hyperv: Add processing of MTU reduced by the host
[linux/fpc-iii.git] / fs / xfs / xfs_log_cil.c
blobf506c457011eb1970128fa637dce35500d2a4b54
1 /*
2 * Copyright (c) 2010 Red Hat, Inc. All Rights Reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation.
8 * This program is distributed in the hope that it would be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write the Free Software Foundation,
15 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 #include "xfs.h"
19 #include "xfs_fs.h"
20 #include "xfs_log_format.h"
21 #include "xfs_shared.h"
22 #include "xfs_trans_resv.h"
23 #include "xfs_sb.h"
24 #include "xfs_ag.h"
25 #include "xfs_mount.h"
26 #include "xfs_error.h"
27 #include "xfs_alloc.h"
28 #include "xfs_extent_busy.h"
29 #include "xfs_discard.h"
30 #include "xfs_trans.h"
31 #include "xfs_trans_priv.h"
32 #include "xfs_log.h"
33 #include "xfs_log_priv.h"
36 * Allocate a new ticket. Failing to get a new ticket makes it really hard to
37 * recover, so we don't allow failure here. Also, we allocate in a context that
38 * we don't want to be issuing transactions from, so we need to tell the
39 * allocation code this as well.
41 * We don't reserve any space for the ticket - we are going to steal whatever
42 * space we require from transactions as they commit. To ensure we reserve all
43 * the space required, we need to set the current reservation of the ticket to
44 * zero so that we know to steal the initial transaction overhead from the
45 * first transaction commit.
47 static struct xlog_ticket *
48 xlog_cil_ticket_alloc(
49 struct xlog *log)
51 struct xlog_ticket *tic;
53 tic = xlog_ticket_alloc(log, 0, 1, XFS_TRANSACTION, 0,
54 KM_SLEEP|KM_NOFS);
55 tic->t_trans_type = XFS_TRANS_CHECKPOINT;
58 * set the current reservation to zero so we know to steal the basic
59 * transaction overhead reservation from the first transaction commit.
61 tic->t_curr_res = 0;
62 return tic;
66 * After the first stage of log recovery is done, we know where the head and
67 * tail of the log are. We need this log initialisation done before we can
68 * initialise the first CIL checkpoint context.
70 * Here we allocate a log ticket to track space usage during a CIL push. This
71 * ticket is passed to xlog_write() directly so that we don't slowly leak log
72 * space by failing to account for space used by log headers and additional
73 * region headers for split regions.
75 void
76 xlog_cil_init_post_recovery(
77 struct xlog *log)
79 log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log);
80 log->l_cilp->xc_ctx->sequence = 1;
84 * Prepare the log item for insertion into the CIL. Calculate the difference in
85 * log space and vectors it will consume, and if it is a new item pin it as
86 * well.
88 STATIC void
89 xfs_cil_prepare_item(
90 struct xlog *log,
91 struct xfs_log_vec *lv,
92 struct xfs_log_vec *old_lv,
93 int *diff_len,
94 int *diff_iovecs)
96 /* Account for the new LV being passed in */
97 if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED) {
98 *diff_len += lv->lv_bytes;
99 *diff_iovecs += lv->lv_niovecs;
103 * If there is no old LV, this is the first time we've seen the item in
104 * this CIL context and so we need to pin it. If we are replacing the
105 * old_lv, then remove the space it accounts for and free it.
107 if (!old_lv)
108 lv->lv_item->li_ops->iop_pin(lv->lv_item);
109 else if (old_lv != lv) {
110 ASSERT(lv->lv_buf_len != XFS_LOG_VEC_ORDERED);
112 *diff_len -= old_lv->lv_bytes;
113 *diff_iovecs -= old_lv->lv_niovecs;
114 kmem_free(old_lv);
117 /* attach new log vector to log item */
118 lv->lv_item->li_lv = lv;
121 * If this is the first time the item is being committed to the
122 * CIL, store the sequence number on the log item so we can
123 * tell in future commits whether this is the first checkpoint
124 * the item is being committed into.
126 if (!lv->lv_item->li_seq)
127 lv->lv_item->li_seq = log->l_cilp->xc_ctx->sequence;
131 * Format log item into a flat buffers
133 * For delayed logging, we need to hold a formatted buffer containing all the
134 * changes on the log item. This enables us to relog the item in memory and
135 * write it out asynchronously without needing to relock the object that was
136 * modified at the time it gets written into the iclog.
138 * This function builds a vector for the changes in each log item in the
139 * transaction. It then works out the length of the buffer needed for each log
140 * item, allocates them and formats the vector for the item into the buffer.
141 * The buffer is then attached to the log item are then inserted into the
142 * Committed Item List for tracking until the next checkpoint is written out.
144 * We don't set up region headers during this process; we simply copy the
145 * regions into the flat buffer. We can do this because we still have to do a
146 * formatting step to write the regions into the iclog buffer. Writing the
147 * ophdrs during the iclog write means that we can support splitting large
148 * regions across iclog boundares without needing a change in the format of the
149 * item/region encapsulation.
151 * Hence what we need to do now is change the rewrite the vector array to point
152 * to the copied region inside the buffer we just allocated. This allows us to
153 * format the regions into the iclog as though they are being formatted
154 * directly out of the objects themselves.
156 static void
157 xlog_cil_insert_format_items(
158 struct xlog *log,
159 struct xfs_trans *tp,
160 int *diff_len,
161 int *diff_iovecs)
163 struct xfs_log_item_desc *lidp;
166 /* Bail out if we didn't find a log item. */
167 if (list_empty(&tp->t_items)) {
168 ASSERT(0);
169 return;
172 list_for_each_entry(lidp, &tp->t_items, lid_trans) {
173 struct xfs_log_item *lip = lidp->lid_item;
174 struct xfs_log_vec *lv;
175 struct xfs_log_vec *old_lv;
176 int niovecs = 0;
177 int nbytes = 0;
178 int buf_size;
179 bool ordered = false;
181 /* Skip items which aren't dirty in this transaction. */
182 if (!(lidp->lid_flags & XFS_LID_DIRTY))
183 continue;
185 /* get number of vecs and size of data to be stored */
186 lip->li_ops->iop_size(lip, &niovecs, &nbytes);
188 /* Skip items that do not have any vectors for writing */
189 if (!niovecs)
190 continue;
193 * Ordered items need to be tracked but we do not wish to write
194 * them. We need a logvec to track the object, but we do not
195 * need an iovec or buffer to be allocated for copying data.
197 if (niovecs == XFS_LOG_VEC_ORDERED) {
198 ordered = true;
199 niovecs = 0;
200 nbytes = 0;
204 * We 64-bit align the length of each iovec so that the start
205 * of the next one is naturally aligned. We'll need to
206 * account for that slack space here. Then round nbytes up
207 * to 64-bit alignment so that the initial buffer alignment is
208 * easy to calculate and verify.
210 nbytes += niovecs * sizeof(uint64_t);
211 nbytes = round_up(nbytes, sizeof(uint64_t));
213 /* grab the old item if it exists for reservation accounting */
214 old_lv = lip->li_lv;
217 * The data buffer needs to start 64-bit aligned, so round up
218 * that space to ensure we can align it appropriately and not
219 * overrun the buffer.
221 buf_size = nbytes +
222 round_up((sizeof(struct xfs_log_vec) +
223 niovecs * sizeof(struct xfs_log_iovec)),
224 sizeof(uint64_t));
226 /* compare to existing item size */
227 if (lip->li_lv && buf_size <= lip->li_lv->lv_size) {
228 /* same or smaller, optimise common overwrite case */
229 lv = lip->li_lv;
230 lv->lv_next = NULL;
232 if (ordered)
233 goto insert;
236 * set the item up as though it is a new insertion so
237 * that the space reservation accounting is correct.
239 *diff_iovecs -= lv->lv_niovecs;
240 *diff_len -= lv->lv_bytes;
241 } else {
242 /* allocate new data chunk */
243 lv = kmem_zalloc(buf_size, KM_SLEEP|KM_NOFS);
244 lv->lv_item = lip;
245 lv->lv_size = buf_size;
246 if (ordered) {
247 /* track as an ordered logvec */
248 ASSERT(lip->li_lv == NULL);
249 lv->lv_buf_len = XFS_LOG_VEC_ORDERED;
250 goto insert;
252 lv->lv_iovecp = (struct xfs_log_iovec *)&lv[1];
255 /* Ensure the lv is set up according to ->iop_size */
256 lv->lv_niovecs = niovecs;
258 /* The allocated data region lies beyond the iovec region */
259 lv->lv_buf_len = 0;
260 lv->lv_bytes = 0;
261 lv->lv_buf = (char *)lv + buf_size - nbytes;
262 ASSERT(IS_ALIGNED((unsigned long)lv->lv_buf, sizeof(uint64_t)));
264 lip->li_ops->iop_format(lip, lv);
265 insert:
266 ASSERT(lv->lv_buf_len <= nbytes);
267 xfs_cil_prepare_item(log, lv, old_lv, diff_len, diff_iovecs);
272 * Insert the log items into the CIL and calculate the difference in space
273 * consumed by the item. Add the space to the checkpoint ticket and calculate
274 * if the change requires additional log metadata. If it does, take that space
275 * as well. Remove the amount of space we added to the checkpoint ticket from
276 * the current transaction ticket so that the accounting works out correctly.
278 static void
279 xlog_cil_insert_items(
280 struct xlog *log,
281 struct xfs_trans *tp)
283 struct xfs_cil *cil = log->l_cilp;
284 struct xfs_cil_ctx *ctx = cil->xc_ctx;
285 struct xfs_log_item_desc *lidp;
286 int len = 0;
287 int diff_iovecs = 0;
288 int iclog_space;
290 ASSERT(tp);
293 * We can do this safely because the context can't checkpoint until we
294 * are done so it doesn't matter exactly how we update the CIL.
296 xlog_cil_insert_format_items(log, tp, &len, &diff_iovecs);
299 * Now (re-)position everything modified at the tail of the CIL.
300 * We do this here so we only need to take the CIL lock once during
301 * the transaction commit.
303 spin_lock(&cil->xc_cil_lock);
304 list_for_each_entry(lidp, &tp->t_items, lid_trans) {
305 struct xfs_log_item *lip = lidp->lid_item;
307 /* Skip items which aren't dirty in this transaction. */
308 if (!(lidp->lid_flags & XFS_LID_DIRTY))
309 continue;
311 list_move_tail(&lip->li_cil, &cil->xc_cil);
314 /* account for space used by new iovec headers */
315 len += diff_iovecs * sizeof(xlog_op_header_t);
316 ctx->nvecs += diff_iovecs;
318 /* attach the transaction to the CIL if it has any busy extents */
319 if (!list_empty(&tp->t_busy))
320 list_splice_init(&tp->t_busy, &ctx->busy_extents);
323 * Now transfer enough transaction reservation to the context ticket
324 * for the checkpoint. The context ticket is special - the unit
325 * reservation has to grow as well as the current reservation as we
326 * steal from tickets so we can correctly determine the space used
327 * during the transaction commit.
329 if (ctx->ticket->t_curr_res == 0) {
330 ctx->ticket->t_curr_res = ctx->ticket->t_unit_res;
331 tp->t_ticket->t_curr_res -= ctx->ticket->t_unit_res;
334 /* do we need space for more log record headers? */
335 iclog_space = log->l_iclog_size - log->l_iclog_hsize;
336 if (len > 0 && (ctx->space_used / iclog_space !=
337 (ctx->space_used + len) / iclog_space)) {
338 int hdrs;
340 hdrs = (len + iclog_space - 1) / iclog_space;
341 /* need to take into account split region headers, too */
342 hdrs *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
343 ctx->ticket->t_unit_res += hdrs;
344 ctx->ticket->t_curr_res += hdrs;
345 tp->t_ticket->t_curr_res -= hdrs;
346 ASSERT(tp->t_ticket->t_curr_res >= len);
348 tp->t_ticket->t_curr_res -= len;
349 ctx->space_used += len;
351 spin_unlock(&cil->xc_cil_lock);
354 static void
355 xlog_cil_free_logvec(
356 struct xfs_log_vec *log_vector)
358 struct xfs_log_vec *lv;
360 for (lv = log_vector; lv; ) {
361 struct xfs_log_vec *next = lv->lv_next;
362 kmem_free(lv);
363 lv = next;
368 * Mark all items committed and clear busy extents. We free the log vector
369 * chains in a separate pass so that we unpin the log items as quickly as
370 * possible.
372 static void
373 xlog_cil_committed(
374 void *args,
375 int abort)
377 struct xfs_cil_ctx *ctx = args;
378 struct xfs_mount *mp = ctx->cil->xc_log->l_mp;
380 xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, ctx->lv_chain,
381 ctx->start_lsn, abort);
383 xfs_extent_busy_sort(&ctx->busy_extents);
384 xfs_extent_busy_clear(mp, &ctx->busy_extents,
385 (mp->m_flags & XFS_MOUNT_DISCARD) && !abort);
388 * If we are aborting the commit, wake up anyone waiting on the
389 * committing list. If we don't, then a shutdown we can leave processes
390 * waiting in xlog_cil_force_lsn() waiting on a sequence commit that
391 * will never happen because we aborted it.
393 spin_lock(&ctx->cil->xc_push_lock);
394 if (abort)
395 wake_up_all(&ctx->cil->xc_commit_wait);
396 list_del(&ctx->committing);
397 spin_unlock(&ctx->cil->xc_push_lock);
399 xlog_cil_free_logvec(ctx->lv_chain);
401 if (!list_empty(&ctx->busy_extents)) {
402 ASSERT(mp->m_flags & XFS_MOUNT_DISCARD);
404 xfs_discard_extents(mp, &ctx->busy_extents);
405 xfs_extent_busy_clear(mp, &ctx->busy_extents, false);
408 kmem_free(ctx);
412 * Push the Committed Item List to the log. If @push_seq flag is zero, then it
413 * is a background flush and so we can chose to ignore it. Otherwise, if the
414 * current sequence is the same as @push_seq we need to do a flush. If
415 * @push_seq is less than the current sequence, then it has already been
416 * flushed and we don't need to do anything - the caller will wait for it to
417 * complete if necessary.
419 * @push_seq is a value rather than a flag because that allows us to do an
420 * unlocked check of the sequence number for a match. Hence we can allows log
421 * forces to run racily and not issue pushes for the same sequence twice. If we
422 * get a race between multiple pushes for the same sequence they will block on
423 * the first one and then abort, hence avoiding needless pushes.
425 STATIC int
426 xlog_cil_push(
427 struct xlog *log)
429 struct xfs_cil *cil = log->l_cilp;
430 struct xfs_log_vec *lv;
431 struct xfs_cil_ctx *ctx;
432 struct xfs_cil_ctx *new_ctx;
433 struct xlog_in_core *commit_iclog;
434 struct xlog_ticket *tic;
435 int num_iovecs;
436 int error = 0;
437 struct xfs_trans_header thdr;
438 struct xfs_log_iovec lhdr;
439 struct xfs_log_vec lvhdr = { NULL };
440 xfs_lsn_t commit_lsn;
441 xfs_lsn_t push_seq;
443 if (!cil)
444 return 0;
446 new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS);
447 new_ctx->ticket = xlog_cil_ticket_alloc(log);
449 down_write(&cil->xc_ctx_lock);
450 ctx = cil->xc_ctx;
452 spin_lock(&cil->xc_push_lock);
453 push_seq = cil->xc_push_seq;
454 ASSERT(push_seq <= ctx->sequence);
457 * Check if we've anything to push. If there is nothing, then we don't
458 * move on to a new sequence number and so we have to be able to push
459 * this sequence again later.
461 if (list_empty(&cil->xc_cil)) {
462 cil->xc_push_seq = 0;
463 spin_unlock(&cil->xc_push_lock);
464 goto out_skip;
468 /* check for a previously pushed seqeunce */
469 if (push_seq < cil->xc_ctx->sequence) {
470 spin_unlock(&cil->xc_push_lock);
471 goto out_skip;
475 * We are now going to push this context, so add it to the committing
476 * list before we do anything else. This ensures that anyone waiting on
477 * this push can easily detect the difference between a "push in
478 * progress" and "CIL is empty, nothing to do".
480 * IOWs, a wait loop can now check for:
481 * the current sequence not being found on the committing list;
482 * an empty CIL; and
483 * an unchanged sequence number
484 * to detect a push that had nothing to do and therefore does not need
485 * waiting on. If the CIL is not empty, we get put on the committing
486 * list before emptying the CIL and bumping the sequence number. Hence
487 * an empty CIL and an unchanged sequence number means we jumped out
488 * above after doing nothing.
490 * Hence the waiter will either find the commit sequence on the
491 * committing list or the sequence number will be unchanged and the CIL
492 * still dirty. In that latter case, the push has not yet started, and
493 * so the waiter will have to continue trying to check the CIL
494 * committing list until it is found. In extreme cases of delay, the
495 * sequence may fully commit between the attempts the wait makes to wait
496 * on the commit sequence.
498 list_add(&ctx->committing, &cil->xc_committing);
499 spin_unlock(&cil->xc_push_lock);
502 * pull all the log vectors off the items in the CIL, and
503 * remove the items from the CIL. We don't need the CIL lock
504 * here because it's only needed on the transaction commit
505 * side which is currently locked out by the flush lock.
507 lv = NULL;
508 num_iovecs = 0;
509 while (!list_empty(&cil->xc_cil)) {
510 struct xfs_log_item *item;
512 item = list_first_entry(&cil->xc_cil,
513 struct xfs_log_item, li_cil);
514 list_del_init(&item->li_cil);
515 if (!ctx->lv_chain)
516 ctx->lv_chain = item->li_lv;
517 else
518 lv->lv_next = item->li_lv;
519 lv = item->li_lv;
520 item->li_lv = NULL;
521 num_iovecs += lv->lv_niovecs;
525 * initialise the new context and attach it to the CIL. Then attach
526 * the current context to the CIL committing lsit so it can be found
527 * during log forces to extract the commit lsn of the sequence that
528 * needs to be forced.
530 INIT_LIST_HEAD(&new_ctx->committing);
531 INIT_LIST_HEAD(&new_ctx->busy_extents);
532 new_ctx->sequence = ctx->sequence + 1;
533 new_ctx->cil = cil;
534 cil->xc_ctx = new_ctx;
537 * The switch is now done, so we can drop the context lock and move out
538 * of a shared context. We can't just go straight to the commit record,
539 * though - we need to synchronise with previous and future commits so
540 * that the commit records are correctly ordered in the log to ensure
541 * that we process items during log IO completion in the correct order.
543 * For example, if we get an EFI in one checkpoint and the EFD in the
544 * next (e.g. due to log forces), we do not want the checkpoint with
545 * the EFD to be committed before the checkpoint with the EFI. Hence
546 * we must strictly order the commit records of the checkpoints so
547 * that: a) the checkpoint callbacks are attached to the iclogs in the
548 * correct order; and b) the checkpoints are replayed in correct order
549 * in log recovery.
551 * Hence we need to add this context to the committing context list so
552 * that higher sequences will wait for us to write out a commit record
553 * before they do.
555 * xfs_log_force_lsn requires us to mirror the new sequence into the cil
556 * structure atomically with the addition of this sequence to the
557 * committing list. This also ensures that we can do unlocked checks
558 * against the current sequence in log forces without risking
559 * deferencing a freed context pointer.
561 spin_lock(&cil->xc_push_lock);
562 cil->xc_current_sequence = new_ctx->sequence;
563 spin_unlock(&cil->xc_push_lock);
564 up_write(&cil->xc_ctx_lock);
567 * Build a checkpoint transaction header and write it to the log to
568 * begin the transaction. We need to account for the space used by the
569 * transaction header here as it is not accounted for in xlog_write().
571 * The LSN we need to pass to the log items on transaction commit is
572 * the LSN reported by the first log vector write. If we use the commit
573 * record lsn then we can move the tail beyond the grant write head.
575 tic = ctx->ticket;
576 thdr.th_magic = XFS_TRANS_HEADER_MAGIC;
577 thdr.th_type = XFS_TRANS_CHECKPOINT;
578 thdr.th_tid = tic->t_tid;
579 thdr.th_num_items = num_iovecs;
580 lhdr.i_addr = &thdr;
581 lhdr.i_len = sizeof(xfs_trans_header_t);
582 lhdr.i_type = XLOG_REG_TYPE_TRANSHDR;
583 tic->t_curr_res -= lhdr.i_len + sizeof(xlog_op_header_t);
585 lvhdr.lv_niovecs = 1;
586 lvhdr.lv_iovecp = &lhdr;
587 lvhdr.lv_next = ctx->lv_chain;
589 error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0);
590 if (error)
591 goto out_abort_free_ticket;
594 * now that we've written the checkpoint into the log, strictly
595 * order the commit records so replay will get them in the right order.
597 restart:
598 spin_lock(&cil->xc_push_lock);
599 list_for_each_entry(new_ctx, &cil->xc_committing, committing) {
601 * Avoid getting stuck in this loop because we were woken by the
602 * shutdown, but then went back to sleep once already in the
603 * shutdown state.
605 if (XLOG_FORCED_SHUTDOWN(log)) {
606 spin_unlock(&cil->xc_push_lock);
607 goto out_abort_free_ticket;
611 * Higher sequences will wait for this one so skip them.
612 * Don't wait for our own sequence, either.
614 if (new_ctx->sequence >= ctx->sequence)
615 continue;
616 if (!new_ctx->commit_lsn) {
618 * It is still being pushed! Wait for the push to
619 * complete, then start again from the beginning.
621 xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
622 goto restart;
625 spin_unlock(&cil->xc_push_lock);
627 /* xfs_log_done always frees the ticket on error. */
628 commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, 0);
629 if (commit_lsn == -1)
630 goto out_abort;
632 /* attach all the transactions w/ busy extents to iclog */
633 ctx->log_cb.cb_func = xlog_cil_committed;
634 ctx->log_cb.cb_arg = ctx;
635 error = xfs_log_notify(log->l_mp, commit_iclog, &ctx->log_cb);
636 if (error)
637 goto out_abort;
640 * now the checkpoint commit is complete and we've attached the
641 * callbacks to the iclog we can assign the commit LSN to the context
642 * and wake up anyone who is waiting for the commit to complete.
644 spin_lock(&cil->xc_push_lock);
645 ctx->commit_lsn = commit_lsn;
646 wake_up_all(&cil->xc_commit_wait);
647 spin_unlock(&cil->xc_push_lock);
649 /* release the hounds! */
650 return xfs_log_release_iclog(log->l_mp, commit_iclog);
652 out_skip:
653 up_write(&cil->xc_ctx_lock);
654 xfs_log_ticket_put(new_ctx->ticket);
655 kmem_free(new_ctx);
656 return 0;
658 out_abort_free_ticket:
659 xfs_log_ticket_put(tic);
660 out_abort:
661 xlog_cil_committed(ctx, XFS_LI_ABORTED);
662 return -EIO;
665 static void
666 xlog_cil_push_work(
667 struct work_struct *work)
669 struct xfs_cil *cil = container_of(work, struct xfs_cil,
670 xc_push_work);
671 xlog_cil_push(cil->xc_log);
675 * We need to push CIL every so often so we don't cache more than we can fit in
676 * the log. The limit really is that a checkpoint can't be more than half the
677 * log (the current checkpoint is not allowed to overwrite the previous
678 * checkpoint), but commit latency and memory usage limit this to a smaller
679 * size.
681 static void
682 xlog_cil_push_background(
683 struct xlog *log)
685 struct xfs_cil *cil = log->l_cilp;
688 * The cil won't be empty because we are called while holding the
689 * context lock so whatever we added to the CIL will still be there
691 ASSERT(!list_empty(&cil->xc_cil));
694 * don't do a background push if we haven't used up all the
695 * space available yet.
697 if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
698 return;
700 spin_lock(&cil->xc_push_lock);
701 if (cil->xc_push_seq < cil->xc_current_sequence) {
702 cil->xc_push_seq = cil->xc_current_sequence;
703 queue_work(log->l_mp->m_cil_workqueue, &cil->xc_push_work);
705 spin_unlock(&cil->xc_push_lock);
710 * xlog_cil_push_now() is used to trigger an immediate CIL push to the sequence
711 * number that is passed. When it returns, the work will be queued for
712 * @push_seq, but it won't be completed. The caller is expected to do any
713 * waiting for push_seq to complete if it is required.
715 static void
716 xlog_cil_push_now(
717 struct xlog *log,
718 xfs_lsn_t push_seq)
720 struct xfs_cil *cil = log->l_cilp;
722 if (!cil)
723 return;
725 ASSERT(push_seq && push_seq <= cil->xc_current_sequence);
727 /* start on any pending background push to minimise wait time on it */
728 flush_work(&cil->xc_push_work);
731 * If the CIL is empty or we've already pushed the sequence then
732 * there's no work we need to do.
734 spin_lock(&cil->xc_push_lock);
735 if (list_empty(&cil->xc_cil) || push_seq <= cil->xc_push_seq) {
736 spin_unlock(&cil->xc_push_lock);
737 return;
740 cil->xc_push_seq = push_seq;
741 queue_work(log->l_mp->m_cil_workqueue, &cil->xc_push_work);
742 spin_unlock(&cil->xc_push_lock);
745 bool
746 xlog_cil_empty(
747 struct xlog *log)
749 struct xfs_cil *cil = log->l_cilp;
750 bool empty = false;
752 spin_lock(&cil->xc_push_lock);
753 if (list_empty(&cil->xc_cil))
754 empty = true;
755 spin_unlock(&cil->xc_push_lock);
756 return empty;
760 * Commit a transaction with the given vector to the Committed Item List.
762 * To do this, we need to format the item, pin it in memory if required and
763 * account for the space used by the transaction. Once we have done that we
764 * need to release the unused reservation for the transaction, attach the
765 * transaction to the checkpoint context so we carry the busy extents through
766 * to checkpoint completion, and then unlock all the items in the transaction.
768 * Called with the context lock already held in read mode to lock out
769 * background commit, returns without it held once background commits are
770 * allowed again.
772 void
773 xfs_log_commit_cil(
774 struct xfs_mount *mp,
775 struct xfs_trans *tp,
776 xfs_lsn_t *commit_lsn,
777 int flags)
779 struct xlog *log = mp->m_log;
780 struct xfs_cil *cil = log->l_cilp;
781 int log_flags = 0;
783 if (flags & XFS_TRANS_RELEASE_LOG_RES)
784 log_flags = XFS_LOG_REL_PERM_RESERV;
786 /* lock out background commit */
787 down_read(&cil->xc_ctx_lock);
789 xlog_cil_insert_items(log, tp);
791 /* check we didn't blow the reservation */
792 if (tp->t_ticket->t_curr_res < 0)
793 xlog_print_tic_res(mp, tp->t_ticket);
795 tp->t_commit_lsn = cil->xc_ctx->sequence;
796 if (commit_lsn)
797 *commit_lsn = tp->t_commit_lsn;
799 xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
800 xfs_trans_unreserve_and_mod_sb(tp);
803 * Once all the items of the transaction have been copied to the CIL,
804 * the items can be unlocked and freed.
806 * This needs to be done before we drop the CIL context lock because we
807 * have to update state in the log items and unlock them before they go
808 * to disk. If we don't, then the CIL checkpoint can race with us and
809 * we can run checkpoint completion before we've updated and unlocked
810 * the log items. This affects (at least) processing of stale buffers,
811 * inodes and EFIs.
813 xfs_trans_free_items(tp, tp->t_commit_lsn, 0);
815 xlog_cil_push_background(log);
817 up_read(&cil->xc_ctx_lock);
821 * Conditionally push the CIL based on the sequence passed in.
823 * We only need to push if we haven't already pushed the sequence
824 * number given. Hence the only time we will trigger a push here is
825 * if the push sequence is the same as the current context.
827 * We return the current commit lsn to allow the callers to determine if a
828 * iclog flush is necessary following this call.
830 xfs_lsn_t
831 xlog_cil_force_lsn(
832 struct xlog *log,
833 xfs_lsn_t sequence)
835 struct xfs_cil *cil = log->l_cilp;
836 struct xfs_cil_ctx *ctx;
837 xfs_lsn_t commit_lsn = NULLCOMMITLSN;
839 ASSERT(sequence <= cil->xc_current_sequence);
842 * check to see if we need to force out the current context.
843 * xlog_cil_push() handles racing pushes for the same sequence,
844 * so no need to deal with it here.
846 restart:
847 xlog_cil_push_now(log, sequence);
850 * See if we can find a previous sequence still committing.
851 * We need to wait for all previous sequence commits to complete
852 * before allowing the force of push_seq to go ahead. Hence block
853 * on commits for those as well.
855 spin_lock(&cil->xc_push_lock);
856 list_for_each_entry(ctx, &cil->xc_committing, committing) {
858 * Avoid getting stuck in this loop because we were woken by the
859 * shutdown, but then went back to sleep once already in the
860 * shutdown state.
862 if (XLOG_FORCED_SHUTDOWN(log))
863 goto out_shutdown;
864 if (ctx->sequence > sequence)
865 continue;
866 if (!ctx->commit_lsn) {
868 * It is still being pushed! Wait for the push to
869 * complete, then start again from the beginning.
871 xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
872 goto restart;
874 if (ctx->sequence != sequence)
875 continue;
876 /* found it! */
877 commit_lsn = ctx->commit_lsn;
881 * The call to xlog_cil_push_now() executes the push in the background.
882 * Hence by the time we have got here it our sequence may not have been
883 * pushed yet. This is true if the current sequence still matches the
884 * push sequence after the above wait loop and the CIL still contains
885 * dirty objects. This is guaranteed by the push code first adding the
886 * context to the committing list before emptying the CIL.
888 * Hence if we don't find the context in the committing list and the
889 * current sequence number is unchanged then the CIL contents are
890 * significant. If the CIL is empty, if means there was nothing to push
891 * and that means there is nothing to wait for. If the CIL is not empty,
892 * it means we haven't yet started the push, because if it had started
893 * we would have found the context on the committing list.
895 if (sequence == cil->xc_current_sequence &&
896 !list_empty(&cil->xc_cil)) {
897 spin_unlock(&cil->xc_push_lock);
898 goto restart;
901 spin_unlock(&cil->xc_push_lock);
902 return commit_lsn;
905 * We detected a shutdown in progress. We need to trigger the log force
906 * to pass through it's iclog state machine error handling, even though
907 * we are already in a shutdown state. Hence we can't return
908 * NULLCOMMITLSN here as that has special meaning to log forces (i.e.
909 * LSN is already stable), so we return a zero LSN instead.
911 out_shutdown:
912 spin_unlock(&cil->xc_push_lock);
913 return 0;
917 * Check if the current log item was first committed in this sequence.
918 * We can't rely on just the log item being in the CIL, we have to check
919 * the recorded commit sequence number.
921 * Note: for this to be used in a non-racy manner, it has to be called with
922 * CIL flushing locked out. As a result, it should only be used during the
923 * transaction commit process when deciding what to format into the item.
925 bool
926 xfs_log_item_in_current_chkpt(
927 struct xfs_log_item *lip)
929 struct xfs_cil_ctx *ctx;
931 if (list_empty(&lip->li_cil))
932 return false;
934 ctx = lip->li_mountp->m_log->l_cilp->xc_ctx;
937 * li_seq is written on the first commit of a log item to record the
938 * first checkpoint it is written to. Hence if it is different to the
939 * current sequence, we're in a new checkpoint.
941 if (XFS_LSN_CMP(lip->li_seq, ctx->sequence) != 0)
942 return false;
943 return true;
947 * Perform initial CIL structure initialisation.
950 xlog_cil_init(
951 struct xlog *log)
953 struct xfs_cil *cil;
954 struct xfs_cil_ctx *ctx;
956 cil = kmem_zalloc(sizeof(*cil), KM_SLEEP|KM_MAYFAIL);
957 if (!cil)
958 return -ENOMEM;
960 ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL);
961 if (!ctx) {
962 kmem_free(cil);
963 return -ENOMEM;
966 INIT_WORK(&cil->xc_push_work, xlog_cil_push_work);
967 INIT_LIST_HEAD(&cil->xc_cil);
968 INIT_LIST_HEAD(&cil->xc_committing);
969 spin_lock_init(&cil->xc_cil_lock);
970 spin_lock_init(&cil->xc_push_lock);
971 init_rwsem(&cil->xc_ctx_lock);
972 init_waitqueue_head(&cil->xc_commit_wait);
974 INIT_LIST_HEAD(&ctx->committing);
975 INIT_LIST_HEAD(&ctx->busy_extents);
976 ctx->sequence = 1;
977 ctx->cil = cil;
978 cil->xc_ctx = ctx;
979 cil->xc_current_sequence = ctx->sequence;
981 cil->xc_log = log;
982 log->l_cilp = cil;
983 return 0;
986 void
987 xlog_cil_destroy(
988 struct xlog *log)
990 if (log->l_cilp->xc_ctx) {
991 if (log->l_cilp->xc_ctx->ticket)
992 xfs_log_ticket_put(log->l_cilp->xc_ctx->ticket);
993 kmem_free(log->l_cilp->xc_ctx);
996 ASSERT(list_empty(&log->l_cilp->xc_cil));
997 kmem_free(log->l_cilp);