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);
201 static struct xfs_buf *
203 struct xfs_buftarg *target,
204 struct xfs_buf_map *map,
206 xfs_buf_flags_t flags)
212 bp = kmem_zone_zalloc(xfs_buf_zone, KM_NOFS);
217 * We don't want certain flags to appear in b_flags unless they are
218 * specifically set by later operations on the buffer.
220 flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
222 atomic_set(&bp->b_hold, 1);
223 atomic_set(&bp->b_lru_ref, 1);
224 init_completion(&bp->b_iowait);
225 INIT_LIST_HEAD(&bp->b_lru);
226 INIT_LIST_HEAD(&bp->b_list);
227 INIT_LIST_HEAD(&bp->b_li_list);
228 sema_init(&bp->b_sema, 0); /* held, no waiters */
229 spin_lock_init(&bp->b_lock);
230 bp->b_target = target;
231 bp->b_mount = target->bt_mount;
235 * Set length and io_length to the same value initially.
236 * I/O routines should use io_length, which will be the same in
237 * most cases but may be reset (e.g. XFS recovery).
239 error = xfs_buf_get_maps(bp, nmaps);
241 kmem_zone_free(xfs_buf_zone, bp);
245 bp->b_bn = map[0].bm_bn;
247 for (i = 0; i < nmaps; i++) {
248 bp->b_maps[i].bm_bn = map[i].bm_bn;
249 bp->b_maps[i].bm_len = map[i].bm_len;
250 bp->b_length += map[i].bm_len;
253 atomic_set(&bp->b_pin_count, 0);
254 init_waitqueue_head(&bp->b_waiters);
256 XFS_STATS_INC(bp->b_mount, xb_create);
257 trace_xfs_buf_init(bp, _RET_IP_);
263 * Allocate a page array capable of holding a specified number
264 * of pages, and point the page buf at it.
271 /* Make sure that we have a page list */
272 if (bp->b_pages == NULL) {
273 bp->b_page_count = page_count;
274 if (page_count <= XB_PAGES) {
275 bp->b_pages = bp->b_page_array;
277 bp->b_pages = kmem_alloc(sizeof(struct page *) *
278 page_count, KM_NOFS);
279 if (bp->b_pages == NULL)
282 memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
288 * Frees b_pages if it was allocated.
294 if (bp->b_pages != bp->b_page_array) {
295 kmem_free(bp->b_pages);
301 * Releases the specified buffer.
303 * The modification state of any associated pages is left unchanged.
304 * The buffer must not be on any hash - use xfs_buf_rele instead for
305 * hashed and refcounted buffers
311 trace_xfs_buf_free(bp, _RET_IP_);
313 ASSERT(list_empty(&bp->b_lru));
315 if (bp->b_flags & _XBF_PAGES) {
318 if (xfs_buf_is_vmapped(bp))
319 vm_unmap_ram(bp->b_addr - bp->b_offset,
322 for (i = 0; i < bp->b_page_count; i++) {
323 struct page *page = bp->b_pages[i];
327 } else if (bp->b_flags & _XBF_KMEM)
328 kmem_free(bp->b_addr);
329 _xfs_buf_free_pages(bp);
330 xfs_buf_free_maps(bp);
331 kmem_zone_free(xfs_buf_zone, bp);
335 * Allocates all the pages for buffer in question and builds it's page list.
338 xfs_buf_allocate_memory(
343 size_t nbytes, offset;
344 gfp_t gfp_mask = xb_to_gfp(flags);
345 unsigned short page_count, i;
346 xfs_off_t start, end;
350 * for buffers that are contained within a single page, just allocate
351 * the memory from the heap - there's no need for the complexity of
352 * page arrays to keep allocation down to order 0.
354 size = BBTOB(bp->b_length);
355 if (size < PAGE_SIZE) {
356 bp->b_addr = kmem_alloc(size, KM_NOFS);
358 /* low memory - use alloc_page loop instead */
362 if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
363 ((unsigned long)bp->b_addr & PAGE_MASK)) {
364 /* b_addr spans two pages - use alloc_page instead */
365 kmem_free(bp->b_addr);
369 bp->b_offset = offset_in_page(bp->b_addr);
370 bp->b_pages = bp->b_page_array;
371 bp->b_pages[0] = virt_to_page(bp->b_addr);
372 bp->b_page_count = 1;
373 bp->b_flags |= _XBF_KMEM;
378 start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT;
379 end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1)
381 page_count = end - start;
382 error = _xfs_buf_get_pages(bp, page_count);
386 offset = bp->b_offset;
387 bp->b_flags |= _XBF_PAGES;
389 for (i = 0; i < bp->b_page_count; i++) {
393 page = alloc_page(gfp_mask);
394 if (unlikely(page == NULL)) {
395 if (flags & XBF_READ_AHEAD) {
396 bp->b_page_count = i;
402 * This could deadlock.
404 * But until all the XFS lowlevel code is revamped to
405 * handle buffer allocation failures we can't do much.
407 if (!(++retries % 100))
409 "%s(%u) possible memory allocation deadlock in %s (mode:0x%x)",
410 current->comm, current->pid,
413 XFS_STATS_INC(bp->b_mount, xb_page_retries);
414 congestion_wait(BLK_RW_ASYNC, HZ/50);
418 XFS_STATS_INC(bp->b_mount, xb_page_found);
420 nbytes = min_t(size_t, size, PAGE_SIZE - offset);
422 bp->b_pages[i] = page;
428 for (i = 0; i < bp->b_page_count; i++)
429 __free_page(bp->b_pages[i]);
430 bp->b_flags &= ~_XBF_PAGES;
435 * Map buffer into kernel address-space if necessary.
442 ASSERT(bp->b_flags & _XBF_PAGES);
443 if (bp->b_page_count == 1) {
444 /* A single page buffer is always mappable */
445 bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
446 } else if (flags & XBF_UNMAPPED) {
453 * vm_map_ram() will allocate auxillary structures (e.g.
454 * pagetables) with GFP_KERNEL, yet we are likely to be under
455 * GFP_NOFS context here. Hence we need to tell memory reclaim
456 * that we are in such a context via PF_MEMALLOC_NOFS to prevent
457 * memory reclaim re-entering the filesystem here and
458 * potentially deadlocking.
460 nofs_flag = memalloc_nofs_save();
462 bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
467 } while (retried++ <= 1);
468 memalloc_nofs_restore(nofs_flag);
472 bp->b_addr += bp->b_offset;
479 * Finding and Reading Buffers
483 struct rhashtable_compare_arg *arg,
486 const struct xfs_buf_map *map = arg->key;
487 const struct xfs_buf *bp = obj;
490 * The key hashing in the lookup path depends on the key being the
491 * first element of the compare_arg, make sure to assert this.
493 BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
495 if (bp->b_bn != map->bm_bn)
498 if (unlikely(bp->b_length != map->bm_len)) {
500 * found a block number match. If the range doesn't
501 * match, the only way this is allowed is if the buffer
502 * in the cache is stale and the transaction that made
503 * it stale has not yet committed. i.e. we are
504 * reallocating a busy extent. Skip this buffer and
505 * continue searching for an exact match.
507 ASSERT(bp->b_flags & XBF_STALE);
513 static const struct rhashtable_params xfs_buf_hash_params = {
514 .min_size = 32, /* empty AGs have minimal footprint */
516 .key_len = sizeof(xfs_daddr_t),
517 .key_offset = offsetof(struct xfs_buf, b_bn),
518 .head_offset = offsetof(struct xfs_buf, b_rhash_head),
519 .automatic_shrinking = true,
520 .obj_cmpfn = _xfs_buf_obj_cmp,
525 struct xfs_perag *pag)
527 spin_lock_init(&pag->pag_buf_lock);
528 return rhashtable_init(&pag->pag_buf_hash, &xfs_buf_hash_params);
532 xfs_buf_hash_destroy(
533 struct xfs_perag *pag)
535 rhashtable_destroy(&pag->pag_buf_hash);
539 * Look up a buffer in the buffer cache and return it referenced and locked
542 * If @new_bp is supplied and we have a lookup miss, insert @new_bp into the
545 * If XBF_TRYLOCK is set in @flags, only try to lock the buffer and return
546 * -EAGAIN if we fail to lock it.
549 * -EFSCORRUPTED if have been supplied with an invalid address
550 * -EAGAIN on trylock failure
551 * -ENOENT if we fail to find a match and @new_bp was NULL
553 * - @new_bp if we inserted it into the cache
554 * - the buffer we found and locked.
558 struct xfs_buftarg *btp,
559 struct xfs_buf_map *map,
561 xfs_buf_flags_t flags,
562 struct xfs_buf *new_bp,
563 struct xfs_buf **found_bp)
565 struct xfs_perag *pag;
567 struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
573 for (i = 0; i < nmaps; i++)
574 cmap.bm_len += map[i].bm_len;
576 /* Check for IOs smaller than the sector size / not sector aligned */
577 ASSERT(!(BBTOB(cmap.bm_len) < btp->bt_meta_sectorsize));
578 ASSERT(!(BBTOB(cmap.bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
581 * Corrupted block numbers can get through to here, unfortunately, so we
582 * have to check that the buffer falls within the filesystem bounds.
584 eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
585 if (cmap.bm_bn < 0 || cmap.bm_bn >= eofs) {
586 xfs_alert(btp->bt_mount,
587 "%s: daddr 0x%llx out of range, EOFS 0x%llx",
588 __func__, cmap.bm_bn, eofs);
590 return -EFSCORRUPTED;
593 pag = xfs_perag_get(btp->bt_mount,
594 xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
596 spin_lock(&pag->pag_buf_lock);
597 bp = rhashtable_lookup_fast(&pag->pag_buf_hash, &cmap,
598 xfs_buf_hash_params);
600 atomic_inc(&bp->b_hold);
606 XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
607 spin_unlock(&pag->pag_buf_lock);
612 /* the buffer keeps the perag reference until it is freed */
614 rhashtable_insert_fast(&pag->pag_buf_hash, &new_bp->b_rhash_head,
615 xfs_buf_hash_params);
616 spin_unlock(&pag->pag_buf_lock);
621 spin_unlock(&pag->pag_buf_lock);
624 if (!xfs_buf_trylock(bp)) {
625 if (flags & XBF_TRYLOCK) {
627 XFS_STATS_INC(btp->bt_mount, xb_busy_locked);
631 XFS_STATS_INC(btp->bt_mount, xb_get_locked_waited);
635 * if the buffer is stale, clear all the external state associated with
636 * it. We need to keep flags such as how we allocated the buffer memory
639 if (bp->b_flags & XBF_STALE) {
640 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
641 ASSERT(bp->b_iodone == NULL);
642 bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
646 trace_xfs_buf_find(bp, flags, _RET_IP_);
647 XFS_STATS_INC(btp->bt_mount, xb_get_locked);
654 struct xfs_buftarg *target,
657 xfs_buf_flags_t flags)
661 DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
663 error = xfs_buf_find(target, &map, 1, flags, NULL, &bp);
670 * Assembles a buffer covering the specified range. The code is optimised for
671 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
672 * more hits than misses.
676 struct xfs_buftarg *target,
677 struct xfs_buf_map *map,
679 xfs_buf_flags_t flags)
682 struct xfs_buf *new_bp;
685 error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
692 /* cache hit, trylock failure, caller handles failure */
693 ASSERT(flags & XBF_TRYLOCK);
696 /* cache miss, go for insert */
701 * None of the higher layers understand failure types
702 * yet, so return NULL to signal a fatal lookup error.
707 new_bp = _xfs_buf_alloc(target, map, nmaps, flags);
708 if (unlikely(!new_bp))
711 error = xfs_buf_allocate_memory(new_bp, flags);
713 xfs_buf_free(new_bp);
717 error = xfs_buf_find(target, map, nmaps, flags, new_bp, &bp);
719 xfs_buf_free(new_bp);
724 xfs_buf_free(new_bp);
728 error = _xfs_buf_map_pages(bp, flags);
729 if (unlikely(error)) {
730 xfs_warn(target->bt_mount,
731 "%s: failed to map pagesn", __func__);
738 * Clear b_error if this is a lookup from a caller that doesn't expect
739 * valid data to be found in the buffer.
741 if (!(flags & XBF_READ))
742 xfs_buf_ioerror(bp, 0);
744 XFS_STATS_INC(target->bt_mount, xb_get);
745 trace_xfs_buf_get(bp, flags, _RET_IP_);
752 xfs_buf_flags_t flags)
754 ASSERT(!(flags & XBF_WRITE));
755 ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
757 bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD);
758 bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
760 return xfs_buf_submit(bp);
764 * Reverify a buffer found in cache without an attached ->b_ops.
766 * If the caller passed an ops structure and the buffer doesn't have ops
767 * assigned, set the ops and use it to verify the contents. If verification
768 * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
769 * already in XBF_DONE state on entry.
771 * Under normal operations, every in-core buffer is verified on read I/O
772 * completion. There are two scenarios that can lead to in-core buffers without
773 * an assigned ->b_ops. The first is during log recovery of buffers on a V4
774 * filesystem, though these buffers are purged at the end of recovery. The
775 * other is online repair, which intentionally reads with a NULL buffer ops to
776 * run several verifiers across an in-core buffer in order to establish buffer
777 * type. If repair can't establish that, the buffer will be left in memory
778 * with NULL buffer ops.
783 const struct xfs_buf_ops *ops)
785 ASSERT(bp->b_flags & XBF_DONE);
786 ASSERT(bp->b_error == 0);
788 if (!ops || bp->b_ops)
792 bp->b_ops->verify_read(bp);
794 bp->b_flags &= ~XBF_DONE;
800 struct xfs_buftarg *target,
801 struct xfs_buf_map *map,
803 xfs_buf_flags_t flags,
804 const struct xfs_buf_ops *ops)
810 bp = xfs_buf_get_map(target, map, nmaps, flags);
814 trace_xfs_buf_read(bp, flags, _RET_IP_);
816 if (!(bp->b_flags & XBF_DONE)) {
817 XFS_STATS_INC(target->bt_mount, xb_get_read);
819 _xfs_buf_read(bp, flags);
823 xfs_buf_reverify(bp, ops);
825 if (flags & XBF_ASYNC) {
827 * Read ahead call which is already satisfied,
834 /* We do not want read in the flags */
835 bp->b_flags &= ~XBF_READ;
836 ASSERT(bp->b_ops != NULL || ops == NULL);
841 * If we are not low on memory then do the readahead in a deadlock
845 xfs_buf_readahead_map(
846 struct xfs_buftarg *target,
847 struct xfs_buf_map *map,
849 const struct xfs_buf_ops *ops)
851 if (bdi_read_congested(target->bt_bdev->bd_bdi))
854 xfs_buf_read_map(target, map, nmaps,
855 XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, ops);
859 * Read an uncached buffer from disk. Allocates and returns a locked
860 * buffer containing the disk contents or nothing.
863 xfs_buf_read_uncached(
864 struct xfs_buftarg *target,
868 struct xfs_buf **bpp,
869 const struct xfs_buf_ops *ops)
875 bp = xfs_buf_get_uncached(target, numblks, flags);
879 /* set up the buffer for a read IO */
880 ASSERT(bp->b_map_count == 1);
881 bp->b_bn = XFS_BUF_DADDR_NULL; /* always null for uncached buffers */
882 bp->b_maps[0].bm_bn = daddr;
883 bp->b_flags |= XBF_READ;
888 int error = bp->b_error;
898 xfs_buf_get_uncached(
899 struct xfs_buftarg *target,
903 unsigned long page_count;
906 DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
908 /* flags might contain irrelevant bits, pass only what we care about */
909 bp = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT);
910 if (unlikely(bp == NULL))
913 page_count = PAGE_ALIGN(numblks << BBSHIFT) >> PAGE_SHIFT;
914 error = _xfs_buf_get_pages(bp, page_count);
918 for (i = 0; i < page_count; i++) {
919 bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
923 bp->b_flags |= _XBF_PAGES;
925 error = _xfs_buf_map_pages(bp, 0);
926 if (unlikely(error)) {
927 xfs_warn(target->bt_mount,
928 "%s: failed to map pages", __func__);
932 trace_xfs_buf_get_uncached(bp, _RET_IP_);
937 __free_page(bp->b_pages[i]);
938 _xfs_buf_free_pages(bp);
940 xfs_buf_free_maps(bp);
941 kmem_zone_free(xfs_buf_zone, bp);
947 * Increment reference count on buffer, to hold the buffer concurrently
948 * with another thread which may release (free) the buffer asynchronously.
949 * Must hold the buffer already to call this function.
955 trace_xfs_buf_hold(bp, _RET_IP_);
956 atomic_inc(&bp->b_hold);
960 * Release a hold on the specified buffer. If the hold count is 1, the buffer is
961 * placed on LRU or freed (depending on b_lru_ref).
967 struct xfs_perag *pag = bp->b_pag;
969 bool freebuf = false;
971 trace_xfs_buf_rele(bp, _RET_IP_);
974 ASSERT(list_empty(&bp->b_lru));
975 if (atomic_dec_and_test(&bp->b_hold)) {
976 xfs_buf_ioacct_dec(bp);
982 ASSERT(atomic_read(&bp->b_hold) > 0);
985 * We grab the b_lock here first to serialise racing xfs_buf_rele()
986 * calls. The pag_buf_lock being taken on the last reference only
987 * serialises against racing lookups in xfs_buf_find(). IOWs, the second
988 * to last reference we drop here is not serialised against the last
989 * reference until we take bp->b_lock. Hence if we don't grab b_lock
990 * first, the last "release" reference can win the race to the lock and
991 * free the buffer before the second-to-last reference is processed,
992 * leading to a use-after-free scenario.
994 spin_lock(&bp->b_lock);
995 release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock);
998 * Drop the in-flight state if the buffer is already on the LRU
999 * and it holds the only reference. This is racy because we
1000 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
1001 * ensures the decrement occurs only once per-buf.
1003 if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))
1004 __xfs_buf_ioacct_dec(bp);
1008 /* the last reference has been dropped ... */
1009 __xfs_buf_ioacct_dec(bp);
1010 if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
1012 * If the buffer is added to the LRU take a new reference to the
1013 * buffer for the LRU and clear the (now stale) dispose list
1016 if (list_lru_add(&bp->b_target->bt_lru, &bp->b_lru)) {
1017 bp->b_state &= ~XFS_BSTATE_DISPOSE;
1018 atomic_inc(&bp->b_hold);
1020 spin_unlock(&pag->pag_buf_lock);
1023 * most of the time buffers will already be removed from the
1024 * LRU, so optimise that case by checking for the
1025 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1026 * was on was the disposal list
1028 if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
1029 list_lru_del(&bp->b_target->bt_lru, &bp->b_lru);
1031 ASSERT(list_empty(&bp->b_lru));
1034 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1035 rhashtable_remove_fast(&pag->pag_buf_hash, &bp->b_rhash_head,
1036 xfs_buf_hash_params);
1037 spin_unlock(&pag->pag_buf_lock);
1043 spin_unlock(&bp->b_lock);
1051 * Lock a buffer object, if it is not already locked.
1053 * If we come across a stale, pinned, locked buffer, we know that we are
1054 * being asked to lock a buffer that has been reallocated. Because it is
1055 * pinned, we know that the log has not been pushed to disk and hence it
1056 * will still be locked. Rather than continuing to have trylock attempts
1057 * fail until someone else pushes the log, push it ourselves before
1058 * returning. This means that the xfsaild will not get stuck trying
1059 * to push on stale inode buffers.
1067 locked = down_trylock(&bp->b_sema) == 0;
1069 trace_xfs_buf_trylock(bp, _RET_IP_);
1071 trace_xfs_buf_trylock_fail(bp, _RET_IP_);
1076 * Lock a buffer object.
1078 * If we come across a stale, pinned, locked buffer, we know that we
1079 * are being asked to lock a buffer that has been reallocated. Because
1080 * it is pinned, we know that the log has not been pushed to disk and
1081 * hence it will still be locked. Rather than sleeping until someone
1082 * else pushes the log, push it ourselves before trying to get the lock.
1088 trace_xfs_buf_lock(bp, _RET_IP_);
1090 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
1091 xfs_log_force(bp->b_mount, 0);
1094 trace_xfs_buf_lock_done(bp, _RET_IP_);
1101 ASSERT(xfs_buf_islocked(bp));
1104 trace_xfs_buf_unlock(bp, _RET_IP_);
1111 DECLARE_WAITQUEUE (wait, current);
1113 if (atomic_read(&bp->b_pin_count) == 0)
1116 add_wait_queue(&bp->b_waiters, &wait);
1118 set_current_state(TASK_UNINTERRUPTIBLE);
1119 if (atomic_read(&bp->b_pin_count) == 0)
1123 remove_wait_queue(&bp->b_waiters, &wait);
1124 set_current_state(TASK_RUNNING);
1128 * Buffer Utility Routines
1135 bool read = bp->b_flags & XBF_READ;
1137 trace_xfs_buf_iodone(bp, _RET_IP_);
1139 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
1142 * Pull in IO completion errors now. We are guaranteed to be running
1143 * single threaded, so we don't need the lock to read b_io_error.
1145 if (!bp->b_error && bp->b_io_error)
1146 xfs_buf_ioerror(bp, bp->b_io_error);
1148 /* Only validate buffers that were read without errors */
1149 if (read && !bp->b_error && bp->b_ops) {
1150 ASSERT(!bp->b_iodone);
1151 bp->b_ops->verify_read(bp);
1155 bp->b_flags |= XBF_DONE;
1158 (*(bp->b_iodone))(bp);
1159 else if (bp->b_flags & XBF_ASYNC)
1162 complete(&bp->b_iowait);
1167 struct work_struct *work)
1169 struct xfs_buf *bp =
1170 container_of(work, xfs_buf_t, b_ioend_work);
1176 xfs_buf_ioend_async(
1179 INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
1180 queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
1187 xfs_failaddr_t failaddr)
1189 ASSERT(error <= 0 && error >= -1000);
1190 bp->b_error = error;
1191 trace_xfs_buf_ioerror(bp, error, failaddr);
1195 xfs_buf_ioerror_alert(
1199 xfs_alert(bp->b_mount,
1200 "metadata I/O error in \"%s\" at daddr 0x%llx len %d error %d",
1201 func, (uint64_t)XFS_BUF_ADDR(bp), bp->b_length,
1211 ASSERT(xfs_buf_islocked(bp));
1213 bp->b_flags |= XBF_WRITE;
1214 bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
1215 XBF_WRITE_FAIL | XBF_DONE);
1217 error = xfs_buf_submit(bp);
1219 xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
1227 struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private;
1230 * don't overwrite existing errors - otherwise we can lose errors on
1231 * buffers that require multiple bios to complete.
1233 if (bio->bi_status) {
1234 int error = blk_status_to_errno(bio->bi_status);
1236 cmpxchg(&bp->b_io_error, 0, error);
1239 if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1240 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1242 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1243 xfs_buf_ioend_async(bp);
1248 xfs_buf_ioapply_map(
1257 int total_nr_pages = bp->b_page_count;
1260 sector_t sector = bp->b_maps[map].bm_bn;
1264 /* skip the pages in the buffer before the start offset */
1266 offset = *buf_offset;
1267 while (offset >= PAGE_SIZE) {
1269 offset -= PAGE_SIZE;
1273 * Limit the IO size to the length of the current vector, and update the
1274 * remaining IO count for the next time around.
1276 size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1278 *buf_offset += size;
1281 atomic_inc(&bp->b_io_remaining);
1282 nr_pages = min(total_nr_pages, BIO_MAX_PAGES);
1284 bio = bio_alloc(GFP_NOIO, nr_pages);
1285 bio_set_dev(bio, bp->b_target->bt_bdev);
1286 bio->bi_iter.bi_sector = sector;
1287 bio->bi_end_io = xfs_buf_bio_end_io;
1288 bio->bi_private = bp;
1289 bio_set_op_attrs(bio, op, op_flags);
1291 for (; size && nr_pages; nr_pages--, page_index++) {
1292 int rbytes, nbytes = PAGE_SIZE - offset;
1297 rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
1299 if (rbytes < nbytes)
1303 sector += BTOBB(nbytes);
1308 if (likely(bio->bi_iter.bi_size)) {
1309 if (xfs_buf_is_vmapped(bp)) {
1310 flush_kernel_vmap_range(bp->b_addr,
1311 xfs_buf_vmap_len(bp));
1318 * This is guaranteed not to be the last io reference count
1319 * because the caller (xfs_buf_submit) holds a count itself.
1321 atomic_dec(&bp->b_io_remaining);
1322 xfs_buf_ioerror(bp, -EIO);
1332 struct blk_plug plug;
1340 * Make sure we capture only current IO errors rather than stale errors
1341 * left over from previous use of the buffer (e.g. failed readahead).
1345 if (bp->b_flags & XBF_WRITE) {
1349 * Run the write verifier callback function if it exists. If
1350 * this function fails it will mark the buffer with an error and
1351 * the IO should not be dispatched.
1354 bp->b_ops->verify_write(bp);
1356 xfs_force_shutdown(bp->b_mount,
1357 SHUTDOWN_CORRUPT_INCORE);
1360 } else if (bp->b_bn != XFS_BUF_DADDR_NULL) {
1361 struct xfs_mount *mp = bp->b_mount;
1364 * non-crc filesystems don't attach verifiers during
1365 * log recovery, so don't warn for such filesystems.
1367 if (xfs_sb_version_hascrc(&mp->m_sb)) {
1369 "%s: no buf ops on daddr 0x%llx len %d",
1370 __func__, bp->b_bn, bp->b_length);
1371 xfs_hex_dump(bp->b_addr,
1372 XFS_CORRUPTION_DUMP_LEN);
1376 } else if (bp->b_flags & XBF_READ_AHEAD) {
1378 op_flags = REQ_RAHEAD;
1383 /* we only use the buffer cache for meta-data */
1384 op_flags |= REQ_META;
1387 * Walk all the vectors issuing IO on them. Set up the initial offset
1388 * into the buffer and the desired IO size before we start -
1389 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1392 offset = bp->b_offset;
1393 size = BBTOB(bp->b_length);
1394 blk_start_plug(&plug);
1395 for (i = 0; i < bp->b_map_count; i++) {
1396 xfs_buf_ioapply_map(bp, i, &offset, &size, op, op_flags);
1400 break; /* all done */
1402 blk_finish_plug(&plug);
1406 * Wait for I/O completion of a sync buffer and return the I/O error code.
1412 ASSERT(!(bp->b_flags & XBF_ASYNC));
1414 trace_xfs_buf_iowait(bp, _RET_IP_);
1415 wait_for_completion(&bp->b_iowait);
1416 trace_xfs_buf_iowait_done(bp, _RET_IP_);
1422 * Buffer I/O submission path, read or write. Asynchronous submission transfers
1423 * the buffer lock ownership and the current reference to the IO. It is not
1424 * safe to reference the buffer after a call to this function unless the caller
1425 * holds an additional reference itself.
1434 trace_xfs_buf_submit(bp, _RET_IP_);
1436 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1438 /* on shutdown we stale and complete the buffer immediately */
1439 if (XFS_FORCED_SHUTDOWN(bp->b_mount)) {
1440 xfs_buf_ioerror(bp, -EIO);
1441 bp->b_flags &= ~XBF_DONE;
1448 * Grab a reference so the buffer does not go away underneath us. For
1449 * async buffers, I/O completion drops the callers reference, which
1450 * could occur before submission returns.
1454 if (bp->b_flags & XBF_WRITE)
1455 xfs_buf_wait_unpin(bp);
1457 /* clear the internal error state to avoid spurious errors */
1461 * Set the count to 1 initially, this will stop an I/O completion
1462 * callout which happens before we have started all the I/O from calling
1463 * xfs_buf_ioend too early.
1465 atomic_set(&bp->b_io_remaining, 1);
1466 if (bp->b_flags & XBF_ASYNC)
1467 xfs_buf_ioacct_inc(bp);
1468 _xfs_buf_ioapply(bp);
1471 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1472 * reference we took above. If we drop it to zero, run completion so
1473 * that we don't return to the caller with completion still pending.
1475 if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1476 if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
1479 xfs_buf_ioend_async(bp);
1483 error = xfs_buf_iowait(bp);
1486 * Release the hold that keeps the buffer referenced for the entire
1487 * I/O. Note that if the buffer is async, it is not safe to reference
1488 * after this release.
1502 return bp->b_addr + offset;
1504 offset += bp->b_offset;
1505 page = bp->b_pages[offset >> PAGE_SHIFT];
1506 return page_address(page) + (offset & (PAGE_SIZE-1));
1517 bend = boff + bsize;
1518 while (boff < bend) {
1520 int page_index, page_offset, csize;
1522 page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1523 page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1524 page = bp->b_pages[page_index];
1525 csize = min_t(size_t, PAGE_SIZE - page_offset,
1526 BBTOB(bp->b_length) - boff);
1528 ASSERT((csize + page_offset) <= PAGE_SIZE);
1530 memset(page_address(page) + page_offset, 0, csize);
1537 * Handling of buffer targets (buftargs).
1541 * Wait for any bufs with callbacks that have been submitted but have not yet
1542 * returned. These buffers will have an elevated hold count, so wait on those
1543 * while freeing all the buffers only held by the LRU.
1545 static enum lru_status
1546 xfs_buftarg_wait_rele(
1547 struct list_head *item,
1548 struct list_lru_one *lru,
1549 spinlock_t *lru_lock,
1553 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1554 struct list_head *dispose = arg;
1556 if (atomic_read(&bp->b_hold) > 1) {
1557 /* need to wait, so skip it this pass */
1558 trace_xfs_buf_wait_buftarg(bp, _RET_IP_);
1561 if (!spin_trylock(&bp->b_lock))
1565 * clear the LRU reference count so the buffer doesn't get
1566 * ignored in xfs_buf_rele().
1568 atomic_set(&bp->b_lru_ref, 0);
1569 bp->b_state |= XFS_BSTATE_DISPOSE;
1570 list_lru_isolate_move(lru, item, dispose);
1571 spin_unlock(&bp->b_lock);
1577 struct xfs_buftarg *btp)
1583 * First wait on the buftarg I/O count for all in-flight buffers to be
1584 * released. This is critical as new buffers do not make the LRU until
1585 * they are released.
1587 * Next, flush the buffer workqueue to ensure all completion processing
1588 * has finished. Just waiting on buffer locks is not sufficient for
1589 * async IO as the reference count held over IO is not released until
1590 * after the buffer lock is dropped. Hence we need to ensure here that
1591 * all reference counts have been dropped before we start walking the
1594 while (percpu_counter_sum(&btp->bt_io_count))
1596 flush_workqueue(btp->bt_mount->m_buf_workqueue);
1598 /* loop until there is nothing left on the lru list. */
1599 while (list_lru_count(&btp->bt_lru)) {
1600 list_lru_walk(&btp->bt_lru, xfs_buftarg_wait_rele,
1601 &dispose, LONG_MAX);
1603 while (!list_empty(&dispose)) {
1605 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1606 list_del_init(&bp->b_lru);
1607 if (bp->b_flags & XBF_WRITE_FAIL) {
1608 xfs_alert(btp->bt_mount,
1609 "Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
1610 (long long)bp->b_bn);
1611 xfs_alert(btp->bt_mount,
1612 "Please run xfs_repair to determine the extent of the problem.");
1621 static enum lru_status
1622 xfs_buftarg_isolate(
1623 struct list_head *item,
1624 struct list_lru_one *lru,
1625 spinlock_t *lru_lock,
1628 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1629 struct list_head *dispose = arg;
1632 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1633 * If we fail to get the lock, just skip it.
1635 if (!spin_trylock(&bp->b_lock))
1638 * Decrement the b_lru_ref count unless the value is already
1639 * zero. If the value is already zero, we need to reclaim the
1640 * buffer, otherwise it gets another trip through the LRU.
1642 if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1643 spin_unlock(&bp->b_lock);
1647 bp->b_state |= XFS_BSTATE_DISPOSE;
1648 list_lru_isolate_move(lru, item, dispose);
1649 spin_unlock(&bp->b_lock);
1653 static unsigned long
1654 xfs_buftarg_shrink_scan(
1655 struct shrinker *shrink,
1656 struct shrink_control *sc)
1658 struct xfs_buftarg *btp = container_of(shrink,
1659 struct xfs_buftarg, bt_shrinker);
1661 unsigned long freed;
1663 freed = list_lru_shrink_walk(&btp->bt_lru, sc,
1664 xfs_buftarg_isolate, &dispose);
1666 while (!list_empty(&dispose)) {
1668 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1669 list_del_init(&bp->b_lru);
1676 static unsigned long
1677 xfs_buftarg_shrink_count(
1678 struct shrinker *shrink,
1679 struct shrink_control *sc)
1681 struct xfs_buftarg *btp = container_of(shrink,
1682 struct xfs_buftarg, bt_shrinker);
1683 return list_lru_shrink_count(&btp->bt_lru, sc);
1688 struct xfs_buftarg *btp)
1690 unregister_shrinker(&btp->bt_shrinker);
1691 ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
1692 percpu_counter_destroy(&btp->bt_io_count);
1693 list_lru_destroy(&btp->bt_lru);
1695 xfs_blkdev_issue_flush(btp);
1701 xfs_setsize_buftarg(
1703 unsigned int sectorsize)
1705 /* Set up metadata sector size info */
1706 btp->bt_meta_sectorsize = sectorsize;
1707 btp->bt_meta_sectormask = sectorsize - 1;
1709 if (set_blocksize(btp->bt_bdev, sectorsize)) {
1710 xfs_warn(btp->bt_mount,
1711 "Cannot set_blocksize to %u on device %pg",
1712 sectorsize, btp->bt_bdev);
1716 /* Set up device logical sector size mask */
1717 btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);
1718 btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;
1724 * When allocating the initial buffer target we have not yet
1725 * read in the superblock, so don't know what sized sectors
1726 * are being used at this early stage. Play safe.
1729 xfs_setsize_buftarg_early(
1731 struct block_device *bdev)
1733 return xfs_setsize_buftarg(btp, bdev_logical_block_size(bdev));
1738 struct xfs_mount *mp,
1739 struct block_device *bdev,
1740 struct dax_device *dax_dev)
1744 btp = kmem_zalloc(sizeof(*btp), KM_SLEEP | KM_NOFS);
1747 btp->bt_dev = bdev->bd_dev;
1748 btp->bt_bdev = bdev;
1749 btp->bt_daxdev = dax_dev;
1751 if (xfs_setsize_buftarg_early(btp, bdev))
1754 if (list_lru_init(&btp->bt_lru))
1757 if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
1760 btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
1761 btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
1762 btp->bt_shrinker.seeks = DEFAULT_SEEKS;
1763 btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
1764 if (register_shrinker(&btp->bt_shrinker))
1769 percpu_counter_destroy(&btp->bt_io_count);
1771 list_lru_destroy(&btp->bt_lru);
1778 * Cancel a delayed write list.
1780 * Remove each buffer from the list, clear the delwri queue flag and drop the
1781 * associated buffer reference.
1784 xfs_buf_delwri_cancel(
1785 struct list_head *list)
1789 while (!list_empty(list)) {
1790 bp = list_first_entry(list, struct xfs_buf, b_list);
1793 bp->b_flags &= ~_XBF_DELWRI_Q;
1794 list_del_init(&bp->b_list);
1800 * Add a buffer to the delayed write list.
1802 * This queues a buffer for writeout if it hasn't already been. Note that
1803 * neither this routine nor the buffer list submission functions perform
1804 * any internal synchronization. It is expected that the lists are thread-local
1807 * Returns true if we queued up the buffer, or false if it already had
1808 * been on the buffer list.
1811 xfs_buf_delwri_queue(
1813 struct list_head *list)
1815 ASSERT(xfs_buf_islocked(bp));
1816 ASSERT(!(bp->b_flags & XBF_READ));
1819 * If the buffer is already marked delwri it already is queued up
1820 * by someone else for imediate writeout. Just ignore it in that
1823 if (bp->b_flags & _XBF_DELWRI_Q) {
1824 trace_xfs_buf_delwri_queued(bp, _RET_IP_);
1828 trace_xfs_buf_delwri_queue(bp, _RET_IP_);
1831 * If a buffer gets written out synchronously or marked stale while it
1832 * is on a delwri list we lazily remove it. To do this, the other party
1833 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1834 * It remains referenced and on the list. In a rare corner case it
1835 * might get readded to a delwri list after the synchronous writeout, in
1836 * which case we need just need to re-add the flag here.
1838 bp->b_flags |= _XBF_DELWRI_Q;
1839 if (list_empty(&bp->b_list)) {
1840 atomic_inc(&bp->b_hold);
1841 list_add_tail(&bp->b_list, list);
1848 * Compare function is more complex than it needs to be because
1849 * the return value is only 32 bits and we are doing comparisons
1855 struct list_head *a,
1856 struct list_head *b)
1858 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
1859 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
1862 diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
1871 * Submit buffers for write. If wait_list is specified, the buffers are
1872 * submitted using sync I/O and placed on the wait list such that the caller can
1873 * iowait each buffer. Otherwise async I/O is used and the buffers are released
1874 * at I/O completion time. In either case, buffers remain locked until I/O
1875 * completes and the buffer is released from the queue.
1878 xfs_buf_delwri_submit_buffers(
1879 struct list_head *buffer_list,
1880 struct list_head *wait_list)
1882 struct xfs_buf *bp, *n;
1884 struct blk_plug plug;
1886 list_sort(NULL, buffer_list, xfs_buf_cmp);
1888 blk_start_plug(&plug);
1889 list_for_each_entry_safe(bp, n, buffer_list, b_list) {
1891 if (xfs_buf_ispinned(bp)) {
1895 if (!xfs_buf_trylock(bp))
1902 * Someone else might have written the buffer synchronously or
1903 * marked it stale in the meantime. In that case only the
1904 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1905 * reference and remove it from the list here.
1907 if (!(bp->b_flags & _XBF_DELWRI_Q)) {
1908 list_del_init(&bp->b_list);
1913 trace_xfs_buf_delwri_split(bp, _RET_IP_);
1916 * If we have a wait list, each buffer (and associated delwri
1917 * queue reference) transfers to it and is submitted
1918 * synchronously. Otherwise, drop the buffer from the delwri
1919 * queue and submit async.
1921 bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_WRITE_FAIL);
1922 bp->b_flags |= XBF_WRITE;
1924 bp->b_flags &= ~XBF_ASYNC;
1925 list_move_tail(&bp->b_list, wait_list);
1927 bp->b_flags |= XBF_ASYNC;
1928 list_del_init(&bp->b_list);
1930 __xfs_buf_submit(bp, false);
1932 blk_finish_plug(&plug);
1938 * Write out a buffer list asynchronously.
1940 * This will take the @buffer_list, write all non-locked and non-pinned buffers
1941 * out and not wait for I/O completion on any of the buffers. This interface
1942 * is only safely useable for callers that can track I/O completion by higher
1943 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
1946 * Note: this function will skip buffers it would block on, and in doing so
1947 * leaves them on @buffer_list so they can be retried on a later pass. As such,
1948 * it is up to the caller to ensure that the buffer list is fully submitted or
1949 * cancelled appropriately when they are finished with the list. Failure to
1950 * cancel or resubmit the list until it is empty will result in leaked buffers
1954 xfs_buf_delwri_submit_nowait(
1955 struct list_head *buffer_list)
1957 return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
1961 * Write out a buffer list synchronously.
1963 * This will take the @buffer_list, write all buffers out and wait for I/O
1964 * completion on all of the buffers. @buffer_list is consumed by the function,
1965 * so callers must have some other way of tracking buffers if they require such
1969 xfs_buf_delwri_submit(
1970 struct list_head *buffer_list)
1972 LIST_HEAD (wait_list);
1973 int error = 0, error2;
1976 xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);
1978 /* Wait for IO to complete. */
1979 while (!list_empty(&wait_list)) {
1980 bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
1982 list_del_init(&bp->b_list);
1985 * Wait on the locked buffer, check for errors and unlock and
1986 * release the delwri queue reference.
1988 error2 = xfs_buf_iowait(bp);
1998 * Push a single buffer on a delwri queue.
2000 * The purpose of this function is to submit a single buffer of a delwri queue
2001 * and return with the buffer still on the original queue. The waiting delwri
2002 * buffer submission infrastructure guarantees transfer of the delwri queue
2003 * buffer reference to a temporary wait list. We reuse this infrastructure to
2004 * transfer the buffer back to the original queue.
2006 * Note the buffer transitions from the queued state, to the submitted and wait
2007 * listed state and back to the queued state during this call. The buffer
2008 * locking and queue management logic between _delwri_pushbuf() and
2009 * _delwri_queue() guarantee that the buffer cannot be queued to another list
2013 xfs_buf_delwri_pushbuf(
2015 struct list_head *buffer_list)
2017 LIST_HEAD (submit_list);
2020 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
2022 trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);
2025 * Isolate the buffer to a new local list so we can submit it for I/O
2026 * independently from the rest of the original list.
2029 list_move(&bp->b_list, &submit_list);
2033 * Delwri submission clears the DELWRI_Q buffer flag and returns with
2034 * the buffer on the wait list with the original reference. Rather than
2035 * bounce the buffer from a local wait list back to the original list
2036 * after I/O completion, reuse the original list as the wait list.
2038 xfs_buf_delwri_submit_buffers(&submit_list, buffer_list);
2041 * The buffer is now locked, under I/O and wait listed on the original
2042 * delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
2043 * return with the buffer unlocked and on the original queue.
2045 error = xfs_buf_iowait(bp);
2046 bp->b_flags |= _XBF_DELWRI_Q;
2055 xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
2056 KM_ZONE_HWALIGN, NULL);
2067 xfs_buf_terminate(void)
2069 kmem_zone_destroy(xfs_buf_zone);
2072 void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
2075 * Set the lru reference count to 0 based on the error injection tag.
2076 * This allows userspace to disrupt buffer caching for debug/testing
2079 if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
2082 atomic_set(&bp->b_lru_ref, lru_ref);
2086 * Verify an on-disk magic value against the magic value specified in the
2087 * verifier structure. The verifier magic is in disk byte order so the caller is
2088 * expected to pass the value directly from disk.
2095 struct xfs_mount *mp = bp->b_mount;
2098 idx = xfs_sb_version_hascrc(&mp->m_sb);
2099 if (unlikely(WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx])))
2101 return dmagic == bp->b_ops->magic[idx];
2104 * Verify an on-disk magic value against the magic value specified in the
2105 * verifier structure. The verifier magic is in disk byte order so the caller is
2106 * expected to pass the value directly from disk.
2113 struct xfs_mount *mp = bp->b_mount;
2116 idx = xfs_sb_version_hascrc(&mp->m_sb);
2117 if (unlikely(WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx])))
2119 return dmagic == bp->b_ops->magic16[idx];