1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
7 #include <linux/backing-dev.h>
9 #include "xfs_shared.h"
10 #include "xfs_format.h"
11 #include "xfs_log_format.h"
12 #include "xfs_trans_resv.h"
14 #include "xfs_mount.h"
15 #include "xfs_trace.h"
17 #include "xfs_errortag.h"
18 #include "xfs_error.h"
20 static kmem_zone_t *xfs_buf_zone;
22 #define xb_to_gfp(flags) \
23 ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : GFP_NOFS) | __GFP_NOWARN)
30 * b_sema (caller holds)
34 * b_sema (caller holds)
43 * xfs_buftarg_wait_rele
45 * b_lock (trylock due to inversion)
49 * b_lock (trylock due to inversion)
57 * Return true if the buffer is vmapped.
59 * b_addr is null if the buffer is not mapped, but the code is clever
60 * enough to know it doesn't have to map a single page, so the check has
61 * to be both for b_addr and bp->b_page_count > 1.
63 return bp->b_addr && bp->b_page_count > 1;
70 return (bp->b_page_count * PAGE_SIZE) - bp->b_offset;
74 * Bump the I/O in flight count on the buftarg if we haven't yet done so for
75 * this buffer. The count is incremented once per buffer (per hold cycle)
76 * because the corresponding decrement is deferred to buffer release. Buffers
77 * can undergo I/O multiple times in a hold-release cycle and per buffer I/O
78 * tracking adds unnecessary overhead. This is used for sychronization purposes
79 * with unmount (see xfs_wait_buftarg()), so all we really need is a count of
82 * Buffers that are never released (e.g., superblock, iclog buffers) must set
83 * the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count
84 * never reaches zero and unmount hangs indefinitely.
90 if (bp->b_flags & XBF_NO_IOACCT)
93 ASSERT(bp->b_flags & XBF_ASYNC);
94 spin_lock(&bp->b_lock);
95 if (!(bp->b_state & XFS_BSTATE_IN_FLIGHT)) {
96 bp->b_state |= XFS_BSTATE_IN_FLIGHT;
97 percpu_counter_inc(&bp->b_target->bt_io_count);
99 spin_unlock(&bp->b_lock);
103 * Clear the in-flight state on a buffer about to be released to the LRU or
104 * freed and unaccount from the buftarg.
107 __xfs_buf_ioacct_dec(
110 lockdep_assert_held(&bp->b_lock);
112 if (bp->b_state & XFS_BSTATE_IN_FLIGHT) {
113 bp->b_state &= ~XFS_BSTATE_IN_FLIGHT;
114 percpu_counter_dec(&bp->b_target->bt_io_count);
122 spin_lock(&bp->b_lock);
123 __xfs_buf_ioacct_dec(bp);
124 spin_unlock(&bp->b_lock);
128 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
129 * b_lru_ref count so that the buffer is freed immediately when the buffer
130 * reference count falls to zero. If the buffer is already on the LRU, we need
131 * to remove the reference that LRU holds on the buffer.
133 * This prevents build-up of stale buffers on the LRU.
139 ASSERT(xfs_buf_islocked(bp));
141 bp->b_flags |= XBF_STALE;
144 * Clear the delwri status so that a delwri queue walker will not
145 * flush this buffer to disk now that it is stale. The delwri queue has
146 * a reference to the buffer, so this is safe to do.
148 bp->b_flags &= ~_XBF_DELWRI_Q;
151 * Once the buffer is marked stale and unlocked, a subsequent lookup
152 * could reset b_flags. There is no guarantee that the buffer is
153 * unaccounted (released to LRU) before that occurs. Drop in-flight
154 * status now to preserve accounting consistency.
156 spin_lock(&bp->b_lock);
157 __xfs_buf_ioacct_dec(bp);
159 atomic_set(&bp->b_lru_ref, 0);
160 if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
161 (list_lru_del(&bp->b_target->bt_lru, &bp->b_lru)))
162 atomic_dec(&bp->b_hold);
164 ASSERT(atomic_read(&bp->b_hold) >= 1);
165 spin_unlock(&bp->b_lock);
173 ASSERT(bp->b_maps == NULL);
174 bp->b_map_count = map_count;
176 if (map_count == 1) {
177 bp->b_maps = &bp->__b_map;
181 bp->b_maps = kmem_zalloc(map_count * sizeof(struct xfs_buf_map),
189 * Frees b_pages if it was allocated.
195 if (bp->b_maps != &bp->__b_map) {
196 kmem_free(bp->b_maps);
203 struct xfs_buftarg *target,
204 struct xfs_buf_map *map,
206 xfs_buf_flags_t flags,
207 struct xfs_buf **bpp)
214 bp = kmem_zone_zalloc(xfs_buf_zone, KM_NOFS);
219 * We don't want certain flags to appear in b_flags unless they are
220 * specifically set by later operations on the buffer.
222 flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
224 atomic_set(&bp->b_hold, 1);
225 atomic_set(&bp->b_lru_ref, 1);
226 init_completion(&bp->b_iowait);
227 INIT_LIST_HEAD(&bp->b_lru);
228 INIT_LIST_HEAD(&bp->b_list);
229 INIT_LIST_HEAD(&bp->b_li_list);
230 sema_init(&bp->b_sema, 0); /* held, no waiters */
231 spin_lock_init(&bp->b_lock);
232 bp->b_target = target;
233 bp->b_mount = target->bt_mount;
237 * Set length and io_length to the same value initially.
238 * I/O routines should use io_length, which will be the same in
239 * most cases but may be reset (e.g. XFS recovery).
241 error = xfs_buf_get_maps(bp, nmaps);
243 kmem_cache_free(xfs_buf_zone, bp);
247 bp->b_bn = map[0].bm_bn;
249 for (i = 0; i < nmaps; i++) {
250 bp->b_maps[i].bm_bn = map[i].bm_bn;
251 bp->b_maps[i].bm_len = map[i].bm_len;
252 bp->b_length += map[i].bm_len;
255 atomic_set(&bp->b_pin_count, 0);
256 init_waitqueue_head(&bp->b_waiters);
258 XFS_STATS_INC(bp->b_mount, xb_create);
259 trace_xfs_buf_init(bp, _RET_IP_);
266 * Allocate a page array capable of holding a specified number
267 * of pages, and point the page buf at it.
274 /* Make sure that we have a page list */
275 if (bp->b_pages == NULL) {
276 bp->b_page_count = page_count;
277 if (page_count <= XB_PAGES) {
278 bp->b_pages = bp->b_page_array;
280 bp->b_pages = kmem_alloc(sizeof(struct page *) *
281 page_count, KM_NOFS);
282 if (bp->b_pages == NULL)
285 memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
291 * Frees b_pages if it was allocated.
297 if (bp->b_pages != bp->b_page_array) {
298 kmem_free(bp->b_pages);
304 * Releases the specified buffer.
306 * The modification state of any associated pages is left unchanged.
307 * The buffer must not be on any hash - use xfs_buf_rele instead for
308 * hashed and refcounted buffers
314 trace_xfs_buf_free(bp, _RET_IP_);
316 ASSERT(list_empty(&bp->b_lru));
318 if (bp->b_flags & _XBF_PAGES) {
321 if (xfs_buf_is_vmapped(bp))
322 vm_unmap_ram(bp->b_addr - bp->b_offset,
325 for (i = 0; i < bp->b_page_count; i++) {
326 struct page *page = bp->b_pages[i];
330 } else if (bp->b_flags & _XBF_KMEM)
331 kmem_free(bp->b_addr);
332 _xfs_buf_free_pages(bp);
333 xfs_buf_free_maps(bp);
334 kmem_cache_free(xfs_buf_zone, bp);
338 * Allocates all the pages for buffer in question and builds it's page list.
341 xfs_buf_allocate_memory(
346 size_t nbytes, offset;
347 gfp_t gfp_mask = xb_to_gfp(flags);
348 unsigned short page_count, i;
349 xfs_off_t start, end;
351 xfs_km_flags_t kmflag_mask = 0;
354 * assure zeroed buffer for non-read cases.
356 if (!(flags & XBF_READ)) {
357 kmflag_mask |= KM_ZERO;
358 gfp_mask |= __GFP_ZERO;
362 * for buffers that are contained within a single page, just allocate
363 * the memory from the heap - there's no need for the complexity of
364 * page arrays to keep allocation down to order 0.
366 size = BBTOB(bp->b_length);
367 if (size < PAGE_SIZE) {
368 int align_mask = xfs_buftarg_dma_alignment(bp->b_target);
369 bp->b_addr = kmem_alloc_io(size, align_mask,
370 KM_NOFS | kmflag_mask);
372 /* low memory - use alloc_page loop instead */
376 if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
377 ((unsigned long)bp->b_addr & PAGE_MASK)) {
378 /* b_addr spans two pages - use alloc_page instead */
379 kmem_free(bp->b_addr);
383 bp->b_offset = offset_in_page(bp->b_addr);
384 bp->b_pages = bp->b_page_array;
385 bp->b_pages[0] = kmem_to_page(bp->b_addr);
386 bp->b_page_count = 1;
387 bp->b_flags |= _XBF_KMEM;
392 start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT;
393 end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1)
395 page_count = end - start;
396 error = _xfs_buf_get_pages(bp, page_count);
400 offset = bp->b_offset;
401 bp->b_flags |= _XBF_PAGES;
403 for (i = 0; i < bp->b_page_count; i++) {
407 page = alloc_page(gfp_mask);
408 if (unlikely(page == NULL)) {
409 if (flags & XBF_READ_AHEAD) {
410 bp->b_page_count = i;
416 * This could deadlock.
418 * But until all the XFS lowlevel code is revamped to
419 * handle buffer allocation failures we can't do much.
421 if (!(++retries % 100))
423 "%s(%u) possible memory allocation deadlock in %s (mode:0x%x)",
424 current->comm, current->pid,
427 XFS_STATS_INC(bp->b_mount, xb_page_retries);
428 congestion_wait(BLK_RW_ASYNC, HZ/50);
432 XFS_STATS_INC(bp->b_mount, xb_page_found);
434 nbytes = min_t(size_t, size, PAGE_SIZE - offset);
436 bp->b_pages[i] = page;
442 for (i = 0; i < bp->b_page_count; i++)
443 __free_page(bp->b_pages[i]);
444 bp->b_flags &= ~_XBF_PAGES;
449 * Map buffer into kernel address-space if necessary.
456 ASSERT(bp->b_flags & _XBF_PAGES);
457 if (bp->b_page_count == 1) {
458 /* A single page buffer is always mappable */
459 bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
460 } else if (flags & XBF_UNMAPPED) {
467 * vm_map_ram() will allocate auxiliary structures (e.g.
468 * pagetables) with GFP_KERNEL, yet we are likely to be under
469 * GFP_NOFS context here. Hence we need to tell memory reclaim
470 * that we are in such a context via PF_MEMALLOC_NOFS to prevent
471 * memory reclaim re-entering the filesystem here and
472 * potentially deadlocking.
474 nofs_flag = memalloc_nofs_save();
476 bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
481 } while (retried++ <= 1);
482 memalloc_nofs_restore(nofs_flag);
486 bp->b_addr += bp->b_offset;
493 * Finding and Reading Buffers
497 struct rhashtable_compare_arg *arg,
500 const struct xfs_buf_map *map = arg->key;
501 const struct xfs_buf *bp = obj;
504 * The key hashing in the lookup path depends on the key being the
505 * first element of the compare_arg, make sure to assert this.
507 BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
509 if (bp->b_bn != map->bm_bn)
512 if (unlikely(bp->b_length != map->bm_len)) {
514 * found a block number match. If the range doesn't
515 * match, the only way this is allowed is if the buffer
516 * in the cache is stale and the transaction that made
517 * it stale has not yet committed. i.e. we are
518 * reallocating a busy extent. Skip this buffer and
519 * continue searching for an exact match.
521 ASSERT(bp->b_flags & XBF_STALE);
527 static const struct rhashtable_params xfs_buf_hash_params = {
528 .min_size = 32, /* empty AGs have minimal footprint */
530 .key_len = sizeof(xfs_daddr_t),
531 .key_offset = offsetof(struct xfs_buf, b_bn),
532 .head_offset = offsetof(struct xfs_buf, b_rhash_head),
533 .automatic_shrinking = true,
534 .obj_cmpfn = _xfs_buf_obj_cmp,
539 struct xfs_perag *pag)
541 spin_lock_init(&pag->pag_buf_lock);
542 return rhashtable_init(&pag->pag_buf_hash, &xfs_buf_hash_params);
546 xfs_buf_hash_destroy(
547 struct xfs_perag *pag)
549 rhashtable_destroy(&pag->pag_buf_hash);
553 * Look up a buffer in the buffer cache and return it referenced and locked
556 * If @new_bp is supplied and we have a lookup miss, insert @new_bp into the
559 * If XBF_TRYLOCK is set in @flags, only try to lock the buffer and return
560 * -EAGAIN if we fail to lock it.
563 * -EFSCORRUPTED if have been supplied with an invalid address
564 * -EAGAIN on trylock failure
565 * -ENOENT if we fail to find a match and @new_bp was NULL
567 * - @new_bp if we inserted it into the cache
568 * - the buffer we found and locked.
572 struct xfs_buftarg *btp,
573 struct xfs_buf_map *map,
575 xfs_buf_flags_t flags,
576 struct xfs_buf *new_bp,
577 struct xfs_buf **found_bp)
579 struct xfs_perag *pag;
581 struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
587 for (i = 0; i < nmaps; i++)
588 cmap.bm_len += map[i].bm_len;
590 /* Check for IOs smaller than the sector size / not sector aligned */
591 ASSERT(!(BBTOB(cmap.bm_len) < btp->bt_meta_sectorsize));
592 ASSERT(!(BBTOB(cmap.bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
595 * Corrupted block numbers can get through to here, unfortunately, so we
596 * have to check that the buffer falls within the filesystem bounds.
598 eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
599 if (cmap.bm_bn < 0 || cmap.bm_bn >= eofs) {
600 xfs_alert(btp->bt_mount,
601 "%s: daddr 0x%llx out of range, EOFS 0x%llx",
602 __func__, cmap.bm_bn, eofs);
604 return -EFSCORRUPTED;
607 pag = xfs_perag_get(btp->bt_mount,
608 xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
610 spin_lock(&pag->pag_buf_lock);
611 bp = rhashtable_lookup_fast(&pag->pag_buf_hash, &cmap,
612 xfs_buf_hash_params);
614 atomic_inc(&bp->b_hold);
620 XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
621 spin_unlock(&pag->pag_buf_lock);
626 /* the buffer keeps the perag reference until it is freed */
628 rhashtable_insert_fast(&pag->pag_buf_hash, &new_bp->b_rhash_head,
629 xfs_buf_hash_params);
630 spin_unlock(&pag->pag_buf_lock);
635 spin_unlock(&pag->pag_buf_lock);
638 if (!xfs_buf_trylock(bp)) {
639 if (flags & XBF_TRYLOCK) {
641 XFS_STATS_INC(btp->bt_mount, xb_busy_locked);
645 XFS_STATS_INC(btp->bt_mount, xb_get_locked_waited);
649 * if the buffer is stale, clear all the external state associated with
650 * it. We need to keep flags such as how we allocated the buffer memory
653 if (bp->b_flags & XBF_STALE) {
654 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
655 ASSERT(bp->b_iodone == NULL);
656 bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
660 trace_xfs_buf_find(bp, flags, _RET_IP_);
661 XFS_STATS_INC(btp->bt_mount, xb_get_locked);
668 struct xfs_buftarg *target,
671 xfs_buf_flags_t flags)
675 DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
677 error = xfs_buf_find(target, &map, 1, flags, NULL, &bp);
684 * Assembles a buffer covering the specified range. The code is optimised for
685 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
686 * more hits than misses.
690 struct xfs_buftarg *target,
691 struct xfs_buf_map *map,
693 xfs_buf_flags_t flags)
696 struct xfs_buf *new_bp;
699 error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
706 /* cache hit, trylock failure, caller handles failure */
707 ASSERT(flags & XBF_TRYLOCK);
710 /* cache miss, go for insert */
715 * None of the higher layers understand failure types
716 * yet, so return NULL to signal a fatal lookup error.
721 error = _xfs_buf_alloc(target, map, nmaps, flags, &new_bp);
725 error = xfs_buf_allocate_memory(new_bp, flags);
727 xfs_buf_free(new_bp);
731 error = xfs_buf_find(target, map, nmaps, flags, new_bp, &bp);
733 xfs_buf_free(new_bp);
738 xfs_buf_free(new_bp);
742 error = _xfs_buf_map_pages(bp, flags);
743 if (unlikely(error)) {
744 xfs_warn(target->bt_mount,
745 "%s: failed to map pagesn", __func__);
752 * Clear b_error if this is a lookup from a caller that doesn't expect
753 * valid data to be found in the buffer.
755 if (!(flags & XBF_READ))
756 xfs_buf_ioerror(bp, 0);
758 XFS_STATS_INC(target->bt_mount, xb_get);
759 trace_xfs_buf_get(bp, flags, _RET_IP_);
766 xfs_buf_flags_t flags)
768 ASSERT(!(flags & XBF_WRITE));
769 ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
771 bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD);
772 bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
774 return xfs_buf_submit(bp);
778 * Reverify a buffer found in cache without an attached ->b_ops.
780 * If the caller passed an ops structure and the buffer doesn't have ops
781 * assigned, set the ops and use it to verify the contents. If verification
782 * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
783 * already in XBF_DONE state on entry.
785 * Under normal operations, every in-core buffer is verified on read I/O
786 * completion. There are two scenarios that can lead to in-core buffers without
787 * an assigned ->b_ops. The first is during log recovery of buffers on a V4
788 * filesystem, though these buffers are purged at the end of recovery. The
789 * other is online repair, which intentionally reads with a NULL buffer ops to
790 * run several verifiers across an in-core buffer in order to establish buffer
791 * type. If repair can't establish that, the buffer will be left in memory
792 * with NULL buffer ops.
797 const struct xfs_buf_ops *ops)
799 ASSERT(bp->b_flags & XBF_DONE);
800 ASSERT(bp->b_error == 0);
802 if (!ops || bp->b_ops)
806 bp->b_ops->verify_read(bp);
808 bp->b_flags &= ~XBF_DONE;
814 struct xfs_buftarg *target,
815 struct xfs_buf_map *map,
817 xfs_buf_flags_t flags,
818 const struct xfs_buf_ops *ops)
824 bp = xfs_buf_get_map(target, map, nmaps, flags);
828 trace_xfs_buf_read(bp, flags, _RET_IP_);
830 if (!(bp->b_flags & XBF_DONE)) {
831 XFS_STATS_INC(target->bt_mount, xb_get_read);
833 _xfs_buf_read(bp, flags);
837 xfs_buf_reverify(bp, ops);
839 if (flags & XBF_ASYNC) {
841 * Read ahead call which is already satisfied,
848 /* We do not want read in the flags */
849 bp->b_flags &= ~XBF_READ;
850 ASSERT(bp->b_ops != NULL || ops == NULL);
855 * If we are not low on memory then do the readahead in a deadlock
859 xfs_buf_readahead_map(
860 struct xfs_buftarg *target,
861 struct xfs_buf_map *map,
863 const struct xfs_buf_ops *ops)
865 if (bdi_read_congested(target->bt_bdev->bd_bdi))
868 xfs_buf_read_map(target, map, nmaps,
869 XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, ops);
873 * Read an uncached buffer from disk. Allocates and returns a locked
874 * buffer containing the disk contents or nothing.
877 xfs_buf_read_uncached(
878 struct xfs_buftarg *target,
882 struct xfs_buf **bpp,
883 const struct xfs_buf_ops *ops)
889 bp = xfs_buf_get_uncached(target, numblks, flags);
893 /* set up the buffer for a read IO */
894 ASSERT(bp->b_map_count == 1);
895 bp->b_bn = XFS_BUF_DADDR_NULL; /* always null for uncached buffers */
896 bp->b_maps[0].bm_bn = daddr;
897 bp->b_flags |= XBF_READ;
902 int error = bp->b_error;
912 xfs_buf_get_uncached(
913 struct xfs_buftarg *target,
917 unsigned long page_count;
920 DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
922 /* flags might contain irrelevant bits, pass only what we care about */
923 error = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT, &bp);
927 page_count = PAGE_ALIGN(numblks << BBSHIFT) >> PAGE_SHIFT;
928 error = _xfs_buf_get_pages(bp, page_count);
932 for (i = 0; i < page_count; i++) {
933 bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
937 bp->b_flags |= _XBF_PAGES;
939 error = _xfs_buf_map_pages(bp, 0);
940 if (unlikely(error)) {
941 xfs_warn(target->bt_mount,
942 "%s: failed to map pages", __func__);
946 trace_xfs_buf_get_uncached(bp, _RET_IP_);
951 __free_page(bp->b_pages[i]);
952 _xfs_buf_free_pages(bp);
954 xfs_buf_free_maps(bp);
955 kmem_cache_free(xfs_buf_zone, bp);
961 * Increment reference count on buffer, to hold the buffer concurrently
962 * with another thread which may release (free) the buffer asynchronously.
963 * Must hold the buffer already to call this function.
969 trace_xfs_buf_hold(bp, _RET_IP_);
970 atomic_inc(&bp->b_hold);
974 * Release a hold on the specified buffer. If the hold count is 1, the buffer is
975 * placed on LRU or freed (depending on b_lru_ref).
981 struct xfs_perag *pag = bp->b_pag;
983 bool freebuf = false;
985 trace_xfs_buf_rele(bp, _RET_IP_);
988 ASSERT(list_empty(&bp->b_lru));
989 if (atomic_dec_and_test(&bp->b_hold)) {
990 xfs_buf_ioacct_dec(bp);
996 ASSERT(atomic_read(&bp->b_hold) > 0);
999 * We grab the b_lock here first to serialise racing xfs_buf_rele()
1000 * calls. The pag_buf_lock being taken on the last reference only
1001 * serialises against racing lookups in xfs_buf_find(). IOWs, the second
1002 * to last reference we drop here is not serialised against the last
1003 * reference until we take bp->b_lock. Hence if we don't grab b_lock
1004 * first, the last "release" reference can win the race to the lock and
1005 * free the buffer before the second-to-last reference is processed,
1006 * leading to a use-after-free scenario.
1008 spin_lock(&bp->b_lock);
1009 release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock);
1012 * Drop the in-flight state if the buffer is already on the LRU
1013 * and it holds the only reference. This is racy because we
1014 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
1015 * ensures the decrement occurs only once per-buf.
1017 if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))
1018 __xfs_buf_ioacct_dec(bp);
1022 /* the last reference has been dropped ... */
1023 __xfs_buf_ioacct_dec(bp);
1024 if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
1026 * If the buffer is added to the LRU take a new reference to the
1027 * buffer for the LRU and clear the (now stale) dispose list
1030 if (list_lru_add(&bp->b_target->bt_lru, &bp->b_lru)) {
1031 bp->b_state &= ~XFS_BSTATE_DISPOSE;
1032 atomic_inc(&bp->b_hold);
1034 spin_unlock(&pag->pag_buf_lock);
1037 * most of the time buffers will already be removed from the
1038 * LRU, so optimise that case by checking for the
1039 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1040 * was on was the disposal list
1042 if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
1043 list_lru_del(&bp->b_target->bt_lru, &bp->b_lru);
1045 ASSERT(list_empty(&bp->b_lru));
1048 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1049 rhashtable_remove_fast(&pag->pag_buf_hash, &bp->b_rhash_head,
1050 xfs_buf_hash_params);
1051 spin_unlock(&pag->pag_buf_lock);
1057 spin_unlock(&bp->b_lock);
1065 * Lock a buffer object, if it is not already locked.
1067 * If we come across a stale, pinned, locked buffer, we know that we are
1068 * being asked to lock a buffer that has been reallocated. Because it is
1069 * pinned, we know that the log has not been pushed to disk and hence it
1070 * will still be locked. Rather than continuing to have trylock attempts
1071 * fail until someone else pushes the log, push it ourselves before
1072 * returning. This means that the xfsaild will not get stuck trying
1073 * to push on stale inode buffers.
1081 locked = down_trylock(&bp->b_sema) == 0;
1083 trace_xfs_buf_trylock(bp, _RET_IP_);
1085 trace_xfs_buf_trylock_fail(bp, _RET_IP_);
1090 * Lock a buffer object.
1092 * If we come across a stale, pinned, locked buffer, we know that we
1093 * are being asked to lock a buffer that has been reallocated. Because
1094 * it is pinned, we know that the log has not been pushed to disk and
1095 * hence it will still be locked. Rather than sleeping until someone
1096 * else pushes the log, push it ourselves before trying to get the lock.
1102 trace_xfs_buf_lock(bp, _RET_IP_);
1104 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
1105 xfs_log_force(bp->b_mount, 0);
1108 trace_xfs_buf_lock_done(bp, _RET_IP_);
1115 ASSERT(xfs_buf_islocked(bp));
1118 trace_xfs_buf_unlock(bp, _RET_IP_);
1125 DECLARE_WAITQUEUE (wait, current);
1127 if (atomic_read(&bp->b_pin_count) == 0)
1130 add_wait_queue(&bp->b_waiters, &wait);
1132 set_current_state(TASK_UNINTERRUPTIBLE);
1133 if (atomic_read(&bp->b_pin_count) == 0)
1137 remove_wait_queue(&bp->b_waiters, &wait);
1138 set_current_state(TASK_RUNNING);
1142 * Buffer Utility Routines
1149 bool read = bp->b_flags & XBF_READ;
1151 trace_xfs_buf_iodone(bp, _RET_IP_);
1153 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
1156 * Pull in IO completion errors now. We are guaranteed to be running
1157 * single threaded, so we don't need the lock to read b_io_error.
1159 if (!bp->b_error && bp->b_io_error)
1160 xfs_buf_ioerror(bp, bp->b_io_error);
1162 /* Only validate buffers that were read without errors */
1163 if (read && !bp->b_error && bp->b_ops) {
1164 ASSERT(!bp->b_iodone);
1165 bp->b_ops->verify_read(bp);
1169 bp->b_flags |= XBF_DONE;
1172 (*(bp->b_iodone))(bp);
1173 else if (bp->b_flags & XBF_ASYNC)
1176 complete(&bp->b_iowait);
1181 struct work_struct *work)
1183 struct xfs_buf *bp =
1184 container_of(work, xfs_buf_t, b_ioend_work);
1190 xfs_buf_ioend_async(
1193 INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
1194 queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
1201 xfs_failaddr_t failaddr)
1203 ASSERT(error <= 0 && error >= -1000);
1204 bp->b_error = error;
1205 trace_xfs_buf_ioerror(bp, error, failaddr);
1209 xfs_buf_ioerror_alert(
1213 xfs_alert(bp->b_mount,
1214 "metadata I/O error in \"%s\" at daddr 0x%llx len %d error %d",
1215 func, (uint64_t)XFS_BUF_ADDR(bp), bp->b_length,
1225 ASSERT(xfs_buf_islocked(bp));
1227 bp->b_flags |= XBF_WRITE;
1228 bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
1229 XBF_WRITE_FAIL | XBF_DONE);
1231 error = xfs_buf_submit(bp);
1233 xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
1241 struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private;
1244 * don't overwrite existing errors - otherwise we can lose errors on
1245 * buffers that require multiple bios to complete.
1247 if (bio->bi_status) {
1248 int error = blk_status_to_errno(bio->bi_status);
1250 cmpxchg(&bp->b_io_error, 0, error);
1253 if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1254 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1256 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1257 xfs_buf_ioend_async(bp);
1262 xfs_buf_ioapply_map(
1270 int total_nr_pages = bp->b_page_count;
1273 sector_t sector = bp->b_maps[map].bm_bn;
1277 /* skip the pages in the buffer before the start offset */
1279 offset = *buf_offset;
1280 while (offset >= PAGE_SIZE) {
1282 offset -= PAGE_SIZE;
1286 * Limit the IO size to the length of the current vector, and update the
1287 * remaining IO count for the next time around.
1289 size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1291 *buf_offset += size;
1294 atomic_inc(&bp->b_io_remaining);
1295 nr_pages = min(total_nr_pages, BIO_MAX_PAGES);
1297 bio = bio_alloc(GFP_NOIO, nr_pages);
1298 bio_set_dev(bio, bp->b_target->bt_bdev);
1299 bio->bi_iter.bi_sector = sector;
1300 bio->bi_end_io = xfs_buf_bio_end_io;
1301 bio->bi_private = bp;
1304 for (; size && nr_pages; nr_pages--, page_index++) {
1305 int rbytes, nbytes = PAGE_SIZE - offset;
1310 rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
1312 if (rbytes < nbytes)
1316 sector += BTOBB(nbytes);
1321 if (likely(bio->bi_iter.bi_size)) {
1322 if (xfs_buf_is_vmapped(bp)) {
1323 flush_kernel_vmap_range(bp->b_addr,
1324 xfs_buf_vmap_len(bp));
1331 * This is guaranteed not to be the last io reference count
1332 * because the caller (xfs_buf_submit) holds a count itself.
1334 atomic_dec(&bp->b_io_remaining);
1335 xfs_buf_ioerror(bp, -EIO);
1345 struct blk_plug plug;
1352 * Make sure we capture only current IO errors rather than stale errors
1353 * left over from previous use of the buffer (e.g. failed readahead).
1357 if (bp->b_flags & XBF_WRITE) {
1361 * Run the write verifier callback function if it exists. If
1362 * this function fails it will mark the buffer with an error and
1363 * the IO should not be dispatched.
1366 bp->b_ops->verify_write(bp);
1368 xfs_force_shutdown(bp->b_mount,
1369 SHUTDOWN_CORRUPT_INCORE);
1372 } else if (bp->b_bn != XFS_BUF_DADDR_NULL) {
1373 struct xfs_mount *mp = bp->b_mount;
1376 * non-crc filesystems don't attach verifiers during
1377 * log recovery, so don't warn for such filesystems.
1379 if (xfs_sb_version_hascrc(&mp->m_sb)) {
1381 "%s: no buf ops on daddr 0x%llx len %d",
1382 __func__, bp->b_bn, bp->b_length);
1383 xfs_hex_dump(bp->b_addr,
1384 XFS_CORRUPTION_DUMP_LEN);
1390 if (bp->b_flags & XBF_READ_AHEAD)
1394 /* we only use the buffer cache for meta-data */
1398 * Walk all the vectors issuing IO on them. Set up the initial offset
1399 * into the buffer and the desired IO size before we start -
1400 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1403 offset = bp->b_offset;
1404 size = BBTOB(bp->b_length);
1405 blk_start_plug(&plug);
1406 for (i = 0; i < bp->b_map_count; i++) {
1407 xfs_buf_ioapply_map(bp, i, &offset, &size, op);
1411 break; /* all done */
1413 blk_finish_plug(&plug);
1417 * Wait for I/O completion of a sync buffer and return the I/O error code.
1423 ASSERT(!(bp->b_flags & XBF_ASYNC));
1425 trace_xfs_buf_iowait(bp, _RET_IP_);
1426 wait_for_completion(&bp->b_iowait);
1427 trace_xfs_buf_iowait_done(bp, _RET_IP_);
1433 * Buffer I/O submission path, read or write. Asynchronous submission transfers
1434 * the buffer lock ownership and the current reference to the IO. It is not
1435 * safe to reference the buffer after a call to this function unless the caller
1436 * holds an additional reference itself.
1445 trace_xfs_buf_submit(bp, _RET_IP_);
1447 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1449 /* on shutdown we stale and complete the buffer immediately */
1450 if (XFS_FORCED_SHUTDOWN(bp->b_mount)) {
1451 xfs_buf_ioerror(bp, -EIO);
1452 bp->b_flags &= ~XBF_DONE;
1459 * Grab a reference so the buffer does not go away underneath us. For
1460 * async buffers, I/O completion drops the callers reference, which
1461 * could occur before submission returns.
1465 if (bp->b_flags & XBF_WRITE)
1466 xfs_buf_wait_unpin(bp);
1468 /* clear the internal error state to avoid spurious errors */
1472 * Set the count to 1 initially, this will stop an I/O completion
1473 * callout which happens before we have started all the I/O from calling
1474 * xfs_buf_ioend too early.
1476 atomic_set(&bp->b_io_remaining, 1);
1477 if (bp->b_flags & XBF_ASYNC)
1478 xfs_buf_ioacct_inc(bp);
1479 _xfs_buf_ioapply(bp);
1482 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1483 * reference we took above. If we drop it to zero, run completion so
1484 * that we don't return to the caller with completion still pending.
1486 if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1487 if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
1490 xfs_buf_ioend_async(bp);
1494 error = xfs_buf_iowait(bp);
1497 * Release the hold that keeps the buffer referenced for the entire
1498 * I/O. Note that if the buffer is async, it is not safe to reference
1499 * after this release.
1513 return bp->b_addr + offset;
1515 offset += bp->b_offset;
1516 page = bp->b_pages[offset >> PAGE_SHIFT];
1517 return page_address(page) + (offset & (PAGE_SIZE-1));
1528 bend = boff + bsize;
1529 while (boff < bend) {
1531 int page_index, page_offset, csize;
1533 page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1534 page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1535 page = bp->b_pages[page_index];
1536 csize = min_t(size_t, PAGE_SIZE - page_offset,
1537 BBTOB(bp->b_length) - boff);
1539 ASSERT((csize + page_offset) <= PAGE_SIZE);
1541 memset(page_address(page) + page_offset, 0, csize);
1548 * Handling of buffer targets (buftargs).
1552 * Wait for any bufs with callbacks that have been submitted but have not yet
1553 * returned. These buffers will have an elevated hold count, so wait on those
1554 * while freeing all the buffers only held by the LRU.
1556 static enum lru_status
1557 xfs_buftarg_wait_rele(
1558 struct list_head *item,
1559 struct list_lru_one *lru,
1560 spinlock_t *lru_lock,
1564 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1565 struct list_head *dispose = arg;
1567 if (atomic_read(&bp->b_hold) > 1) {
1568 /* need to wait, so skip it this pass */
1569 trace_xfs_buf_wait_buftarg(bp, _RET_IP_);
1572 if (!spin_trylock(&bp->b_lock))
1576 * clear the LRU reference count so the buffer doesn't get
1577 * ignored in xfs_buf_rele().
1579 atomic_set(&bp->b_lru_ref, 0);
1580 bp->b_state |= XFS_BSTATE_DISPOSE;
1581 list_lru_isolate_move(lru, item, dispose);
1582 spin_unlock(&bp->b_lock);
1588 struct xfs_buftarg *btp)
1594 * First wait on the buftarg I/O count for all in-flight buffers to be
1595 * released. This is critical as new buffers do not make the LRU until
1596 * they are released.
1598 * Next, flush the buffer workqueue to ensure all completion processing
1599 * has finished. Just waiting on buffer locks is not sufficient for
1600 * async IO as the reference count held over IO is not released until
1601 * after the buffer lock is dropped. Hence we need to ensure here that
1602 * all reference counts have been dropped before we start walking the
1605 while (percpu_counter_sum(&btp->bt_io_count))
1607 flush_workqueue(btp->bt_mount->m_buf_workqueue);
1609 /* loop until there is nothing left on the lru list. */
1610 while (list_lru_count(&btp->bt_lru)) {
1611 list_lru_walk(&btp->bt_lru, xfs_buftarg_wait_rele,
1612 &dispose, LONG_MAX);
1614 while (!list_empty(&dispose)) {
1616 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1617 list_del_init(&bp->b_lru);
1618 if (bp->b_flags & XBF_WRITE_FAIL) {
1619 xfs_alert(btp->bt_mount,
1620 "Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
1621 (long long)bp->b_bn);
1622 xfs_alert(btp->bt_mount,
1623 "Please run xfs_repair to determine the extent of the problem.");
1632 static enum lru_status
1633 xfs_buftarg_isolate(
1634 struct list_head *item,
1635 struct list_lru_one *lru,
1636 spinlock_t *lru_lock,
1639 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1640 struct list_head *dispose = arg;
1643 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1644 * If we fail to get the lock, just skip it.
1646 if (!spin_trylock(&bp->b_lock))
1649 * Decrement the b_lru_ref count unless the value is already
1650 * zero. If the value is already zero, we need to reclaim the
1651 * buffer, otherwise it gets another trip through the LRU.
1653 if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1654 spin_unlock(&bp->b_lock);
1658 bp->b_state |= XFS_BSTATE_DISPOSE;
1659 list_lru_isolate_move(lru, item, dispose);
1660 spin_unlock(&bp->b_lock);
1664 static unsigned long
1665 xfs_buftarg_shrink_scan(
1666 struct shrinker *shrink,
1667 struct shrink_control *sc)
1669 struct xfs_buftarg *btp = container_of(shrink,
1670 struct xfs_buftarg, bt_shrinker);
1672 unsigned long freed;
1674 freed = list_lru_shrink_walk(&btp->bt_lru, sc,
1675 xfs_buftarg_isolate, &dispose);
1677 while (!list_empty(&dispose)) {
1679 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1680 list_del_init(&bp->b_lru);
1687 static unsigned long
1688 xfs_buftarg_shrink_count(
1689 struct shrinker *shrink,
1690 struct shrink_control *sc)
1692 struct xfs_buftarg *btp = container_of(shrink,
1693 struct xfs_buftarg, bt_shrinker);
1694 return list_lru_shrink_count(&btp->bt_lru, sc);
1699 struct xfs_buftarg *btp)
1701 unregister_shrinker(&btp->bt_shrinker);
1702 ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
1703 percpu_counter_destroy(&btp->bt_io_count);
1704 list_lru_destroy(&btp->bt_lru);
1706 xfs_blkdev_issue_flush(btp);
1712 xfs_setsize_buftarg(
1714 unsigned int sectorsize)
1716 /* Set up metadata sector size info */
1717 btp->bt_meta_sectorsize = sectorsize;
1718 btp->bt_meta_sectormask = sectorsize - 1;
1720 if (set_blocksize(btp->bt_bdev, sectorsize)) {
1721 xfs_warn(btp->bt_mount,
1722 "Cannot set_blocksize to %u on device %pg",
1723 sectorsize, btp->bt_bdev);
1727 /* Set up device logical sector size mask */
1728 btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);
1729 btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;
1735 * When allocating the initial buffer target we have not yet
1736 * read in the superblock, so don't know what sized sectors
1737 * are being used at this early stage. Play safe.
1740 xfs_setsize_buftarg_early(
1742 struct block_device *bdev)
1744 return xfs_setsize_buftarg(btp, bdev_logical_block_size(bdev));
1749 struct xfs_mount *mp,
1750 struct block_device *bdev,
1751 struct dax_device *dax_dev)
1755 btp = kmem_zalloc(sizeof(*btp), KM_NOFS);
1758 btp->bt_dev = bdev->bd_dev;
1759 btp->bt_bdev = bdev;
1760 btp->bt_daxdev = dax_dev;
1762 if (xfs_setsize_buftarg_early(btp, bdev))
1765 if (list_lru_init(&btp->bt_lru))
1768 if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
1771 btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
1772 btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
1773 btp->bt_shrinker.seeks = DEFAULT_SEEKS;
1774 btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
1775 if (register_shrinker(&btp->bt_shrinker))
1780 percpu_counter_destroy(&btp->bt_io_count);
1782 list_lru_destroy(&btp->bt_lru);
1789 * Cancel a delayed write list.
1791 * Remove each buffer from the list, clear the delwri queue flag and drop the
1792 * associated buffer reference.
1795 xfs_buf_delwri_cancel(
1796 struct list_head *list)
1800 while (!list_empty(list)) {
1801 bp = list_first_entry(list, struct xfs_buf, b_list);
1804 bp->b_flags &= ~_XBF_DELWRI_Q;
1805 list_del_init(&bp->b_list);
1811 * Add a buffer to the delayed write list.
1813 * This queues a buffer for writeout if it hasn't already been. Note that
1814 * neither this routine nor the buffer list submission functions perform
1815 * any internal synchronization. It is expected that the lists are thread-local
1818 * Returns true if we queued up the buffer, or false if it already had
1819 * been on the buffer list.
1822 xfs_buf_delwri_queue(
1824 struct list_head *list)
1826 ASSERT(xfs_buf_islocked(bp));
1827 ASSERT(!(bp->b_flags & XBF_READ));
1830 * If the buffer is already marked delwri it already is queued up
1831 * by someone else for imediate writeout. Just ignore it in that
1834 if (bp->b_flags & _XBF_DELWRI_Q) {
1835 trace_xfs_buf_delwri_queued(bp, _RET_IP_);
1839 trace_xfs_buf_delwri_queue(bp, _RET_IP_);
1842 * If a buffer gets written out synchronously or marked stale while it
1843 * is on a delwri list we lazily remove it. To do this, the other party
1844 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1845 * It remains referenced and on the list. In a rare corner case it
1846 * might get readded to a delwri list after the synchronous writeout, in
1847 * which case we need just need to re-add the flag here.
1849 bp->b_flags |= _XBF_DELWRI_Q;
1850 if (list_empty(&bp->b_list)) {
1851 atomic_inc(&bp->b_hold);
1852 list_add_tail(&bp->b_list, list);
1859 * Compare function is more complex than it needs to be because
1860 * the return value is only 32 bits and we are doing comparisons
1866 struct list_head *a,
1867 struct list_head *b)
1869 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
1870 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
1873 diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
1882 * Submit buffers for write. If wait_list is specified, the buffers are
1883 * submitted using sync I/O and placed on the wait list such that the caller can
1884 * iowait each buffer. Otherwise async I/O is used and the buffers are released
1885 * at I/O completion time. In either case, buffers remain locked until I/O
1886 * completes and the buffer is released from the queue.
1889 xfs_buf_delwri_submit_buffers(
1890 struct list_head *buffer_list,
1891 struct list_head *wait_list)
1893 struct xfs_buf *bp, *n;
1895 struct blk_plug plug;
1897 list_sort(NULL, buffer_list, xfs_buf_cmp);
1899 blk_start_plug(&plug);
1900 list_for_each_entry_safe(bp, n, buffer_list, b_list) {
1902 if (xfs_buf_ispinned(bp)) {
1906 if (!xfs_buf_trylock(bp))
1913 * Someone else might have written the buffer synchronously or
1914 * marked it stale in the meantime. In that case only the
1915 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1916 * reference and remove it from the list here.
1918 if (!(bp->b_flags & _XBF_DELWRI_Q)) {
1919 list_del_init(&bp->b_list);
1924 trace_xfs_buf_delwri_split(bp, _RET_IP_);
1927 * If we have a wait list, each buffer (and associated delwri
1928 * queue reference) transfers to it and is submitted
1929 * synchronously. Otherwise, drop the buffer from the delwri
1930 * queue and submit async.
1932 bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_WRITE_FAIL);
1933 bp->b_flags |= XBF_WRITE;
1935 bp->b_flags &= ~XBF_ASYNC;
1936 list_move_tail(&bp->b_list, wait_list);
1938 bp->b_flags |= XBF_ASYNC;
1939 list_del_init(&bp->b_list);
1941 __xfs_buf_submit(bp, false);
1943 blk_finish_plug(&plug);
1949 * Write out a buffer list asynchronously.
1951 * This will take the @buffer_list, write all non-locked and non-pinned buffers
1952 * out and not wait for I/O completion on any of the buffers. This interface
1953 * is only safely useable for callers that can track I/O completion by higher
1954 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
1957 * Note: this function will skip buffers it would block on, and in doing so
1958 * leaves them on @buffer_list so they can be retried on a later pass. As such,
1959 * it is up to the caller to ensure that the buffer list is fully submitted or
1960 * cancelled appropriately when they are finished with the list. Failure to
1961 * cancel or resubmit the list until it is empty will result in leaked buffers
1965 xfs_buf_delwri_submit_nowait(
1966 struct list_head *buffer_list)
1968 return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
1972 * Write out a buffer list synchronously.
1974 * This will take the @buffer_list, write all buffers out and wait for I/O
1975 * completion on all of the buffers. @buffer_list is consumed by the function,
1976 * so callers must have some other way of tracking buffers if they require such
1980 xfs_buf_delwri_submit(
1981 struct list_head *buffer_list)
1983 LIST_HEAD (wait_list);
1984 int error = 0, error2;
1987 xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);
1989 /* Wait for IO to complete. */
1990 while (!list_empty(&wait_list)) {
1991 bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
1993 list_del_init(&bp->b_list);
1996 * Wait on the locked buffer, check for errors and unlock and
1997 * release the delwri queue reference.
1999 error2 = xfs_buf_iowait(bp);
2009 * Push a single buffer on a delwri queue.
2011 * The purpose of this function is to submit a single buffer of a delwri queue
2012 * and return with the buffer still on the original queue. The waiting delwri
2013 * buffer submission infrastructure guarantees transfer of the delwri queue
2014 * buffer reference to a temporary wait list. We reuse this infrastructure to
2015 * transfer the buffer back to the original queue.
2017 * Note the buffer transitions from the queued state, to the submitted and wait
2018 * listed state and back to the queued state during this call. The buffer
2019 * locking and queue management logic between _delwri_pushbuf() and
2020 * _delwri_queue() guarantee that the buffer cannot be queued to another list
2024 xfs_buf_delwri_pushbuf(
2026 struct list_head *buffer_list)
2028 LIST_HEAD (submit_list);
2031 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
2033 trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);
2036 * Isolate the buffer to a new local list so we can submit it for I/O
2037 * independently from the rest of the original list.
2040 list_move(&bp->b_list, &submit_list);
2044 * Delwri submission clears the DELWRI_Q buffer flag and returns with
2045 * the buffer on the wait list with the original reference. Rather than
2046 * bounce the buffer from a local wait list back to the original list
2047 * after I/O completion, reuse the original list as the wait list.
2049 xfs_buf_delwri_submit_buffers(&submit_list, buffer_list);
2052 * The buffer is now locked, under I/O and wait listed on the original
2053 * delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
2054 * return with the buffer unlocked and on the original queue.
2056 error = xfs_buf_iowait(bp);
2057 bp->b_flags |= _XBF_DELWRI_Q;
2066 xfs_buf_zone = kmem_cache_create("xfs_buf",
2067 sizeof(struct xfs_buf), 0,
2068 SLAB_HWCACHE_ALIGN, NULL);
2079 xfs_buf_terminate(void)
2081 kmem_cache_destroy(xfs_buf_zone);
2084 void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
2087 * Set the lru reference count to 0 based on the error injection tag.
2088 * This allows userspace to disrupt buffer caching for debug/testing
2091 if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
2094 atomic_set(&bp->b_lru_ref, lru_ref);
2098 * Verify an on-disk magic value against the magic value specified in the
2099 * verifier structure. The verifier magic is in disk byte order so the caller is
2100 * expected to pass the value directly from disk.
2107 struct xfs_mount *mp = bp->b_mount;
2110 idx = xfs_sb_version_hascrc(&mp->m_sb);
2111 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))
2113 return dmagic == bp->b_ops->magic[idx];
2116 * Verify an on-disk magic value against the magic value specified in the
2117 * verifier structure. The verifier magic is in disk byte order so the caller is
2118 * expected to pass the value directly from disk.
2125 struct xfs_mount *mp = bp->b_mount;
2128 idx = xfs_sb_version_hascrc(&mp->m_sb);
2129 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))
2131 return dmagic == bp->b_ops->magic16[idx];