2 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 #include <linux/stddef.h>
20 #include <linux/errno.h>
21 #include <linux/gfp.h>
22 #include <linux/pagemap.h>
23 #include <linux/init.h>
24 #include <linux/vmalloc.h>
25 #include <linux/bio.h>
26 #include <linux/sysctl.h>
27 #include <linux/proc_fs.h>
28 #include <linux/workqueue.h>
29 #include <linux/percpu.h>
30 #include <linux/blkdev.h>
31 #include <linux/hash.h>
32 #include <linux/kthread.h>
33 #include <linux/migrate.h>
34 #include <linux/backing-dev.h>
35 #include <linux/freezer.h>
36 #include <linux/sched/mm.h>
38 #include "xfs_format.h"
39 #include "xfs_log_format.h"
40 #include "xfs_trans_resv.h"
42 #include "xfs_mount.h"
43 #include "xfs_trace.h"
46 static kmem_zone_t
*xfs_buf_zone
;
48 #ifdef XFS_BUF_LOCK_TRACKING
49 # define XB_SET_OWNER(bp) ((bp)->b_last_holder = current->pid)
50 # define XB_CLEAR_OWNER(bp) ((bp)->b_last_holder = -1)
51 # define XB_GET_OWNER(bp) ((bp)->b_last_holder)
53 # define XB_SET_OWNER(bp) do { } while (0)
54 # define XB_CLEAR_OWNER(bp) do { } while (0)
55 # define XB_GET_OWNER(bp) do { } while (0)
58 #define xb_to_gfp(flags) \
59 ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : GFP_NOFS) | __GFP_NOWARN)
67 * Return true if the buffer is vmapped.
69 * b_addr is null if the buffer is not mapped, but the code is clever
70 * enough to know it doesn't have to map a single page, so the check has
71 * to be both for b_addr and bp->b_page_count > 1.
73 return bp
->b_addr
&& bp
->b_page_count
> 1;
80 return (bp
->b_page_count
* PAGE_SIZE
) - bp
->b_offset
;
84 * Bump the I/O in flight count on the buftarg if we haven't yet done so for
85 * this buffer. The count is incremented once per buffer (per hold cycle)
86 * because the corresponding decrement is deferred to buffer release. Buffers
87 * can undergo I/O multiple times in a hold-release cycle and per buffer I/O
88 * tracking adds unnecessary overhead. This is used for sychronization purposes
89 * with unmount (see xfs_wait_buftarg()), so all we really need is a count of
92 * Buffers that are never released (e.g., superblock, iclog buffers) must set
93 * the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count
94 * never reaches zero and unmount hangs indefinitely.
100 if (bp
->b_flags
& (XBF_NO_IOACCT
|_XBF_IN_FLIGHT
))
103 ASSERT(bp
->b_flags
& XBF_ASYNC
);
104 bp
->b_flags
|= _XBF_IN_FLIGHT
;
105 percpu_counter_inc(&bp
->b_target
->bt_io_count
);
109 * Clear the in-flight state on a buffer about to be released to the LRU or
110 * freed and unaccount from the buftarg.
116 if (!(bp
->b_flags
& _XBF_IN_FLIGHT
))
119 bp
->b_flags
&= ~_XBF_IN_FLIGHT
;
120 percpu_counter_dec(&bp
->b_target
->bt_io_count
);
124 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
125 * b_lru_ref count so that the buffer is freed immediately when the buffer
126 * reference count falls to zero. If the buffer is already on the LRU, we need
127 * to remove the reference that LRU holds on the buffer.
129 * This prevents build-up of stale buffers on the LRU.
135 ASSERT(xfs_buf_islocked(bp
));
137 bp
->b_flags
|= XBF_STALE
;
140 * Clear the delwri status so that a delwri queue walker will not
141 * flush this buffer to disk now that it is stale. The delwri queue has
142 * a reference to the buffer, so this is safe to do.
144 bp
->b_flags
&= ~_XBF_DELWRI_Q
;
147 * Once the buffer is marked stale and unlocked, a subsequent lookup
148 * could reset b_flags. There is no guarantee that the buffer is
149 * unaccounted (released to LRU) before that occurs. Drop in-flight
150 * status now to preserve accounting consistency.
152 xfs_buf_ioacct_dec(bp
);
154 spin_lock(&bp
->b_lock
);
155 atomic_set(&bp
->b_lru_ref
, 0);
156 if (!(bp
->b_state
& XFS_BSTATE_DISPOSE
) &&
157 (list_lru_del(&bp
->b_target
->bt_lru
, &bp
->b_lru
)))
158 atomic_dec(&bp
->b_hold
);
160 ASSERT(atomic_read(&bp
->b_hold
) >= 1);
161 spin_unlock(&bp
->b_lock
);
169 ASSERT(bp
->b_maps
== NULL
);
170 bp
->b_map_count
= map_count
;
172 if (map_count
== 1) {
173 bp
->b_maps
= &bp
->__b_map
;
177 bp
->b_maps
= kmem_zalloc(map_count
* sizeof(struct xfs_buf_map
),
185 * Frees b_pages if it was allocated.
191 if (bp
->b_maps
!= &bp
->__b_map
) {
192 kmem_free(bp
->b_maps
);
199 struct xfs_buftarg
*target
,
200 struct xfs_buf_map
*map
,
202 xfs_buf_flags_t flags
)
208 bp
= kmem_zone_zalloc(xfs_buf_zone
, KM_NOFS
);
213 * We don't want certain flags to appear in b_flags unless they are
214 * specifically set by later operations on the buffer.
216 flags
&= ~(XBF_UNMAPPED
| XBF_TRYLOCK
| XBF_ASYNC
| XBF_READ_AHEAD
);
218 atomic_set(&bp
->b_hold
, 1);
219 atomic_set(&bp
->b_lru_ref
, 1);
220 init_completion(&bp
->b_iowait
);
221 INIT_LIST_HEAD(&bp
->b_lru
);
222 INIT_LIST_HEAD(&bp
->b_list
);
223 sema_init(&bp
->b_sema
, 0); /* held, no waiters */
224 spin_lock_init(&bp
->b_lock
);
226 bp
->b_target
= target
;
230 * Set length and io_length to the same value initially.
231 * I/O routines should use io_length, which will be the same in
232 * most cases but may be reset (e.g. XFS recovery).
234 error
= xfs_buf_get_maps(bp
, nmaps
);
236 kmem_zone_free(xfs_buf_zone
, bp
);
240 bp
->b_bn
= map
[0].bm_bn
;
242 for (i
= 0; i
< nmaps
; i
++) {
243 bp
->b_maps
[i
].bm_bn
= map
[i
].bm_bn
;
244 bp
->b_maps
[i
].bm_len
= map
[i
].bm_len
;
245 bp
->b_length
+= map
[i
].bm_len
;
247 bp
->b_io_length
= bp
->b_length
;
249 atomic_set(&bp
->b_pin_count
, 0);
250 init_waitqueue_head(&bp
->b_waiters
);
252 XFS_STATS_INC(target
->bt_mount
, xb_create
);
253 trace_xfs_buf_init(bp
, _RET_IP_
);
259 * Allocate a page array capable of holding a specified number
260 * of pages, and point the page buf at it.
267 /* Make sure that we have a page list */
268 if (bp
->b_pages
== NULL
) {
269 bp
->b_page_count
= page_count
;
270 if (page_count
<= XB_PAGES
) {
271 bp
->b_pages
= bp
->b_page_array
;
273 bp
->b_pages
= kmem_alloc(sizeof(struct page
*) *
274 page_count
, KM_NOFS
);
275 if (bp
->b_pages
== NULL
)
278 memset(bp
->b_pages
, 0, sizeof(struct page
*) * page_count
);
284 * Frees b_pages if it was allocated.
290 if (bp
->b_pages
!= bp
->b_page_array
) {
291 kmem_free(bp
->b_pages
);
297 * Releases the specified buffer.
299 * The modification state of any associated pages is left unchanged.
300 * The buffer must not be on any hash - use xfs_buf_rele instead for
301 * hashed and refcounted buffers
307 trace_xfs_buf_free(bp
, _RET_IP_
);
309 ASSERT(list_empty(&bp
->b_lru
));
311 if (bp
->b_flags
& _XBF_PAGES
) {
314 if (xfs_buf_is_vmapped(bp
))
315 vm_unmap_ram(bp
->b_addr
- bp
->b_offset
,
318 for (i
= 0; i
< bp
->b_page_count
; i
++) {
319 struct page
*page
= bp
->b_pages
[i
];
323 } else if (bp
->b_flags
& _XBF_KMEM
)
324 kmem_free(bp
->b_addr
);
325 _xfs_buf_free_pages(bp
);
326 xfs_buf_free_maps(bp
);
327 kmem_zone_free(xfs_buf_zone
, bp
);
331 * Allocates all the pages for buffer in question and builds it's page list.
334 xfs_buf_allocate_memory(
339 size_t nbytes
, offset
;
340 gfp_t gfp_mask
= xb_to_gfp(flags
);
341 unsigned short page_count
, i
;
342 xfs_off_t start
, end
;
346 * for buffers that are contained within a single page, just allocate
347 * the memory from the heap - there's no need for the complexity of
348 * page arrays to keep allocation down to order 0.
350 size
= BBTOB(bp
->b_length
);
351 if (size
< PAGE_SIZE
) {
352 bp
->b_addr
= kmem_alloc(size
, KM_NOFS
);
354 /* low memory - use alloc_page loop instead */
358 if (((unsigned long)(bp
->b_addr
+ size
- 1) & PAGE_MASK
) !=
359 ((unsigned long)bp
->b_addr
& PAGE_MASK
)) {
360 /* b_addr spans two pages - use alloc_page instead */
361 kmem_free(bp
->b_addr
);
365 bp
->b_offset
= offset_in_page(bp
->b_addr
);
366 bp
->b_pages
= bp
->b_page_array
;
367 bp
->b_pages
[0] = virt_to_page(bp
->b_addr
);
368 bp
->b_page_count
= 1;
369 bp
->b_flags
|= _XBF_KMEM
;
374 start
= BBTOB(bp
->b_maps
[0].bm_bn
) >> PAGE_SHIFT
;
375 end
= (BBTOB(bp
->b_maps
[0].bm_bn
+ bp
->b_length
) + PAGE_SIZE
- 1)
377 page_count
= end
- start
;
378 error
= _xfs_buf_get_pages(bp
, page_count
);
382 offset
= bp
->b_offset
;
383 bp
->b_flags
|= _XBF_PAGES
;
385 for (i
= 0; i
< bp
->b_page_count
; i
++) {
389 page
= alloc_page(gfp_mask
);
390 if (unlikely(page
== NULL
)) {
391 if (flags
& XBF_READ_AHEAD
) {
392 bp
->b_page_count
= i
;
398 * This could deadlock.
400 * But until all the XFS lowlevel code is revamped to
401 * handle buffer allocation failures we can't do much.
403 if (!(++retries
% 100))
405 "%s(%u) possible memory allocation deadlock in %s (mode:0x%x)",
406 current
->comm
, current
->pid
,
409 XFS_STATS_INC(bp
->b_target
->bt_mount
, xb_page_retries
);
410 congestion_wait(BLK_RW_ASYNC
, HZ
/50);
414 XFS_STATS_INC(bp
->b_target
->bt_mount
, xb_page_found
);
416 nbytes
= min_t(size_t, size
, PAGE_SIZE
- offset
);
418 bp
->b_pages
[i
] = page
;
424 for (i
= 0; i
< bp
->b_page_count
; i
++)
425 __free_page(bp
->b_pages
[i
]);
426 bp
->b_flags
&= ~_XBF_PAGES
;
431 * Map buffer into kernel address-space if necessary.
438 ASSERT(bp
->b_flags
& _XBF_PAGES
);
439 if (bp
->b_page_count
== 1) {
440 /* A single page buffer is always mappable */
441 bp
->b_addr
= page_address(bp
->b_pages
[0]) + bp
->b_offset
;
442 } else if (flags
& XBF_UNMAPPED
) {
449 * vm_map_ram() will allocate auxillary structures (e.g.
450 * pagetables) with GFP_KERNEL, yet we are likely to be under
451 * GFP_NOFS context here. Hence we need to tell memory reclaim
452 * that we are in such a context via PF_MEMALLOC_NOFS to prevent
453 * memory reclaim re-entering the filesystem here and
454 * potentially deadlocking.
456 nofs_flag
= memalloc_nofs_save();
458 bp
->b_addr
= vm_map_ram(bp
->b_pages
, bp
->b_page_count
,
463 } while (retried
++ <= 1);
464 memalloc_nofs_restore(nofs_flag
);
468 bp
->b_addr
+= bp
->b_offset
;
475 * Finding and Reading Buffers
479 struct rhashtable_compare_arg
*arg
,
482 const struct xfs_buf_map
*map
= arg
->key
;
483 const struct xfs_buf
*bp
= obj
;
486 * The key hashing in the lookup path depends on the key being the
487 * first element of the compare_arg, make sure to assert this.
489 BUILD_BUG_ON(offsetof(struct xfs_buf_map
, bm_bn
) != 0);
491 if (bp
->b_bn
!= map
->bm_bn
)
494 if (unlikely(bp
->b_length
!= map
->bm_len
)) {
496 * found a block number match. If the range doesn't
497 * match, the only way this is allowed is if the buffer
498 * in the cache is stale and the transaction that made
499 * it stale has not yet committed. i.e. we are
500 * reallocating a busy extent. Skip this buffer and
501 * continue searching for an exact match.
503 ASSERT(bp
->b_flags
& XBF_STALE
);
509 static const struct rhashtable_params xfs_buf_hash_params
= {
510 .min_size
= 32, /* empty AGs have minimal footprint */
512 .key_len
= sizeof(xfs_daddr_t
),
513 .key_offset
= offsetof(struct xfs_buf
, b_bn
),
514 .head_offset
= offsetof(struct xfs_buf
, b_rhash_head
),
515 .automatic_shrinking
= true,
516 .obj_cmpfn
= _xfs_buf_obj_cmp
,
521 struct xfs_perag
*pag
)
523 spin_lock_init(&pag
->pag_buf_lock
);
524 return rhashtable_init(&pag
->pag_buf_hash
, &xfs_buf_hash_params
);
528 xfs_buf_hash_destroy(
529 struct xfs_perag
*pag
)
531 rhashtable_destroy(&pag
->pag_buf_hash
);
535 * Look up, and creates if absent, a lockable buffer for
536 * a given range of an inode. The buffer is returned
537 * locked. No I/O is implied by this call.
541 struct xfs_buftarg
*btp
,
542 struct xfs_buf_map
*map
,
544 xfs_buf_flags_t flags
,
547 struct xfs_perag
*pag
;
549 struct xfs_buf_map cmap
= { .bm_bn
= map
[0].bm_bn
};
553 for (i
= 0; i
< nmaps
; i
++)
554 cmap
.bm_len
+= map
[i
].bm_len
;
556 /* Check for IOs smaller than the sector size / not sector aligned */
557 ASSERT(!(BBTOB(cmap
.bm_len
) < btp
->bt_meta_sectorsize
));
558 ASSERT(!(BBTOB(cmap
.bm_bn
) & (xfs_off_t
)btp
->bt_meta_sectormask
));
561 * Corrupted block numbers can get through to here, unfortunately, so we
562 * have to check that the buffer falls within the filesystem bounds.
564 eofs
= XFS_FSB_TO_BB(btp
->bt_mount
, btp
->bt_mount
->m_sb
.sb_dblocks
);
565 if (cmap
.bm_bn
< 0 || cmap
.bm_bn
>= eofs
) {
567 * XXX (dgc): we should really be returning -EFSCORRUPTED here,
568 * but none of the higher level infrastructure supports
569 * returning a specific error on buffer lookup failures.
571 xfs_alert(btp
->bt_mount
,
572 "%s: Block out of range: block 0x%llx, EOFS 0x%llx ",
573 __func__
, cmap
.bm_bn
, eofs
);
578 pag
= xfs_perag_get(btp
->bt_mount
,
579 xfs_daddr_to_agno(btp
->bt_mount
, cmap
.bm_bn
));
581 spin_lock(&pag
->pag_buf_lock
);
582 bp
= rhashtable_lookup_fast(&pag
->pag_buf_hash
, &cmap
,
583 xfs_buf_hash_params
);
585 atomic_inc(&bp
->b_hold
);
591 /* the buffer keeps the perag reference until it is freed */
593 rhashtable_insert_fast(&pag
->pag_buf_hash
,
594 &new_bp
->b_rhash_head
,
595 xfs_buf_hash_params
);
596 spin_unlock(&pag
->pag_buf_lock
);
598 XFS_STATS_INC(btp
->bt_mount
, xb_miss_locked
);
599 spin_unlock(&pag
->pag_buf_lock
);
605 spin_unlock(&pag
->pag_buf_lock
);
608 if (!xfs_buf_trylock(bp
)) {
609 if (flags
& XBF_TRYLOCK
) {
611 XFS_STATS_INC(btp
->bt_mount
, xb_busy_locked
);
615 XFS_STATS_INC(btp
->bt_mount
, xb_get_locked_waited
);
619 * if the buffer is stale, clear all the external state associated with
620 * it. We need to keep flags such as how we allocated the buffer memory
623 if (bp
->b_flags
& XBF_STALE
) {
624 ASSERT((bp
->b_flags
& _XBF_DELWRI_Q
) == 0);
625 ASSERT(bp
->b_iodone
== NULL
);
626 bp
->b_flags
&= _XBF_KMEM
| _XBF_PAGES
;
630 trace_xfs_buf_find(bp
, flags
, _RET_IP_
);
631 XFS_STATS_INC(btp
->bt_mount
, xb_get_locked
);
636 * Assembles a buffer covering the specified range. The code is optimised for
637 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
638 * more hits than misses.
642 struct xfs_buftarg
*target
,
643 struct xfs_buf_map
*map
,
645 xfs_buf_flags_t flags
)
648 struct xfs_buf
*new_bp
;
651 bp
= _xfs_buf_find(target
, map
, nmaps
, flags
, NULL
);
655 new_bp
= _xfs_buf_alloc(target
, map
, nmaps
, flags
);
656 if (unlikely(!new_bp
))
659 error
= xfs_buf_allocate_memory(new_bp
, flags
);
661 xfs_buf_free(new_bp
);
665 bp
= _xfs_buf_find(target
, map
, nmaps
, flags
, new_bp
);
667 xfs_buf_free(new_bp
);
672 xfs_buf_free(new_bp
);
676 error
= _xfs_buf_map_pages(bp
, flags
);
677 if (unlikely(error
)) {
678 xfs_warn(target
->bt_mount
,
679 "%s: failed to map pagesn", __func__
);
686 * Clear b_error if this is a lookup from a caller that doesn't expect
687 * valid data to be found in the buffer.
689 if (!(flags
& XBF_READ
))
690 xfs_buf_ioerror(bp
, 0);
692 XFS_STATS_INC(target
->bt_mount
, xb_get
);
693 trace_xfs_buf_get(bp
, flags
, _RET_IP_
);
700 xfs_buf_flags_t flags
)
702 ASSERT(!(flags
& XBF_WRITE
));
703 ASSERT(bp
->b_maps
[0].bm_bn
!= XFS_BUF_DADDR_NULL
);
705 bp
->b_flags
&= ~(XBF_WRITE
| XBF_ASYNC
| XBF_READ_AHEAD
);
706 bp
->b_flags
|= flags
& (XBF_READ
| XBF_ASYNC
| XBF_READ_AHEAD
);
708 if (flags
& XBF_ASYNC
) {
712 return xfs_buf_submit_wait(bp
);
717 struct xfs_buftarg
*target
,
718 struct xfs_buf_map
*map
,
720 xfs_buf_flags_t flags
,
721 const struct xfs_buf_ops
*ops
)
727 bp
= xfs_buf_get_map(target
, map
, nmaps
, flags
);
729 trace_xfs_buf_read(bp
, flags
, _RET_IP_
);
731 if (!(bp
->b_flags
& XBF_DONE
)) {
732 XFS_STATS_INC(target
->bt_mount
, xb_get_read
);
734 _xfs_buf_read(bp
, flags
);
735 } else if (flags
& XBF_ASYNC
) {
737 * Read ahead call which is already satisfied,
743 /* We do not want read in the flags */
744 bp
->b_flags
&= ~XBF_READ
;
752 * If we are not low on memory then do the readahead in a deadlock
756 xfs_buf_readahead_map(
757 struct xfs_buftarg
*target
,
758 struct xfs_buf_map
*map
,
760 const struct xfs_buf_ops
*ops
)
762 if (bdi_read_congested(target
->bt_bdev
->bd_bdi
))
765 xfs_buf_read_map(target
, map
, nmaps
,
766 XBF_TRYLOCK
|XBF_ASYNC
|XBF_READ_AHEAD
, ops
);
770 * Read an uncached buffer from disk. Allocates and returns a locked
771 * buffer containing the disk contents or nothing.
774 xfs_buf_read_uncached(
775 struct xfs_buftarg
*target
,
779 struct xfs_buf
**bpp
,
780 const struct xfs_buf_ops
*ops
)
786 bp
= xfs_buf_get_uncached(target
, numblks
, flags
);
790 /* set up the buffer for a read IO */
791 ASSERT(bp
->b_map_count
== 1);
792 bp
->b_bn
= XFS_BUF_DADDR_NULL
; /* always null for uncached buffers */
793 bp
->b_maps
[0].bm_bn
= daddr
;
794 bp
->b_flags
|= XBF_READ
;
797 xfs_buf_submit_wait(bp
);
799 int error
= bp
->b_error
;
809 * Return a buffer allocated as an empty buffer and associated to external
810 * memory via xfs_buf_associate_memory() back to it's empty state.
818 _xfs_buf_free_pages(bp
);
821 bp
->b_page_count
= 0;
823 bp
->b_length
= numblks
;
824 bp
->b_io_length
= numblks
;
826 ASSERT(bp
->b_map_count
== 1);
827 bp
->b_bn
= XFS_BUF_DADDR_NULL
;
828 bp
->b_maps
[0].bm_bn
= XFS_BUF_DADDR_NULL
;
829 bp
->b_maps
[0].bm_len
= bp
->b_length
;
832 static inline struct page
*
836 if ((!is_vmalloc_addr(addr
))) {
837 return virt_to_page(addr
);
839 return vmalloc_to_page(addr
);
844 xfs_buf_associate_memory(
851 unsigned long pageaddr
;
852 unsigned long offset
;
856 pageaddr
= (unsigned long)mem
& PAGE_MASK
;
857 offset
= (unsigned long)mem
- pageaddr
;
858 buflen
= PAGE_ALIGN(len
+ offset
);
859 page_count
= buflen
>> PAGE_SHIFT
;
861 /* Free any previous set of page pointers */
863 _xfs_buf_free_pages(bp
);
868 rval
= _xfs_buf_get_pages(bp
, page_count
);
872 bp
->b_offset
= offset
;
874 for (i
= 0; i
< bp
->b_page_count
; i
++) {
875 bp
->b_pages
[i
] = mem_to_page((void *)pageaddr
);
876 pageaddr
+= PAGE_SIZE
;
879 bp
->b_io_length
= BTOBB(len
);
880 bp
->b_length
= BTOBB(buflen
);
886 xfs_buf_get_uncached(
887 struct xfs_buftarg
*target
,
891 unsigned long page_count
;
894 DEFINE_SINGLE_BUF_MAP(map
, XFS_BUF_DADDR_NULL
, numblks
);
896 /* flags might contain irrelevant bits, pass only what we care about */
897 bp
= _xfs_buf_alloc(target
, &map
, 1, flags
& XBF_NO_IOACCT
);
898 if (unlikely(bp
== NULL
))
901 page_count
= PAGE_ALIGN(numblks
<< BBSHIFT
) >> PAGE_SHIFT
;
902 error
= _xfs_buf_get_pages(bp
, page_count
);
906 for (i
= 0; i
< page_count
; i
++) {
907 bp
->b_pages
[i
] = alloc_page(xb_to_gfp(flags
));
911 bp
->b_flags
|= _XBF_PAGES
;
913 error
= _xfs_buf_map_pages(bp
, 0);
914 if (unlikely(error
)) {
915 xfs_warn(target
->bt_mount
,
916 "%s: failed to map pages", __func__
);
920 trace_xfs_buf_get_uncached(bp
, _RET_IP_
);
925 __free_page(bp
->b_pages
[i
]);
926 _xfs_buf_free_pages(bp
);
928 xfs_buf_free_maps(bp
);
929 kmem_zone_free(xfs_buf_zone
, bp
);
935 * Increment reference count on buffer, to hold the buffer concurrently
936 * with another thread which may release (free) the buffer asynchronously.
937 * Must hold the buffer already to call this function.
943 trace_xfs_buf_hold(bp
, _RET_IP_
);
944 atomic_inc(&bp
->b_hold
);
948 * Release a hold on the specified buffer. If the hold count is 1, the buffer is
949 * placed on LRU or freed (depending on b_lru_ref).
955 struct xfs_perag
*pag
= bp
->b_pag
;
957 bool freebuf
= false;
959 trace_xfs_buf_rele(bp
, _RET_IP_
);
962 ASSERT(list_empty(&bp
->b_lru
));
963 if (atomic_dec_and_test(&bp
->b_hold
)) {
964 xfs_buf_ioacct_dec(bp
);
970 ASSERT(atomic_read(&bp
->b_hold
) > 0);
972 release
= atomic_dec_and_lock(&bp
->b_hold
, &pag
->pag_buf_lock
);
973 spin_lock(&bp
->b_lock
);
976 * Drop the in-flight state if the buffer is already on the LRU
977 * and it holds the only reference. This is racy because we
978 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
979 * ensures the decrement occurs only once per-buf.
981 if ((atomic_read(&bp
->b_hold
) == 1) && !list_empty(&bp
->b_lru
))
982 xfs_buf_ioacct_dec(bp
);
986 /* the last reference has been dropped ... */
987 xfs_buf_ioacct_dec(bp
);
988 if (!(bp
->b_flags
& XBF_STALE
) && atomic_read(&bp
->b_lru_ref
)) {
990 * If the buffer is added to the LRU take a new reference to the
991 * buffer for the LRU and clear the (now stale) dispose list
994 if (list_lru_add(&bp
->b_target
->bt_lru
, &bp
->b_lru
)) {
995 bp
->b_state
&= ~XFS_BSTATE_DISPOSE
;
996 atomic_inc(&bp
->b_hold
);
998 spin_unlock(&pag
->pag_buf_lock
);
1001 * most of the time buffers will already be removed from the
1002 * LRU, so optimise that case by checking for the
1003 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1004 * was on was the disposal list
1006 if (!(bp
->b_state
& XFS_BSTATE_DISPOSE
)) {
1007 list_lru_del(&bp
->b_target
->bt_lru
, &bp
->b_lru
);
1009 ASSERT(list_empty(&bp
->b_lru
));
1012 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
1013 rhashtable_remove_fast(&pag
->pag_buf_hash
, &bp
->b_rhash_head
,
1014 xfs_buf_hash_params
);
1015 spin_unlock(&pag
->pag_buf_lock
);
1021 spin_unlock(&bp
->b_lock
);
1029 * Lock a buffer object, if it is not already locked.
1031 * If we come across a stale, pinned, locked buffer, we know that we are
1032 * being asked to lock a buffer that has been reallocated. Because it is
1033 * pinned, we know that the log has not been pushed to disk and hence it
1034 * will still be locked. Rather than continuing to have trylock attempts
1035 * fail until someone else pushes the log, push it ourselves before
1036 * returning. This means that the xfsaild will not get stuck trying
1037 * to push on stale inode buffers.
1045 locked
= down_trylock(&bp
->b_sema
) == 0;
1048 trace_xfs_buf_trylock(bp
, _RET_IP_
);
1050 trace_xfs_buf_trylock_fail(bp
, _RET_IP_
);
1056 * Lock a buffer object.
1058 * If we come across a stale, pinned, locked buffer, we know that we
1059 * are being asked to lock a buffer that has been reallocated. Because
1060 * it is pinned, we know that the log has not been pushed to disk and
1061 * hence it will still be locked. Rather than sleeping until someone
1062 * else pushes the log, push it ourselves before trying to get the lock.
1068 trace_xfs_buf_lock(bp
, _RET_IP_
);
1070 if (atomic_read(&bp
->b_pin_count
) && (bp
->b_flags
& XBF_STALE
))
1071 xfs_log_force(bp
->b_target
->bt_mount
, 0);
1075 trace_xfs_buf_lock_done(bp
, _RET_IP_
);
1082 ASSERT(xfs_buf_islocked(bp
));
1087 trace_xfs_buf_unlock(bp
, _RET_IP_
);
1094 DECLARE_WAITQUEUE (wait
, current
);
1096 if (atomic_read(&bp
->b_pin_count
) == 0)
1099 add_wait_queue(&bp
->b_waiters
, &wait
);
1101 set_current_state(TASK_UNINTERRUPTIBLE
);
1102 if (atomic_read(&bp
->b_pin_count
) == 0)
1106 remove_wait_queue(&bp
->b_waiters
, &wait
);
1107 set_current_state(TASK_RUNNING
);
1111 * Buffer Utility Routines
1118 bool read
= bp
->b_flags
& XBF_READ
;
1120 trace_xfs_buf_iodone(bp
, _RET_IP_
);
1122 bp
->b_flags
&= ~(XBF_READ
| XBF_WRITE
| XBF_READ_AHEAD
);
1125 * Pull in IO completion errors now. We are guaranteed to be running
1126 * single threaded, so we don't need the lock to read b_io_error.
1128 if (!bp
->b_error
&& bp
->b_io_error
)
1129 xfs_buf_ioerror(bp
, bp
->b_io_error
);
1131 /* Only validate buffers that were read without errors */
1132 if (read
&& !bp
->b_error
&& bp
->b_ops
) {
1133 ASSERT(!bp
->b_iodone
);
1134 bp
->b_ops
->verify_read(bp
);
1138 bp
->b_flags
|= XBF_DONE
;
1141 (*(bp
->b_iodone
))(bp
);
1142 else if (bp
->b_flags
& XBF_ASYNC
)
1145 complete(&bp
->b_iowait
);
1150 struct work_struct
*work
)
1152 struct xfs_buf
*bp
=
1153 container_of(work
, xfs_buf_t
, b_ioend_work
);
1159 xfs_buf_ioend_async(
1162 INIT_WORK(&bp
->b_ioend_work
, xfs_buf_ioend_work
);
1163 queue_work(bp
->b_ioend_wq
, &bp
->b_ioend_work
);
1171 ASSERT(error
<= 0 && error
>= -1000);
1172 bp
->b_error
= error
;
1173 trace_xfs_buf_ioerror(bp
, error
, _RET_IP_
);
1177 xfs_buf_ioerror_alert(
1181 xfs_alert(bp
->b_target
->bt_mount
,
1182 "metadata I/O error: block 0x%llx (\"%s\") error %d numblks %d",
1183 (__uint64_t
)XFS_BUF_ADDR(bp
), func
, -bp
->b_error
, bp
->b_length
);
1192 ASSERT(xfs_buf_islocked(bp
));
1194 bp
->b_flags
|= XBF_WRITE
;
1195 bp
->b_flags
&= ~(XBF_ASYNC
| XBF_READ
| _XBF_DELWRI_Q
|
1196 XBF_WRITE_FAIL
| XBF_DONE
);
1198 error
= xfs_buf_submit_wait(bp
);
1200 xfs_force_shutdown(bp
->b_target
->bt_mount
,
1201 SHUTDOWN_META_IO_ERROR
);
1210 struct xfs_buf
*bp
= (struct xfs_buf
*)bio
->bi_private
;
1213 * don't overwrite existing errors - otherwise we can lose errors on
1214 * buffers that require multiple bios to complete.
1217 cmpxchg(&bp
->b_io_error
, 0, bio
->bi_error
);
1219 if (!bp
->b_error
&& xfs_buf_is_vmapped(bp
) && (bp
->b_flags
& XBF_READ
))
1220 invalidate_kernel_vmap_range(bp
->b_addr
, xfs_buf_vmap_len(bp
));
1222 if (atomic_dec_and_test(&bp
->b_io_remaining
) == 1)
1223 xfs_buf_ioend_async(bp
);
1228 xfs_buf_ioapply_map(
1237 int total_nr_pages
= bp
->b_page_count
;
1240 sector_t sector
= bp
->b_maps
[map
].bm_bn
;
1244 total_nr_pages
= bp
->b_page_count
;
1246 /* skip the pages in the buffer before the start offset */
1248 offset
= *buf_offset
;
1249 while (offset
>= PAGE_SIZE
) {
1251 offset
-= PAGE_SIZE
;
1255 * Limit the IO size to the length of the current vector, and update the
1256 * remaining IO count for the next time around.
1258 size
= min_t(int, BBTOB(bp
->b_maps
[map
].bm_len
), *count
);
1260 *buf_offset
+= size
;
1263 atomic_inc(&bp
->b_io_remaining
);
1264 nr_pages
= min(total_nr_pages
, BIO_MAX_PAGES
);
1266 bio
= bio_alloc(GFP_NOIO
, nr_pages
);
1267 bio
->bi_bdev
= bp
->b_target
->bt_bdev
;
1268 bio
->bi_iter
.bi_sector
= sector
;
1269 bio
->bi_end_io
= xfs_buf_bio_end_io
;
1270 bio
->bi_private
= bp
;
1271 bio_set_op_attrs(bio
, op
, op_flags
);
1273 for (; size
&& nr_pages
; nr_pages
--, page_index
++) {
1274 int rbytes
, nbytes
= PAGE_SIZE
- offset
;
1279 rbytes
= bio_add_page(bio
, bp
->b_pages
[page_index
], nbytes
,
1281 if (rbytes
< nbytes
)
1285 sector
+= BTOBB(nbytes
);
1290 if (likely(bio
->bi_iter
.bi_size
)) {
1291 if (xfs_buf_is_vmapped(bp
)) {
1292 flush_kernel_vmap_range(bp
->b_addr
,
1293 xfs_buf_vmap_len(bp
));
1300 * This is guaranteed not to be the last io reference count
1301 * because the caller (xfs_buf_submit) holds a count itself.
1303 atomic_dec(&bp
->b_io_remaining
);
1304 xfs_buf_ioerror(bp
, -EIO
);
1314 struct blk_plug plug
;
1322 * Make sure we capture only current IO errors rather than stale errors
1323 * left over from previous use of the buffer (e.g. failed readahead).
1328 * Initialize the I/O completion workqueue if we haven't yet or the
1329 * submitter has not opted to specify a custom one.
1331 if (!bp
->b_ioend_wq
)
1332 bp
->b_ioend_wq
= bp
->b_target
->bt_mount
->m_buf_workqueue
;
1334 if (bp
->b_flags
& XBF_WRITE
) {
1336 if (bp
->b_flags
& XBF_SYNCIO
)
1337 op_flags
= REQ_SYNC
;
1338 if (bp
->b_flags
& XBF_FUA
)
1339 op_flags
|= REQ_FUA
;
1340 if (bp
->b_flags
& XBF_FLUSH
)
1341 op_flags
|= REQ_PREFLUSH
;
1344 * Run the write verifier callback function if it exists. If
1345 * this function fails it will mark the buffer with an error and
1346 * the IO should not be dispatched.
1349 bp
->b_ops
->verify_write(bp
);
1351 xfs_force_shutdown(bp
->b_target
->bt_mount
,
1352 SHUTDOWN_CORRUPT_INCORE
);
1355 } else if (bp
->b_bn
!= XFS_BUF_DADDR_NULL
) {
1356 struct xfs_mount
*mp
= bp
->b_target
->bt_mount
;
1359 * non-crc filesystems don't attach verifiers during
1360 * log recovery, so don't warn for such filesystems.
1362 if (xfs_sb_version_hascrc(&mp
->m_sb
)) {
1364 "%s: no ops on block 0x%llx/0x%x",
1365 __func__
, bp
->b_bn
, bp
->b_length
);
1366 xfs_hex_dump(bp
->b_addr
, 64);
1370 } else if (bp
->b_flags
& XBF_READ_AHEAD
) {
1372 op_flags
= REQ_RAHEAD
;
1377 /* we only use the buffer cache for meta-data */
1378 op_flags
|= REQ_META
;
1381 * Walk all the vectors issuing IO on them. Set up the initial offset
1382 * into the buffer and the desired IO size before we start -
1383 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1386 offset
= bp
->b_offset
;
1387 size
= BBTOB(bp
->b_io_length
);
1388 blk_start_plug(&plug
);
1389 for (i
= 0; i
< bp
->b_map_count
; i
++) {
1390 xfs_buf_ioapply_map(bp
, i
, &offset
, &size
, op
, op_flags
);
1394 break; /* all done */
1396 blk_finish_plug(&plug
);
1400 * Asynchronous IO submission path. This transfers the buffer lock ownership and
1401 * the current reference to the IO. It is not safe to reference the buffer after
1402 * a call to this function unless the caller holds an additional reference
1409 trace_xfs_buf_submit(bp
, _RET_IP_
);
1411 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
1412 ASSERT(bp
->b_flags
& XBF_ASYNC
);
1414 /* on shutdown we stale and complete the buffer immediately */
1415 if (XFS_FORCED_SHUTDOWN(bp
->b_target
->bt_mount
)) {
1416 xfs_buf_ioerror(bp
, -EIO
);
1417 bp
->b_flags
&= ~XBF_DONE
;
1423 if (bp
->b_flags
& XBF_WRITE
)
1424 xfs_buf_wait_unpin(bp
);
1426 /* clear the internal error state to avoid spurious errors */
1430 * The caller's reference is released during I/O completion.
1431 * This occurs some time after the last b_io_remaining reference is
1432 * released, so after we drop our Io reference we have to have some
1433 * other reference to ensure the buffer doesn't go away from underneath
1434 * us. Take a direct reference to ensure we have safe access to the
1435 * buffer until we are finished with it.
1440 * Set the count to 1 initially, this will stop an I/O completion
1441 * callout which happens before we have started all the I/O from calling
1442 * xfs_buf_ioend too early.
1444 atomic_set(&bp
->b_io_remaining
, 1);
1445 xfs_buf_ioacct_inc(bp
);
1446 _xfs_buf_ioapply(bp
);
1449 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1450 * reference we took above. If we drop it to zero, run completion so
1451 * that we don't return to the caller with completion still pending.
1453 if (atomic_dec_and_test(&bp
->b_io_remaining
) == 1) {
1457 xfs_buf_ioend_async(bp
);
1461 /* Note: it is not safe to reference bp now we've dropped our ref */
1465 * Synchronous buffer IO submission path, read or write.
1468 xfs_buf_submit_wait(
1473 trace_xfs_buf_submit_wait(bp
, _RET_IP_
);
1475 ASSERT(!(bp
->b_flags
& (_XBF_DELWRI_Q
| XBF_ASYNC
)));
1477 if (XFS_FORCED_SHUTDOWN(bp
->b_target
->bt_mount
)) {
1478 xfs_buf_ioerror(bp
, -EIO
);
1480 bp
->b_flags
&= ~XBF_DONE
;
1484 if (bp
->b_flags
& XBF_WRITE
)
1485 xfs_buf_wait_unpin(bp
);
1487 /* clear the internal error state to avoid spurious errors */
1491 * For synchronous IO, the IO does not inherit the submitters reference
1492 * count, nor the buffer lock. Hence we cannot release the reference we
1493 * are about to take until we've waited for all IO completion to occur,
1494 * including any xfs_buf_ioend_async() work that may be pending.
1499 * Set the count to 1 initially, this will stop an I/O completion
1500 * callout which happens before we have started all the I/O from calling
1501 * xfs_buf_ioend too early.
1503 atomic_set(&bp
->b_io_remaining
, 1);
1504 _xfs_buf_ioapply(bp
);
1507 * make sure we run completion synchronously if it raced with us and is
1510 if (atomic_dec_and_test(&bp
->b_io_remaining
) == 1)
1513 /* wait for completion before gathering the error from the buffer */
1514 trace_xfs_buf_iowait(bp
, _RET_IP_
);
1515 wait_for_completion(&bp
->b_iowait
);
1516 trace_xfs_buf_iowait_done(bp
, _RET_IP_
);
1517 error
= bp
->b_error
;
1520 * all done now, we can release the hold that keeps the buffer
1521 * referenced for the entire IO.
1535 return bp
->b_addr
+ offset
;
1537 offset
+= bp
->b_offset
;
1538 page
= bp
->b_pages
[offset
>> PAGE_SHIFT
];
1539 return page_address(page
) + (offset
& (PAGE_SIZE
-1));
1543 * Move data into or out of a buffer.
1547 xfs_buf_t
*bp
, /* buffer to process */
1548 size_t boff
, /* starting buffer offset */
1549 size_t bsize
, /* length to copy */
1550 void *data
, /* data address */
1551 xfs_buf_rw_t mode
) /* read/write/zero flag */
1555 bend
= boff
+ bsize
;
1556 while (boff
< bend
) {
1558 int page_index
, page_offset
, csize
;
1560 page_index
= (boff
+ bp
->b_offset
) >> PAGE_SHIFT
;
1561 page_offset
= (boff
+ bp
->b_offset
) & ~PAGE_MASK
;
1562 page
= bp
->b_pages
[page_index
];
1563 csize
= min_t(size_t, PAGE_SIZE
- page_offset
,
1564 BBTOB(bp
->b_io_length
) - boff
);
1566 ASSERT((csize
+ page_offset
) <= PAGE_SIZE
);
1570 memset(page_address(page
) + page_offset
, 0, csize
);
1573 memcpy(data
, page_address(page
) + page_offset
, csize
);
1576 memcpy(page_address(page
) + page_offset
, data
, csize
);
1585 * Handling of buffer targets (buftargs).
1589 * Wait for any bufs with callbacks that have been submitted but have not yet
1590 * returned. These buffers will have an elevated hold count, so wait on those
1591 * while freeing all the buffers only held by the LRU.
1593 static enum lru_status
1594 xfs_buftarg_wait_rele(
1595 struct list_head
*item
,
1596 struct list_lru_one
*lru
,
1597 spinlock_t
*lru_lock
,
1601 struct xfs_buf
*bp
= container_of(item
, struct xfs_buf
, b_lru
);
1602 struct list_head
*dispose
= arg
;
1604 if (atomic_read(&bp
->b_hold
) > 1) {
1605 /* need to wait, so skip it this pass */
1606 trace_xfs_buf_wait_buftarg(bp
, _RET_IP_
);
1609 if (!spin_trylock(&bp
->b_lock
))
1613 * clear the LRU reference count so the buffer doesn't get
1614 * ignored in xfs_buf_rele().
1616 atomic_set(&bp
->b_lru_ref
, 0);
1617 bp
->b_state
|= XFS_BSTATE_DISPOSE
;
1618 list_lru_isolate_move(lru
, item
, dispose
);
1619 spin_unlock(&bp
->b_lock
);
1625 struct xfs_buftarg
*btp
)
1631 * First wait on the buftarg I/O count for all in-flight buffers to be
1632 * released. This is critical as new buffers do not make the LRU until
1633 * they are released.
1635 * Next, flush the buffer workqueue to ensure all completion processing
1636 * has finished. Just waiting on buffer locks is not sufficient for
1637 * async IO as the reference count held over IO is not released until
1638 * after the buffer lock is dropped. Hence we need to ensure here that
1639 * all reference counts have been dropped before we start walking the
1642 while (percpu_counter_sum(&btp
->bt_io_count
))
1644 flush_workqueue(btp
->bt_mount
->m_buf_workqueue
);
1646 /* loop until there is nothing left on the lru list. */
1647 while (list_lru_count(&btp
->bt_lru
)) {
1648 list_lru_walk(&btp
->bt_lru
, xfs_buftarg_wait_rele
,
1649 &dispose
, LONG_MAX
);
1651 while (!list_empty(&dispose
)) {
1653 bp
= list_first_entry(&dispose
, struct xfs_buf
, b_lru
);
1654 list_del_init(&bp
->b_lru
);
1655 if (bp
->b_flags
& XBF_WRITE_FAIL
) {
1656 xfs_alert(btp
->bt_mount
,
1657 "Corruption Alert: Buffer at block 0x%llx had permanent write failures!",
1658 (long long)bp
->b_bn
);
1659 xfs_alert(btp
->bt_mount
,
1660 "Please run xfs_repair to determine the extent of the problem.");
1669 static enum lru_status
1670 xfs_buftarg_isolate(
1671 struct list_head
*item
,
1672 struct list_lru_one
*lru
,
1673 spinlock_t
*lru_lock
,
1676 struct xfs_buf
*bp
= container_of(item
, struct xfs_buf
, b_lru
);
1677 struct list_head
*dispose
= arg
;
1680 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1681 * If we fail to get the lock, just skip it.
1683 if (!spin_trylock(&bp
->b_lock
))
1686 * Decrement the b_lru_ref count unless the value is already
1687 * zero. If the value is already zero, we need to reclaim the
1688 * buffer, otherwise it gets another trip through the LRU.
1690 if (!atomic_add_unless(&bp
->b_lru_ref
, -1, 0)) {
1691 spin_unlock(&bp
->b_lock
);
1695 bp
->b_state
|= XFS_BSTATE_DISPOSE
;
1696 list_lru_isolate_move(lru
, item
, dispose
);
1697 spin_unlock(&bp
->b_lock
);
1701 static unsigned long
1702 xfs_buftarg_shrink_scan(
1703 struct shrinker
*shrink
,
1704 struct shrink_control
*sc
)
1706 struct xfs_buftarg
*btp
= container_of(shrink
,
1707 struct xfs_buftarg
, bt_shrinker
);
1709 unsigned long freed
;
1711 freed
= list_lru_shrink_walk(&btp
->bt_lru
, sc
,
1712 xfs_buftarg_isolate
, &dispose
);
1714 while (!list_empty(&dispose
)) {
1716 bp
= list_first_entry(&dispose
, struct xfs_buf
, b_lru
);
1717 list_del_init(&bp
->b_lru
);
1724 static unsigned long
1725 xfs_buftarg_shrink_count(
1726 struct shrinker
*shrink
,
1727 struct shrink_control
*sc
)
1729 struct xfs_buftarg
*btp
= container_of(shrink
,
1730 struct xfs_buftarg
, bt_shrinker
);
1731 return list_lru_shrink_count(&btp
->bt_lru
, sc
);
1736 struct xfs_mount
*mp
,
1737 struct xfs_buftarg
*btp
)
1739 unregister_shrinker(&btp
->bt_shrinker
);
1740 ASSERT(percpu_counter_sum(&btp
->bt_io_count
) == 0);
1741 percpu_counter_destroy(&btp
->bt_io_count
);
1742 list_lru_destroy(&btp
->bt_lru
);
1744 xfs_blkdev_issue_flush(btp
);
1750 xfs_setsize_buftarg(
1752 unsigned int sectorsize
)
1754 /* Set up metadata sector size info */
1755 btp
->bt_meta_sectorsize
= sectorsize
;
1756 btp
->bt_meta_sectormask
= sectorsize
- 1;
1758 if (set_blocksize(btp
->bt_bdev
, sectorsize
)) {
1759 xfs_warn(btp
->bt_mount
,
1760 "Cannot set_blocksize to %u on device %pg",
1761 sectorsize
, btp
->bt_bdev
);
1765 /* Set up device logical sector size mask */
1766 btp
->bt_logical_sectorsize
= bdev_logical_block_size(btp
->bt_bdev
);
1767 btp
->bt_logical_sectormask
= bdev_logical_block_size(btp
->bt_bdev
) - 1;
1773 * When allocating the initial buffer target we have not yet
1774 * read in the superblock, so don't know what sized sectors
1775 * are being used at this early stage. Play safe.
1778 xfs_setsize_buftarg_early(
1780 struct block_device
*bdev
)
1782 return xfs_setsize_buftarg(btp
, bdev_logical_block_size(bdev
));
1787 struct xfs_mount
*mp
,
1788 struct block_device
*bdev
)
1792 btp
= kmem_zalloc(sizeof(*btp
), KM_SLEEP
| KM_NOFS
);
1795 btp
->bt_dev
= bdev
->bd_dev
;
1796 btp
->bt_bdev
= bdev
;
1798 if (xfs_setsize_buftarg_early(btp
, bdev
))
1801 if (list_lru_init(&btp
->bt_lru
))
1804 if (percpu_counter_init(&btp
->bt_io_count
, 0, GFP_KERNEL
))
1807 btp
->bt_shrinker
.count_objects
= xfs_buftarg_shrink_count
;
1808 btp
->bt_shrinker
.scan_objects
= xfs_buftarg_shrink_scan
;
1809 btp
->bt_shrinker
.seeks
= DEFAULT_SEEKS
;
1810 btp
->bt_shrinker
.flags
= SHRINKER_NUMA_AWARE
;
1811 register_shrinker(&btp
->bt_shrinker
);
1820 * Cancel a delayed write list.
1822 * Remove each buffer from the list, clear the delwri queue flag and drop the
1823 * associated buffer reference.
1826 xfs_buf_delwri_cancel(
1827 struct list_head
*list
)
1831 while (!list_empty(list
)) {
1832 bp
= list_first_entry(list
, struct xfs_buf
, b_list
);
1835 bp
->b_flags
&= ~_XBF_DELWRI_Q
;
1836 list_del_init(&bp
->b_list
);
1842 * Add a buffer to the delayed write list.
1844 * This queues a buffer for writeout if it hasn't already been. Note that
1845 * neither this routine nor the buffer list submission functions perform
1846 * any internal synchronization. It is expected that the lists are thread-local
1849 * Returns true if we queued up the buffer, or false if it already had
1850 * been on the buffer list.
1853 xfs_buf_delwri_queue(
1855 struct list_head
*list
)
1857 ASSERT(xfs_buf_islocked(bp
));
1858 ASSERT(!(bp
->b_flags
& XBF_READ
));
1861 * If the buffer is already marked delwri it already is queued up
1862 * by someone else for imediate writeout. Just ignore it in that
1865 if (bp
->b_flags
& _XBF_DELWRI_Q
) {
1866 trace_xfs_buf_delwri_queued(bp
, _RET_IP_
);
1870 trace_xfs_buf_delwri_queue(bp
, _RET_IP_
);
1873 * If a buffer gets written out synchronously or marked stale while it
1874 * is on a delwri list we lazily remove it. To do this, the other party
1875 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1876 * It remains referenced and on the list. In a rare corner case it
1877 * might get readded to a delwri list after the synchronous writeout, in
1878 * which case we need just need to re-add the flag here.
1880 bp
->b_flags
|= _XBF_DELWRI_Q
;
1881 if (list_empty(&bp
->b_list
)) {
1882 atomic_inc(&bp
->b_hold
);
1883 list_add_tail(&bp
->b_list
, list
);
1890 * Compare function is more complex than it needs to be because
1891 * the return value is only 32 bits and we are doing comparisons
1897 struct list_head
*a
,
1898 struct list_head
*b
)
1900 struct xfs_buf
*ap
= container_of(a
, struct xfs_buf
, b_list
);
1901 struct xfs_buf
*bp
= container_of(b
, struct xfs_buf
, b_list
);
1904 diff
= ap
->b_maps
[0].bm_bn
- bp
->b_maps
[0].bm_bn
;
1913 * submit buffers for write.
1915 * When we have a large buffer list, we do not want to hold all the buffers
1916 * locked while we block on the request queue waiting for IO dispatch. To avoid
1917 * this problem, we lock and submit buffers in groups of 50, thereby minimising
1918 * the lock hold times for lists which may contain thousands of objects.
1920 * To do this, we sort the buffer list before we walk the list to lock and
1921 * submit buffers, and we plug and unplug around each group of buffers we
1925 xfs_buf_delwri_submit_buffers(
1926 struct list_head
*buffer_list
,
1927 struct list_head
*wait_list
)
1929 struct xfs_buf
*bp
, *n
;
1930 LIST_HEAD (submit_list
);
1932 struct blk_plug plug
;
1934 list_sort(NULL
, buffer_list
, xfs_buf_cmp
);
1936 blk_start_plug(&plug
);
1937 list_for_each_entry_safe(bp
, n
, buffer_list
, b_list
) {
1939 if (xfs_buf_ispinned(bp
)) {
1943 if (!xfs_buf_trylock(bp
))
1950 * Someone else might have written the buffer synchronously or
1951 * marked it stale in the meantime. In that case only the
1952 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1953 * reference and remove it from the list here.
1955 if (!(bp
->b_flags
& _XBF_DELWRI_Q
)) {
1956 list_del_init(&bp
->b_list
);
1961 trace_xfs_buf_delwri_split(bp
, _RET_IP_
);
1964 * We do all IO submission async. This means if we need
1965 * to wait for IO completion we need to take an extra
1966 * reference so the buffer is still valid on the other
1967 * side. We need to move the buffer onto the io_list
1968 * at this point so the caller can still access it.
1970 bp
->b_flags
&= ~(_XBF_DELWRI_Q
| XBF_WRITE_FAIL
);
1971 bp
->b_flags
|= XBF_WRITE
| XBF_ASYNC
;
1974 list_move_tail(&bp
->b_list
, wait_list
);
1976 list_del_init(&bp
->b_list
);
1980 blk_finish_plug(&plug
);
1986 * Write out a buffer list asynchronously.
1988 * This will take the @buffer_list, write all non-locked and non-pinned buffers
1989 * out and not wait for I/O completion on any of the buffers. This interface
1990 * is only safely useable for callers that can track I/O completion by higher
1991 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
1995 xfs_buf_delwri_submit_nowait(
1996 struct list_head
*buffer_list
)
1998 return xfs_buf_delwri_submit_buffers(buffer_list
, NULL
);
2002 * Write out a buffer list synchronously.
2004 * This will take the @buffer_list, write all buffers out and wait for I/O
2005 * completion on all of the buffers. @buffer_list is consumed by the function,
2006 * so callers must have some other way of tracking buffers if they require such
2010 xfs_buf_delwri_submit(
2011 struct list_head
*buffer_list
)
2013 LIST_HEAD (wait_list
);
2014 int error
= 0, error2
;
2017 xfs_buf_delwri_submit_buffers(buffer_list
, &wait_list
);
2019 /* Wait for IO to complete. */
2020 while (!list_empty(&wait_list
)) {
2021 bp
= list_first_entry(&wait_list
, struct xfs_buf
, b_list
);
2023 list_del_init(&bp
->b_list
);
2025 /* locking the buffer will wait for async IO completion. */
2027 error2
= bp
->b_error
;
2039 xfs_buf_zone
= kmem_zone_init_flags(sizeof(xfs_buf_t
), "xfs_buf",
2040 KM_ZONE_HWALIGN
, NULL
);
2051 xfs_buf_terminate(void)
2053 kmem_zone_destroy(xfs_buf_zone
);