are the
99  * refcount adjust functions deciding that they've logged enough items
100  * to be at risk of exceeding the transaction reservation.
101  *
102  * To get a fresh transaction, we want to log the existing log done
103  * item to prevent the log intent item from replaying, immediately log
104  * a new log intent item with the unfinished work items, roll the
105  * transaction, and re-call ->finish_item wherever it left off.  The
106  * log done item and the new log intent item must be in the same
107  * transaction or atomicity cannot be guaranteed; defer_finish ensures
108  * that this happens.
109  *
110  * This requires some coordination between ->finish_item and
111  * defer_finish.  Upon deciding to request a new transaction,
112  * ->finish_item should update the current work item to reflect the
113  * unfinished work.  Next, it should reset the log done item's list
114  * count to the number of items finished, and return -EAGAIN.
115  * defer_finish sees the -EAGAIN, logs the new log intent item
116  * with the remaining work items, and leaves the xfs_defer_pending
117  * item at the head of the dop_work queue.  Then it rolls the
118  * transaction and picks up processing where it left off.  It is
119  * required that ->finish_item must be careful to leave enough
120  * transaction reservation to fit the new log intent item.
121  *
122  * This is an example of remapping the extent (E, E+B) into file X at
123  * offset A and dealing with the extent (C, C+B) already being mapped
124  * there:
125  * +-------------------------------------------------+
126  * | Unmap file X startblock C offset A length B     | t0
127  * | Intent to reduce refcount for extent (C, B)     |
128  * | Intent to remove rmap (X, C, A, B)              |
129  * | Intent to free extent (D, 1) (bmbt block)       |
130  * | Intent to map (X, A, B) at startblock E         |
131  * +-------------------------------------------------+
132  * | Map file X startblock E offset A length B       | t1
133  * | Done mapping (X, E, A, B)                       |
134  * | Intent to increase refcount for extent (E, B)   |
135  * | Intent to add rmap (X, E, A, B)                 |
136  * +-------------------------------------------------+
137  * | Reduce refcount for extent (C, B)               | t2
138  * | Done reducing refcount for extent (C, 9)        |
139  * | Intent to reduce refcount for extent (C+9, B-9) |
140  * | (ran out of space after 9 refcount updates)     |
141  * +-------------------------------------------------+
142  * | Reduce refcount for extent (C+9, B+9)           | t3
143  * | Done reducing refcount for extent (C+9, B-9)    |
144  * | Increase refcount for extent (E, B)             |
145  * | Done increasing refcount for extent (E, B)      |
146  * | Intent to free extent (C, B)                    |
147  * | Intent to free extent (F, 1) (refcountbt block) |
148  * | Intent to remove rmap (F, 1, REFC)              |
149  * +-------------------------------------------------+
150  * | Remove rmap (X, C, A, B)                        | t4
151  * | Done removing rmap (X, C, A, B)                 |
152  * | Add rmap (X, E, A, B)                           |
153  * | Done adding rmap (X, E, A, B)                   |
154  * | Remove rmap (F, 1, REFC)                        |
155  * | Done removing rmap (F, 1, REFC)                 |
156  * +-------------------------------------------------+
157  * | Free extent (C, B)                              | t5
158  * | Done freeing extent (C, B)                      |
159  * | Free extent (D, 1)                              |
160  * | Done freeing extent (D, 1)                      |
161  * | Free extent (F, 1)                              |
162  * | Done freeing extent (F, 1)                      |
163  * +-------------------------------------------------+
164  *
165  * If we should crash before t2 commits, log recovery replays
166  * the following intent items:
167  *
168  * - Intent to reduce refcount for extent (C, B)
169  * - Intent to remove rmap (X, C, A, B)
170  * - Intent to free extent (D, 1) (bmbt block)
171  * - Intent to increase refcount for extent (E, B)
172  * - Intent to add rmap (X, E, A, B)
173  *
174  * In the process of recovering, it should also generate and take care
175  * of these intent items:
176  *
177  * - Intent to free extent (C, B)
178  * - Intent to free extent (F, 1) (refcountbt block)
179  * - Intent to remove rmap (F, 1, REFC)
180  *
181  * Note that the continuation requested between t2 and t3 is likely to
182  * reoccur.
183  */
184 
185 static const struct xfs_defer_op_type *defer_op_types[] = {
186 	[XFS_DEFER_OPS_TYPE_BMAP]	= &xfs_bmap_update_defer_type,
187 	[XFS_DEFER_OPS_TYPE_REFCOUNT]	= &xfs_refcount_update_defer_type,
188 	[XFS_DEFER_OPS_TYPE_RMAP]	= &xfs_rmap_update_defer_type,
189 	[XFS_DEFER_OPS_TYPE_FREE]	= &xfs_extent_free_defer_type,
190 	[XFS_DEFER_OPS_TYPE_AGFL_FREE]	= &xfs_agfl_free_defer_type,
191 	[XFS_DEFER_OPS_TYPE_ATTR]	= &xfs_attr_defer_type,
192 };
193 
194 /*
195  * Ensure there's a log intent item associated with this deferred work item if
196  * the operation must be restarted on crash.  Returns 1 if there's a log item;
197  * 0 if there isn't; or a negative errno.
198  */
199 static int
xfs_defer_create_intent(struct xfs_trans * tp,struct xfs_defer_pending * dfp,bool sort)200 xfs_defer_create_intent(
201 	struct xfs_trans		*tp,
202 	struct xfs_defer_pending	*dfp,
203 	bool				sort)
204 {
205 	const struct xfs_defer_op_type	*ops = defer_op_types[dfp->dfp_type];
206 	struct xfs_log_item		*lip;
207 
208 	if (dfp->dfp_intent)
209 		return 1;
210 
211 	lip = ops->create_intent(tp, &dfp->dfp_work, dfp->dfp_count, sort);
212 	if (!lip)
213 		return 0;
214 	if (IS_ERR(lip))
215 		return PTR_ERR(lip);
216 
217 	dfp->dfp_intent = lip;
218 	return 1;
219 }
220 
221 /*
222  * For each pending item in the intake list, log its intent item and the
223  * associated extents, then add the entire intake list to the end of
224  * the pending list.
225  *
226  * Returns 1 if at least one log item was associated with the deferred work;
227  * 0 if there are no log items; or a negative errno.
228  */
229 static int
xfs_defer_create_intents(struct xfs_trans * tp)230 xfs_defer_create_intents(
231 	struct xfs_trans		*tp)
232 {
233 	struct xfs_defer_pending	*dfp;
234 	int				ret = 0;
235 
236 	list_for_each_entry(dfp, &tp->t_dfops, dfp_list) {
237 		int			ret2;
238 
239 		trace_xfs_defer_create_intent(tp->t_mountp, dfp);
240 		ret2 = xfs_defer_create_intent(tp, dfp, true);
241 		if (ret2 < 0)
242 			return ret2;
243 		ret |= ret2;
244 	}
245 	return ret;
246 }
247 
248 STATIC void
xfs_defer_pending_abort(struct xfs_mount * mp,struct list_head * dop_list)249 xfs_defer_pending_abort(
250 	struct xfs_mount		*mp,
251 	struct list_head		*dop_list)
252 {
253 	struct xfs_defer_pending	*dfp;
254 	const struct xfs_defer_op_type	*ops;
255 
256 	/* Abort intent items that don't have a done item. */
257 	list_for_each_entry(dfp, dop_list, dfp_list) {
258 		ops = defer_op_types[dfp->dfp_type];
259 		trace_xfs_defer_pending_abort(mp, dfp);
260 		if (dfp->dfp_intent && !dfp->dfp_done) {
261 			ops->abort_intent(dfp->dfp_intent);
262 			dfp->dfp_intent = NULL;
263 		}
264 	}
265 }
266 
267 /* Abort all the intents that were committed. */
268 STATIC void
xfs_defer_trans_abort(struct xfs_trans * tp,struct list_head * dop_pending)269 xfs_defer_trans_abort(
270 	struct xfs_trans		*tp,
271 	struct list_head		*dop_pending)
272 {
273 	trace_xfs_defer_trans_abort(tp, _RET_IP_);
274 	xfs_defer_pending_abort(tp->t_mountp, dop_pending);
275 }
276 
277 /*
278  * Capture resources that the caller said not to release ("held") when the
279  * transaction commits.  Caller is responsible for zero-initializing @dres.
280  */
281 static int
xfs_defer_save_resources(struct xfs_defer_resources * dres,struct xfs_trans * tp)282 xfs_defer_save_resources(
283 	struct xfs_defer_resources	*dres,
284 	struct xfs_trans		*tp)
285 {
286 	struct xfs_buf_log_item		*bli;
287 	struct xfs_inode_log_item	*ili;
288 	struct xfs_log_item		*lip;
289 
290 	BUILD_BUG_ON(NBBY * sizeof(dres->dr_ordered) < XFS_DEFER_OPS_NR_BUFS);
291 
292 	list_for_each_entry(lip, &tp->t_items, li_trans) {
293 		switch (lip->li_type) {
294 		case XFS_LI_BUF:
295 			bli = container_of(lip, struct xfs_buf_log_item,
296 					   bli_item);
297 			if (bli->bli_flags & XFS_BLI_HOLD) {
298 				if (dres->dr_bufs >= XFS_DEFER_OPS_NR_BUFS) {
299 					ASSERT(0);
300 					return -EFSCORRUPTED;
301 				}
302 				if (bli->bli_flags & XFS_BLI_ORDERED)
303 					dres->dr_ordered |=
304 							(1U << dres->dr_bufs);
305 				else
306 					xfs_trans_dirty_buf(tp, bli->bli_buf);
307 				dres->dr_bp[dres->dr_bufs++] = bli->bli_buf;
308 			}
309 			break;
310 		case XFS_LI_INODE:
311 			ili = container_of(lip, struct xfs_inode_log_item,
312 					   ili_item);
313 			if (ili->ili_lock_flags == 0) {
314 				if (dres->dr_inos >= XFS_DEFER_OPS_NR_INODES) {
315 					ASSERT(0);
316 					return -EFSCORRUPTED;
317 				}
318 				xfs_trans_log_inode(tp, ili->ili_inode,
319 						    XFS_ILOG_CORE);
320 				dres->dr_ip[dres->dr_inos++] = ili->ili_inode;
321 			}
322 			break;
323 		default:
324 			break;
325 		}
326 	}
327 
328 	return 0;
329 }
330 
331 /* Attach the held resources to the transaction. */
332 static void
xfs_defer_restore_resources(struct xfs_trans * tp,struct xfs_defer_resources * dres)333 xfs_defer_restore_resources(
334 	struct xfs_trans		*tp,
335 	struct xfs_defer_resources	*dres)
336 {
337 	unsigned short			i;
338 
339 	/* Rejoin the joined inodes. */
340 	for (i = 0; i < dres->dr_inos; i++)
341 		xfs_trans_ijoin(tp, dres->dr_ip[i], 0);
342 
343 	/* Rejoin the buffers and dirty them so the log moves forward. */
344 	for (i = 0; i < dres->dr_bufs; i++) {
345 		xfs_trans_bjoin(tp, dres->dr_bp[i]);
346 		if (dres->dr_ordered & (1U << i))
347 			xfs_trans_ordered_buf(tp, dres->dr_bp[i]);
348 		xfs_trans_bhold(tp, dres->dr_bp[i]);
349 	}
350 }
351 
352 /* Roll a transaction so we can do some deferred op processing. */
353 STATIC int
xfs_defer_trans_roll(struct xfs_trans ** tpp)354 xfs_defer_trans_roll(
355 	struct xfs_trans		**tpp)
356 {
357 	struct xfs_defer_resources	dres = { };
358 	int				error;
359 
360 	error = xfs_defer_save_resources(&dres, *tpp);
361 	if (error)
362 		return error;
363 
364 	trace_xfs_defer_trans_roll(*tpp, _RET_IP_);
365 
366 	/*
367 	 * Roll the transaction.  Rolling always given a new transaction (even
368 	 * if committing the old one fails!) to hand back to the caller, so we
369 	 * join the held resources to the new transaction so that we always
370 	 * return with the held resources joined to @tpp, no matter what
371 	 * happened.
372 	 */
373 	error = xfs_trans_roll(tpp);
374 
375 	xfs_defer_restore_resources(*tpp, &dres);
376 
377 	if (error)
378 		trace_xfs_defer_trans_roll_error(*tpp, error);
379 	return error;
380 }
381 
382 /*
383  * Free up any items left in the list.
384  */
385 static void
xfs_defer_cancel_list(struct xfs_mount * mp,struct list_head * dop_list)386 xfs_defer_cancel_list(
387 	struct xfs_mount		*mp,
388 	struct list_head		*dop_list)
389 {
390 	struct xfs_defer_pending	*dfp;
391 	struct xfs_defer_pending	*pli;
392 	struct list_head		*pwi;
393 	struct list_head		*n;
394 	const struct xfs_defer_op_type	*ops;
395 
396 	/*
397 	 * Free the pending items.  Caller should already have arranged
398 	 * for the intent items to be released.
399 	 */
400 	list_for_each_entry_safe(dfp, pli, dop_list, dfp_list) {
401 		ops = defer_op_types[dfp->dfp_type];
402 		trace_xfs_defer_cancel_list(mp, dfp);
403 		list_del(&dfp->dfp_list);
404 		list_for_each_safe(pwi, n, &dfp->dfp_work) {
405 			list_del(pwi);
406 			dfp->dfp_count--;
407 			trace_xfs_defer_cancel_item(mp, dfp, pwi);
408 			ops->cancel_item(pwi);
409 		}
410 		ASSERT(dfp->dfp_count == 0);
411 		kmem_cache_free(xfs_defer_pending_cache, dfp);
412 	}
413 }
414 
415 /*
416  * Prevent a log intent item from pinning the tail of the log by logging a
417  * done item to release the intent item; and then log a new intent item.
418  * The caller should provide a fresh transaction and roll it after we're done.
419  */
420 static int
xfs_defer_relog(struct xfs_trans ** tpp,struct list_head * dfops)421 xfs_defer_relog(
422 	struct xfs_trans		**tpp,
423 	struct list_head		*dfops)
424 {
425 	struct xlog			*log = (*tpp)->t_mountp->m_log;
426 	struct xfs_defer_pending	*dfp;
427 	xfs_lsn_t			threshold_lsn = NULLCOMMITLSN;
428 
429 
430 	ASSERT((*tpp)->t_flags & XFS_TRANS_PERM_LOG_RES);
431 
432 	list_for_each_entry(dfp, dfops, dfp_list) {
433 		/*
434 		 * If the log intent item for this deferred op is not a part of
435 		 * the current log checkpoint, relog the intent item to keep
436 		 * the log tail moving forward.  We're ok with this being racy
437 		 * because an incorrect decision means we'll be a little slower
438 		 * at pushing the tail.
439 		 */
440 		if (dfp->dfp_intent == NULL ||
441 		    xfs_log_item_in_current_chkpt(dfp->dfp_intent))
442 			continue;
443 
444 		/*
445 		 * Figure out where we need the tail to be in order to maintain
446 		 * the minimum required free space in the log.  Only sample
447 		 * the log threshold once per call.
448 		 */
449 		if (threshold_lsn == NULLCOMMITLSN) {
450 			threshold_lsn = xlog_grant_push_threshold(log, 0);
451 			if (threshold_lsn == NULLCOMMITLSN)
452 				break;
453 		}
454 		if (XFS_LSN_CMP(dfp->dfp_intent->li_lsn, threshold_lsn) >= 0)
455 			continue;
456 
457 		trace_xfs_defer_relog_intent((*tpp)->t_mountp, dfp);
458 		XFS_STATS_INC((*tpp)->t_mountp, defer_relog);
459 		dfp->dfp_intent = xfs_trans_item_relog(dfp->dfp_intent, *tpp);
460 	}
461 
462 	if ((*tpp)->t_flags & XFS_TRANS_DIRTY)
463 		return xfs_defer_trans_roll(tpp);
464 	return 0;
465 }
466 
467 /*
468  * Log an intent-done item for the first pending intent, and finish the work
469  * items.
470  */
471 static int
xfs_defer_finish_one(struct xfs_trans * tp,struct xfs_defer_pending * dfp)472 xfs_defer_finish_one(
473 	struct xfs_trans		*tp,
474 	struct xfs_defer_pending	*dfp)
475 {
476 	const struct xfs_defer_op_type	*ops = defer_op_types[dfp->dfp_type];
477 	struct xfs_btree_cur		*state = NULL;
478 	struct list_head		*li, *n;
479 	int				error;
480 
481 	trace_xfs_defer_pending_finish(tp->t_mountp, dfp);
482 
483 	dfp->dfp_done = ops->create_done(tp, dfp->dfp_intent, dfp->dfp_count);
484 	list_for_each_safe(li, n, &dfp->dfp_work) {
485 		list_del(li);
486 		dfp->dfp_count--;
487 		trace_xfs_defer_finish_item(tp->t_mountp, dfp, li);
488 		error = ops->finish_item(tp, dfp->dfp_done, li, &state);
489 		if (error == -EAGAIN) {
490 			int		ret;
491 
492 			/*
493 			 * Caller wants a fresh transaction; put the work item
494 			 * back on the list and log a new log intent item to
495 			 * replace the old one.  See "Requesting a Fresh
496 			 * Transaction while Finishing Deferred Work" above.
497 			 */
498 			list_add(li, &dfp->dfp_work);
499 			dfp->dfp_count++;
500 			dfp->dfp_done = NULL;
501 			dfp->dfp_intent = NULL;
502 			ret = xfs_defer_create_intent(tp, dfp, false);
503 			if (ret < 0)
504 				error = ret;
505 		}
506 
507 		if (error)
508 			goto out;
509 	}
510 
511 	/* Done with the dfp, free it. */
512 	list_del(&dfp->dfp_list);
513 	kmem_cache_free(xfs_defer_pending_cache, dfp);
514 out:
515 	if (ops->finish_cleanup)
516 		ops->finish_cleanup(tp, state, error);
517 	return error;
518 }
519 
520 /*
521  * Finish all the pending work.  This involves logging intent items for
522  * any work items that wandered in since the last transaction roll (if
523  * one has even happened), rolling the transaction, and finishing the
524  * work items in the first item on the logged-and-pending list.
525  *
526  * If an inode is provided, relog it to the new transaction.
527  */
528 int
xfs_defer_finish_noroll(struct xfs_trans ** tp)529 xfs_defer_finish_noroll(
530 	struct xfs_trans		**tp)
531 {
532 	struct xfs_defer_pending	*dfp = NULL;
533 	int				error = 0;
534 	LIST_HEAD(dop_pending);
535 
536 	ASSERT((*tp)->t_flags & XFS_TRANS_PERM_LOG_RES);
537 
538 	trace_xfs_defer_finish(*tp, _RET_IP_);
539 
540 	/* Until we run out of pending work to finish... */
541 	while (!list_empty(&dop_pending) || !list_empty(&(*tp)->t_dfops)) {
542 		/*
543 		 * Deferred items that are created in the process of finishing
544 		 * other deferred work items should be queued at the head of
545 		 * the pending list, which puts them ahead of the deferred work
546 		 * that was created by the caller.  This keeps the number of
547 		 * pending work items to a minimum, which decreases the amount
548 		 * of time that any one intent item can stick around in memory,
549 		 * pinning the log tail.
550 		 */
551 		int has_intents = xfs_defer_create_intents(*tp);
552 
553 		list_splice_init(&(*tp)->t_dfops, &dop_pending);
554 
555 		if (has_intents < 0) {
556 			error = has_intents;
557 			goto out_shutdown;
558 		}
559 		if (has_intents || dfp) {
560 			error = xfs_defer_trans_roll(tp);
561 			if (error)
562 				goto out_shutdown;
563 
564 			/* Relog intent items to keep the log moving. */
565 			error = xfs_defer_relog(tp, &dop_pending);
566 			if (error)
567 				goto out_shutdown;
568 		}
569 
570 		dfp = list_first_entry(&dop_pending, struct xfs_defer_pending,
571 				       dfp_list);
572 		error = xfs_defer_finish_one(*tp, dfp);
573 		if (error && error != -EAGAIN)
574 			goto out_shutdown;
575 	}
576 
577 	trace_xfs_defer_finish_done(*tp, _RET_IP_);
578 	return 0;
579 
580 out_shutdown:
581 	xfs_defer_trans_abort(*tp, &dop_pending);
582 	xfs_force_shutdown((*tp)->t_mountp, SHUTDOWN_CORRUPT_INCORE);
583 	trace_xfs_defer_finish_error(*tp, error);
584 	xfs_defer_cancel_list((*tp)->t_mountp, &dop_pending);
585 	xfs_defer_cancel(*tp);
586 	return error;
587 }
588 
589 int
xfs_defer_finish(struct xfs_trans ** tp)590 xfs_defer_finish(
591 	struct xfs_trans	**tp)
592 {
593 	int			error;
594 
595 	/*
596 	 * Finish and roll the transaction once more to avoid returning to the
597 	 * caller with a dirty transaction.
598 	 */
599 	error = xfs_defer_finish_noroll(tp);
600 	if (error)
601 		return error;
602 	if ((*tp)->t_flags & XFS_TRANS_DIRTY) {
603 		error = xfs_defer_trans_roll(tp);
604 		if (error) {
605 			xfs_force_shutdown((*tp)->t_mountp,
606 					   SHUTDOWN_CORRUPT_INCORE);
607 			return error;
608 		}
609 	}
610 
611 	/* Reset LOWMODE now that we've finished all the dfops. */
612 	ASSERT(list_empty(&(*tp)->t_dfops));
613 	(*tp)->t_flags &= ~XFS_TRANS_LOWMODE;
614 	return 0;
615 }
616 
617 void
xfs_defer_cancel(struct xfs_trans * tp)618 xfs_defer_cancel(
619 	struct xfs_trans	*tp)
620 {
621 	struct xfs_mount	*mp = tp->t_mountp;
622 
623 	trace_xfs_defer_cancel(tp, _RET_IP_);
624 	xfs_defer_cancel_list(mp, &tp->t_dfops);
625 }
626 
627 /* Add an item for later deferred processing. */
628 void
xfs_defer_add(struct xfs_trans * tp,enum xfs_defer_ops_type type,struct list_head * li)629 xfs_defer_add(
630 	struct xfs_trans		*tp,
631 	enum xfs_defer_ops_type		type,
632 	struct list_head		*li)
633 {
634 	struct xfs_defer_pending	*dfp = NULL;
635 	const struct xfs_defer_op_type	*ops = defer_op_types[type];
636 
637 	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
638 	BUILD_BUG_ON(ARRAY_SIZE(defer_op_types) != XFS_DEFER_OPS_TYPE_MAX);
639 
640 	/*
641 	 * Add the item to a pending item at the end of the intake list.
642 	 * If the last pending item has the same type, reuse it.  Else,
643 	 * create a new pending item at the end of the intake list.
644 	 */
645 	if (!list_empty(&tp->t_dfops)) {
646 		dfp = list_last_entry(&tp->t_dfops,
647 				struct xfs_defer_pending, dfp_list);
648 		if (dfp->dfp_type != type ||
649 		    (ops->max_items && dfp->dfp_count >= ops->max_items))
650 			dfp = NULL;
651 	}
652 	if (!dfp) {
653 		dfp = kmem_cache_zalloc(xfs_defer_pending_cache,
654 				GFP_NOFS | __GFP_NOFAIL);
655 		dfp->dfp_type = type;
656 		dfp->dfp_intent = NULL;
657 		dfp->dfp_done = NULL;
658 		dfp->dfp_count = 0;
659 		INIT_LIST_HEAD(&dfp->dfp_work);
660 		list_add_tail(&dfp->dfp_list, &tp->t_dfops);
661 	}
662 
663 	list_add_tail(li, &dfp->dfp_work);
664 	trace_xfs_defer_add_item(tp->t_mountp, dfp, li);
665 	dfp->dfp_count++;
666 }
667 
668 /*
669  * Move deferred ops from one transaction to another and reset the source to
670  * initial state. This is primarily used to carry state forward across
671  * transaction rolls with pending dfops.
672  */
673 void
xfs_defer_move(struct xfs_trans * dtp,struct xfs_trans * stp)674 xfs_defer_move(
675 	struct xfs_trans	*dtp,
676 	struct xfs_trans	*stp)
677 {
678 	list_splice_init(&stp->t_dfops, &dtp->t_dfops);
679 
680 	/*
681 	 * Low free space mode was historically controlled by a dfops field.
682 	 * This meant that low mode state potentially carried across multiple
683 	 * transaction rolls. Transfer low mode on a dfops move to preserve
684 	 * that behavior.
685 	 */
686 	dtp->t_flags |= (stp->t_flags & XFS_TRANS_LOWMODE);
687 	stp->t_flags &= ~XFS_TRANS_LOWMODE;
688 }
689 
690 /*
691  * Prepare a chain of fresh deferred ops work items to be completed later.  Log
692  * recovery requires the ability to put off until later the actual finishing
693  * work so that it can process unfinished items recovered from the log in
694  * correct order.
695  *
696  * Create and log intent items for all the work that we're capturing so that we
697  * can be assured that the items will get replayed if the system goes down
698  * before log recovery gets a chance to finish the work it put off.  The entire
699  * deferred ops state is transferred to the capture structure and the
700  * transaction is then ready for the caller to commit it.  If there are no
701  * intent items to capture, this function returns NULL.
702  *
703  * If capture_ip is not NULL, the capture structure will obtain an extra
704  * reference to the inode.
705  */
706 static struct xfs_defer_capture *
xfs_defer_ops_capture(struct xfs_trans * tp)707 xfs_defer_ops_capture(
708 	struct xfs_trans		*tp)
709 {
710 	struct xfs_defer_capture	*dfc;
711 	unsigned short			i;
712 	int				error;
713 
714 	if (list_empty(&tp->t_dfops))
715 		return NULL;
716 
717 	error = xfs_defer_create_intents(tp);
718 	if (error < 0)
719 		return ERR_PTR(error);
720 
721 	/* Create an object to capture the defer ops. */
722 	dfc = kmem_zalloc(sizeof(*dfc), KM_NOFS);
723 	INIT_LIST_HEAD(&dfc->dfc_list);
724 	INIT_LIST_HEAD(&dfc->dfc_dfops);
725 
726 	/* Move the dfops chain and transaction state to the capture struct. */
727 	list_splice_init(&tp->t_dfops, &dfc->dfc_dfops);
728 	dfc->dfc_tpflags = tp->t_flags & XFS_TRANS_LOWMODE;
729 	tp->t_flags &= ~XFS_TRANS_LOWMODE;
730 
731 	/* Capture the remaining block reservations along with the dfops. */
732 	dfc->dfc_blkres = tp->t_blk_res - tp->t_blk_res_used;
733 	dfc->dfc_rtxres = tp->t_rtx_res - tp->t_rtx_res_used;
734 
735 	/* Preserve the log reservation size. */
736 	dfc->dfc_logres = tp->t_log_res;
737 
738 	error = xfs_defer_save_resources(&dfc->dfc_held, tp);
739 	if (error) {
740 		/*
741 		 * Resource capture should never fail, but if it does, we
742 		 * still have to shut down the log and release things
743 		 * properly.
744 		 */
745 		xfs_force_shutdown(tp->t_mountp, SHUTDOWN_CORRUPT_INCORE);
746 	}
747 
748 	/*
749 	 * Grab extra references to the inodes and buffers because callers are
750 	 * expected to release their held references after we commit the
751 	 * transaction.
752 	 */
753 	for (i = 0; i < dfc->dfc_held.dr_inos; i++) {
754 		ASSERT(xfs_isilocked(dfc->dfc_held.dr_ip[i], XFS_ILOCK_EXCL));
755 		ihold(VFS_I(dfc->dfc_held.dr_ip[i]));
756 	}
757 
758 	for (i = 0; i < dfc->dfc_held.dr_bufs; i++)
759 		xfs_buf_hold(dfc->dfc_held.dr_bp[i]);
760 
761 	return dfc;
762 }
763 
764 /* Release all resources that we used to capture deferred ops. */
765 void
xfs_defer_ops_capture_abort(struct xfs_mount * mp,struct xfs_defer_capture * dfc)766 xfs_defer_ops_capture_abort(
767 	struct xfs_mount		*mp,
768 	struct xfs_defer_capture	*dfc)
769 {
770 	unsigned short			i;
771 
772 	xfs_defer_pending_abort(mp, &dfc->dfc_dfops);
773 	xfs_defer_cancel_list(mp, &dfc->dfc_dfops);
774 
775 	for (i = 0; i < dfc->dfc_held.dr_bufs; i++)
776 		xfs_buf_relse(dfc->dfc_held.dr_bp[i]);
777 
778 	for (i = 0; i < dfc->dfc_held.dr_inos; i++)
779 		xfs_irele(dfc->dfc_held.dr_ip[i]);
780 
781 	kmem_free(dfc);
782 }
783 
784 /*
785  * Capture any deferred ops and commit the transaction.  This is the last step
786  * needed to finish a log intent item that we recovered from the log.  If any
787  * of the deferred ops operate on an inode, the caller must pass in that inode
788  * so that the reference can be transferred to the capture structure.  The
789  * caller must hold ILOCK_EXCL on the inode, and must unlock it before calling
790  * xfs_defer_ops_continue.
791  */
792 int
xfs_defer_ops_capture_and_commit(struct xfs_trans * tp,struct list_head * capture_list)793 xfs_defer_ops_capture_and_commit(
794 	struct xfs_trans		*tp,
795 	struct list_head		*capture_list)
796 {
797 	struct xfs_mount		*mp = tp->t_mountp;
798 	struct xfs_defer_capture	*dfc;
799 	int				error;
800 
801 	/* If we don't capture anything, commit transaction and exit. */
802 	dfc = xfs_defer_ops_capture(tp);
803 	if (IS_ERR(dfc)) {
804 		xfs_trans_cancel(tp);
805 		return PTR_ERR(dfc);
806 	}
807 	if (!dfc)
808 		return xfs_trans_commit(tp);
809 
810 	/* Commit the transaction and add the capture structure to the list. */
811 	error = xfs_trans_commit(tp);
812 	if (error) {
813 		xfs_defer_ops_capture_abort(mp, dfc);
814 		return error;
815 	}
816 
817 	list_add_tail(&dfc->dfc_list, capture_list);
818 	return 0;
819 }
820 
821 /*
822  * Attach a chain of captured deferred ops to a new transaction and free the
823  * capture structure.  If an inode was captured, it will be passed back to the
824  * caller with ILOCK_EXCL held and joined to the transaction with lockflags==0.
825  * The caller now owns the inode reference.
826  */
827 void
xfs_defer_ops_continue(struct xfs_defer_capture * dfc,struct xfs_trans * tp,struct xfs_defer_resources * dres)828 xfs_defer_ops_continue(
829 	struct xfs_defer_capture	*dfc,
830 	struct xfs_trans		*tp,
831 	struct xfs_defer_resources	*dres)
832 {
833 	unsigned int			i;
834 
835 	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
836 	ASSERT(!(tp->t_flags & XFS_TRANS_DIRTY));
837 
838 	/* Lock the captured resources to the new transaction. */
839 	if (dfc->dfc_held.dr_inos == 2)
840 		xfs_lock_two_inodes(dfc->dfc_held.dr_ip[0], XFS_ILOCK_EXCL,
841 				    dfc->dfc_held.dr_ip[1], XFS_ILOCK_EXCL);
842 	else if (dfc->dfc_held.dr_inos == 1)
843 		xfs_ilock(dfc->dfc_held.dr_ip[0], XFS_ILOCK_EXCL);
844 
845 	for (i = 0; i < dfc->dfc_held.dr_bufs; i++)
846 		xfs_buf_lock(dfc->dfc_held.dr_bp[i]);
847 
848 	/* Join the captured resources to the new transaction. */
849 	xfs_defer_restore_resources(tp, &dfc->dfc_held);
850 	memcpy(dres, &dfc->dfc_held, sizeof(struct xfs_defer_resources));
851 	dres->dr_bufs = 0;
852 
853 	/* Move captured dfops chain and state to the transaction. */
854 	list_splice_init(&dfc->dfc_dfops, &tp->t_dfops);
855 	tp->t_flags |= dfc->dfc_tpflags;
856 
857 	kmem_free(dfc);
858 }
859 
860 /* Release the resources captured and continued during recovery. */
861 void
xfs_defer_resources_rele(struct xfs_defer_resources * dres)862 xfs_defer_resources_rele(
863 	struct xfs_defer_resources	*dres)
864 {
865 	unsigned short			i;
866 
867 	for (i = 0; i < dres->dr_inos; i++) {
868 		xfs_iunlock(dres->dr_ip[i], XFS_ILOCK_EXCL);
869 		xfs_irele(dres->dr_ip[i]);
870 		dres->dr_ip[i] = NULL;
871 	}
872 
873 	for (i = 0; i < dres->dr_bufs; i++) {
874 		xfs_buf_relse(dres->dr_bp[i]);
875 		dres->dr_bp[i] = NULL;
876 	}
877 
878 	dres->dr_inos = 0;
879 	dres->dr_bufs = 0;
880 	dres->dr_ordered = 0;
881 }
882 
883 static inline int __init
xfs_defer_init_cache(void)884 xfs_defer_init_cache(void)
885 {
886 	xfs_defer_pending_cache = kmem_cache_create("xfs_defer_pending",
887 			sizeof(struct xfs_defer_pending),
888 			0, 0, NULL);
889 
890 	return xfs_defer_pending_cache != NULL ? 0 : -ENOMEM;
891 }
892 
893 static inline void
xfs_defer_destroy_cache(void)894 xfs_defer_destroy_cache(void)
895 {
896 	kmem_cache_destroy(xfs_defer_pending_cache);
897 	xfs_defer_pending_cache = NULL;
898 }
899 
900 /* Set up caches for deferred work items. */
901 int __init
xfs_defer_init_item_caches(void)902 xfs_defer_init_item_caches(void)
903 {
904 	int				error;
905 
906 	error = xfs_defer_init_cache();
907 	if (error)
908 		return error;
909 	error = xfs_rmap_intent_init_cache();
910 	if (error)
911 		goto err;
912 	error = xfs_refcount_intent_init_cache();
913 	if (error)
914 		goto err;
915 	error = xfs_bmap_intent_init_cache();
916 	if (error)
917 		goto err;
918 	error = xfs_extfree_intent_init_cache();
919 	if (error)
920 		goto err;
921 	error = xfs_attr_intent_init_cache();
922 	if (error)
923 		goto err;
924 	return 0;
925 err:
926 	xfs_defer_destroy_item_caches();
927 	return error;
928 }
929 
930 /* Destroy all the deferred work item caches, if they've been allocated. */
931 void
xfs_defer_destroy_item_caches(void)932 xfs_defer_destroy_item_caches(void)
933 {
934 	xfs_attr_intent_destroy_cache();
935 	xfs_extfree_intent_destroy_cache();
936 	xfs_bmap_intent_destroy_cache();
937 	xfs_refcount_intent_destroy_cache();
938 	xfs_rmap_intent_destroy_cache();
939 	xfs_defer_destroy_cache();
940 }
941