1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
7 #include <linux/backing-dev.h>
10 #include "xfs_shared.h"
11 #include "xfs_format.h"
12 #include "xfs_log_format.h"
13 #include "xfs_trans_resv.h"
14 #include "xfs_mount.h"
15 #include "xfs_trace.h"
17 #include "xfs_log_recover.h"
18 #include "xfs_log_priv.h"
19 #include "xfs_trans.h"
20 #include "xfs_buf_item.h"
21 #include "xfs_errortag.h"
22 #include "xfs_error.h"
25 struct kmem_cache *xfs_buf_cache;
32 * b_sema (caller holds)
36 * b_sema (caller holds)
45 * xfs_buftarg_drain_rele
47 * b_lock (trylock due to inversion)
51 * b_lock (trylock due to inversion)
54 static int __xfs_buf_submit(struct xfs_buf *bp, bool wait);
60 return __xfs_buf_submit(bp, !(bp->b_flags & XBF_ASYNC));
68 * Return true if the buffer is vmapped.
70 * b_addr is null if the buffer is not mapped, but the code is clever
71 * enough to know it doesn't have to map a single page, so the check has
72 * to be both for b_addr and bp->b_page_count > 1.
74 return bp->b_addr && bp->b_page_count > 1;
81 return (bp->b_page_count * PAGE_SIZE);
85 * Bump the I/O in flight count on the buftarg if we haven't yet done so for
86 * this buffer. The count is incremented once per buffer (per hold cycle)
87 * because the corresponding decrement is deferred to buffer release. Buffers
88 * can undergo I/O multiple times in a hold-release cycle and per buffer I/O
89 * tracking adds unnecessary overhead. This is used for sychronization purposes
90 * with unmount (see xfs_buftarg_drain()), so all we really need is a count of
93 * Buffers that are never released (e.g., superblock, iclog buffers) must set
94 * the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count
95 * never reaches zero and unmount hangs indefinitely.
101 if (bp->b_flags & XBF_NO_IOACCT)
104 ASSERT(bp->b_flags & XBF_ASYNC);
105 spin_lock(&bp->b_lock);
106 if (!(bp->b_state & XFS_BSTATE_IN_FLIGHT)) {
107 bp->b_state |= XFS_BSTATE_IN_FLIGHT;
108 percpu_counter_inc(&bp->b_target->bt_io_count);
110 spin_unlock(&bp->b_lock);
114 * Clear the in-flight state on a buffer about to be released to the LRU or
115 * freed and unaccount from the buftarg.
118 __xfs_buf_ioacct_dec(
121 lockdep_assert_held(&bp->b_lock);
123 if (bp->b_state & XFS_BSTATE_IN_FLIGHT) {
124 bp->b_state &= ~XFS_BSTATE_IN_FLIGHT;
125 percpu_counter_dec(&bp->b_target->bt_io_count);
133 spin_lock(&bp->b_lock);
134 __xfs_buf_ioacct_dec(bp);
135 spin_unlock(&bp->b_lock);
139 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
140 * b_lru_ref count so that the buffer is freed immediately when the buffer
141 * reference count falls to zero. If the buffer is already on the LRU, we need
142 * to remove the reference that LRU holds on the buffer.
144 * This prevents build-up of stale buffers on the LRU.
150 ASSERT(xfs_buf_islocked(bp));
152 bp->b_flags |= XBF_STALE;
155 * Clear the delwri status so that a delwri queue walker will not
156 * flush this buffer to disk now that it is stale. The delwri queue has
157 * a reference to the buffer, so this is safe to do.
159 bp->b_flags &= ~_XBF_DELWRI_Q;
162 * Once the buffer is marked stale and unlocked, a subsequent lookup
163 * could reset b_flags. There is no guarantee that the buffer is
164 * unaccounted (released to LRU) before that occurs. Drop in-flight
165 * status now to preserve accounting consistency.
167 spin_lock(&bp->b_lock);
168 __xfs_buf_ioacct_dec(bp);
170 atomic_set(&bp->b_lru_ref, 0);
171 if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
172 (list_lru_del_obj(&bp->b_target->bt_lru, &bp->b_lru)))
173 atomic_dec(&bp->b_hold);
175 ASSERT(atomic_read(&bp->b_hold) >= 1);
176 spin_unlock(&bp->b_lock);
184 ASSERT(bp->b_maps == NULL);
185 bp->b_map_count = map_count;
187 if (map_count == 1) {
188 bp->b_maps = &bp->__b_map;
192 bp->b_maps = kmem_zalloc(map_count * sizeof(struct xfs_buf_map),
200 * Frees b_pages if it was allocated.
206 if (bp->b_maps != &bp->__b_map) {
207 kmem_free(bp->b_maps);
214 struct xfs_buftarg *target,
215 struct xfs_buf_map *map,
217 xfs_buf_flags_t flags,
218 struct xfs_buf **bpp)
225 bp = kmem_cache_zalloc(xfs_buf_cache, GFP_NOFS | __GFP_NOFAIL);
228 * We don't want certain flags to appear in b_flags unless they are
229 * specifically set by later operations on the buffer.
231 flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
233 atomic_set(&bp->b_hold, 1);
234 atomic_set(&bp->b_lru_ref, 1);
235 init_completion(&bp->b_iowait);
236 INIT_LIST_HEAD(&bp->b_lru);
237 INIT_LIST_HEAD(&bp->b_list);
238 INIT_LIST_HEAD(&bp->b_li_list);
239 sema_init(&bp->b_sema, 0); /* held, no waiters */
240 spin_lock_init(&bp->b_lock);
241 bp->b_target = target;
242 bp->b_mount = target->bt_mount;
246 * Set length and io_length to the same value initially.
247 * I/O routines should use io_length, which will be the same in
248 * most cases but may be reset (e.g. XFS recovery).
250 error = xfs_buf_get_maps(bp, nmaps);
252 kmem_cache_free(xfs_buf_cache, bp);
256 bp->b_rhash_key = map[0].bm_bn;
258 for (i = 0; i < nmaps; i++) {
259 bp->b_maps[i].bm_bn = map[i].bm_bn;
260 bp->b_maps[i].bm_len = map[i].bm_len;
261 bp->b_length += map[i].bm_len;
264 atomic_set(&bp->b_pin_count, 0);
265 init_waitqueue_head(&bp->b_waiters);
267 XFS_STATS_INC(bp->b_mount, xb_create);
268 trace_xfs_buf_init(bp, _RET_IP_);
280 ASSERT(bp->b_flags & _XBF_PAGES);
282 if (xfs_buf_is_vmapped(bp))
283 vm_unmap_ram(bp->b_addr, bp->b_page_count);
285 for (i = 0; i < bp->b_page_count; i++) {
287 __free_page(bp->b_pages[i]);
289 mm_account_reclaimed_pages(bp->b_page_count);
291 if (bp->b_pages != bp->b_page_array)
292 kmem_free(bp->b_pages);
294 bp->b_flags &= ~_XBF_PAGES;
298 xfs_buf_free_callback(
299 struct callback_head *cb)
301 struct xfs_buf *bp = container_of(cb, struct xfs_buf, b_rcu);
303 xfs_buf_free_maps(bp);
304 kmem_cache_free(xfs_buf_cache, bp);
311 trace_xfs_buf_free(bp, _RET_IP_);
313 ASSERT(list_empty(&bp->b_lru));
315 if (bp->b_flags & _XBF_PAGES)
316 xfs_buf_free_pages(bp);
317 else if (bp->b_flags & _XBF_KMEM)
318 kmem_free(bp->b_addr);
320 call_rcu(&bp->b_rcu, xfs_buf_free_callback);
326 xfs_buf_flags_t flags)
328 xfs_km_flags_t kmflag_mask = KM_NOFS;
329 size_t size = BBTOB(bp->b_length);
331 /* Assure zeroed buffer for non-read cases. */
332 if (!(flags & XBF_READ))
333 kmflag_mask |= KM_ZERO;
335 bp->b_addr = kmem_alloc(size, kmflag_mask);
339 if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
340 ((unsigned long)bp->b_addr & PAGE_MASK)) {
341 /* b_addr spans two pages - use alloc_page instead */
342 kmem_free(bp->b_addr);
346 bp->b_offset = offset_in_page(bp->b_addr);
347 bp->b_pages = bp->b_page_array;
348 bp->b_pages[0] = kmem_to_page(bp->b_addr);
349 bp->b_page_count = 1;
350 bp->b_flags |= _XBF_KMEM;
357 xfs_buf_flags_t flags)
359 gfp_t gfp_mask = __GFP_NOWARN;
362 if (flags & XBF_READ_AHEAD)
363 gfp_mask |= __GFP_NORETRY;
365 gfp_mask |= GFP_NOFS;
367 /* Make sure that we have a page list */
368 bp->b_page_count = DIV_ROUND_UP(BBTOB(bp->b_length), PAGE_SIZE);
369 if (bp->b_page_count <= XB_PAGES) {
370 bp->b_pages = bp->b_page_array;
372 bp->b_pages = kzalloc(sizeof(struct page *) * bp->b_page_count,
377 bp->b_flags |= _XBF_PAGES;
379 /* Assure zeroed buffer for non-read cases. */
380 if (!(flags & XBF_READ))
381 gfp_mask |= __GFP_ZERO;
384 * Bulk filling of pages can take multiple calls. Not filling the entire
385 * array is not an allocation failure, so don't back off if we get at
386 * least one extra page.
391 filled = alloc_pages_bulk_array(gfp_mask, bp->b_page_count,
393 if (filled == bp->b_page_count) {
394 XFS_STATS_INC(bp->b_mount, xb_page_found);
401 if (flags & XBF_READ_AHEAD) {
402 xfs_buf_free_pages(bp);
406 XFS_STATS_INC(bp->b_mount, xb_page_retries);
407 memalloc_retry_wait(gfp_mask);
413 * Map buffer into kernel address-space if necessary.
418 xfs_buf_flags_t flags)
420 ASSERT(bp->b_flags & _XBF_PAGES);
421 if (bp->b_page_count == 1) {
422 /* A single page buffer is always mappable */
423 bp->b_addr = page_address(bp->b_pages[0]);
424 } else if (flags & XBF_UNMAPPED) {
431 * vm_map_ram() will allocate auxiliary structures (e.g.
432 * pagetables) with GFP_KERNEL, yet we are likely to be under
433 * GFP_NOFS context here. Hence we need to tell memory reclaim
434 * that we are in such a context via PF_MEMALLOC_NOFS to prevent
435 * memory reclaim re-entering the filesystem here and
436 * potentially deadlocking.
438 nofs_flag = memalloc_nofs_save();
440 bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
445 } while (retried++ <= 1);
446 memalloc_nofs_restore(nofs_flag);
456 * Finding and Reading Buffers
460 struct rhashtable_compare_arg *arg,
463 const struct xfs_buf_map *map = arg->key;
464 const struct xfs_buf *bp = obj;
467 * The key hashing in the lookup path depends on the key being the
468 * first element of the compare_arg, make sure to assert this.
470 BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
472 if (bp->b_rhash_key != map->bm_bn)
475 if (unlikely(bp->b_length != map->bm_len)) {
477 * found a block number match. If the range doesn't
478 * match, the only way this is allowed is if the buffer
479 * in the cache is stale and the transaction that made
480 * it stale has not yet committed. i.e. we are
481 * reallocating a busy extent. Skip this buffer and
482 * continue searching for an exact match.
484 if (!(map->bm_flags & XBM_LIVESCAN))
485 ASSERT(bp->b_flags & XBF_STALE);
491 static const struct rhashtable_params xfs_buf_hash_params = {
492 .min_size = 32, /* empty AGs have minimal footprint */
494 .key_len = sizeof(xfs_daddr_t),
495 .key_offset = offsetof(struct xfs_buf, b_rhash_key),
496 .head_offset = offsetof(struct xfs_buf, b_rhash_head),
497 .automatic_shrinking = true,
498 .obj_cmpfn = _xfs_buf_obj_cmp,
503 struct xfs_perag *pag)
505 spin_lock_init(&pag->pag_buf_lock);
506 return rhashtable_init(&pag->pag_buf_hash, &xfs_buf_hash_params);
510 xfs_buf_hash_destroy(
511 struct xfs_perag *pag)
513 rhashtable_destroy(&pag->pag_buf_hash);
518 struct xfs_buftarg *btp,
519 struct xfs_buf_map *map)
523 /* Check for IOs smaller than the sector size / not sector aligned */
524 ASSERT(!(BBTOB(map->bm_len) < btp->bt_meta_sectorsize));
525 ASSERT(!(BBTOB(map->bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
528 * Corrupted block numbers can get through to here, unfortunately, so we
529 * have to check that the buffer falls within the filesystem bounds.
531 eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
532 if (map->bm_bn < 0 || map->bm_bn >= eofs) {
533 xfs_alert(btp->bt_mount,
534 "%s: daddr 0x%llx out of range, EOFS 0x%llx",
535 __func__, map->bm_bn, eofs);
537 return -EFSCORRUPTED;
545 xfs_buf_flags_t flags)
547 if (flags & XBF_TRYLOCK) {
548 if (!xfs_buf_trylock(bp)) {
549 XFS_STATS_INC(bp->b_mount, xb_busy_locked);
554 XFS_STATS_INC(bp->b_mount, xb_get_locked_waited);
558 * if the buffer is stale, clear all the external state associated with
559 * it. We need to keep flags such as how we allocated the buffer memory
562 if (bp->b_flags & XBF_STALE) {
563 if (flags & XBF_LIVESCAN) {
567 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
568 bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
576 struct xfs_perag *pag,
577 struct xfs_buf_map *map,
578 xfs_buf_flags_t flags,
579 struct xfs_buf **bpp)
585 bp = rhashtable_lookup(&pag->pag_buf_hash, map, xfs_buf_hash_params);
586 if (!bp || !atomic_inc_not_zero(&bp->b_hold)) {
592 error = xfs_buf_find_lock(bp, flags);
598 trace_xfs_buf_find(bp, flags, _RET_IP_);
604 * Insert the new_bp into the hash table. This consumes the perag reference
605 * taken for the lookup regardless of the result of the insert.
609 struct xfs_buftarg *btp,
610 struct xfs_perag *pag,
611 struct xfs_buf_map *cmap,
612 struct xfs_buf_map *map,
614 xfs_buf_flags_t flags,
615 struct xfs_buf **bpp)
617 struct xfs_buf *new_bp;
621 error = _xfs_buf_alloc(btp, map, nmaps, flags, &new_bp);
626 * For buffers that fit entirely within a single page, first attempt to
627 * allocate the memory from the heap to minimise memory usage. If we
628 * can't get heap memory for these small buffers, we fall back to using
629 * the page allocator.
631 if (BBTOB(new_bp->b_length) >= PAGE_SIZE ||
632 xfs_buf_alloc_kmem(new_bp, flags) < 0) {
633 error = xfs_buf_alloc_pages(new_bp, flags);
638 spin_lock(&pag->pag_buf_lock);
639 bp = rhashtable_lookup_get_insert_fast(&pag->pag_buf_hash,
640 &new_bp->b_rhash_head, xfs_buf_hash_params);
643 spin_unlock(&pag->pag_buf_lock);
647 /* found an existing buffer */
648 atomic_inc(&bp->b_hold);
649 spin_unlock(&pag->pag_buf_lock);
650 error = xfs_buf_find_lock(bp, flags);
658 /* The new buffer keeps the perag reference until it is freed. */
660 spin_unlock(&pag->pag_buf_lock);
665 xfs_buf_free(new_bp);
672 * Assembles a buffer covering the specified range. The code is optimised for
673 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
674 * more hits than misses.
678 struct xfs_buftarg *btp,
679 struct xfs_buf_map *map,
681 xfs_buf_flags_t flags,
682 struct xfs_buf **bpp)
684 struct xfs_perag *pag;
685 struct xfs_buf *bp = NULL;
686 struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
690 if (flags & XBF_LIVESCAN)
691 cmap.bm_flags |= XBM_LIVESCAN;
692 for (i = 0; i < nmaps; i++)
693 cmap.bm_len += map[i].bm_len;
695 error = xfs_buf_map_verify(btp, &cmap);
699 pag = xfs_perag_get(btp->bt_mount,
700 xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
702 error = xfs_buf_lookup(pag, &cmap, flags, &bp);
703 if (error && error != -ENOENT)
706 /* cache hits always outnumber misses by at least 10:1 */
708 XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
710 if (flags & XBF_INCORE)
713 /* xfs_buf_find_insert() consumes the perag reference. */
714 error = xfs_buf_find_insert(btp, pag, &cmap, map, nmaps,
719 XFS_STATS_INC(btp->bt_mount, xb_get_locked);
723 /* We do not hold a perag reference anymore. */
725 error = _xfs_buf_map_pages(bp, flags);
726 if (unlikely(error)) {
727 xfs_warn_ratelimited(btp->bt_mount,
728 "%s: failed to map %u pages", __func__,
736 * Clear b_error if this is a lookup from a caller that doesn't expect
737 * valid data to be found in the buffer.
739 if (!(flags & XBF_READ))
740 xfs_buf_ioerror(bp, 0);
742 XFS_STATS_INC(btp->bt_mount, xb_get);
743 trace_xfs_buf_get(bp, flags, _RET_IP_);
755 xfs_buf_flags_t flags)
757 ASSERT(!(flags & XBF_WRITE));
758 ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
760 bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD | XBF_DONE);
761 bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
763 return xfs_buf_submit(bp);
767 * Reverify a buffer found in cache without an attached ->b_ops.
769 * If the caller passed an ops structure and the buffer doesn't have ops
770 * assigned, set the ops and use it to verify the contents. If verification
771 * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
772 * already in XBF_DONE state on entry.
774 * Under normal operations, every in-core buffer is verified on read I/O
775 * completion. There are two scenarios that can lead to in-core buffers without
776 * an assigned ->b_ops. The first is during log recovery of buffers on a V4
777 * filesystem, though these buffers are purged at the end of recovery. The
778 * other is online repair, which intentionally reads with a NULL buffer ops to
779 * run several verifiers across an in-core buffer in order to establish buffer
780 * type. If repair can't establish that, the buffer will be left in memory
781 * with NULL buffer ops.
786 const struct xfs_buf_ops *ops)
788 ASSERT(bp->b_flags & XBF_DONE);
789 ASSERT(bp->b_error == 0);
791 if (!ops || bp->b_ops)
795 bp->b_ops->verify_read(bp);
797 bp->b_flags &= ~XBF_DONE;
803 struct xfs_buftarg *target,
804 struct xfs_buf_map *map,
806 xfs_buf_flags_t flags,
807 struct xfs_buf **bpp,
808 const struct xfs_buf_ops *ops,
817 error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
821 trace_xfs_buf_read(bp, flags, _RET_IP_);
823 if (!(bp->b_flags & XBF_DONE)) {
824 /* Initiate the buffer read and wait. */
825 XFS_STATS_INC(target->bt_mount, xb_get_read);
827 error = _xfs_buf_read(bp, flags);
829 /* Readahead iodone already dropped the buffer, so exit. */
830 if (flags & XBF_ASYNC)
833 /* Buffer already read; all we need to do is check it. */
834 error = xfs_buf_reverify(bp, ops);
836 /* Readahead already finished; drop the buffer and exit. */
837 if (flags & XBF_ASYNC) {
842 /* We do not want read in the flags */
843 bp->b_flags &= ~XBF_READ;
844 ASSERT(bp->b_ops != NULL || ops == NULL);
848 * If we've had a read error, then the contents of the buffer are
849 * invalid and should not be used. To ensure that a followup read tries
850 * to pull the buffer from disk again, we clear the XBF_DONE flag and
851 * mark the buffer stale. This ensures that anyone who has a current
852 * reference to the buffer will interpret it's contents correctly and
853 * future cache lookups will also treat it as an empty, uninitialised
858 * Check against log shutdown for error reporting because
859 * metadata writeback may require a read first and we need to
860 * report errors in metadata writeback until the log is shut
861 * down. High level transaction read functions already check
862 * against mount shutdown, anyway, so we only need to be
863 * concerned about low level IO interactions here.
865 if (!xlog_is_shutdown(target->bt_mount->m_log))
866 xfs_buf_ioerror_alert(bp, fa);
868 bp->b_flags &= ~XBF_DONE;
872 /* bad CRC means corrupted metadata */
873 if (error == -EFSBADCRC)
874 error = -EFSCORRUPTED;
883 * If we are not low on memory then do the readahead in a deadlock
887 xfs_buf_readahead_map(
888 struct xfs_buftarg *target,
889 struct xfs_buf_map *map,
891 const struct xfs_buf_ops *ops)
895 xfs_buf_read_map(target, map, nmaps,
896 XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops,
901 * Read an uncached buffer from disk. Allocates and returns a locked
902 * buffer containing the disk contents or nothing. Uncached buffers always have
903 * a cache index of XFS_BUF_DADDR_NULL so we can easily determine if the buffer
904 * is cached or uncached during fault diagnosis.
907 xfs_buf_read_uncached(
908 struct xfs_buftarg *target,
911 xfs_buf_flags_t flags,
912 struct xfs_buf **bpp,
913 const struct xfs_buf_ops *ops)
920 error = xfs_buf_get_uncached(target, numblks, flags, &bp);
924 /* set up the buffer for a read IO */
925 ASSERT(bp->b_map_count == 1);
926 bp->b_rhash_key = XFS_BUF_DADDR_NULL;
927 bp->b_maps[0].bm_bn = daddr;
928 bp->b_flags |= XBF_READ;
943 xfs_buf_get_uncached(
944 struct xfs_buftarg *target,
946 xfs_buf_flags_t flags,
947 struct xfs_buf **bpp)
951 DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
955 /* flags might contain irrelevant bits, pass only what we care about */
956 error = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT, &bp);
960 error = xfs_buf_alloc_pages(bp, flags);
964 error = _xfs_buf_map_pages(bp, 0);
965 if (unlikely(error)) {
966 xfs_warn(target->bt_mount,
967 "%s: failed to map pages", __func__);
971 trace_xfs_buf_get_uncached(bp, _RET_IP_);
981 * Increment reference count on buffer, to hold the buffer concurrently
982 * with another thread which may release (free) the buffer asynchronously.
983 * Must hold the buffer already to call this function.
989 trace_xfs_buf_hold(bp, _RET_IP_);
990 atomic_inc(&bp->b_hold);
994 * Release a hold on the specified buffer. If the hold count is 1, the buffer is
995 * placed on LRU or freed (depending on b_lru_ref).
1001 struct xfs_perag *pag = bp->b_pag;
1003 bool freebuf = false;
1005 trace_xfs_buf_rele(bp, _RET_IP_);
1008 ASSERT(list_empty(&bp->b_lru));
1009 if (atomic_dec_and_test(&bp->b_hold)) {
1010 xfs_buf_ioacct_dec(bp);
1016 ASSERT(atomic_read(&bp->b_hold) > 0);
1019 * We grab the b_lock here first to serialise racing xfs_buf_rele()
1020 * calls. The pag_buf_lock being taken on the last reference only
1021 * serialises against racing lookups in xfs_buf_find(). IOWs, the second
1022 * to last reference we drop here is not serialised against the last
1023 * reference until we take bp->b_lock. Hence if we don't grab b_lock
1024 * first, the last "release" reference can win the race to the lock and
1025 * free the buffer before the second-to-last reference is processed,
1026 * leading to a use-after-free scenario.
1028 spin_lock(&bp->b_lock);
1029 release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock);
1032 * Drop the in-flight state if the buffer is already on the LRU
1033 * and it holds the only reference. This is racy because we
1034 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
1035 * ensures the decrement occurs only once per-buf.
1037 if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))
1038 __xfs_buf_ioacct_dec(bp);
1042 /* the last reference has been dropped ... */
1043 __xfs_buf_ioacct_dec(bp);
1044 if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
1046 * If the buffer is added to the LRU take a new reference to the
1047 * buffer for the LRU and clear the (now stale) dispose list
1050 if (list_lru_add_obj(&bp->b_target->bt_lru, &bp->b_lru)) {
1051 bp->b_state &= ~XFS_BSTATE_DISPOSE;
1052 atomic_inc(&bp->b_hold);
1054 spin_unlock(&pag->pag_buf_lock);
1057 * most of the time buffers will already be removed from the
1058 * LRU, so optimise that case by checking for the
1059 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1060 * was on was the disposal list
1062 if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
1063 list_lru_del_obj(&bp->b_target->bt_lru, &bp->b_lru);
1065 ASSERT(list_empty(&bp->b_lru));
1068 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1069 rhashtable_remove_fast(&pag->pag_buf_hash, &bp->b_rhash_head,
1070 xfs_buf_hash_params);
1071 spin_unlock(&pag->pag_buf_lock);
1077 spin_unlock(&bp->b_lock);
1085 * Lock a buffer object, if it is not already locked.
1087 * If we come across a stale, pinned, locked buffer, we know that we are
1088 * being asked to lock a buffer that has been reallocated. Because it is
1089 * pinned, we know that the log has not been pushed to disk and hence it
1090 * will still be locked. Rather than continuing to have trylock attempts
1091 * fail until someone else pushes the log, push it ourselves before
1092 * returning. This means that the xfsaild will not get stuck trying
1093 * to push on stale inode buffers.
1101 locked = down_trylock(&bp->b_sema) == 0;
1103 trace_xfs_buf_trylock(bp, _RET_IP_);
1105 trace_xfs_buf_trylock_fail(bp, _RET_IP_);
1110 * Lock a buffer object.
1112 * If we come across a stale, pinned, locked buffer, we know that we
1113 * are being asked to lock a buffer that has been reallocated. Because
1114 * it is pinned, we know that the log has not been pushed to disk and
1115 * hence it will still be locked. Rather than sleeping until someone
1116 * else pushes the log, push it ourselves before trying to get the lock.
1122 trace_xfs_buf_lock(bp, _RET_IP_);
1124 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
1125 xfs_log_force(bp->b_mount, 0);
1128 trace_xfs_buf_lock_done(bp, _RET_IP_);
1135 ASSERT(xfs_buf_islocked(bp));
1138 trace_xfs_buf_unlock(bp, _RET_IP_);
1145 DECLARE_WAITQUEUE (wait, current);
1147 if (atomic_read(&bp->b_pin_count) == 0)
1150 add_wait_queue(&bp->b_waiters, &wait);
1152 set_current_state(TASK_UNINTERRUPTIBLE);
1153 if (atomic_read(&bp->b_pin_count) == 0)
1157 remove_wait_queue(&bp->b_waiters, &wait);
1158 set_current_state(TASK_RUNNING);
1162 xfs_buf_ioerror_alert_ratelimited(
1165 static unsigned long lasttime;
1166 static struct xfs_buftarg *lasttarg;
1168 if (bp->b_target != lasttarg ||
1169 time_after(jiffies, (lasttime + 5*HZ))) {
1171 xfs_buf_ioerror_alert(bp, __this_address);
1173 lasttarg = bp->b_target;
1177 * Account for this latest trip around the retry handler, and decide if
1178 * we've failed enough times to constitute a permanent failure.
1181 xfs_buf_ioerror_permanent(
1183 struct xfs_error_cfg *cfg)
1185 struct xfs_mount *mp = bp->b_mount;
1187 if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
1188 ++bp->b_retries > cfg->max_retries)
1190 if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1191 time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
1194 /* At unmount we may treat errors differently */
1195 if (xfs_is_unmounting(mp) && mp->m_fail_unmount)
1202 * On a sync write or shutdown we just want to stale the buffer and let the
1203 * caller handle the error in bp->b_error appropriately.
1205 * If the write was asynchronous then no one will be looking for the error. If
1206 * this is the first failure of this type, clear the error state and write the
1207 * buffer out again. This means we always retry an async write failure at least
1208 * once, but we also need to set the buffer up to behave correctly now for
1209 * repeated failures.
1211 * If we get repeated async write failures, then we take action according to the
1212 * error configuration we have been set up to use.
1214 * Returns true if this function took care of error handling and the caller must
1215 * not touch the buffer again. Return false if the caller should proceed with
1216 * normal I/O completion handling.
1219 xfs_buf_ioend_handle_error(
1222 struct xfs_mount *mp = bp->b_mount;
1223 struct xfs_error_cfg *cfg;
1226 * If we've already shutdown the journal because of I/O errors, there's
1227 * no point in giving this a retry.
1229 if (xlog_is_shutdown(mp->m_log))
1232 xfs_buf_ioerror_alert_ratelimited(bp);
1235 * We're not going to bother about retrying this during recovery.
1238 if (bp->b_flags & _XBF_LOGRECOVERY) {
1239 xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1244 * Synchronous writes will have callers process the error.
1246 if (!(bp->b_flags & XBF_ASYNC))
1249 trace_xfs_buf_iodone_async(bp, _RET_IP_);
1251 cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
1252 if (bp->b_last_error != bp->b_error ||
1253 !(bp->b_flags & (XBF_STALE | XBF_WRITE_FAIL))) {
1254 bp->b_last_error = bp->b_error;
1255 if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1256 !bp->b_first_retry_time)
1257 bp->b_first_retry_time = jiffies;
1262 * Permanent error - we need to trigger a shutdown if we haven't already
1263 * to indicate that inconsistency will result from this action.
1265 if (xfs_buf_ioerror_permanent(bp, cfg)) {
1266 xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1270 /* Still considered a transient error. Caller will schedule retries. */
1271 if (bp->b_flags & _XBF_INODES)
1272 xfs_buf_inode_io_fail(bp);
1273 else if (bp->b_flags & _XBF_DQUOTS)
1274 xfs_buf_dquot_io_fail(bp);
1276 ASSERT(list_empty(&bp->b_li_list));
1277 xfs_buf_ioerror(bp, 0);
1282 xfs_buf_ioerror(bp, 0);
1283 bp->b_flags |= (XBF_DONE | XBF_WRITE_FAIL);
1288 bp->b_flags |= XBF_DONE;
1289 bp->b_flags &= ~XBF_WRITE;
1290 trace_xfs_buf_error_relse(bp, _RET_IP_);
1298 trace_xfs_buf_iodone(bp, _RET_IP_);
1301 * Pull in IO completion errors now. We are guaranteed to be running
1302 * single threaded, so we don't need the lock to read b_io_error.
1304 if (!bp->b_error && bp->b_io_error)
1305 xfs_buf_ioerror(bp, bp->b_io_error);
1307 if (bp->b_flags & XBF_READ) {
1308 if (!bp->b_error && bp->b_ops)
1309 bp->b_ops->verify_read(bp);
1311 bp->b_flags |= XBF_DONE;
1314 bp->b_flags &= ~XBF_WRITE_FAIL;
1315 bp->b_flags |= XBF_DONE;
1318 if (unlikely(bp->b_error) && xfs_buf_ioend_handle_error(bp))
1321 /* clear the retry state */
1322 bp->b_last_error = 0;
1324 bp->b_first_retry_time = 0;
1327 * Note that for things like remote attribute buffers, there may
1328 * not be a buffer log item here, so processing the buffer log
1329 * item must remain optional.
1332 xfs_buf_item_done(bp);
1334 if (bp->b_flags & _XBF_INODES)
1335 xfs_buf_inode_iodone(bp);
1336 else if (bp->b_flags & _XBF_DQUOTS)
1337 xfs_buf_dquot_iodone(bp);
1341 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD |
1344 if (bp->b_flags & XBF_ASYNC)
1347 complete(&bp->b_iowait);
1352 struct work_struct *work)
1354 struct xfs_buf *bp =
1355 container_of(work, struct xfs_buf, b_ioend_work);
1361 xfs_buf_ioend_async(
1364 INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
1365 queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
1372 xfs_failaddr_t failaddr)
1374 ASSERT(error <= 0 && error >= -1000);
1375 bp->b_error = error;
1376 trace_xfs_buf_ioerror(bp, error, failaddr);
1380 xfs_buf_ioerror_alert(
1382 xfs_failaddr_t func)
1384 xfs_buf_alert_ratelimited(bp, "XFS: metadata IO error",
1385 "metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
1386 func, (uint64_t)xfs_buf_daddr(bp),
1387 bp->b_length, -bp->b_error);
1391 * To simulate an I/O failure, the buffer must be locked and held with at least
1392 * three references. The LRU reference is dropped by the stale call. The buf
1393 * item reference is dropped via ioend processing. The third reference is owned
1394 * by the caller and is dropped on I/O completion if the buffer is XBF_ASYNC.
1400 bp->b_flags &= ~XBF_DONE;
1402 xfs_buf_ioerror(bp, -EIO);
1412 ASSERT(xfs_buf_islocked(bp));
1414 bp->b_flags |= XBF_WRITE;
1415 bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
1418 error = xfs_buf_submit(bp);
1420 xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
1428 struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private;
1430 if (!bio->bi_status &&
1431 (bp->b_flags & XBF_WRITE) && (bp->b_flags & XBF_ASYNC) &&
1432 XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_IOERROR))
1433 bio->bi_status = BLK_STS_IOERR;
1436 * don't overwrite existing errors - otherwise we can lose errors on
1437 * buffers that require multiple bios to complete.
1439 if (bio->bi_status) {
1440 int error = blk_status_to_errno(bio->bi_status);
1442 cmpxchg(&bp->b_io_error, 0, error);
1445 if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1446 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1448 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1449 xfs_buf_ioend_async(bp);
1454 xfs_buf_ioapply_map(
1462 unsigned int total_nr_pages = bp->b_page_count;
1465 sector_t sector = bp->b_maps[map].bm_bn;
1469 /* skip the pages in the buffer before the start offset */
1471 offset = *buf_offset;
1472 while (offset >= PAGE_SIZE) {
1474 offset -= PAGE_SIZE;
1478 * Limit the IO size to the length of the current vector, and update the
1479 * remaining IO count for the next time around.
1481 size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1483 *buf_offset += size;
1486 atomic_inc(&bp->b_io_remaining);
1487 nr_pages = bio_max_segs(total_nr_pages);
1489 bio = bio_alloc(bp->b_target->bt_bdev, nr_pages, op, GFP_NOIO);
1490 bio->bi_iter.bi_sector = sector;
1491 bio->bi_end_io = xfs_buf_bio_end_io;
1492 bio->bi_private = bp;
1494 for (; size && nr_pages; nr_pages--, page_index++) {
1495 int rbytes, nbytes = PAGE_SIZE - offset;
1500 rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
1502 if (rbytes < nbytes)
1506 sector += BTOBB(nbytes);
1511 if (likely(bio->bi_iter.bi_size)) {
1512 if (xfs_buf_is_vmapped(bp)) {
1513 flush_kernel_vmap_range(bp->b_addr,
1514 xfs_buf_vmap_len(bp));
1521 * This is guaranteed not to be the last io reference count
1522 * because the caller (xfs_buf_submit) holds a count itself.
1524 atomic_dec(&bp->b_io_remaining);
1525 xfs_buf_ioerror(bp, -EIO);
1535 struct blk_plug plug;
1542 * Make sure we capture only current IO errors rather than stale errors
1543 * left over from previous use of the buffer (e.g. failed readahead).
1547 if (bp->b_flags & XBF_WRITE) {
1551 * Run the write verifier callback function if it exists. If
1552 * this function fails it will mark the buffer with an error and
1553 * the IO should not be dispatched.
1556 bp->b_ops->verify_write(bp);
1558 xfs_force_shutdown(bp->b_mount,
1559 SHUTDOWN_CORRUPT_INCORE);
1562 } else if (bp->b_rhash_key != XFS_BUF_DADDR_NULL) {
1563 struct xfs_mount *mp = bp->b_mount;
1566 * non-crc filesystems don't attach verifiers during
1567 * log recovery, so don't warn for such filesystems.
1569 if (xfs_has_crc(mp)) {
1571 "%s: no buf ops on daddr 0x%llx len %d",
1572 __func__, xfs_buf_daddr(bp),
1574 xfs_hex_dump(bp->b_addr,
1575 XFS_CORRUPTION_DUMP_LEN);
1581 if (bp->b_flags & XBF_READ_AHEAD)
1585 /* we only use the buffer cache for meta-data */
1589 * Walk all the vectors issuing IO on them. Set up the initial offset
1590 * into the buffer and the desired IO size before we start -
1591 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1594 offset = bp->b_offset;
1595 size = BBTOB(bp->b_length);
1596 blk_start_plug(&plug);
1597 for (i = 0; i < bp->b_map_count; i++) {
1598 xfs_buf_ioapply_map(bp, i, &offset, &size, op);
1602 break; /* all done */
1604 blk_finish_plug(&plug);
1608 * Wait for I/O completion of a sync buffer and return the I/O error code.
1614 ASSERT(!(bp->b_flags & XBF_ASYNC));
1616 trace_xfs_buf_iowait(bp, _RET_IP_);
1617 wait_for_completion(&bp->b_iowait);
1618 trace_xfs_buf_iowait_done(bp, _RET_IP_);
1624 * Buffer I/O submission path, read or write. Asynchronous submission transfers
1625 * the buffer lock ownership and the current reference to the IO. It is not
1626 * safe to reference the buffer after a call to this function unless the caller
1627 * holds an additional reference itself.
1636 trace_xfs_buf_submit(bp, _RET_IP_);
1638 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1641 * On log shutdown we stale and complete the buffer immediately. We can
1642 * be called to read the superblock before the log has been set up, so
1643 * be careful checking the log state.
1645 * Checking the mount shutdown state here can result in the log tail
1646 * moving inappropriately on disk as the log may not yet be shut down.
1647 * i.e. failing this buffer on mount shutdown can remove it from the AIL
1648 * and move the tail of the log forwards without having written this
1649 * buffer to disk. This corrupts the log tail state in memory, and
1650 * because the log may not be shut down yet, it can then be propagated
1651 * to disk before the log is shutdown. Hence we check log shutdown
1652 * state here rather than mount state to avoid corrupting the log tail
1655 if (bp->b_mount->m_log &&
1656 xlog_is_shutdown(bp->b_mount->m_log)) {
1657 xfs_buf_ioend_fail(bp);
1662 * Grab a reference so the buffer does not go away underneath us. For
1663 * async buffers, I/O completion drops the callers reference, which
1664 * could occur before submission returns.
1668 if (bp->b_flags & XBF_WRITE)
1669 xfs_buf_wait_unpin(bp);
1671 /* clear the internal error state to avoid spurious errors */
1675 * Set the count to 1 initially, this will stop an I/O completion
1676 * callout which happens before we have started all the I/O from calling
1677 * xfs_buf_ioend too early.
1679 atomic_set(&bp->b_io_remaining, 1);
1680 if (bp->b_flags & XBF_ASYNC)
1681 xfs_buf_ioacct_inc(bp);
1682 _xfs_buf_ioapply(bp);
1685 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1686 * reference we took above. If we drop it to zero, run completion so
1687 * that we don't return to the caller with completion still pending.
1689 if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1690 if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
1693 xfs_buf_ioend_async(bp);
1697 error = xfs_buf_iowait(bp);
1700 * Release the hold that keeps the buffer referenced for the entire
1701 * I/O. Note that if the buffer is async, it is not safe to reference
1702 * after this release.
1716 return bp->b_addr + offset;
1718 page = bp->b_pages[offset >> PAGE_SHIFT];
1719 return page_address(page) + (offset & (PAGE_SIZE-1));
1730 bend = boff + bsize;
1731 while (boff < bend) {
1733 int page_index, page_offset, csize;
1735 page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1736 page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1737 page = bp->b_pages[page_index];
1738 csize = min_t(size_t, PAGE_SIZE - page_offset,
1739 BBTOB(bp->b_length) - boff);
1741 ASSERT((csize + page_offset) <= PAGE_SIZE);
1743 memset(page_address(page) + page_offset, 0, csize);
1750 * Log a message about and stale a buffer that a caller has decided is corrupt.
1752 * This function should be called for the kinds of metadata corruption that
1753 * cannot be detect from a verifier, such as incorrect inter-block relationship
1754 * data. Do /not/ call this function from a verifier function.
1756 * The buffer must be XBF_DONE prior to the call. Afterwards, the buffer will
1757 * be marked stale, but b_error will not be set. The caller is responsible for
1758 * releasing the buffer or fixing it.
1761 __xfs_buf_mark_corrupt(
1765 ASSERT(bp->b_flags & XBF_DONE);
1767 xfs_buf_corruption_error(bp, fa);
1772 * Handling of buffer targets (buftargs).
1776 * Wait for any bufs with callbacks that have been submitted but have not yet
1777 * returned. These buffers will have an elevated hold count, so wait on those
1778 * while freeing all the buffers only held by the LRU.
1780 static enum lru_status
1781 xfs_buftarg_drain_rele(
1782 struct list_head *item,
1783 struct list_lru_one *lru,
1784 spinlock_t *lru_lock,
1788 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1789 struct list_head *dispose = arg;
1791 if (atomic_read(&bp->b_hold) > 1) {
1792 /* need to wait, so skip it this pass */
1793 trace_xfs_buf_drain_buftarg(bp, _RET_IP_);
1796 if (!spin_trylock(&bp->b_lock))
1800 * clear the LRU reference count so the buffer doesn't get
1801 * ignored in xfs_buf_rele().
1803 atomic_set(&bp->b_lru_ref, 0);
1804 bp->b_state |= XFS_BSTATE_DISPOSE;
1805 list_lru_isolate_move(lru, item, dispose);
1806 spin_unlock(&bp->b_lock);
1811 * Wait for outstanding I/O on the buftarg to complete.
1815 struct xfs_buftarg *btp)
1818 * First wait on the buftarg I/O count for all in-flight buffers to be
1819 * released. This is critical as new buffers do not make the LRU until
1820 * they are released.
1822 * Next, flush the buffer workqueue to ensure all completion processing
1823 * has finished. Just waiting on buffer locks is not sufficient for
1824 * async IO as the reference count held over IO is not released until
1825 * after the buffer lock is dropped. Hence we need to ensure here that
1826 * all reference counts have been dropped before we start walking the
1829 while (percpu_counter_sum(&btp->bt_io_count))
1831 flush_workqueue(btp->bt_mount->m_buf_workqueue);
1836 struct xfs_buftarg *btp)
1840 bool write_fail = false;
1842 xfs_buftarg_wait(btp);
1844 /* loop until there is nothing left on the lru list. */
1845 while (list_lru_count(&btp->bt_lru)) {
1846 list_lru_walk(&btp->bt_lru, xfs_buftarg_drain_rele,
1847 &dispose, LONG_MAX);
1849 while (!list_empty(&dispose)) {
1851 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1852 list_del_init(&bp->b_lru);
1853 if (bp->b_flags & XBF_WRITE_FAIL) {
1855 xfs_buf_alert_ratelimited(bp,
1856 "XFS: Corruption Alert",
1857 "Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
1858 (long long)xfs_buf_daddr(bp));
1867 * If one or more failed buffers were freed, that means dirty metadata
1868 * was thrown away. This should only ever happen after I/O completion
1869 * handling has elevated I/O error(s) to permanent failures and shuts
1873 ASSERT(xlog_is_shutdown(btp->bt_mount->m_log));
1874 xfs_alert(btp->bt_mount,
1875 "Please run xfs_repair to determine the extent of the problem.");
1879 static enum lru_status
1880 xfs_buftarg_isolate(
1881 struct list_head *item,
1882 struct list_lru_one *lru,
1883 spinlock_t *lru_lock,
1886 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1887 struct list_head *dispose = arg;
1890 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1891 * If we fail to get the lock, just skip it.
1893 if (!spin_trylock(&bp->b_lock))
1896 * Decrement the b_lru_ref count unless the value is already
1897 * zero. If the value is already zero, we need to reclaim the
1898 * buffer, otherwise it gets another trip through the LRU.
1900 if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1901 spin_unlock(&bp->b_lock);
1905 bp->b_state |= XFS_BSTATE_DISPOSE;
1906 list_lru_isolate_move(lru, item, dispose);
1907 spin_unlock(&bp->b_lock);
1911 static unsigned long
1912 xfs_buftarg_shrink_scan(
1913 struct shrinker *shrink,
1914 struct shrink_control *sc)
1916 struct xfs_buftarg *btp = shrink->private_data;
1918 unsigned long freed;
1920 freed = list_lru_shrink_walk(&btp->bt_lru, sc,
1921 xfs_buftarg_isolate, &dispose);
1923 while (!list_empty(&dispose)) {
1925 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1926 list_del_init(&bp->b_lru);
1933 static unsigned long
1934 xfs_buftarg_shrink_count(
1935 struct shrinker *shrink,
1936 struct shrink_control *sc)
1938 struct xfs_buftarg *btp = shrink->private_data;
1939 return list_lru_shrink_count(&btp->bt_lru, sc);
1944 struct xfs_buftarg *btp)
1946 shrinker_free(btp->bt_shrinker);
1947 ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
1948 percpu_counter_destroy(&btp->bt_io_count);
1949 list_lru_destroy(&btp->bt_lru);
1951 fs_put_dax(btp->bt_daxdev, btp->bt_mount);
1952 /* the main block device is closed by kill_block_super */
1953 if (btp->bt_bdev != btp->bt_mount->m_super->s_bdev)
1954 bdev_release(btp->bt_bdev_handle);
1960 xfs_setsize_buftarg(
1962 unsigned int sectorsize)
1964 /* Set up metadata sector size info */
1965 btp->bt_meta_sectorsize = sectorsize;
1966 btp->bt_meta_sectormask = sectorsize - 1;
1968 if (set_blocksize(btp->bt_bdev, sectorsize)) {
1969 xfs_warn(btp->bt_mount,
1970 "Cannot set_blocksize to %u on device %pg",
1971 sectorsize, btp->bt_bdev);
1975 /* Set up device logical sector size mask */
1976 btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);
1977 btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;
1983 * When allocating the initial buffer target we have not yet
1984 * read in the superblock, so don't know what sized sectors
1985 * are being used at this early stage. Play safe.
1988 xfs_setsize_buftarg_early(
1991 return xfs_setsize_buftarg(btp, bdev_logical_block_size(btp->bt_bdev));
1994 struct xfs_buftarg *
1996 struct xfs_mount *mp,
1997 struct bdev_handle *bdev_handle)
2000 const struct dax_holder_operations *ops = NULL;
2002 #if defined(CONFIG_FS_DAX) && defined(CONFIG_MEMORY_FAILURE)
2003 ops = &xfs_dax_holder_operations;
2005 btp = kmem_zalloc(sizeof(*btp), KM_NOFS);
2008 btp->bt_bdev_handle = bdev_handle;
2009 btp->bt_dev = bdev_handle->bdev->bd_dev;
2010 btp->bt_bdev = bdev_handle->bdev;
2011 btp->bt_daxdev = fs_dax_get_by_bdev(btp->bt_bdev, &btp->bt_dax_part_off,
2015 * Buffer IO error rate limiting. Limit it to no more than 10 messages
2016 * per 30 seconds so as to not spam logs too much on repeated errors.
2018 ratelimit_state_init(&btp->bt_ioerror_rl, 30 * HZ,
2019 DEFAULT_RATELIMIT_BURST);
2021 if (xfs_setsize_buftarg_early(btp))
2024 if (list_lru_init(&btp->bt_lru))
2027 if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
2030 btp->bt_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE, "xfs-buf:%s",
2032 if (!btp->bt_shrinker)
2035 btp->bt_shrinker->count_objects = xfs_buftarg_shrink_count;
2036 btp->bt_shrinker->scan_objects = xfs_buftarg_shrink_scan;
2037 btp->bt_shrinker->private_data = btp;
2039 shrinker_register(btp->bt_shrinker);
2044 percpu_counter_destroy(&btp->bt_io_count);
2046 list_lru_destroy(&btp->bt_lru);
2056 list_del_init(&bp->b_list);
2057 wake_up_var(&bp->b_list);
2061 * Cancel a delayed write list.
2063 * Remove each buffer from the list, clear the delwri queue flag and drop the
2064 * associated buffer reference.
2067 xfs_buf_delwri_cancel(
2068 struct list_head *list)
2072 while (!list_empty(list)) {
2073 bp = list_first_entry(list, struct xfs_buf, b_list);
2076 bp->b_flags &= ~_XBF_DELWRI_Q;
2077 xfs_buf_list_del(bp);
2083 * Add a buffer to the delayed write list.
2085 * This queues a buffer for writeout if it hasn't already been. Note that
2086 * neither this routine nor the buffer list submission functions perform
2087 * any internal synchronization. It is expected that the lists are thread-local
2090 * Returns true if we queued up the buffer, or false if it already had
2091 * been on the buffer list.
2094 xfs_buf_delwri_queue(
2096 struct list_head *list)
2098 ASSERT(xfs_buf_islocked(bp));
2099 ASSERT(!(bp->b_flags & XBF_READ));
2102 * If the buffer is already marked delwri it already is queued up
2103 * by someone else for imediate writeout. Just ignore it in that
2106 if (bp->b_flags & _XBF_DELWRI_Q) {
2107 trace_xfs_buf_delwri_queued(bp, _RET_IP_);
2111 trace_xfs_buf_delwri_queue(bp, _RET_IP_);
2114 * If a buffer gets written out synchronously or marked stale while it
2115 * is on a delwri list we lazily remove it. To do this, the other party
2116 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
2117 * It remains referenced and on the list. In a rare corner case it
2118 * might get readded to a delwri list after the synchronous writeout, in
2119 * which case we need just need to re-add the flag here.
2121 bp->b_flags |= _XBF_DELWRI_Q;
2122 if (list_empty(&bp->b_list)) {
2123 atomic_inc(&bp->b_hold);
2124 list_add_tail(&bp->b_list, list);
2131 * Queue a buffer to this delwri list as part of a data integrity operation.
2132 * If the buffer is on any other delwri list, we'll wait for that to clear
2133 * so that the caller can submit the buffer for IO and wait for the result.
2134 * Callers must ensure the buffer is not already on the list.
2137 xfs_buf_delwri_queue_here(
2139 struct list_head *buffer_list)
2142 * We need this buffer to end up on the /caller's/ delwri list, not any
2143 * old list. This can happen if the buffer is marked stale (which
2144 * clears DELWRI_Q) after the AIL queues the buffer to its list but
2145 * before the AIL has a chance to submit the list.
2147 while (!list_empty(&bp->b_list)) {
2149 wait_var_event(&bp->b_list, list_empty(&bp->b_list));
2153 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
2155 xfs_buf_delwri_queue(bp, buffer_list);
2159 * Compare function is more complex than it needs to be because
2160 * the return value is only 32 bits and we are doing comparisons
2166 const struct list_head *a,
2167 const struct list_head *b)
2169 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
2170 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
2173 diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
2182 * Submit buffers for write. If wait_list is specified, the buffers are
2183 * submitted using sync I/O and placed on the wait list such that the caller can
2184 * iowait each buffer. Otherwise async I/O is used and the buffers are released
2185 * at I/O completion time. In either case, buffers remain locked until I/O
2186 * completes and the buffer is released from the queue.
2189 xfs_buf_delwri_submit_buffers(
2190 struct list_head *buffer_list,
2191 struct list_head *wait_list)
2193 struct xfs_buf *bp, *n;
2195 struct blk_plug plug;
2197 list_sort(NULL, buffer_list, xfs_buf_cmp);
2199 blk_start_plug(&plug);
2200 list_for_each_entry_safe(bp, n, buffer_list, b_list) {
2202 if (!xfs_buf_trylock(bp))
2204 if (xfs_buf_ispinned(bp)) {
2214 * Someone else might have written the buffer synchronously or
2215 * marked it stale in the meantime. In that case only the
2216 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
2217 * reference and remove it from the list here.
2219 if (!(bp->b_flags & _XBF_DELWRI_Q)) {
2220 xfs_buf_list_del(bp);
2225 trace_xfs_buf_delwri_split(bp, _RET_IP_);
2228 * If we have a wait list, each buffer (and associated delwri
2229 * queue reference) transfers to it and is submitted
2230 * synchronously. Otherwise, drop the buffer from the delwri
2231 * queue and submit async.
2233 bp->b_flags &= ~_XBF_DELWRI_Q;
2234 bp->b_flags |= XBF_WRITE;
2236 bp->b_flags &= ~XBF_ASYNC;
2237 list_move_tail(&bp->b_list, wait_list);
2239 bp->b_flags |= XBF_ASYNC;
2240 xfs_buf_list_del(bp);
2242 __xfs_buf_submit(bp, false);
2244 blk_finish_plug(&plug);
2250 * Write out a buffer list asynchronously.
2252 * This will take the @buffer_list, write all non-locked and non-pinned buffers
2253 * out and not wait for I/O completion on any of the buffers. This interface
2254 * is only safely useable for callers that can track I/O completion by higher
2255 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
2258 * Note: this function will skip buffers it would block on, and in doing so
2259 * leaves them on @buffer_list so they can be retried on a later pass. As such,
2260 * it is up to the caller to ensure that the buffer list is fully submitted or
2261 * cancelled appropriately when they are finished with the list. Failure to
2262 * cancel or resubmit the list until it is empty will result in leaked buffers
2266 xfs_buf_delwri_submit_nowait(
2267 struct list_head *buffer_list)
2269 return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
2273 * Write out a buffer list synchronously.
2275 * This will take the @buffer_list, write all buffers out and wait for I/O
2276 * completion on all of the buffers. @buffer_list is consumed by the function,
2277 * so callers must have some other way of tracking buffers if they require such
2281 xfs_buf_delwri_submit(
2282 struct list_head *buffer_list)
2284 LIST_HEAD (wait_list);
2285 int error = 0, error2;
2288 xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);
2290 /* Wait for IO to complete. */
2291 while (!list_empty(&wait_list)) {
2292 bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
2294 xfs_buf_list_del(bp);
2297 * Wait on the locked buffer, check for errors and unlock and
2298 * release the delwri queue reference.
2300 error2 = xfs_buf_iowait(bp);
2310 * Push a single buffer on a delwri queue.
2312 * The purpose of this function is to submit a single buffer of a delwri queue
2313 * and return with the buffer still on the original queue. The waiting delwri
2314 * buffer submission infrastructure guarantees transfer of the delwri queue
2315 * buffer reference to a temporary wait list. We reuse this infrastructure to
2316 * transfer the buffer back to the original queue.
2318 * Note the buffer transitions from the queued state, to the submitted and wait
2319 * listed state and back to the queued state during this call. The buffer
2320 * locking and queue management logic between _delwri_pushbuf() and
2321 * _delwri_queue() guarantee that the buffer cannot be queued to another list
2325 xfs_buf_delwri_pushbuf(
2327 struct list_head *buffer_list)
2329 LIST_HEAD (submit_list);
2332 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
2334 trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);
2337 * Isolate the buffer to a new local list so we can submit it for I/O
2338 * independently from the rest of the original list.
2341 list_move(&bp->b_list, &submit_list);
2345 * Delwri submission clears the DELWRI_Q buffer flag and returns with
2346 * the buffer on the wait list with the original reference. Rather than
2347 * bounce the buffer from a local wait list back to the original list
2348 * after I/O completion, reuse the original list as the wait list.
2350 xfs_buf_delwri_submit_buffers(&submit_list, buffer_list);
2353 * The buffer is now locked, under I/O and wait listed on the original
2354 * delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
2355 * return with the buffer unlocked and on the original queue.
2357 error = xfs_buf_iowait(bp);
2358 bp->b_flags |= _XBF_DELWRI_Q;
2364 void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
2367 * Set the lru reference count to 0 based on the error injection tag.
2368 * This allows userspace to disrupt buffer caching for debug/testing
2371 if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
2374 atomic_set(&bp->b_lru_ref, lru_ref);
2378 * Verify an on-disk magic value against the magic value specified in the
2379 * verifier structure. The verifier magic is in disk byte order so the caller is
2380 * expected to pass the value directly from disk.
2387 struct xfs_mount *mp = bp->b_mount;
2390 idx = xfs_has_crc(mp);
2391 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))
2393 return dmagic == bp->b_ops->magic[idx];
2396 * Verify an on-disk magic value against the magic value specified in the
2397 * verifier structure. The verifier magic is in disk byte order so the caller is
2398 * expected to pass the value directly from disk.
2405 struct xfs_mount *mp = bp->b_mount;
2408 idx = xfs_has_crc(mp);
2409 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))
2411 return dmagic == bp->b_ops->magic16[idx];