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>
38 #include "xfs_trans_resv.h"
41 #include "xfs_mount.h"
42 #include "xfs_trace.h"
44 static kmem_zone_t
*xfs_buf_zone
;
46 static struct workqueue_struct
*xfslogd_workqueue
;
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 * xfs_buf_lru_add - add a buffer to the LRU.
86 * The LRU takes a new reference to the buffer so that it will only be freed
87 * once the shrinker takes the buffer off the LRU.
93 struct xfs_buftarg
*btp
= bp
->b_target
;
95 spin_lock(&btp
->bt_lru_lock
);
96 if (list_empty(&bp
->b_lru
)) {
97 atomic_inc(&bp
->b_hold
);
98 list_add_tail(&bp
->b_lru
, &btp
->bt_lru
);
100 bp
->b_lru_flags
&= ~_XBF_LRU_DISPOSE
;
102 spin_unlock(&btp
->bt_lru_lock
);
106 * xfs_buf_lru_del - remove a buffer from the LRU
108 * The unlocked check is safe here because it only occurs when there are not
109 * b_lru_ref counts left on the inode under the pag->pag_buf_lock. it is there
110 * to optimise the shrinker removing the buffer from the LRU and calling
111 * xfs_buf_free(). i.e. it removes an unnecessary round trip on the
118 struct xfs_buftarg
*btp
= bp
->b_target
;
120 if (list_empty(&bp
->b_lru
))
123 spin_lock(&btp
->bt_lru_lock
);
124 if (!list_empty(&bp
->b_lru
)) {
125 list_del_init(&bp
->b_lru
);
128 spin_unlock(&btp
->bt_lru_lock
);
132 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
133 * b_lru_ref count so that the buffer is freed immediately when the buffer
134 * reference count falls to zero. If the buffer is already on the LRU, we need
135 * to remove the reference that LRU holds on the buffer.
137 * This prevents build-up of stale buffers on the LRU.
143 ASSERT(xfs_buf_islocked(bp
));
145 bp
->b_flags
|= XBF_STALE
;
148 * Clear the delwri status so that a delwri queue walker will not
149 * flush this buffer to disk now that it is stale. The delwri queue has
150 * a reference to the buffer, so this is safe to do.
152 bp
->b_flags
&= ~_XBF_DELWRI_Q
;
154 atomic_set(&(bp
)->b_lru_ref
, 0);
155 if (!list_empty(&bp
->b_lru
)) {
156 struct xfs_buftarg
*btp
= bp
->b_target
;
158 spin_lock(&btp
->bt_lru_lock
);
159 if (!list_empty(&bp
->b_lru
) &&
160 !(bp
->b_lru_flags
& _XBF_LRU_DISPOSE
)) {
161 list_del_init(&bp
->b_lru
);
163 atomic_dec(&bp
->b_hold
);
165 spin_unlock(&btp
->bt_lru_lock
);
167 ASSERT(atomic_read(&bp
->b_hold
) >= 1);
175 ASSERT(bp
->b_maps
== NULL
);
176 bp
->b_map_count
= map_count
;
178 if (map_count
== 1) {
179 bp
->b_maps
= &bp
->__b_map
;
183 bp
->b_maps
= kmem_zalloc(map_count
* sizeof(struct xfs_buf_map
),
191 * Frees b_pages if it was allocated.
197 if (bp
->b_maps
!= &bp
->__b_map
) {
198 kmem_free(bp
->b_maps
);
205 struct xfs_buftarg
*target
,
206 struct xfs_buf_map
*map
,
208 xfs_buf_flags_t flags
)
214 bp
= kmem_zone_zalloc(xfs_buf_zone
, KM_NOFS
);
219 * We don't want certain flags to appear in b_flags unless they are
220 * specifically set by later operations on the buffer.
222 flags
&= ~(XBF_UNMAPPED
| XBF_TRYLOCK
| XBF_ASYNC
| XBF_READ_AHEAD
);
224 atomic_set(&bp
->b_hold
, 1);
225 atomic_set(&bp
->b_lru_ref
, 1);
226 init_completion(&bp
->b_iowait
);
227 INIT_LIST_HEAD(&bp
->b_lru
);
228 INIT_LIST_HEAD(&bp
->b_list
);
229 RB_CLEAR_NODE(&bp
->b_rbnode
);
230 sema_init(&bp
->b_sema
, 0); /* held, no waiters */
232 bp
->b_target
= target
;
236 * Set length and io_length to the same value initially.
237 * I/O routines should use io_length, which will be the same in
238 * most cases but may be reset (e.g. XFS recovery).
240 error
= xfs_buf_get_maps(bp
, nmaps
);
242 kmem_zone_free(xfs_buf_zone
, bp
);
246 bp
->b_bn
= map
[0].bm_bn
;
248 for (i
= 0; i
< nmaps
; i
++) {
249 bp
->b_maps
[i
].bm_bn
= map
[i
].bm_bn
;
250 bp
->b_maps
[i
].bm_len
= map
[i
].bm_len
;
251 bp
->b_length
+= map
[i
].bm_len
;
253 bp
->b_io_length
= bp
->b_length
;
255 atomic_set(&bp
->b_pin_count
, 0);
256 init_waitqueue_head(&bp
->b_waiters
);
258 XFS_STATS_INC(xb_create
);
259 trace_xfs_buf_init(bp
, _RET_IP_
);
265 * Allocate a page array capable of holding a specified number
266 * of pages, and point the page buf at it.
272 xfs_buf_flags_t flags
)
274 /* Make sure that we have a page list */
275 if (bp
->b_pages
== NULL
) {
276 bp
->b_page_count
= page_count
;
277 if (page_count
<= XB_PAGES
) {
278 bp
->b_pages
= bp
->b_page_array
;
280 bp
->b_pages
= kmem_alloc(sizeof(struct page
*) *
281 page_count
, KM_NOFS
);
282 if (bp
->b_pages
== NULL
)
285 memset(bp
->b_pages
, 0, sizeof(struct page
*) * page_count
);
291 * Frees b_pages if it was allocated.
297 if (bp
->b_pages
!= bp
->b_page_array
) {
298 kmem_free(bp
->b_pages
);
304 * Releases the specified buffer.
306 * The modification state of any associated pages is left unchanged.
307 * The buffer must not be on any hash - use xfs_buf_rele instead for
308 * hashed and refcounted buffers
314 trace_xfs_buf_free(bp
, _RET_IP_
);
316 ASSERT(list_empty(&bp
->b_lru
));
318 if (bp
->b_flags
& _XBF_PAGES
) {
321 if (xfs_buf_is_vmapped(bp
))
322 vm_unmap_ram(bp
->b_addr
- bp
->b_offset
,
325 for (i
= 0; i
< bp
->b_page_count
; i
++) {
326 struct page
*page
= bp
->b_pages
[i
];
330 } else if (bp
->b_flags
& _XBF_KMEM
)
331 kmem_free(bp
->b_addr
);
332 _xfs_buf_free_pages(bp
);
333 xfs_buf_free_maps(bp
);
334 kmem_zone_free(xfs_buf_zone
, bp
);
338 * Allocates all the pages for buffer in question and builds it's page list.
341 xfs_buf_allocate_memory(
346 size_t nbytes
, offset
;
347 gfp_t gfp_mask
= xb_to_gfp(flags
);
348 unsigned short page_count
, i
;
349 xfs_off_t start
, end
;
353 * for buffers that are contained within a single page, just allocate
354 * the memory from the heap - there's no need for the complexity of
355 * page arrays to keep allocation down to order 0.
357 size
= BBTOB(bp
->b_length
);
358 if (size
< PAGE_SIZE
) {
359 bp
->b_addr
= kmem_alloc(size
, KM_NOFS
);
361 /* low memory - use alloc_page loop instead */
365 if (((unsigned long)(bp
->b_addr
+ size
- 1) & PAGE_MASK
) !=
366 ((unsigned long)bp
->b_addr
& PAGE_MASK
)) {
367 /* b_addr spans two pages - use alloc_page instead */
368 kmem_free(bp
->b_addr
);
372 bp
->b_offset
= offset_in_page(bp
->b_addr
);
373 bp
->b_pages
= bp
->b_page_array
;
374 bp
->b_pages
[0] = virt_to_page(bp
->b_addr
);
375 bp
->b_page_count
= 1;
376 bp
->b_flags
|= _XBF_KMEM
;
381 start
= BBTOB(bp
->b_maps
[0].bm_bn
) >> PAGE_SHIFT
;
382 end
= (BBTOB(bp
->b_maps
[0].bm_bn
+ bp
->b_length
) + PAGE_SIZE
- 1)
384 page_count
= end
- start
;
385 error
= _xfs_buf_get_pages(bp
, page_count
, flags
);
389 offset
= bp
->b_offset
;
390 bp
->b_flags
|= _XBF_PAGES
;
392 for (i
= 0; i
< bp
->b_page_count
; i
++) {
396 page
= alloc_page(gfp_mask
);
397 if (unlikely(page
== NULL
)) {
398 if (flags
& XBF_READ_AHEAD
) {
399 bp
->b_page_count
= i
;
405 * This could deadlock.
407 * But until all the XFS lowlevel code is revamped to
408 * handle buffer allocation failures we can't do much.
410 if (!(++retries
% 100))
412 "possible memory allocation deadlock in %s (mode:0x%x)",
415 XFS_STATS_INC(xb_page_retries
);
416 congestion_wait(BLK_RW_ASYNC
, HZ
/50);
420 XFS_STATS_INC(xb_page_found
);
422 nbytes
= min_t(size_t, size
, PAGE_SIZE
- offset
);
424 bp
->b_pages
[i
] = page
;
430 for (i
= 0; i
< bp
->b_page_count
; i
++)
431 __free_page(bp
->b_pages
[i
]);
436 * Map buffer into kernel address-space if necessary.
443 ASSERT(bp
->b_flags
& _XBF_PAGES
);
444 if (bp
->b_page_count
== 1) {
445 /* A single page buffer is always mappable */
446 bp
->b_addr
= page_address(bp
->b_pages
[0]) + bp
->b_offset
;
447 } else if (flags
& XBF_UNMAPPED
) {
453 bp
->b_addr
= vm_map_ram(bp
->b_pages
, bp
->b_page_count
,
458 } while (retried
++ <= 1);
462 bp
->b_addr
+= bp
->b_offset
;
469 * Finding and Reading Buffers
473 * Look up, and creates if absent, a lockable buffer for
474 * a given range of an inode. The buffer is returned
475 * locked. No I/O is implied by this call.
479 struct xfs_buftarg
*btp
,
480 struct xfs_buf_map
*map
,
482 xfs_buf_flags_t flags
,
486 struct xfs_perag
*pag
;
487 struct rb_node
**rbp
;
488 struct rb_node
*parent
;
490 xfs_daddr_t blkno
= map
[0].bm_bn
;
495 for (i
= 0; i
< nmaps
; i
++)
496 numblks
+= map
[i
].bm_len
;
497 numbytes
= BBTOB(numblks
);
499 /* Check for IOs smaller than the sector size / not sector aligned */
500 ASSERT(!(numbytes
< (1 << btp
->bt_sshift
)));
501 ASSERT(!(BBTOB(blkno
) & (xfs_off_t
)btp
->bt_smask
));
504 * Corrupted block numbers can get through to here, unfortunately, so we
505 * have to check that the buffer falls within the filesystem bounds.
507 eofs
= XFS_FSB_TO_BB(btp
->bt_mount
, btp
->bt_mount
->m_sb
.sb_dblocks
);
510 * XXX (dgc): we should really be returning EFSCORRUPTED here,
511 * but none of the higher level infrastructure supports
512 * returning a specific error on buffer lookup failures.
514 xfs_alert(btp
->bt_mount
,
515 "%s: Block out of range: block 0x%llx, EOFS 0x%llx ",
516 __func__
, blkno
, eofs
);
522 pag
= xfs_perag_get(btp
->bt_mount
,
523 xfs_daddr_to_agno(btp
->bt_mount
, blkno
));
526 spin_lock(&pag
->pag_buf_lock
);
527 rbp
= &pag
->pag_buf_tree
.rb_node
;
532 bp
= rb_entry(parent
, struct xfs_buf
, b_rbnode
);
534 if (blkno
< bp
->b_bn
)
535 rbp
= &(*rbp
)->rb_left
;
536 else if (blkno
> bp
->b_bn
)
537 rbp
= &(*rbp
)->rb_right
;
540 * found a block number match. If the range doesn't
541 * match, the only way this is allowed is if the buffer
542 * in the cache is stale and the transaction that made
543 * it stale has not yet committed. i.e. we are
544 * reallocating a busy extent. Skip this buffer and
545 * continue searching to the right for an exact match.
547 if (bp
->b_length
!= numblks
) {
548 ASSERT(bp
->b_flags
& XBF_STALE
);
549 rbp
= &(*rbp
)->rb_right
;
552 atomic_inc(&bp
->b_hold
);
559 rb_link_node(&new_bp
->b_rbnode
, parent
, rbp
);
560 rb_insert_color(&new_bp
->b_rbnode
, &pag
->pag_buf_tree
);
561 /* the buffer keeps the perag reference until it is freed */
563 spin_unlock(&pag
->pag_buf_lock
);
565 XFS_STATS_INC(xb_miss_locked
);
566 spin_unlock(&pag
->pag_buf_lock
);
572 spin_unlock(&pag
->pag_buf_lock
);
575 if (!xfs_buf_trylock(bp
)) {
576 if (flags
& XBF_TRYLOCK
) {
578 XFS_STATS_INC(xb_busy_locked
);
582 XFS_STATS_INC(xb_get_locked_waited
);
586 * if the buffer is stale, clear all the external state associated with
587 * it. We need to keep flags such as how we allocated the buffer memory
590 if (bp
->b_flags
& XBF_STALE
) {
591 ASSERT((bp
->b_flags
& _XBF_DELWRI_Q
) == 0);
592 ASSERT(bp
->b_iodone
== NULL
);
593 bp
->b_flags
&= _XBF_KMEM
| _XBF_PAGES
;
597 trace_xfs_buf_find(bp
, flags
, _RET_IP_
);
598 XFS_STATS_INC(xb_get_locked
);
603 * Assembles a buffer covering the specified range. The code is optimised for
604 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
605 * more hits than misses.
609 struct xfs_buftarg
*target
,
610 struct xfs_buf_map
*map
,
612 xfs_buf_flags_t flags
)
615 struct xfs_buf
*new_bp
;
618 bp
= _xfs_buf_find(target
, map
, nmaps
, flags
, NULL
);
622 new_bp
= _xfs_buf_alloc(target
, map
, nmaps
, flags
);
623 if (unlikely(!new_bp
))
626 error
= xfs_buf_allocate_memory(new_bp
, flags
);
628 xfs_buf_free(new_bp
);
632 bp
= _xfs_buf_find(target
, map
, nmaps
, flags
, new_bp
);
634 xfs_buf_free(new_bp
);
639 xfs_buf_free(new_bp
);
643 error
= _xfs_buf_map_pages(bp
, flags
);
644 if (unlikely(error
)) {
645 xfs_warn(target
->bt_mount
,
646 "%s: failed to map pages\n", __func__
);
652 XFS_STATS_INC(xb_get
);
653 trace_xfs_buf_get(bp
, flags
, _RET_IP_
);
660 xfs_buf_flags_t flags
)
662 ASSERT(!(flags
& XBF_WRITE
));
663 ASSERT(bp
->b_maps
[0].bm_bn
!= XFS_BUF_DADDR_NULL
);
665 bp
->b_flags
&= ~(XBF_WRITE
| XBF_ASYNC
| XBF_READ_AHEAD
);
666 bp
->b_flags
|= flags
& (XBF_READ
| XBF_ASYNC
| XBF_READ_AHEAD
);
668 xfs_buf_iorequest(bp
);
669 if (flags
& XBF_ASYNC
)
671 return xfs_buf_iowait(bp
);
676 struct xfs_buftarg
*target
,
677 struct xfs_buf_map
*map
,
679 xfs_buf_flags_t flags
,
680 const struct xfs_buf_ops
*ops
)
686 bp
= xfs_buf_get_map(target
, map
, nmaps
, flags
);
688 trace_xfs_buf_read(bp
, flags
, _RET_IP_
);
690 if (!XFS_BUF_ISDONE(bp
)) {
691 XFS_STATS_INC(xb_get_read
);
693 _xfs_buf_read(bp
, flags
);
694 } else if (flags
& XBF_ASYNC
) {
696 * Read ahead call which is already satisfied,
702 /* We do not want read in the flags */
703 bp
->b_flags
&= ~XBF_READ
;
711 * If we are not low on memory then do the readahead in a deadlock
715 xfs_buf_readahead_map(
716 struct xfs_buftarg
*target
,
717 struct xfs_buf_map
*map
,
719 const struct xfs_buf_ops
*ops
)
721 if (bdi_read_congested(target
->bt_bdi
))
724 xfs_buf_read_map(target
, map
, nmaps
,
725 XBF_TRYLOCK
|XBF_ASYNC
|XBF_READ_AHEAD
, ops
);
729 * Read an uncached buffer from disk. Allocates and returns a locked
730 * buffer containing the disk contents or nothing.
733 xfs_buf_read_uncached(
734 struct xfs_buftarg
*target
,
738 const struct xfs_buf_ops
*ops
)
742 bp
= xfs_buf_get_uncached(target
, numblks
, flags
);
746 /* set up the buffer for a read IO */
747 ASSERT(bp
->b_map_count
== 1);
749 bp
->b_maps
[0].bm_bn
= daddr
;
750 bp
->b_flags
|= XBF_READ
;
753 xfsbdstrat(target
->bt_mount
, bp
);
759 * Return a buffer allocated as an empty buffer and associated to external
760 * memory via xfs_buf_associate_memory() back to it's empty state.
768 _xfs_buf_free_pages(bp
);
771 bp
->b_page_count
= 0;
773 bp
->b_length
= numblks
;
774 bp
->b_io_length
= numblks
;
776 ASSERT(bp
->b_map_count
== 1);
777 bp
->b_bn
= XFS_BUF_DADDR_NULL
;
778 bp
->b_maps
[0].bm_bn
= XFS_BUF_DADDR_NULL
;
779 bp
->b_maps
[0].bm_len
= bp
->b_length
;
782 static inline struct page
*
786 if ((!is_vmalloc_addr(addr
))) {
787 return virt_to_page(addr
);
789 return vmalloc_to_page(addr
);
794 xfs_buf_associate_memory(
801 unsigned long pageaddr
;
802 unsigned long offset
;
806 pageaddr
= (unsigned long)mem
& PAGE_MASK
;
807 offset
= (unsigned long)mem
- pageaddr
;
808 buflen
= PAGE_ALIGN(len
+ offset
);
809 page_count
= buflen
>> PAGE_SHIFT
;
811 /* Free any previous set of page pointers */
813 _xfs_buf_free_pages(bp
);
818 rval
= _xfs_buf_get_pages(bp
, page_count
, 0);
822 bp
->b_offset
= offset
;
824 for (i
= 0; i
< bp
->b_page_count
; i
++) {
825 bp
->b_pages
[i
] = mem_to_page((void *)pageaddr
);
826 pageaddr
+= PAGE_SIZE
;
829 bp
->b_io_length
= BTOBB(len
);
830 bp
->b_length
= BTOBB(buflen
);
836 xfs_buf_get_uncached(
837 struct xfs_buftarg
*target
,
841 unsigned long page_count
;
844 DEFINE_SINGLE_BUF_MAP(map
, XFS_BUF_DADDR_NULL
, numblks
);
846 bp
= _xfs_buf_alloc(target
, &map
, 1, 0);
847 if (unlikely(bp
== NULL
))
850 page_count
= PAGE_ALIGN(numblks
<< BBSHIFT
) >> PAGE_SHIFT
;
851 error
= _xfs_buf_get_pages(bp
, page_count
, 0);
855 for (i
= 0; i
< page_count
; i
++) {
856 bp
->b_pages
[i
] = alloc_page(xb_to_gfp(flags
));
860 bp
->b_flags
|= _XBF_PAGES
;
862 error
= _xfs_buf_map_pages(bp
, 0);
863 if (unlikely(error
)) {
864 xfs_warn(target
->bt_mount
,
865 "%s: failed to map pages\n", __func__
);
869 trace_xfs_buf_get_uncached(bp
, _RET_IP_
);
874 __free_page(bp
->b_pages
[i
]);
875 _xfs_buf_free_pages(bp
);
877 xfs_buf_free_maps(bp
);
878 kmem_zone_free(xfs_buf_zone
, bp
);
884 * Increment reference count on buffer, to hold the buffer concurrently
885 * with another thread which may release (free) the buffer asynchronously.
886 * Must hold the buffer already to call this function.
892 trace_xfs_buf_hold(bp
, _RET_IP_
);
893 atomic_inc(&bp
->b_hold
);
897 * Releases a hold on the specified buffer. If the
898 * the hold count is 1, calls xfs_buf_free.
904 struct xfs_perag
*pag
= bp
->b_pag
;
906 trace_xfs_buf_rele(bp
, _RET_IP_
);
909 ASSERT(list_empty(&bp
->b_lru
));
910 ASSERT(RB_EMPTY_NODE(&bp
->b_rbnode
));
911 if (atomic_dec_and_test(&bp
->b_hold
))
916 ASSERT(!RB_EMPTY_NODE(&bp
->b_rbnode
));
918 ASSERT(atomic_read(&bp
->b_hold
) > 0);
919 if (atomic_dec_and_lock(&bp
->b_hold
, &pag
->pag_buf_lock
)) {
920 if (!(bp
->b_flags
& XBF_STALE
) &&
921 atomic_read(&bp
->b_lru_ref
)) {
923 spin_unlock(&pag
->pag_buf_lock
);
926 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
927 rb_erase(&bp
->b_rbnode
, &pag
->pag_buf_tree
);
928 spin_unlock(&pag
->pag_buf_lock
);
937 * Lock a buffer object, if it is not already locked.
939 * If we come across a stale, pinned, locked buffer, we know that we are
940 * being asked to lock a buffer that has been reallocated. Because it is
941 * pinned, we know that the log has not been pushed to disk and hence it
942 * will still be locked. Rather than continuing to have trylock attempts
943 * fail until someone else pushes the log, push it ourselves before
944 * returning. This means that the xfsaild will not get stuck trying
945 * to push on stale inode buffers.
953 locked
= down_trylock(&bp
->b_sema
) == 0;
957 trace_xfs_buf_trylock(bp
, _RET_IP_
);
962 * Lock a buffer object.
964 * If we come across a stale, pinned, locked buffer, we know that we
965 * are being asked to lock a buffer that has been reallocated. Because
966 * it is pinned, we know that the log has not been pushed to disk and
967 * hence it will still be locked. Rather than sleeping until someone
968 * else pushes the log, push it ourselves before trying to get the lock.
974 trace_xfs_buf_lock(bp
, _RET_IP_
);
976 if (atomic_read(&bp
->b_pin_count
) && (bp
->b_flags
& XBF_STALE
))
977 xfs_log_force(bp
->b_target
->bt_mount
, 0);
981 trace_xfs_buf_lock_done(bp
, _RET_IP_
);
991 trace_xfs_buf_unlock(bp
, _RET_IP_
);
998 DECLARE_WAITQUEUE (wait
, current
);
1000 if (atomic_read(&bp
->b_pin_count
) == 0)
1003 add_wait_queue(&bp
->b_waiters
, &wait
);
1005 set_current_state(TASK_UNINTERRUPTIBLE
);
1006 if (atomic_read(&bp
->b_pin_count
) == 0)
1010 remove_wait_queue(&bp
->b_waiters
, &wait
);
1011 set_current_state(TASK_RUNNING
);
1015 * Buffer Utility Routines
1019 xfs_buf_iodone_work(
1020 struct work_struct
*work
)
1022 struct xfs_buf
*bp
=
1023 container_of(work
, xfs_buf_t
, b_iodone_work
);
1024 bool read
= !!(bp
->b_flags
& XBF_READ
);
1026 bp
->b_flags
&= ~(XBF_READ
| XBF_WRITE
| XBF_READ_AHEAD
);
1028 /* only validate buffers that were read without errors */
1029 if (read
&& bp
->b_ops
&& !bp
->b_error
&& (bp
->b_flags
& XBF_DONE
))
1030 bp
->b_ops
->verify_read(bp
);
1033 (*(bp
->b_iodone
))(bp
);
1034 else if (bp
->b_flags
& XBF_ASYNC
)
1037 ASSERT(read
&& bp
->b_ops
);
1038 complete(&bp
->b_iowait
);
1047 bool read
= !!(bp
->b_flags
& XBF_READ
);
1049 trace_xfs_buf_iodone(bp
, _RET_IP_
);
1051 if (bp
->b_error
== 0)
1052 bp
->b_flags
|= XBF_DONE
;
1054 if (bp
->b_iodone
|| (read
&& bp
->b_ops
) || (bp
->b_flags
& XBF_ASYNC
)) {
1056 INIT_WORK(&bp
->b_iodone_work
, xfs_buf_iodone_work
);
1057 queue_work(xfslogd_workqueue
, &bp
->b_iodone_work
);
1059 xfs_buf_iodone_work(&bp
->b_iodone_work
);
1062 bp
->b_flags
&= ~(XBF_READ
| XBF_WRITE
| XBF_READ_AHEAD
);
1063 complete(&bp
->b_iowait
);
1072 ASSERT(error
>= 0 && error
<= 0xffff);
1073 bp
->b_error
= (unsigned short)error
;
1074 trace_xfs_buf_ioerror(bp
, error
, _RET_IP_
);
1078 xfs_buf_ioerror_alert(
1082 xfs_alert(bp
->b_target
->bt_mount
,
1083 "metadata I/O error: block 0x%llx (\"%s\") error %d numblks %d",
1084 (__uint64_t
)XFS_BUF_ADDR(bp
), func
, bp
->b_error
, bp
->b_length
);
1088 * Called when we want to stop a buffer from getting written or read.
1089 * We attach the EIO error, muck with its flags, and call xfs_buf_ioend
1090 * so that the proper iodone callbacks get called.
1096 #ifdef XFSERRORDEBUG
1097 ASSERT(XFS_BUF_ISREAD(bp
) || bp
->b_iodone
);
1101 * No need to wait until the buffer is unpinned, we aren't flushing it.
1103 xfs_buf_ioerror(bp
, EIO
);
1106 * We're calling xfs_buf_ioend, so delete XBF_DONE flag.
1112 xfs_buf_ioend(bp
, 0);
1118 * Same as xfs_bioerror, except that we are releasing the buffer
1119 * here ourselves, and avoiding the xfs_buf_ioend call.
1120 * This is meant for userdata errors; metadata bufs come with
1121 * iodone functions attached, so that we can track down errors.
1127 int64_t fl
= bp
->b_flags
;
1129 * No need to wait until the buffer is unpinned.
1130 * We aren't flushing it.
1132 * chunkhold expects B_DONE to be set, whether
1133 * we actually finish the I/O or not. We don't want to
1134 * change that interface.
1139 bp
->b_iodone
= NULL
;
1140 if (!(fl
& XBF_ASYNC
)) {
1142 * Mark b_error and B_ERROR _both_.
1143 * Lot's of chunkcache code assumes that.
1144 * There's no reason to mark error for
1147 xfs_buf_ioerror(bp
, EIO
);
1148 complete(&bp
->b_iowait
);
1160 if (XFS_FORCED_SHUTDOWN(bp
->b_target
->bt_mount
)) {
1161 trace_xfs_bdstrat_shut(bp
, _RET_IP_
);
1163 * Metadata write that didn't get logged but
1164 * written delayed anyway. These aren't associated
1165 * with a transaction, and can be ignored.
1167 if (!bp
->b_iodone
&& !XFS_BUF_ISREAD(bp
))
1168 return xfs_bioerror_relse(bp
);
1170 return xfs_bioerror(bp
);
1173 xfs_buf_iorequest(bp
);
1183 ASSERT(xfs_buf_islocked(bp
));
1185 bp
->b_flags
|= XBF_WRITE
;
1186 bp
->b_flags
&= ~(XBF_ASYNC
| XBF_READ
| _XBF_DELWRI_Q
);
1190 error
= xfs_buf_iowait(bp
);
1192 xfs_force_shutdown(bp
->b_target
->bt_mount
,
1193 SHUTDOWN_META_IO_ERROR
);
1199 * Wrapper around bdstrat so that we can stop data from going to disk in case
1200 * we are shutting down the filesystem. Typically user data goes thru this
1201 * path; one of the exceptions is the superblock.
1205 struct xfs_mount
*mp
,
1208 if (XFS_FORCED_SHUTDOWN(mp
)) {
1209 trace_xfs_bdstrat_shut(bp
, _RET_IP_
);
1210 xfs_bioerror_relse(bp
);
1214 xfs_buf_iorequest(bp
);
1222 if (atomic_dec_and_test(&bp
->b_io_remaining
) == 1)
1223 xfs_buf_ioend(bp
, schedule
);
1231 xfs_buf_t
*bp
= (xfs_buf_t
*)bio
->bi_private
;
1234 * don't overwrite existing errors - otherwise we can lose errors on
1235 * buffers that require multiple bios to complete.
1238 xfs_buf_ioerror(bp
, -error
);
1240 if (!bp
->b_error
&& xfs_buf_is_vmapped(bp
) && (bp
->b_flags
& XBF_READ
))
1241 invalidate_kernel_vmap_range(bp
->b_addr
, xfs_buf_vmap_len(bp
));
1243 _xfs_buf_ioend(bp
, 1);
1248 xfs_buf_ioapply_map(
1256 int total_nr_pages
= bp
->b_page_count
;
1259 sector_t sector
= bp
->b_maps
[map
].bm_bn
;
1263 total_nr_pages
= bp
->b_page_count
;
1265 /* skip the pages in the buffer before the start offset */
1267 offset
= *buf_offset
;
1268 while (offset
>= PAGE_SIZE
) {
1270 offset
-= PAGE_SIZE
;
1274 * Limit the IO size to the length of the current vector, and update the
1275 * remaining IO count for the next time around.
1277 size
= min_t(int, BBTOB(bp
->b_maps
[map
].bm_len
), *count
);
1279 *buf_offset
+= size
;
1282 atomic_inc(&bp
->b_io_remaining
);
1283 nr_pages
= BIO_MAX_SECTORS
>> (PAGE_SHIFT
- BBSHIFT
);
1284 if (nr_pages
> total_nr_pages
)
1285 nr_pages
= total_nr_pages
;
1287 bio
= bio_alloc(GFP_NOIO
, nr_pages
);
1288 bio
->bi_bdev
= bp
->b_target
->bt_bdev
;
1289 bio
->bi_sector
= sector
;
1290 bio
->bi_end_io
= xfs_buf_bio_end_io
;
1291 bio
->bi_private
= bp
;
1294 for (; size
&& nr_pages
; nr_pages
--, page_index
++) {
1295 int rbytes
, nbytes
= PAGE_SIZE
- offset
;
1300 rbytes
= bio_add_page(bio
, bp
->b_pages
[page_index
], nbytes
,
1302 if (rbytes
< nbytes
)
1306 sector
+= BTOBB(nbytes
);
1311 if (likely(bio
->bi_size
)) {
1312 if (xfs_buf_is_vmapped(bp
)) {
1313 flush_kernel_vmap_range(bp
->b_addr
,
1314 xfs_buf_vmap_len(bp
));
1316 submit_bio(rw
, bio
);
1321 * This is guaranteed not to be the last io reference count
1322 * because the caller (xfs_buf_iorequest) holds a count itself.
1324 atomic_dec(&bp
->b_io_remaining
);
1325 xfs_buf_ioerror(bp
, EIO
);
1335 struct blk_plug plug
;
1342 * Make sure we capture only current IO errors rather than stale errors
1343 * left over from previous use of the buffer (e.g. failed readahead).
1347 if (bp
->b_flags
& XBF_WRITE
) {
1348 if (bp
->b_flags
& XBF_SYNCIO
)
1352 if (bp
->b_flags
& XBF_FUA
)
1354 if (bp
->b_flags
& XBF_FLUSH
)
1358 * Run the write verifier callback function if it exists. If
1359 * this function fails it will mark the buffer with an error and
1360 * the IO should not be dispatched.
1363 bp
->b_ops
->verify_write(bp
);
1365 xfs_force_shutdown(bp
->b_target
->bt_mount
,
1366 SHUTDOWN_CORRUPT_INCORE
);
1370 } else if (bp
->b_flags
& XBF_READ_AHEAD
) {
1376 /* we only use the buffer cache for meta-data */
1380 * Walk all the vectors issuing IO on them. Set up the initial offset
1381 * into the buffer and the desired IO size before we start -
1382 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1385 offset
= bp
->b_offset
;
1386 size
= BBTOB(bp
->b_io_length
);
1387 blk_start_plug(&plug
);
1388 for (i
= 0; i
< bp
->b_map_count
; i
++) {
1389 xfs_buf_ioapply_map(bp
, i
, &offset
, &size
, rw
);
1393 break; /* all done */
1395 blk_finish_plug(&plug
);
1402 trace_xfs_buf_iorequest(bp
, _RET_IP_
);
1404 ASSERT(!(bp
->b_flags
& _XBF_DELWRI_Q
));
1406 if (bp
->b_flags
& XBF_WRITE
)
1407 xfs_buf_wait_unpin(bp
);
1410 /* Set the count to 1 initially, this will stop an I/O
1411 * completion callout which happens before we have started
1412 * all the I/O from calling xfs_buf_ioend too early.
1414 atomic_set(&bp
->b_io_remaining
, 1);
1415 _xfs_buf_ioapply(bp
);
1416 _xfs_buf_ioend(bp
, 1);
1422 * Waits for I/O to complete on the buffer supplied. It returns immediately if
1423 * no I/O is pending or there is already a pending error on the buffer. It
1424 * returns the I/O error code, if any, or 0 if there was no error.
1430 trace_xfs_buf_iowait(bp
, _RET_IP_
);
1433 wait_for_completion(&bp
->b_iowait
);
1435 trace_xfs_buf_iowait_done(bp
, _RET_IP_
);
1447 return bp
->b_addr
+ offset
;
1449 offset
+= bp
->b_offset
;
1450 page
= bp
->b_pages
[offset
>> PAGE_SHIFT
];
1451 return (xfs_caddr_t
)page_address(page
) + (offset
& (PAGE_SIZE
-1));
1455 * Move data into or out of a buffer.
1459 xfs_buf_t
*bp
, /* buffer to process */
1460 size_t boff
, /* starting buffer offset */
1461 size_t bsize
, /* length to copy */
1462 void *data
, /* data address */
1463 xfs_buf_rw_t mode
) /* read/write/zero flag */
1467 bend
= boff
+ bsize
;
1468 while (boff
< bend
) {
1470 int page_index
, page_offset
, csize
;
1472 page_index
= (boff
+ bp
->b_offset
) >> PAGE_SHIFT
;
1473 page_offset
= (boff
+ bp
->b_offset
) & ~PAGE_MASK
;
1474 page
= bp
->b_pages
[page_index
];
1475 csize
= min_t(size_t, PAGE_SIZE
- page_offset
,
1476 BBTOB(bp
->b_io_length
) - boff
);
1478 ASSERT((csize
+ page_offset
) <= PAGE_SIZE
);
1482 memset(page_address(page
) + page_offset
, 0, csize
);
1485 memcpy(data
, page_address(page
) + page_offset
, csize
);
1488 memcpy(page_address(page
) + page_offset
, data
, csize
);
1497 * Handling of buffer targets (buftargs).
1501 * Wait for any bufs with callbacks that have been submitted but have not yet
1502 * returned. These buffers will have an elevated hold count, so wait on those
1503 * while freeing all the buffers only held by the LRU.
1507 struct xfs_buftarg
*btp
)
1512 spin_lock(&btp
->bt_lru_lock
);
1513 while (!list_empty(&btp
->bt_lru
)) {
1514 bp
= list_first_entry(&btp
->bt_lru
, struct xfs_buf
, b_lru
);
1515 if (atomic_read(&bp
->b_hold
) > 1) {
1516 trace_xfs_buf_wait_buftarg(bp
, _RET_IP_
);
1517 list_move_tail(&bp
->b_lru
, &btp
->bt_lru
);
1518 spin_unlock(&btp
->bt_lru_lock
);
1523 * clear the LRU reference count so the buffer doesn't get
1524 * ignored in xfs_buf_rele().
1526 atomic_set(&bp
->b_lru_ref
, 0);
1527 spin_unlock(&btp
->bt_lru_lock
);
1529 spin_lock(&btp
->bt_lru_lock
);
1531 spin_unlock(&btp
->bt_lru_lock
);
1536 struct shrinker
*shrink
,
1537 struct shrink_control
*sc
)
1539 struct xfs_buftarg
*btp
= container_of(shrink
,
1540 struct xfs_buftarg
, bt_shrinker
);
1542 int nr_to_scan
= sc
->nr_to_scan
;
1546 return btp
->bt_lru_nr
;
1548 spin_lock(&btp
->bt_lru_lock
);
1549 while (!list_empty(&btp
->bt_lru
)) {
1550 if (nr_to_scan
-- <= 0)
1553 bp
= list_first_entry(&btp
->bt_lru
, struct xfs_buf
, b_lru
);
1556 * Decrement the b_lru_ref count unless the value is already
1557 * zero. If the value is already zero, we need to reclaim the
1558 * buffer, otherwise it gets another trip through the LRU.
1560 if (!atomic_add_unless(&bp
->b_lru_ref
, -1, 0)) {
1561 list_move_tail(&bp
->b_lru
, &btp
->bt_lru
);
1566 * remove the buffer from the LRU now to avoid needing another
1567 * lock round trip inside xfs_buf_rele().
1569 list_move(&bp
->b_lru
, &dispose
);
1571 bp
->b_lru_flags
|= _XBF_LRU_DISPOSE
;
1573 spin_unlock(&btp
->bt_lru_lock
);
1575 while (!list_empty(&dispose
)) {
1576 bp
= list_first_entry(&dispose
, struct xfs_buf
, b_lru
);
1577 list_del_init(&bp
->b_lru
);
1581 return btp
->bt_lru_nr
;
1586 struct xfs_mount
*mp
,
1587 struct xfs_buftarg
*btp
)
1589 unregister_shrinker(&btp
->bt_shrinker
);
1591 if (mp
->m_flags
& XFS_MOUNT_BARRIER
)
1592 xfs_blkdev_issue_flush(btp
);
1598 xfs_setsize_buftarg_flags(
1600 unsigned int blocksize
,
1601 unsigned int sectorsize
,
1604 btp
->bt_bsize
= blocksize
;
1605 btp
->bt_sshift
= ffs(sectorsize
) - 1;
1606 btp
->bt_smask
= sectorsize
- 1;
1608 if (set_blocksize(btp
->bt_bdev
, sectorsize
)) {
1609 char name
[BDEVNAME_SIZE
];
1611 bdevname(btp
->bt_bdev
, name
);
1613 xfs_warn(btp
->bt_mount
,
1614 "Cannot set_blocksize to %u on device %s\n",
1623 * When allocating the initial buffer target we have not yet
1624 * read in the superblock, so don't know what sized sectors
1625 * are being used at this early stage. Play safe.
1628 xfs_setsize_buftarg_early(
1630 struct block_device
*bdev
)
1632 return xfs_setsize_buftarg_flags(btp
,
1633 PAGE_SIZE
, bdev_logical_block_size(bdev
), 0);
1637 xfs_setsize_buftarg(
1639 unsigned int blocksize
,
1640 unsigned int sectorsize
)
1642 return xfs_setsize_buftarg_flags(btp
, blocksize
, sectorsize
, 1);
1647 struct xfs_mount
*mp
,
1648 struct block_device
*bdev
,
1654 btp
= kmem_zalloc(sizeof(*btp
), KM_SLEEP
| KM_NOFS
);
1657 btp
->bt_dev
= bdev
->bd_dev
;
1658 btp
->bt_bdev
= bdev
;
1659 btp
->bt_bdi
= blk_get_backing_dev_info(bdev
);
1663 INIT_LIST_HEAD(&btp
->bt_lru
);
1664 spin_lock_init(&btp
->bt_lru_lock
);
1665 if (xfs_setsize_buftarg_early(btp
, bdev
))
1667 btp
->bt_shrinker
.shrink
= xfs_buftarg_shrink
;
1668 btp
->bt_shrinker
.seeks
= DEFAULT_SEEKS
;
1669 register_shrinker(&btp
->bt_shrinker
);
1678 * Add a buffer to the delayed write list.
1680 * This queues a buffer for writeout if it hasn't already been. Note that
1681 * neither this routine nor the buffer list submission functions perform
1682 * any internal synchronization. It is expected that the lists are thread-local
1685 * Returns true if we queued up the buffer, or false if it already had
1686 * been on the buffer list.
1689 xfs_buf_delwri_queue(
1691 struct list_head
*list
)
1693 ASSERT(xfs_buf_islocked(bp
));
1694 ASSERT(!(bp
->b_flags
& XBF_READ
));
1697 * If the buffer is already marked delwri it already is queued up
1698 * by someone else for imediate writeout. Just ignore it in that
1701 if (bp
->b_flags
& _XBF_DELWRI_Q
) {
1702 trace_xfs_buf_delwri_queued(bp
, _RET_IP_
);
1706 trace_xfs_buf_delwri_queue(bp
, _RET_IP_
);
1709 * If a buffer gets written out synchronously or marked stale while it
1710 * is on a delwri list we lazily remove it. To do this, the other party
1711 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1712 * It remains referenced and on the list. In a rare corner case it
1713 * might get readded to a delwri list after the synchronous writeout, in
1714 * which case we need just need to re-add the flag here.
1716 bp
->b_flags
|= _XBF_DELWRI_Q
;
1717 if (list_empty(&bp
->b_list
)) {
1718 atomic_inc(&bp
->b_hold
);
1719 list_add_tail(&bp
->b_list
, list
);
1726 * Compare function is more complex than it needs to be because
1727 * the return value is only 32 bits and we are doing comparisons
1733 struct list_head
*a
,
1734 struct list_head
*b
)
1736 struct xfs_buf
*ap
= container_of(a
, struct xfs_buf
, b_list
);
1737 struct xfs_buf
*bp
= container_of(b
, struct xfs_buf
, b_list
);
1740 diff
= ap
->b_maps
[0].bm_bn
- bp
->b_maps
[0].bm_bn
;
1749 __xfs_buf_delwri_submit(
1750 struct list_head
*buffer_list
,
1751 struct list_head
*io_list
,
1754 struct blk_plug plug
;
1755 struct xfs_buf
*bp
, *n
;
1758 list_for_each_entry_safe(bp
, n
, buffer_list
, b_list
) {
1760 if (xfs_buf_ispinned(bp
)) {
1764 if (!xfs_buf_trylock(bp
))
1771 * Someone else might have written the buffer synchronously or
1772 * marked it stale in the meantime. In that case only the
1773 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1774 * reference and remove it from the list here.
1776 if (!(bp
->b_flags
& _XBF_DELWRI_Q
)) {
1777 list_del_init(&bp
->b_list
);
1782 list_move_tail(&bp
->b_list
, io_list
);
1783 trace_xfs_buf_delwri_split(bp
, _RET_IP_
);
1786 list_sort(NULL
, io_list
, xfs_buf_cmp
);
1788 blk_start_plug(&plug
);
1789 list_for_each_entry_safe(bp
, n
, io_list
, b_list
) {
1790 bp
->b_flags
&= ~(_XBF_DELWRI_Q
| XBF_ASYNC
);
1791 bp
->b_flags
|= XBF_WRITE
;
1794 bp
->b_flags
|= XBF_ASYNC
;
1795 list_del_init(&bp
->b_list
);
1799 blk_finish_plug(&plug
);
1805 * Write out a buffer list asynchronously.
1807 * This will take the @buffer_list, write all non-locked and non-pinned buffers
1808 * out and not wait for I/O completion on any of the buffers. This interface
1809 * is only safely useable for callers that can track I/O completion by higher
1810 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
1814 xfs_buf_delwri_submit_nowait(
1815 struct list_head
*buffer_list
)
1817 LIST_HEAD (io_list
);
1818 return __xfs_buf_delwri_submit(buffer_list
, &io_list
, false);
1822 * Write out a buffer list synchronously.
1824 * This will take the @buffer_list, write all buffers out and wait for I/O
1825 * completion on all of the buffers. @buffer_list is consumed by the function,
1826 * so callers must have some other way of tracking buffers if they require such
1830 xfs_buf_delwri_submit(
1831 struct list_head
*buffer_list
)
1833 LIST_HEAD (io_list
);
1834 int error
= 0, error2
;
1837 __xfs_buf_delwri_submit(buffer_list
, &io_list
, true);
1839 /* Wait for IO to complete. */
1840 while (!list_empty(&io_list
)) {
1841 bp
= list_first_entry(&io_list
, struct xfs_buf
, b_list
);
1843 list_del_init(&bp
->b_list
);
1844 error2
= xfs_buf_iowait(bp
);
1856 xfs_buf_zone
= kmem_zone_init_flags(sizeof(xfs_buf_t
), "xfs_buf",
1857 KM_ZONE_HWALIGN
, NULL
);
1861 xfslogd_workqueue
= alloc_workqueue("xfslogd",
1862 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 1);
1863 if (!xfslogd_workqueue
)
1864 goto out_free_buf_zone
;
1869 kmem_zone_destroy(xfs_buf_zone
);
1875 xfs_buf_terminate(void)
1877 destroy_workqueue(xfslogd_workqueue
);
1878 kmem_zone_destroy(xfs_buf_zone
);
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