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>
41 #include "xfs_mount.h"
42 #include "xfs_trace.h"
44 static kmem_zone_t
*xfs_buf_zone
;
45 STATIC
int xfsbufd(void *);
47 static struct workqueue_struct
*xfslogd_workqueue
;
49 #ifdef XFS_BUF_LOCK_TRACKING
50 # define XB_SET_OWNER(bp) ((bp)->b_last_holder = current->pid)
51 # define XB_CLEAR_OWNER(bp) ((bp)->b_last_holder = -1)
52 # define XB_GET_OWNER(bp) ((bp)->b_last_holder)
54 # define XB_SET_OWNER(bp) do { } while (0)
55 # define XB_CLEAR_OWNER(bp) do { } while (0)
56 # define XB_GET_OWNER(bp) do { } while (0)
59 #define xb_to_gfp(flags) \
60 ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
61 ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
63 #define xb_to_km(flags) \
64 (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
72 * Return true if the buffer is vmapped.
74 * The XBF_MAPPED flag is set if the buffer should be mapped, but the
75 * code is clever enough to know it doesn't have to map a single page,
76 * so the check has to be both for XBF_MAPPED and bp->b_page_count > 1.
78 return (bp
->b_flags
& XBF_MAPPED
) && bp
->b_page_count
> 1;
85 return (bp
->b_page_count
* PAGE_SIZE
) - bp
->b_offset
;
89 * xfs_buf_lru_add - add a buffer to the LRU.
91 * The LRU takes a new reference to the buffer so that it will only be freed
92 * once the shrinker takes the buffer off the LRU.
98 struct xfs_buftarg
*btp
= bp
->b_target
;
100 spin_lock(&btp
->bt_lru_lock
);
101 if (list_empty(&bp
->b_lru
)) {
102 atomic_inc(&bp
->b_hold
);
103 list_add_tail(&bp
->b_lru
, &btp
->bt_lru
);
106 spin_unlock(&btp
->bt_lru_lock
);
110 * xfs_buf_lru_del - remove a buffer from the LRU
112 * The unlocked check is safe here because it only occurs when there are not
113 * b_lru_ref counts left on the inode under the pag->pag_buf_lock. it is there
114 * to optimise the shrinker removing the buffer from the LRU and calling
115 * xfs_buf_free(). i.e. it removes an unnecessary round trip on the
122 struct xfs_buftarg
*btp
= bp
->b_target
;
124 if (list_empty(&bp
->b_lru
))
127 spin_lock(&btp
->bt_lru_lock
);
128 if (!list_empty(&bp
->b_lru
)) {
129 list_del_init(&bp
->b_lru
);
132 spin_unlock(&btp
->bt_lru_lock
);
136 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
137 * b_lru_ref count so that the buffer is freed immediately when the buffer
138 * reference count falls to zero. If the buffer is already on the LRU, we need
139 * to remove the reference that LRU holds on the buffer.
141 * This prevents build-up of stale buffers on the LRU.
147 bp
->b_flags
|= XBF_STALE
;
148 xfs_buf_delwri_dequeue(bp
);
149 atomic_set(&(bp
)->b_lru_ref
, 0);
150 if (!list_empty(&bp
->b_lru
)) {
151 struct xfs_buftarg
*btp
= bp
->b_target
;
153 spin_lock(&btp
->bt_lru_lock
);
154 if (!list_empty(&bp
->b_lru
)) {
155 list_del_init(&bp
->b_lru
);
157 atomic_dec(&bp
->b_hold
);
159 spin_unlock(&btp
->bt_lru_lock
);
161 ASSERT(atomic_read(&bp
->b_hold
) >= 1);
166 struct xfs_buftarg
*target
,
167 xfs_off_t range_base
,
169 xfs_buf_flags_t flags
)
173 bp
= kmem_zone_alloc(xfs_buf_zone
, xb_to_km(flags
));
178 * We don't want certain flags to appear in b_flags.
180 flags
&= ~(XBF_LOCK
|XBF_MAPPED
|XBF_DONT_BLOCK
|XBF_READ_AHEAD
);
182 memset(bp
, 0, sizeof(xfs_buf_t
));
183 atomic_set(&bp
->b_hold
, 1);
184 atomic_set(&bp
->b_lru_ref
, 1);
185 init_completion(&bp
->b_iowait
);
186 INIT_LIST_HEAD(&bp
->b_lru
);
187 INIT_LIST_HEAD(&bp
->b_list
);
188 RB_CLEAR_NODE(&bp
->b_rbnode
);
189 sema_init(&bp
->b_sema
, 0); /* held, no waiters */
191 bp
->b_target
= target
;
192 bp
->b_file_offset
= range_base
;
194 * Set buffer_length and count_desired to the same value initially.
195 * I/O routines should use count_desired, which will be the same in
196 * most cases but may be reset (e.g. XFS recovery).
198 bp
->b_buffer_length
= bp
->b_count_desired
= range_length
;
200 bp
->b_bn
= XFS_BUF_DADDR_NULL
;
201 atomic_set(&bp
->b_pin_count
, 0);
202 init_waitqueue_head(&bp
->b_waiters
);
204 XFS_STATS_INC(xb_create
);
205 trace_xfs_buf_init(bp
, _RET_IP_
);
211 * Allocate a page array capable of holding a specified number
212 * of pages, and point the page buf at it.
218 xfs_buf_flags_t flags
)
220 /* Make sure that we have a page list */
221 if (bp
->b_pages
== NULL
) {
222 bp
->b_offset
= xfs_buf_poff(bp
->b_file_offset
);
223 bp
->b_page_count
= page_count
;
224 if (page_count
<= XB_PAGES
) {
225 bp
->b_pages
= bp
->b_page_array
;
227 bp
->b_pages
= kmem_alloc(sizeof(struct page
*) *
228 page_count
, xb_to_km(flags
));
229 if (bp
->b_pages
== NULL
)
232 memset(bp
->b_pages
, 0, sizeof(struct page
*) * page_count
);
238 * Frees b_pages if it was allocated.
244 if (bp
->b_pages
!= bp
->b_page_array
) {
245 kmem_free(bp
->b_pages
);
251 * Releases the specified buffer.
253 * The modification state of any associated pages is left unchanged.
254 * The buffer most not be on any hash - use xfs_buf_rele instead for
255 * hashed and refcounted buffers
261 trace_xfs_buf_free(bp
, _RET_IP_
);
263 ASSERT(list_empty(&bp
->b_lru
));
265 if (bp
->b_flags
& _XBF_PAGES
) {
268 if (xfs_buf_is_vmapped(bp
))
269 vm_unmap_ram(bp
->b_addr
- bp
->b_offset
,
272 for (i
= 0; i
< bp
->b_page_count
; i
++) {
273 struct page
*page
= bp
->b_pages
[i
];
277 } else if (bp
->b_flags
& _XBF_KMEM
)
278 kmem_free(bp
->b_addr
);
279 _xfs_buf_free_pages(bp
);
280 kmem_zone_free(xfs_buf_zone
, bp
);
284 * Allocates all the pages for buffer in question and builds it's page list.
287 xfs_buf_allocate_memory(
291 size_t size
= bp
->b_count_desired
;
292 size_t nbytes
, offset
;
293 gfp_t gfp_mask
= xb_to_gfp(flags
);
294 unsigned short page_count
, i
;
299 * for buffers that are contained within a single page, just allocate
300 * the memory from the heap - there's no need for the complexity of
301 * page arrays to keep allocation down to order 0.
303 if (bp
->b_buffer_length
< PAGE_SIZE
) {
304 bp
->b_addr
= kmem_alloc(bp
->b_buffer_length
, xb_to_km(flags
));
306 /* low memory - use alloc_page loop instead */
310 if (((unsigned long)(bp
->b_addr
+ bp
->b_buffer_length
- 1) &
312 ((unsigned long)bp
->b_addr
& PAGE_MASK
)) {
313 /* b_addr spans two pages - use alloc_page instead */
314 kmem_free(bp
->b_addr
);
318 bp
->b_offset
= offset_in_page(bp
->b_addr
);
319 bp
->b_pages
= bp
->b_page_array
;
320 bp
->b_pages
[0] = virt_to_page(bp
->b_addr
);
321 bp
->b_page_count
= 1;
322 bp
->b_flags
|= XBF_MAPPED
| _XBF_KMEM
;
327 end
= bp
->b_file_offset
+ bp
->b_buffer_length
;
328 page_count
= xfs_buf_btoc(end
) - xfs_buf_btoct(bp
->b_file_offset
);
329 error
= _xfs_buf_get_pages(bp
, page_count
, flags
);
333 offset
= bp
->b_offset
;
334 bp
->b_flags
|= _XBF_PAGES
;
336 for (i
= 0; i
< bp
->b_page_count
; i
++) {
340 page
= alloc_page(gfp_mask
);
341 if (unlikely(page
== NULL
)) {
342 if (flags
& XBF_READ_AHEAD
) {
343 bp
->b_page_count
= i
;
349 * This could deadlock.
351 * But until all the XFS lowlevel code is revamped to
352 * handle buffer allocation failures we can't do much.
354 if (!(++retries
% 100))
356 "possible memory allocation deadlock in %s (mode:0x%x)",
359 XFS_STATS_INC(xb_page_retries
);
360 congestion_wait(BLK_RW_ASYNC
, HZ
/50);
364 XFS_STATS_INC(xb_page_found
);
366 nbytes
= min_t(size_t, size
, PAGE_SIZE
- offset
);
368 bp
->b_pages
[i
] = page
;
374 for (i
= 0; i
< bp
->b_page_count
; i
++)
375 __free_page(bp
->b_pages
[i
]);
380 * Map buffer into kernel address-space if necessary.
387 ASSERT(bp
->b_flags
& _XBF_PAGES
);
388 if (bp
->b_page_count
== 1) {
389 /* A single page buffer is always mappable */
390 bp
->b_addr
= page_address(bp
->b_pages
[0]) + bp
->b_offset
;
391 bp
->b_flags
|= XBF_MAPPED
;
392 } else if (flags
& XBF_MAPPED
) {
396 bp
->b_addr
= vm_map_ram(bp
->b_pages
, bp
->b_page_count
,
401 } while (retried
++ <= 1);
405 bp
->b_addr
+= bp
->b_offset
;
406 bp
->b_flags
|= XBF_MAPPED
;
413 * Finding and Reading Buffers
417 * Look up, and creates if absent, a lockable buffer for
418 * a given range of an inode. The buffer is returned
419 * locked. No I/O is implied by this call.
423 xfs_buftarg_t
*btp
, /* block device target */
424 xfs_off_t ioff
, /* starting offset of range */
425 size_t isize
, /* length of range */
426 xfs_buf_flags_t flags
,
429 xfs_off_t range_base
;
431 struct xfs_perag
*pag
;
432 struct rb_node
**rbp
;
433 struct rb_node
*parent
;
436 range_base
= (ioff
<< BBSHIFT
);
437 range_length
= (isize
<< BBSHIFT
);
439 /* Check for IOs smaller than the sector size / not sector aligned */
440 ASSERT(!(range_length
< (1 << btp
->bt_sshift
)));
441 ASSERT(!(range_base
& (xfs_off_t
)btp
->bt_smask
));
444 pag
= xfs_perag_get(btp
->bt_mount
,
445 xfs_daddr_to_agno(btp
->bt_mount
, ioff
));
448 spin_lock(&pag
->pag_buf_lock
);
449 rbp
= &pag
->pag_buf_tree
.rb_node
;
454 bp
= rb_entry(parent
, struct xfs_buf
, b_rbnode
);
456 if (range_base
< bp
->b_file_offset
)
457 rbp
= &(*rbp
)->rb_left
;
458 else if (range_base
> bp
->b_file_offset
)
459 rbp
= &(*rbp
)->rb_right
;
462 * found a block offset match. If the range doesn't
463 * match, the only way this is allowed is if the buffer
464 * in the cache is stale and the transaction that made
465 * it stale has not yet committed. i.e. we are
466 * reallocating a busy extent. Skip this buffer and
467 * continue searching to the right for an exact match.
469 if (bp
->b_buffer_length
!= range_length
) {
470 ASSERT(bp
->b_flags
& XBF_STALE
);
471 rbp
= &(*rbp
)->rb_right
;
474 atomic_inc(&bp
->b_hold
);
481 rb_link_node(&new_bp
->b_rbnode
, parent
, rbp
);
482 rb_insert_color(&new_bp
->b_rbnode
, &pag
->pag_buf_tree
);
483 /* the buffer keeps the perag reference until it is freed */
485 spin_unlock(&pag
->pag_buf_lock
);
487 XFS_STATS_INC(xb_miss_locked
);
488 spin_unlock(&pag
->pag_buf_lock
);
494 spin_unlock(&pag
->pag_buf_lock
);
497 if (!xfs_buf_trylock(bp
)) {
498 if (flags
& XBF_TRYLOCK
) {
500 XFS_STATS_INC(xb_busy_locked
);
504 XFS_STATS_INC(xb_get_locked_waited
);
508 * if the buffer is stale, clear all the external state associated with
509 * it. We need to keep flags such as how we allocated the buffer memory
512 if (bp
->b_flags
& XBF_STALE
) {
513 ASSERT((bp
->b_flags
& _XBF_DELWRI_Q
) == 0);
514 bp
->b_flags
&= XBF_MAPPED
| _XBF_KMEM
| _XBF_PAGES
;
517 trace_xfs_buf_find(bp
, flags
, _RET_IP_
);
518 XFS_STATS_INC(xb_get_locked
);
523 * Assembles a buffer covering the specified range. The code is optimised for
524 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
525 * more hits than misses.
529 xfs_buftarg_t
*target
,/* target for buffer */
530 xfs_off_t ioff
, /* starting offset of range */
531 size_t isize
, /* length of range */
532 xfs_buf_flags_t flags
)
535 struct xfs_buf
*new_bp
;
538 bp
= _xfs_buf_find(target
, ioff
, isize
, flags
, NULL
);
542 new_bp
= xfs_buf_alloc(target
, ioff
<< BBSHIFT
, isize
<< BBSHIFT
,
544 if (unlikely(!new_bp
))
547 bp
= _xfs_buf_find(target
, ioff
, isize
, flags
, new_bp
);
549 kmem_zone_free(xfs_buf_zone
, new_bp
);
554 error
= xfs_buf_allocate_memory(bp
, flags
);
558 kmem_zone_free(xfs_buf_zone
, new_bp
);
561 * Now we have a workable buffer, fill in the block number so
562 * that we can do IO on it.
565 bp
->b_count_desired
= bp
->b_buffer_length
;
568 if (!(bp
->b_flags
& XBF_MAPPED
)) {
569 error
= _xfs_buf_map_pages(bp
, flags
);
570 if (unlikely(error
)) {
571 xfs_warn(target
->bt_mount
,
572 "%s: failed to map pages\n", __func__
);
577 XFS_STATS_INC(xb_get
);
578 trace_xfs_buf_get(bp
, flags
, _RET_IP_
);
582 if (flags
& (XBF_LOCK
| XBF_TRYLOCK
))
591 xfs_buf_flags_t flags
)
595 ASSERT(!(flags
& (XBF_DELWRI
|XBF_WRITE
)));
596 ASSERT(bp
->b_bn
!= XFS_BUF_DADDR_NULL
);
598 bp
->b_flags
&= ~(XBF_WRITE
| XBF_ASYNC
| XBF_DELWRI
| XBF_READ_AHEAD
);
599 bp
->b_flags
|= flags
& (XBF_READ
| XBF_ASYNC
| XBF_READ_AHEAD
);
601 status
= xfs_buf_iorequest(bp
);
602 if (status
|| bp
->b_error
|| (flags
& XBF_ASYNC
))
604 return xfs_buf_iowait(bp
);
609 xfs_buftarg_t
*target
,
612 xfs_buf_flags_t flags
)
618 bp
= xfs_buf_get(target
, ioff
, isize
, flags
);
620 trace_xfs_buf_read(bp
, flags
, _RET_IP_
);
622 if (!XFS_BUF_ISDONE(bp
)) {
623 XFS_STATS_INC(xb_get_read
);
624 _xfs_buf_read(bp
, flags
);
625 } else if (flags
& XBF_ASYNC
) {
627 * Read ahead call which is already satisfied,
632 /* We do not want read in the flags */
633 bp
->b_flags
&= ~XBF_READ
;
640 if (flags
& (XBF_LOCK
| XBF_TRYLOCK
))
647 * If we are not low on memory then do the readahead in a deadlock
652 xfs_buftarg_t
*target
,
656 if (bdi_read_congested(target
->bt_bdi
))
659 xfs_buf_read(target
, ioff
, isize
,
660 XBF_TRYLOCK
|XBF_ASYNC
|XBF_READ_AHEAD
|XBF_DONT_BLOCK
);
664 * Read an uncached buffer from disk. Allocates and returns a locked
665 * buffer containing the disk contents or nothing.
668 xfs_buf_read_uncached(
669 struct xfs_mount
*mp
,
670 struct xfs_buftarg
*target
,
678 bp
= xfs_buf_get_uncached(target
, length
, flags
);
682 /* set up the buffer for a read IO */
683 XFS_BUF_SET_ADDR(bp
, daddr
);
687 error
= xfs_buf_iowait(bp
);
688 if (error
|| bp
->b_error
) {
696 * Return a buffer allocated as an empty buffer and associated to external
697 * memory via xfs_buf_associate_memory() back to it's empty state.
705 _xfs_buf_free_pages(bp
);
708 bp
->b_page_count
= 0;
710 bp
->b_file_offset
= 0;
711 bp
->b_buffer_length
= bp
->b_count_desired
= len
;
712 bp
->b_bn
= XFS_BUF_DADDR_NULL
;
713 bp
->b_flags
&= ~XBF_MAPPED
;
716 static inline struct page
*
720 if ((!is_vmalloc_addr(addr
))) {
721 return virt_to_page(addr
);
723 return vmalloc_to_page(addr
);
728 xfs_buf_associate_memory(
735 unsigned long pageaddr
;
736 unsigned long offset
;
740 pageaddr
= (unsigned long)mem
& PAGE_MASK
;
741 offset
= (unsigned long)mem
- pageaddr
;
742 buflen
= PAGE_ALIGN(len
+ offset
);
743 page_count
= buflen
>> PAGE_SHIFT
;
745 /* Free any previous set of page pointers */
747 _xfs_buf_free_pages(bp
);
752 rval
= _xfs_buf_get_pages(bp
, page_count
, XBF_DONT_BLOCK
);
756 bp
->b_offset
= offset
;
758 for (i
= 0; i
< bp
->b_page_count
; i
++) {
759 bp
->b_pages
[i
] = mem_to_page((void *)pageaddr
);
760 pageaddr
+= PAGE_SIZE
;
763 bp
->b_count_desired
= len
;
764 bp
->b_buffer_length
= buflen
;
765 bp
->b_flags
|= XBF_MAPPED
;
771 xfs_buf_get_uncached(
772 struct xfs_buftarg
*target
,
776 unsigned long page_count
= PAGE_ALIGN(len
) >> PAGE_SHIFT
;
780 bp
= xfs_buf_alloc(target
, 0, len
, 0);
781 if (unlikely(bp
== NULL
))
784 error
= _xfs_buf_get_pages(bp
, page_count
, 0);
788 for (i
= 0; i
< page_count
; i
++) {
789 bp
->b_pages
[i
] = alloc_page(xb_to_gfp(flags
));
793 bp
->b_flags
|= _XBF_PAGES
;
795 error
= _xfs_buf_map_pages(bp
, XBF_MAPPED
);
796 if (unlikely(error
)) {
797 xfs_warn(target
->bt_mount
,
798 "%s: failed to map pages\n", __func__
);
802 trace_xfs_buf_get_uncached(bp
, _RET_IP_
);
807 __free_page(bp
->b_pages
[i
]);
808 _xfs_buf_free_pages(bp
);
810 kmem_zone_free(xfs_buf_zone
, bp
);
816 * Increment reference count on buffer, to hold the buffer concurrently
817 * with another thread which may release (free) the buffer asynchronously.
818 * Must hold the buffer already to call this function.
824 trace_xfs_buf_hold(bp
, _RET_IP_
);
825 atomic_inc(&bp
->b_hold
);
829 * Releases a hold on the specified buffer. If the
830 * the hold count is 1, calls xfs_buf_free.
836 struct xfs_perag
*pag
= bp
->b_pag
;
838 trace_xfs_buf_rele(bp
, _RET_IP_
);
841 ASSERT(list_empty(&bp
->b_lru
));
842 ASSERT(RB_EMPTY_NODE(&bp
->b_rbnode
));
843 if (atomic_dec_and_test(&bp
->b_hold
))
848 ASSERT(!RB_EMPTY_NODE(&bp
->b_rbnode
));
850 ASSERT(atomic_read(&bp
->b_hold
) > 0);
851 if (atomic_dec_and_lock(&bp
->b_hold
, &pag
->pag_buf_lock
)) {
852 if (!(bp
->b_flags
& XBF_STALE
) &&
853 atomic_read(&bp
->b_lru_ref
)) {
855 spin_unlock(&pag
->pag_buf_lock
);
858 ASSERT(!(bp
->b_flags
& (XBF_DELWRI
|_XBF_DELWRI_Q
)));
859 rb_erase(&bp
->b_rbnode
, &pag
->pag_buf_tree
);
860 spin_unlock(&pag
->pag_buf_lock
);
869 * Lock a buffer object, if it is not already locked.
871 * If we come across a stale, pinned, locked buffer, we know that we are
872 * being asked to lock a buffer that has been reallocated. Because it is
873 * pinned, we know that the log has not been pushed to disk and hence it
874 * will still be locked. Rather than continuing to have trylock attempts
875 * fail until someone else pushes the log, push it ourselves before
876 * returning. This means that the xfsaild will not get stuck trying
877 * to push on stale inode buffers.
885 locked
= down_trylock(&bp
->b_sema
) == 0;
888 else if (atomic_read(&bp
->b_pin_count
) && (bp
->b_flags
& XBF_STALE
))
889 xfs_log_force(bp
->b_target
->bt_mount
, 0);
891 trace_xfs_buf_trylock(bp
, _RET_IP_
);
896 * Lock a buffer object.
898 * If we come across a stale, pinned, locked buffer, we know that we
899 * are being asked to lock a buffer that has been reallocated. Because
900 * it is pinned, we know that the log has not been pushed to disk and
901 * hence it will still be locked. Rather than sleeping until someone
902 * else pushes the log, push it ourselves before trying to get the lock.
908 trace_xfs_buf_lock(bp
, _RET_IP_
);
910 if (atomic_read(&bp
->b_pin_count
) && (bp
->b_flags
& XBF_STALE
))
911 xfs_log_force(bp
->b_target
->bt_mount
, 0);
915 trace_xfs_buf_lock_done(bp
, _RET_IP_
);
919 * Releases the lock on the buffer object.
920 * If the buffer is marked delwri but is not queued, do so before we
921 * unlock the buffer as we need to set flags correctly. We also need to
922 * take a reference for the delwri queue because the unlocker is going to
923 * drop their's and they don't know we just queued it.
932 trace_xfs_buf_unlock(bp
, _RET_IP_
);
939 DECLARE_WAITQUEUE (wait
, current
);
941 if (atomic_read(&bp
->b_pin_count
) == 0)
944 add_wait_queue(&bp
->b_waiters
, &wait
);
946 set_current_state(TASK_UNINTERRUPTIBLE
);
947 if (atomic_read(&bp
->b_pin_count
) == 0)
951 remove_wait_queue(&bp
->b_waiters
, &wait
);
952 set_current_state(TASK_RUNNING
);
956 * Buffer Utility Routines
961 struct work_struct
*work
)
964 container_of(work
, xfs_buf_t
, b_iodone_work
);
967 (*(bp
->b_iodone
))(bp
);
968 else if (bp
->b_flags
& XBF_ASYNC
)
977 trace_xfs_buf_iodone(bp
, _RET_IP_
);
979 bp
->b_flags
&= ~(XBF_READ
| XBF_WRITE
| XBF_READ_AHEAD
);
980 if (bp
->b_error
== 0)
981 bp
->b_flags
|= XBF_DONE
;
983 if ((bp
->b_iodone
) || (bp
->b_flags
& XBF_ASYNC
)) {
985 INIT_WORK(&bp
->b_iodone_work
, xfs_buf_iodone_work
);
986 queue_work(xfslogd_workqueue
, &bp
->b_iodone_work
);
988 xfs_buf_iodone_work(&bp
->b_iodone_work
);
991 complete(&bp
->b_iowait
);
1000 ASSERT(error
>= 0 && error
<= 0xffff);
1001 bp
->b_error
= (unsigned short)error
;
1002 trace_xfs_buf_ioerror(bp
, error
, _RET_IP_
);
1006 xfs_buf_ioerror_alert(
1010 xfs_alert(bp
->b_target
->bt_mount
,
1011 "metadata I/O error: block 0x%llx (\"%s\") error %d buf count %zd",
1012 (__uint64_t
)XFS_BUF_ADDR(bp
), func
,
1013 bp
->b_error
, XFS_BUF_COUNT(bp
));
1022 bp
->b_flags
|= XBF_WRITE
;
1023 bp
->b_flags
&= ~(XBF_ASYNC
| XBF_READ
);
1025 xfs_buf_delwri_dequeue(bp
);
1028 error
= xfs_buf_iowait(bp
);
1030 xfs_force_shutdown(bp
->b_target
->bt_mount
,
1031 SHUTDOWN_META_IO_ERROR
);
1037 * Called when we want to stop a buffer from getting written or read.
1038 * We attach the EIO error, muck with its flags, and call xfs_buf_ioend
1039 * so that the proper iodone callbacks get called.
1045 #ifdef XFSERRORDEBUG
1046 ASSERT(XFS_BUF_ISREAD(bp
) || bp
->b_iodone
);
1050 * No need to wait until the buffer is unpinned, we aren't flushing it.
1052 xfs_buf_ioerror(bp
, EIO
);
1055 * We're calling xfs_buf_ioend, so delete XBF_DONE flag.
1061 xfs_buf_ioend(bp
, 0);
1067 * Same as xfs_bioerror, except that we are releasing the buffer
1068 * here ourselves, and avoiding the xfs_buf_ioend call.
1069 * This is meant for userdata errors; metadata bufs come with
1070 * iodone functions attached, so that we can track down errors.
1076 int64_t fl
= bp
->b_flags
;
1078 * No need to wait until the buffer is unpinned.
1079 * We aren't flushing it.
1081 * chunkhold expects B_DONE to be set, whether
1082 * we actually finish the I/O or not. We don't want to
1083 * change that interface.
1088 bp
->b_iodone
= NULL
;
1089 if (!(fl
& XBF_ASYNC
)) {
1091 * Mark b_error and B_ERROR _both_.
1092 * Lot's of chunkcache code assumes that.
1093 * There's no reason to mark error for
1096 xfs_buf_ioerror(bp
, EIO
);
1097 complete(&bp
->b_iowait
);
1107 * All xfs metadata buffers except log state machine buffers
1108 * get this attached as their b_bdstrat callback function.
1109 * This is so that we can catch a buffer
1110 * after prematurely unpinning it to forcibly shutdown the filesystem.
1116 if (XFS_FORCED_SHUTDOWN(bp
->b_target
->bt_mount
)) {
1117 trace_xfs_bdstrat_shut(bp
, _RET_IP_
);
1119 * Metadata write that didn't get logged but
1120 * written delayed anyway. These aren't associated
1121 * with a transaction, and can be ignored.
1123 if (!bp
->b_iodone
&& !XFS_BUF_ISREAD(bp
))
1124 return xfs_bioerror_relse(bp
);
1126 return xfs_bioerror(bp
);
1129 xfs_buf_iorequest(bp
);
1134 * Wrapper around bdstrat so that we can stop data from going to disk in case
1135 * we are shutting down the filesystem. Typically user data goes thru this
1136 * path; one of the exceptions is the superblock.
1140 struct xfs_mount
*mp
,
1143 if (XFS_FORCED_SHUTDOWN(mp
)) {
1144 trace_xfs_bdstrat_shut(bp
, _RET_IP_
);
1145 xfs_bioerror_relse(bp
);
1149 xfs_buf_iorequest(bp
);
1157 if (atomic_dec_and_test(&bp
->b_io_remaining
) == 1)
1158 xfs_buf_ioend(bp
, schedule
);
1166 xfs_buf_t
*bp
= (xfs_buf_t
*)bio
->bi_private
;
1168 xfs_buf_ioerror(bp
, -error
);
1170 if (!error
&& xfs_buf_is_vmapped(bp
) && (bp
->b_flags
& XBF_READ
))
1171 invalidate_kernel_vmap_range(bp
->b_addr
, xfs_buf_vmap_len(bp
));
1173 _xfs_buf_ioend(bp
, 1);
1181 int rw
, map_i
, total_nr_pages
, nr_pages
;
1183 int offset
= bp
->b_offset
;
1184 int size
= bp
->b_count_desired
;
1185 sector_t sector
= bp
->b_bn
;
1187 total_nr_pages
= bp
->b_page_count
;
1190 if (bp
->b_flags
& XBF_WRITE
) {
1191 if (bp
->b_flags
& XBF_SYNCIO
)
1195 if (bp
->b_flags
& XBF_FUA
)
1197 if (bp
->b_flags
& XBF_FLUSH
)
1199 } else if (bp
->b_flags
& XBF_READ_AHEAD
) {
1205 /* we only use the buffer cache for meta-data */
1209 atomic_inc(&bp
->b_io_remaining
);
1210 nr_pages
= BIO_MAX_SECTORS
>> (PAGE_SHIFT
- BBSHIFT
);
1211 if (nr_pages
> total_nr_pages
)
1212 nr_pages
= total_nr_pages
;
1214 bio
= bio_alloc(GFP_NOIO
, nr_pages
);
1215 bio
->bi_bdev
= bp
->b_target
->bt_bdev
;
1216 bio
->bi_sector
= sector
;
1217 bio
->bi_end_io
= xfs_buf_bio_end_io
;
1218 bio
->bi_private
= bp
;
1221 for (; size
&& nr_pages
; nr_pages
--, map_i
++) {
1222 int rbytes
, nbytes
= PAGE_SIZE
- offset
;
1227 rbytes
= bio_add_page(bio
, bp
->b_pages
[map_i
], nbytes
, offset
);
1228 if (rbytes
< nbytes
)
1232 sector
+= nbytes
>> BBSHIFT
;
1237 if (likely(bio
->bi_size
)) {
1238 if (xfs_buf_is_vmapped(bp
)) {
1239 flush_kernel_vmap_range(bp
->b_addr
,
1240 xfs_buf_vmap_len(bp
));
1242 submit_bio(rw
, bio
);
1246 xfs_buf_ioerror(bp
, EIO
);
1255 trace_xfs_buf_iorequest(bp
, _RET_IP_
);
1257 ASSERT(!(bp
->b_flags
& XBF_DELWRI
));
1259 if (bp
->b_flags
& XBF_WRITE
)
1260 xfs_buf_wait_unpin(bp
);
1263 /* Set the count to 1 initially, this will stop an I/O
1264 * completion callout which happens before we have started
1265 * all the I/O from calling xfs_buf_ioend too early.
1267 atomic_set(&bp
->b_io_remaining
, 1);
1268 _xfs_buf_ioapply(bp
);
1269 _xfs_buf_ioend(bp
, 0);
1276 * Waits for I/O to complete on the buffer supplied.
1277 * It returns immediately if no I/O is pending.
1278 * It returns the I/O error code, if any, or 0 if there was no error.
1284 trace_xfs_buf_iowait(bp
, _RET_IP_
);
1286 wait_for_completion(&bp
->b_iowait
);
1288 trace_xfs_buf_iowait_done(bp
, _RET_IP_
);
1299 if (bp
->b_flags
& XBF_MAPPED
)
1300 return bp
->b_addr
+ offset
;
1302 offset
+= bp
->b_offset
;
1303 page
= bp
->b_pages
[offset
>> PAGE_SHIFT
];
1304 return (xfs_caddr_t
)page_address(page
) + (offset
& (PAGE_SIZE
-1));
1308 * Move data into or out of a buffer.
1312 xfs_buf_t
*bp
, /* buffer to process */
1313 size_t boff
, /* starting buffer offset */
1314 size_t bsize
, /* length to copy */
1315 void *data
, /* data address */
1316 xfs_buf_rw_t mode
) /* read/write/zero flag */
1318 size_t bend
, cpoff
, csize
;
1321 bend
= boff
+ bsize
;
1322 while (boff
< bend
) {
1323 page
= bp
->b_pages
[xfs_buf_btoct(boff
+ bp
->b_offset
)];
1324 cpoff
= xfs_buf_poff(boff
+ bp
->b_offset
);
1325 csize
= min_t(size_t,
1326 PAGE_SIZE
-cpoff
, bp
->b_count_desired
-boff
);
1328 ASSERT(((csize
+ cpoff
) <= PAGE_SIZE
));
1332 memset(page_address(page
) + cpoff
, 0, csize
);
1335 memcpy(data
, page_address(page
) + cpoff
, csize
);
1338 memcpy(page_address(page
) + cpoff
, data
, csize
);
1347 * Handling of buffer targets (buftargs).
1351 * Wait for any bufs with callbacks that have been submitted but have not yet
1352 * returned. These buffers will have an elevated hold count, so wait on those
1353 * while freeing all the buffers only held by the LRU.
1357 struct xfs_buftarg
*btp
)
1362 spin_lock(&btp
->bt_lru_lock
);
1363 while (!list_empty(&btp
->bt_lru
)) {
1364 bp
= list_first_entry(&btp
->bt_lru
, struct xfs_buf
, b_lru
);
1365 if (atomic_read(&bp
->b_hold
) > 1) {
1366 spin_unlock(&btp
->bt_lru_lock
);
1371 * clear the LRU reference count so the buffer doesn't get
1372 * ignored in xfs_buf_rele().
1374 atomic_set(&bp
->b_lru_ref
, 0);
1375 spin_unlock(&btp
->bt_lru_lock
);
1377 spin_lock(&btp
->bt_lru_lock
);
1379 spin_unlock(&btp
->bt_lru_lock
);
1384 struct shrinker
*shrink
,
1385 struct shrink_control
*sc
)
1387 struct xfs_buftarg
*btp
= container_of(shrink
,
1388 struct xfs_buftarg
, bt_shrinker
);
1390 int nr_to_scan
= sc
->nr_to_scan
;
1394 return btp
->bt_lru_nr
;
1396 spin_lock(&btp
->bt_lru_lock
);
1397 while (!list_empty(&btp
->bt_lru
)) {
1398 if (nr_to_scan
-- <= 0)
1401 bp
= list_first_entry(&btp
->bt_lru
, struct xfs_buf
, b_lru
);
1404 * Decrement the b_lru_ref count unless the value is already
1405 * zero. If the value is already zero, we need to reclaim the
1406 * buffer, otherwise it gets another trip through the LRU.
1408 if (!atomic_add_unless(&bp
->b_lru_ref
, -1, 0)) {
1409 list_move_tail(&bp
->b_lru
, &btp
->bt_lru
);
1414 * remove the buffer from the LRU now to avoid needing another
1415 * lock round trip inside xfs_buf_rele().
1417 list_move(&bp
->b_lru
, &dispose
);
1420 spin_unlock(&btp
->bt_lru_lock
);
1422 while (!list_empty(&dispose
)) {
1423 bp
= list_first_entry(&dispose
, struct xfs_buf
, b_lru
);
1424 list_del_init(&bp
->b_lru
);
1428 return btp
->bt_lru_nr
;
1433 struct xfs_mount
*mp
,
1434 struct xfs_buftarg
*btp
)
1436 unregister_shrinker(&btp
->bt_shrinker
);
1438 xfs_flush_buftarg(btp
, 1);
1439 if (mp
->m_flags
& XFS_MOUNT_BARRIER
)
1440 xfs_blkdev_issue_flush(btp
);
1442 kthread_stop(btp
->bt_task
);
1447 xfs_setsize_buftarg_flags(
1449 unsigned int blocksize
,
1450 unsigned int sectorsize
,
1453 btp
->bt_bsize
= blocksize
;
1454 btp
->bt_sshift
= ffs(sectorsize
) - 1;
1455 btp
->bt_smask
= sectorsize
- 1;
1457 if (set_blocksize(btp
->bt_bdev
, sectorsize
)) {
1458 char name
[BDEVNAME_SIZE
];
1460 bdevname(btp
->bt_bdev
, name
);
1462 xfs_warn(btp
->bt_mount
,
1463 "Cannot set_blocksize to %u on device %s\n",
1472 * When allocating the initial buffer target we have not yet
1473 * read in the superblock, so don't know what sized sectors
1474 * are being used is at this early stage. Play safe.
1477 xfs_setsize_buftarg_early(
1479 struct block_device
*bdev
)
1481 return xfs_setsize_buftarg_flags(btp
,
1482 PAGE_SIZE
, bdev_logical_block_size(bdev
), 0);
1486 xfs_setsize_buftarg(
1488 unsigned int blocksize
,
1489 unsigned int sectorsize
)
1491 return xfs_setsize_buftarg_flags(btp
, blocksize
, sectorsize
, 1);
1495 xfs_alloc_delwri_queue(
1499 INIT_LIST_HEAD(&btp
->bt_delwri_queue
);
1500 spin_lock_init(&btp
->bt_delwri_lock
);
1502 btp
->bt_task
= kthread_run(xfsbufd
, btp
, "xfsbufd/%s", fsname
);
1503 if (IS_ERR(btp
->bt_task
))
1504 return PTR_ERR(btp
->bt_task
);
1510 struct xfs_mount
*mp
,
1511 struct block_device
*bdev
,
1517 btp
= kmem_zalloc(sizeof(*btp
), KM_SLEEP
);
1520 btp
->bt_dev
= bdev
->bd_dev
;
1521 btp
->bt_bdev
= bdev
;
1522 btp
->bt_bdi
= blk_get_backing_dev_info(bdev
);
1526 INIT_LIST_HEAD(&btp
->bt_lru
);
1527 spin_lock_init(&btp
->bt_lru_lock
);
1528 if (xfs_setsize_buftarg_early(btp
, bdev
))
1530 if (xfs_alloc_delwri_queue(btp
, fsname
))
1532 btp
->bt_shrinker
.shrink
= xfs_buftarg_shrink
;
1533 btp
->bt_shrinker
.seeks
= DEFAULT_SEEKS
;
1534 register_shrinker(&btp
->bt_shrinker
);
1544 * Delayed write buffer handling
1547 xfs_buf_delwri_queue(
1550 struct xfs_buftarg
*btp
= bp
->b_target
;
1552 trace_xfs_buf_delwri_queue(bp
, _RET_IP_
);
1554 ASSERT(!(bp
->b_flags
& XBF_READ
));
1556 spin_lock(&btp
->bt_delwri_lock
);
1557 if (!list_empty(&bp
->b_list
)) {
1558 /* if already in the queue, move it to the tail */
1559 ASSERT(bp
->b_flags
& _XBF_DELWRI_Q
);
1560 list_move_tail(&bp
->b_list
, &btp
->bt_delwri_queue
);
1562 /* start xfsbufd as it is about to have something to do */
1563 if (list_empty(&btp
->bt_delwri_queue
))
1564 wake_up_process(bp
->b_target
->bt_task
);
1566 atomic_inc(&bp
->b_hold
);
1567 bp
->b_flags
|= XBF_DELWRI
| _XBF_DELWRI_Q
| XBF_ASYNC
;
1568 list_add_tail(&bp
->b_list
, &btp
->bt_delwri_queue
);
1570 bp
->b_queuetime
= jiffies
;
1571 spin_unlock(&btp
->bt_delwri_lock
);
1575 xfs_buf_delwri_dequeue(
1580 spin_lock(&bp
->b_target
->bt_delwri_lock
);
1581 if ((bp
->b_flags
& XBF_DELWRI
) && !list_empty(&bp
->b_list
)) {
1582 ASSERT(bp
->b_flags
& _XBF_DELWRI_Q
);
1583 list_del_init(&bp
->b_list
);
1586 bp
->b_flags
&= ~(XBF_DELWRI
|_XBF_DELWRI_Q
);
1587 spin_unlock(&bp
->b_target
->bt_delwri_lock
);
1592 trace_xfs_buf_delwri_dequeue(bp
, _RET_IP_
);
1596 * If a delwri buffer needs to be pushed before it has aged out, then promote
1597 * it to the head of the delwri queue so that it will be flushed on the next
1598 * xfsbufd run. We do this by resetting the queuetime of the buffer to be older
1599 * than the age currently needed to flush the buffer. Hence the next time the
1600 * xfsbufd sees it is guaranteed to be considered old enough to flush.
1603 xfs_buf_delwri_promote(
1606 struct xfs_buftarg
*btp
= bp
->b_target
;
1607 long age
= xfs_buf_age_centisecs
* msecs_to_jiffies(10) + 1;
1609 ASSERT(bp
->b_flags
& XBF_DELWRI
);
1610 ASSERT(bp
->b_flags
& _XBF_DELWRI_Q
);
1613 * Check the buffer age before locking the delayed write queue as we
1614 * don't need to promote buffers that are already past the flush age.
1616 if (bp
->b_queuetime
< jiffies
- age
)
1618 bp
->b_queuetime
= jiffies
- age
;
1619 spin_lock(&btp
->bt_delwri_lock
);
1620 list_move(&bp
->b_list
, &btp
->bt_delwri_queue
);
1621 spin_unlock(&btp
->bt_delwri_lock
);
1625 * Move as many buffers as specified to the supplied list
1626 * idicating if we skipped any buffers to prevent deadlocks.
1629 xfs_buf_delwri_split(
1630 xfs_buftarg_t
*target
,
1631 struct list_head
*list
,
1638 force
= test_and_clear_bit(XBT_FORCE_FLUSH
, &target
->bt_flags
);
1639 INIT_LIST_HEAD(list
);
1640 spin_lock(&target
->bt_delwri_lock
);
1641 list_for_each_entry_safe(bp
, n
, &target
->bt_delwri_queue
, b_list
) {
1642 ASSERT(bp
->b_flags
& XBF_DELWRI
);
1644 if (!xfs_buf_ispinned(bp
) && xfs_buf_trylock(bp
)) {
1646 time_before(jiffies
, bp
->b_queuetime
+ age
)) {
1651 bp
->b_flags
&= ~(XBF_DELWRI
| _XBF_DELWRI_Q
);
1652 bp
->b_flags
|= XBF_WRITE
;
1653 list_move_tail(&bp
->b_list
, list
);
1654 trace_xfs_buf_delwri_split(bp
, _RET_IP_
);
1659 spin_unlock(&target
->bt_delwri_lock
);
1664 * Compare function is more complex than it needs to be because
1665 * the return value is only 32 bits and we are doing comparisons
1671 struct list_head
*a
,
1672 struct list_head
*b
)
1674 struct xfs_buf
*ap
= container_of(a
, struct xfs_buf
, b_list
);
1675 struct xfs_buf
*bp
= container_of(b
, struct xfs_buf
, b_list
);
1678 diff
= ap
->b_bn
- bp
->b_bn
;
1690 xfs_buftarg_t
*target
= (xfs_buftarg_t
*)data
;
1692 current
->flags
|= PF_MEMALLOC
;
1697 long age
= xfs_buf_age_centisecs
* msecs_to_jiffies(10);
1698 long tout
= xfs_buf_timer_centisecs
* msecs_to_jiffies(10);
1699 struct list_head tmp
;
1700 struct blk_plug plug
;
1702 if (unlikely(freezing(current
)))
1705 /* sleep for a long time if there is nothing to do. */
1706 if (list_empty(&target
->bt_delwri_queue
))
1707 tout
= MAX_SCHEDULE_TIMEOUT
;
1708 schedule_timeout_interruptible(tout
);
1710 xfs_buf_delwri_split(target
, &tmp
, age
);
1711 list_sort(NULL
, &tmp
, xfs_buf_cmp
);
1713 blk_start_plug(&plug
);
1714 while (!list_empty(&tmp
)) {
1716 bp
= list_first_entry(&tmp
, struct xfs_buf
, b_list
);
1717 list_del_init(&bp
->b_list
);
1720 blk_finish_plug(&plug
);
1721 } while (!kthread_should_stop());
1727 * Go through all incore buffers, and release buffers if they belong to
1728 * the given device. This is used in filesystem error handling to
1729 * preserve the consistency of its metadata.
1733 xfs_buftarg_t
*target
,
1738 LIST_HEAD(tmp_list
);
1739 LIST_HEAD(wait_list
);
1740 struct blk_plug plug
;
1742 flush_workqueue(xfslogd_workqueue
);
1744 set_bit(XBT_FORCE_FLUSH
, &target
->bt_flags
);
1745 pincount
= xfs_buf_delwri_split(target
, &tmp_list
, 0);
1748 * Dropped the delayed write list lock, now walk the temporary list.
1749 * All I/O is issued async and then if we need to wait for completion
1750 * we do that after issuing all the IO.
1752 list_sort(NULL
, &tmp_list
, xfs_buf_cmp
);
1754 blk_start_plug(&plug
);
1755 while (!list_empty(&tmp_list
)) {
1756 bp
= list_first_entry(&tmp_list
, struct xfs_buf
, b_list
);
1757 ASSERT(target
== bp
->b_target
);
1758 list_del_init(&bp
->b_list
);
1760 bp
->b_flags
&= ~XBF_ASYNC
;
1761 list_add(&bp
->b_list
, &wait_list
);
1765 blk_finish_plug(&plug
);
1768 /* Wait for IO to complete. */
1769 while (!list_empty(&wait_list
)) {
1770 bp
= list_first_entry(&wait_list
, struct xfs_buf
, b_list
);
1772 list_del_init(&bp
->b_list
);
1784 xfs_buf_zone
= kmem_zone_init_flags(sizeof(xfs_buf_t
), "xfs_buf",
1785 KM_ZONE_HWALIGN
, NULL
);
1789 xfslogd_workqueue
= alloc_workqueue("xfslogd",
1790 WQ_MEM_RECLAIM
| WQ_HIGHPRI
, 1);
1791 if (!xfslogd_workqueue
)
1792 goto out_free_buf_zone
;
1797 kmem_zone_destroy(xfs_buf_zone
);
1803 xfs_buf_terminate(void)
1805 destroy_workqueue(xfslogd_workqueue
);
1806 kmem_zone_destroy(xfs_buf_zone
);