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 if (current
->reclaim_state
)
331 current
->reclaim_state
->reclaimed_slab
+=
333 } else if (bp
->b_flags
& _XBF_KMEM
)
334 kmem_free(bp
->b_addr
);
335 _xfs_buf_free_pages(bp
);
336 xfs_buf_free_maps(bp
);
337 kmem_cache_free(xfs_buf_zone
, bp
);
341 * Allocates all the pages for buffer in question and builds it's page list.
344 xfs_buf_allocate_memory(
349 size_t nbytes
, offset
;
350 gfp_t gfp_mask
= xb_to_gfp(flags
);
351 unsigned short page_count
, i
;
352 xfs_off_t start
, end
;
354 xfs_km_flags_t kmflag_mask
= 0;
357 * assure zeroed buffer for non-read cases.
359 if (!(flags
& XBF_READ
)) {
360 kmflag_mask
|= KM_ZERO
;
361 gfp_mask
|= __GFP_ZERO
;
365 * for buffers that are contained within a single page, just allocate
366 * the memory from the heap - there's no need for the complexity of
367 * page arrays to keep allocation down to order 0.
369 size
= BBTOB(bp
->b_length
);
370 if (size
< PAGE_SIZE
) {
371 int align_mask
= xfs_buftarg_dma_alignment(bp
->b_target
);
372 bp
->b_addr
= kmem_alloc_io(size
, align_mask
,
373 KM_NOFS
| kmflag_mask
);
375 /* low memory - use alloc_page loop instead */
379 if (((unsigned long)(bp
->b_addr
+ size
- 1) & PAGE_MASK
) !=
380 ((unsigned long)bp
->b_addr
& PAGE_MASK
)) {
381 /* b_addr spans two pages - use alloc_page instead */
382 kmem_free(bp
->b_addr
);
386 bp
->b_offset
= offset_in_page(bp
->b_addr
);
387 bp
->b_pages
= bp
->b_page_array
;
388 bp
->b_pages
[0] = kmem_to_page(bp
->b_addr
);
389 bp
->b_page_count
= 1;
390 bp
->b_flags
|= _XBF_KMEM
;
395 start
= BBTOB(bp
->b_maps
[0].bm_bn
) >> PAGE_SHIFT
;
396 end
= (BBTOB(bp
->b_maps
[0].bm_bn
+ bp
->b_length
) + PAGE_SIZE
- 1)
398 page_count
= end
- start
;
399 error
= _xfs_buf_get_pages(bp
, page_count
);
403 offset
= bp
->b_offset
;
404 bp
->b_flags
|= _XBF_PAGES
;
406 for (i
= 0; i
< bp
->b_page_count
; i
++) {
410 page
= alloc_page(gfp_mask
);
411 if (unlikely(page
== NULL
)) {
412 if (flags
& XBF_READ_AHEAD
) {
413 bp
->b_page_count
= i
;
419 * This could deadlock.
421 * But until all the XFS lowlevel code is revamped to
422 * handle buffer allocation failures we can't do much.
424 if (!(++retries
% 100))
426 "%s(%u) possible memory allocation deadlock in %s (mode:0x%x)",
427 current
->comm
, current
->pid
,
430 XFS_STATS_INC(bp
->b_mount
, xb_page_retries
);
431 congestion_wait(BLK_RW_ASYNC
, HZ
/50);
435 XFS_STATS_INC(bp
->b_mount
, xb_page_found
);
437 nbytes
= min_t(size_t, size
, PAGE_SIZE
- offset
);
439 bp
->b_pages
[i
] = page
;
445 for (i
= 0; i
< bp
->b_page_count
; i
++)
446 __free_page(bp
->b_pages
[i
]);
447 bp
->b_flags
&= ~_XBF_PAGES
;
452 * Map buffer into kernel address-space if necessary.
459 ASSERT(bp
->b_flags
& _XBF_PAGES
);
460 if (bp
->b_page_count
== 1) {
461 /* A single page buffer is always mappable */
462 bp
->b_addr
= page_address(bp
->b_pages
[0]) + bp
->b_offset
;
463 } else if (flags
& XBF_UNMAPPED
) {
470 * vm_map_ram() will allocate auxiliary structures (e.g.
471 * pagetables) with GFP_KERNEL, yet we are likely to be under
472 * GFP_NOFS context here. Hence we need to tell memory reclaim
473 * that we are in such a context via PF_MEMALLOC_NOFS to prevent
474 * memory reclaim re-entering the filesystem here and
475 * potentially deadlocking.
477 nofs_flag
= memalloc_nofs_save();
479 bp
->b_addr
= vm_map_ram(bp
->b_pages
, bp
->b_page_count
,
484 } while (retried
++ <= 1);
485 memalloc_nofs_restore(nofs_flag
);
489 bp
->b_addr
+= bp
->b_offset
;
496 * Finding and Reading Buffers
500 struct rhashtable_compare_arg
*arg
,
503 const struct xfs_buf_map
*map
= arg
->key
;
504 const struct xfs_buf
*bp
= obj
;
507 * The key hashing in the lookup path depends on the key being the
508 * first element of the compare_arg, make sure to assert this.
510 BUILD_BUG_ON(offsetof(struct xfs_buf_map
, bm_bn
) != 0);
512 if (bp
->b_bn
!= map
->bm_bn
)
515 if (unlikely(bp
->b_length
!= map
->bm_len
)) {
517 * found a block number match. If the range doesn't
518 * match, the only way this is allowed is if the buffer
519 * in the cache is stale and the transaction that made
520 * it stale has not yet committed. i.e. we are
521 * reallocating a busy extent. Skip this buffer and
522 * continue searching for an exact match.
524 ASSERT(bp
->b_flags
& XBF_STALE
);
530 static const struct rhashtable_params xfs_buf_hash_params
= {
531 .min_size
= 32, /* empty AGs have minimal footprint */
533 .key_len
= sizeof(xfs_daddr_t
),
534 .key_offset
= offsetof(struct xfs_buf
, b_bn
),
535 .head_offset
= offsetof(struct xfs_buf
, b_rhash_head
),
536 .automatic_shrinking
= true,
537 .obj_cmpfn
= _xfs_buf_obj_cmp
,
542 struct xfs_perag
*pag
)
544 spin_lock_init(&pag
->pag_buf_lock
);
545 return rhashtable_init(&pag
->pag_buf_hash
, &xfs_buf_hash_params
);
549 xfs_buf_hash_destroy(
550 struct xfs_perag
*pag
)
552 rhashtable_destroy(&pag
->pag_buf_hash
);
556 * Look up a buffer in the buffer cache and return it referenced and locked
559 * If @new_bp is supplied and we have a lookup miss, insert @new_bp into the
562 * If XBF_TRYLOCK is set in @flags, only try to lock the buffer and return
563 * -EAGAIN if we fail to lock it.
566 * -EFSCORRUPTED if have been supplied with an invalid address
567 * -EAGAIN on trylock failure
568 * -ENOENT if we fail to find a match and @new_bp was NULL
570 * - @new_bp if we inserted it into the cache
571 * - the buffer we found and locked.
575 struct xfs_buftarg
*btp
,
576 struct xfs_buf_map
*map
,
578 xfs_buf_flags_t flags
,
579 struct xfs_buf
*new_bp
,
580 struct xfs_buf
**found_bp
)
582 struct xfs_perag
*pag
;
584 struct xfs_buf_map cmap
= { .bm_bn
= map
[0].bm_bn
};
590 for (i
= 0; i
< nmaps
; i
++)
591 cmap
.bm_len
+= map
[i
].bm_len
;
593 /* Check for IOs smaller than the sector size / not sector aligned */
594 ASSERT(!(BBTOB(cmap
.bm_len
) < btp
->bt_meta_sectorsize
));
595 ASSERT(!(BBTOB(cmap
.bm_bn
) & (xfs_off_t
)btp
->bt_meta_sectormask
));
598 * Corrupted block numbers can get through to here, unfortunately, so we
599 * have to check that the buffer falls within the filesystem bounds.
601 eofs
= XFS_FSB_TO_BB(btp
->bt_mount
, btp
->bt_mount
->m_sb
.sb_dblocks
);
602 if (cmap
.bm_bn
< 0 || cmap
.bm_bn
>= eofs
) {
603 xfs_alert(btp
->bt_mount
,
604 "%s: daddr 0x%llx out of range, EOFS 0x%llx",
605 __func__
, cmap
.bm_bn
, eofs
);
607 return -EFSCORRUPTED
;
610 pag
= xfs_perag_get(btp
->bt_mount
,
611 xfs_daddr_to_agno(btp
->bt_mount
, cmap
.bm_bn
));
613 spin_lock(&pag
->pag_buf_lock
);
614 bp
= rhashtable_lookup_fast(&pag
->pag_buf_hash
, &cmap
,
615 xfs_buf_hash_params
);
617 atomic_inc(&bp
->b_hold
);
623 XFS_STATS_INC(btp
->bt_mount
, xb_miss_locked
);
624 spin_unlock(&pag
->pag_buf_lock
);
629 /* the buffer keeps the perag reference until it is freed */
631 rhashtable_insert_fast(&pag
->pag_buf_hash
, &new_bp
->b_rhash_head
,
632 xfs_buf_hash_params
);
633 spin_unlock(&pag
->pag_buf_lock
);
638 spin_unlock(&pag
->pag_buf_lock
);
641 if (!xfs_buf_trylock(bp
)) {
642 if (flags
& XBF_TRYLOCK
) {
644 XFS_STATS_INC(btp
->bt_mount
, xb_busy_locked
);
648 XFS_STATS_INC(btp
->bt_mount
, xb_get_locked_waited
);
652 * if the buffer is stale, clear all the external state associated with
653 * it. We need to keep flags such as how we allocated the buffer memory
656 if (bp
->b_flags
& XBF_STALE
) {
657 ASSERT((bp
->b_flags
& _XBF_DELWRI_Q
) == 0);
658 ASSERT(bp
->b_iodone
== NULL
);
659 bp
->b_flags
&= _XBF_KMEM
| _XBF_PAGES
;
663 trace_xfs_buf_find(bp
, flags
, _RET_IP_
);
664 XFS_STATS_INC(btp
->bt_mount
, xb_get_locked
);
671 struct xfs_buftarg
*target
,
674 xfs_buf_flags_t flags
)
678 DEFINE_SINGLE_BUF_MAP(map
, blkno
, numblks
);
680 error
= xfs_buf_find(target
, &map
, 1, flags
, NULL
, &bp
);
687 * Assembles a buffer covering the specified range. The code is optimised for
688 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
689 * more hits than misses.
693 struct xfs_buftarg
*target
,
694 struct xfs_buf_map
*map
,
696 xfs_buf_flags_t flags
,
697 struct xfs_buf
**bpp
)
700 struct xfs_buf
*new_bp
;
704 error
= xfs_buf_find(target
, map
, nmaps
, flags
, NULL
, &bp
);
707 if (error
!= -ENOENT
)
710 error
= _xfs_buf_alloc(target
, map
, nmaps
, flags
, &new_bp
);
714 error
= xfs_buf_allocate_memory(new_bp
, flags
);
716 xfs_buf_free(new_bp
);
720 error
= xfs_buf_find(target
, map
, nmaps
, flags
, new_bp
, &bp
);
722 xfs_buf_free(new_bp
);
727 xfs_buf_free(new_bp
);
731 error
= _xfs_buf_map_pages(bp
, flags
);
732 if (unlikely(error
)) {
733 xfs_warn_ratelimited(target
->bt_mount
,
734 "%s: failed to map %u pages", __func__
,
742 * Clear b_error if this is a lookup from a caller that doesn't expect
743 * valid data to be found in the buffer.
745 if (!(flags
& XBF_READ
))
746 xfs_buf_ioerror(bp
, 0);
748 XFS_STATS_INC(target
->bt_mount
, xb_get
);
749 trace_xfs_buf_get(bp
, flags
, _RET_IP_
);
757 xfs_buf_flags_t flags
)
759 ASSERT(!(flags
& XBF_WRITE
));
760 ASSERT(bp
->b_maps
[0].bm_bn
!= XFS_BUF_DADDR_NULL
);
762 bp
->b_flags
&= ~(XBF_WRITE
| XBF_ASYNC
| XBF_READ_AHEAD
);
763 bp
->b_flags
|= flags
& (XBF_READ
| XBF_ASYNC
| XBF_READ_AHEAD
);
765 return xfs_buf_submit(bp
);
769 * Reverify a buffer found in cache without an attached ->b_ops.
771 * If the caller passed an ops structure and the buffer doesn't have ops
772 * assigned, set the ops and use it to verify the contents. If verification
773 * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
774 * already in XBF_DONE state on entry.
776 * Under normal operations, every in-core buffer is verified on read I/O
777 * completion. There are two scenarios that can lead to in-core buffers without
778 * an assigned ->b_ops. The first is during log recovery of buffers on a V4
779 * filesystem, though these buffers are purged at the end of recovery. The
780 * other is online repair, which intentionally reads with a NULL buffer ops to
781 * run several verifiers across an in-core buffer in order to establish buffer
782 * type. If repair can't establish that, the buffer will be left in memory
783 * with NULL buffer ops.
788 const struct xfs_buf_ops
*ops
)
790 ASSERT(bp
->b_flags
& XBF_DONE
);
791 ASSERT(bp
->b_error
== 0);
793 if (!ops
|| bp
->b_ops
)
797 bp
->b_ops
->verify_read(bp
);
799 bp
->b_flags
&= ~XBF_DONE
;
805 struct xfs_buftarg
*target
,
806 struct xfs_buf_map
*map
,
808 xfs_buf_flags_t flags
,
809 struct xfs_buf
**bpp
,
810 const struct xfs_buf_ops
*ops
,
819 error
= xfs_buf_get_map(target
, map
, nmaps
, flags
, &bp
);
823 trace_xfs_buf_read(bp
, flags
, _RET_IP_
);
825 if (!(bp
->b_flags
& XBF_DONE
)) {
826 /* Initiate the buffer read and wait. */
827 XFS_STATS_INC(target
->bt_mount
, xb_get_read
);
829 error
= _xfs_buf_read(bp
, flags
);
831 /* Readahead iodone already dropped the buffer, so exit. */
832 if (flags
& XBF_ASYNC
)
835 /* Buffer already read; all we need to do is check it. */
836 error
= xfs_buf_reverify(bp
, ops
);
838 /* Readahead already finished; drop the buffer and exit. */
839 if (flags
& XBF_ASYNC
) {
844 /* We do not want read in the flags */
845 bp
->b_flags
&= ~XBF_READ
;
846 ASSERT(bp
->b_ops
!= NULL
|| ops
== NULL
);
850 * If we've had a read error, then the contents of the buffer are
851 * invalid and should not be used. To ensure that a followup read tries
852 * to pull the buffer from disk again, we clear the XBF_DONE flag and
853 * mark the buffer stale. This ensures that anyone who has a current
854 * reference to the buffer will interpret it's contents correctly and
855 * future cache lookups will also treat it as an empty, uninitialised
859 if (!XFS_FORCED_SHUTDOWN(target
->bt_mount
))
860 xfs_buf_ioerror_alert(bp
, fa
);
862 bp
->b_flags
&= ~XBF_DONE
;
866 /* bad CRC means corrupted metadata */
867 if (error
== -EFSBADCRC
)
868 error
= -EFSCORRUPTED
;
877 * If we are not low on memory then do the readahead in a deadlock
881 xfs_buf_readahead_map(
882 struct xfs_buftarg
*target
,
883 struct xfs_buf_map
*map
,
885 const struct xfs_buf_ops
*ops
)
889 if (bdi_read_congested(target
->bt_bdev
->bd_bdi
))
892 xfs_buf_read_map(target
, map
, nmaps
,
893 XBF_TRYLOCK
| XBF_ASYNC
| XBF_READ_AHEAD
, &bp
, ops
,
898 * Read an uncached buffer from disk. Allocates and returns a locked
899 * buffer containing the disk contents or nothing.
902 xfs_buf_read_uncached(
903 struct xfs_buftarg
*target
,
907 struct xfs_buf
**bpp
,
908 const struct xfs_buf_ops
*ops
)
915 error
= xfs_buf_get_uncached(target
, numblks
, flags
, &bp
);
919 /* set up the buffer for a read IO */
920 ASSERT(bp
->b_map_count
== 1);
921 bp
->b_bn
= XFS_BUF_DADDR_NULL
; /* always null for uncached buffers */
922 bp
->b_maps
[0].bm_bn
= daddr
;
923 bp
->b_flags
|= XBF_READ
;
938 xfs_buf_get_uncached(
939 struct xfs_buftarg
*target
,
942 struct xfs_buf
**bpp
)
944 unsigned long page_count
;
947 DEFINE_SINGLE_BUF_MAP(map
, XFS_BUF_DADDR_NULL
, numblks
);
951 /* flags might contain irrelevant bits, pass only what we care about */
952 error
= _xfs_buf_alloc(target
, &map
, 1, flags
& XBF_NO_IOACCT
, &bp
);
956 page_count
= PAGE_ALIGN(numblks
<< BBSHIFT
) >> PAGE_SHIFT
;
957 error
= _xfs_buf_get_pages(bp
, page_count
);
961 for (i
= 0; i
< page_count
; i
++) {
962 bp
->b_pages
[i
] = alloc_page(xb_to_gfp(flags
));
963 if (!bp
->b_pages
[i
]) {
968 bp
->b_flags
|= _XBF_PAGES
;
970 error
= _xfs_buf_map_pages(bp
, 0);
971 if (unlikely(error
)) {
972 xfs_warn(target
->bt_mount
,
973 "%s: failed to map pages", __func__
);
977 trace_xfs_buf_get_uncached(bp
, _RET_IP_
);
983 __free_page(bp
->b_pages
[i
]);
984 _xfs_buf_free_pages(bp
);
986 xfs_buf_free_maps(bp
);
987 kmem_cache_free(xfs_buf_zone
, bp
);
993 * Increment reference count on buffer, to hold the buffer concurrently
994 * with another thread which may release (free) the buffer asynchronously.
995 * Must hold the buffer already to call this function.
1001 trace_xfs_buf_hold(bp
, _RET_IP_
);
1002 atomic_inc(&bp
->b_hold
);
1006 * Release a hold on the specified buffer. If the hold count is 1, the buffer is
1007 * placed on LRU or freed (depending on b_lru_ref).
1013 struct xfs_perag
*pag
= bp
->b_pag
;
1015 bool freebuf
= false;
1017 trace_xfs_buf_rele(bp
, _RET_IP_
);
1020 ASSERT(list_empty(&bp
->b_lru
));
1021 if (atomic_dec_and_test(&bp
->b_hold
)) {
1022 xfs_buf_ioacct_dec(bp
);
1028 ASSERT(atomic_read(&bp
->b_hold
) > 0);
1031 * We grab the b_lock here first to serialise racing xfs_buf_rele()
1032 * calls. The pag_buf_lock being taken on the last reference only
1033 * serialises against racing lookups in xfs_buf_find(). IOWs, the second
1034 * to last reference we drop here is not serialised against the last
1035 * reference until we take bp->b_lock. Hence if we don't grab b_lock
1036 * first, the last "release" reference can win the race to the lock and
1037 * free the buffer before the second-to-last reference is processed,
1038 * leading to a use-after-free scenario.
1040 spin_lock(&bp
->b_lock
);
1041 release
= atomic_dec_and_lock(&bp
->b_hold
, &pag
->pag_buf_lock
);
1044 * Drop the in-flight state if the buffer is already on the LRU
1045 * and it holds the only reference. This is racy because we
1046 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
1047 * ensures the decrement occurs only once per-buf.
1049 if ((atomic_read(&bp
->b_hold
) == 1) && !list_empty(&bp
->b_lru
))
1050 __xfs_buf_ioacct_dec(bp
);
1054 /* the last reference has been dropped ... */
1055 __xfs_buf_ioacct_dec(bp
);
1056 if (!(bp
->b_flags
& XBF_STALE
) && atomic_read(&bp
->b_lru_ref
)) {
1058 * If the buffer is added to the LRU take a new reference to the
1059 * buffer for the LRU and clear the (now stale) dispose list
1062 if (list_lru_add(&bp
->b_target
->bt_lru
, &bp
->b_lru
)) {
1063 bp
->b_state
&= ~XFS_BSTATE_DISPOSE
;
1064 atomic_inc(&bp
->b_hold
);
1066 spin_unlock(&pag
->pag_buf_lock
);
1069 * most of the time buffers will already be removed from the
1070 * LRU, so optimise that case by checking for the
1071 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1072 * was on was the disposal list
1074 if (!(bp
->b_state
& XFS_BSTATE_DISPOSE
)) {
1075 list_lru_del(&bp
->b_target
->bt_lru
, &bp
->b_lru
);
1077 ASSERT(list_empty(&bp
->b_lru
));
1080 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
1081 rhashtable_remove_fast(&pag
->pag_buf_hash
, &bp
->b_rhash_head
,
1082 xfs_buf_hash_params
);
1083 spin_unlock(&pag
->pag_buf_lock
);
1089 spin_unlock(&bp
->b_lock
);
1097 * Lock a buffer object, if it is not already locked.
1099 * If we come across a stale, pinned, locked buffer, we know that we are
1100 * being asked to lock a buffer that has been reallocated. Because it is
1101 * pinned, we know that the log has not been pushed to disk and hence it
1102 * will still be locked. Rather than continuing to have trylock attempts
1103 * fail until someone else pushes the log, push it ourselves before
1104 * returning. This means that the xfsaild will not get stuck trying
1105 * to push on stale inode buffers.
1113 locked
= down_trylock(&bp
->b_sema
) == 0;
1115 trace_xfs_buf_trylock(bp
, _RET_IP_
);
1117 trace_xfs_buf_trylock_fail(bp
, _RET_IP_
);
1122 * Lock a buffer object.
1124 * If we come across a stale, pinned, locked buffer, we know that we
1125 * are being asked to lock a buffer that has been reallocated. Because
1126 * it is pinned, we know that the log has not been pushed to disk and
1127 * hence it will still be locked. Rather than sleeping until someone
1128 * else pushes the log, push it ourselves before trying to get the lock.
1134 trace_xfs_buf_lock(bp
, _RET_IP_
);
1136 if (atomic_read(&bp
->b_pin_count
) && (bp
->b_flags
& XBF_STALE
))
1137 xfs_log_force(bp
->b_mount
, 0);
1140 trace_xfs_buf_lock_done(bp
, _RET_IP_
);
1147 ASSERT(xfs_buf_islocked(bp
));
1150 trace_xfs_buf_unlock(bp
, _RET_IP_
);
1157 DECLARE_WAITQUEUE (wait
, current
);
1159 if (atomic_read(&bp
->b_pin_count
) == 0)
1162 add_wait_queue(&bp
->b_waiters
, &wait
);
1164 set_current_state(TASK_UNINTERRUPTIBLE
);
1165 if (atomic_read(&bp
->b_pin_count
) == 0)
1169 remove_wait_queue(&bp
->b_waiters
, &wait
);
1170 set_current_state(TASK_RUNNING
);
1174 * Buffer Utility Routines
1181 bool read
= bp
->b_flags
& XBF_READ
;
1183 trace_xfs_buf_iodone(bp
, _RET_IP_
);
1185 bp
->b_flags
&= ~(XBF_READ
| XBF_WRITE
| XBF_READ_AHEAD
);
1188 * Pull in IO completion errors now. We are guaranteed to be running
1189 * single threaded, so we don't need the lock to read b_io_error.
1191 if (!bp
->b_error
&& bp
->b_io_error
)
1192 xfs_buf_ioerror(bp
, bp
->b_io_error
);
1194 /* Only validate buffers that were read without errors */
1195 if (read
&& !bp
->b_error
&& bp
->b_ops
) {
1196 ASSERT(!bp
->b_iodone
);
1197 bp
->b_ops
->verify_read(bp
);
1201 bp
->b_flags
|= XBF_DONE
;
1204 (*(bp
->b_iodone
))(bp
);
1205 else if (bp
->b_flags
& XBF_ASYNC
)
1208 complete(&bp
->b_iowait
);
1213 struct work_struct
*work
)
1215 struct xfs_buf
*bp
=
1216 container_of(work
, xfs_buf_t
, b_ioend_work
);
1222 xfs_buf_ioend_async(
1225 INIT_WORK(&bp
->b_ioend_work
, xfs_buf_ioend_work
);
1226 queue_work(bp
->b_mount
->m_buf_workqueue
, &bp
->b_ioend_work
);
1233 xfs_failaddr_t failaddr
)
1235 ASSERT(error
<= 0 && error
>= -1000);
1236 bp
->b_error
= error
;
1237 trace_xfs_buf_ioerror(bp
, error
, failaddr
);
1241 xfs_buf_ioerror_alert(
1243 xfs_failaddr_t func
)
1245 xfs_alert_ratelimited(bp
->b_mount
,
1246 "metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
1247 func
, (uint64_t)XFS_BUF_ADDR(bp
), bp
->b_length
,
1257 ASSERT(xfs_buf_islocked(bp
));
1259 bp
->b_flags
|= XBF_WRITE
;
1260 bp
->b_flags
&= ~(XBF_ASYNC
| XBF_READ
| _XBF_DELWRI_Q
|
1261 XBF_WRITE_FAIL
| XBF_DONE
);
1263 error
= xfs_buf_submit(bp
);
1265 xfs_force_shutdown(bp
->b_mount
, SHUTDOWN_META_IO_ERROR
);
1273 struct xfs_buf
*bp
= (struct xfs_buf
*)bio
->bi_private
;
1276 * don't overwrite existing errors - otherwise we can lose errors on
1277 * buffers that require multiple bios to complete.
1279 if (bio
->bi_status
) {
1280 int error
= blk_status_to_errno(bio
->bi_status
);
1282 cmpxchg(&bp
->b_io_error
, 0, error
);
1285 if (!bp
->b_error
&& xfs_buf_is_vmapped(bp
) && (bp
->b_flags
& XBF_READ
))
1286 invalidate_kernel_vmap_range(bp
->b_addr
, xfs_buf_vmap_len(bp
));
1288 if (atomic_dec_and_test(&bp
->b_io_remaining
) == 1)
1289 xfs_buf_ioend_async(bp
);
1294 xfs_buf_ioapply_map(
1302 int total_nr_pages
= bp
->b_page_count
;
1305 sector_t sector
= bp
->b_maps
[map
].bm_bn
;
1309 /* skip the pages in the buffer before the start offset */
1311 offset
= *buf_offset
;
1312 while (offset
>= PAGE_SIZE
) {
1314 offset
-= PAGE_SIZE
;
1318 * Limit the IO size to the length of the current vector, and update the
1319 * remaining IO count for the next time around.
1321 size
= min_t(int, BBTOB(bp
->b_maps
[map
].bm_len
), *count
);
1323 *buf_offset
+= size
;
1326 atomic_inc(&bp
->b_io_remaining
);
1327 nr_pages
= min(total_nr_pages
, BIO_MAX_PAGES
);
1329 bio
= bio_alloc(GFP_NOIO
, nr_pages
);
1330 bio_set_dev(bio
, bp
->b_target
->bt_bdev
);
1331 bio
->bi_iter
.bi_sector
= sector
;
1332 bio
->bi_end_io
= xfs_buf_bio_end_io
;
1333 bio
->bi_private
= bp
;
1336 for (; size
&& nr_pages
; nr_pages
--, page_index
++) {
1337 int rbytes
, nbytes
= PAGE_SIZE
- offset
;
1342 rbytes
= bio_add_page(bio
, bp
->b_pages
[page_index
], nbytes
,
1344 if (rbytes
< nbytes
)
1348 sector
+= BTOBB(nbytes
);
1353 if (likely(bio
->bi_iter
.bi_size
)) {
1354 if (xfs_buf_is_vmapped(bp
)) {
1355 flush_kernel_vmap_range(bp
->b_addr
,
1356 xfs_buf_vmap_len(bp
));
1363 * This is guaranteed not to be the last io reference count
1364 * because the caller (xfs_buf_submit) holds a count itself.
1366 atomic_dec(&bp
->b_io_remaining
);
1367 xfs_buf_ioerror(bp
, -EIO
);
1377 struct blk_plug plug
;
1384 * Make sure we capture only current IO errors rather than stale errors
1385 * left over from previous use of the buffer (e.g. failed readahead).
1389 if (bp
->b_flags
& XBF_WRITE
) {
1393 * Run the write verifier callback function if it exists. If
1394 * this function fails it will mark the buffer with an error and
1395 * the IO should not be dispatched.
1398 bp
->b_ops
->verify_write(bp
);
1400 xfs_force_shutdown(bp
->b_mount
,
1401 SHUTDOWN_CORRUPT_INCORE
);
1404 } else if (bp
->b_bn
!= XFS_BUF_DADDR_NULL
) {
1405 struct xfs_mount
*mp
= bp
->b_mount
;
1408 * non-crc filesystems don't attach verifiers during
1409 * log recovery, so don't warn for such filesystems.
1411 if (xfs_sb_version_hascrc(&mp
->m_sb
)) {
1413 "%s: no buf ops on daddr 0x%llx len %d",
1414 __func__
, bp
->b_bn
, bp
->b_length
);
1415 xfs_hex_dump(bp
->b_addr
,
1416 XFS_CORRUPTION_DUMP_LEN
);
1422 if (bp
->b_flags
& XBF_READ_AHEAD
)
1426 /* we only use the buffer cache for meta-data */
1430 * Walk all the vectors issuing IO on them. Set up the initial offset
1431 * into the buffer and the desired IO size before we start -
1432 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1435 offset
= bp
->b_offset
;
1436 size
= BBTOB(bp
->b_length
);
1437 blk_start_plug(&plug
);
1438 for (i
= 0; i
< bp
->b_map_count
; i
++) {
1439 xfs_buf_ioapply_map(bp
, i
, &offset
, &size
, op
);
1443 break; /* all done */
1445 blk_finish_plug(&plug
);
1449 * Wait for I/O completion of a sync buffer and return the I/O error code.
1455 ASSERT(!(bp
->b_flags
& XBF_ASYNC
));
1457 trace_xfs_buf_iowait(bp
, _RET_IP_
);
1458 wait_for_completion(&bp
->b_iowait
);
1459 trace_xfs_buf_iowait_done(bp
, _RET_IP_
);
1465 * Buffer I/O submission path, read or write. Asynchronous submission transfers
1466 * the buffer lock ownership and the current reference to the IO. It is not
1467 * safe to reference the buffer after a call to this function unless the caller
1468 * holds an additional reference itself.
1477 trace_xfs_buf_submit(bp
, _RET_IP_
);
1479 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
1481 /* on shutdown we stale and complete the buffer immediately */
1482 if (XFS_FORCED_SHUTDOWN(bp
->b_mount
)) {
1483 xfs_buf_ioerror(bp
, -EIO
);
1484 bp
->b_flags
&= ~XBF_DONE
;
1491 * Grab a reference so the buffer does not go away underneath us. For
1492 * async buffers, I/O completion drops the callers reference, which
1493 * could occur before submission returns.
1497 if (bp
->b_flags
& XBF_WRITE
)
1498 xfs_buf_wait_unpin(bp
);
1500 /* clear the internal error state to avoid spurious errors */
1504 * Set the count to 1 initially, this will stop an I/O completion
1505 * callout which happens before we have started all the I/O from calling
1506 * xfs_buf_ioend too early.
1508 atomic_set(&bp
->b_io_remaining
, 1);
1509 if (bp
->b_flags
& XBF_ASYNC
)
1510 xfs_buf_ioacct_inc(bp
);
1511 _xfs_buf_ioapply(bp
);
1514 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1515 * reference we took above. If we drop it to zero, run completion so
1516 * that we don't return to the caller with completion still pending.
1518 if (atomic_dec_and_test(&bp
->b_io_remaining
) == 1) {
1519 if (bp
->b_error
|| !(bp
->b_flags
& XBF_ASYNC
))
1522 xfs_buf_ioend_async(bp
);
1526 error
= xfs_buf_iowait(bp
);
1529 * Release the hold that keeps the buffer referenced for the entire
1530 * I/O. Note that if the buffer is async, it is not safe to reference
1531 * after this release.
1545 return bp
->b_addr
+ offset
;
1547 offset
+= bp
->b_offset
;
1548 page
= bp
->b_pages
[offset
>> PAGE_SHIFT
];
1549 return page_address(page
) + (offset
& (PAGE_SIZE
-1));
1560 bend
= boff
+ bsize
;
1561 while (boff
< bend
) {
1563 int page_index
, page_offset
, csize
;
1565 page_index
= (boff
+ bp
->b_offset
) >> PAGE_SHIFT
;
1566 page_offset
= (boff
+ bp
->b_offset
) & ~PAGE_MASK
;
1567 page
= bp
->b_pages
[page_index
];
1568 csize
= min_t(size_t, PAGE_SIZE
- page_offset
,
1569 BBTOB(bp
->b_length
) - boff
);
1571 ASSERT((csize
+ page_offset
) <= PAGE_SIZE
);
1573 memset(page_address(page
) + page_offset
, 0, csize
);
1580 * Log a message about and stale a buffer that a caller has decided is corrupt.
1582 * This function should be called for the kinds of metadata corruption that
1583 * cannot be detect from a verifier, such as incorrect inter-block relationship
1584 * data. Do /not/ call this function from a verifier function.
1586 * The buffer must be XBF_DONE prior to the call. Afterwards, the buffer will
1587 * be marked stale, but b_error will not be set. The caller is responsible for
1588 * releasing the buffer or fixing it.
1591 __xfs_buf_mark_corrupt(
1595 ASSERT(bp
->b_flags
& XBF_DONE
);
1597 xfs_buf_corruption_error(bp
, fa
);
1602 * Handling of buffer targets (buftargs).
1606 * Wait for any bufs with callbacks that have been submitted but have not yet
1607 * returned. These buffers will have an elevated hold count, so wait on those
1608 * while freeing all the buffers only held by the LRU.
1610 static enum lru_status
1611 xfs_buftarg_wait_rele(
1612 struct list_head
*item
,
1613 struct list_lru_one
*lru
,
1614 spinlock_t
*lru_lock
,
1618 struct xfs_buf
*bp
= container_of(item
, struct xfs_buf
, b_lru
);
1619 struct list_head
*dispose
= arg
;
1621 if (atomic_read(&bp
->b_hold
) > 1) {
1622 /* need to wait, so skip it this pass */
1623 trace_xfs_buf_wait_buftarg(bp
, _RET_IP_
);
1626 if (!spin_trylock(&bp
->b_lock
))
1630 * clear the LRU reference count so the buffer doesn't get
1631 * ignored in xfs_buf_rele().
1633 atomic_set(&bp
->b_lru_ref
, 0);
1634 bp
->b_state
|= XFS_BSTATE_DISPOSE
;
1635 list_lru_isolate_move(lru
, item
, dispose
);
1636 spin_unlock(&bp
->b_lock
);
1642 struct xfs_buftarg
*btp
)
1648 * First wait on the buftarg I/O count for all in-flight buffers to be
1649 * released. This is critical as new buffers do not make the LRU until
1650 * they are released.
1652 * Next, flush the buffer workqueue to ensure all completion processing
1653 * has finished. Just waiting on buffer locks is not sufficient for
1654 * async IO as the reference count held over IO is not released until
1655 * after the buffer lock is dropped. Hence we need to ensure here that
1656 * all reference counts have been dropped before we start walking the
1659 while (percpu_counter_sum(&btp
->bt_io_count
))
1661 flush_workqueue(btp
->bt_mount
->m_buf_workqueue
);
1663 /* loop until there is nothing left on the lru list. */
1664 while (list_lru_count(&btp
->bt_lru
)) {
1665 list_lru_walk(&btp
->bt_lru
, xfs_buftarg_wait_rele
,
1666 &dispose
, LONG_MAX
);
1668 while (!list_empty(&dispose
)) {
1670 bp
= list_first_entry(&dispose
, struct xfs_buf
, b_lru
);
1671 list_del_init(&bp
->b_lru
);
1672 if (bp
->b_flags
& XBF_WRITE_FAIL
) {
1673 xfs_alert(btp
->bt_mount
,
1674 "Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
1675 (long long)bp
->b_bn
);
1676 xfs_alert(btp
->bt_mount
,
1677 "Please run xfs_repair to determine the extent of the problem.");
1686 static enum lru_status
1687 xfs_buftarg_isolate(
1688 struct list_head
*item
,
1689 struct list_lru_one
*lru
,
1690 spinlock_t
*lru_lock
,
1693 struct xfs_buf
*bp
= container_of(item
, struct xfs_buf
, b_lru
);
1694 struct list_head
*dispose
= arg
;
1697 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1698 * If we fail to get the lock, just skip it.
1700 if (!spin_trylock(&bp
->b_lock
))
1703 * Decrement the b_lru_ref count unless the value is already
1704 * zero. If the value is already zero, we need to reclaim the
1705 * buffer, otherwise it gets another trip through the LRU.
1707 if (atomic_add_unless(&bp
->b_lru_ref
, -1, 0)) {
1708 spin_unlock(&bp
->b_lock
);
1712 bp
->b_state
|= XFS_BSTATE_DISPOSE
;
1713 list_lru_isolate_move(lru
, item
, dispose
);
1714 spin_unlock(&bp
->b_lock
);
1718 static unsigned long
1719 xfs_buftarg_shrink_scan(
1720 struct shrinker
*shrink
,
1721 struct shrink_control
*sc
)
1723 struct xfs_buftarg
*btp
= container_of(shrink
,
1724 struct xfs_buftarg
, bt_shrinker
);
1726 unsigned long freed
;
1728 freed
= list_lru_shrink_walk(&btp
->bt_lru
, sc
,
1729 xfs_buftarg_isolate
, &dispose
);
1731 while (!list_empty(&dispose
)) {
1733 bp
= list_first_entry(&dispose
, struct xfs_buf
, b_lru
);
1734 list_del_init(&bp
->b_lru
);
1741 static unsigned long
1742 xfs_buftarg_shrink_count(
1743 struct shrinker
*shrink
,
1744 struct shrink_control
*sc
)
1746 struct xfs_buftarg
*btp
= container_of(shrink
,
1747 struct xfs_buftarg
, bt_shrinker
);
1748 return list_lru_shrink_count(&btp
->bt_lru
, sc
);
1753 struct xfs_buftarg
*btp
)
1755 unregister_shrinker(&btp
->bt_shrinker
);
1756 ASSERT(percpu_counter_sum(&btp
->bt_io_count
) == 0);
1757 percpu_counter_destroy(&btp
->bt_io_count
);
1758 list_lru_destroy(&btp
->bt_lru
);
1760 xfs_blkdev_issue_flush(btp
);
1766 xfs_setsize_buftarg(
1768 unsigned int sectorsize
)
1770 /* Set up metadata sector size info */
1771 btp
->bt_meta_sectorsize
= sectorsize
;
1772 btp
->bt_meta_sectormask
= sectorsize
- 1;
1774 if (set_blocksize(btp
->bt_bdev
, sectorsize
)) {
1775 xfs_warn(btp
->bt_mount
,
1776 "Cannot set_blocksize to %u on device %pg",
1777 sectorsize
, btp
->bt_bdev
);
1781 /* Set up device logical sector size mask */
1782 btp
->bt_logical_sectorsize
= bdev_logical_block_size(btp
->bt_bdev
);
1783 btp
->bt_logical_sectormask
= bdev_logical_block_size(btp
->bt_bdev
) - 1;
1789 * When allocating the initial buffer target we have not yet
1790 * read in the superblock, so don't know what sized sectors
1791 * are being used at this early stage. Play safe.
1794 xfs_setsize_buftarg_early(
1796 struct block_device
*bdev
)
1798 return xfs_setsize_buftarg(btp
, bdev_logical_block_size(bdev
));
1803 struct xfs_mount
*mp
,
1804 struct block_device
*bdev
,
1805 struct dax_device
*dax_dev
)
1809 btp
= kmem_zalloc(sizeof(*btp
), KM_NOFS
);
1812 btp
->bt_dev
= bdev
->bd_dev
;
1813 btp
->bt_bdev
= bdev
;
1814 btp
->bt_daxdev
= dax_dev
;
1816 if (xfs_setsize_buftarg_early(btp
, bdev
))
1819 if (list_lru_init(&btp
->bt_lru
))
1822 if (percpu_counter_init(&btp
->bt_io_count
, 0, GFP_KERNEL
))
1825 btp
->bt_shrinker
.count_objects
= xfs_buftarg_shrink_count
;
1826 btp
->bt_shrinker
.scan_objects
= xfs_buftarg_shrink_scan
;
1827 btp
->bt_shrinker
.seeks
= DEFAULT_SEEKS
;
1828 btp
->bt_shrinker
.flags
= SHRINKER_NUMA_AWARE
;
1829 if (register_shrinker(&btp
->bt_shrinker
))
1834 percpu_counter_destroy(&btp
->bt_io_count
);
1836 list_lru_destroy(&btp
->bt_lru
);
1843 * Cancel a delayed write list.
1845 * Remove each buffer from the list, clear the delwri queue flag and drop the
1846 * associated buffer reference.
1849 xfs_buf_delwri_cancel(
1850 struct list_head
*list
)
1854 while (!list_empty(list
)) {
1855 bp
= list_first_entry(list
, struct xfs_buf
, b_list
);
1858 bp
->b_flags
&= ~_XBF_DELWRI_Q
;
1859 list_del_init(&bp
->b_list
);
1865 * Add a buffer to the delayed write list.
1867 * This queues a buffer for writeout if it hasn't already been. Note that
1868 * neither this routine nor the buffer list submission functions perform
1869 * any internal synchronization. It is expected that the lists are thread-local
1872 * Returns true if we queued up the buffer, or false if it already had
1873 * been on the buffer list.
1876 xfs_buf_delwri_queue(
1878 struct list_head
*list
)
1880 ASSERT(xfs_buf_islocked(bp
));
1881 ASSERT(!(bp
->b_flags
& XBF_READ
));
1884 * If the buffer is already marked delwri it already is queued up
1885 * by someone else for imediate writeout. Just ignore it in that
1888 if (bp
->b_flags
& _XBF_DELWRI_Q
) {
1889 trace_xfs_buf_delwri_queued(bp
, _RET_IP_
);
1893 trace_xfs_buf_delwri_queue(bp
, _RET_IP_
);
1896 * If a buffer gets written out synchronously or marked stale while it
1897 * is on a delwri list we lazily remove it. To do this, the other party
1898 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1899 * It remains referenced and on the list. In a rare corner case it
1900 * might get readded to a delwri list after the synchronous writeout, in
1901 * which case we need just need to re-add the flag here.
1903 bp
->b_flags
|= _XBF_DELWRI_Q
;
1904 if (list_empty(&bp
->b_list
)) {
1905 atomic_inc(&bp
->b_hold
);
1906 list_add_tail(&bp
->b_list
, list
);
1913 * Compare function is more complex than it needs to be because
1914 * the return value is only 32 bits and we are doing comparisons
1920 struct list_head
*a
,
1921 struct list_head
*b
)
1923 struct xfs_buf
*ap
= container_of(a
, struct xfs_buf
, b_list
);
1924 struct xfs_buf
*bp
= container_of(b
, struct xfs_buf
, b_list
);
1927 diff
= ap
->b_maps
[0].bm_bn
- bp
->b_maps
[0].bm_bn
;
1936 * Submit buffers for write. If wait_list is specified, the buffers are
1937 * submitted using sync I/O and placed on the wait list such that the caller can
1938 * iowait each buffer. Otherwise async I/O is used and the buffers are released
1939 * at I/O completion time. In either case, buffers remain locked until I/O
1940 * completes and the buffer is released from the queue.
1943 xfs_buf_delwri_submit_buffers(
1944 struct list_head
*buffer_list
,
1945 struct list_head
*wait_list
)
1947 struct xfs_buf
*bp
, *n
;
1949 struct blk_plug plug
;
1951 list_sort(NULL
, buffer_list
, xfs_buf_cmp
);
1953 blk_start_plug(&plug
);
1954 list_for_each_entry_safe(bp
, n
, buffer_list
, b_list
) {
1956 if (xfs_buf_ispinned(bp
)) {
1960 if (!xfs_buf_trylock(bp
))
1967 * Someone else might have written the buffer synchronously or
1968 * marked it stale in the meantime. In that case only the
1969 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1970 * reference and remove it from the list here.
1972 if (!(bp
->b_flags
& _XBF_DELWRI_Q
)) {
1973 list_del_init(&bp
->b_list
);
1978 trace_xfs_buf_delwri_split(bp
, _RET_IP_
);
1981 * If we have a wait list, each buffer (and associated delwri
1982 * queue reference) transfers to it and is submitted
1983 * synchronously. Otherwise, drop the buffer from the delwri
1984 * queue and submit async.
1986 bp
->b_flags
&= ~(_XBF_DELWRI_Q
| XBF_WRITE_FAIL
);
1987 bp
->b_flags
|= XBF_WRITE
;
1989 bp
->b_flags
&= ~XBF_ASYNC
;
1990 list_move_tail(&bp
->b_list
, wait_list
);
1992 bp
->b_flags
|= XBF_ASYNC
;
1993 list_del_init(&bp
->b_list
);
1995 __xfs_buf_submit(bp
, false);
1997 blk_finish_plug(&plug
);
2003 * Write out a buffer list asynchronously.
2005 * This will take the @buffer_list, write all non-locked and non-pinned buffers
2006 * out and not wait for I/O completion on any of the buffers. This interface
2007 * is only safely useable for callers that can track I/O completion by higher
2008 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
2011 * Note: this function will skip buffers it would block on, and in doing so
2012 * leaves them on @buffer_list so they can be retried on a later pass. As such,
2013 * it is up to the caller to ensure that the buffer list is fully submitted or
2014 * cancelled appropriately when they are finished with the list. Failure to
2015 * cancel or resubmit the list until it is empty will result in leaked buffers
2019 xfs_buf_delwri_submit_nowait(
2020 struct list_head
*buffer_list
)
2022 return xfs_buf_delwri_submit_buffers(buffer_list
, NULL
);
2026 * Write out a buffer list synchronously.
2028 * This will take the @buffer_list, write all buffers out and wait for I/O
2029 * completion on all of the buffers. @buffer_list is consumed by the function,
2030 * so callers must have some other way of tracking buffers if they require such
2034 xfs_buf_delwri_submit(
2035 struct list_head
*buffer_list
)
2037 LIST_HEAD (wait_list
);
2038 int error
= 0, error2
;
2041 xfs_buf_delwri_submit_buffers(buffer_list
, &wait_list
);
2043 /* Wait for IO to complete. */
2044 while (!list_empty(&wait_list
)) {
2045 bp
= list_first_entry(&wait_list
, struct xfs_buf
, b_list
);
2047 list_del_init(&bp
->b_list
);
2050 * Wait on the locked buffer, check for errors and unlock and
2051 * release the delwri queue reference.
2053 error2
= xfs_buf_iowait(bp
);
2063 * Push a single buffer on a delwri queue.
2065 * The purpose of this function is to submit a single buffer of a delwri queue
2066 * and return with the buffer still on the original queue. The waiting delwri
2067 * buffer submission infrastructure guarantees transfer of the delwri queue
2068 * buffer reference to a temporary wait list. We reuse this infrastructure to
2069 * transfer the buffer back to the original queue.
2071 * Note the buffer transitions from the queued state, to the submitted and wait
2072 * listed state and back to the queued state during this call. The buffer
2073 * locking and queue management logic between _delwri_pushbuf() and
2074 * _delwri_queue() guarantee that the buffer cannot be queued to another list
2078 xfs_buf_delwri_pushbuf(
2080 struct list_head
*buffer_list
)
2082 LIST_HEAD (submit_list
);
2085 ASSERT(bp
->b_flags
& _XBF_DELWRI_Q
);
2087 trace_xfs_buf_delwri_pushbuf(bp
, _RET_IP_
);
2090 * Isolate the buffer to a new local list so we can submit it for I/O
2091 * independently from the rest of the original list.
2094 list_move(&bp
->b_list
, &submit_list
);
2098 * Delwri submission clears the DELWRI_Q buffer flag and returns with
2099 * the buffer on the wait list with the original reference. Rather than
2100 * bounce the buffer from a local wait list back to the original list
2101 * after I/O completion, reuse the original list as the wait list.
2103 xfs_buf_delwri_submit_buffers(&submit_list
, buffer_list
);
2106 * The buffer is now locked, under I/O and wait listed on the original
2107 * delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
2108 * return with the buffer unlocked and on the original queue.
2110 error
= xfs_buf_iowait(bp
);
2111 bp
->b_flags
|= _XBF_DELWRI_Q
;
2120 xfs_buf_zone
= kmem_cache_create("xfs_buf", sizeof(struct xfs_buf
), 0,
2121 SLAB_HWCACHE_ALIGN
|
2122 SLAB_RECLAIM_ACCOUNT
|
2135 xfs_buf_terminate(void)
2137 kmem_cache_destroy(xfs_buf_zone
);
2140 void xfs_buf_set_ref(struct xfs_buf
*bp
, int lru_ref
)
2143 * Set the lru reference count to 0 based on the error injection tag.
2144 * This allows userspace to disrupt buffer caching for debug/testing
2147 if (XFS_TEST_ERROR(false, bp
->b_mount
, XFS_ERRTAG_BUF_LRU_REF
))
2150 atomic_set(&bp
->b_lru_ref
, lru_ref
);
2154 * Verify an on-disk magic value against the magic value specified in the
2155 * verifier structure. The verifier magic is in disk byte order so the caller is
2156 * expected to pass the value directly from disk.
2163 struct xfs_mount
*mp
= bp
->b_mount
;
2166 idx
= xfs_sb_version_hascrc(&mp
->m_sb
);
2167 if (WARN_ON(!bp
->b_ops
|| !bp
->b_ops
->magic
[idx
]))
2169 return dmagic
== bp
->b_ops
->magic
[idx
];
2172 * Verify an on-disk magic value against the magic value specified in the
2173 * verifier structure. The verifier magic is in disk byte order so the caller is
2174 * expected to pass the value directly from disk.
2181 struct xfs_mount
*mp
= bp
->b_mount
;
2184 idx
= xfs_sb_version_hascrc(&mp
->m_sb
);
2185 if (WARN_ON(!bp
->b_ops
|| !bp
->b_ops
->magic16
[idx
]))
2187 return dmagic
== bp
->b_ops
->magic16
[idx
];