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_maps
[0].bm_bn
) >> PAGE_SHIFT
;
381 end
= (BBTOB(bp
->b_maps
[0].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
;
494 for (i
= 0; i
< nmaps
; i
++)
495 numblks
+= map
[i
].bm_len
;
496 numbytes
= BBTOB(numblks
);
498 /* Check for IOs smaller than the sector size / not sector aligned */
499 ASSERT(!(numbytes
< (1 << btp
->bt_sshift
)));
500 ASSERT(!(BBTOB(blkno
) & (xfs_off_t
)btp
->bt_smask
));
503 * Corrupted block numbers can get through to here, unfortunately, so we
504 * have to check that the buffer falls within the filesystem bounds.
506 eofs
= XFS_FSB_TO_BB(btp
->bt_mount
, btp
->bt_mount
->m_sb
.sb_dblocks
);
509 * XXX (dgc): we should really be returning EFSCORRUPTED here,
510 * but none of the higher level infrastructure supports
511 * returning a specific error on buffer lookup failures.
513 xfs_alert(btp
->bt_mount
,
514 "%s: Block out of range: block 0x%llx, EOFS 0x%llx ",
515 __func__
, blkno
, eofs
);
520 pag
= xfs_perag_get(btp
->bt_mount
,
521 xfs_daddr_to_agno(btp
->bt_mount
, blkno
));
524 spin_lock(&pag
->pag_buf_lock
);
525 rbp
= &pag
->pag_buf_tree
.rb_node
;
530 bp
= rb_entry(parent
, struct xfs_buf
, b_rbnode
);
532 if (blkno
< bp
->b_bn
)
533 rbp
= &(*rbp
)->rb_left
;
534 else if (blkno
> bp
->b_bn
)
535 rbp
= &(*rbp
)->rb_right
;
538 * found a block number match. If the range doesn't
539 * match, the only way this is allowed is if the buffer
540 * in the cache is stale and the transaction that made
541 * it stale has not yet committed. i.e. we are
542 * reallocating a busy extent. Skip this buffer and
543 * continue searching to the right for an exact match.
545 if (bp
->b_length
!= numblks
) {
546 ASSERT(bp
->b_flags
& XBF_STALE
);
547 rbp
= &(*rbp
)->rb_right
;
550 atomic_inc(&bp
->b_hold
);
557 rb_link_node(&new_bp
->b_rbnode
, parent
, rbp
);
558 rb_insert_color(&new_bp
->b_rbnode
, &pag
->pag_buf_tree
);
559 /* the buffer keeps the perag reference until it is freed */
561 spin_unlock(&pag
->pag_buf_lock
);
563 XFS_STATS_INC(xb_miss_locked
);
564 spin_unlock(&pag
->pag_buf_lock
);
570 spin_unlock(&pag
->pag_buf_lock
);
573 if (!xfs_buf_trylock(bp
)) {
574 if (flags
& XBF_TRYLOCK
) {
576 XFS_STATS_INC(xb_busy_locked
);
580 XFS_STATS_INC(xb_get_locked_waited
);
584 * if the buffer is stale, clear all the external state associated with
585 * it. We need to keep flags such as how we allocated the buffer memory
588 if (bp
->b_flags
& XBF_STALE
) {
589 ASSERT((bp
->b_flags
& _XBF_DELWRI_Q
) == 0);
590 ASSERT(bp
->b_iodone
== NULL
);
591 bp
->b_flags
&= _XBF_KMEM
| _XBF_PAGES
;
595 trace_xfs_buf_find(bp
, flags
, _RET_IP_
);
596 XFS_STATS_INC(xb_get_locked
);
601 * Assembles a buffer covering the specified range. The code is optimised for
602 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
603 * more hits than misses.
607 struct xfs_buftarg
*target
,
608 struct xfs_buf_map
*map
,
610 xfs_buf_flags_t flags
)
613 struct xfs_buf
*new_bp
;
616 bp
= _xfs_buf_find(target
, map
, nmaps
, flags
, NULL
);
620 new_bp
= _xfs_buf_alloc(target
, map
, nmaps
, flags
);
621 if (unlikely(!new_bp
))
624 error
= xfs_buf_allocate_memory(new_bp
, flags
);
626 xfs_buf_free(new_bp
);
630 bp
= _xfs_buf_find(target
, map
, nmaps
, flags
, new_bp
);
632 xfs_buf_free(new_bp
);
637 xfs_buf_free(new_bp
);
641 error
= _xfs_buf_map_pages(bp
, flags
);
642 if (unlikely(error
)) {
643 xfs_warn(target
->bt_mount
,
644 "%s: failed to map pages\n", __func__
);
650 XFS_STATS_INC(xb_get
);
651 trace_xfs_buf_get(bp
, flags
, _RET_IP_
);
658 xfs_buf_flags_t flags
)
660 ASSERT(!(flags
& XBF_WRITE
));
661 ASSERT(bp
->b_maps
[0].bm_bn
!= XFS_BUF_DADDR_NULL
);
663 bp
->b_flags
&= ~(XBF_WRITE
| XBF_ASYNC
| XBF_READ_AHEAD
);
664 bp
->b_flags
|= flags
& (XBF_READ
| XBF_ASYNC
| XBF_READ_AHEAD
);
666 xfs_buf_iorequest(bp
);
667 if (flags
& XBF_ASYNC
)
669 return xfs_buf_iowait(bp
);
674 struct xfs_buftarg
*target
,
675 struct xfs_buf_map
*map
,
677 xfs_buf_flags_t flags
,
678 const struct xfs_buf_ops
*ops
)
684 bp
= xfs_buf_get_map(target
, map
, nmaps
, flags
);
686 trace_xfs_buf_read(bp
, flags
, _RET_IP_
);
688 if (!XFS_BUF_ISDONE(bp
)) {
689 XFS_STATS_INC(xb_get_read
);
691 _xfs_buf_read(bp
, flags
);
692 } else if (flags
& XBF_ASYNC
) {
694 * Read ahead call which is already satisfied,
700 /* We do not want read in the flags */
701 bp
->b_flags
&= ~XBF_READ
;
709 * If we are not low on memory then do the readahead in a deadlock
713 xfs_buf_readahead_map(
714 struct xfs_buftarg
*target
,
715 struct xfs_buf_map
*map
,
717 const struct xfs_buf_ops
*ops
)
719 if (bdi_read_congested(target
->bt_bdi
))
722 xfs_buf_read_map(target
, map
, nmaps
,
723 XBF_TRYLOCK
|XBF_ASYNC
|XBF_READ_AHEAD
, ops
);
727 * Read an uncached buffer from disk. Allocates and returns a locked
728 * buffer containing the disk contents or nothing.
731 xfs_buf_read_uncached(
732 struct xfs_buftarg
*target
,
736 const struct xfs_buf_ops
*ops
)
740 bp
= xfs_buf_get_uncached(target
, numblks
, flags
);
744 /* set up the buffer for a read IO */
745 ASSERT(bp
->b_map_count
== 1);
747 bp
->b_maps
[0].bm_bn
= daddr
;
748 bp
->b_flags
|= XBF_READ
;
751 xfsbdstrat(target
->bt_mount
, bp
);
757 * Return a buffer allocated as an empty buffer and associated to external
758 * memory via xfs_buf_associate_memory() back to it's empty state.
766 _xfs_buf_free_pages(bp
);
769 bp
->b_page_count
= 0;
771 bp
->b_length
= numblks
;
772 bp
->b_io_length
= numblks
;
774 ASSERT(bp
->b_map_count
== 1);
775 bp
->b_bn
= XFS_BUF_DADDR_NULL
;
776 bp
->b_maps
[0].bm_bn
= XFS_BUF_DADDR_NULL
;
777 bp
->b_maps
[0].bm_len
= bp
->b_length
;
780 static inline struct page
*
784 if ((!is_vmalloc_addr(addr
))) {
785 return virt_to_page(addr
);
787 return vmalloc_to_page(addr
);
792 xfs_buf_associate_memory(
799 unsigned long pageaddr
;
800 unsigned long offset
;
804 pageaddr
= (unsigned long)mem
& PAGE_MASK
;
805 offset
= (unsigned long)mem
- pageaddr
;
806 buflen
= PAGE_ALIGN(len
+ offset
);
807 page_count
= buflen
>> PAGE_SHIFT
;
809 /* Free any previous set of page pointers */
811 _xfs_buf_free_pages(bp
);
816 rval
= _xfs_buf_get_pages(bp
, page_count
, 0);
820 bp
->b_offset
= offset
;
822 for (i
= 0; i
< bp
->b_page_count
; i
++) {
823 bp
->b_pages
[i
] = mem_to_page((void *)pageaddr
);
824 pageaddr
+= PAGE_SIZE
;
827 bp
->b_io_length
= BTOBB(len
);
828 bp
->b_length
= BTOBB(buflen
);
834 xfs_buf_get_uncached(
835 struct xfs_buftarg
*target
,
839 unsigned long page_count
;
842 DEFINE_SINGLE_BUF_MAP(map
, XFS_BUF_DADDR_NULL
, numblks
);
844 bp
= _xfs_buf_alloc(target
, &map
, 1, 0);
845 if (unlikely(bp
== NULL
))
848 page_count
= PAGE_ALIGN(numblks
<< BBSHIFT
) >> PAGE_SHIFT
;
849 error
= _xfs_buf_get_pages(bp
, page_count
, 0);
853 for (i
= 0; i
< page_count
; i
++) {
854 bp
->b_pages
[i
] = alloc_page(xb_to_gfp(flags
));
858 bp
->b_flags
|= _XBF_PAGES
;
860 error
= _xfs_buf_map_pages(bp
, 0);
861 if (unlikely(error
)) {
862 xfs_warn(target
->bt_mount
,
863 "%s: failed to map pages\n", __func__
);
867 trace_xfs_buf_get_uncached(bp
, _RET_IP_
);
872 __free_page(bp
->b_pages
[i
]);
873 _xfs_buf_free_pages(bp
);
875 xfs_buf_free_maps(bp
);
876 kmem_zone_free(xfs_buf_zone
, bp
);
882 * Increment reference count on buffer, to hold the buffer concurrently
883 * with another thread which may release (free) the buffer asynchronously.
884 * Must hold the buffer already to call this function.
890 trace_xfs_buf_hold(bp
, _RET_IP_
);
891 atomic_inc(&bp
->b_hold
);
895 * Releases a hold on the specified buffer. If the
896 * the hold count is 1, calls xfs_buf_free.
902 struct xfs_perag
*pag
= bp
->b_pag
;
904 trace_xfs_buf_rele(bp
, _RET_IP_
);
907 ASSERT(list_empty(&bp
->b_lru
));
908 ASSERT(RB_EMPTY_NODE(&bp
->b_rbnode
));
909 if (atomic_dec_and_test(&bp
->b_hold
))
914 ASSERT(!RB_EMPTY_NODE(&bp
->b_rbnode
));
916 ASSERT(atomic_read(&bp
->b_hold
) > 0);
917 if (atomic_dec_and_lock(&bp
->b_hold
, &pag
->pag_buf_lock
)) {
918 if (!(bp
->b_flags
& XBF_STALE
) &&
919 atomic_read(&bp
->b_lru_ref
)) {
921 spin_unlock(&pag
->pag_buf_lock
);
924 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
925 rb_erase(&bp
->b_rbnode
, &pag
->pag_buf_tree
);
926 spin_unlock(&pag
->pag_buf_lock
);
935 * Lock a buffer object, if it is not already locked.
937 * If we come across a stale, pinned, locked buffer, we know that we are
938 * being asked to lock a buffer that has been reallocated. Because it is
939 * pinned, we know that the log has not been pushed to disk and hence it
940 * will still be locked. Rather than continuing to have trylock attempts
941 * fail until someone else pushes the log, push it ourselves before
942 * returning. This means that the xfsaild will not get stuck trying
943 * to push on stale inode buffers.
951 locked
= down_trylock(&bp
->b_sema
) == 0;
955 trace_xfs_buf_trylock(bp
, _RET_IP_
);
960 * Lock a buffer object.
962 * If we come across a stale, pinned, locked buffer, we know that we
963 * are being asked to lock a buffer that has been reallocated. Because
964 * it is pinned, we know that the log has not been pushed to disk and
965 * hence it will still be locked. Rather than sleeping until someone
966 * else pushes the log, push it ourselves before trying to get the lock.
972 trace_xfs_buf_lock(bp
, _RET_IP_
);
974 if (atomic_read(&bp
->b_pin_count
) && (bp
->b_flags
& XBF_STALE
))
975 xfs_log_force(bp
->b_target
->bt_mount
, 0);
979 trace_xfs_buf_lock_done(bp
, _RET_IP_
);
989 trace_xfs_buf_unlock(bp
, _RET_IP_
);
996 DECLARE_WAITQUEUE (wait
, current
);
998 if (atomic_read(&bp
->b_pin_count
) == 0)
1001 add_wait_queue(&bp
->b_waiters
, &wait
);
1003 set_current_state(TASK_UNINTERRUPTIBLE
);
1004 if (atomic_read(&bp
->b_pin_count
) == 0)
1008 remove_wait_queue(&bp
->b_waiters
, &wait
);
1009 set_current_state(TASK_RUNNING
);
1013 * Buffer Utility Routines
1017 xfs_buf_iodone_work(
1018 struct work_struct
*work
)
1020 struct xfs_buf
*bp
=
1021 container_of(work
, xfs_buf_t
, b_iodone_work
);
1022 bool read
= !!(bp
->b_flags
& XBF_READ
);
1024 bp
->b_flags
&= ~(XBF_READ
| XBF_WRITE
| XBF_READ_AHEAD
);
1025 if (read
&& bp
->b_ops
)
1026 bp
->b_ops
->verify_read(bp
);
1029 (*(bp
->b_iodone
))(bp
);
1030 else if (bp
->b_flags
& XBF_ASYNC
)
1033 ASSERT(read
&& bp
->b_ops
);
1034 complete(&bp
->b_iowait
);
1043 bool read
= !!(bp
->b_flags
& XBF_READ
);
1045 trace_xfs_buf_iodone(bp
, _RET_IP_
);
1047 if (bp
->b_error
== 0)
1048 bp
->b_flags
|= XBF_DONE
;
1050 if (bp
->b_iodone
|| (read
&& bp
->b_ops
) || (bp
->b_flags
& XBF_ASYNC
)) {
1052 INIT_WORK(&bp
->b_iodone_work
, xfs_buf_iodone_work
);
1053 queue_work(xfslogd_workqueue
, &bp
->b_iodone_work
);
1055 xfs_buf_iodone_work(&bp
->b_iodone_work
);
1058 bp
->b_flags
&= ~(XBF_READ
| XBF_WRITE
| XBF_READ_AHEAD
);
1059 complete(&bp
->b_iowait
);
1068 ASSERT(error
>= 0 && error
<= 0xffff);
1069 bp
->b_error
= (unsigned short)error
;
1070 trace_xfs_buf_ioerror(bp
, error
, _RET_IP_
);
1074 xfs_buf_ioerror_alert(
1078 xfs_alert(bp
->b_target
->bt_mount
,
1079 "metadata I/O error: block 0x%llx (\"%s\") error %d numblks %d",
1080 (__uint64_t
)XFS_BUF_ADDR(bp
), func
, bp
->b_error
, bp
->b_length
);
1084 * Called when we want to stop a buffer from getting written or read.
1085 * We attach the EIO error, muck with its flags, and call xfs_buf_ioend
1086 * so that the proper iodone callbacks get called.
1092 #ifdef XFSERRORDEBUG
1093 ASSERT(XFS_BUF_ISREAD(bp
) || bp
->b_iodone
);
1097 * No need to wait until the buffer is unpinned, we aren't flushing it.
1099 xfs_buf_ioerror(bp
, EIO
);
1102 * We're calling xfs_buf_ioend, so delete XBF_DONE flag.
1108 xfs_buf_ioend(bp
, 0);
1114 * Same as xfs_bioerror, except that we are releasing the buffer
1115 * here ourselves, and avoiding the xfs_buf_ioend call.
1116 * This is meant for userdata errors; metadata bufs come with
1117 * iodone functions attached, so that we can track down errors.
1123 int64_t fl
= bp
->b_flags
;
1125 * No need to wait until the buffer is unpinned.
1126 * We aren't flushing it.
1128 * chunkhold expects B_DONE to be set, whether
1129 * we actually finish the I/O or not. We don't want to
1130 * change that interface.
1135 bp
->b_iodone
= NULL
;
1136 if (!(fl
& XBF_ASYNC
)) {
1138 * Mark b_error and B_ERROR _both_.
1139 * Lot's of chunkcache code assumes that.
1140 * There's no reason to mark error for
1143 xfs_buf_ioerror(bp
, EIO
);
1144 complete(&bp
->b_iowait
);
1156 if (XFS_FORCED_SHUTDOWN(bp
->b_target
->bt_mount
)) {
1157 trace_xfs_bdstrat_shut(bp
, _RET_IP_
);
1159 * Metadata write that didn't get logged but
1160 * written delayed anyway. These aren't associated
1161 * with a transaction, and can be ignored.
1163 if (!bp
->b_iodone
&& !XFS_BUF_ISREAD(bp
))
1164 return xfs_bioerror_relse(bp
);
1166 return xfs_bioerror(bp
);
1169 xfs_buf_iorequest(bp
);
1179 ASSERT(xfs_buf_islocked(bp
));
1181 bp
->b_flags
|= XBF_WRITE
;
1182 bp
->b_flags
&= ~(XBF_ASYNC
| XBF_READ
| _XBF_DELWRI_Q
);
1186 error
= xfs_buf_iowait(bp
);
1188 xfs_force_shutdown(bp
->b_target
->bt_mount
,
1189 SHUTDOWN_META_IO_ERROR
);
1195 * Wrapper around bdstrat so that we can stop data from going to disk in case
1196 * we are shutting down the filesystem. Typically user data goes thru this
1197 * path; one of the exceptions is the superblock.
1201 struct xfs_mount
*mp
,
1204 if (XFS_FORCED_SHUTDOWN(mp
)) {
1205 trace_xfs_bdstrat_shut(bp
, _RET_IP_
);
1206 xfs_bioerror_relse(bp
);
1210 xfs_buf_iorequest(bp
);
1218 if (atomic_dec_and_test(&bp
->b_io_remaining
) == 1)
1219 xfs_buf_ioend(bp
, schedule
);
1227 xfs_buf_t
*bp
= (xfs_buf_t
*)bio
->bi_private
;
1230 * don't overwrite existing errors - otherwise we can lose errors on
1231 * buffers that require multiple bios to complete.
1234 xfs_buf_ioerror(bp
, -error
);
1236 if (!bp
->b_error
&& xfs_buf_is_vmapped(bp
) && (bp
->b_flags
& XBF_READ
))
1237 invalidate_kernel_vmap_range(bp
->b_addr
, xfs_buf_vmap_len(bp
));
1239 _xfs_buf_ioend(bp
, 1);
1244 xfs_buf_ioapply_map(
1252 int total_nr_pages
= bp
->b_page_count
;
1255 sector_t sector
= bp
->b_maps
[map
].bm_bn
;
1259 total_nr_pages
= bp
->b_page_count
;
1261 /* skip the pages in the buffer before the start offset */
1263 offset
= *buf_offset
;
1264 while (offset
>= PAGE_SIZE
) {
1266 offset
-= PAGE_SIZE
;
1270 * Limit the IO size to the length of the current vector, and update the
1271 * remaining IO count for the next time around.
1273 size
= min_t(int, BBTOB(bp
->b_maps
[map
].bm_len
), *count
);
1275 *buf_offset
+= size
;
1278 atomic_inc(&bp
->b_io_remaining
);
1279 nr_pages
= BIO_MAX_SECTORS
>> (PAGE_SHIFT
- BBSHIFT
);
1280 if (nr_pages
> total_nr_pages
)
1281 nr_pages
= total_nr_pages
;
1283 bio
= bio_alloc(GFP_NOIO
, nr_pages
);
1284 bio
->bi_bdev
= bp
->b_target
->bt_bdev
;
1285 bio
->bi_sector
= sector
;
1286 bio
->bi_end_io
= xfs_buf_bio_end_io
;
1287 bio
->bi_private
= bp
;
1290 for (; size
&& nr_pages
; nr_pages
--, page_index
++) {
1291 int rbytes
, nbytes
= PAGE_SIZE
- offset
;
1296 rbytes
= bio_add_page(bio
, bp
->b_pages
[page_index
], nbytes
,
1298 if (rbytes
< nbytes
)
1302 sector
+= BTOBB(nbytes
);
1307 if (likely(bio
->bi_size
)) {
1308 if (xfs_buf_is_vmapped(bp
)) {
1309 flush_kernel_vmap_range(bp
->b_addr
,
1310 xfs_buf_vmap_len(bp
));
1312 submit_bio(rw
, bio
);
1317 * This is guaranteed not to be the last io reference count
1318 * because the caller (xfs_buf_iorequest) holds a count itself.
1320 atomic_dec(&bp
->b_io_remaining
);
1321 xfs_buf_ioerror(bp
, EIO
);
1331 struct blk_plug plug
;
1337 if (bp
->b_flags
& XBF_WRITE
) {
1338 if (bp
->b_flags
& XBF_SYNCIO
)
1342 if (bp
->b_flags
& XBF_FUA
)
1344 if (bp
->b_flags
& XBF_FLUSH
)
1348 * Run the write verifier callback function if it exists. If
1349 * this function fails it will mark the buffer with an error and
1350 * the IO should not be dispatched.
1353 bp
->b_ops
->verify_write(bp
);
1355 xfs_force_shutdown(bp
->b_target
->bt_mount
,
1356 SHUTDOWN_CORRUPT_INCORE
);
1360 } else if (bp
->b_flags
& XBF_READ_AHEAD
) {
1366 /* we only use the buffer cache for meta-data */
1370 * Walk all the vectors issuing IO on them. Set up the initial offset
1371 * into the buffer and the desired IO size before we start -
1372 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1375 offset
= bp
->b_offset
;
1376 size
= BBTOB(bp
->b_io_length
);
1377 blk_start_plug(&plug
);
1378 for (i
= 0; i
< bp
->b_map_count
; i
++) {
1379 xfs_buf_ioapply_map(bp
, i
, &offset
, &size
, rw
);
1383 break; /* all done */
1385 blk_finish_plug(&plug
);
1392 trace_xfs_buf_iorequest(bp
, _RET_IP_
);
1394 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
1396 if (bp
->b_flags
& XBF_WRITE
)
1397 xfs_buf_wait_unpin(bp
);
1400 /* Set the count to 1 initially, this will stop an I/O
1401 * completion callout which happens before we have started
1402 * all the I/O from calling xfs_buf_ioend too early.
1404 atomic_set(&bp
->b_io_remaining
, 1);
1405 _xfs_buf_ioapply(bp
);
1406 _xfs_buf_ioend(bp
, 1);
1412 * Waits for I/O to complete on the buffer supplied. It returns immediately if
1413 * no I/O is pending or there is already a pending error on the buffer. It
1414 * returns the I/O error code, if any, or 0 if there was no error.
1420 trace_xfs_buf_iowait(bp
, _RET_IP_
);
1423 wait_for_completion(&bp
->b_iowait
);
1425 trace_xfs_buf_iowait_done(bp
, _RET_IP_
);
1437 return bp
->b_addr
+ offset
;
1439 offset
+= bp
->b_offset
;
1440 page
= bp
->b_pages
[offset
>> PAGE_SHIFT
];
1441 return (xfs_caddr_t
)page_address(page
) + (offset
& (PAGE_SIZE
-1));
1445 * Move data into or out of a buffer.
1449 xfs_buf_t
*bp
, /* buffer to process */
1450 size_t boff
, /* starting buffer offset */
1451 size_t bsize
, /* length to copy */
1452 void *data
, /* data address */
1453 xfs_buf_rw_t mode
) /* read/write/zero flag */
1457 bend
= boff
+ bsize
;
1458 while (boff
< bend
) {
1460 int page_index
, page_offset
, csize
;
1462 page_index
= (boff
+ bp
->b_offset
) >> PAGE_SHIFT
;
1463 page_offset
= (boff
+ bp
->b_offset
) & ~PAGE_MASK
;
1464 page
= bp
->b_pages
[page_index
];
1465 csize
= min_t(size_t, PAGE_SIZE
- page_offset
,
1466 BBTOB(bp
->b_io_length
) - boff
);
1468 ASSERT((csize
+ page_offset
) <= PAGE_SIZE
);
1472 memset(page_address(page
) + page_offset
, 0, csize
);
1475 memcpy(data
, page_address(page
) + page_offset
, csize
);
1478 memcpy(page_address(page
) + page_offset
, data
, csize
);
1487 * Handling of buffer targets (buftargs).
1491 * Wait for any bufs with callbacks that have been submitted but have not yet
1492 * returned. These buffers will have an elevated hold count, so wait on those
1493 * while freeing all the buffers only held by the LRU.
1497 struct xfs_buftarg
*btp
)
1502 spin_lock(&btp
->bt_lru_lock
);
1503 while (!list_empty(&btp
->bt_lru
)) {
1504 bp
= list_first_entry(&btp
->bt_lru
, struct xfs_buf
, b_lru
);
1505 if (atomic_read(&bp
->b_hold
) > 1) {
1506 trace_xfs_buf_wait_buftarg(bp
, _RET_IP_
);
1507 list_move_tail(&bp
->b_lru
, &btp
->bt_lru
);
1508 spin_unlock(&btp
->bt_lru_lock
);
1513 * clear the LRU reference count so the buffer doesn't get
1514 * ignored in xfs_buf_rele().
1516 atomic_set(&bp
->b_lru_ref
, 0);
1517 spin_unlock(&btp
->bt_lru_lock
);
1519 spin_lock(&btp
->bt_lru_lock
);
1521 spin_unlock(&btp
->bt_lru_lock
);
1526 struct shrinker
*shrink
,
1527 struct shrink_control
*sc
)
1529 struct xfs_buftarg
*btp
= container_of(shrink
,
1530 struct xfs_buftarg
, bt_shrinker
);
1532 int nr_to_scan
= sc
->nr_to_scan
;
1536 return btp
->bt_lru_nr
;
1538 spin_lock(&btp
->bt_lru_lock
);
1539 while (!list_empty(&btp
->bt_lru
)) {
1540 if (nr_to_scan
-- <= 0)
1543 bp
= list_first_entry(&btp
->bt_lru
, struct xfs_buf
, b_lru
);
1546 * Decrement the b_lru_ref count unless the value is already
1547 * zero. If the value is already zero, we need to reclaim the
1548 * buffer, otherwise it gets another trip through the LRU.
1550 if (!atomic_add_unless(&bp
->b_lru_ref
, -1, 0)) {
1551 list_move_tail(&bp
->b_lru
, &btp
->bt_lru
);
1556 * remove the buffer from the LRU now to avoid needing another
1557 * lock round trip inside xfs_buf_rele().
1559 list_move(&bp
->b_lru
, &dispose
);
1561 bp
->b_lru_flags
|= _XBF_LRU_DISPOSE
;
1563 spin_unlock(&btp
->bt_lru_lock
);
1565 while (!list_empty(&dispose
)) {
1566 bp
= list_first_entry(&dispose
, struct xfs_buf
, b_lru
);
1567 list_del_init(&bp
->b_lru
);
1571 return btp
->bt_lru_nr
;
1576 struct xfs_mount
*mp
,
1577 struct xfs_buftarg
*btp
)
1579 unregister_shrinker(&btp
->bt_shrinker
);
1581 if (mp
->m_flags
& XFS_MOUNT_BARRIER
)
1582 xfs_blkdev_issue_flush(btp
);
1588 xfs_setsize_buftarg_flags(
1590 unsigned int blocksize
,
1591 unsigned int sectorsize
,
1594 btp
->bt_bsize
= blocksize
;
1595 btp
->bt_sshift
= ffs(sectorsize
) - 1;
1596 btp
->bt_smask
= sectorsize
- 1;
1598 if (set_blocksize(btp
->bt_bdev
, sectorsize
)) {
1599 char name
[BDEVNAME_SIZE
];
1601 bdevname(btp
->bt_bdev
, name
);
1603 xfs_warn(btp
->bt_mount
,
1604 "Cannot set_blocksize to %u on device %s\n",
1613 * When allocating the initial buffer target we have not yet
1614 * read in the superblock, so don't know what sized sectors
1615 * are being used is at this early stage. Play safe.
1618 xfs_setsize_buftarg_early(
1620 struct block_device
*bdev
)
1622 return xfs_setsize_buftarg_flags(btp
,
1623 PAGE_SIZE
, bdev_logical_block_size(bdev
), 0);
1627 xfs_setsize_buftarg(
1629 unsigned int blocksize
,
1630 unsigned int sectorsize
)
1632 return xfs_setsize_buftarg_flags(btp
, blocksize
, sectorsize
, 1);
1637 struct xfs_mount
*mp
,
1638 struct block_device
*bdev
,
1644 btp
= kmem_zalloc(sizeof(*btp
), KM_SLEEP
);
1647 btp
->bt_dev
= bdev
->bd_dev
;
1648 btp
->bt_bdev
= bdev
;
1649 btp
->bt_bdi
= blk_get_backing_dev_info(bdev
);
1653 INIT_LIST_HEAD(&btp
->bt_lru
);
1654 spin_lock_init(&btp
->bt_lru_lock
);
1655 if (xfs_setsize_buftarg_early(btp
, bdev
))
1657 btp
->bt_shrinker
.shrink
= xfs_buftarg_shrink
;
1658 btp
->bt_shrinker
.seeks
= DEFAULT_SEEKS
;
1659 register_shrinker(&btp
->bt_shrinker
);
1668 * Add a buffer to the delayed write list.
1670 * This queues a buffer for writeout if it hasn't already been. Note that
1671 * neither this routine nor the buffer list submission functions perform
1672 * any internal synchronization. It is expected that the lists are thread-local
1675 * Returns true if we queued up the buffer, or false if it already had
1676 * been on the buffer list.
1679 xfs_buf_delwri_queue(
1681 struct list_head
*list
)
1683 ASSERT(xfs_buf_islocked(bp
));
1684 ASSERT(!(bp
->b_flags
& XBF_READ
));
1687 * If the buffer is already marked delwri it already is queued up
1688 * by someone else for imediate writeout. Just ignore it in that
1691 if (bp
->b_flags
& _XBF_DELWRI_Q
) {
1692 trace_xfs_buf_delwri_queued(bp
, _RET_IP_
);
1696 trace_xfs_buf_delwri_queue(bp
, _RET_IP_
);
1699 * If a buffer gets written out synchronously or marked stale while it
1700 * is on a delwri list we lazily remove it. To do this, the other party
1701 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1702 * It remains referenced and on the list. In a rare corner case it
1703 * might get readded to a delwri list after the synchronous writeout, in
1704 * which case we need just need to re-add the flag here.
1706 bp
->b_flags
|= _XBF_DELWRI_Q
;
1707 if (list_empty(&bp
->b_list
)) {
1708 atomic_inc(&bp
->b_hold
);
1709 list_add_tail(&bp
->b_list
, list
);
1716 * Compare function is more complex than it needs to be because
1717 * the return value is only 32 bits and we are doing comparisons
1723 struct list_head
*a
,
1724 struct list_head
*b
)
1726 struct xfs_buf
*ap
= container_of(a
, struct xfs_buf
, b_list
);
1727 struct xfs_buf
*bp
= container_of(b
, struct xfs_buf
, b_list
);
1730 diff
= ap
->b_maps
[0].bm_bn
- bp
->b_maps
[0].bm_bn
;
1739 __xfs_buf_delwri_submit(
1740 struct list_head
*buffer_list
,
1741 struct list_head
*io_list
,
1744 struct blk_plug plug
;
1745 struct xfs_buf
*bp
, *n
;
1748 list_for_each_entry_safe(bp
, n
, buffer_list
, b_list
) {
1750 if (xfs_buf_ispinned(bp
)) {
1754 if (!xfs_buf_trylock(bp
))
1761 * Someone else might have written the buffer synchronously or
1762 * marked it stale in the meantime. In that case only the
1763 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1764 * reference and remove it from the list here.
1766 if (!(bp
->b_flags
& _XBF_DELWRI_Q
)) {
1767 list_del_init(&bp
->b_list
);
1772 list_move_tail(&bp
->b_list
, io_list
);
1773 trace_xfs_buf_delwri_split(bp
, _RET_IP_
);
1776 list_sort(NULL
, io_list
, xfs_buf_cmp
);
1778 blk_start_plug(&plug
);
1779 list_for_each_entry_safe(bp
, n
, io_list
, b_list
) {
1780 bp
->b_flags
&= ~(_XBF_DELWRI_Q
| XBF_ASYNC
);
1781 bp
->b_flags
|= XBF_WRITE
;
1784 bp
->b_flags
|= XBF_ASYNC
;
1785 list_del_init(&bp
->b_list
);
1789 blk_finish_plug(&plug
);
1795 * Write out a buffer list asynchronously.
1797 * This will take the @buffer_list, write all non-locked and non-pinned buffers
1798 * out and not wait for I/O completion on any of the buffers. This interface
1799 * is only safely useable for callers that can track I/O completion by higher
1800 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
1804 xfs_buf_delwri_submit_nowait(
1805 struct list_head
*buffer_list
)
1807 LIST_HEAD (io_list
);
1808 return __xfs_buf_delwri_submit(buffer_list
, &io_list
, false);
1812 * Write out a buffer list synchronously.
1814 * This will take the @buffer_list, write all buffers out and wait for I/O
1815 * completion on all of the buffers. @buffer_list is consumed by the function,
1816 * so callers must have some other way of tracking buffers if they require such
1820 xfs_buf_delwri_submit(
1821 struct list_head
*buffer_list
)
1823 LIST_HEAD (io_list
);
1824 int error
= 0, error2
;
1827 __xfs_buf_delwri_submit(buffer_list
, &io_list
, true);
1829 /* Wait for IO to complete. */
1830 while (!list_empty(&io_list
)) {
1831 bp
= list_first_entry(&io_list
, struct xfs_buf
, b_list
);
1833 list_del_init(&bp
->b_list
);
1834 error2
= xfs_buf_iowait(bp
);
1846 xfs_buf_zone
= kmem_zone_init_flags(sizeof(xfs_buf_t
), "xfs_buf",
1847 KM_ZONE_HWALIGN
, NULL
);
1851 xfslogd_workqueue
= alloc_workqueue("xfslogd",
1852 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 1);
1853 if (!xfslogd_workqueue
)
1854 goto out_free_buf_zone
;
1859 kmem_zone_destroy(xfs_buf_zone
);
1865 xfs_buf_terminate(void)
1867 destroy_workqueue(xfslogd_workqueue
);
1868 kmem_zone_destroy(xfs_buf_zone
);
This page took 0.070898 seconds and 5 git commands to generate.