nfs41: implement DESTROY_CLIENTID operation
[linux-btrfs-devel.git] / fs / xfs / linux-2.6 / xfs_buf.c
blobd1fe74506c4c621aa8399b758126d2f8f0875c23
1 /*
2 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
3 * All Rights Reserved.
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
18 #include "xfs.h"
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>
37 #include "xfs_sb.h"
38 #include "xfs_inum.h"
39 #include "xfs_log.h"
40 #include "xfs_ag.h"
41 #include "xfs_mount.h"
42 #include "xfs_trace.h"
44 static kmem_zone_t *xfs_buf_zone;
45 STATIC int xfsbufd(void *);
46 STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
48 static struct workqueue_struct *xfslogd_workqueue;
49 struct workqueue_struct *xfsdatad_workqueue;
50 struct workqueue_struct *xfsconvertd_workqueue;
52 #ifdef XFS_BUF_LOCK_TRACKING
53 # define XB_SET_OWNER(bp) ((bp)->b_last_holder = current->pid)
54 # define XB_CLEAR_OWNER(bp) ((bp)->b_last_holder = -1)
55 # define XB_GET_OWNER(bp) ((bp)->b_last_holder)
56 #else
57 # define XB_SET_OWNER(bp) do { } while (0)
58 # define XB_CLEAR_OWNER(bp) do { } while (0)
59 # define XB_GET_OWNER(bp) do { } while (0)
60 #endif
62 #define xb_to_gfp(flags) \
63 ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
64 ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
66 #define xb_to_km(flags) \
67 (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
69 #define xfs_buf_allocate(flags) \
70 kmem_zone_alloc(xfs_buf_zone, xb_to_km(flags))
71 #define xfs_buf_deallocate(bp) \
72 kmem_zone_free(xfs_buf_zone, (bp));
74 static inline int
75 xfs_buf_is_vmapped(
76 struct xfs_buf *bp)
79 * Return true if the buffer is vmapped.
81 * The XBF_MAPPED flag is set if the buffer should be mapped, but the
82 * code is clever enough to know it doesn't have to map a single page,
83 * so the check has to be both for XBF_MAPPED and bp->b_page_count > 1.
85 return (bp->b_flags & XBF_MAPPED) && bp->b_page_count > 1;
88 static inline int
89 xfs_buf_vmap_len(
90 struct xfs_buf *bp)
92 return (bp->b_page_count * PAGE_SIZE) - bp->b_offset;
96 * xfs_buf_lru_add - add a buffer to the LRU.
98 * The LRU takes a new reference to the buffer so that it will only be freed
99 * once the shrinker takes the buffer off the LRU.
101 STATIC void
102 xfs_buf_lru_add(
103 struct xfs_buf *bp)
105 struct xfs_buftarg *btp = bp->b_target;
107 spin_lock(&btp->bt_lru_lock);
108 if (list_empty(&bp->b_lru)) {
109 atomic_inc(&bp->b_hold);
110 list_add_tail(&bp->b_lru, &btp->bt_lru);
111 btp->bt_lru_nr++;
113 spin_unlock(&btp->bt_lru_lock);
117 * xfs_buf_lru_del - remove a buffer from the LRU
119 * The unlocked check is safe here because it only occurs when there are not
120 * b_lru_ref counts left on the inode under the pag->pag_buf_lock. it is there
121 * to optimise the shrinker removing the buffer from the LRU and calling
122 * xfs_buf_free(). i.e. it removes an unnecessary round trip on the
123 * bt_lru_lock.
125 STATIC void
126 xfs_buf_lru_del(
127 struct xfs_buf *bp)
129 struct xfs_buftarg *btp = bp->b_target;
131 if (list_empty(&bp->b_lru))
132 return;
134 spin_lock(&btp->bt_lru_lock);
135 if (!list_empty(&bp->b_lru)) {
136 list_del_init(&bp->b_lru);
137 btp->bt_lru_nr--;
139 spin_unlock(&btp->bt_lru_lock);
143 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
144 * b_lru_ref count so that the buffer is freed immediately when the buffer
145 * reference count falls to zero. If the buffer is already on the LRU, we need
146 * to remove the reference that LRU holds on the buffer.
148 * This prevents build-up of stale buffers on the LRU.
150 void
151 xfs_buf_stale(
152 struct xfs_buf *bp)
154 bp->b_flags |= XBF_STALE;
155 atomic_set(&(bp)->b_lru_ref, 0);
156 if (!list_empty(&bp->b_lru)) {
157 struct xfs_buftarg *btp = bp->b_target;
159 spin_lock(&btp->bt_lru_lock);
160 if (!list_empty(&bp->b_lru)) {
161 list_del_init(&bp->b_lru);
162 btp->bt_lru_nr--;
163 atomic_dec(&bp->b_hold);
165 spin_unlock(&btp->bt_lru_lock);
167 ASSERT(atomic_read(&bp->b_hold) >= 1);
170 STATIC void
171 _xfs_buf_initialize(
172 xfs_buf_t *bp,
173 xfs_buftarg_t *target,
174 xfs_off_t range_base,
175 size_t range_length,
176 xfs_buf_flags_t flags)
179 * We don't want certain flags to appear in b_flags.
181 flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
183 memset(bp, 0, sizeof(xfs_buf_t));
184 atomic_set(&bp->b_hold, 1);
185 atomic_set(&bp->b_lru_ref, 1);
186 init_completion(&bp->b_iowait);
187 INIT_LIST_HEAD(&bp->b_lru);
188 INIT_LIST_HEAD(&bp->b_list);
189 RB_CLEAR_NODE(&bp->b_rbnode);
190 sema_init(&bp->b_sema, 0); /* held, no waiters */
191 XB_SET_OWNER(bp);
192 bp->b_target = target;
193 bp->b_file_offset = range_base;
195 * Set buffer_length and count_desired to the same value initially.
196 * I/O routines should use count_desired, which will be the same in
197 * most cases but may be reset (e.g. XFS recovery).
199 bp->b_buffer_length = bp->b_count_desired = range_length;
200 bp->b_flags = flags;
201 bp->b_bn = XFS_BUF_DADDR_NULL;
202 atomic_set(&bp->b_pin_count, 0);
203 init_waitqueue_head(&bp->b_waiters);
205 XFS_STATS_INC(xb_create);
207 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.
214 STATIC int
215 _xfs_buf_get_pages(
216 xfs_buf_t *bp,
217 int page_count,
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;
226 } else {
227 bp->b_pages = kmem_alloc(sizeof(struct page *) *
228 page_count, xb_to_km(flags));
229 if (bp->b_pages == NULL)
230 return -ENOMEM;
232 memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
234 return 0;
238 * Frees b_pages if it was allocated.
240 STATIC void
241 _xfs_buf_free_pages(
242 xfs_buf_t *bp)
244 if (bp->b_pages != bp->b_page_array) {
245 kmem_free(bp->b_pages);
246 bp->b_pages = NULL;
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
257 void
258 xfs_buf_free(
259 xfs_buf_t *bp)
261 trace_xfs_buf_free(bp, _RET_IP_);
263 ASSERT(list_empty(&bp->b_lru));
265 if (bp->b_flags & _XBF_PAGES) {
266 uint i;
268 if (xfs_buf_is_vmapped(bp))
269 vm_unmap_ram(bp->b_addr - bp->b_offset,
270 bp->b_page_count);
272 for (i = 0; i < bp->b_page_count; i++) {
273 struct page *page = bp->b_pages[i];
275 __free_page(page);
277 } else if (bp->b_flags & _XBF_KMEM)
278 kmem_free(bp->b_addr);
279 _xfs_buf_free_pages(bp);
280 xfs_buf_deallocate(bp);
284 * Allocates all the pages for buffer in question and builds it's page list.
286 STATIC int
287 xfs_buf_allocate_memory(
288 xfs_buf_t *bp,
289 uint flags)
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;
295 xfs_off_t end;
296 int error;
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));
305 if (!bp->b_addr) {
306 /* low memory - use alloc_page loop instead */
307 goto use_alloc_page;
310 if (((unsigned long)(bp->b_addr + bp->b_buffer_length - 1) &
311 PAGE_MASK) !=
312 ((unsigned long)bp->b_addr & PAGE_MASK)) {
313 /* b_addr spans two pages - use alloc_page instead */
314 kmem_free(bp->b_addr);
315 bp->b_addr = NULL;
316 goto use_alloc_page;
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;
323 return 0;
326 use_alloc_page:
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);
330 if (unlikely(error))
331 return error;
333 offset = bp->b_offset;
334 bp->b_flags |= _XBF_PAGES;
336 for (i = 0; i < bp->b_page_count; i++) {
337 struct page *page;
338 uint retries = 0;
339 retry:
340 page = alloc_page(gfp_mask);
341 if (unlikely(page == NULL)) {
342 if (flags & XBF_READ_AHEAD) {
343 bp->b_page_count = i;
344 error = ENOMEM;
345 goto out_free_pages;
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))
355 xfs_err(NULL,
356 "possible memory allocation deadlock in %s (mode:0x%x)",
357 __func__, gfp_mask);
359 XFS_STATS_INC(xb_page_retries);
360 congestion_wait(BLK_RW_ASYNC, HZ/50);
361 goto retry;
364 XFS_STATS_INC(xb_page_found);
366 nbytes = min_t(size_t, size, PAGE_SIZE - offset);
367 size -= nbytes;
368 bp->b_pages[i] = page;
369 offset = 0;
371 return 0;
373 out_free_pages:
374 for (i = 0; i < bp->b_page_count; i++)
375 __free_page(bp->b_pages[i]);
376 return error;
380 * Map buffer into kernel address-space if necessary.
382 STATIC int
383 _xfs_buf_map_pages(
384 xfs_buf_t *bp,
385 uint flags)
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) {
393 int retried = 0;
395 do {
396 bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
397 -1, PAGE_KERNEL);
398 if (bp->b_addr)
399 break;
400 vm_unmap_aliases();
401 } while (retried++ <= 1);
403 if (!bp->b_addr)
404 return -ENOMEM;
405 bp->b_addr += bp->b_offset;
406 bp->b_flags |= XBF_MAPPED;
409 return 0;
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. If other overlapping buffers exist, they are
420 * released before the new buffer is created and locked,
421 * which may imply that this call will block until those buffers
422 * are unlocked. No I/O is implied by this call.
424 xfs_buf_t *
425 _xfs_buf_find(
426 xfs_buftarg_t *btp, /* block device target */
427 xfs_off_t ioff, /* starting offset of range */
428 size_t isize, /* length of range */
429 xfs_buf_flags_t flags,
430 xfs_buf_t *new_bp)
432 xfs_off_t range_base;
433 size_t range_length;
434 struct xfs_perag *pag;
435 struct rb_node **rbp;
436 struct rb_node *parent;
437 xfs_buf_t *bp;
439 range_base = (ioff << BBSHIFT);
440 range_length = (isize << BBSHIFT);
442 /* Check for IOs smaller than the sector size / not sector aligned */
443 ASSERT(!(range_length < (1 << btp->bt_sshift)));
444 ASSERT(!(range_base & (xfs_off_t)btp->bt_smask));
446 /* get tree root */
447 pag = xfs_perag_get(btp->bt_mount,
448 xfs_daddr_to_agno(btp->bt_mount, ioff));
450 /* walk tree */
451 spin_lock(&pag->pag_buf_lock);
452 rbp = &pag->pag_buf_tree.rb_node;
453 parent = NULL;
454 bp = NULL;
455 while (*rbp) {
456 parent = *rbp;
457 bp = rb_entry(parent, struct xfs_buf, b_rbnode);
459 if (range_base < bp->b_file_offset)
460 rbp = &(*rbp)->rb_left;
461 else if (range_base > bp->b_file_offset)
462 rbp = &(*rbp)->rb_right;
463 else {
465 * found a block offset match. If the range doesn't
466 * match, the only way this is allowed is if the buffer
467 * in the cache is stale and the transaction that made
468 * it stale has not yet committed. i.e. we are
469 * reallocating a busy extent. Skip this buffer and
470 * continue searching to the right for an exact match.
472 if (bp->b_buffer_length != range_length) {
473 ASSERT(bp->b_flags & XBF_STALE);
474 rbp = &(*rbp)->rb_right;
475 continue;
477 atomic_inc(&bp->b_hold);
478 goto found;
482 /* No match found */
483 if (new_bp) {
484 _xfs_buf_initialize(new_bp, btp, range_base,
485 range_length, flags);
486 rb_link_node(&new_bp->b_rbnode, parent, rbp);
487 rb_insert_color(&new_bp->b_rbnode, &pag->pag_buf_tree);
488 /* the buffer keeps the perag reference until it is freed */
489 new_bp->b_pag = pag;
490 spin_unlock(&pag->pag_buf_lock);
491 } else {
492 XFS_STATS_INC(xb_miss_locked);
493 spin_unlock(&pag->pag_buf_lock);
494 xfs_perag_put(pag);
496 return new_bp;
498 found:
499 spin_unlock(&pag->pag_buf_lock);
500 xfs_perag_put(pag);
502 if (!xfs_buf_trylock(bp)) {
503 if (flags & XBF_TRYLOCK) {
504 xfs_buf_rele(bp);
505 XFS_STATS_INC(xb_busy_locked);
506 return NULL;
508 xfs_buf_lock(bp);
509 XFS_STATS_INC(xb_get_locked_waited);
513 * if the buffer is stale, clear all the external state associated with
514 * it. We need to keep flags such as how we allocated the buffer memory
515 * intact here.
517 if (bp->b_flags & XBF_STALE) {
518 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
519 bp->b_flags &= XBF_MAPPED | _XBF_KMEM | _XBF_PAGES;
522 trace_xfs_buf_find(bp, flags, _RET_IP_);
523 XFS_STATS_INC(xb_get_locked);
524 return bp;
528 * Assembles a buffer covering the specified range.
529 * Storage in memory for all portions of the buffer will be allocated,
530 * although backing storage may not be.
532 xfs_buf_t *
533 xfs_buf_get(
534 xfs_buftarg_t *target,/* target for buffer */
535 xfs_off_t ioff, /* starting offset of range */
536 size_t isize, /* length of range */
537 xfs_buf_flags_t flags)
539 xfs_buf_t *bp, *new_bp;
540 int error = 0;
542 new_bp = xfs_buf_allocate(flags);
543 if (unlikely(!new_bp))
544 return NULL;
546 bp = _xfs_buf_find(target, ioff, isize, flags, new_bp);
547 if (bp == new_bp) {
548 error = xfs_buf_allocate_memory(bp, flags);
549 if (error)
550 goto no_buffer;
551 } else {
552 xfs_buf_deallocate(new_bp);
553 if (unlikely(bp == NULL))
554 return NULL;
557 if (!(bp->b_flags & XBF_MAPPED)) {
558 error = _xfs_buf_map_pages(bp, flags);
559 if (unlikely(error)) {
560 xfs_warn(target->bt_mount,
561 "%s: failed to map pages\n", __func__);
562 goto no_buffer;
566 XFS_STATS_INC(xb_get);
569 * Always fill in the block number now, the mapped cases can do
570 * their own overlay of this later.
572 bp->b_bn = ioff;
573 bp->b_count_desired = bp->b_buffer_length;
575 trace_xfs_buf_get(bp, flags, _RET_IP_);
576 return bp;
578 no_buffer:
579 if (flags & (XBF_LOCK | XBF_TRYLOCK))
580 xfs_buf_unlock(bp);
581 xfs_buf_rele(bp);
582 return NULL;
585 STATIC int
586 _xfs_buf_read(
587 xfs_buf_t *bp,
588 xfs_buf_flags_t flags)
590 int status;
592 ASSERT(!(flags & (XBF_DELWRI|XBF_WRITE)));
593 ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);
595 bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_DELWRI | XBF_READ_AHEAD);
596 bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
598 status = xfs_buf_iorequest(bp);
599 if (status || XFS_BUF_ISERROR(bp) || (flags & XBF_ASYNC))
600 return status;
601 return xfs_buf_iowait(bp);
604 xfs_buf_t *
605 xfs_buf_read(
606 xfs_buftarg_t *target,
607 xfs_off_t ioff,
608 size_t isize,
609 xfs_buf_flags_t flags)
611 xfs_buf_t *bp;
613 flags |= XBF_READ;
615 bp = xfs_buf_get(target, ioff, isize, flags);
616 if (bp) {
617 trace_xfs_buf_read(bp, flags, _RET_IP_);
619 if (!XFS_BUF_ISDONE(bp)) {
620 XFS_STATS_INC(xb_get_read);
621 _xfs_buf_read(bp, flags);
622 } else if (flags & XBF_ASYNC) {
624 * Read ahead call which is already satisfied,
625 * drop the buffer
627 goto no_buffer;
628 } else {
629 /* We do not want read in the flags */
630 bp->b_flags &= ~XBF_READ;
634 return bp;
636 no_buffer:
637 if (flags & (XBF_LOCK | XBF_TRYLOCK))
638 xfs_buf_unlock(bp);
639 xfs_buf_rele(bp);
640 return NULL;
644 * If we are not low on memory then do the readahead in a deadlock
645 * safe manner.
647 void
648 xfs_buf_readahead(
649 xfs_buftarg_t *target,
650 xfs_off_t ioff,
651 size_t isize)
653 if (bdi_read_congested(target->bt_bdi))
654 return;
656 xfs_buf_read(target, ioff, isize,
657 XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD|XBF_DONT_BLOCK);
661 * Read an uncached buffer from disk. Allocates and returns a locked
662 * buffer containing the disk contents or nothing.
664 struct xfs_buf *
665 xfs_buf_read_uncached(
666 struct xfs_mount *mp,
667 struct xfs_buftarg *target,
668 xfs_daddr_t daddr,
669 size_t length,
670 int flags)
672 xfs_buf_t *bp;
673 int error;
675 bp = xfs_buf_get_uncached(target, length, flags);
676 if (!bp)
677 return NULL;
679 /* set up the buffer for a read IO */
680 XFS_BUF_SET_ADDR(bp, daddr);
681 XFS_BUF_READ(bp);
682 XFS_BUF_BUSY(bp);
684 xfsbdstrat(mp, bp);
685 error = xfs_buf_iowait(bp);
686 if (error || bp->b_error) {
687 xfs_buf_relse(bp);
688 return NULL;
690 return bp;
693 xfs_buf_t *
694 xfs_buf_get_empty(
695 size_t len,
696 xfs_buftarg_t *target)
698 xfs_buf_t *bp;
700 bp = xfs_buf_allocate(0);
701 if (bp)
702 _xfs_buf_initialize(bp, target, 0, len, 0);
703 return bp;
707 * Return a buffer allocated as an empty buffer and associated to external
708 * memory via xfs_buf_associate_memory() back to it's empty state.
710 void
711 xfs_buf_set_empty(
712 struct xfs_buf *bp,
713 size_t len)
715 if (bp->b_pages)
716 _xfs_buf_free_pages(bp);
718 bp->b_pages = NULL;
719 bp->b_page_count = 0;
720 bp->b_addr = NULL;
721 bp->b_file_offset = 0;
722 bp->b_buffer_length = bp->b_count_desired = len;
723 bp->b_bn = XFS_BUF_DADDR_NULL;
724 bp->b_flags &= ~XBF_MAPPED;
727 static inline struct page *
728 mem_to_page(
729 void *addr)
731 if ((!is_vmalloc_addr(addr))) {
732 return virt_to_page(addr);
733 } else {
734 return vmalloc_to_page(addr);
739 xfs_buf_associate_memory(
740 xfs_buf_t *bp,
741 void *mem,
742 size_t len)
744 int rval;
745 int i = 0;
746 unsigned long pageaddr;
747 unsigned long offset;
748 size_t buflen;
749 int page_count;
751 pageaddr = (unsigned long)mem & PAGE_MASK;
752 offset = (unsigned long)mem - pageaddr;
753 buflen = PAGE_ALIGN(len + offset);
754 page_count = buflen >> PAGE_SHIFT;
756 /* Free any previous set of page pointers */
757 if (bp->b_pages)
758 _xfs_buf_free_pages(bp);
760 bp->b_pages = NULL;
761 bp->b_addr = mem;
763 rval = _xfs_buf_get_pages(bp, page_count, XBF_DONT_BLOCK);
764 if (rval)
765 return rval;
767 bp->b_offset = offset;
769 for (i = 0; i < bp->b_page_count; i++) {
770 bp->b_pages[i] = mem_to_page((void *)pageaddr);
771 pageaddr += PAGE_SIZE;
774 bp->b_count_desired = len;
775 bp->b_buffer_length = buflen;
776 bp->b_flags |= XBF_MAPPED;
778 return 0;
781 xfs_buf_t *
782 xfs_buf_get_uncached(
783 struct xfs_buftarg *target,
784 size_t len,
785 int flags)
787 unsigned long page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
788 int error, i;
789 xfs_buf_t *bp;
791 bp = xfs_buf_allocate(0);
792 if (unlikely(bp == NULL))
793 goto fail;
794 _xfs_buf_initialize(bp, target, 0, len, 0);
796 error = _xfs_buf_get_pages(bp, page_count, 0);
797 if (error)
798 goto fail_free_buf;
800 for (i = 0; i < page_count; i++) {
801 bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
802 if (!bp->b_pages[i])
803 goto fail_free_mem;
805 bp->b_flags |= _XBF_PAGES;
807 error = _xfs_buf_map_pages(bp, XBF_MAPPED);
808 if (unlikely(error)) {
809 xfs_warn(target->bt_mount,
810 "%s: failed to map pages\n", __func__);
811 goto fail_free_mem;
814 trace_xfs_buf_get_uncached(bp, _RET_IP_);
815 return bp;
817 fail_free_mem:
818 while (--i >= 0)
819 __free_page(bp->b_pages[i]);
820 _xfs_buf_free_pages(bp);
821 fail_free_buf:
822 xfs_buf_deallocate(bp);
823 fail:
824 return NULL;
828 * Increment reference count on buffer, to hold the buffer concurrently
829 * with another thread which may release (free) the buffer asynchronously.
830 * Must hold the buffer already to call this function.
832 void
833 xfs_buf_hold(
834 xfs_buf_t *bp)
836 trace_xfs_buf_hold(bp, _RET_IP_);
837 atomic_inc(&bp->b_hold);
841 * Releases a hold on the specified buffer. If the
842 * the hold count is 1, calls xfs_buf_free.
844 void
845 xfs_buf_rele(
846 xfs_buf_t *bp)
848 struct xfs_perag *pag = bp->b_pag;
850 trace_xfs_buf_rele(bp, _RET_IP_);
852 if (!pag) {
853 ASSERT(list_empty(&bp->b_lru));
854 ASSERT(RB_EMPTY_NODE(&bp->b_rbnode));
855 if (atomic_dec_and_test(&bp->b_hold))
856 xfs_buf_free(bp);
857 return;
860 ASSERT(!RB_EMPTY_NODE(&bp->b_rbnode));
862 ASSERT(atomic_read(&bp->b_hold) > 0);
863 if (atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock)) {
864 if (!(bp->b_flags & XBF_STALE) &&
865 atomic_read(&bp->b_lru_ref)) {
866 xfs_buf_lru_add(bp);
867 spin_unlock(&pag->pag_buf_lock);
868 } else {
869 xfs_buf_lru_del(bp);
870 ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)));
871 rb_erase(&bp->b_rbnode, &pag->pag_buf_tree);
872 spin_unlock(&pag->pag_buf_lock);
873 xfs_perag_put(pag);
874 xfs_buf_free(bp);
881 * Lock a buffer object, if it is not already locked.
883 * If we come across a stale, pinned, locked buffer, we know that we are
884 * being asked to lock a buffer that has been reallocated. Because it is
885 * pinned, we know that the log has not been pushed to disk and hence it
886 * will still be locked. Rather than continuing to have trylock attempts
887 * fail until someone else pushes the log, push it ourselves before
888 * returning. This means that the xfsaild will not get stuck trying
889 * to push on stale inode buffers.
892 xfs_buf_trylock(
893 struct xfs_buf *bp)
895 int locked;
897 locked = down_trylock(&bp->b_sema) == 0;
898 if (locked)
899 XB_SET_OWNER(bp);
900 else if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
901 xfs_log_force(bp->b_target->bt_mount, 0);
903 trace_xfs_buf_trylock(bp, _RET_IP_);
904 return locked;
908 * Lock a buffer object.
910 * If we come across a stale, pinned, locked buffer, we know that we
911 * are being asked to lock a buffer that has been reallocated. Because
912 * it is pinned, we know that the log has not been pushed to disk and
913 * hence it will still be locked. Rather than sleeping until someone
914 * else pushes the log, push it ourselves before trying to get the lock.
916 void
917 xfs_buf_lock(
918 struct xfs_buf *bp)
920 trace_xfs_buf_lock(bp, _RET_IP_);
922 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
923 xfs_log_force(bp->b_target->bt_mount, 0);
924 down(&bp->b_sema);
925 XB_SET_OWNER(bp);
927 trace_xfs_buf_lock_done(bp, _RET_IP_);
931 * Releases the lock on the buffer object.
932 * If the buffer is marked delwri but is not queued, do so before we
933 * unlock the buffer as we need to set flags correctly. We also need to
934 * take a reference for the delwri queue because the unlocker is going to
935 * drop their's and they don't know we just queued it.
937 void
938 xfs_buf_unlock(
939 struct xfs_buf *bp)
941 if ((bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)) == XBF_DELWRI) {
942 atomic_inc(&bp->b_hold);
943 bp->b_flags |= XBF_ASYNC;
944 xfs_buf_delwri_queue(bp, 0);
947 XB_CLEAR_OWNER(bp);
948 up(&bp->b_sema);
950 trace_xfs_buf_unlock(bp, _RET_IP_);
953 STATIC void
954 xfs_buf_wait_unpin(
955 xfs_buf_t *bp)
957 DECLARE_WAITQUEUE (wait, current);
959 if (atomic_read(&bp->b_pin_count) == 0)
960 return;
962 add_wait_queue(&bp->b_waiters, &wait);
963 for (;;) {
964 set_current_state(TASK_UNINTERRUPTIBLE);
965 if (atomic_read(&bp->b_pin_count) == 0)
966 break;
967 io_schedule();
969 remove_wait_queue(&bp->b_waiters, &wait);
970 set_current_state(TASK_RUNNING);
974 * Buffer Utility Routines
977 STATIC void
978 xfs_buf_iodone_work(
979 struct work_struct *work)
981 xfs_buf_t *bp =
982 container_of(work, xfs_buf_t, b_iodone_work);
984 if (bp->b_iodone)
985 (*(bp->b_iodone))(bp);
986 else if (bp->b_flags & XBF_ASYNC)
987 xfs_buf_relse(bp);
990 void
991 xfs_buf_ioend(
992 xfs_buf_t *bp,
993 int schedule)
995 trace_xfs_buf_iodone(bp, _RET_IP_);
997 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
998 if (bp->b_error == 0)
999 bp->b_flags |= XBF_DONE;
1001 if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
1002 if (schedule) {
1003 INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
1004 queue_work(xfslogd_workqueue, &bp->b_iodone_work);
1005 } else {
1006 xfs_buf_iodone_work(&bp->b_iodone_work);
1008 } else {
1009 complete(&bp->b_iowait);
1013 void
1014 xfs_buf_ioerror(
1015 xfs_buf_t *bp,
1016 int error)
1018 ASSERT(error >= 0 && error <= 0xffff);
1019 bp->b_error = (unsigned short)error;
1020 trace_xfs_buf_ioerror(bp, error, _RET_IP_);
1024 xfs_bwrite(
1025 struct xfs_mount *mp,
1026 struct xfs_buf *bp)
1028 int error;
1030 bp->b_flags |= XBF_WRITE;
1031 bp->b_flags &= ~(XBF_ASYNC | XBF_READ);
1033 xfs_buf_delwri_dequeue(bp);
1034 xfs_bdstrat_cb(bp);
1036 error = xfs_buf_iowait(bp);
1037 if (error)
1038 xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1039 xfs_buf_relse(bp);
1040 return error;
1043 void
1044 xfs_bdwrite(
1045 void *mp,
1046 struct xfs_buf *bp)
1048 trace_xfs_buf_bdwrite(bp, _RET_IP_);
1050 bp->b_flags &= ~XBF_READ;
1051 bp->b_flags |= (XBF_DELWRI | XBF_ASYNC);
1053 xfs_buf_delwri_queue(bp, 1);
1057 * Called when we want to stop a buffer from getting written or read.
1058 * We attach the EIO error, muck with its flags, and call xfs_buf_ioend
1059 * so that the proper iodone callbacks get called.
1061 STATIC int
1062 xfs_bioerror(
1063 xfs_buf_t *bp)
1065 #ifdef XFSERRORDEBUG
1066 ASSERT(XFS_BUF_ISREAD(bp) || bp->b_iodone);
1067 #endif
1070 * No need to wait until the buffer is unpinned, we aren't flushing it.
1072 XFS_BUF_ERROR(bp, EIO);
1075 * We're calling xfs_buf_ioend, so delete XBF_DONE flag.
1077 XFS_BUF_UNREAD(bp);
1078 XFS_BUF_UNDELAYWRITE(bp);
1079 XFS_BUF_UNDONE(bp);
1080 XFS_BUF_STALE(bp);
1082 xfs_buf_ioend(bp, 0);
1084 return EIO;
1088 * Same as xfs_bioerror, except that we are releasing the buffer
1089 * here ourselves, and avoiding the xfs_buf_ioend call.
1090 * This is meant for userdata errors; metadata bufs come with
1091 * iodone functions attached, so that we can track down errors.
1093 STATIC int
1094 xfs_bioerror_relse(
1095 struct xfs_buf *bp)
1097 int64_t fl = XFS_BUF_BFLAGS(bp);
1099 * No need to wait until the buffer is unpinned.
1100 * We aren't flushing it.
1102 * chunkhold expects B_DONE to be set, whether
1103 * we actually finish the I/O or not. We don't want to
1104 * change that interface.
1106 XFS_BUF_UNREAD(bp);
1107 XFS_BUF_UNDELAYWRITE(bp);
1108 XFS_BUF_DONE(bp);
1109 XFS_BUF_STALE(bp);
1110 bp->b_iodone = NULL;
1111 if (!(fl & XBF_ASYNC)) {
1113 * Mark b_error and B_ERROR _both_.
1114 * Lot's of chunkcache code assumes that.
1115 * There's no reason to mark error for
1116 * ASYNC buffers.
1118 XFS_BUF_ERROR(bp, EIO);
1119 XFS_BUF_FINISH_IOWAIT(bp);
1120 } else {
1121 xfs_buf_relse(bp);
1124 return EIO;
1129 * All xfs metadata buffers except log state machine buffers
1130 * get this attached as their b_bdstrat callback function.
1131 * This is so that we can catch a buffer
1132 * after prematurely unpinning it to forcibly shutdown the filesystem.
1135 xfs_bdstrat_cb(
1136 struct xfs_buf *bp)
1138 if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
1139 trace_xfs_bdstrat_shut(bp, _RET_IP_);
1141 * Metadata write that didn't get logged but
1142 * written delayed anyway. These aren't associated
1143 * with a transaction, and can be ignored.
1145 if (!bp->b_iodone && !XFS_BUF_ISREAD(bp))
1146 return xfs_bioerror_relse(bp);
1147 else
1148 return xfs_bioerror(bp);
1151 xfs_buf_iorequest(bp);
1152 return 0;
1156 * Wrapper around bdstrat so that we can stop data from going to disk in case
1157 * we are shutting down the filesystem. Typically user data goes thru this
1158 * path; one of the exceptions is the superblock.
1160 void
1161 xfsbdstrat(
1162 struct xfs_mount *mp,
1163 struct xfs_buf *bp)
1165 if (XFS_FORCED_SHUTDOWN(mp)) {
1166 trace_xfs_bdstrat_shut(bp, _RET_IP_);
1167 xfs_bioerror_relse(bp);
1168 return;
1171 xfs_buf_iorequest(bp);
1174 STATIC void
1175 _xfs_buf_ioend(
1176 xfs_buf_t *bp,
1177 int schedule)
1179 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1180 xfs_buf_ioend(bp, schedule);
1183 STATIC void
1184 xfs_buf_bio_end_io(
1185 struct bio *bio,
1186 int error)
1188 xfs_buf_t *bp = (xfs_buf_t *)bio->bi_private;
1190 xfs_buf_ioerror(bp, -error);
1192 if (!error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1193 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1195 _xfs_buf_ioend(bp, 1);
1196 bio_put(bio);
1199 STATIC void
1200 _xfs_buf_ioapply(
1201 xfs_buf_t *bp)
1203 int rw, map_i, total_nr_pages, nr_pages;
1204 struct bio *bio;
1205 int offset = bp->b_offset;
1206 int size = bp->b_count_desired;
1207 sector_t sector = bp->b_bn;
1209 total_nr_pages = bp->b_page_count;
1210 map_i = 0;
1212 if (bp->b_flags & XBF_WRITE) {
1213 if (bp->b_flags & XBF_SYNCIO)
1214 rw = WRITE_SYNC;
1215 else
1216 rw = WRITE;
1217 if (bp->b_flags & XBF_FUA)
1218 rw |= REQ_FUA;
1219 if (bp->b_flags & XBF_FLUSH)
1220 rw |= REQ_FLUSH;
1221 } else if (bp->b_flags & XBF_READ_AHEAD) {
1222 rw = READA;
1223 } else {
1224 rw = READ;
1227 /* we only use the buffer cache for meta-data */
1228 rw |= REQ_META;
1230 next_chunk:
1231 atomic_inc(&bp->b_io_remaining);
1232 nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
1233 if (nr_pages > total_nr_pages)
1234 nr_pages = total_nr_pages;
1236 bio = bio_alloc(GFP_NOIO, nr_pages);
1237 bio->bi_bdev = bp->b_target->bt_bdev;
1238 bio->bi_sector = sector;
1239 bio->bi_end_io = xfs_buf_bio_end_io;
1240 bio->bi_private = bp;
1243 for (; size && nr_pages; nr_pages--, map_i++) {
1244 int rbytes, nbytes = PAGE_SIZE - offset;
1246 if (nbytes > size)
1247 nbytes = size;
1249 rbytes = bio_add_page(bio, bp->b_pages[map_i], nbytes, offset);
1250 if (rbytes < nbytes)
1251 break;
1253 offset = 0;
1254 sector += nbytes >> BBSHIFT;
1255 size -= nbytes;
1256 total_nr_pages--;
1259 if (likely(bio->bi_size)) {
1260 if (xfs_buf_is_vmapped(bp)) {
1261 flush_kernel_vmap_range(bp->b_addr,
1262 xfs_buf_vmap_len(bp));
1264 submit_bio(rw, bio);
1265 if (size)
1266 goto next_chunk;
1267 } else {
1268 xfs_buf_ioerror(bp, EIO);
1269 bio_put(bio);
1274 xfs_buf_iorequest(
1275 xfs_buf_t *bp)
1277 trace_xfs_buf_iorequest(bp, _RET_IP_);
1279 if (bp->b_flags & XBF_DELWRI) {
1280 xfs_buf_delwri_queue(bp, 1);
1281 return 0;
1284 if (bp->b_flags & XBF_WRITE) {
1285 xfs_buf_wait_unpin(bp);
1288 xfs_buf_hold(bp);
1290 /* Set the count to 1 initially, this will stop an I/O
1291 * completion callout which happens before we have started
1292 * all the I/O from calling xfs_buf_ioend too early.
1294 atomic_set(&bp->b_io_remaining, 1);
1295 _xfs_buf_ioapply(bp);
1296 _xfs_buf_ioend(bp, 0);
1298 xfs_buf_rele(bp);
1299 return 0;
1303 * Waits for I/O to complete on the buffer supplied.
1304 * It returns immediately if no I/O is pending.
1305 * It returns the I/O error code, if any, or 0 if there was no error.
1308 xfs_buf_iowait(
1309 xfs_buf_t *bp)
1311 trace_xfs_buf_iowait(bp, _RET_IP_);
1313 wait_for_completion(&bp->b_iowait);
1315 trace_xfs_buf_iowait_done(bp, _RET_IP_);
1316 return bp->b_error;
1319 xfs_caddr_t
1320 xfs_buf_offset(
1321 xfs_buf_t *bp,
1322 size_t offset)
1324 struct page *page;
1326 if (bp->b_flags & XBF_MAPPED)
1327 return XFS_BUF_PTR(bp) + offset;
1329 offset += bp->b_offset;
1330 page = bp->b_pages[offset >> PAGE_SHIFT];
1331 return (xfs_caddr_t)page_address(page) + (offset & (PAGE_SIZE-1));
1335 * Move data into or out of a buffer.
1337 void
1338 xfs_buf_iomove(
1339 xfs_buf_t *bp, /* buffer to process */
1340 size_t boff, /* starting buffer offset */
1341 size_t bsize, /* length to copy */
1342 void *data, /* data address */
1343 xfs_buf_rw_t mode) /* read/write/zero flag */
1345 size_t bend, cpoff, csize;
1346 struct page *page;
1348 bend = boff + bsize;
1349 while (boff < bend) {
1350 page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
1351 cpoff = xfs_buf_poff(boff + bp->b_offset);
1352 csize = min_t(size_t,
1353 PAGE_SIZE-cpoff, bp->b_count_desired-boff);
1355 ASSERT(((csize + cpoff) <= PAGE_SIZE));
1357 switch (mode) {
1358 case XBRW_ZERO:
1359 memset(page_address(page) + cpoff, 0, csize);
1360 break;
1361 case XBRW_READ:
1362 memcpy(data, page_address(page) + cpoff, csize);
1363 break;
1364 case XBRW_WRITE:
1365 memcpy(page_address(page) + cpoff, data, csize);
1368 boff += csize;
1369 data += csize;
1374 * Handling of buffer targets (buftargs).
1378 * Wait for any bufs with callbacks that have been submitted but have not yet
1379 * returned. These buffers will have an elevated hold count, so wait on those
1380 * while freeing all the buffers only held by the LRU.
1382 void
1383 xfs_wait_buftarg(
1384 struct xfs_buftarg *btp)
1386 struct xfs_buf *bp;
1388 restart:
1389 spin_lock(&btp->bt_lru_lock);
1390 while (!list_empty(&btp->bt_lru)) {
1391 bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru);
1392 if (atomic_read(&bp->b_hold) > 1) {
1393 spin_unlock(&btp->bt_lru_lock);
1394 delay(100);
1395 goto restart;
1398 * clear the LRU reference count so the bufer doesn't get
1399 * ignored in xfs_buf_rele().
1401 atomic_set(&bp->b_lru_ref, 0);
1402 spin_unlock(&btp->bt_lru_lock);
1403 xfs_buf_rele(bp);
1404 spin_lock(&btp->bt_lru_lock);
1406 spin_unlock(&btp->bt_lru_lock);
1410 xfs_buftarg_shrink(
1411 struct shrinker *shrink,
1412 struct shrink_control *sc)
1414 struct xfs_buftarg *btp = container_of(shrink,
1415 struct xfs_buftarg, bt_shrinker);
1416 struct xfs_buf *bp;
1417 int nr_to_scan = sc->nr_to_scan;
1418 LIST_HEAD(dispose);
1420 if (!nr_to_scan)
1421 return btp->bt_lru_nr;
1423 spin_lock(&btp->bt_lru_lock);
1424 while (!list_empty(&btp->bt_lru)) {
1425 if (nr_to_scan-- <= 0)
1426 break;
1428 bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru);
1431 * Decrement the b_lru_ref count unless the value is already
1432 * zero. If the value is already zero, we need to reclaim the
1433 * buffer, otherwise it gets another trip through the LRU.
1435 if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1436 list_move_tail(&bp->b_lru, &btp->bt_lru);
1437 continue;
1441 * remove the buffer from the LRU now to avoid needing another
1442 * lock round trip inside xfs_buf_rele().
1444 list_move(&bp->b_lru, &dispose);
1445 btp->bt_lru_nr--;
1447 spin_unlock(&btp->bt_lru_lock);
1449 while (!list_empty(&dispose)) {
1450 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1451 list_del_init(&bp->b_lru);
1452 xfs_buf_rele(bp);
1455 return btp->bt_lru_nr;
1458 void
1459 xfs_free_buftarg(
1460 struct xfs_mount *mp,
1461 struct xfs_buftarg *btp)
1463 unregister_shrinker(&btp->bt_shrinker);
1465 xfs_flush_buftarg(btp, 1);
1466 if (mp->m_flags & XFS_MOUNT_BARRIER)
1467 xfs_blkdev_issue_flush(btp);
1469 kthread_stop(btp->bt_task);
1470 kmem_free(btp);
1473 STATIC int
1474 xfs_setsize_buftarg_flags(
1475 xfs_buftarg_t *btp,
1476 unsigned int blocksize,
1477 unsigned int sectorsize,
1478 int verbose)
1480 btp->bt_bsize = blocksize;
1481 btp->bt_sshift = ffs(sectorsize) - 1;
1482 btp->bt_smask = sectorsize - 1;
1484 if (set_blocksize(btp->bt_bdev, sectorsize)) {
1485 xfs_warn(btp->bt_mount,
1486 "Cannot set_blocksize to %u on device %s\n",
1487 sectorsize, XFS_BUFTARG_NAME(btp));
1488 return EINVAL;
1491 return 0;
1495 * When allocating the initial buffer target we have not yet
1496 * read in the superblock, so don't know what sized sectors
1497 * are being used is at this early stage. Play safe.
1499 STATIC int
1500 xfs_setsize_buftarg_early(
1501 xfs_buftarg_t *btp,
1502 struct block_device *bdev)
1504 return xfs_setsize_buftarg_flags(btp,
1505 PAGE_SIZE, bdev_logical_block_size(bdev), 0);
1509 xfs_setsize_buftarg(
1510 xfs_buftarg_t *btp,
1511 unsigned int blocksize,
1512 unsigned int sectorsize)
1514 return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1);
1517 STATIC int
1518 xfs_alloc_delwrite_queue(
1519 xfs_buftarg_t *btp,
1520 const char *fsname)
1522 INIT_LIST_HEAD(&btp->bt_delwrite_queue);
1523 spin_lock_init(&btp->bt_delwrite_lock);
1524 btp->bt_flags = 0;
1525 btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd/%s", fsname);
1526 if (IS_ERR(btp->bt_task))
1527 return PTR_ERR(btp->bt_task);
1528 return 0;
1531 xfs_buftarg_t *
1532 xfs_alloc_buftarg(
1533 struct xfs_mount *mp,
1534 struct block_device *bdev,
1535 int external,
1536 const char *fsname)
1538 xfs_buftarg_t *btp;
1540 btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
1542 btp->bt_mount = mp;
1543 btp->bt_dev = bdev->bd_dev;
1544 btp->bt_bdev = bdev;
1545 btp->bt_bdi = blk_get_backing_dev_info(bdev);
1546 if (!btp->bt_bdi)
1547 goto error;
1549 INIT_LIST_HEAD(&btp->bt_lru);
1550 spin_lock_init(&btp->bt_lru_lock);
1551 if (xfs_setsize_buftarg_early(btp, bdev))
1552 goto error;
1553 if (xfs_alloc_delwrite_queue(btp, fsname))
1554 goto error;
1555 btp->bt_shrinker.shrink = xfs_buftarg_shrink;
1556 btp->bt_shrinker.seeks = DEFAULT_SEEKS;
1557 register_shrinker(&btp->bt_shrinker);
1558 return btp;
1560 error:
1561 kmem_free(btp);
1562 return NULL;
1567 * Delayed write buffer handling
1569 STATIC void
1570 xfs_buf_delwri_queue(
1571 xfs_buf_t *bp,
1572 int unlock)
1574 struct list_head *dwq = &bp->b_target->bt_delwrite_queue;
1575 spinlock_t *dwlk = &bp->b_target->bt_delwrite_lock;
1577 trace_xfs_buf_delwri_queue(bp, _RET_IP_);
1579 ASSERT((bp->b_flags&(XBF_DELWRI|XBF_ASYNC)) == (XBF_DELWRI|XBF_ASYNC));
1581 spin_lock(dwlk);
1582 /* If already in the queue, dequeue and place at tail */
1583 if (!list_empty(&bp->b_list)) {
1584 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1585 if (unlock)
1586 atomic_dec(&bp->b_hold);
1587 list_del(&bp->b_list);
1590 if (list_empty(dwq)) {
1591 /* start xfsbufd as it is about to have something to do */
1592 wake_up_process(bp->b_target->bt_task);
1595 bp->b_flags |= _XBF_DELWRI_Q;
1596 list_add_tail(&bp->b_list, dwq);
1597 bp->b_queuetime = jiffies;
1598 spin_unlock(dwlk);
1600 if (unlock)
1601 xfs_buf_unlock(bp);
1604 void
1605 xfs_buf_delwri_dequeue(
1606 xfs_buf_t *bp)
1608 spinlock_t *dwlk = &bp->b_target->bt_delwrite_lock;
1609 int dequeued = 0;
1611 spin_lock(dwlk);
1612 if ((bp->b_flags & XBF_DELWRI) && !list_empty(&bp->b_list)) {
1613 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1614 list_del_init(&bp->b_list);
1615 dequeued = 1;
1617 bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
1618 spin_unlock(dwlk);
1620 if (dequeued)
1621 xfs_buf_rele(bp);
1623 trace_xfs_buf_delwri_dequeue(bp, _RET_IP_);
1627 * If a delwri buffer needs to be pushed before it has aged out, then promote
1628 * it to the head of the delwri queue so that it will be flushed on the next
1629 * xfsbufd run. We do this by resetting the queuetime of the buffer to be older
1630 * than the age currently needed to flush the buffer. Hence the next time the
1631 * xfsbufd sees it is guaranteed to be considered old enough to flush.
1633 void
1634 xfs_buf_delwri_promote(
1635 struct xfs_buf *bp)
1637 struct xfs_buftarg *btp = bp->b_target;
1638 long age = xfs_buf_age_centisecs * msecs_to_jiffies(10) + 1;
1640 ASSERT(bp->b_flags & XBF_DELWRI);
1641 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1644 * Check the buffer age before locking the delayed write queue as we
1645 * don't need to promote buffers that are already past the flush age.
1647 if (bp->b_queuetime < jiffies - age)
1648 return;
1649 bp->b_queuetime = jiffies - age;
1650 spin_lock(&btp->bt_delwrite_lock);
1651 list_move(&bp->b_list, &btp->bt_delwrite_queue);
1652 spin_unlock(&btp->bt_delwrite_lock);
1655 STATIC void
1656 xfs_buf_runall_queues(
1657 struct workqueue_struct *queue)
1659 flush_workqueue(queue);
1663 * Move as many buffers as specified to the supplied list
1664 * idicating if we skipped any buffers to prevent deadlocks.
1666 STATIC int
1667 xfs_buf_delwri_split(
1668 xfs_buftarg_t *target,
1669 struct list_head *list,
1670 unsigned long age)
1672 xfs_buf_t *bp, *n;
1673 struct list_head *dwq = &target->bt_delwrite_queue;
1674 spinlock_t *dwlk = &target->bt_delwrite_lock;
1675 int skipped = 0;
1676 int force;
1678 force = test_and_clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1679 INIT_LIST_HEAD(list);
1680 spin_lock(dwlk);
1681 list_for_each_entry_safe(bp, n, dwq, b_list) {
1682 ASSERT(bp->b_flags & XBF_DELWRI);
1684 if (!XFS_BUF_ISPINNED(bp) && xfs_buf_trylock(bp)) {
1685 if (!force &&
1686 time_before(jiffies, bp->b_queuetime + age)) {
1687 xfs_buf_unlock(bp);
1688 break;
1691 bp->b_flags &= ~(XBF_DELWRI | _XBF_DELWRI_Q);
1692 bp->b_flags |= XBF_WRITE;
1693 list_move_tail(&bp->b_list, list);
1694 trace_xfs_buf_delwri_split(bp, _RET_IP_);
1695 } else
1696 skipped++;
1698 spin_unlock(dwlk);
1700 return skipped;
1705 * Compare function is more complex than it needs to be because
1706 * the return value is only 32 bits and we are doing comparisons
1707 * on 64 bit values
1709 static int
1710 xfs_buf_cmp(
1711 void *priv,
1712 struct list_head *a,
1713 struct list_head *b)
1715 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
1716 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
1717 xfs_daddr_t diff;
1719 diff = ap->b_bn - bp->b_bn;
1720 if (diff < 0)
1721 return -1;
1722 if (diff > 0)
1723 return 1;
1724 return 0;
1727 STATIC int
1728 xfsbufd(
1729 void *data)
1731 xfs_buftarg_t *target = (xfs_buftarg_t *)data;
1733 current->flags |= PF_MEMALLOC;
1735 set_freezable();
1737 do {
1738 long age = xfs_buf_age_centisecs * msecs_to_jiffies(10);
1739 long tout = xfs_buf_timer_centisecs * msecs_to_jiffies(10);
1740 struct list_head tmp;
1741 struct blk_plug plug;
1743 if (unlikely(freezing(current))) {
1744 set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1745 refrigerator();
1746 } else {
1747 clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1750 /* sleep for a long time if there is nothing to do. */
1751 if (list_empty(&target->bt_delwrite_queue))
1752 tout = MAX_SCHEDULE_TIMEOUT;
1753 schedule_timeout_interruptible(tout);
1755 xfs_buf_delwri_split(target, &tmp, age);
1756 list_sort(NULL, &tmp, xfs_buf_cmp);
1758 blk_start_plug(&plug);
1759 while (!list_empty(&tmp)) {
1760 struct xfs_buf *bp;
1761 bp = list_first_entry(&tmp, struct xfs_buf, b_list);
1762 list_del_init(&bp->b_list);
1763 xfs_bdstrat_cb(bp);
1765 blk_finish_plug(&plug);
1766 } while (!kthread_should_stop());
1768 return 0;
1772 * Go through all incore buffers, and release buffers if they belong to
1773 * the given device. This is used in filesystem error handling to
1774 * preserve the consistency of its metadata.
1777 xfs_flush_buftarg(
1778 xfs_buftarg_t *target,
1779 int wait)
1781 xfs_buf_t *bp;
1782 int pincount = 0;
1783 LIST_HEAD(tmp_list);
1784 LIST_HEAD(wait_list);
1785 struct blk_plug plug;
1787 xfs_buf_runall_queues(xfsconvertd_workqueue);
1788 xfs_buf_runall_queues(xfsdatad_workqueue);
1789 xfs_buf_runall_queues(xfslogd_workqueue);
1791 set_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1792 pincount = xfs_buf_delwri_split(target, &tmp_list, 0);
1795 * Dropped the delayed write list lock, now walk the temporary list.
1796 * All I/O is issued async and then if we need to wait for completion
1797 * we do that after issuing all the IO.
1799 list_sort(NULL, &tmp_list, xfs_buf_cmp);
1801 blk_start_plug(&plug);
1802 while (!list_empty(&tmp_list)) {
1803 bp = list_first_entry(&tmp_list, struct xfs_buf, b_list);
1804 ASSERT(target == bp->b_target);
1805 list_del_init(&bp->b_list);
1806 if (wait) {
1807 bp->b_flags &= ~XBF_ASYNC;
1808 list_add(&bp->b_list, &wait_list);
1810 xfs_bdstrat_cb(bp);
1812 blk_finish_plug(&plug);
1814 if (wait) {
1815 /* Wait for IO to complete. */
1816 while (!list_empty(&wait_list)) {
1817 bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
1819 list_del_init(&bp->b_list);
1820 xfs_buf_iowait(bp);
1821 xfs_buf_relse(bp);
1825 return pincount;
1828 int __init
1829 xfs_buf_init(void)
1831 xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
1832 KM_ZONE_HWALIGN, NULL);
1833 if (!xfs_buf_zone)
1834 goto out;
1836 xfslogd_workqueue = alloc_workqueue("xfslogd",
1837 WQ_MEM_RECLAIM | WQ_HIGHPRI, 1);
1838 if (!xfslogd_workqueue)
1839 goto out_free_buf_zone;
1841 xfsdatad_workqueue = alloc_workqueue("xfsdatad", WQ_MEM_RECLAIM, 1);
1842 if (!xfsdatad_workqueue)
1843 goto out_destroy_xfslogd_workqueue;
1845 xfsconvertd_workqueue = alloc_workqueue("xfsconvertd",
1846 WQ_MEM_RECLAIM, 1);
1847 if (!xfsconvertd_workqueue)
1848 goto out_destroy_xfsdatad_workqueue;
1850 return 0;
1852 out_destroy_xfsdatad_workqueue:
1853 destroy_workqueue(xfsdatad_workqueue);
1854 out_destroy_xfslogd_workqueue:
1855 destroy_workqueue(xfslogd_workqueue);
1856 out_free_buf_zone:
1857 kmem_zone_destroy(xfs_buf_zone);
1858 out:
1859 return -ENOMEM;
1862 void
1863 xfs_buf_terminate(void)
1865 destroy_workqueue(xfsconvertd_workqueue);
1866 destroy_workqueue(xfsdatad_workqueue);
1867 destroy_workqueue(xfslogd_workqueue);
1868 kmem_zone_destroy(xfs_buf_zone);
1871 #ifdef CONFIG_KDB_MODULES
1872 struct list_head *
1873 xfs_get_buftarg_list(void)
1875 return &xfs_buftarg_list;
1877 #endif