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,
694 struct xfs_buf **bpp)
697 struct xfs_buf *new_bp;
701 error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
704 if (error != -ENOENT)
707 error = _xfs_buf_alloc(target, map, nmaps, flags, &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_);
753 xfs_buf_flags_t flags)
755 ASSERT(!(flags & XBF_WRITE));
756 ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
758 bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD);
759 bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
761 return xfs_buf_submit(bp);
765 * Reverify a buffer found in cache without an attached ->b_ops.
767 * If the caller passed an ops structure and the buffer doesn't have ops
768 * assigned, set the ops and use it to verify the contents. If verification
769 * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
770 * already in XBF_DONE state on entry.
772 * Under normal operations, every in-core buffer is verified on read I/O
773 * completion. There are two scenarios that can lead to in-core buffers without
774 * an assigned ->b_ops. The first is during log recovery of buffers on a V4
775 * filesystem, though these buffers are purged at the end of recovery. The
776 * other is online repair, which intentionally reads with a NULL buffer ops to
777 * run several verifiers across an in-core buffer in order to establish buffer
778 * type. If repair can't establish that, the buffer will be left in memory
779 * with NULL buffer ops.
784 const struct xfs_buf_ops *ops)
786 ASSERT(bp->b_flags & XBF_DONE);
787 ASSERT(bp->b_error == 0);
789 if (!ops || bp->b_ops)
793 bp->b_ops->verify_read(bp);
795 bp->b_flags &= ~XBF_DONE;
801 struct xfs_buftarg *target,
802 struct xfs_buf_map *map,
804 xfs_buf_flags_t flags,
805 struct xfs_buf **bpp,
806 const struct xfs_buf_ops *ops)
814 error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
818 trace_xfs_buf_read(bp, flags, _RET_IP_);
820 if (!(bp->b_flags & XBF_DONE)) {
821 /* Initiate the buffer read and wait. */
822 XFS_STATS_INC(target->bt_mount, xb_get_read);
824 error = _xfs_buf_read(bp, flags);
826 /* Readahead iodone already dropped the buffer, so exit. */
827 if (flags & XBF_ASYNC)
830 /* Buffer already read; all we need to do is check it. */
831 error = xfs_buf_reverify(bp, ops);
833 /* Readahead already finished; drop the buffer and exit. */
834 if (flags & XBF_ASYNC) {
839 /* We do not want read in the flags */
840 bp->b_flags &= ~XBF_READ;
841 ASSERT(bp->b_ops != NULL || ops == NULL);
845 * If we've had a read error, then the contents of the buffer are
846 * invalid and should not be used. To ensure that a followup read tries
847 * to pull the buffer from disk again, we clear the XBF_DONE flag and
848 * mark the buffer stale. This ensures that anyone who has a current
849 * reference to the buffer will interpret it's contents correctly and
850 * future cache lookups will also treat it as an empty, uninitialised
854 if (!XFS_FORCED_SHUTDOWN(target->bt_mount))
855 xfs_buf_ioerror_alert(bp, __func__);
857 bp->b_flags &= ~XBF_DONE;
861 /* bad CRC means corrupted metadata */
862 if (error == -EFSBADCRC)
863 error = -EFSCORRUPTED;
872 * If we are not low on memory then do the readahead in a deadlock
876 xfs_buf_readahead_map(
877 struct xfs_buftarg *target,
878 struct xfs_buf_map *map,
880 const struct xfs_buf_ops *ops)
884 if (bdi_read_congested(target->bt_bdev->bd_bdi))
887 xfs_buf_read_map(target, map, nmaps,
888 XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops);
892 * Read an uncached buffer from disk. Allocates and returns a locked
893 * buffer containing the disk contents or nothing.
896 xfs_buf_read_uncached(
897 struct xfs_buftarg *target,
901 struct xfs_buf **bpp,
902 const struct xfs_buf_ops *ops)
908 bp = xfs_buf_get_uncached(target, numblks, flags);
912 /* set up the buffer for a read IO */
913 ASSERT(bp->b_map_count == 1);
914 bp->b_bn = XFS_BUF_DADDR_NULL; /* always null for uncached buffers */
915 bp->b_maps[0].bm_bn = daddr;
916 bp->b_flags |= XBF_READ;
921 int error = bp->b_error;
931 xfs_buf_get_uncached(
932 struct xfs_buftarg *target,
936 unsigned long page_count;
939 DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
941 /* flags might contain irrelevant bits, pass only what we care about */
942 error = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT, &bp);
946 page_count = PAGE_ALIGN(numblks << BBSHIFT) >> PAGE_SHIFT;
947 error = _xfs_buf_get_pages(bp, page_count);
951 for (i = 0; i < page_count; i++) {
952 bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
956 bp->b_flags |= _XBF_PAGES;
958 error = _xfs_buf_map_pages(bp, 0);
959 if (unlikely(error)) {
960 xfs_warn(target->bt_mount,
961 "%s: failed to map pages", __func__);
965 trace_xfs_buf_get_uncached(bp, _RET_IP_);
970 __free_page(bp->b_pages[i]);
971 _xfs_buf_free_pages(bp);
973 xfs_buf_free_maps(bp);
974 kmem_cache_free(xfs_buf_zone, bp);
980 * Increment reference count on buffer, to hold the buffer concurrently
981 * with another thread which may release (free) the buffer asynchronously.
982 * Must hold the buffer already to call this function.
988 trace_xfs_buf_hold(bp, _RET_IP_);
989 atomic_inc(&bp->b_hold);
993 * Release a hold on the specified buffer. If the hold count is 1, the buffer is
994 * placed on LRU or freed (depending on b_lru_ref).
1000 struct xfs_perag *pag = bp->b_pag;
1002 bool freebuf = false;
1004 trace_xfs_buf_rele(bp, _RET_IP_);
1007 ASSERT(list_empty(&bp->b_lru));
1008 if (atomic_dec_and_test(&bp->b_hold)) {
1009 xfs_buf_ioacct_dec(bp);
1015 ASSERT(atomic_read(&bp->b_hold) > 0);
1018 * We grab the b_lock here first to serialise racing xfs_buf_rele()
1019 * calls. The pag_buf_lock being taken on the last reference only
1020 * serialises against racing lookups in xfs_buf_find(). IOWs, the second
1021 * to last reference we drop here is not serialised against the last
1022 * reference until we take bp->b_lock. Hence if we don't grab b_lock
1023 * first, the last "release" reference can win the race to the lock and
1024 * free the buffer before the second-to-last reference is processed,
1025 * leading to a use-after-free scenario.
1027 spin_lock(&bp->b_lock);
1028 release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock);
1031 * Drop the in-flight state if the buffer is already on the LRU
1032 * and it holds the only reference. This is racy because we
1033 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
1034 * ensures the decrement occurs only once per-buf.
1036 if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))
1037 __xfs_buf_ioacct_dec(bp);
1041 /* the last reference has been dropped ... */
1042 __xfs_buf_ioacct_dec(bp);
1043 if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
1045 * If the buffer is added to the LRU take a new reference to the
1046 * buffer for the LRU and clear the (now stale) dispose list
1049 if (list_lru_add(&bp->b_target->bt_lru, &bp->b_lru)) {
1050 bp->b_state &= ~XFS_BSTATE_DISPOSE;
1051 atomic_inc(&bp->b_hold);
1053 spin_unlock(&pag->pag_buf_lock);
1056 * most of the time buffers will already be removed from the
1057 * LRU, so optimise that case by checking for the
1058 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1059 * was on was the disposal list
1061 if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
1062 list_lru_del(&bp->b_target->bt_lru, &bp->b_lru);
1064 ASSERT(list_empty(&bp->b_lru));
1067 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1068 rhashtable_remove_fast(&pag->pag_buf_hash, &bp->b_rhash_head,
1069 xfs_buf_hash_params);
1070 spin_unlock(&pag->pag_buf_lock);
1076 spin_unlock(&bp->b_lock);
1084 * Lock a buffer object, if it is not already locked.
1086 * If we come across a stale, pinned, locked buffer, we know that we are
1087 * being asked to lock a buffer that has been reallocated. Because it is
1088 * pinned, we know that the log has not been pushed to disk and hence it
1089 * will still be locked. Rather than continuing to have trylock attempts
1090 * fail until someone else pushes the log, push it ourselves before
1091 * returning. This means that the xfsaild will not get stuck trying
1092 * to push on stale inode buffers.
1100 locked = down_trylock(&bp->b_sema) == 0;
1102 trace_xfs_buf_trylock(bp, _RET_IP_);
1104 trace_xfs_buf_trylock_fail(bp, _RET_IP_);
1109 * Lock a buffer object.
1111 * If we come across a stale, pinned, locked buffer, we know that we
1112 * are being asked to lock a buffer that has been reallocated. Because
1113 * it is pinned, we know that the log has not been pushed to disk and
1114 * hence it will still be locked. Rather than sleeping until someone
1115 * else pushes the log, push it ourselves before trying to get the lock.
1121 trace_xfs_buf_lock(bp, _RET_IP_);
1123 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
1124 xfs_log_force(bp->b_mount, 0);
1127 trace_xfs_buf_lock_done(bp, _RET_IP_);
1134 ASSERT(xfs_buf_islocked(bp));
1137 trace_xfs_buf_unlock(bp, _RET_IP_);
1144 DECLARE_WAITQUEUE (wait, current);
1146 if (atomic_read(&bp->b_pin_count) == 0)
1149 add_wait_queue(&bp->b_waiters, &wait);
1151 set_current_state(TASK_UNINTERRUPTIBLE);
1152 if (atomic_read(&bp->b_pin_count) == 0)
1156 remove_wait_queue(&bp->b_waiters, &wait);
1157 set_current_state(TASK_RUNNING);
1161 * Buffer Utility Routines
1168 bool read = bp->b_flags & XBF_READ;
1170 trace_xfs_buf_iodone(bp, _RET_IP_);
1172 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
1175 * Pull in IO completion errors now. We are guaranteed to be running
1176 * single threaded, so we don't need the lock to read b_io_error.
1178 if (!bp->b_error && bp->b_io_error)
1179 xfs_buf_ioerror(bp, bp->b_io_error);
1181 /* Only validate buffers that were read without errors */
1182 if (read && !bp->b_error && bp->b_ops) {
1183 ASSERT(!bp->b_iodone);
1184 bp->b_ops->verify_read(bp);
1188 bp->b_flags |= XBF_DONE;
1191 (*(bp->b_iodone))(bp);
1192 else if (bp->b_flags & XBF_ASYNC)
1195 complete(&bp->b_iowait);
1200 struct work_struct *work)
1202 struct xfs_buf *bp =
1203 container_of(work, xfs_buf_t, b_ioend_work);
1209 xfs_buf_ioend_async(
1212 INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
1213 queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
1220 xfs_failaddr_t failaddr)
1222 ASSERT(error <= 0 && error >= -1000);
1223 bp->b_error = error;
1224 trace_xfs_buf_ioerror(bp, error, failaddr);
1228 xfs_buf_ioerror_alert(
1232 xfs_alert(bp->b_mount,
1233 "metadata I/O error in \"%s\" at daddr 0x%llx len %d error %d",
1234 func, (uint64_t)XFS_BUF_ADDR(bp), bp->b_length,
1244 ASSERT(xfs_buf_islocked(bp));
1246 bp->b_flags |= XBF_WRITE;
1247 bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
1248 XBF_WRITE_FAIL | XBF_DONE);
1250 error = xfs_buf_submit(bp);
1252 xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
1260 struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private;
1263 * don't overwrite existing errors - otherwise we can lose errors on
1264 * buffers that require multiple bios to complete.
1266 if (bio->bi_status) {
1267 int error = blk_status_to_errno(bio->bi_status);
1269 cmpxchg(&bp->b_io_error, 0, error);
1272 if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1273 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1275 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1276 xfs_buf_ioend_async(bp);
1281 xfs_buf_ioapply_map(
1289 int total_nr_pages = bp->b_page_count;
1292 sector_t sector = bp->b_maps[map].bm_bn;
1296 /* skip the pages in the buffer before the start offset */
1298 offset = *buf_offset;
1299 while (offset >= PAGE_SIZE) {
1301 offset -= PAGE_SIZE;
1305 * Limit the IO size to the length of the current vector, and update the
1306 * remaining IO count for the next time around.
1308 size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1310 *buf_offset += size;
1313 atomic_inc(&bp->b_io_remaining);
1314 nr_pages = min(total_nr_pages, BIO_MAX_PAGES);
1316 bio = bio_alloc(GFP_NOIO, nr_pages);
1317 bio_set_dev(bio, bp->b_target->bt_bdev);
1318 bio->bi_iter.bi_sector = sector;
1319 bio->bi_end_io = xfs_buf_bio_end_io;
1320 bio->bi_private = bp;
1323 for (; size && nr_pages; nr_pages--, page_index++) {
1324 int rbytes, nbytes = PAGE_SIZE - offset;
1329 rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
1331 if (rbytes < nbytes)
1335 sector += BTOBB(nbytes);
1340 if (likely(bio->bi_iter.bi_size)) {
1341 if (xfs_buf_is_vmapped(bp)) {
1342 flush_kernel_vmap_range(bp->b_addr,
1343 xfs_buf_vmap_len(bp));
1350 * This is guaranteed not to be the last io reference count
1351 * because the caller (xfs_buf_submit) holds a count itself.
1353 atomic_dec(&bp->b_io_remaining);
1354 xfs_buf_ioerror(bp, -EIO);
1364 struct blk_plug plug;
1371 * Make sure we capture only current IO errors rather than stale errors
1372 * left over from previous use of the buffer (e.g. failed readahead).
1376 if (bp->b_flags & XBF_WRITE) {
1380 * Run the write verifier callback function if it exists. If
1381 * this function fails it will mark the buffer with an error and
1382 * the IO should not be dispatched.
1385 bp->b_ops->verify_write(bp);
1387 xfs_force_shutdown(bp->b_mount,
1388 SHUTDOWN_CORRUPT_INCORE);
1391 } else if (bp->b_bn != XFS_BUF_DADDR_NULL) {
1392 struct xfs_mount *mp = bp->b_mount;
1395 * non-crc filesystems don't attach verifiers during
1396 * log recovery, so don't warn for such filesystems.
1398 if (xfs_sb_version_hascrc(&mp->m_sb)) {
1400 "%s: no buf ops on daddr 0x%llx len %d",
1401 __func__, bp->b_bn, bp->b_length);
1402 xfs_hex_dump(bp->b_addr,
1403 XFS_CORRUPTION_DUMP_LEN);
1409 if (bp->b_flags & XBF_READ_AHEAD)
1413 /* we only use the buffer cache for meta-data */
1417 * Walk all the vectors issuing IO on them. Set up the initial offset
1418 * into the buffer and the desired IO size before we start -
1419 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1422 offset = bp->b_offset;
1423 size = BBTOB(bp->b_length);
1424 blk_start_plug(&plug);
1425 for (i = 0; i < bp->b_map_count; i++) {
1426 xfs_buf_ioapply_map(bp, i, &offset, &size, op);
1430 break; /* all done */
1432 blk_finish_plug(&plug);
1436 * Wait for I/O completion of a sync buffer and return the I/O error code.
1442 ASSERT(!(bp->b_flags & XBF_ASYNC));
1444 trace_xfs_buf_iowait(bp, _RET_IP_);
1445 wait_for_completion(&bp->b_iowait);
1446 trace_xfs_buf_iowait_done(bp, _RET_IP_);
1452 * Buffer I/O submission path, read or write. Asynchronous submission transfers
1453 * the buffer lock ownership and the current reference to the IO. It is not
1454 * safe to reference the buffer after a call to this function unless the caller
1455 * holds an additional reference itself.
1464 trace_xfs_buf_submit(bp, _RET_IP_);
1466 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1468 /* on shutdown we stale and complete the buffer immediately */
1469 if (XFS_FORCED_SHUTDOWN(bp->b_mount)) {
1470 xfs_buf_ioerror(bp, -EIO);
1471 bp->b_flags &= ~XBF_DONE;
1478 * Grab a reference so the buffer does not go away underneath us. For
1479 * async buffers, I/O completion drops the callers reference, which
1480 * could occur before submission returns.
1484 if (bp->b_flags & XBF_WRITE)
1485 xfs_buf_wait_unpin(bp);
1487 /* clear the internal error state to avoid spurious errors */
1491 * Set the count to 1 initially, this will stop an I/O completion
1492 * callout which happens before we have started all the I/O from calling
1493 * xfs_buf_ioend too early.
1495 atomic_set(&bp->b_io_remaining, 1);
1496 if (bp->b_flags & XBF_ASYNC)
1497 xfs_buf_ioacct_inc(bp);
1498 _xfs_buf_ioapply(bp);
1501 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1502 * reference we took above. If we drop it to zero, run completion so
1503 * that we don't return to the caller with completion still pending.
1505 if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1506 if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
1509 xfs_buf_ioend_async(bp);
1513 error = xfs_buf_iowait(bp);
1516 * Release the hold that keeps the buffer referenced for the entire
1517 * I/O. Note that if the buffer is async, it is not safe to reference
1518 * after this release.
1532 return bp->b_addr + offset;
1534 offset += bp->b_offset;
1535 page = bp->b_pages[offset >> PAGE_SHIFT];
1536 return page_address(page) + (offset & (PAGE_SIZE-1));
1547 bend = boff + bsize;
1548 while (boff < bend) {
1550 int page_index, page_offset, csize;
1552 page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1553 page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1554 page = bp->b_pages[page_index];
1555 csize = min_t(size_t, PAGE_SIZE - page_offset,
1556 BBTOB(bp->b_length) - boff);
1558 ASSERT((csize + page_offset) <= PAGE_SIZE);
1560 memset(page_address(page) + page_offset, 0, csize);
1567 * Handling of buffer targets (buftargs).
1571 * Wait for any bufs with callbacks that have been submitted but have not yet
1572 * returned. These buffers will have an elevated hold count, so wait on those
1573 * while freeing all the buffers only held by the LRU.
1575 static enum lru_status
1576 xfs_buftarg_wait_rele(
1577 struct list_head *item,
1578 struct list_lru_one *lru,
1579 spinlock_t *lru_lock,
1583 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1584 struct list_head *dispose = arg;
1586 if (atomic_read(&bp->b_hold) > 1) {
1587 /* need to wait, so skip it this pass */
1588 trace_xfs_buf_wait_buftarg(bp, _RET_IP_);
1591 if (!spin_trylock(&bp->b_lock))
1595 * clear the LRU reference count so the buffer doesn't get
1596 * ignored in xfs_buf_rele().
1598 atomic_set(&bp->b_lru_ref, 0);
1599 bp->b_state |= XFS_BSTATE_DISPOSE;
1600 list_lru_isolate_move(lru, item, dispose);
1601 spin_unlock(&bp->b_lock);
1607 struct xfs_buftarg *btp)
1613 * First wait on the buftarg I/O count for all in-flight buffers to be
1614 * released. This is critical as new buffers do not make the LRU until
1615 * they are released.
1617 * Next, flush the buffer workqueue to ensure all completion processing
1618 * has finished. Just waiting on buffer locks is not sufficient for
1619 * async IO as the reference count held over IO is not released until
1620 * after the buffer lock is dropped. Hence we need to ensure here that
1621 * all reference counts have been dropped before we start walking the
1624 while (percpu_counter_sum(&btp->bt_io_count))
1626 flush_workqueue(btp->bt_mount->m_buf_workqueue);
1628 /* loop until there is nothing left on the lru list. */
1629 while (list_lru_count(&btp->bt_lru)) {
1630 list_lru_walk(&btp->bt_lru, xfs_buftarg_wait_rele,
1631 &dispose, LONG_MAX);
1633 while (!list_empty(&dispose)) {
1635 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1636 list_del_init(&bp->b_lru);
1637 if (bp->b_flags & XBF_WRITE_FAIL) {
1638 xfs_alert(btp->bt_mount,
1639 "Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
1640 (long long)bp->b_bn);
1641 xfs_alert(btp->bt_mount,
1642 "Please run xfs_repair to determine the extent of the problem.");
1651 static enum lru_status
1652 xfs_buftarg_isolate(
1653 struct list_head *item,
1654 struct list_lru_one *lru,
1655 spinlock_t *lru_lock,
1658 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1659 struct list_head *dispose = arg;
1662 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1663 * If we fail to get the lock, just skip it.
1665 if (!spin_trylock(&bp->b_lock))
1668 * Decrement the b_lru_ref count unless the value is already
1669 * zero. If the value is already zero, we need to reclaim the
1670 * buffer, otherwise it gets another trip through the LRU.
1672 if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1673 spin_unlock(&bp->b_lock);
1677 bp->b_state |= XFS_BSTATE_DISPOSE;
1678 list_lru_isolate_move(lru, item, dispose);
1679 spin_unlock(&bp->b_lock);
1683 static unsigned long
1684 xfs_buftarg_shrink_scan(
1685 struct shrinker *shrink,
1686 struct shrink_control *sc)
1688 struct xfs_buftarg *btp = container_of(shrink,
1689 struct xfs_buftarg, bt_shrinker);
1691 unsigned long freed;
1693 freed = list_lru_shrink_walk(&btp->bt_lru, sc,
1694 xfs_buftarg_isolate, &dispose);
1696 while (!list_empty(&dispose)) {
1698 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1699 list_del_init(&bp->b_lru);
1706 static unsigned long
1707 xfs_buftarg_shrink_count(
1708 struct shrinker *shrink,
1709 struct shrink_control *sc)
1711 struct xfs_buftarg *btp = container_of(shrink,
1712 struct xfs_buftarg, bt_shrinker);
1713 return list_lru_shrink_count(&btp->bt_lru, sc);
1718 struct xfs_buftarg *btp)
1720 unregister_shrinker(&btp->bt_shrinker);
1721 ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
1722 percpu_counter_destroy(&btp->bt_io_count);
1723 list_lru_destroy(&btp->bt_lru);
1725 xfs_blkdev_issue_flush(btp);
1731 xfs_setsize_buftarg(
1733 unsigned int sectorsize)
1735 /* Set up metadata sector size info */
1736 btp->bt_meta_sectorsize = sectorsize;
1737 btp->bt_meta_sectormask = sectorsize - 1;
1739 if (set_blocksize(btp->bt_bdev, sectorsize)) {
1740 xfs_warn(btp->bt_mount,
1741 "Cannot set_blocksize to %u on device %pg",
1742 sectorsize, btp->bt_bdev);
1746 /* Set up device logical sector size mask */
1747 btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);
1748 btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;
1754 * When allocating the initial buffer target we have not yet
1755 * read in the superblock, so don't know what sized sectors
1756 * are being used at this early stage. Play safe.
1759 xfs_setsize_buftarg_early(
1761 struct block_device *bdev)
1763 return xfs_setsize_buftarg(btp, bdev_logical_block_size(bdev));
1768 struct xfs_mount *mp,
1769 struct block_device *bdev,
1770 struct dax_device *dax_dev)
1774 btp = kmem_zalloc(sizeof(*btp), KM_NOFS);
1777 btp->bt_dev = bdev->bd_dev;
1778 btp->bt_bdev = bdev;
1779 btp->bt_daxdev = dax_dev;
1781 if (xfs_setsize_buftarg_early(btp, bdev))
1784 if (list_lru_init(&btp->bt_lru))
1787 if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
1790 btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
1791 btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
1792 btp->bt_shrinker.seeks = DEFAULT_SEEKS;
1793 btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
1794 if (register_shrinker(&btp->bt_shrinker))
1799 percpu_counter_destroy(&btp->bt_io_count);
1801 list_lru_destroy(&btp->bt_lru);
1808 * Cancel a delayed write list.
1810 * Remove each buffer from the list, clear the delwri queue flag and drop the
1811 * associated buffer reference.
1814 xfs_buf_delwri_cancel(
1815 struct list_head *list)
1819 while (!list_empty(list)) {
1820 bp = list_first_entry(list, struct xfs_buf, b_list);
1823 bp->b_flags &= ~_XBF_DELWRI_Q;
1824 list_del_init(&bp->b_list);
1830 * Add a buffer to the delayed write list.
1832 * This queues a buffer for writeout if it hasn't already been. Note that
1833 * neither this routine nor the buffer list submission functions perform
1834 * any internal synchronization. It is expected that the lists are thread-local
1837 * Returns true if we queued up the buffer, or false if it already had
1838 * been on the buffer list.
1841 xfs_buf_delwri_queue(
1843 struct list_head *list)
1845 ASSERT(xfs_buf_islocked(bp));
1846 ASSERT(!(bp->b_flags & XBF_READ));
1849 * If the buffer is already marked delwri it already is queued up
1850 * by someone else for imediate writeout. Just ignore it in that
1853 if (bp->b_flags & _XBF_DELWRI_Q) {
1854 trace_xfs_buf_delwri_queued(bp, _RET_IP_);
1858 trace_xfs_buf_delwri_queue(bp, _RET_IP_);
1861 * If a buffer gets written out synchronously or marked stale while it
1862 * is on a delwri list we lazily remove it. To do this, the other party
1863 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1864 * It remains referenced and on the list. In a rare corner case it
1865 * might get readded to a delwri list after the synchronous writeout, in
1866 * which case we need just need to re-add the flag here.
1868 bp->b_flags |= _XBF_DELWRI_Q;
1869 if (list_empty(&bp->b_list)) {
1870 atomic_inc(&bp->b_hold);
1871 list_add_tail(&bp->b_list, list);
1878 * Compare function is more complex than it needs to be because
1879 * the return value is only 32 bits and we are doing comparisons
1885 struct list_head *a,
1886 struct list_head *b)
1888 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
1889 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
1892 diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
1901 * Submit buffers for write. If wait_list is specified, the buffers are
1902 * submitted using sync I/O and placed on the wait list such that the caller can
1903 * iowait each buffer. Otherwise async I/O is used and the buffers are released
1904 * at I/O completion time. In either case, buffers remain locked until I/O
1905 * completes and the buffer is released from the queue.
1908 xfs_buf_delwri_submit_buffers(
1909 struct list_head *buffer_list,
1910 struct list_head *wait_list)
1912 struct xfs_buf *bp, *n;
1914 struct blk_plug plug;
1916 list_sort(NULL, buffer_list, xfs_buf_cmp);
1918 blk_start_plug(&plug);
1919 list_for_each_entry_safe(bp, n, buffer_list, b_list) {
1921 if (xfs_buf_ispinned(bp)) {
1925 if (!xfs_buf_trylock(bp))
1932 * Someone else might have written the buffer synchronously or
1933 * marked it stale in the meantime. In that case only the
1934 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1935 * reference and remove it from the list here.
1937 if (!(bp->b_flags & _XBF_DELWRI_Q)) {
1938 list_del_init(&bp->b_list);
1943 trace_xfs_buf_delwri_split(bp, _RET_IP_);
1946 * If we have a wait list, each buffer (and associated delwri
1947 * queue reference) transfers to it and is submitted
1948 * synchronously. Otherwise, drop the buffer from the delwri
1949 * queue and submit async.
1951 bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_WRITE_FAIL);
1952 bp->b_flags |= XBF_WRITE;
1954 bp->b_flags &= ~XBF_ASYNC;
1955 list_move_tail(&bp->b_list, wait_list);
1957 bp->b_flags |= XBF_ASYNC;
1958 list_del_init(&bp->b_list);
1960 __xfs_buf_submit(bp, false);
1962 blk_finish_plug(&plug);
1968 * Write out a buffer list asynchronously.
1970 * This will take the @buffer_list, write all non-locked and non-pinned buffers
1971 * out and not wait for I/O completion on any of the buffers. This interface
1972 * is only safely useable for callers that can track I/O completion by higher
1973 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
1976 * Note: this function will skip buffers it would block on, and in doing so
1977 * leaves them on @buffer_list so they can be retried on a later pass. As such,
1978 * it is up to the caller to ensure that the buffer list is fully submitted or
1979 * cancelled appropriately when they are finished with the list. Failure to
1980 * cancel or resubmit the list until it is empty will result in leaked buffers
1984 xfs_buf_delwri_submit_nowait(
1985 struct list_head *buffer_list)
1987 return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
1991 * Write out a buffer list synchronously.
1993 * This will take the @buffer_list, write all buffers out and wait for I/O
1994 * completion on all of the buffers. @buffer_list is consumed by the function,
1995 * so callers must have some other way of tracking buffers if they require such
1999 xfs_buf_delwri_submit(
2000 struct list_head *buffer_list)
2002 LIST_HEAD (wait_list);
2003 int error = 0, error2;
2006 xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);
2008 /* Wait for IO to complete. */
2009 while (!list_empty(&wait_list)) {
2010 bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
2012 list_del_init(&bp->b_list);
2015 * Wait on the locked buffer, check for errors and unlock and
2016 * release the delwri queue reference.
2018 error2 = xfs_buf_iowait(bp);
2028 * Push a single buffer on a delwri queue.
2030 * The purpose of this function is to submit a single buffer of a delwri queue
2031 * and return with the buffer still on the original queue. The waiting delwri
2032 * buffer submission infrastructure guarantees transfer of the delwri queue
2033 * buffer reference to a temporary wait list. We reuse this infrastructure to
2034 * transfer the buffer back to the original queue.
2036 * Note the buffer transitions from the queued state, to the submitted and wait
2037 * listed state and back to the queued state during this call. The buffer
2038 * locking and queue management logic between _delwri_pushbuf() and
2039 * _delwri_queue() guarantee that the buffer cannot be queued to another list
2043 xfs_buf_delwri_pushbuf(
2045 struct list_head *buffer_list)
2047 LIST_HEAD (submit_list);
2050 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
2052 trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);
2055 * Isolate the buffer to a new local list so we can submit it for I/O
2056 * independently from the rest of the original list.
2059 list_move(&bp->b_list, &submit_list);
2063 * Delwri submission clears the DELWRI_Q buffer flag and returns with
2064 * the buffer on the wait list with the original reference. Rather than
2065 * bounce the buffer from a local wait list back to the original list
2066 * after I/O completion, reuse the original list as the wait list.
2068 xfs_buf_delwri_submit_buffers(&submit_list, buffer_list);
2071 * The buffer is now locked, under I/O and wait listed on the original
2072 * delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
2073 * return with the buffer unlocked and on the original queue.
2075 error = xfs_buf_iowait(bp);
2076 bp->b_flags |= _XBF_DELWRI_Q;
2085 xfs_buf_zone = kmem_cache_create("xfs_buf",
2086 sizeof(struct xfs_buf), 0,
2087 SLAB_HWCACHE_ALIGN, NULL);
2098 xfs_buf_terminate(void)
2100 kmem_cache_destroy(xfs_buf_zone);
2103 void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
2106 * Set the lru reference count to 0 based on the error injection tag.
2107 * This allows userspace to disrupt buffer caching for debug/testing
2110 if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
2113 atomic_set(&bp->b_lru_ref, lru_ref);
2117 * Verify an on-disk magic value against the magic value specified in the
2118 * verifier structure. The verifier magic is in disk byte order so the caller is
2119 * expected to pass the value directly from disk.
2126 struct xfs_mount *mp = bp->b_mount;
2129 idx = xfs_sb_version_hascrc(&mp->m_sb);
2130 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))
2132 return dmagic == bp->b_ops->magic[idx];
2135 * Verify an on-disk magic value against the magic value specified in the
2136 * verifier structure. The verifier magic is in disk byte order so the caller is
2137 * expected to pass the value directly from disk.
2144 struct xfs_mount *mp = bp->b_mount;
2147 idx = xfs_sb_version_hascrc(&mp->m_sb);
2148 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))
2150 return dmagic == bp->b_ops->magic16[idx];