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>
40 #include "xfs_mount.h"
41 #include "xfs_trace.h"
43 static kmem_zone_t
*xfs_buf_zone
;
45 static struct workqueue_struct
*xfslogd_workqueue
;
47 #ifdef XFS_BUF_LOCK_TRACKING
48 # define XB_SET_OWNER(bp) ((bp)->b_last_holder = current->pid)
49 # define XB_CLEAR_OWNER(bp) ((bp)->b_last_holder = -1)
50 # define XB_GET_OWNER(bp) ((bp)->b_last_holder)
52 # define XB_SET_OWNER(bp) do { } while (0)
53 # define XB_CLEAR_OWNER(bp) do { } while (0)
54 # define XB_GET_OWNER(bp) do { } while (0)
57 #define xb_to_gfp(flags) \
58 ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : GFP_NOFS) | __GFP_NOWARN)
66 * Return true if the buffer is vmapped.
68 * b_addr is null if the buffer is not mapped, but the code is clever
69 * enough to know it doesn't have to map a single page, so the check has
70 * to be both for b_addr and bp->b_page_count > 1.
72 return bp
->b_addr
&& bp
->b_page_count
> 1;
79 return (bp
->b_page_count
* PAGE_SIZE
) - bp
->b_offset
;
83 * xfs_buf_lru_add - add a buffer to the LRU.
85 * The LRU takes a new reference to the buffer so that it will only be freed
86 * once the shrinker takes the buffer off the LRU.
92 struct xfs_buftarg
*btp
= bp
->b_target
;
94 spin_lock(&btp
->bt_lru_lock
);
95 if (list_empty(&bp
->b_lru
)) {
96 atomic_inc(&bp
->b_hold
);
97 list_add_tail(&bp
->b_lru
, &btp
->bt_lru
);
99 bp
->b_lru_flags
&= ~_XBF_LRU_DISPOSE
;
101 spin_unlock(&btp
->bt_lru_lock
);
105 * xfs_buf_lru_del - remove a buffer from the LRU
107 * The unlocked check is safe here because it only occurs when there are not
108 * b_lru_ref counts left on the inode under the pag->pag_buf_lock. it is there
109 * to optimise the shrinker removing the buffer from the LRU and calling
110 * xfs_buf_free(). i.e. it removes an unnecessary round trip on the
117 struct xfs_buftarg
*btp
= bp
->b_target
;
119 if (list_empty(&bp
->b_lru
))
122 spin_lock(&btp
->bt_lru_lock
);
123 if (!list_empty(&bp
->b_lru
)) {
124 list_del_init(&bp
->b_lru
);
127 spin_unlock(&btp
->bt_lru_lock
);
131 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
132 * b_lru_ref count so that the buffer is freed immediately when the buffer
133 * reference count falls to zero. If the buffer is already on the LRU, we need
134 * to remove the reference that LRU holds on the buffer.
136 * This prevents build-up of stale buffers on the LRU.
142 ASSERT(xfs_buf_islocked(bp
));
144 bp
->b_flags
|= XBF_STALE
;
147 * Clear the delwri status so that a delwri queue walker will not
148 * flush this buffer to disk now that it is stale. The delwri queue has
149 * a reference to the buffer, so this is safe to do.
151 bp
->b_flags
&= ~_XBF_DELWRI_Q
;
153 atomic_set(&(bp
)->b_lru_ref
, 0);
154 if (!list_empty(&bp
->b_lru
)) {
155 struct xfs_buftarg
*btp
= bp
->b_target
;
157 spin_lock(&btp
->bt_lru_lock
);
158 if (!list_empty(&bp
->b_lru
) &&
159 !(bp
->b_lru_flags
& _XBF_LRU_DISPOSE
)) {
160 list_del_init(&bp
->b_lru
);
162 atomic_dec(&bp
->b_hold
);
164 spin_unlock(&btp
->bt_lru_lock
);
166 ASSERT(atomic_read(&bp
->b_hold
) >= 1);
174 ASSERT(bp
->b_maps
== NULL
);
175 bp
->b_map_count
= map_count
;
177 if (map_count
== 1) {
178 bp
->b_maps
= &bp
->b_map
;
182 bp
->b_maps
= kmem_zalloc(map_count
* sizeof(struct xfs_buf_map
),
190 * Frees b_pages if it was allocated.
196 if (bp
->b_maps
!= &bp
->b_map
) {
197 kmem_free(bp
->b_maps
);
204 struct xfs_buftarg
*target
,
205 struct xfs_buf_map
*map
,
207 xfs_buf_flags_t flags
)
213 bp
= kmem_zone_zalloc(xfs_buf_zone
, KM_NOFS
);
218 * We don't want certain flags to appear in b_flags unless they are
219 * specifically set by later operations on the buffer.
221 flags
&= ~(XBF_UNMAPPED
| XBF_TRYLOCK
| XBF_ASYNC
| XBF_READ_AHEAD
);
223 atomic_set(&bp
->b_hold
, 1);
224 atomic_set(&bp
->b_lru_ref
, 1);
225 init_completion(&bp
->b_iowait
);
226 INIT_LIST_HEAD(&bp
->b_lru
);
227 INIT_LIST_HEAD(&bp
->b_list
);
228 RB_CLEAR_NODE(&bp
->b_rbnode
);
229 sema_init(&bp
->b_sema
, 0); /* held, no waiters */
231 bp
->b_target
= target
;
235 * Set length and io_length to the same value initially.
236 * I/O routines should use io_length, which will be the same in
237 * most cases but may be reset (e.g. XFS recovery).
239 error
= xfs_buf_get_maps(bp
, nmaps
);
241 kmem_zone_free(xfs_buf_zone
, bp
);
245 bp
->b_bn
= map
[0].bm_bn
;
247 for (i
= 0; i
< nmaps
; i
++) {
248 bp
->b_maps
[i
].bm_bn
= map
[i
].bm_bn
;
249 bp
->b_maps
[i
].bm_len
= map
[i
].bm_len
;
250 bp
->b_length
+= map
[i
].bm_len
;
252 bp
->b_io_length
= bp
->b_length
;
254 atomic_set(&bp
->b_pin_count
, 0);
255 init_waitqueue_head(&bp
->b_waiters
);
257 XFS_STATS_INC(xb_create
);
258 trace_xfs_buf_init(bp
, _RET_IP_
);
264 * Allocate a page array capable of holding a specified number
265 * of pages, and point the page buf at it.
271 xfs_buf_flags_t flags
)
273 /* Make sure that we have a page list */
274 if (bp
->b_pages
== NULL
) {
275 bp
->b_page_count
= page_count
;
276 if (page_count
<= XB_PAGES
) {
277 bp
->b_pages
= bp
->b_page_array
;
279 bp
->b_pages
= kmem_alloc(sizeof(struct page
*) *
280 page_count
, KM_NOFS
);
281 if (bp
->b_pages
== NULL
)
284 memset(bp
->b_pages
, 0, sizeof(struct page
*) * page_count
);
290 * Frees b_pages if it was allocated.
296 if (bp
->b_pages
!= bp
->b_page_array
) {
297 kmem_free(bp
->b_pages
);
303 * Releases the specified buffer.
305 * The modification state of any associated pages is left unchanged.
306 * The buffer most not be on any hash - use xfs_buf_rele instead for
307 * hashed and refcounted buffers
313 trace_xfs_buf_free(bp
, _RET_IP_
);
315 ASSERT(list_empty(&bp
->b_lru
));
317 if (bp
->b_flags
& _XBF_PAGES
) {
320 if (xfs_buf_is_vmapped(bp
))
321 vm_unmap_ram(bp
->b_addr
- bp
->b_offset
,
324 for (i
= 0; i
< bp
->b_page_count
; i
++) {
325 struct page
*page
= bp
->b_pages
[i
];
329 } else if (bp
->b_flags
& _XBF_KMEM
)
330 kmem_free(bp
->b_addr
);
331 _xfs_buf_free_pages(bp
);
332 xfs_buf_free_maps(bp
);
333 kmem_zone_free(xfs_buf_zone
, bp
);
337 * Allocates all the pages for buffer in question and builds it's page list.
340 xfs_buf_allocate_memory(
345 size_t nbytes
, offset
;
346 gfp_t gfp_mask
= xb_to_gfp(flags
);
347 unsigned short page_count
, i
;
348 xfs_off_t start
, end
;
352 * for buffers that are contained within a single page, just allocate
353 * the memory from the heap - there's no need for the complexity of
354 * page arrays to keep allocation down to order 0.
356 size
= BBTOB(bp
->b_length
);
357 if (size
< PAGE_SIZE
) {
358 bp
->b_addr
= kmem_alloc(size
, KM_NOFS
);
360 /* low memory - use alloc_page loop instead */
364 if (((unsigned long)(bp
->b_addr
+ size
- 1) & PAGE_MASK
) !=
365 ((unsigned long)bp
->b_addr
& PAGE_MASK
)) {
366 /* b_addr spans two pages - use alloc_page instead */
367 kmem_free(bp
->b_addr
);
371 bp
->b_offset
= offset_in_page(bp
->b_addr
);
372 bp
->b_pages
= bp
->b_page_array
;
373 bp
->b_pages
[0] = virt_to_page(bp
->b_addr
);
374 bp
->b_page_count
= 1;
375 bp
->b_flags
|= _XBF_KMEM
;
380 start
= BBTOB(bp
->b_map
.bm_bn
) >> PAGE_SHIFT
;
381 end
= (BBTOB(bp
->b_map
.bm_bn
+ bp
->b_length
) + PAGE_SIZE
- 1)
383 page_count
= end
- start
;
384 error
= _xfs_buf_get_pages(bp
, page_count
, flags
);
388 offset
= bp
->b_offset
;
389 bp
->b_flags
|= _XBF_PAGES
;
391 for (i
= 0; i
< bp
->b_page_count
; i
++) {
395 page
= alloc_page(gfp_mask
);
396 if (unlikely(page
== NULL
)) {
397 if (flags
& XBF_READ_AHEAD
) {
398 bp
->b_page_count
= i
;
404 * This could deadlock.
406 * But until all the XFS lowlevel code is revamped to
407 * handle buffer allocation failures we can't do much.
409 if (!(++retries
% 100))
411 "possible memory allocation deadlock in %s (mode:0x%x)",
414 XFS_STATS_INC(xb_page_retries
);
415 congestion_wait(BLK_RW_ASYNC
, HZ
/50);
419 XFS_STATS_INC(xb_page_found
);
421 nbytes
= min_t(size_t, size
, PAGE_SIZE
- offset
);
423 bp
->b_pages
[i
] = page
;
429 for (i
= 0; i
< bp
->b_page_count
; i
++)
430 __free_page(bp
->b_pages
[i
]);
435 * Map buffer into kernel address-space if necessary.
442 ASSERT(bp
->b_flags
& _XBF_PAGES
);
443 if (bp
->b_page_count
== 1) {
444 /* A single page buffer is always mappable */
445 bp
->b_addr
= page_address(bp
->b_pages
[0]) + bp
->b_offset
;
446 } else if (flags
& XBF_UNMAPPED
) {
452 bp
->b_addr
= vm_map_ram(bp
->b_pages
, bp
->b_page_count
,
457 } while (retried
++ <= 1);
461 bp
->b_addr
+= bp
->b_offset
;
468 * Finding and Reading Buffers
472 * Look up, and creates if absent, a lockable buffer for
473 * a given range of an inode. The buffer is returned
474 * locked. No I/O is implied by this call.
478 struct xfs_buftarg
*btp
,
479 struct xfs_buf_map
*map
,
481 xfs_buf_flags_t flags
,
485 struct xfs_perag
*pag
;
486 struct rb_node
**rbp
;
487 struct rb_node
*parent
;
489 xfs_daddr_t blkno
= map
[0].bm_bn
;
493 for (i
= 0; i
< nmaps
; i
++)
494 numblks
+= map
[i
].bm_len
;
495 numbytes
= BBTOB(numblks
);
497 /* Check for IOs smaller than the sector size / not sector aligned */
498 ASSERT(!(numbytes
< (1 << btp
->bt_sshift
)));
499 ASSERT(!(BBTOB(blkno
) & (xfs_off_t
)btp
->bt_smask
));
502 pag
= xfs_perag_get(btp
->bt_mount
,
503 xfs_daddr_to_agno(btp
->bt_mount
, blkno
));
506 spin_lock(&pag
->pag_buf_lock
);
507 rbp
= &pag
->pag_buf_tree
.rb_node
;
512 bp
= rb_entry(parent
, struct xfs_buf
, b_rbnode
);
514 if (blkno
< bp
->b_bn
)
515 rbp
= &(*rbp
)->rb_left
;
516 else if (blkno
> bp
->b_bn
)
517 rbp
= &(*rbp
)->rb_right
;
520 * found a block number match. If the range doesn't
521 * match, the only way this is allowed is if the buffer
522 * in the cache is stale and the transaction that made
523 * it stale has not yet committed. i.e. we are
524 * reallocating a busy extent. Skip this buffer and
525 * continue searching to the right for an exact match.
527 if (bp
->b_length
!= numblks
) {
528 ASSERT(bp
->b_flags
& XBF_STALE
);
529 rbp
= &(*rbp
)->rb_right
;
532 atomic_inc(&bp
->b_hold
);
539 rb_link_node(&new_bp
->b_rbnode
, parent
, rbp
);
540 rb_insert_color(&new_bp
->b_rbnode
, &pag
->pag_buf_tree
);
541 /* the buffer keeps the perag reference until it is freed */
543 spin_unlock(&pag
->pag_buf_lock
);
545 XFS_STATS_INC(xb_miss_locked
);
546 spin_unlock(&pag
->pag_buf_lock
);
552 spin_unlock(&pag
->pag_buf_lock
);
555 if (!xfs_buf_trylock(bp
)) {
556 if (flags
& XBF_TRYLOCK
) {
558 XFS_STATS_INC(xb_busy_locked
);
562 XFS_STATS_INC(xb_get_locked_waited
);
566 * if the buffer is stale, clear all the external state associated with
567 * it. We need to keep flags such as how we allocated the buffer memory
570 if (bp
->b_flags
& XBF_STALE
) {
571 ASSERT((bp
->b_flags
& _XBF_DELWRI_Q
) == 0);
572 bp
->b_flags
&= _XBF_KMEM
| _XBF_PAGES
;
575 trace_xfs_buf_find(bp
, flags
, _RET_IP_
);
576 XFS_STATS_INC(xb_get_locked
);
581 * Assembles a buffer covering the specified range. The code is optimised for
582 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
583 * more hits than misses.
587 struct xfs_buftarg
*target
,
588 struct xfs_buf_map
*map
,
590 xfs_buf_flags_t flags
)
593 struct xfs_buf
*new_bp
;
596 bp
= _xfs_buf_find(target
, map
, nmaps
, flags
, NULL
);
600 new_bp
= _xfs_buf_alloc(target
, map
, nmaps
, flags
);
601 if (unlikely(!new_bp
))
604 error
= xfs_buf_allocate_memory(new_bp
, flags
);
606 xfs_buf_free(new_bp
);
610 bp
= _xfs_buf_find(target
, map
, nmaps
, flags
, new_bp
);
612 xfs_buf_free(new_bp
);
617 xfs_buf_free(new_bp
);
621 error
= _xfs_buf_map_pages(bp
, flags
);
622 if (unlikely(error
)) {
623 xfs_warn(target
->bt_mount
,
624 "%s: failed to map pages\n", __func__
);
630 XFS_STATS_INC(xb_get
);
631 trace_xfs_buf_get(bp
, flags
, _RET_IP_
);
638 xfs_buf_flags_t flags
)
640 ASSERT(!(flags
& XBF_WRITE
));
641 ASSERT(bp
->b_map
.bm_bn
!= XFS_BUF_DADDR_NULL
);
643 bp
->b_flags
&= ~(XBF_WRITE
| XBF_ASYNC
| XBF_READ_AHEAD
);
644 bp
->b_flags
|= flags
& (XBF_READ
| XBF_ASYNC
| XBF_READ_AHEAD
);
646 xfs_buf_iorequest(bp
);
647 if (flags
& XBF_ASYNC
)
649 return xfs_buf_iowait(bp
);
654 struct xfs_buftarg
*target
,
655 struct xfs_buf_map
*map
,
657 xfs_buf_flags_t flags
)
663 bp
= xfs_buf_get_map(target
, map
, nmaps
, flags
);
665 trace_xfs_buf_read(bp
, flags
, _RET_IP_
);
667 if (!XFS_BUF_ISDONE(bp
)) {
668 XFS_STATS_INC(xb_get_read
);
669 _xfs_buf_read(bp
, flags
);
670 } else if (flags
& XBF_ASYNC
) {
672 * Read ahead call which is already satisfied,
678 /* We do not want read in the flags */
679 bp
->b_flags
&= ~XBF_READ
;
687 * If we are not low on memory then do the readahead in a deadlock
691 xfs_buf_readahead_map(
692 struct xfs_buftarg
*target
,
693 struct xfs_buf_map
*map
,
696 if (bdi_read_congested(target
->bt_bdi
))
699 xfs_buf_read_map(target
, map
, nmaps
,
700 XBF_TRYLOCK
|XBF_ASYNC
|XBF_READ_AHEAD
);
704 * Read an uncached buffer from disk. Allocates and returns a locked
705 * buffer containing the disk contents or nothing.
708 xfs_buf_read_uncached(
709 struct xfs_buftarg
*target
,
717 bp
= xfs_buf_get_uncached(target
, numblks
, flags
);
721 /* set up the buffer for a read IO */
722 ASSERT(bp
->b_map_count
== 1);
724 bp
->b_maps
[0].bm_bn
= daddr
;
725 bp
->b_flags
|= XBF_READ
;
727 xfsbdstrat(target
->bt_mount
, bp
);
728 error
= xfs_buf_iowait(bp
);
737 * Return a buffer allocated as an empty buffer and associated to external
738 * memory via xfs_buf_associate_memory() back to it's empty state.
746 _xfs_buf_free_pages(bp
);
749 bp
->b_page_count
= 0;
751 bp
->b_length
= numblks
;
752 bp
->b_io_length
= numblks
;
754 ASSERT(bp
->b_map_count
== 1);
755 bp
->b_bn
= XFS_BUF_DADDR_NULL
;
756 bp
->b_maps
[0].bm_bn
= XFS_BUF_DADDR_NULL
;
757 bp
->b_maps
[0].bm_len
= bp
->b_length
;
760 static inline struct page
*
764 if ((!is_vmalloc_addr(addr
))) {
765 return virt_to_page(addr
);
767 return vmalloc_to_page(addr
);
772 xfs_buf_associate_memory(
779 unsigned long pageaddr
;
780 unsigned long offset
;
784 pageaddr
= (unsigned long)mem
& PAGE_MASK
;
785 offset
= (unsigned long)mem
- pageaddr
;
786 buflen
= PAGE_ALIGN(len
+ offset
);
787 page_count
= buflen
>> PAGE_SHIFT
;
789 /* Free any previous set of page pointers */
791 _xfs_buf_free_pages(bp
);
796 rval
= _xfs_buf_get_pages(bp
, page_count
, 0);
800 bp
->b_offset
= offset
;
802 for (i
= 0; i
< bp
->b_page_count
; i
++) {
803 bp
->b_pages
[i
] = mem_to_page((void *)pageaddr
);
804 pageaddr
+= PAGE_SIZE
;
807 bp
->b_io_length
= BTOBB(len
);
808 bp
->b_length
= BTOBB(buflen
);
814 xfs_buf_get_uncached(
815 struct xfs_buftarg
*target
,
819 unsigned long page_count
;
822 DEFINE_SINGLE_BUF_MAP(map
, XFS_BUF_DADDR_NULL
, numblks
);
824 bp
= _xfs_buf_alloc(target
, &map
, 1, 0);
825 if (unlikely(bp
== NULL
))
828 page_count
= PAGE_ALIGN(numblks
<< BBSHIFT
) >> PAGE_SHIFT
;
829 error
= _xfs_buf_get_pages(bp
, page_count
, 0);
833 for (i
= 0; i
< page_count
; i
++) {
834 bp
->b_pages
[i
] = alloc_page(xb_to_gfp(flags
));
838 bp
->b_flags
|= _XBF_PAGES
;
840 error
= _xfs_buf_map_pages(bp
, 0);
841 if (unlikely(error
)) {
842 xfs_warn(target
->bt_mount
,
843 "%s: failed to map pages\n", __func__
);
847 trace_xfs_buf_get_uncached(bp
, _RET_IP_
);
852 __free_page(bp
->b_pages
[i
]);
853 _xfs_buf_free_pages(bp
);
855 xfs_buf_free_maps(bp
);
856 kmem_zone_free(xfs_buf_zone
, bp
);
862 * Increment reference count on buffer, to hold the buffer concurrently
863 * with another thread which may release (free) the buffer asynchronously.
864 * Must hold the buffer already to call this function.
870 trace_xfs_buf_hold(bp
, _RET_IP_
);
871 atomic_inc(&bp
->b_hold
);
875 * Releases a hold on the specified buffer. If the
876 * the hold count is 1, calls xfs_buf_free.
882 struct xfs_perag
*pag
= bp
->b_pag
;
884 trace_xfs_buf_rele(bp
, _RET_IP_
);
887 ASSERT(list_empty(&bp
->b_lru
));
888 ASSERT(RB_EMPTY_NODE(&bp
->b_rbnode
));
889 if (atomic_dec_and_test(&bp
->b_hold
))
894 ASSERT(!RB_EMPTY_NODE(&bp
->b_rbnode
));
896 ASSERT(atomic_read(&bp
->b_hold
) > 0);
897 if (atomic_dec_and_lock(&bp
->b_hold
, &pag
->pag_buf_lock
)) {
898 if (!(bp
->b_flags
& XBF_STALE
) &&
899 atomic_read(&bp
->b_lru_ref
)) {
901 spin_unlock(&pag
->pag_buf_lock
);
904 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
905 rb_erase(&bp
->b_rbnode
, &pag
->pag_buf_tree
);
906 spin_unlock(&pag
->pag_buf_lock
);
915 * Lock a buffer object, if it is not already locked.
917 * If we come across a stale, pinned, locked buffer, we know that we are
918 * being asked to lock a buffer that has been reallocated. Because it is
919 * pinned, we know that the log has not been pushed to disk and hence it
920 * will still be locked. Rather than continuing to have trylock attempts
921 * fail until someone else pushes the log, push it ourselves before
922 * returning. This means that the xfsaild will not get stuck trying
923 * to push on stale inode buffers.
931 locked
= down_trylock(&bp
->b_sema
) == 0;
934 else if (atomic_read(&bp
->b_pin_count
) && (bp
->b_flags
& XBF_STALE
))
935 xfs_log_force(bp
->b_target
->bt_mount
, 0);
937 trace_xfs_buf_trylock(bp
, _RET_IP_
);
942 * Lock a buffer object.
944 * If we come across a stale, pinned, locked buffer, we know that we
945 * are being asked to lock a buffer that has been reallocated. Because
946 * it is pinned, we know that the log has not been pushed to disk and
947 * hence it will still be locked. Rather than sleeping until someone
948 * else pushes the log, push it ourselves before trying to get the lock.
954 trace_xfs_buf_lock(bp
, _RET_IP_
);
956 if (atomic_read(&bp
->b_pin_count
) && (bp
->b_flags
& XBF_STALE
))
957 xfs_log_force(bp
->b_target
->bt_mount
, 0);
961 trace_xfs_buf_lock_done(bp
, _RET_IP_
);
971 trace_xfs_buf_unlock(bp
, _RET_IP_
);
978 DECLARE_WAITQUEUE (wait
, current
);
980 if (atomic_read(&bp
->b_pin_count
) == 0)
983 add_wait_queue(&bp
->b_waiters
, &wait
);
985 set_current_state(TASK_UNINTERRUPTIBLE
);
986 if (atomic_read(&bp
->b_pin_count
) == 0)
990 remove_wait_queue(&bp
->b_waiters
, &wait
);
991 set_current_state(TASK_RUNNING
);
995 * Buffer Utility Routines
1000 struct work_struct
*work
)
1003 container_of(work
, xfs_buf_t
, b_iodone_work
);
1006 (*(bp
->b_iodone
))(bp
);
1007 else if (bp
->b_flags
& XBF_ASYNC
)
1016 trace_xfs_buf_iodone(bp
, _RET_IP_
);
1018 bp
->b_flags
&= ~(XBF_READ
| XBF_WRITE
| XBF_READ_AHEAD
);
1019 if (bp
->b_error
== 0)
1020 bp
->b_flags
|= XBF_DONE
;
1022 if ((bp
->b_iodone
) || (bp
->b_flags
& XBF_ASYNC
)) {
1024 INIT_WORK(&bp
->b_iodone_work
, xfs_buf_iodone_work
);
1025 queue_work(xfslogd_workqueue
, &bp
->b_iodone_work
);
1027 xfs_buf_iodone_work(&bp
->b_iodone_work
);
1030 complete(&bp
->b_iowait
);
1039 ASSERT(error
>= 0 && error
<= 0xffff);
1040 bp
->b_error
= (unsigned short)error
;
1041 trace_xfs_buf_ioerror(bp
, error
, _RET_IP_
);
1045 xfs_buf_ioerror_alert(
1049 xfs_alert(bp
->b_target
->bt_mount
,
1050 "metadata I/O error: block 0x%llx (\"%s\") error %d numblks %d",
1051 (__uint64_t
)XFS_BUF_ADDR(bp
), func
, bp
->b_error
, bp
->b_length
);
1055 * Called when we want to stop a buffer from getting written or read.
1056 * We attach the EIO error, muck with its flags, and call xfs_buf_ioend
1057 * so that the proper iodone callbacks get called.
1063 #ifdef XFSERRORDEBUG
1064 ASSERT(XFS_BUF_ISREAD(bp
) || bp
->b_iodone
);
1068 * No need to wait until the buffer is unpinned, we aren't flushing it.
1070 xfs_buf_ioerror(bp
, EIO
);
1073 * We're calling xfs_buf_ioend, so delete XBF_DONE flag.
1079 xfs_buf_ioend(bp
, 0);
1085 * Same as xfs_bioerror, except that we are releasing the buffer
1086 * here ourselves, and avoiding the xfs_buf_ioend call.
1087 * This is meant for userdata errors; metadata bufs come with
1088 * iodone functions attached, so that we can track down errors.
1094 int64_t fl
= bp
->b_flags
;
1096 * No need to wait until the buffer is unpinned.
1097 * We aren't flushing it.
1099 * chunkhold expects B_DONE to be set, whether
1100 * we actually finish the I/O or not. We don't want to
1101 * change that interface.
1106 bp
->b_iodone
= NULL
;
1107 if (!(fl
& XBF_ASYNC
)) {
1109 * Mark b_error and B_ERROR _both_.
1110 * Lot's of chunkcache code assumes that.
1111 * There's no reason to mark error for
1114 xfs_buf_ioerror(bp
, EIO
);
1115 complete(&bp
->b_iowait
);
1127 if (XFS_FORCED_SHUTDOWN(bp
->b_target
->bt_mount
)) {
1128 trace_xfs_bdstrat_shut(bp
, _RET_IP_
);
1130 * Metadata write that didn't get logged but
1131 * written delayed anyway. These aren't associated
1132 * with a transaction, and can be ignored.
1134 if (!bp
->b_iodone
&& !XFS_BUF_ISREAD(bp
))
1135 return xfs_bioerror_relse(bp
);
1137 return xfs_bioerror(bp
);
1140 xfs_buf_iorequest(bp
);
1150 ASSERT(xfs_buf_islocked(bp
));
1152 bp
->b_flags
|= XBF_WRITE
;
1153 bp
->b_flags
&= ~(XBF_ASYNC
| XBF_READ
| _XBF_DELWRI_Q
);
1157 error
= xfs_buf_iowait(bp
);
1159 xfs_force_shutdown(bp
->b_target
->bt_mount
,
1160 SHUTDOWN_META_IO_ERROR
);
1166 * Wrapper around bdstrat so that we can stop data from going to disk in case
1167 * we are shutting down the filesystem. Typically user data goes thru this
1168 * path; one of the exceptions is the superblock.
1172 struct xfs_mount
*mp
,
1175 if (XFS_FORCED_SHUTDOWN(mp
)) {
1176 trace_xfs_bdstrat_shut(bp
, _RET_IP_
);
1177 xfs_bioerror_relse(bp
);
1181 xfs_buf_iorequest(bp
);
1189 if (atomic_dec_and_test(&bp
->b_io_remaining
) == 1)
1190 xfs_buf_ioend(bp
, schedule
);
1198 xfs_buf_t
*bp
= (xfs_buf_t
*)bio
->bi_private
;
1201 * don't overwrite existing errors - otherwise we can lose errors on
1202 * buffers that require multiple bios to complete.
1205 xfs_buf_ioerror(bp
, -error
);
1207 if (!bp
->b_error
&& xfs_buf_is_vmapped(bp
) && (bp
->b_flags
& XBF_READ
))
1208 invalidate_kernel_vmap_range(bp
->b_addr
, xfs_buf_vmap_len(bp
));
1210 _xfs_buf_ioend(bp
, 1);
1215 xfs_buf_ioapply_map(
1223 int total_nr_pages
= bp
->b_page_count
;
1226 sector_t sector
= bp
->b_maps
[map
].bm_bn
;
1230 total_nr_pages
= bp
->b_page_count
;
1232 /* skip the pages in the buffer before the start offset */
1234 offset
= *buf_offset
;
1235 while (offset
>= PAGE_SIZE
) {
1237 offset
-= PAGE_SIZE
;
1241 * Limit the IO size to the length of the current vector, and update the
1242 * remaining IO count for the next time around.
1244 size
= min_t(int, BBTOB(bp
->b_maps
[map
].bm_len
), *count
);
1246 *buf_offset
+= size
;
1249 atomic_inc(&bp
->b_io_remaining
);
1250 nr_pages
= BIO_MAX_SECTORS
>> (PAGE_SHIFT
- BBSHIFT
);
1251 if (nr_pages
> total_nr_pages
)
1252 nr_pages
= total_nr_pages
;
1254 bio
= bio_alloc(GFP_NOIO
, nr_pages
);
1255 bio
->bi_bdev
= bp
->b_target
->bt_bdev
;
1256 bio
->bi_sector
= sector
;
1257 bio
->bi_end_io
= xfs_buf_bio_end_io
;
1258 bio
->bi_private
= bp
;
1261 for (; size
&& nr_pages
; nr_pages
--, page_index
++) {
1262 int rbytes
, nbytes
= PAGE_SIZE
- offset
;
1267 rbytes
= bio_add_page(bio
, bp
->b_pages
[page_index
], nbytes
,
1269 if (rbytes
< nbytes
)
1273 sector
+= BTOBB(nbytes
);
1278 if (likely(bio
->bi_size
)) {
1279 if (xfs_buf_is_vmapped(bp
)) {
1280 flush_kernel_vmap_range(bp
->b_addr
,
1281 xfs_buf_vmap_len(bp
));
1283 submit_bio(rw
, bio
);
1288 * This is guaranteed not to be the last io reference count
1289 * because the caller (xfs_buf_iorequest) holds a count itself.
1291 atomic_dec(&bp
->b_io_remaining
);
1292 xfs_buf_ioerror(bp
, EIO
);
1302 struct blk_plug plug
;
1308 if (bp
->b_flags
& XBF_WRITE
) {
1309 if (bp
->b_flags
& XBF_SYNCIO
)
1313 if (bp
->b_flags
& XBF_FUA
)
1315 if (bp
->b_flags
& XBF_FLUSH
)
1317 } else if (bp
->b_flags
& XBF_READ_AHEAD
) {
1323 /* we only use the buffer cache for meta-data */
1327 * Walk all the vectors issuing IO on them. Set up the initial offset
1328 * into the buffer and the desired IO size before we start -
1329 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1332 offset
= bp
->b_offset
;
1333 size
= BBTOB(bp
->b_io_length
);
1334 blk_start_plug(&plug
);
1335 for (i
= 0; i
< bp
->b_map_count
; i
++) {
1336 xfs_buf_ioapply_map(bp
, i
, &offset
, &size
, rw
);
1340 break; /* all done */
1342 blk_finish_plug(&plug
);
1349 trace_xfs_buf_iorequest(bp
, _RET_IP_
);
1351 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
1353 if (bp
->b_flags
& XBF_WRITE
)
1354 xfs_buf_wait_unpin(bp
);
1357 /* Set the count to 1 initially, this will stop an I/O
1358 * completion callout which happens before we have started
1359 * all the I/O from calling xfs_buf_ioend too early.
1361 atomic_set(&bp
->b_io_remaining
, 1);
1362 _xfs_buf_ioapply(bp
);
1363 _xfs_buf_ioend(bp
, 1);
1369 * Waits for I/O to complete on the buffer supplied. It returns immediately if
1370 * no I/O is pending or there is already a pending error on the buffer. It
1371 * returns the I/O error code, if any, or 0 if there was no error.
1377 trace_xfs_buf_iowait(bp
, _RET_IP_
);
1380 wait_for_completion(&bp
->b_iowait
);
1382 trace_xfs_buf_iowait_done(bp
, _RET_IP_
);
1394 return bp
->b_addr
+ offset
;
1396 offset
+= bp
->b_offset
;
1397 page
= bp
->b_pages
[offset
>> PAGE_SHIFT
];
1398 return (xfs_caddr_t
)page_address(page
) + (offset
& (PAGE_SIZE
-1));
1402 * Move data into or out of a buffer.
1406 xfs_buf_t
*bp
, /* buffer to process */
1407 size_t boff
, /* starting buffer offset */
1408 size_t bsize
, /* length to copy */
1409 void *data
, /* data address */
1410 xfs_buf_rw_t mode
) /* read/write/zero flag */
1414 bend
= boff
+ bsize
;
1415 while (boff
< bend
) {
1417 int page_index
, page_offset
, csize
;
1419 page_index
= (boff
+ bp
->b_offset
) >> PAGE_SHIFT
;
1420 page_offset
= (boff
+ bp
->b_offset
) & ~PAGE_MASK
;
1421 page
= bp
->b_pages
[page_index
];
1422 csize
= min_t(size_t, PAGE_SIZE
- page_offset
,
1423 BBTOB(bp
->b_io_length
) - boff
);
1425 ASSERT((csize
+ page_offset
) <= PAGE_SIZE
);
1429 memset(page_address(page
) + page_offset
, 0, csize
);
1432 memcpy(data
, page_address(page
) + page_offset
, csize
);
1435 memcpy(page_address(page
) + page_offset
, data
, csize
);
1444 * Handling of buffer targets (buftargs).
1448 * Wait for any bufs with callbacks that have been submitted but have not yet
1449 * returned. These buffers will have an elevated hold count, so wait on those
1450 * while freeing all the buffers only held by the LRU.
1454 struct xfs_buftarg
*btp
)
1459 spin_lock(&btp
->bt_lru_lock
);
1460 while (!list_empty(&btp
->bt_lru
)) {
1461 bp
= list_first_entry(&btp
->bt_lru
, struct xfs_buf
, b_lru
);
1462 if (atomic_read(&bp
->b_hold
) > 1) {
1463 spin_unlock(&btp
->bt_lru_lock
);
1468 * clear the LRU reference count so the buffer doesn't get
1469 * ignored in xfs_buf_rele().
1471 atomic_set(&bp
->b_lru_ref
, 0);
1472 spin_unlock(&btp
->bt_lru_lock
);
1474 spin_lock(&btp
->bt_lru_lock
);
1476 spin_unlock(&btp
->bt_lru_lock
);
1481 struct shrinker
*shrink
,
1482 struct shrink_control
*sc
)
1484 struct xfs_buftarg
*btp
= container_of(shrink
,
1485 struct xfs_buftarg
, bt_shrinker
);
1487 int nr_to_scan
= sc
->nr_to_scan
;
1491 return btp
->bt_lru_nr
;
1493 spin_lock(&btp
->bt_lru_lock
);
1494 while (!list_empty(&btp
->bt_lru
)) {
1495 if (nr_to_scan
-- <= 0)
1498 bp
= list_first_entry(&btp
->bt_lru
, struct xfs_buf
, b_lru
);
1501 * Decrement the b_lru_ref count unless the value is already
1502 * zero. If the value is already zero, we need to reclaim the
1503 * buffer, otherwise it gets another trip through the LRU.
1505 if (!atomic_add_unless(&bp
->b_lru_ref
, -1, 0)) {
1506 list_move_tail(&bp
->b_lru
, &btp
->bt_lru
);
1511 * remove the buffer from the LRU now to avoid needing another
1512 * lock round trip inside xfs_buf_rele().
1514 list_move(&bp
->b_lru
, &dispose
);
1516 bp
->b_lru_flags
|= _XBF_LRU_DISPOSE
;
1518 spin_unlock(&btp
->bt_lru_lock
);
1520 while (!list_empty(&dispose
)) {
1521 bp
= list_first_entry(&dispose
, struct xfs_buf
, b_lru
);
1522 list_del_init(&bp
->b_lru
);
1526 return btp
->bt_lru_nr
;
1531 struct xfs_mount
*mp
,
1532 struct xfs_buftarg
*btp
)
1534 unregister_shrinker(&btp
->bt_shrinker
);
1536 if (mp
->m_flags
& XFS_MOUNT_BARRIER
)
1537 xfs_blkdev_issue_flush(btp
);
1543 xfs_setsize_buftarg_flags(
1545 unsigned int blocksize
,
1546 unsigned int sectorsize
,
1549 btp
->bt_bsize
= blocksize
;
1550 btp
->bt_sshift
= ffs(sectorsize
) - 1;
1551 btp
->bt_smask
= sectorsize
- 1;
1553 if (set_blocksize(btp
->bt_bdev
, sectorsize
)) {
1554 char name
[BDEVNAME_SIZE
];
1556 bdevname(btp
->bt_bdev
, name
);
1558 xfs_warn(btp
->bt_mount
,
1559 "Cannot set_blocksize to %u on device %s\n",
1568 * When allocating the initial buffer target we have not yet
1569 * read in the superblock, so don't know what sized sectors
1570 * are being used is at this early stage. Play safe.
1573 xfs_setsize_buftarg_early(
1575 struct block_device
*bdev
)
1577 return xfs_setsize_buftarg_flags(btp
,
1578 PAGE_SIZE
, bdev_logical_block_size(bdev
), 0);
1582 xfs_setsize_buftarg(
1584 unsigned int blocksize
,
1585 unsigned int sectorsize
)
1587 return xfs_setsize_buftarg_flags(btp
, blocksize
, sectorsize
, 1);
1592 struct xfs_mount
*mp
,
1593 struct block_device
*bdev
,
1599 btp
= kmem_zalloc(sizeof(*btp
), KM_SLEEP
);
1602 btp
->bt_dev
= bdev
->bd_dev
;
1603 btp
->bt_bdev
= bdev
;
1604 btp
->bt_bdi
= blk_get_backing_dev_info(bdev
);
1608 INIT_LIST_HEAD(&btp
->bt_lru
);
1609 spin_lock_init(&btp
->bt_lru_lock
);
1610 if (xfs_setsize_buftarg_early(btp
, bdev
))
1612 btp
->bt_shrinker
.shrink
= xfs_buftarg_shrink
;
1613 btp
->bt_shrinker
.seeks
= DEFAULT_SEEKS
;
1614 register_shrinker(&btp
->bt_shrinker
);
1623 * Add a buffer to the delayed write list.
1625 * This queues a buffer for writeout if it hasn't already been. Note that
1626 * neither this routine nor the buffer list submission functions perform
1627 * any internal synchronization. It is expected that the lists are thread-local
1630 * Returns true if we queued up the buffer, or false if it already had
1631 * been on the buffer list.
1634 xfs_buf_delwri_queue(
1636 struct list_head
*list
)
1638 ASSERT(xfs_buf_islocked(bp
));
1639 ASSERT(!(bp
->b_flags
& XBF_READ
));
1642 * If the buffer is already marked delwri it already is queued up
1643 * by someone else for imediate writeout. Just ignore it in that
1646 if (bp
->b_flags
& _XBF_DELWRI_Q
) {
1647 trace_xfs_buf_delwri_queued(bp
, _RET_IP_
);
1651 trace_xfs_buf_delwri_queue(bp
, _RET_IP_
);
1654 * If a buffer gets written out synchronously or marked stale while it
1655 * is on a delwri list we lazily remove it. To do this, the other party
1656 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1657 * It remains referenced and on the list. In a rare corner case it
1658 * might get readded to a delwri list after the synchronous writeout, in
1659 * which case we need just need to re-add the flag here.
1661 bp
->b_flags
|= _XBF_DELWRI_Q
;
1662 if (list_empty(&bp
->b_list
)) {
1663 atomic_inc(&bp
->b_hold
);
1664 list_add_tail(&bp
->b_list
, list
);
1671 * Compare function is more complex than it needs to be because
1672 * the return value is only 32 bits and we are doing comparisons
1678 struct list_head
*a
,
1679 struct list_head
*b
)
1681 struct xfs_buf
*ap
= container_of(a
, struct xfs_buf
, b_list
);
1682 struct xfs_buf
*bp
= container_of(b
, struct xfs_buf
, b_list
);
1685 diff
= ap
->b_map
.bm_bn
- bp
->b_map
.bm_bn
;
1694 __xfs_buf_delwri_submit(
1695 struct list_head
*buffer_list
,
1696 struct list_head
*io_list
,
1699 struct blk_plug plug
;
1700 struct xfs_buf
*bp
, *n
;
1703 list_for_each_entry_safe(bp
, n
, buffer_list
, b_list
) {
1705 if (xfs_buf_ispinned(bp
)) {
1709 if (!xfs_buf_trylock(bp
))
1716 * Someone else might have written the buffer synchronously or
1717 * marked it stale in the meantime. In that case only the
1718 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1719 * reference and remove it from the list here.
1721 if (!(bp
->b_flags
& _XBF_DELWRI_Q
)) {
1722 list_del_init(&bp
->b_list
);
1727 list_move_tail(&bp
->b_list
, io_list
);
1728 trace_xfs_buf_delwri_split(bp
, _RET_IP_
);
1731 list_sort(NULL
, io_list
, xfs_buf_cmp
);
1733 blk_start_plug(&plug
);
1734 list_for_each_entry_safe(bp
, n
, io_list
, b_list
) {
1735 bp
->b_flags
&= ~(_XBF_DELWRI_Q
| XBF_ASYNC
);
1736 bp
->b_flags
|= XBF_WRITE
;
1739 bp
->b_flags
|= XBF_ASYNC
;
1740 list_del_init(&bp
->b_list
);
1744 blk_finish_plug(&plug
);
1750 * Write out a buffer list asynchronously.
1752 * This will take the @buffer_list, write all non-locked and non-pinned buffers
1753 * out and not wait for I/O completion on any of the buffers. This interface
1754 * is only safely useable for callers that can track I/O completion by higher
1755 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
1759 xfs_buf_delwri_submit_nowait(
1760 struct list_head
*buffer_list
)
1762 LIST_HEAD (io_list
);
1763 return __xfs_buf_delwri_submit(buffer_list
, &io_list
, false);
1767 * Write out a buffer list synchronously.
1769 * This will take the @buffer_list, write all buffers out and wait for I/O
1770 * completion on all of the buffers. @buffer_list is consumed by the function,
1771 * so callers must have some other way of tracking buffers if they require such
1775 xfs_buf_delwri_submit(
1776 struct list_head
*buffer_list
)
1778 LIST_HEAD (io_list
);
1779 int error
= 0, error2
;
1782 __xfs_buf_delwri_submit(buffer_list
, &io_list
, true);
1784 /* Wait for IO to complete. */
1785 while (!list_empty(&io_list
)) {
1786 bp
= list_first_entry(&io_list
, struct xfs_buf
, b_list
);
1788 list_del_init(&bp
->b_list
);
1789 error2
= xfs_buf_iowait(bp
);
1801 xfs_buf_zone
= kmem_zone_init_flags(sizeof(xfs_buf_t
), "xfs_buf",
1802 KM_ZONE_HWALIGN
, NULL
);
1806 xfslogd_workqueue
= alloc_workqueue("xfslogd",
1807 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 1);
1808 if (!xfslogd_workqueue
)
1809 goto out_free_buf_zone
;
1814 kmem_zone_destroy(xfs_buf_zone
);
1820 xfs_buf_terminate(void)
1822 destroy_workqueue(xfslogd_workqueue
);
1823 kmem_zone_destroy(xfs_buf_zone
);
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