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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
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
4 * All Rights Reserved.
5 */
6#include "xfs.h"
7#include <linux/backing-dev.h>
8#include <linux/dax.h>
9
10#include "xfs_shared.h"
11#include "xfs_format.h"
12#include "xfs_log_format.h"
13#include "xfs_trans_resv.h"
14#include "xfs_mount.h"
15#include "xfs_trace.h"
16#include "xfs_log.h"
17#include "xfs_log_recover.h"
18#include "xfs_log_priv.h"
19#include "xfs_trans.h"
20#include "xfs_buf_item.h"
21#include "xfs_errortag.h"
22#include "xfs_error.h"
23#include "xfs_ag.h"
24
25struct kmem_cache *xfs_buf_cache;
26
27/*
28 * Locking orders
29 *
30 * xfs_buf_ioacct_inc:
31 * xfs_buf_ioacct_dec:
32 * b_sema (caller holds)
33 * b_lock
34 *
35 * xfs_buf_stale:
36 * b_sema (caller holds)
37 * b_lock
38 * lru_lock
39 *
40 * xfs_buf_rele:
41 * b_lock
42 * pag_buf_lock
43 * lru_lock
44 *
45 * xfs_buftarg_drain_rele
46 * lru_lock
47 * b_lock (trylock due to inversion)
48 *
49 * xfs_buftarg_isolate
50 * lru_lock
51 * b_lock (trylock due to inversion)
52 */
53
54static int __xfs_buf_submit(struct xfs_buf *bp, bool wait);
55
56static inline int
57xfs_buf_submit(
58 struct xfs_buf *bp)
59{
60 return __xfs_buf_submit(bp, !(bp->b_flags & XBF_ASYNC));
61}
62
63static inline int
64xfs_buf_is_vmapped(
65 struct xfs_buf *bp)
66{
67 /*
68 * Return true if the buffer is vmapped.
69 *
70 * b_addr is null if the buffer is not mapped, but the code is clever
71 * enough to know it doesn't have to map a single page, so the check has
72 * to be both for b_addr and bp->b_page_count > 1.
73 */
74 return bp->b_addr && bp->b_page_count > 1;
75}
76
77static inline int
78xfs_buf_vmap_len(
79 struct xfs_buf *bp)
80{
81 return (bp->b_page_count * PAGE_SIZE);
82}
83
84/*
85 * Bump the I/O in flight count on the buftarg if we haven't yet done so for
86 * this buffer. The count is incremented once per buffer (per hold cycle)
87 * because the corresponding decrement is deferred to buffer release. Buffers
88 * can undergo I/O multiple times in a hold-release cycle and per buffer I/O
89 * tracking adds unnecessary overhead. This is used for sychronization purposes
90 * with unmount (see xfs_buftarg_drain()), so all we really need is a count of
91 * in-flight buffers.
92 *
93 * Buffers that are never released (e.g., superblock, iclog buffers) must set
94 * the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count
95 * never reaches zero and unmount hangs indefinitely.
96 */
97static inline void
98xfs_buf_ioacct_inc(
99 struct xfs_buf *bp)
100{
101 if (bp->b_flags & XBF_NO_IOACCT)
102 return;
103
104 ASSERT(bp->b_flags & XBF_ASYNC);
105 spin_lock(&bp->b_lock);
106 if (!(bp->b_state & XFS_BSTATE_IN_FLIGHT)) {
107 bp->b_state |= XFS_BSTATE_IN_FLIGHT;
108 percpu_counter_inc(&bp->b_target->bt_io_count);
109 }
110 spin_unlock(&bp->b_lock);
111}
112
113/*
114 * Clear the in-flight state on a buffer about to be released to the LRU or
115 * freed and unaccount from the buftarg.
116 */
117static inline void
118__xfs_buf_ioacct_dec(
119 struct xfs_buf *bp)
120{
121 lockdep_assert_held(&bp->b_lock);
122
123 if (bp->b_state & XFS_BSTATE_IN_FLIGHT) {
124 bp->b_state &= ~XFS_BSTATE_IN_FLIGHT;
125 percpu_counter_dec(&bp->b_target->bt_io_count);
126 }
127}
128
129static inline void
130xfs_buf_ioacct_dec(
131 struct xfs_buf *bp)
132{
133 spin_lock(&bp->b_lock);
134 __xfs_buf_ioacct_dec(bp);
135 spin_unlock(&bp->b_lock);
136}
137
138/*
139 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
140 * b_lru_ref count so that the buffer is freed immediately when the buffer
141 * reference count falls to zero. If the buffer is already on the LRU, we need
142 * to remove the reference that LRU holds on the buffer.
143 *
144 * This prevents build-up of stale buffers on the LRU.
145 */
146void
147xfs_buf_stale(
148 struct xfs_buf *bp)
149{
150 ASSERT(xfs_buf_islocked(bp));
151
152 bp->b_flags |= XBF_STALE;
153
154 /*
155 * Clear the delwri status so that a delwri queue walker will not
156 * flush this buffer to disk now that it is stale. The delwri queue has
157 * a reference to the buffer, so this is safe to do.
158 */
159 bp->b_flags &= ~_XBF_DELWRI_Q;
160
161 /*
162 * Once the buffer is marked stale and unlocked, a subsequent lookup
163 * could reset b_flags. There is no guarantee that the buffer is
164 * unaccounted (released to LRU) before that occurs. Drop in-flight
165 * status now to preserve accounting consistency.
166 */
167 spin_lock(&bp->b_lock);
168 __xfs_buf_ioacct_dec(bp);
169
170 atomic_set(&bp->b_lru_ref, 0);
171 if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
172 (list_lru_del_obj(&bp->b_target->bt_lru, &bp->b_lru)))
173 atomic_dec(&bp->b_hold);
174
175 ASSERT(atomic_read(&bp->b_hold) >= 1);
176 spin_unlock(&bp->b_lock);
177}
178
179static int
180xfs_buf_get_maps(
181 struct xfs_buf *bp,
182 int map_count)
183{
184 ASSERT(bp->b_maps == NULL);
185 bp->b_map_count = map_count;
186
187 if (map_count == 1) {
188 bp->b_maps = &bp->__b_map;
189 return 0;
190 }
191
192 bp->b_maps = kmem_zalloc(map_count * sizeof(struct xfs_buf_map),
193 KM_NOFS);
194 if (!bp->b_maps)
195 return -ENOMEM;
196 return 0;
197}
198
199/*
200 * Frees b_pages if it was allocated.
201 */
202static void
203xfs_buf_free_maps(
204 struct xfs_buf *bp)
205{
206 if (bp->b_maps != &bp->__b_map) {
207 kmem_free(bp->b_maps);
208 bp->b_maps = NULL;
209 }
210}
211
212static int
213_xfs_buf_alloc(
214 struct xfs_buftarg *target,
215 struct xfs_buf_map *map,
216 int nmaps,
217 xfs_buf_flags_t flags,
218 struct xfs_buf **bpp)
219{
220 struct xfs_buf *bp;
221 int error;
222 int i;
223
224 *bpp = NULL;
225 bp = kmem_cache_zalloc(xfs_buf_cache, GFP_NOFS | __GFP_NOFAIL);
226
227 /*
228 * We don't want certain flags to appear in b_flags unless they are
229 * specifically set by later operations on the buffer.
230 */
231 flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
232
233 atomic_set(&bp->b_hold, 1);
234 atomic_set(&bp->b_lru_ref, 1);
235 init_completion(&bp->b_iowait);
236 INIT_LIST_HEAD(&bp->b_lru);
237 INIT_LIST_HEAD(&bp->b_list);
238 INIT_LIST_HEAD(&bp->b_li_list);
239 sema_init(&bp->b_sema, 0); /* held, no waiters */
240 spin_lock_init(&bp->b_lock);
241 bp->b_target = target;
242 bp->b_mount = target->bt_mount;
243 bp->b_flags = flags;
244
245 /*
246 * Set length and io_length to the same value initially.
247 * I/O routines should use io_length, which will be the same in
248 * most cases but may be reset (e.g. XFS recovery).
249 */
250 error = xfs_buf_get_maps(bp, nmaps);
251 if (error) {
252 kmem_cache_free(xfs_buf_cache, bp);
253 return error;
254 }
255
256 bp->b_rhash_key = map[0].bm_bn;
257 bp->b_length = 0;
258 for (i = 0; i < nmaps; i++) {
259 bp->b_maps[i].bm_bn = map[i].bm_bn;
260 bp->b_maps[i].bm_len = map[i].bm_len;
261 bp->b_length += map[i].bm_len;
262 }
263
264 atomic_set(&bp->b_pin_count, 0);
265 init_waitqueue_head(&bp->b_waiters);
266
267 XFS_STATS_INC(bp->b_mount, xb_create);
268 trace_xfs_buf_init(bp, _RET_IP_);
269
270 *bpp = bp;
271 return 0;
272}
273
274static void
275xfs_buf_free_pages(
276 struct xfs_buf *bp)
277{
278 uint i;
279
280 ASSERT(bp->b_flags & _XBF_PAGES);
281
282 if (xfs_buf_is_vmapped(bp))
283 vm_unmap_ram(bp->b_addr, bp->b_page_count);
284
285 for (i = 0; i < bp->b_page_count; i++) {
286 if (bp->b_pages[i])
287 __free_page(bp->b_pages[i]);
288 }
289 mm_account_reclaimed_pages(bp->b_page_count);
290
291 if (bp->b_pages != bp->b_page_array)
292 kmem_free(bp->b_pages);
293 bp->b_pages = NULL;
294 bp->b_flags &= ~_XBF_PAGES;
295}
296
297static void
298xfs_buf_free_callback(
299 struct callback_head *cb)
300{
301 struct xfs_buf *bp = container_of(cb, struct xfs_buf, b_rcu);
302
303 xfs_buf_free_maps(bp);
304 kmem_cache_free(xfs_buf_cache, bp);
305}
306
307static void
308xfs_buf_free(
309 struct xfs_buf *bp)
310{
311 trace_xfs_buf_free(bp, _RET_IP_);
312
313 ASSERT(list_empty(&bp->b_lru));
314
315 if (bp->b_flags & _XBF_PAGES)
316 xfs_buf_free_pages(bp);
317 else if (bp->b_flags & _XBF_KMEM)
318 kmem_free(bp->b_addr);
319
320 call_rcu(&bp->b_rcu, xfs_buf_free_callback);
321}
322
323static int
324xfs_buf_alloc_kmem(
325 struct xfs_buf *bp,
326 xfs_buf_flags_t flags)
327{
328 xfs_km_flags_t kmflag_mask = KM_NOFS;
329 size_t size = BBTOB(bp->b_length);
330
331 /* Assure zeroed buffer for non-read cases. */
332 if (!(flags & XBF_READ))
333 kmflag_mask |= KM_ZERO;
334
335 bp->b_addr = kmem_alloc(size, kmflag_mask);
336 if (!bp->b_addr)
337 return -ENOMEM;
338
339 if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
340 ((unsigned long)bp->b_addr & PAGE_MASK)) {
341 /* b_addr spans two pages - use alloc_page instead */
342 kmem_free(bp->b_addr);
343 bp->b_addr = NULL;
344 return -ENOMEM;
345 }
346 bp->b_offset = offset_in_page(bp->b_addr);
347 bp->b_pages = bp->b_page_array;
348 bp->b_pages[0] = kmem_to_page(bp->b_addr);
349 bp->b_page_count = 1;
350 bp->b_flags |= _XBF_KMEM;
351 return 0;
352}
353
354static int
355xfs_buf_alloc_pages(
356 struct xfs_buf *bp,
357 xfs_buf_flags_t flags)
358{
359 gfp_t gfp_mask = __GFP_NOWARN;
360 long filled = 0;
361
362 if (flags & XBF_READ_AHEAD)
363 gfp_mask |= __GFP_NORETRY;
364 else
365 gfp_mask |= GFP_NOFS;
366
367 /* Make sure that we have a page list */
368 bp->b_page_count = DIV_ROUND_UP(BBTOB(bp->b_length), PAGE_SIZE);
369 if (bp->b_page_count <= XB_PAGES) {
370 bp->b_pages = bp->b_page_array;
371 } else {
372 bp->b_pages = kzalloc(sizeof(struct page *) * bp->b_page_count,
373 gfp_mask);
374 if (!bp->b_pages)
375 return -ENOMEM;
376 }
377 bp->b_flags |= _XBF_PAGES;
378
379 /* Assure zeroed buffer for non-read cases. */
380 if (!(flags & XBF_READ))
381 gfp_mask |= __GFP_ZERO;
382
383 /*
384 * Bulk filling of pages can take multiple calls. Not filling the entire
385 * array is not an allocation failure, so don't back off if we get at
386 * least one extra page.
387 */
388 for (;;) {
389 long last = filled;
390
391 filled = alloc_pages_bulk_array(gfp_mask, bp->b_page_count,
392 bp->b_pages);
393 if (filled == bp->b_page_count) {
394 XFS_STATS_INC(bp->b_mount, xb_page_found);
395 break;
396 }
397
398 if (filled != last)
399 continue;
400
401 if (flags & XBF_READ_AHEAD) {
402 xfs_buf_free_pages(bp);
403 return -ENOMEM;
404 }
405
406 XFS_STATS_INC(bp->b_mount, xb_page_retries);
407 memalloc_retry_wait(gfp_mask);
408 }
409 return 0;
410}
411
412/*
413 * Map buffer into kernel address-space if necessary.
414 */
415STATIC int
416_xfs_buf_map_pages(
417 struct xfs_buf *bp,
418 xfs_buf_flags_t flags)
419{
420 ASSERT(bp->b_flags & _XBF_PAGES);
421 if (bp->b_page_count == 1) {
422 /* A single page buffer is always mappable */
423 bp->b_addr = page_address(bp->b_pages[0]);
424 } else if (flags & XBF_UNMAPPED) {
425 bp->b_addr = NULL;
426 } else {
427 int retried = 0;
428 unsigned nofs_flag;
429
430 /*
431 * vm_map_ram() will allocate auxiliary structures (e.g.
432 * pagetables) with GFP_KERNEL, yet we are likely to be under
433 * GFP_NOFS context here. Hence we need to tell memory reclaim
434 * that we are in such a context via PF_MEMALLOC_NOFS to prevent
435 * memory reclaim re-entering the filesystem here and
436 * potentially deadlocking.
437 */
438 nofs_flag = memalloc_nofs_save();
439 do {
440 bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
441 -1);
442 if (bp->b_addr)
443 break;
444 vm_unmap_aliases();
445 } while (retried++ <= 1);
446 memalloc_nofs_restore(nofs_flag);
447
448 if (!bp->b_addr)
449 return -ENOMEM;
450 }
451
452 return 0;
453}
454
455/*
456 * Finding and Reading Buffers
457 */
458static int
459_xfs_buf_obj_cmp(
460 struct rhashtable_compare_arg *arg,
461 const void *obj)
462{
463 const struct xfs_buf_map *map = arg->key;
464 const struct xfs_buf *bp = obj;
465
466 /*
467 * The key hashing in the lookup path depends on the key being the
468 * first element of the compare_arg, make sure to assert this.
469 */
470 BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
471
472 if (bp->b_rhash_key != map->bm_bn)
473 return 1;
474
475 if (unlikely(bp->b_length != map->bm_len)) {
476 /*
477 * found a block number match. If the range doesn't
478 * match, the only way this is allowed is if the buffer
479 * in the cache is stale and the transaction that made
480 * it stale has not yet committed. i.e. we are
481 * reallocating a busy extent. Skip this buffer and
482 * continue searching for an exact match.
483 */
484 if (!(map->bm_flags & XBM_LIVESCAN))
485 ASSERT(bp->b_flags & XBF_STALE);
486 return 1;
487 }
488 return 0;
489}
490
491static const struct rhashtable_params xfs_buf_hash_params = {
492 .min_size = 32, /* empty AGs have minimal footprint */
493 .nelem_hint = 16,
494 .key_len = sizeof(xfs_daddr_t),
495 .key_offset = offsetof(struct xfs_buf, b_rhash_key),
496 .head_offset = offsetof(struct xfs_buf, b_rhash_head),
497 .automatic_shrinking = true,
498 .obj_cmpfn = _xfs_buf_obj_cmp,
499};
500
501int
502xfs_buf_hash_init(
503 struct xfs_perag *pag)
504{
505 spin_lock_init(&pag->pag_buf_lock);
506 return rhashtable_init(&pag->pag_buf_hash, &xfs_buf_hash_params);
507}
508
509void
510xfs_buf_hash_destroy(
511 struct xfs_perag *pag)
512{
513 rhashtable_destroy(&pag->pag_buf_hash);
514}
515
516static int
517xfs_buf_map_verify(
518 struct xfs_buftarg *btp,
519 struct xfs_buf_map *map)
520{
521 xfs_daddr_t eofs;
522
523 /* Check for IOs smaller than the sector size / not sector aligned */
524 ASSERT(!(BBTOB(map->bm_len) < btp->bt_meta_sectorsize));
525 ASSERT(!(BBTOB(map->bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
526
527 /*
528 * Corrupted block numbers can get through to here, unfortunately, so we
529 * have to check that the buffer falls within the filesystem bounds.
530 */
531 eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
532 if (map->bm_bn < 0 || map->bm_bn >= eofs) {
533 xfs_alert(btp->bt_mount,
534 "%s: daddr 0x%llx out of range, EOFS 0x%llx",
535 __func__, map->bm_bn, eofs);
536 WARN_ON(1);
537 return -EFSCORRUPTED;
538 }
539 return 0;
540}
541
542static int
543xfs_buf_find_lock(
544 struct xfs_buf *bp,
545 xfs_buf_flags_t flags)
546{
547 if (flags & XBF_TRYLOCK) {
548 if (!xfs_buf_trylock(bp)) {
549 XFS_STATS_INC(bp->b_mount, xb_busy_locked);
550 return -EAGAIN;
551 }
552 } else {
553 xfs_buf_lock(bp);
554 XFS_STATS_INC(bp->b_mount, xb_get_locked_waited);
555 }
556
557 /*
558 * if the buffer is stale, clear all the external state associated with
559 * it. We need to keep flags such as how we allocated the buffer memory
560 * intact here.
561 */
562 if (bp->b_flags & XBF_STALE) {
563 if (flags & XBF_LIVESCAN) {
564 xfs_buf_unlock(bp);
565 return -ENOENT;
566 }
567 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
568 bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
569 bp->b_ops = NULL;
570 }
571 return 0;
572}
573
574static inline int
575xfs_buf_lookup(
576 struct xfs_perag *pag,
577 struct xfs_buf_map *map,
578 xfs_buf_flags_t flags,
579 struct xfs_buf **bpp)
580{
581 struct xfs_buf *bp;
582 int error;
583
584 rcu_read_lock();
585 bp = rhashtable_lookup(&pag->pag_buf_hash, map, xfs_buf_hash_params);
586 if (!bp || !atomic_inc_not_zero(&bp->b_hold)) {
587 rcu_read_unlock();
588 return -ENOENT;
589 }
590 rcu_read_unlock();
591
592 error = xfs_buf_find_lock(bp, flags);
593 if (error) {
594 xfs_buf_rele(bp);
595 return error;
596 }
597
598 trace_xfs_buf_find(bp, flags, _RET_IP_);
599 *bpp = bp;
600 return 0;
601}
602
603/*
604 * Insert the new_bp into the hash table. This consumes the perag reference
605 * taken for the lookup regardless of the result of the insert.
606 */
607static int
608xfs_buf_find_insert(
609 struct xfs_buftarg *btp,
610 struct xfs_perag *pag,
611 struct xfs_buf_map *cmap,
612 struct xfs_buf_map *map,
613 int nmaps,
614 xfs_buf_flags_t flags,
615 struct xfs_buf **bpp)
616{
617 struct xfs_buf *new_bp;
618 struct xfs_buf *bp;
619 int error;
620
621 error = _xfs_buf_alloc(btp, map, nmaps, flags, &new_bp);
622 if (error)
623 goto out_drop_pag;
624
625 /*
626 * For buffers that fit entirely within a single page, first attempt to
627 * allocate the memory from the heap to minimise memory usage. If we
628 * can't get heap memory for these small buffers, we fall back to using
629 * the page allocator.
630 */
631 if (BBTOB(new_bp->b_length) >= PAGE_SIZE ||
632 xfs_buf_alloc_kmem(new_bp, flags) < 0) {
633 error = xfs_buf_alloc_pages(new_bp, flags);
634 if (error)
635 goto out_free_buf;
636 }
637
638 spin_lock(&pag->pag_buf_lock);
639 bp = rhashtable_lookup_get_insert_fast(&pag->pag_buf_hash,
640 &new_bp->b_rhash_head, xfs_buf_hash_params);
641 if (IS_ERR(bp)) {
642 error = PTR_ERR(bp);
643 spin_unlock(&pag->pag_buf_lock);
644 goto out_free_buf;
645 }
646 if (bp) {
647 /* found an existing buffer */
648 atomic_inc(&bp->b_hold);
649 spin_unlock(&pag->pag_buf_lock);
650 error = xfs_buf_find_lock(bp, flags);
651 if (error)
652 xfs_buf_rele(bp);
653 else
654 *bpp = bp;
655 goto out_free_buf;
656 }
657
658 /* The new buffer keeps the perag reference until it is freed. */
659 new_bp->b_pag = pag;
660 spin_unlock(&pag->pag_buf_lock);
661 *bpp = new_bp;
662 return 0;
663
664out_free_buf:
665 xfs_buf_free(new_bp);
666out_drop_pag:
667 xfs_perag_put(pag);
668 return error;
669}
670
671/*
672 * Assembles a buffer covering the specified range. The code is optimised for
673 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
674 * more hits than misses.
675 */
676int
677xfs_buf_get_map(
678 struct xfs_buftarg *btp,
679 struct xfs_buf_map *map,
680 int nmaps,
681 xfs_buf_flags_t flags,
682 struct xfs_buf **bpp)
683{
684 struct xfs_perag *pag;
685 struct xfs_buf *bp = NULL;
686 struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
687 int error;
688 int i;
689
690 if (flags & XBF_LIVESCAN)
691 cmap.bm_flags |= XBM_LIVESCAN;
692 for (i = 0; i < nmaps; i++)
693 cmap.bm_len += map[i].bm_len;
694
695 error = xfs_buf_map_verify(btp, &cmap);
696 if (error)
697 return error;
698
699 pag = xfs_perag_get(btp->bt_mount,
700 xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
701
702 error = xfs_buf_lookup(pag, &cmap, flags, &bp);
703 if (error && error != -ENOENT)
704 goto out_put_perag;
705
706 /* cache hits always outnumber misses by at least 10:1 */
707 if (unlikely(!bp)) {
708 XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
709
710 if (flags & XBF_INCORE)
711 goto out_put_perag;
712
713 /* xfs_buf_find_insert() consumes the perag reference. */
714 error = xfs_buf_find_insert(btp, pag, &cmap, map, nmaps,
715 flags, &bp);
716 if (error)
717 return error;
718 } else {
719 XFS_STATS_INC(btp->bt_mount, xb_get_locked);
720 xfs_perag_put(pag);
721 }
722
723 /* We do not hold a perag reference anymore. */
724 if (!bp->b_addr) {
725 error = _xfs_buf_map_pages(bp, flags);
726 if (unlikely(error)) {
727 xfs_warn_ratelimited(btp->bt_mount,
728 "%s: failed to map %u pages", __func__,
729 bp->b_page_count);
730 xfs_buf_relse(bp);
731 return error;
732 }
733 }
734
735 /*
736 * Clear b_error if this is a lookup from a caller that doesn't expect
737 * valid data to be found in the buffer.
738 */
739 if (!(flags & XBF_READ))
740 xfs_buf_ioerror(bp, 0);
741
742 XFS_STATS_INC(btp->bt_mount, xb_get);
743 trace_xfs_buf_get(bp, flags, _RET_IP_);
744 *bpp = bp;
745 return 0;
746
747out_put_perag:
748 xfs_perag_put(pag);
749 return error;
750}
751
752int
753_xfs_buf_read(
754 struct xfs_buf *bp,
755 xfs_buf_flags_t flags)
756{
757 ASSERT(!(flags & XBF_WRITE));
758 ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
759
760 bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD | XBF_DONE);
761 bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
762
763 return xfs_buf_submit(bp);
764}
765
766/*
767 * Reverify a buffer found in cache without an attached ->b_ops.
768 *
769 * If the caller passed an ops structure and the buffer doesn't have ops
770 * assigned, set the ops and use it to verify the contents. If verification
771 * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
772 * already in XBF_DONE state on entry.
773 *
774 * Under normal operations, every in-core buffer is verified on read I/O
775 * completion. There are two scenarios that can lead to in-core buffers without
776 * an assigned ->b_ops. The first is during log recovery of buffers on a V4
777 * filesystem, though these buffers are purged at the end of recovery. The
778 * other is online repair, which intentionally reads with a NULL buffer ops to
779 * run several verifiers across an in-core buffer in order to establish buffer
780 * type. If repair can't establish that, the buffer will be left in memory
781 * with NULL buffer ops.
782 */
783int
784xfs_buf_reverify(
785 struct xfs_buf *bp,
786 const struct xfs_buf_ops *ops)
787{
788 ASSERT(bp->b_flags & XBF_DONE);
789 ASSERT(bp->b_error == 0);
790
791 if (!ops || bp->b_ops)
792 return 0;
793
794 bp->b_ops = ops;
795 bp->b_ops->verify_read(bp);
796 if (bp->b_error)
797 bp->b_flags &= ~XBF_DONE;
798 return bp->b_error;
799}
800
801int
802xfs_buf_read_map(
803 struct xfs_buftarg *target,
804 struct xfs_buf_map *map,
805 int nmaps,
806 xfs_buf_flags_t flags,
807 struct xfs_buf **bpp,
808 const struct xfs_buf_ops *ops,
809 xfs_failaddr_t fa)
810{
811 struct xfs_buf *bp;
812 int error;
813
814 flags |= XBF_READ;
815 *bpp = NULL;
816
817 error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
818 if (error)
819 return error;
820
821 trace_xfs_buf_read(bp, flags, _RET_IP_);
822
823 if (!(bp->b_flags & XBF_DONE)) {
824 /* Initiate the buffer read and wait. */
825 XFS_STATS_INC(target->bt_mount, xb_get_read);
826 bp->b_ops = ops;
827 error = _xfs_buf_read(bp, flags);
828
829 /* Readahead iodone already dropped the buffer, so exit. */
830 if (flags & XBF_ASYNC)
831 return 0;
832 } else {
833 /* Buffer already read; all we need to do is check it. */
834 error = xfs_buf_reverify(bp, ops);
835
836 /* Readahead already finished; drop the buffer and exit. */
837 if (flags & XBF_ASYNC) {
838 xfs_buf_relse(bp);
839 return 0;
840 }
841
842 /* We do not want read in the flags */
843 bp->b_flags &= ~XBF_READ;
844 ASSERT(bp->b_ops != NULL || ops == NULL);
845 }
846
847 /*
848 * If we've had a read error, then the contents of the buffer are
849 * invalid and should not be used. To ensure that a followup read tries
850 * to pull the buffer from disk again, we clear the XBF_DONE flag and
851 * mark the buffer stale. This ensures that anyone who has a current
852 * reference to the buffer will interpret it's contents correctly and
853 * future cache lookups will also treat it as an empty, uninitialised
854 * buffer.
855 */
856 if (error) {
857 /*
858 * Check against log shutdown for error reporting because
859 * metadata writeback may require a read first and we need to
860 * report errors in metadata writeback until the log is shut
861 * down. High level transaction read functions already check
862 * against mount shutdown, anyway, so we only need to be
863 * concerned about low level IO interactions here.
864 */
865 if (!xlog_is_shutdown(target->bt_mount->m_log))
866 xfs_buf_ioerror_alert(bp, fa);
867
868 bp->b_flags &= ~XBF_DONE;
869 xfs_buf_stale(bp);
870 xfs_buf_relse(bp);
871
872 /* bad CRC means corrupted metadata */
873 if (error == -EFSBADCRC)
874 error = -EFSCORRUPTED;
875 return error;
876 }
877
878 *bpp = bp;
879 return 0;
880}
881
882/*
883 * If we are not low on memory then do the readahead in a deadlock
884 * safe manner.
885 */
886void
887xfs_buf_readahead_map(
888 struct xfs_buftarg *target,
889 struct xfs_buf_map *map,
890 int nmaps,
891 const struct xfs_buf_ops *ops)
892{
893 struct xfs_buf *bp;
894
895 xfs_buf_read_map(target, map, nmaps,
896 XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops,
897 __this_address);
898}
899
900/*
901 * Read an uncached buffer from disk. Allocates and returns a locked
902 * buffer containing the disk contents or nothing. Uncached buffers always have
903 * a cache index of XFS_BUF_DADDR_NULL so we can easily determine if the buffer
904 * is cached or uncached during fault diagnosis.
905 */
906int
907xfs_buf_read_uncached(
908 struct xfs_buftarg *target,
909 xfs_daddr_t daddr,
910 size_t numblks,
911 xfs_buf_flags_t flags,
912 struct xfs_buf **bpp,
913 const struct xfs_buf_ops *ops)
914{
915 struct xfs_buf *bp;
916 int error;
917
918 *bpp = NULL;
919
920 error = xfs_buf_get_uncached(target, numblks, flags, &bp);
921 if (error)
922 return error;
923
924 /* set up the buffer for a read IO */
925 ASSERT(bp->b_map_count == 1);
926 bp->b_rhash_key = XFS_BUF_DADDR_NULL;
927 bp->b_maps[0].bm_bn = daddr;
928 bp->b_flags |= XBF_READ;
929 bp->b_ops = ops;
930
931 xfs_buf_submit(bp);
932 if (bp->b_error) {
933 error = bp->b_error;
934 xfs_buf_relse(bp);
935 return error;
936 }
937
938 *bpp = bp;
939 return 0;
940}
941
942int
943xfs_buf_get_uncached(
944 struct xfs_buftarg *target,
945 size_t numblks,
946 xfs_buf_flags_t flags,
947 struct xfs_buf **bpp)
948{
949 int error;
950 struct xfs_buf *bp;
951 DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
952
953 *bpp = NULL;
954
955 /* flags might contain irrelevant bits, pass only what we care about */
956 error = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT, &bp);
957 if (error)
958 return error;
959
960 error = xfs_buf_alloc_pages(bp, flags);
961 if (error)
962 goto fail_free_buf;
963
964 error = _xfs_buf_map_pages(bp, 0);
965 if (unlikely(error)) {
966 xfs_warn(target->bt_mount,
967 "%s: failed to map pages", __func__);
968 goto fail_free_buf;
969 }
970
971 trace_xfs_buf_get_uncached(bp, _RET_IP_);
972 *bpp = bp;
973 return 0;
974
975fail_free_buf:
976 xfs_buf_free(bp);
977 return error;
978}
979
980/*
981 * Increment reference count on buffer, to hold the buffer concurrently
982 * with another thread which may release (free) the buffer asynchronously.
983 * Must hold the buffer already to call this function.
984 */
985void
986xfs_buf_hold(
987 struct xfs_buf *bp)
988{
989 trace_xfs_buf_hold(bp, _RET_IP_);
990 atomic_inc(&bp->b_hold);
991}
992
993/*
994 * Release a hold on the specified buffer. If the hold count is 1, the buffer is
995 * placed on LRU or freed (depending on b_lru_ref).
996 */
997void
998xfs_buf_rele(
999 struct xfs_buf *bp)
1000{
1001 struct xfs_perag *pag = bp->b_pag;
1002 bool release;
1003 bool freebuf = false;
1004
1005 trace_xfs_buf_rele(bp, _RET_IP_);
1006
1007 if (!pag) {
1008 ASSERT(list_empty(&bp->b_lru));
1009 if (atomic_dec_and_test(&bp->b_hold)) {
1010 xfs_buf_ioacct_dec(bp);
1011 xfs_buf_free(bp);
1012 }
1013 return;
1014 }
1015
1016 ASSERT(atomic_read(&bp->b_hold) > 0);
1017
1018 /*
1019 * We grab the b_lock here first to serialise racing xfs_buf_rele()
1020 * calls. The pag_buf_lock being taken on the last reference only
1021 * serialises against racing lookups in xfs_buf_find(). IOWs, the second
1022 * to last reference we drop here is not serialised against the last
1023 * reference until we take bp->b_lock. Hence if we don't grab b_lock
1024 * first, the last "release" reference can win the race to the lock and
1025 * free the buffer before the second-to-last reference is processed,
1026 * leading to a use-after-free scenario.
1027 */
1028 spin_lock(&bp->b_lock);
1029 release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock);
1030 if (!release) {
1031 /*
1032 * Drop the in-flight state if the buffer is already on the LRU
1033 * and it holds the only reference. This is racy because we
1034 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
1035 * ensures the decrement occurs only once per-buf.
1036 */
1037 if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))
1038 __xfs_buf_ioacct_dec(bp);
1039 goto out_unlock;
1040 }
1041
1042 /* the last reference has been dropped ... */
1043 __xfs_buf_ioacct_dec(bp);
1044 if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
1045 /*
1046 * If the buffer is added to the LRU take a new reference to the
1047 * buffer for the LRU and clear the (now stale) dispose list
1048 * state flag
1049 */
1050 if (list_lru_add_obj(&bp->b_target->bt_lru, &bp->b_lru)) {
1051 bp->b_state &= ~XFS_BSTATE_DISPOSE;
1052 atomic_inc(&bp->b_hold);
1053 }
1054 spin_unlock(&pag->pag_buf_lock);
1055 } else {
1056 /*
1057 * most of the time buffers will already be removed from the
1058 * LRU, so optimise that case by checking for the
1059 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1060 * was on was the disposal list
1061 */
1062 if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
1063 list_lru_del_obj(&bp->b_target->bt_lru, &bp->b_lru);
1064 } else {
1065 ASSERT(list_empty(&bp->b_lru));
1066 }
1067
1068 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1069 rhashtable_remove_fast(&pag->pag_buf_hash, &bp->b_rhash_head,
1070 xfs_buf_hash_params);
1071 spin_unlock(&pag->pag_buf_lock);
1072 xfs_perag_put(pag);
1073 freebuf = true;
1074 }
1075
1076out_unlock:
1077 spin_unlock(&bp->b_lock);
1078
1079 if (freebuf)
1080 xfs_buf_free(bp);
1081}
1082
1083
1084/*
1085 * Lock a buffer object, if it is not already locked.
1086 *
1087 * If we come across a stale, pinned, locked buffer, we know that we are
1088 * being asked to lock a buffer that has been reallocated. Because it is
1089 * pinned, we know that the log has not been pushed to disk and hence it
1090 * will still be locked. Rather than continuing to have trylock attempts
1091 * fail until someone else pushes the log, push it ourselves before
1092 * returning. This means that the xfsaild will not get stuck trying
1093 * to push on stale inode buffers.
1094 */
1095int
1096xfs_buf_trylock(
1097 struct xfs_buf *bp)
1098{
1099 int locked;
1100
1101 locked = down_trylock(&bp->b_sema) == 0;
1102 if (locked)
1103 trace_xfs_buf_trylock(bp, _RET_IP_);
1104 else
1105 trace_xfs_buf_trylock_fail(bp, _RET_IP_);
1106 return locked;
1107}
1108
1109/*
1110 * Lock a buffer object.
1111 *
1112 * If we come across a stale, pinned, locked buffer, we know that we
1113 * are being asked to lock a buffer that has been reallocated. Because
1114 * it is pinned, we know that the log has not been pushed to disk and
1115 * hence it will still be locked. Rather than sleeping until someone
1116 * else pushes the log, push it ourselves before trying to get the lock.
1117 */
1118void
1119xfs_buf_lock(
1120 struct xfs_buf *bp)
1121{
1122 trace_xfs_buf_lock(bp, _RET_IP_);
1123
1124 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
1125 xfs_log_force(bp->b_mount, 0);
1126 down(&bp->b_sema);
1127
1128 trace_xfs_buf_lock_done(bp, _RET_IP_);
1129}
1130
1131void
1132xfs_buf_unlock(
1133 struct xfs_buf *bp)
1134{
1135 ASSERT(xfs_buf_islocked(bp));
1136
1137 up(&bp->b_sema);
1138 trace_xfs_buf_unlock(bp, _RET_IP_);
1139}
1140
1141STATIC void
1142xfs_buf_wait_unpin(
1143 struct xfs_buf *bp)
1144{
1145 DECLARE_WAITQUEUE (wait, current);
1146
1147 if (atomic_read(&bp->b_pin_count) == 0)
1148 return;
1149
1150 add_wait_queue(&bp->b_waiters, &wait);
1151 for (;;) {
1152 set_current_state(TASK_UNINTERRUPTIBLE);
1153 if (atomic_read(&bp->b_pin_count) == 0)
1154 break;
1155 io_schedule();
1156 }
1157 remove_wait_queue(&bp->b_waiters, &wait);
1158 set_current_state(TASK_RUNNING);
1159}
1160
1161static void
1162xfs_buf_ioerror_alert_ratelimited(
1163 struct xfs_buf *bp)
1164{
1165 static unsigned long lasttime;
1166 static struct xfs_buftarg *lasttarg;
1167
1168 if (bp->b_target != lasttarg ||
1169 time_after(jiffies, (lasttime + 5*HZ))) {
1170 lasttime = jiffies;
1171 xfs_buf_ioerror_alert(bp, __this_address);
1172 }
1173 lasttarg = bp->b_target;
1174}
1175
1176/*
1177 * Account for this latest trip around the retry handler, and decide if
1178 * we've failed enough times to constitute a permanent failure.
1179 */
1180static bool
1181xfs_buf_ioerror_permanent(
1182 struct xfs_buf *bp,
1183 struct xfs_error_cfg *cfg)
1184{
1185 struct xfs_mount *mp = bp->b_mount;
1186
1187 if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
1188 ++bp->b_retries > cfg->max_retries)
1189 return true;
1190 if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1191 time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
1192 return true;
1193
1194 /* At unmount we may treat errors differently */
1195 if (xfs_is_unmounting(mp) && mp->m_fail_unmount)
1196 return true;
1197
1198 return false;
1199}
1200
1201/*
1202 * On a sync write or shutdown we just want to stale the buffer and let the
1203 * caller handle the error in bp->b_error appropriately.
1204 *
1205 * If the write was asynchronous then no one will be looking for the error. If
1206 * this is the first failure of this type, clear the error state and write the
1207 * buffer out again. This means we always retry an async write failure at least
1208 * once, but we also need to set the buffer up to behave correctly now for
1209 * repeated failures.
1210 *
1211 * If we get repeated async write failures, then we take action according to the
1212 * error configuration we have been set up to use.
1213 *
1214 * Returns true if this function took care of error handling and the caller must
1215 * not touch the buffer again. Return false if the caller should proceed with
1216 * normal I/O completion handling.
1217 */
1218static bool
1219xfs_buf_ioend_handle_error(
1220 struct xfs_buf *bp)
1221{
1222 struct xfs_mount *mp = bp->b_mount;
1223 struct xfs_error_cfg *cfg;
1224
1225 /*
1226 * If we've already shutdown the journal because of I/O errors, there's
1227 * no point in giving this a retry.
1228 */
1229 if (xlog_is_shutdown(mp->m_log))
1230 goto out_stale;
1231
1232 xfs_buf_ioerror_alert_ratelimited(bp);
1233
1234 /*
1235 * We're not going to bother about retrying this during recovery.
1236 * One strike!
1237 */
1238 if (bp->b_flags & _XBF_LOGRECOVERY) {
1239 xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1240 return false;
1241 }
1242
1243 /*
1244 * Synchronous writes will have callers process the error.
1245 */
1246 if (!(bp->b_flags & XBF_ASYNC))
1247 goto out_stale;
1248
1249 trace_xfs_buf_iodone_async(bp, _RET_IP_);
1250
1251 cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
1252 if (bp->b_last_error != bp->b_error ||
1253 !(bp->b_flags & (XBF_STALE | XBF_WRITE_FAIL))) {
1254 bp->b_last_error = bp->b_error;
1255 if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1256 !bp->b_first_retry_time)
1257 bp->b_first_retry_time = jiffies;
1258 goto resubmit;
1259 }
1260
1261 /*
1262 * Permanent error - we need to trigger a shutdown if we haven't already
1263 * to indicate that inconsistency will result from this action.
1264 */
1265 if (xfs_buf_ioerror_permanent(bp, cfg)) {
1266 xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1267 goto out_stale;
1268 }
1269
1270 /* Still considered a transient error. Caller will schedule retries. */
1271 if (bp->b_flags & _XBF_INODES)
1272 xfs_buf_inode_io_fail(bp);
1273 else if (bp->b_flags & _XBF_DQUOTS)
1274 xfs_buf_dquot_io_fail(bp);
1275 else
1276 ASSERT(list_empty(&bp->b_li_list));
1277 xfs_buf_ioerror(bp, 0);
1278 xfs_buf_relse(bp);
1279 return true;
1280
1281resubmit:
1282 xfs_buf_ioerror(bp, 0);
1283 bp->b_flags |= (XBF_DONE | XBF_WRITE_FAIL);
1284 xfs_buf_submit(bp);
1285 return true;
1286out_stale:
1287 xfs_buf_stale(bp);
1288 bp->b_flags |= XBF_DONE;
1289 bp->b_flags &= ~XBF_WRITE;
1290 trace_xfs_buf_error_relse(bp, _RET_IP_);
1291 return false;
1292}
1293
1294static void
1295xfs_buf_ioend(
1296 struct xfs_buf *bp)
1297{
1298 trace_xfs_buf_iodone(bp, _RET_IP_);
1299
1300 /*
1301 * Pull in IO completion errors now. We are guaranteed to be running
1302 * single threaded, so we don't need the lock to read b_io_error.
1303 */
1304 if (!bp->b_error && bp->b_io_error)
1305 xfs_buf_ioerror(bp, bp->b_io_error);
1306
1307 if (bp->b_flags & XBF_READ) {
1308 if (!bp->b_error && bp->b_ops)
1309 bp->b_ops->verify_read(bp);
1310 if (!bp->b_error)
1311 bp->b_flags |= XBF_DONE;
1312 } else {
1313 if (!bp->b_error) {
1314 bp->b_flags &= ~XBF_WRITE_FAIL;
1315 bp->b_flags |= XBF_DONE;
1316 }
1317
1318 if (unlikely(bp->b_error) && xfs_buf_ioend_handle_error(bp))
1319 return;
1320
1321 /* clear the retry state */
1322 bp->b_last_error = 0;
1323 bp->b_retries = 0;
1324 bp->b_first_retry_time = 0;
1325
1326 /*
1327 * Note that for things like remote attribute buffers, there may
1328 * not be a buffer log item here, so processing the buffer log
1329 * item must remain optional.
1330 */
1331 if (bp->b_log_item)
1332 xfs_buf_item_done(bp);
1333
1334 if (bp->b_flags & _XBF_INODES)
1335 xfs_buf_inode_iodone(bp);
1336 else if (bp->b_flags & _XBF_DQUOTS)
1337 xfs_buf_dquot_iodone(bp);
1338
1339 }
1340
1341 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD |
1342 _XBF_LOGRECOVERY);
1343
1344 if (bp->b_flags & XBF_ASYNC)
1345 xfs_buf_relse(bp);
1346 else
1347 complete(&bp->b_iowait);
1348}
1349
1350static void
1351xfs_buf_ioend_work(
1352 struct work_struct *work)
1353{
1354 struct xfs_buf *bp =
1355 container_of(work, struct xfs_buf, b_ioend_work);
1356
1357 xfs_buf_ioend(bp);
1358}
1359
1360static void
1361xfs_buf_ioend_async(
1362 struct xfs_buf *bp)
1363{
1364 INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
1365 queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
1366}
1367
1368void
1369__xfs_buf_ioerror(
1370 struct xfs_buf *bp,
1371 int error,
1372 xfs_failaddr_t failaddr)
1373{
1374 ASSERT(error <= 0 && error >= -1000);
1375 bp->b_error = error;
1376 trace_xfs_buf_ioerror(bp, error, failaddr);
1377}
1378
1379void
1380xfs_buf_ioerror_alert(
1381 struct xfs_buf *bp,
1382 xfs_failaddr_t func)
1383{
1384 xfs_buf_alert_ratelimited(bp, "XFS: metadata IO error",
1385 "metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
1386 func, (uint64_t)xfs_buf_daddr(bp),
1387 bp->b_length, -bp->b_error);
1388}
1389
1390/*
1391 * To simulate an I/O failure, the buffer must be locked and held with at least
1392 * three references. The LRU reference is dropped by the stale call. The buf
1393 * item reference is dropped via ioend processing. The third reference is owned
1394 * by the caller and is dropped on I/O completion if the buffer is XBF_ASYNC.
1395 */
1396void
1397xfs_buf_ioend_fail(
1398 struct xfs_buf *bp)
1399{
1400 bp->b_flags &= ~XBF_DONE;
1401 xfs_buf_stale(bp);
1402 xfs_buf_ioerror(bp, -EIO);
1403 xfs_buf_ioend(bp);
1404}
1405
1406int
1407xfs_bwrite(
1408 struct xfs_buf *bp)
1409{
1410 int error;
1411
1412 ASSERT(xfs_buf_islocked(bp));
1413
1414 bp->b_flags |= XBF_WRITE;
1415 bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
1416 XBF_DONE);
1417
1418 error = xfs_buf_submit(bp);
1419 if (error)
1420 xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
1421 return error;
1422}
1423
1424static void
1425xfs_buf_bio_end_io(
1426 struct bio *bio)
1427{
1428 struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private;
1429
1430 if (!bio->bi_status &&
1431 (bp->b_flags & XBF_WRITE) && (bp->b_flags & XBF_ASYNC) &&
1432 XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_IOERROR))
1433 bio->bi_status = BLK_STS_IOERR;
1434
1435 /*
1436 * don't overwrite existing errors - otherwise we can lose errors on
1437 * buffers that require multiple bios to complete.
1438 */
1439 if (bio->bi_status) {
1440 int error = blk_status_to_errno(bio->bi_status);
1441
1442 cmpxchg(&bp->b_io_error, 0, error);
1443 }
1444
1445 if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1446 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1447
1448 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1449 xfs_buf_ioend_async(bp);
1450 bio_put(bio);
1451}
1452
1453static void
1454xfs_buf_ioapply_map(
1455 struct xfs_buf *bp,
1456 int map,
1457 int *buf_offset,
1458 int *count,
1459 blk_opf_t op)
1460{
1461 int page_index;
1462 unsigned int total_nr_pages = bp->b_page_count;
1463 int nr_pages;
1464 struct bio *bio;
1465 sector_t sector = bp->b_maps[map].bm_bn;
1466 int size;
1467 int offset;
1468
1469 /* skip the pages in the buffer before the start offset */
1470 page_index = 0;
1471 offset = *buf_offset;
1472 while (offset >= PAGE_SIZE) {
1473 page_index++;
1474 offset -= PAGE_SIZE;
1475 }
1476
1477 /*
1478 * Limit the IO size to the length of the current vector, and update the
1479 * remaining IO count for the next time around.
1480 */
1481 size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1482 *count -= size;
1483 *buf_offset += size;
1484
1485next_chunk:
1486 atomic_inc(&bp->b_io_remaining);
1487 nr_pages = bio_max_segs(total_nr_pages);
1488
1489 bio = bio_alloc(bp->b_target->bt_bdev, nr_pages, op, GFP_NOIO);
1490 bio->bi_iter.bi_sector = sector;
1491 bio->bi_end_io = xfs_buf_bio_end_io;
1492 bio->bi_private = bp;
1493
1494 for (; size && nr_pages; nr_pages--, page_index++) {
1495 int rbytes, nbytes = PAGE_SIZE - offset;
1496
1497 if (nbytes > size)
1498 nbytes = size;
1499
1500 rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
1501 offset);
1502 if (rbytes < nbytes)
1503 break;
1504
1505 offset = 0;
1506 sector += BTOBB(nbytes);
1507 size -= nbytes;
1508 total_nr_pages--;
1509 }
1510
1511 if (likely(bio->bi_iter.bi_size)) {
1512 if (xfs_buf_is_vmapped(bp)) {
1513 flush_kernel_vmap_range(bp->b_addr,
1514 xfs_buf_vmap_len(bp));
1515 }
1516 submit_bio(bio);
1517 if (size)
1518 goto next_chunk;
1519 } else {
1520 /*
1521 * This is guaranteed not to be the last io reference count
1522 * because the caller (xfs_buf_submit) holds a count itself.
1523 */
1524 atomic_dec(&bp->b_io_remaining);
1525 xfs_buf_ioerror(bp, -EIO);
1526 bio_put(bio);
1527 }
1528
1529}
1530
1531STATIC void
1532_xfs_buf_ioapply(
1533 struct xfs_buf *bp)
1534{
1535 struct blk_plug plug;
1536 blk_opf_t op;
1537 int offset;
1538 int size;
1539 int i;
1540
1541 /*
1542 * Make sure we capture only current IO errors rather than stale errors
1543 * left over from previous use of the buffer (e.g. failed readahead).
1544 */
1545 bp->b_error = 0;
1546
1547 if (bp->b_flags & XBF_WRITE) {
1548 op = REQ_OP_WRITE;
1549
1550 /*
1551 * Run the write verifier callback function if it exists. If
1552 * this function fails it will mark the buffer with an error and
1553 * the IO should not be dispatched.
1554 */
1555 if (bp->b_ops) {
1556 bp->b_ops->verify_write(bp);
1557 if (bp->b_error) {
1558 xfs_force_shutdown(bp->b_mount,
1559 SHUTDOWN_CORRUPT_INCORE);
1560 return;
1561 }
1562 } else if (bp->b_rhash_key != XFS_BUF_DADDR_NULL) {
1563 struct xfs_mount *mp = bp->b_mount;
1564
1565 /*
1566 * non-crc filesystems don't attach verifiers during
1567 * log recovery, so don't warn for such filesystems.
1568 */
1569 if (xfs_has_crc(mp)) {
1570 xfs_warn(mp,
1571 "%s: no buf ops on daddr 0x%llx len %d",
1572 __func__, xfs_buf_daddr(bp),
1573 bp->b_length);
1574 xfs_hex_dump(bp->b_addr,
1575 XFS_CORRUPTION_DUMP_LEN);
1576 dump_stack();
1577 }
1578 }
1579 } else {
1580 op = REQ_OP_READ;
1581 if (bp->b_flags & XBF_READ_AHEAD)
1582 op |= REQ_RAHEAD;
1583 }
1584
1585 /* we only use the buffer cache for meta-data */
1586 op |= REQ_META;
1587
1588 /*
1589 * Walk all the vectors issuing IO on them. Set up the initial offset
1590 * into the buffer and the desired IO size before we start -
1591 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1592 * subsequent call.
1593 */
1594 offset = bp->b_offset;
1595 size = BBTOB(bp->b_length);
1596 blk_start_plug(&plug);
1597 for (i = 0; i < bp->b_map_count; i++) {
1598 xfs_buf_ioapply_map(bp, i, &offset, &size, op);
1599 if (bp->b_error)
1600 break;
1601 if (size <= 0)
1602 break; /* all done */
1603 }
1604 blk_finish_plug(&plug);
1605}
1606
1607/*
1608 * Wait for I/O completion of a sync buffer and return the I/O error code.
1609 */
1610static int
1611xfs_buf_iowait(
1612 struct xfs_buf *bp)
1613{
1614 ASSERT(!(bp->b_flags & XBF_ASYNC));
1615
1616 trace_xfs_buf_iowait(bp, _RET_IP_);
1617 wait_for_completion(&bp->b_iowait);
1618 trace_xfs_buf_iowait_done(bp, _RET_IP_);
1619
1620 return bp->b_error;
1621}
1622
1623/*
1624 * Buffer I/O submission path, read or write. Asynchronous submission transfers
1625 * the buffer lock ownership and the current reference to the IO. It is not
1626 * safe to reference the buffer after a call to this function unless the caller
1627 * holds an additional reference itself.
1628 */
1629static int
1630__xfs_buf_submit(
1631 struct xfs_buf *bp,
1632 bool wait)
1633{
1634 int error = 0;
1635
1636 trace_xfs_buf_submit(bp, _RET_IP_);
1637
1638 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1639
1640 /*
1641 * On log shutdown we stale and complete the buffer immediately. We can
1642 * be called to read the superblock before the log has been set up, so
1643 * be careful checking the log state.
1644 *
1645 * Checking the mount shutdown state here can result in the log tail
1646 * moving inappropriately on disk as the log may not yet be shut down.
1647 * i.e. failing this buffer on mount shutdown can remove it from the AIL
1648 * and move the tail of the log forwards without having written this
1649 * buffer to disk. This corrupts the log tail state in memory, and
1650 * because the log may not be shut down yet, it can then be propagated
1651 * to disk before the log is shutdown. Hence we check log shutdown
1652 * state here rather than mount state to avoid corrupting the log tail
1653 * on shutdown.
1654 */
1655 if (bp->b_mount->m_log &&
1656 xlog_is_shutdown(bp->b_mount->m_log)) {
1657 xfs_buf_ioend_fail(bp);
1658 return -EIO;
1659 }
1660
1661 /*
1662 * Grab a reference so the buffer does not go away underneath us. For
1663 * async buffers, I/O completion drops the callers reference, which
1664 * could occur before submission returns.
1665 */
1666 xfs_buf_hold(bp);
1667
1668 if (bp->b_flags & XBF_WRITE)
1669 xfs_buf_wait_unpin(bp);
1670
1671 /* clear the internal error state to avoid spurious errors */
1672 bp->b_io_error = 0;
1673
1674 /*
1675 * Set the count to 1 initially, this will stop an I/O completion
1676 * callout which happens before we have started all the I/O from calling
1677 * xfs_buf_ioend too early.
1678 */
1679 atomic_set(&bp->b_io_remaining, 1);
1680 if (bp->b_flags & XBF_ASYNC)
1681 xfs_buf_ioacct_inc(bp);
1682 _xfs_buf_ioapply(bp);
1683
1684 /*
1685 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1686 * reference we took above. If we drop it to zero, run completion so
1687 * that we don't return to the caller with completion still pending.
1688 */
1689 if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1690 if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
1691 xfs_buf_ioend(bp);
1692 else
1693 xfs_buf_ioend_async(bp);
1694 }
1695
1696 if (wait)
1697 error = xfs_buf_iowait(bp);
1698
1699 /*
1700 * Release the hold that keeps the buffer referenced for the entire
1701 * I/O. Note that if the buffer is async, it is not safe to reference
1702 * after this release.
1703 */
1704 xfs_buf_rele(bp);
1705 return error;
1706}
1707
1708void *
1709xfs_buf_offset(
1710 struct xfs_buf *bp,
1711 size_t offset)
1712{
1713 struct page *page;
1714
1715 if (bp->b_addr)
1716 return bp->b_addr + offset;
1717
1718 page = bp->b_pages[offset >> PAGE_SHIFT];
1719 return page_address(page) + (offset & (PAGE_SIZE-1));
1720}
1721
1722void
1723xfs_buf_zero(
1724 struct xfs_buf *bp,
1725 size_t boff,
1726 size_t bsize)
1727{
1728 size_t bend;
1729
1730 bend = boff + bsize;
1731 while (boff < bend) {
1732 struct page *page;
1733 int page_index, page_offset, csize;
1734
1735 page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1736 page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1737 page = bp->b_pages[page_index];
1738 csize = min_t(size_t, PAGE_SIZE - page_offset,
1739 BBTOB(bp->b_length) - boff);
1740
1741 ASSERT((csize + page_offset) <= PAGE_SIZE);
1742
1743 memset(page_address(page) + page_offset, 0, csize);
1744
1745 boff += csize;
1746 }
1747}
1748
1749/*
1750 * Log a message about and stale a buffer that a caller has decided is corrupt.
1751 *
1752 * This function should be called for the kinds of metadata corruption that
1753 * cannot be detect from a verifier, such as incorrect inter-block relationship
1754 * data. Do /not/ call this function from a verifier function.
1755 *
1756 * The buffer must be XBF_DONE prior to the call. Afterwards, the buffer will
1757 * be marked stale, but b_error will not be set. The caller is responsible for
1758 * releasing the buffer or fixing it.
1759 */
1760void
1761__xfs_buf_mark_corrupt(
1762 struct xfs_buf *bp,
1763 xfs_failaddr_t fa)
1764{
1765 ASSERT(bp->b_flags & XBF_DONE);
1766
1767 xfs_buf_corruption_error(bp, fa);
1768 xfs_buf_stale(bp);
1769}
1770
1771/*
1772 * Handling of buffer targets (buftargs).
1773 */
1774
1775/*
1776 * Wait for any bufs with callbacks that have been submitted but have not yet
1777 * returned. These buffers will have an elevated hold count, so wait on those
1778 * while freeing all the buffers only held by the LRU.
1779 */
1780static enum lru_status
1781xfs_buftarg_drain_rele(
1782 struct list_head *item,
1783 struct list_lru_one *lru,
1784 spinlock_t *lru_lock,
1785 void *arg)
1786
1787{
1788 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1789 struct list_head *dispose = arg;
1790
1791 if (atomic_read(&bp->b_hold) > 1) {
1792 /* need to wait, so skip it this pass */
1793 trace_xfs_buf_drain_buftarg(bp, _RET_IP_);
1794 return LRU_SKIP;
1795 }
1796 if (!spin_trylock(&bp->b_lock))
1797 return LRU_SKIP;
1798
1799 /*
1800 * clear the LRU reference count so the buffer doesn't get
1801 * ignored in xfs_buf_rele().
1802 */
1803 atomic_set(&bp->b_lru_ref, 0);
1804 bp->b_state |= XFS_BSTATE_DISPOSE;
1805 list_lru_isolate_move(lru, item, dispose);
1806 spin_unlock(&bp->b_lock);
1807 return LRU_REMOVED;
1808}
1809
1810/*
1811 * Wait for outstanding I/O on the buftarg to complete.
1812 */
1813void
1814xfs_buftarg_wait(
1815 struct xfs_buftarg *btp)
1816{
1817 /*
1818 * First wait on the buftarg I/O count for all in-flight buffers to be
1819 * released. This is critical as new buffers do not make the LRU until
1820 * they are released.
1821 *
1822 * Next, flush the buffer workqueue to ensure all completion processing
1823 * has finished. Just waiting on buffer locks is not sufficient for
1824 * async IO as the reference count held over IO is not released until
1825 * after the buffer lock is dropped. Hence we need to ensure here that
1826 * all reference counts have been dropped before we start walking the
1827 * LRU list.
1828 */
1829 while (percpu_counter_sum(&btp->bt_io_count))
1830 delay(100);
1831 flush_workqueue(btp->bt_mount->m_buf_workqueue);
1832}
1833
1834void
1835xfs_buftarg_drain(
1836 struct xfs_buftarg *btp)
1837{
1838 LIST_HEAD(dispose);
1839 int loop = 0;
1840 bool write_fail = false;
1841
1842 xfs_buftarg_wait(btp);
1843
1844 /* loop until there is nothing left on the lru list. */
1845 while (list_lru_count(&btp->bt_lru)) {
1846 list_lru_walk(&btp->bt_lru, xfs_buftarg_drain_rele,
1847 &dispose, LONG_MAX);
1848
1849 while (!list_empty(&dispose)) {
1850 struct xfs_buf *bp;
1851 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1852 list_del_init(&bp->b_lru);
1853 if (bp->b_flags & XBF_WRITE_FAIL) {
1854 write_fail = true;
1855 xfs_buf_alert_ratelimited(bp,
1856 "XFS: Corruption Alert",
1857"Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
1858 (long long)xfs_buf_daddr(bp));
1859 }
1860 xfs_buf_rele(bp);
1861 }
1862 if (loop++ != 0)
1863 delay(100);
1864 }
1865
1866 /*
1867 * If one or more failed buffers were freed, that means dirty metadata
1868 * was thrown away. This should only ever happen after I/O completion
1869 * handling has elevated I/O error(s) to permanent failures and shuts
1870 * down the journal.
1871 */
1872 if (write_fail) {
1873 ASSERT(xlog_is_shutdown(btp->bt_mount->m_log));
1874 xfs_alert(btp->bt_mount,
1875 "Please run xfs_repair to determine the extent of the problem.");
1876 }
1877}
1878
1879static enum lru_status
1880xfs_buftarg_isolate(
1881 struct list_head *item,
1882 struct list_lru_one *lru,
1883 spinlock_t *lru_lock,
1884 void *arg)
1885{
1886 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1887 struct list_head *dispose = arg;
1888
1889 /*
1890 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1891 * If we fail to get the lock, just skip it.
1892 */
1893 if (!spin_trylock(&bp->b_lock))
1894 return LRU_SKIP;
1895 /*
1896 * Decrement the b_lru_ref count unless the value is already
1897 * zero. If the value is already zero, we need to reclaim the
1898 * buffer, otherwise it gets another trip through the LRU.
1899 */
1900 if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1901 spin_unlock(&bp->b_lock);
1902 return LRU_ROTATE;
1903 }
1904
1905 bp->b_state |= XFS_BSTATE_DISPOSE;
1906 list_lru_isolate_move(lru, item, dispose);
1907 spin_unlock(&bp->b_lock);
1908 return LRU_REMOVED;
1909}
1910
1911static unsigned long
1912xfs_buftarg_shrink_scan(
1913 struct shrinker *shrink,
1914 struct shrink_control *sc)
1915{
1916 struct xfs_buftarg *btp = shrink->private_data;
1917 LIST_HEAD(dispose);
1918 unsigned long freed;
1919
1920 freed = list_lru_shrink_walk(&btp->bt_lru, sc,
1921 xfs_buftarg_isolate, &dispose);
1922
1923 while (!list_empty(&dispose)) {
1924 struct xfs_buf *bp;
1925 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1926 list_del_init(&bp->b_lru);
1927 xfs_buf_rele(bp);
1928 }
1929
1930 return freed;
1931}
1932
1933static unsigned long
1934xfs_buftarg_shrink_count(
1935 struct shrinker *shrink,
1936 struct shrink_control *sc)
1937{
1938 struct xfs_buftarg *btp = shrink->private_data;
1939 return list_lru_shrink_count(&btp->bt_lru, sc);
1940}
1941
1942void
1943xfs_free_buftarg(
1944 struct xfs_buftarg *btp)
1945{
1946 shrinker_free(btp->bt_shrinker);
1947 ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
1948 percpu_counter_destroy(&btp->bt_io_count);
1949 list_lru_destroy(&btp->bt_lru);
1950
1951 fs_put_dax(btp->bt_daxdev, btp->bt_mount);
1952 /* the main block device is closed by kill_block_super */
1953 if (btp->bt_bdev != btp->bt_mount->m_super->s_bdev)
1954 bdev_release(btp->bt_bdev_handle);
1955
1956 kmem_free(btp);
1957}
1958
1959int
1960xfs_setsize_buftarg(
1961 xfs_buftarg_t *btp,
1962 unsigned int sectorsize)
1963{
1964 /* Set up metadata sector size info */
1965 btp->bt_meta_sectorsize = sectorsize;
1966 btp->bt_meta_sectormask = sectorsize - 1;
1967
1968 if (set_blocksize(btp->bt_bdev, sectorsize)) {
1969 xfs_warn(btp->bt_mount,
1970 "Cannot set_blocksize to %u on device %pg",
1971 sectorsize, btp->bt_bdev);
1972 return -EINVAL;
1973 }
1974
1975 /* Set up device logical sector size mask */
1976 btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);
1977 btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;
1978
1979 return 0;
1980}
1981
1982/*
1983 * When allocating the initial buffer target we have not yet
1984 * read in the superblock, so don't know what sized sectors
1985 * are being used at this early stage. Play safe.
1986 */
1987STATIC int
1988xfs_setsize_buftarg_early(
1989 xfs_buftarg_t *btp)
1990{
1991 return xfs_setsize_buftarg(btp, bdev_logical_block_size(btp->bt_bdev));
1992}
1993
1994struct xfs_buftarg *
1995xfs_alloc_buftarg(
1996 struct xfs_mount *mp,
1997 struct bdev_handle *bdev_handle)
1998{
1999 xfs_buftarg_t *btp;
2000 const struct dax_holder_operations *ops = NULL;
2001
2002#if defined(CONFIG_FS_DAX) && defined(CONFIG_MEMORY_FAILURE)
2003 ops = &xfs_dax_holder_operations;
2004#endif
2005 btp = kmem_zalloc(sizeof(*btp), KM_NOFS);
2006
2007 btp->bt_mount = mp;
2008 btp->bt_bdev_handle = bdev_handle;
2009 btp->bt_dev = bdev_handle->bdev->bd_dev;
2010 btp->bt_bdev = bdev_handle->bdev;
2011 btp->bt_daxdev = fs_dax_get_by_bdev(btp->bt_bdev, &btp->bt_dax_part_off,
2012 mp, ops);
2013
2014 /*
2015 * Buffer IO error rate limiting. Limit it to no more than 10 messages
2016 * per 30 seconds so as to not spam logs too much on repeated errors.
2017 */
2018 ratelimit_state_init(&btp->bt_ioerror_rl, 30 * HZ,
2019 DEFAULT_RATELIMIT_BURST);
2020
2021 if (xfs_setsize_buftarg_early(btp))
2022 goto error_free;
2023
2024 if (list_lru_init(&btp->bt_lru))
2025 goto error_free;
2026
2027 if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
2028 goto error_lru;
2029
2030 btp->bt_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE, "xfs-buf:%s",
2031 mp->m_super->s_id);
2032 if (!btp->bt_shrinker)
2033 goto error_pcpu;
2034
2035 btp->bt_shrinker->count_objects = xfs_buftarg_shrink_count;
2036 btp->bt_shrinker->scan_objects = xfs_buftarg_shrink_scan;
2037 btp->bt_shrinker->private_data = btp;
2038
2039 shrinker_register(btp->bt_shrinker);
2040
2041 return btp;
2042
2043error_pcpu:
2044 percpu_counter_destroy(&btp->bt_io_count);
2045error_lru:
2046 list_lru_destroy(&btp->bt_lru);
2047error_free:
2048 kmem_free(btp);
2049 return NULL;
2050}
2051
2052static inline void
2053xfs_buf_list_del(
2054 struct xfs_buf *bp)
2055{
2056 list_del_init(&bp->b_list);
2057 wake_up_var(&bp->b_list);
2058}
2059
2060/*
2061 * Cancel a delayed write list.
2062 *
2063 * Remove each buffer from the list, clear the delwri queue flag and drop the
2064 * associated buffer reference.
2065 */
2066void
2067xfs_buf_delwri_cancel(
2068 struct list_head *list)
2069{
2070 struct xfs_buf *bp;
2071
2072 while (!list_empty(list)) {
2073 bp = list_first_entry(list, struct xfs_buf, b_list);
2074
2075 xfs_buf_lock(bp);
2076 bp->b_flags &= ~_XBF_DELWRI_Q;
2077 xfs_buf_list_del(bp);
2078 xfs_buf_relse(bp);
2079 }
2080}
2081
2082/*
2083 * Add a buffer to the delayed write list.
2084 *
2085 * This queues a buffer for writeout if it hasn't already been. Note that
2086 * neither this routine nor the buffer list submission functions perform
2087 * any internal synchronization. It is expected that the lists are thread-local
2088 * to the callers.
2089 *
2090 * Returns true if we queued up the buffer, or false if it already had
2091 * been on the buffer list.
2092 */
2093bool
2094xfs_buf_delwri_queue(
2095 struct xfs_buf *bp,
2096 struct list_head *list)
2097{
2098 ASSERT(xfs_buf_islocked(bp));
2099 ASSERT(!(bp->b_flags & XBF_READ));
2100
2101 /*
2102 * If the buffer is already marked delwri it already is queued up
2103 * by someone else for imediate writeout. Just ignore it in that
2104 * case.
2105 */
2106 if (bp->b_flags & _XBF_DELWRI_Q) {
2107 trace_xfs_buf_delwri_queued(bp, _RET_IP_);
2108 return false;
2109 }
2110
2111 trace_xfs_buf_delwri_queue(bp, _RET_IP_);
2112
2113 /*
2114 * If a buffer gets written out synchronously or marked stale while it
2115 * is on a delwri list we lazily remove it. To do this, the other party
2116 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
2117 * It remains referenced and on the list. In a rare corner case it
2118 * might get readded to a delwri list after the synchronous writeout, in
2119 * which case we need just need to re-add the flag here.
2120 */
2121 bp->b_flags |= _XBF_DELWRI_Q;
2122 if (list_empty(&bp->b_list)) {
2123 atomic_inc(&bp->b_hold);
2124 list_add_tail(&bp->b_list, list);
2125 }
2126
2127 return true;
2128}
2129
2130/*
2131 * Queue a buffer to this delwri list as part of a data integrity operation.
2132 * If the buffer is on any other delwri list, we'll wait for that to clear
2133 * so that the caller can submit the buffer for IO and wait for the result.
2134 * Callers must ensure the buffer is not already on the list.
2135 */
2136void
2137xfs_buf_delwri_queue_here(
2138 struct xfs_buf *bp,
2139 struct list_head *buffer_list)
2140{
2141 /*
2142 * We need this buffer to end up on the /caller's/ delwri list, not any
2143 * old list. This can happen if the buffer is marked stale (which
2144 * clears DELWRI_Q) after the AIL queues the buffer to its list but
2145 * before the AIL has a chance to submit the list.
2146 */
2147 while (!list_empty(&bp->b_list)) {
2148 xfs_buf_unlock(bp);
2149 wait_var_event(&bp->b_list, list_empty(&bp->b_list));
2150 xfs_buf_lock(bp);
2151 }
2152
2153 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
2154
2155 xfs_buf_delwri_queue(bp, buffer_list);
2156}
2157
2158/*
2159 * Compare function is more complex than it needs to be because
2160 * the return value is only 32 bits and we are doing comparisons
2161 * on 64 bit values
2162 */
2163static int
2164xfs_buf_cmp(
2165 void *priv,
2166 const struct list_head *a,
2167 const struct list_head *b)
2168{
2169 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
2170 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
2171 xfs_daddr_t diff;
2172
2173 diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
2174 if (diff < 0)
2175 return -1;
2176 if (diff > 0)
2177 return 1;
2178 return 0;
2179}
2180
2181/*
2182 * Submit buffers for write. If wait_list is specified, the buffers are
2183 * submitted using sync I/O and placed on the wait list such that the caller can
2184 * iowait each buffer. Otherwise async I/O is used and the buffers are released
2185 * at I/O completion time. In either case, buffers remain locked until I/O
2186 * completes and the buffer is released from the queue.
2187 */
2188static int
2189xfs_buf_delwri_submit_buffers(
2190 struct list_head *buffer_list,
2191 struct list_head *wait_list)
2192{
2193 struct xfs_buf *bp, *n;
2194 int pinned = 0;
2195 struct blk_plug plug;
2196
2197 list_sort(NULL, buffer_list, xfs_buf_cmp);
2198
2199 blk_start_plug(&plug);
2200 list_for_each_entry_safe(bp, n, buffer_list, b_list) {
2201 if (!wait_list) {
2202 if (!xfs_buf_trylock(bp))
2203 continue;
2204 if (xfs_buf_ispinned(bp)) {
2205 xfs_buf_unlock(bp);
2206 pinned++;
2207 continue;
2208 }
2209 } else {
2210 xfs_buf_lock(bp);
2211 }
2212
2213 /*
2214 * Someone else might have written the buffer synchronously or
2215 * marked it stale in the meantime. In that case only the
2216 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
2217 * reference and remove it from the list here.
2218 */
2219 if (!(bp->b_flags & _XBF_DELWRI_Q)) {
2220 xfs_buf_list_del(bp);
2221 xfs_buf_relse(bp);
2222 continue;
2223 }
2224
2225 trace_xfs_buf_delwri_split(bp, _RET_IP_);
2226
2227 /*
2228 * If we have a wait list, each buffer (and associated delwri
2229 * queue reference) transfers to it and is submitted
2230 * synchronously. Otherwise, drop the buffer from the delwri
2231 * queue and submit async.
2232 */
2233 bp->b_flags &= ~_XBF_DELWRI_Q;
2234 bp->b_flags |= XBF_WRITE;
2235 if (wait_list) {
2236 bp->b_flags &= ~XBF_ASYNC;
2237 list_move_tail(&bp->b_list, wait_list);
2238 } else {
2239 bp->b_flags |= XBF_ASYNC;
2240 xfs_buf_list_del(bp);
2241 }
2242 __xfs_buf_submit(bp, false);
2243 }
2244 blk_finish_plug(&plug);
2245
2246 return pinned;
2247}
2248
2249/*
2250 * Write out a buffer list asynchronously.
2251 *
2252 * This will take the @buffer_list, write all non-locked and non-pinned buffers
2253 * out and not wait for I/O completion on any of the buffers. This interface
2254 * is only safely useable for callers that can track I/O completion by higher
2255 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
2256 * function.
2257 *
2258 * Note: this function will skip buffers it would block on, and in doing so
2259 * leaves them on @buffer_list so they can be retried on a later pass. As such,
2260 * it is up to the caller to ensure that the buffer list is fully submitted or
2261 * cancelled appropriately when they are finished with the list. Failure to
2262 * cancel or resubmit the list until it is empty will result in leaked buffers
2263 * at unmount time.
2264 */
2265int
2266xfs_buf_delwri_submit_nowait(
2267 struct list_head *buffer_list)
2268{
2269 return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
2270}
2271
2272/*
2273 * Write out a buffer list synchronously.
2274 *
2275 * This will take the @buffer_list, write all buffers out and wait for I/O
2276 * completion on all of the buffers. @buffer_list is consumed by the function,
2277 * so callers must have some other way of tracking buffers if they require such
2278 * functionality.
2279 */
2280int
2281xfs_buf_delwri_submit(
2282 struct list_head *buffer_list)
2283{
2284 LIST_HEAD (wait_list);
2285 int error = 0, error2;
2286 struct xfs_buf *bp;
2287
2288 xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);
2289
2290 /* Wait for IO to complete. */
2291 while (!list_empty(&wait_list)) {
2292 bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
2293
2294 xfs_buf_list_del(bp);
2295
2296 /*
2297 * Wait on the locked buffer, check for errors and unlock and
2298 * release the delwri queue reference.
2299 */
2300 error2 = xfs_buf_iowait(bp);
2301 xfs_buf_relse(bp);
2302 if (!error)
2303 error = error2;
2304 }
2305
2306 return error;
2307}
2308
2309/*
2310 * Push a single buffer on a delwri queue.
2311 *
2312 * The purpose of this function is to submit a single buffer of a delwri queue
2313 * and return with the buffer still on the original queue. The waiting delwri
2314 * buffer submission infrastructure guarantees transfer of the delwri queue
2315 * buffer reference to a temporary wait list. We reuse this infrastructure to
2316 * transfer the buffer back to the original queue.
2317 *
2318 * Note the buffer transitions from the queued state, to the submitted and wait
2319 * listed state and back to the queued state during this call. The buffer
2320 * locking and queue management logic between _delwri_pushbuf() and
2321 * _delwri_queue() guarantee that the buffer cannot be queued to another list
2322 * before returning.
2323 */
2324int
2325xfs_buf_delwri_pushbuf(
2326 struct xfs_buf *bp,
2327 struct list_head *buffer_list)
2328{
2329 LIST_HEAD (submit_list);
2330 int error;
2331
2332 ASSERT(bp->b_flags & _XBF_DELWRI_Q);
2333
2334 trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);
2335
2336 /*
2337 * Isolate the buffer to a new local list so we can submit it for I/O
2338 * independently from the rest of the original list.
2339 */
2340 xfs_buf_lock(bp);
2341 list_move(&bp->b_list, &submit_list);
2342 xfs_buf_unlock(bp);
2343
2344 /*
2345 * Delwri submission clears the DELWRI_Q buffer flag and returns with
2346 * the buffer on the wait list with the original reference. Rather than
2347 * bounce the buffer from a local wait list back to the original list
2348 * after I/O completion, reuse the original list as the wait list.
2349 */
2350 xfs_buf_delwri_submit_buffers(&submit_list, buffer_list);
2351
2352 /*
2353 * The buffer is now locked, under I/O and wait listed on the original
2354 * delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
2355 * return with the buffer unlocked and on the original queue.
2356 */
2357 error = xfs_buf_iowait(bp);
2358 bp->b_flags |= _XBF_DELWRI_Q;
2359 xfs_buf_unlock(bp);
2360
2361 return error;
2362}
2363
2364void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
2365{
2366 /*
2367 * Set the lru reference count to 0 based on the error injection tag.
2368 * This allows userspace to disrupt buffer caching for debug/testing
2369 * purposes.
2370 */
2371 if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
2372 lru_ref = 0;
2373
2374 atomic_set(&bp->b_lru_ref, lru_ref);
2375}
2376
2377/*
2378 * Verify an on-disk magic value against the magic value specified in the
2379 * verifier structure. The verifier magic is in disk byte order so the caller is
2380 * expected to pass the value directly from disk.
2381 */
2382bool
2383xfs_verify_magic(
2384 struct xfs_buf *bp,
2385 __be32 dmagic)
2386{
2387 struct xfs_mount *mp = bp->b_mount;
2388 int idx;
2389
2390 idx = xfs_has_crc(mp);
2391 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))
2392 return false;
2393 return dmagic == bp->b_ops->magic[idx];
2394}
2395/*
2396 * Verify an on-disk magic value against the magic value specified in the
2397 * verifier structure. The verifier magic is in disk byte order so the caller is
2398 * expected to pass the value directly from disk.
2399 */
2400bool
2401xfs_verify_magic16(
2402 struct xfs_buf *bp,
2403 __be16 dmagic)
2404{
2405 struct xfs_mount *mp = bp->b_mount;
2406 int idx;
2407
2408 idx = xfs_has_crc(mp);
2409 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))
2410 return false;
2411 return dmagic == bp->b_ops->magic16[idx];
2412}