aboutsummaryrefslogtreecommitdiffstats
path: root/fs/xfs/xfs_buf.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/xfs/xfs_buf.c')
-rw-r--r--fs/xfs/xfs_buf.c1876
1 files changed, 1876 insertions, 0 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
new file mode 100644
index 000000000000..c57836dc778f
--- /dev/null
+++ b/fs/xfs/xfs_buf.c
@@ -0,0 +1,1876 @@
1/*
2 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
3 * All Rights Reserved.
4 *
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.
8 *
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.
13 *
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
17 */
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>
36
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"
43
44static kmem_zone_t *xfs_buf_zone;
45STATIC int xfsbufd(void *);
46STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
47
48static struct workqueue_struct *xfslogd_workqueue;
49struct workqueue_struct *xfsdatad_workqueue;
50struct workqueue_struct *xfsconvertd_workqueue;
51
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
61
62#define xb_to_gfp(flags) \
63 ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
64 ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
65
66#define xb_to_km(flags) \
67 (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
68
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));
73
74static inline int
75xfs_buf_is_vmapped(
76 struct xfs_buf *bp)
77{
78 /*
79 * Return true if the buffer is vmapped.
80 *
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.
84 */
85 return (bp->b_flags & XBF_MAPPED) && bp->b_page_count > 1;
86}
87
88static inline int
89xfs_buf_vmap_len(
90 struct xfs_buf *bp)
91{
92 return (bp->b_page_count * PAGE_SIZE) - bp->b_offset;
93}
94
95/*
96 * xfs_buf_lru_add - add a buffer to the LRU.
97 *
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.
100 */
101STATIC void
102xfs_buf_lru_add(
103 struct xfs_buf *bp)
104{
105 struct xfs_buftarg *btp = bp->b_target;
106
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++;
112 }
113 spin_unlock(&btp->bt_lru_lock);
114}
115
116/*
117 * xfs_buf_lru_del - remove a buffer from the LRU
118 *
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.
124 */
125STATIC void
126xfs_buf_lru_del(
127 struct xfs_buf *bp)
128{
129 struct xfs_buftarg *btp = bp->b_target;
130
131 if (list_empty(&bp->b_lru))
132 return;
133
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--;
138 }
139 spin_unlock(&btp->bt_lru_lock);
140}
141
142/*
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.
147 *
148 * This prevents build-up of stale buffers on the LRU.
149 */
150void
151xfs_buf_stale(
152 struct xfs_buf *bp)
153{
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;
158
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);
164 }
165 spin_unlock(&btp->bt_lru_lock);
166 }
167 ASSERT(atomic_read(&bp->b_hold) >= 1);
168}
169
170STATIC 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)
177{
178 /*
179 * We don't want certain flags to appear in b_flags.
180 */
181 flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
182
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;
194 /*
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).
198 */
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);
204
205 XFS_STATS_INC(xb_create);
206
207 trace_xfs_buf_init(bp, _RET_IP_);
208}
209
210/*
211 * Allocate a page array capable of holding a specified number
212 * of pages, and point the page buf at it.
213 */
214STATIC int
215_xfs_buf_get_pages(
216 xfs_buf_t *bp,
217 int page_count,
218 xfs_buf_flags_t flags)
219{
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;
231 }
232 memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
233 }
234 return 0;
235}
236
237/*
238 * Frees b_pages if it was allocated.
239 */
240STATIC void
241_xfs_buf_free_pages(
242 xfs_buf_t *bp)
243{
244 if (bp->b_pages != bp->b_page_array) {
245 kmem_free(bp->b_pages);
246 bp->b_pages = NULL;
247 }
248}
249
250/*
251 * Releases the specified buffer.
252 *
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
256 */
257void
258xfs_buf_free(
259 xfs_buf_t *bp)
260{
261 trace_xfs_buf_free(bp, _RET_IP_);
262
263 ASSERT(list_empty(&bp->b_lru));
264
265 if (bp->b_flags & _XBF_PAGES) {
266 uint i;
267
268 if (xfs_buf_is_vmapped(bp))
269 vm_unmap_ram(bp->b_addr - bp->b_offset,
270 bp->b_page_count);
271
272 for (i = 0; i < bp->b_page_count; i++) {
273 struct page *page = bp->b_pages[i];
274
275 __free_page(page);
276 }
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);
281}
282
283/*
284 * Allocates all the pages for buffer in question and builds it's page list.
285 */
286STATIC int
287xfs_buf_allocate_memory(
288 xfs_buf_t *bp,
289 uint flags)
290{
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;
297
298 /*
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.
302 */
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;
308 }
309
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;
317 }
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;
324 }
325
326use_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;
332
333 offset = bp->b_offset;
334 bp->b_flags |= _XBF_PAGES;
335
336 for (i = 0; i < bp->b_page_count; i++) {
337 struct page *page;
338 uint retries = 0;
339retry:
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;
346 }
347
348 /*
349 * This could deadlock.
350 *
351 * But until all the XFS lowlevel code is revamped to
352 * handle buffer allocation failures we can't do much.
353 */
354 if (!(++retries % 100))
355 xfs_err(NULL,
356 "possible memory allocation deadlock in %s (mode:0x%x)",
357 __func__, gfp_mask);
358
359 XFS_STATS_INC(xb_page_retries);
360 congestion_wait(BLK_RW_ASYNC, HZ/50);
361 goto retry;
362 }
363
364 XFS_STATS_INC(xb_page_found);
365
366 nbytes = min_t(size_t, size, PAGE_SIZE - offset);
367 size -= nbytes;
368 bp->b_pages[i] = page;
369 offset = 0;
370 }
371 return 0;
372
373out_free_pages:
374 for (i = 0; i < bp->b_page_count; i++)
375 __free_page(bp->b_pages[i]);
376 return error;
377}
378
379/*
380 * Map buffer into kernel address-space if necessary.
381 */
382STATIC int
383_xfs_buf_map_pages(
384 xfs_buf_t *bp,
385 uint flags)
386{
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;
394
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);
402
403 if (!bp->b_addr)
404 return -ENOMEM;
405 bp->b_addr += bp->b_offset;
406 bp->b_flags |= XBF_MAPPED;
407 }
408
409 return 0;
410}
411
412/*
413 * Finding and Reading Buffers
414 */
415
416/*
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.
423 */
424xfs_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)
431{
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;
438
439 range_base = (ioff << BBSHIFT);
440 range_length = (isize << BBSHIFT);
441
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));
445
446 /* get tree root */
447 pag = xfs_perag_get(btp->bt_mount,
448 xfs_daddr_to_agno(btp->bt_mount, ioff));
449
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);
458
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 {
464 /*
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.
471 */
472 if (bp->b_buffer_length != range_length) {
473 ASSERT(bp->b_flags & XBF_STALE);
474 rbp = &(*rbp)->rb_right;
475 continue;
476 }
477 atomic_inc(&bp->b_hold);
478 goto found;
479 }
480 }
481
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);
495 }
496 return new_bp;
497
498found:
499 spin_unlock(&pag->pag_buf_lock);
500 xfs_perag_put(pag);
501
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;
507 }
508 xfs_buf_lock(bp);
509 XFS_STATS_INC(xb_get_locked_waited);
510 }
511
512 /*
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.
516 */
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;
520 }
521
522 trace_xfs_buf_find(bp, flags, _RET_IP_);
523 XFS_STATS_INC(xb_get_locked);
524 return bp;
525}
526
527/*
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.
531 */
532xfs_buf_t *
533xfs_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)
538{
539 xfs_buf_t *bp, *new_bp;
540 int error = 0;
541
542 new_bp = xfs_buf_allocate(flags);
543 if (unlikely(!new_bp))
544 return NULL;
545
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;
555 }
556
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;
563 }
564 }
565
566 XFS_STATS_INC(xb_get);
567
568 /*
569 * Always fill in the block number now, the mapped cases can do
570 * their own overlay of this later.
571 */
572 bp->b_bn = ioff;
573 bp->b_count_desired = bp->b_buffer_length;
574
575 trace_xfs_buf_get(bp, flags, _RET_IP_);
576 return bp;
577
578 no_buffer:
579 if (flags & (XBF_LOCK | XBF_TRYLOCK))
580 xfs_buf_unlock(bp);
581 xfs_buf_rele(bp);
582 return NULL;
583}
584
585STATIC int
586_xfs_buf_read(
587 xfs_buf_t *bp,
588 xfs_buf_flags_t flags)
589{
590 int status;
591
592 ASSERT(!(flags & (XBF_DELWRI|XBF_WRITE)));
593 ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);
594
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);
597
598 status = xfs_buf_iorequest(bp);
599 if (status || bp->b_error || (flags & XBF_ASYNC))
600 return status;
601 return xfs_buf_iowait(bp);
602}
603
604xfs_buf_t *
605xfs_buf_read(
606 xfs_buftarg_t *target,
607 xfs_off_t ioff,
608 size_t isize,
609 xfs_buf_flags_t flags)
610{
611 xfs_buf_t *bp;
612
613 flags |= XBF_READ;
614
615 bp = xfs_buf_get(target, ioff, isize, flags);
616 if (bp) {
617 trace_xfs_buf_read(bp, flags, _RET_IP_);
618
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) {
623 /*
624 * Read ahead call which is already satisfied,
625 * drop the buffer
626 */
627 goto no_buffer;
628 } else {
629 /* We do not want read in the flags */
630 bp->b_flags &= ~XBF_READ;
631 }
632 }
633
634 return bp;
635
636 no_buffer:
637 if (flags & (XBF_LOCK | XBF_TRYLOCK))
638 xfs_buf_unlock(bp);
639 xfs_buf_rele(bp);
640 return NULL;
641}
642
643/*
644 * If we are not low on memory then do the readahead in a deadlock
645 * safe manner.
646 */
647void
648xfs_buf_readahead(
649 xfs_buftarg_t *target,
650 xfs_off_t ioff,
651 size_t isize)
652{
653 if (bdi_read_congested(target->bt_bdi))
654 return;
655
656 xfs_buf_read(target, ioff, isize,
657 XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD|XBF_DONT_BLOCK);
658}
659
660/*
661 * Read an uncached buffer from disk. Allocates and returns a locked
662 * buffer containing the disk contents or nothing.
663 */
664struct xfs_buf *
665xfs_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)
671{
672 xfs_buf_t *bp;
673 int error;
674
675 bp = xfs_buf_get_uncached(target, length, flags);
676 if (!bp)
677 return NULL;
678
679 /* set up the buffer for a read IO */
680 XFS_BUF_SET_ADDR(bp, daddr);
681 XFS_BUF_READ(bp);
682
683 xfsbdstrat(mp, bp);
684 error = xfs_buf_iowait(bp);
685 if (error || bp->b_error) {
686 xfs_buf_relse(bp);
687 return NULL;
688 }
689 return bp;
690}
691
692xfs_buf_t *
693xfs_buf_get_empty(
694 size_t len,
695 xfs_buftarg_t *target)
696{
697 xfs_buf_t *bp;
698
699 bp = xfs_buf_allocate(0);
700 if (bp)
701 _xfs_buf_initialize(bp, target, 0, len, 0);
702 return bp;
703}
704
705/*
706 * Return a buffer allocated as an empty buffer and associated to external
707 * memory via xfs_buf_associate_memory() back to it's empty state.
708 */
709void
710xfs_buf_set_empty(
711 struct xfs_buf *bp,
712 size_t len)
713{
714 if (bp->b_pages)
715 _xfs_buf_free_pages(bp);
716
717 bp->b_pages = NULL;
718 bp->b_page_count = 0;
719 bp->b_addr = NULL;
720 bp->b_file_offset = 0;
721 bp->b_buffer_length = bp->b_count_desired = len;
722 bp->b_bn = XFS_BUF_DADDR_NULL;
723 bp->b_flags &= ~XBF_MAPPED;
724}
725
726static inline struct page *
727mem_to_page(
728 void *addr)
729{
730 if ((!is_vmalloc_addr(addr))) {
731 return virt_to_page(addr);
732 } else {
733 return vmalloc_to_page(addr);
734 }
735}
736
737int
738xfs_buf_associate_memory(
739 xfs_buf_t *bp,
740 void *mem,
741 size_t len)
742{
743 int rval;
744 int i = 0;
745 unsigned long pageaddr;
746 unsigned long offset;
747 size_t buflen;
748 int page_count;
749
750 pageaddr = (unsigned long)mem & PAGE_MASK;
751 offset = (unsigned long)mem - pageaddr;
752 buflen = PAGE_ALIGN(len + offset);
753 page_count = buflen >> PAGE_SHIFT;
754
755 /* Free any previous set of page pointers */
756 if (bp->b_pages)
757 _xfs_buf_free_pages(bp);
758
759 bp->b_pages = NULL;
760 bp->b_addr = mem;
761
762 rval = _xfs_buf_get_pages(bp, page_count, XBF_DONT_BLOCK);
763 if (rval)
764 return rval;
765
766 bp->b_offset = offset;
767
768 for (i = 0; i < bp->b_page_count; i++) {
769 bp->b_pages[i] = mem_to_page((void *)pageaddr);
770 pageaddr += PAGE_SIZE;
771 }
772
773 bp->b_count_desired = len;
774 bp->b_buffer_length = buflen;
775 bp->b_flags |= XBF_MAPPED;
776
777 return 0;
778}
779
780xfs_buf_t *
781xfs_buf_get_uncached(
782 struct xfs_buftarg *target,
783 size_t len,
784 int flags)
785{
786 unsigned long page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
787 int error, i;
788 xfs_buf_t *bp;
789
790 bp = xfs_buf_allocate(0);
791 if (unlikely(bp == NULL))
792 goto fail;
793 _xfs_buf_initialize(bp, target, 0, len, 0);
794
795 error = _xfs_buf_get_pages(bp, page_count, 0);
796 if (error)
797 goto fail_free_buf;
798
799 for (i = 0; i < page_count; i++) {
800 bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
801 if (!bp->b_pages[i])
802 goto fail_free_mem;
803 }
804 bp->b_flags |= _XBF_PAGES;
805
806 error = _xfs_buf_map_pages(bp, XBF_MAPPED);
807 if (unlikely(error)) {
808 xfs_warn(target->bt_mount,
809 "%s: failed to map pages\n", __func__);
810 goto fail_free_mem;
811 }
812
813 trace_xfs_buf_get_uncached(bp, _RET_IP_);
814 return bp;
815
816 fail_free_mem:
817 while (--i >= 0)
818 __free_page(bp->b_pages[i]);
819 _xfs_buf_free_pages(bp);
820 fail_free_buf:
821 xfs_buf_deallocate(bp);
822 fail:
823 return NULL;
824}
825
826/*
827 * Increment reference count on buffer, to hold the buffer concurrently
828 * with another thread which may release (free) the buffer asynchronously.
829 * Must hold the buffer already to call this function.
830 */
831void
832xfs_buf_hold(
833 xfs_buf_t *bp)
834{
835 trace_xfs_buf_hold(bp, _RET_IP_);
836 atomic_inc(&bp->b_hold);
837}
838
839/*
840 * Releases a hold on the specified buffer. If the
841 * the hold count is 1, calls xfs_buf_free.
842 */
843void
844xfs_buf_rele(
845 xfs_buf_t *bp)
846{
847 struct xfs_perag *pag = bp->b_pag;
848
849 trace_xfs_buf_rele(bp, _RET_IP_);
850
851 if (!pag) {
852 ASSERT(list_empty(&bp->b_lru));
853 ASSERT(RB_EMPTY_NODE(&bp->b_rbnode));
854 if (atomic_dec_and_test(&bp->b_hold))
855 xfs_buf_free(bp);
856 return;
857 }
858
859 ASSERT(!RB_EMPTY_NODE(&bp->b_rbnode));
860
861 ASSERT(atomic_read(&bp->b_hold) > 0);
862 if (atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock)) {
863 if (!(bp->b_flags & XBF_STALE) &&
864 atomic_read(&bp->b_lru_ref)) {
865 xfs_buf_lru_add(bp);
866 spin_unlock(&pag->pag_buf_lock);
867 } else {
868 xfs_buf_lru_del(bp);
869 ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)));
870 rb_erase(&bp->b_rbnode, &pag->pag_buf_tree);
871 spin_unlock(&pag->pag_buf_lock);
872 xfs_perag_put(pag);
873 xfs_buf_free(bp);
874 }
875 }
876}
877
878
879/*
880 * Lock a buffer object, if it is not already locked.
881 *
882 * If we come across a stale, pinned, locked buffer, we know that we are
883 * being asked to lock a buffer that has been reallocated. Because it is
884 * pinned, we know that the log has not been pushed to disk and hence it
885 * will still be locked. Rather than continuing to have trylock attempts
886 * fail until someone else pushes the log, push it ourselves before
887 * returning. This means that the xfsaild will not get stuck trying
888 * to push on stale inode buffers.
889 */
890int
891xfs_buf_trylock(
892 struct xfs_buf *bp)
893{
894 int locked;
895
896 locked = down_trylock(&bp->b_sema) == 0;
897 if (locked)
898 XB_SET_OWNER(bp);
899 else if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
900 xfs_log_force(bp->b_target->bt_mount, 0);
901
902 trace_xfs_buf_trylock(bp, _RET_IP_);
903 return locked;
904}
905
906/*
907 * Lock a buffer object.
908 *
909 * If we come across a stale, pinned, locked buffer, we know that we
910 * are being asked to lock a buffer that has been reallocated. Because
911 * it is pinned, we know that the log has not been pushed to disk and
912 * hence it will still be locked. Rather than sleeping until someone
913 * else pushes the log, push it ourselves before trying to get the lock.
914 */
915void
916xfs_buf_lock(
917 struct xfs_buf *bp)
918{
919 trace_xfs_buf_lock(bp, _RET_IP_);
920
921 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
922 xfs_log_force(bp->b_target->bt_mount, 0);
923 down(&bp->b_sema);
924 XB_SET_OWNER(bp);
925
926 trace_xfs_buf_lock_done(bp, _RET_IP_);
927}
928
929/*
930 * Releases the lock on the buffer object.
931 * If the buffer is marked delwri but is not queued, do so before we
932 * unlock the buffer as we need to set flags correctly. We also need to
933 * take a reference for the delwri queue because the unlocker is going to
934 * drop their's and they don't know we just queued it.
935 */
936void
937xfs_buf_unlock(
938 struct xfs_buf *bp)
939{
940 if ((bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)) == XBF_DELWRI) {
941 atomic_inc(&bp->b_hold);
942 bp->b_flags |= XBF_ASYNC;
943 xfs_buf_delwri_queue(bp, 0);
944 }
945
946 XB_CLEAR_OWNER(bp);
947 up(&bp->b_sema);
948
949 trace_xfs_buf_unlock(bp, _RET_IP_);
950}
951
952STATIC void
953xfs_buf_wait_unpin(
954 xfs_buf_t *bp)
955{
956 DECLARE_WAITQUEUE (wait, current);
957
958 if (atomic_read(&bp->b_pin_count) == 0)
959 return;
960
961 add_wait_queue(&bp->b_waiters, &wait);
962 for (;;) {
963 set_current_state(TASK_UNINTERRUPTIBLE);
964 if (atomic_read(&bp->b_pin_count) == 0)
965 break;
966 io_schedule();
967 }
968 remove_wait_queue(&bp->b_waiters, &wait);
969 set_current_state(TASK_RUNNING);
970}
971
972/*
973 * Buffer Utility Routines
974 */
975
976STATIC void
977xfs_buf_iodone_work(
978 struct work_struct *work)
979{
980 xfs_buf_t *bp =
981 container_of(work, xfs_buf_t, b_iodone_work);
982
983 if (bp->b_iodone)
984 (*(bp->b_iodone))(bp);
985 else if (bp->b_flags & XBF_ASYNC)
986 xfs_buf_relse(bp);
987}
988
989void
990xfs_buf_ioend(
991 xfs_buf_t *bp,
992 int schedule)
993{
994 trace_xfs_buf_iodone(bp, _RET_IP_);
995
996 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
997 if (bp->b_error == 0)
998 bp->b_flags |= XBF_DONE;
999
1000 if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
1001 if (schedule) {
1002 INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
1003 queue_work(xfslogd_workqueue, &bp->b_iodone_work);
1004 } else {
1005 xfs_buf_iodone_work(&bp->b_iodone_work);
1006 }
1007 } else {
1008 complete(&bp->b_iowait);
1009 }
1010}
1011
1012void
1013xfs_buf_ioerror(
1014 xfs_buf_t *bp,
1015 int error)
1016{
1017 ASSERT(error >= 0 && error <= 0xffff);
1018 bp->b_error = (unsigned short)error;
1019 trace_xfs_buf_ioerror(bp, error, _RET_IP_);
1020}
1021
1022int
1023xfs_bwrite(
1024 struct xfs_mount *mp,
1025 struct xfs_buf *bp)
1026{
1027 int error;
1028
1029 bp->b_flags |= XBF_WRITE;
1030 bp->b_flags &= ~(XBF_ASYNC | XBF_READ);
1031
1032 xfs_buf_delwri_dequeue(bp);
1033 xfs_bdstrat_cb(bp);
1034
1035 error = xfs_buf_iowait(bp);
1036 if (error)
1037 xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1038 xfs_buf_relse(bp);
1039 return error;
1040}
1041
1042void
1043xfs_bdwrite(
1044 void *mp,
1045 struct xfs_buf *bp)
1046{
1047 trace_xfs_buf_bdwrite(bp, _RET_IP_);
1048
1049 bp->b_flags &= ~XBF_READ;
1050 bp->b_flags |= (XBF_DELWRI | XBF_ASYNC);
1051
1052 xfs_buf_delwri_queue(bp, 1);
1053}
1054
1055/*
1056 * Called when we want to stop a buffer from getting written or read.
1057 * We attach the EIO error, muck with its flags, and call xfs_buf_ioend
1058 * so that the proper iodone callbacks get called.
1059 */
1060STATIC int
1061xfs_bioerror(
1062 xfs_buf_t *bp)
1063{
1064#ifdef XFSERRORDEBUG
1065 ASSERT(XFS_BUF_ISREAD(bp) || bp->b_iodone);
1066#endif
1067
1068 /*
1069 * No need to wait until the buffer is unpinned, we aren't flushing it.
1070 */
1071 xfs_buf_ioerror(bp, EIO);
1072
1073 /*
1074 * We're calling xfs_buf_ioend, so delete XBF_DONE flag.
1075 */
1076 XFS_BUF_UNREAD(bp);
1077 XFS_BUF_UNDELAYWRITE(bp);
1078 XFS_BUF_UNDONE(bp);
1079 XFS_BUF_STALE(bp);
1080
1081 xfs_buf_ioend(bp, 0);
1082
1083 return EIO;
1084}
1085
1086/*
1087 * Same as xfs_bioerror, except that we are releasing the buffer
1088 * here ourselves, and avoiding the xfs_buf_ioend call.
1089 * This is meant for userdata errors; metadata bufs come with
1090 * iodone functions attached, so that we can track down errors.
1091 */
1092STATIC int
1093xfs_bioerror_relse(
1094 struct xfs_buf *bp)
1095{
1096 int64_t fl = bp->b_flags;
1097 /*
1098 * No need to wait until the buffer is unpinned.
1099 * We aren't flushing it.
1100 *
1101 * chunkhold expects B_DONE to be set, whether
1102 * we actually finish the I/O or not. We don't want to
1103 * change that interface.
1104 */
1105 XFS_BUF_UNREAD(bp);
1106 XFS_BUF_UNDELAYWRITE(bp);
1107 XFS_BUF_DONE(bp);
1108 XFS_BUF_STALE(bp);
1109 bp->b_iodone = NULL;
1110 if (!(fl & XBF_ASYNC)) {
1111 /*
1112 * Mark b_error and B_ERROR _both_.
1113 * Lot's of chunkcache code assumes that.
1114 * There's no reason to mark error for
1115 * ASYNC buffers.
1116 */
1117 xfs_buf_ioerror(bp, EIO);
1118 XFS_BUF_FINISH_IOWAIT(bp);
1119 } else {
1120 xfs_buf_relse(bp);
1121 }
1122
1123 return EIO;
1124}
1125
1126
1127/*
1128 * All xfs metadata buffers except log state machine buffers
1129 * get this attached as their b_bdstrat callback function.
1130 * This is so that we can catch a buffer
1131 * after prematurely unpinning it to forcibly shutdown the filesystem.
1132 */
1133int
1134xfs_bdstrat_cb(
1135 struct xfs_buf *bp)
1136{
1137 if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
1138 trace_xfs_bdstrat_shut(bp, _RET_IP_);
1139 /*
1140 * Metadata write that didn't get logged but
1141 * written delayed anyway. These aren't associated
1142 * with a transaction, and can be ignored.
1143 */
1144 if (!bp->b_iodone && !XFS_BUF_ISREAD(bp))
1145 return xfs_bioerror_relse(bp);
1146 else
1147 return xfs_bioerror(bp);
1148 }
1149
1150 xfs_buf_iorequest(bp);
1151 return 0;
1152}
1153
1154/*
1155 * Wrapper around bdstrat so that we can stop data from going to disk in case
1156 * we are shutting down the filesystem. Typically user data goes thru this
1157 * path; one of the exceptions is the superblock.
1158 */
1159void
1160xfsbdstrat(
1161 struct xfs_mount *mp,
1162 struct xfs_buf *bp)
1163{
1164 if (XFS_FORCED_SHUTDOWN(mp)) {
1165 trace_xfs_bdstrat_shut(bp, _RET_IP_);
1166 xfs_bioerror_relse(bp);
1167 return;
1168 }
1169
1170 xfs_buf_iorequest(bp);
1171}
1172
1173STATIC void
1174_xfs_buf_ioend(
1175 xfs_buf_t *bp,
1176 int schedule)
1177{
1178 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1179 xfs_buf_ioend(bp, schedule);
1180}
1181
1182STATIC void
1183xfs_buf_bio_end_io(
1184 struct bio *bio,
1185 int error)
1186{
1187 xfs_buf_t *bp = (xfs_buf_t *)bio->bi_private;
1188
1189 xfs_buf_ioerror(bp, -error);
1190
1191 if (!error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1192 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1193
1194 _xfs_buf_ioend(bp, 1);
1195 bio_put(bio);
1196}
1197
1198STATIC void
1199_xfs_buf_ioapply(
1200 xfs_buf_t *bp)
1201{
1202 int rw, map_i, total_nr_pages, nr_pages;
1203 struct bio *bio;
1204 int offset = bp->b_offset;
1205 int size = bp->b_count_desired;
1206 sector_t sector = bp->b_bn;
1207
1208 total_nr_pages = bp->b_page_count;
1209 map_i = 0;
1210
1211 if (bp->b_flags & XBF_WRITE) {
1212 if (bp->b_flags & XBF_SYNCIO)
1213 rw = WRITE_SYNC;
1214 else
1215 rw = WRITE;
1216 if (bp->b_flags & XBF_FUA)
1217 rw |= REQ_FUA;
1218 if (bp->b_flags & XBF_FLUSH)
1219 rw |= REQ_FLUSH;
1220 } else if (bp->b_flags & XBF_READ_AHEAD) {
1221 rw = READA;
1222 } else {
1223 rw = READ;
1224 }
1225
1226 /* we only use the buffer cache for meta-data */
1227 rw |= REQ_META;
1228
1229next_chunk:
1230 atomic_inc(&bp->b_io_remaining);
1231 nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
1232 if (nr_pages > total_nr_pages)
1233 nr_pages = total_nr_pages;
1234
1235 bio = bio_alloc(GFP_NOIO, nr_pages);
1236 bio->bi_bdev = bp->b_target->bt_bdev;
1237 bio->bi_sector = sector;
1238 bio->bi_end_io = xfs_buf_bio_end_io;
1239 bio->bi_private = bp;
1240
1241
1242 for (; size && nr_pages; nr_pages--, map_i++) {
1243 int rbytes, nbytes = PAGE_SIZE - offset;
1244
1245 if (nbytes > size)
1246 nbytes = size;
1247
1248 rbytes = bio_add_page(bio, bp->b_pages[map_i], nbytes, offset);
1249 if (rbytes < nbytes)
1250 break;
1251
1252 offset = 0;
1253 sector += nbytes >> BBSHIFT;
1254 size -= nbytes;
1255 total_nr_pages--;
1256 }
1257
1258 if (likely(bio->bi_size)) {
1259 if (xfs_buf_is_vmapped(bp)) {
1260 flush_kernel_vmap_range(bp->b_addr,
1261 xfs_buf_vmap_len(bp));
1262 }
1263 submit_bio(rw, bio);
1264 if (size)
1265 goto next_chunk;
1266 } else {
1267 xfs_buf_ioerror(bp, EIO);
1268 bio_put(bio);
1269 }
1270}
1271
1272int
1273xfs_buf_iorequest(
1274 xfs_buf_t *bp)
1275{
1276 trace_xfs_buf_iorequest(bp, _RET_IP_);
1277
1278 if (bp->b_flags & XBF_DELWRI) {
1279 xfs_buf_delwri_queue(bp, 1);
1280 return 0;
1281 }
1282
1283 if (bp->b_flags & XBF_WRITE) {
1284 xfs_buf_wait_unpin(bp);
1285 }
1286
1287 xfs_buf_hold(bp);
1288
1289 /* Set the count to 1 initially, this will stop an I/O
1290 * completion callout which happens before we have started
1291 * all the I/O from calling xfs_buf_ioend too early.
1292 */
1293 atomic_set(&bp->b_io_remaining, 1);
1294 _xfs_buf_ioapply(bp);
1295 _xfs_buf_ioend(bp, 0);
1296
1297 xfs_buf_rele(bp);
1298 return 0;
1299}
1300
1301/*
1302 * Waits for I/O to complete on the buffer supplied.
1303 * It returns immediately if no I/O is pending.
1304 * It returns the I/O error code, if any, or 0 if there was no error.
1305 */
1306int
1307xfs_buf_iowait(
1308 xfs_buf_t *bp)
1309{
1310 trace_xfs_buf_iowait(bp, _RET_IP_);
1311
1312 wait_for_completion(&bp->b_iowait);
1313
1314 trace_xfs_buf_iowait_done(bp, _RET_IP_);
1315 return bp->b_error;
1316}
1317
1318xfs_caddr_t
1319xfs_buf_offset(
1320 xfs_buf_t *bp,
1321 size_t offset)
1322{
1323 struct page *page;
1324
1325 if (bp->b_flags & XBF_MAPPED)
1326 return bp->b_addr + offset;
1327
1328 offset += bp->b_offset;
1329 page = bp->b_pages[offset >> PAGE_SHIFT];
1330 return (xfs_caddr_t)page_address(page) + (offset & (PAGE_SIZE-1));
1331}
1332
1333/*
1334 * Move data into or out of a buffer.
1335 */
1336void
1337xfs_buf_iomove(
1338 xfs_buf_t *bp, /* buffer to process */
1339 size_t boff, /* starting buffer offset */
1340 size_t bsize, /* length to copy */
1341 void *data, /* data address */
1342 xfs_buf_rw_t mode) /* read/write/zero flag */
1343{
1344 size_t bend, cpoff, csize;
1345 struct page *page;
1346
1347 bend = boff + bsize;
1348 while (boff < bend) {
1349 page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
1350 cpoff = xfs_buf_poff(boff + bp->b_offset);
1351 csize = min_t(size_t,
1352 PAGE_SIZE-cpoff, bp->b_count_desired-boff);
1353
1354 ASSERT(((csize + cpoff) <= PAGE_SIZE));
1355
1356 switch (mode) {
1357 case XBRW_ZERO:
1358 memset(page_address(page) + cpoff, 0, csize);
1359 break;
1360 case XBRW_READ:
1361 memcpy(data, page_address(page) + cpoff, csize);
1362 break;
1363 case XBRW_WRITE:
1364 memcpy(page_address(page) + cpoff, data, csize);
1365 }
1366
1367 boff += csize;
1368 data += csize;
1369 }
1370}
1371
1372/*
1373 * Handling of buffer targets (buftargs).
1374 */
1375
1376/*
1377 * Wait for any bufs with callbacks that have been submitted but have not yet
1378 * returned. These buffers will have an elevated hold count, so wait on those
1379 * while freeing all the buffers only held by the LRU.
1380 */
1381void
1382xfs_wait_buftarg(
1383 struct xfs_buftarg *btp)
1384{
1385 struct xfs_buf *bp;
1386
1387restart:
1388 spin_lock(&btp->bt_lru_lock);
1389 while (!list_empty(&btp->bt_lru)) {
1390 bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru);
1391 if (atomic_read(&bp->b_hold) > 1) {
1392 spin_unlock(&btp->bt_lru_lock);
1393 delay(100);
1394 goto restart;
1395 }
1396 /*
1397 * clear the LRU reference count so the bufer doesn't get
1398 * ignored in xfs_buf_rele().
1399 */
1400 atomic_set(&bp->b_lru_ref, 0);
1401 spin_unlock(&btp->bt_lru_lock);
1402 xfs_buf_rele(bp);
1403 spin_lock(&btp->bt_lru_lock);
1404 }
1405 spin_unlock(&btp->bt_lru_lock);
1406}
1407
1408int
1409xfs_buftarg_shrink(
1410 struct shrinker *shrink,
1411 struct shrink_control *sc)
1412{
1413 struct xfs_buftarg *btp = container_of(shrink,
1414 struct xfs_buftarg, bt_shrinker);
1415 struct xfs_buf *bp;
1416 int nr_to_scan = sc->nr_to_scan;
1417 LIST_HEAD(dispose);
1418
1419 if (!nr_to_scan)
1420 return btp->bt_lru_nr;
1421
1422 spin_lock(&btp->bt_lru_lock);
1423 while (!list_empty(&btp->bt_lru)) {
1424 if (nr_to_scan-- <= 0)
1425 break;
1426
1427 bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru);
1428
1429 /*
1430 * Decrement the b_lru_ref count unless the value is already
1431 * zero. If the value is already zero, we need to reclaim the
1432 * buffer, otherwise it gets another trip through the LRU.
1433 */
1434 if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1435 list_move_tail(&bp->b_lru, &btp->bt_lru);
1436 continue;
1437 }
1438
1439 /*
1440 * remove the buffer from the LRU now to avoid needing another
1441 * lock round trip inside xfs_buf_rele().
1442 */
1443 list_move(&bp->b_lru, &dispose);
1444 btp->bt_lru_nr--;
1445 }
1446 spin_unlock(&btp->bt_lru_lock);
1447
1448 while (!list_empty(&dispose)) {
1449 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1450 list_del_init(&bp->b_lru);
1451 xfs_buf_rele(bp);
1452 }
1453
1454 return btp->bt_lru_nr;
1455}
1456
1457void
1458xfs_free_buftarg(
1459 struct xfs_mount *mp,
1460 struct xfs_buftarg *btp)
1461{
1462 unregister_shrinker(&btp->bt_shrinker);
1463
1464 xfs_flush_buftarg(btp, 1);
1465 if (mp->m_flags & XFS_MOUNT_BARRIER)
1466 xfs_blkdev_issue_flush(btp);
1467
1468 kthread_stop(btp->bt_task);
1469 kmem_free(btp);
1470}
1471
1472STATIC int
1473xfs_setsize_buftarg_flags(
1474 xfs_buftarg_t *btp,
1475 unsigned int blocksize,
1476 unsigned int sectorsize,
1477 int verbose)
1478{
1479 btp->bt_bsize = blocksize;
1480 btp->bt_sshift = ffs(sectorsize) - 1;
1481 btp->bt_smask = sectorsize - 1;
1482
1483 if (set_blocksize(btp->bt_bdev, sectorsize)) {
1484 xfs_warn(btp->bt_mount,
1485 "Cannot set_blocksize to %u on device %s\n",
1486 sectorsize, xfs_buf_target_name(btp));
1487 return EINVAL;
1488 }
1489
1490 return 0;
1491}
1492
1493/*
1494 * When allocating the initial buffer target we have not yet
1495 * read in the superblock, so don't know what sized sectors
1496 * are being used is at this early stage. Play safe.
1497 */
1498STATIC int
1499xfs_setsize_buftarg_early(
1500 xfs_buftarg_t *btp,
1501 struct block_device *bdev)
1502{
1503 return xfs_setsize_buftarg_flags(btp,
1504 PAGE_SIZE, bdev_logical_block_size(bdev), 0);
1505}
1506
1507int
1508xfs_setsize_buftarg(
1509 xfs_buftarg_t *btp,
1510 unsigned int blocksize,
1511 unsigned int sectorsize)
1512{
1513 return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1);
1514}
1515
1516STATIC int
1517xfs_alloc_delwrite_queue(
1518 xfs_buftarg_t *btp,
1519 const char *fsname)
1520{
1521 INIT_LIST_HEAD(&btp->bt_delwrite_queue);
1522 spin_lock_init(&btp->bt_delwrite_lock);
1523 btp->bt_flags = 0;
1524 btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd/%s", fsname);
1525 if (IS_ERR(btp->bt_task))
1526 return PTR_ERR(btp->bt_task);
1527 return 0;
1528}
1529
1530xfs_buftarg_t *
1531xfs_alloc_buftarg(
1532 struct xfs_mount *mp,
1533 struct block_device *bdev,
1534 int external,
1535 const char *fsname)
1536{
1537 xfs_buftarg_t *btp;
1538
1539 btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
1540
1541 btp->bt_mount = mp;
1542 btp->bt_dev = bdev->bd_dev;
1543 btp->bt_bdev = bdev;
1544 btp->bt_bdi = blk_get_backing_dev_info(bdev);
1545 if (!btp->bt_bdi)
1546 goto error;
1547
1548 INIT_LIST_HEAD(&btp->bt_lru);
1549 spin_lock_init(&btp->bt_lru_lock);
1550 if (xfs_setsize_buftarg_early(btp, bdev))
1551 goto error;
1552 if (xfs_alloc_delwrite_queue(btp, fsname))
1553 goto error;
1554 btp->bt_shrinker.shrink = xfs_buftarg_shrink;
1555 btp->bt_shrinker.seeks = DEFAULT_SEEKS;
1556 register_shrinker(&btp->bt_shrinker);
1557 return btp;
1558
1559error:
1560 kmem_free(btp);
1561 return NULL;
1562}
1563
1564
1565/*
1566 * Delayed write buffer handling
1567 */
1568STATIC void
1569xfs_buf_delwri_queue(
1570 xfs_buf_t *bp,
1571 int unlock)
1572{
1573 struct list_head *dwq = &bp->b_target->bt_delwrite_queue;
1574 spinlock_t *dwlk = &bp->b_target->bt_delwrite_lock;
1575
1576 trace_xfs_buf_delwri_queue(bp, _RET_IP_);
1577
1578 ASSERT((bp->b_flags&(XBF_DELWRI|XBF_ASYNC)) == (XBF_DELWRI|XBF_ASYNC));
1579
1580 spin_lock(dwlk);
1581 /* If already in the queue, dequeue and place at tail */
1582 if (!list_empty(&bp->b_list)) {
1583 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1584 if (unlock)
1585 atomic_dec(&bp->b_hold);
1586 list_del(&bp->b_list);
1587 }
1588
1589 if (list_empty(dwq)) {
1590 /* start xfsbufd as it is about to have something to do */
1591 wake_up_process(bp->b_target->bt_task);
1592 }
1593
1594 bp->b_flags |= _XBF_DELWRI_Q;
1595 list_add_tail(&bp->b_list, dwq);
1596 bp->b_queuetime = jiffies;
1597 spin_unlock(dwlk);
1598
1599 if (unlock)
1600 xfs_buf_unlock(bp);
1601}
1602
1603void
1604xfs_buf_delwri_dequeue(
1605 xfs_buf_t *bp)
1606{
1607 spinlock_t *dwlk = &bp->b_target->bt_delwrite_lock;
1608 int dequeued = 0;
1609
1610 spin_lock(dwlk);
1611 if ((bp->b_flags & XBF_DELWRI) && !list_empty(&bp->b_list)) {
1612 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1613 list_del_init(&bp->b_list);
1614 dequeued = 1;
1615 }
1616 bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
1617 spin_unlock(dwlk);
1618
1619 if (dequeued)
1620 xfs_buf_rele(bp);
1621
1622 trace_xfs_buf_delwri_dequeue(bp, _RET_IP_);
1623}
1624
1625/*
1626 * If a delwri buffer needs to be pushed before it has aged out, then promote
1627 * it to the head of the delwri queue so that it will be flushed on the next
1628 * xfsbufd run. We do this by resetting the queuetime of the buffer to be older
1629 * than the age currently needed to flush the buffer. Hence the next time the
1630 * xfsbufd sees it is guaranteed to be considered old enough to flush.
1631 */
1632void
1633xfs_buf_delwri_promote(
1634 struct xfs_buf *bp)
1635{
1636 struct xfs_buftarg *btp = bp->b_target;
1637 long age = xfs_buf_age_centisecs * msecs_to_jiffies(10) + 1;
1638
1639 ASSERT(bp->b_flags & XBF_DELWRI);
1640 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1641
1642 /*
1643 * Check the buffer age before locking the delayed write queue as we
1644 * don't need to promote buffers that are already past the flush age.
1645 */
1646 if (bp->b_queuetime < jiffies - age)
1647 return;
1648 bp->b_queuetime = jiffies - age;
1649 spin_lock(&btp->bt_delwrite_lock);
1650 list_move(&bp->b_list, &btp->bt_delwrite_queue);
1651 spin_unlock(&btp->bt_delwrite_lock);
1652}
1653
1654STATIC void
1655xfs_buf_runall_queues(
1656 struct workqueue_struct *queue)
1657{
1658 flush_workqueue(queue);
1659}
1660
1661/*
1662 * Move as many buffers as specified to the supplied list
1663 * idicating if we skipped any buffers to prevent deadlocks.
1664 */
1665STATIC int
1666xfs_buf_delwri_split(
1667 xfs_buftarg_t *target,
1668 struct list_head *list,
1669 unsigned long age)
1670{
1671 xfs_buf_t *bp, *n;
1672 struct list_head *dwq = &target->bt_delwrite_queue;
1673 spinlock_t *dwlk = &target->bt_delwrite_lock;
1674 int skipped = 0;
1675 int force;
1676
1677 force = test_and_clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1678 INIT_LIST_HEAD(list);
1679 spin_lock(dwlk);
1680 list_for_each_entry_safe(bp, n, dwq, b_list) {
1681 ASSERT(bp->b_flags & XBF_DELWRI);
1682
1683 if (!xfs_buf_ispinned(bp) && xfs_buf_trylock(bp)) {
1684 if (!force &&
1685 time_before(jiffies, bp->b_queuetime + age)) {
1686 xfs_buf_unlock(bp);
1687 break;
1688 }
1689
1690 bp->b_flags &= ~(XBF_DELWRI | _XBF_DELWRI_Q);
1691 bp->b_flags |= XBF_WRITE;
1692 list_move_tail(&bp->b_list, list);
1693 trace_xfs_buf_delwri_split(bp, _RET_IP_);
1694 } else
1695 skipped++;
1696 }
1697 spin_unlock(dwlk);
1698
1699 return skipped;
1700
1701}
1702
1703/*
1704 * Compare function is more complex than it needs to be because
1705 * the return value is only 32 bits and we are doing comparisons
1706 * on 64 bit values
1707 */
1708static int
1709xfs_buf_cmp(
1710 void *priv,
1711 struct list_head *a,
1712 struct list_head *b)
1713{
1714 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
1715 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
1716 xfs_daddr_t diff;
1717
1718 diff = ap->b_bn - bp->b_bn;
1719 if (diff < 0)
1720 return -1;
1721 if (diff > 0)
1722 return 1;
1723 return 0;
1724}
1725
1726STATIC int
1727xfsbufd(
1728 void *data)
1729{
1730 xfs_buftarg_t *target = (xfs_buftarg_t *)data;
1731
1732 current->flags |= PF_MEMALLOC;
1733
1734 set_freezable();
1735
1736 do {
1737 long age = xfs_buf_age_centisecs * msecs_to_jiffies(10);
1738 long tout = xfs_buf_timer_centisecs * msecs_to_jiffies(10);
1739 struct list_head tmp;
1740 struct blk_plug plug;
1741
1742 if (unlikely(freezing(current))) {
1743 set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1744 refrigerator();
1745 } else {
1746 clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1747 }
1748
1749 /* sleep for a long time if there is nothing to do. */
1750 if (list_empty(&target->bt_delwrite_queue))
1751 tout = MAX_SCHEDULE_TIMEOUT;
1752 schedule_timeout_interruptible(tout);
1753
1754 xfs_buf_delwri_split(target, &tmp, age);
1755 list_sort(NULL, &tmp, xfs_buf_cmp);
1756
1757 blk_start_plug(&plug);
1758 while (!list_empty(&tmp)) {
1759 struct xfs_buf *bp;
1760 bp = list_first_entry(&tmp, struct xfs_buf, b_list);
1761 list_del_init(&bp->b_list);
1762 xfs_bdstrat_cb(bp);
1763 }
1764 blk_finish_plug(&plug);
1765 } while (!kthread_should_stop());
1766
1767 return 0;
1768}
1769
1770/*
1771 * Go through all incore buffers, and release buffers if they belong to
1772 * the given device. This is used in filesystem error handling to
1773 * preserve the consistency of its metadata.
1774 */
1775int
1776xfs_flush_buftarg(
1777 xfs_buftarg_t *target,
1778 int wait)
1779{
1780 xfs_buf_t *bp;
1781 int pincount = 0;
1782 LIST_HEAD(tmp_list);
1783 LIST_HEAD(wait_list);
1784 struct blk_plug plug;
1785
1786 xfs_buf_runall_queues(xfsconvertd_workqueue);
1787 xfs_buf_runall_queues(xfsdatad_workqueue);
1788 xfs_buf_runall_queues(xfslogd_workqueue);
1789
1790 set_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1791 pincount = xfs_buf_delwri_split(target, &tmp_list, 0);
1792
1793 /*
1794 * Dropped the delayed write list lock, now walk the temporary list.
1795 * All I/O is issued async and then if we need to wait for completion
1796 * we do that after issuing all the IO.
1797 */
1798 list_sort(NULL, &tmp_list, xfs_buf_cmp);
1799
1800 blk_start_plug(&plug);
1801 while (!list_empty(&tmp_list)) {
1802 bp = list_first_entry(&tmp_list, struct xfs_buf, b_list);
1803 ASSERT(target == bp->b_target);
1804 list_del_init(&bp->b_list);
1805 if (wait) {
1806 bp->b_flags &= ~XBF_ASYNC;
1807 list_add(&bp->b_list, &wait_list);
1808 }
1809 xfs_bdstrat_cb(bp);
1810 }
1811 blk_finish_plug(&plug);
1812
1813 if (wait) {
1814 /* Wait for IO to complete. */
1815 while (!list_empty(&wait_list)) {
1816 bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
1817
1818 list_del_init(&bp->b_list);
1819 xfs_buf_iowait(bp);
1820 xfs_buf_relse(bp);
1821 }
1822 }
1823
1824 return pincount;
1825}
1826
1827int __init
1828xfs_buf_init(void)
1829{
1830 xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
1831 KM_ZONE_HWALIGN, NULL);
1832 if (!xfs_buf_zone)
1833 goto out;
1834
1835 xfslogd_workqueue = alloc_workqueue("xfslogd",
1836 WQ_MEM_RECLAIM | WQ_HIGHPRI, 1);
1837 if (!xfslogd_workqueue)
1838 goto out_free_buf_zone;
1839
1840 xfsdatad_workqueue = alloc_workqueue("xfsdatad", WQ_MEM_RECLAIM, 1);
1841 if (!xfsdatad_workqueue)
1842 goto out_destroy_xfslogd_workqueue;
1843
1844 xfsconvertd_workqueue = alloc_workqueue("xfsconvertd",
1845 WQ_MEM_RECLAIM, 1);
1846 if (!xfsconvertd_workqueue)
1847 goto out_destroy_xfsdatad_workqueue;
1848
1849 return 0;
1850
1851 out_destroy_xfsdatad_workqueue:
1852 destroy_workqueue(xfsdatad_workqueue);
1853 out_destroy_xfslogd_workqueue:
1854 destroy_workqueue(xfslogd_workqueue);
1855 out_free_buf_zone:
1856 kmem_zone_destroy(xfs_buf_zone);
1857 out:
1858 return -ENOMEM;
1859}
1860
1861void
1862xfs_buf_terminate(void)
1863{
1864 destroy_workqueue(xfsconvertd_workqueue);
1865 destroy_workqueue(xfsdatad_workqueue);
1866 destroy_workqueue(xfslogd_workqueue);
1867 kmem_zone_destroy(xfs_buf_zone);
1868}
1869
1870#ifdef CONFIG_KDB_MODULES
1871struct list_head *
1872xfs_get_buftarg_list(void)
1873{
1874 return &xfs_buftarg_list;
1875}
1876#endif
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-18 11:07:25 -0500