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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_format.h"
38#include "xfs_log_format.h"
39#include "xfs_trans_resv.h"
40#include "xfs_sb.h"
41#include "xfs_mount.h"
42#include "xfs_trace.h"
43#include "xfs_log.h"
44
45static kmem_zone_t *xfs_buf_zone;
46
47#ifdef XFS_BUF_LOCK_TRACKING
48# define XB_SET_OWNER(bp) ((bp)->b_last_holder = current->pid)
49# define XB_CLEAR_OWNER(bp) ((bp)->b_last_holder = -1)
50# define XB_GET_OWNER(bp) ((bp)->b_last_holder)
51#else
52# define XB_SET_OWNER(bp) do { } while (0)
53# define XB_CLEAR_OWNER(bp) do { } while (0)
54# define XB_GET_OWNER(bp) do { } while (0)
55#endif
56
57#define xb_to_gfp(flags) \
58 ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : GFP_NOFS) | __GFP_NOWARN)
59
60
61static inline int
62xfs_buf_is_vmapped(
63 struct xfs_buf *bp)
64{
65 /*
66 * Return true if the buffer is vmapped.
67 *
68 * b_addr is null if the buffer is not mapped, but the code is clever
69 * enough to know it doesn't have to map a single page, so the check has
70 * to be both for b_addr and bp->b_page_count > 1.
71 */
72 return bp->b_addr && bp->b_page_count > 1;
73}
74
75static inline int
76xfs_buf_vmap_len(
77 struct xfs_buf *bp)
78{
79 return (bp->b_page_count * PAGE_SIZE) - bp->b_offset;
80}
81
82/*
83 * Bump the I/O in flight count on the buftarg if we haven't yet done so for
84 * this buffer. The count is incremented once per buffer (per hold cycle)
85 * because the corresponding decrement is deferred to buffer release. Buffers
86 * can undergo I/O multiple times in a hold-release cycle and per buffer I/O
87 * tracking adds unnecessary overhead. This is used for sychronization purposes
88 * with unmount (see xfs_wait_buftarg()), so all we really need is a count of
89 * in-flight buffers.
90 *
91 * Buffers that are never released (e.g., superblock, iclog buffers) must set
92 * the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count
93 * never reaches zero and unmount hangs indefinitely.
94 */
95static inline void
96xfs_buf_ioacct_inc(
97 struct xfs_buf *bp)
98{
99 if (bp->b_flags & (XBF_NO_IOACCT|_XBF_IN_FLIGHT))
100 return;
101
102 ASSERT(bp->b_flags & XBF_ASYNC);
103 bp->b_flags |= _XBF_IN_FLIGHT;
104 percpu_counter_inc(&bp->b_target->bt_io_count);
105}
106
107/*
108 * Clear the in-flight state on a buffer about to be released to the LRU or
109 * freed and unaccount from the buftarg.
110 */
111static inline void
112xfs_buf_ioacct_dec(
113 struct xfs_buf *bp)
114{
115 if (!(bp->b_flags & _XBF_IN_FLIGHT))
116 return;
117
118 bp->b_flags &= ~_XBF_IN_FLIGHT;
119 percpu_counter_dec(&bp->b_target->bt_io_count);
120}
121
122/*
123 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
124 * b_lru_ref count so that the buffer is freed immediately when the buffer
125 * reference count falls to zero. If the buffer is already on the LRU, we need
126 * to remove the reference that LRU holds on the buffer.
127 *
128 * This prevents build-up of stale buffers on the LRU.
129 */
130void
131xfs_buf_stale(
132 struct xfs_buf *bp)
133{
134 ASSERT(xfs_buf_islocked(bp));
135
136 bp->b_flags |= XBF_STALE;
137
138 /*
139 * Clear the delwri status so that a delwri queue walker will not
140 * flush this buffer to disk now that it is stale. The delwri queue has
141 * a reference to the buffer, so this is safe to do.
142 */
143 bp->b_flags &= ~_XBF_DELWRI_Q;
144
145 /*
146 * Once the buffer is marked stale and unlocked, a subsequent lookup
147 * could reset b_flags. There is no guarantee that the buffer is
148 * unaccounted (released to LRU) before that occurs. Drop in-flight
149 * status now to preserve accounting consistency.
150 */
151 xfs_buf_ioacct_dec(bp);
152
153 spin_lock(&bp->b_lock);
154 atomic_set(&bp->b_lru_ref, 0);
155 if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
156 (list_lru_del(&bp->b_target->bt_lru, &bp->b_lru)))
157 atomic_dec(&bp->b_hold);
158
159 ASSERT(atomic_read(&bp->b_hold) >= 1);
160 spin_unlock(&bp->b_lock);
161}
162
163static int
164xfs_buf_get_maps(
165 struct xfs_buf *bp,
166 int map_count)
167{
168 ASSERT(bp->b_maps == NULL);
169 bp->b_map_count = map_count;
170
171 if (map_count == 1) {
172 bp->b_maps = &bp->__b_map;
173 return 0;
174 }
175
176 bp->b_maps = kmem_zalloc(map_count * sizeof(struct xfs_buf_map),
177 KM_NOFS);
178 if (!bp->b_maps)
179 return -ENOMEM;
180 return 0;
181}
182
183/*
184 * Frees b_pages if it was allocated.
185 */
186static void
187xfs_buf_free_maps(
188 struct xfs_buf *bp)
189{
190 if (bp->b_maps != &bp->__b_map) {
191 kmem_free(bp->b_maps);
192 bp->b_maps = NULL;
193 }
194}
195
196struct xfs_buf *
197_xfs_buf_alloc(
198 struct xfs_buftarg *target,
199 struct xfs_buf_map *map,
200 int nmaps,
201 xfs_buf_flags_t flags)
202{
203 struct xfs_buf *bp;
204 int error;
205 int i;
206
207 bp = kmem_zone_zalloc(xfs_buf_zone, KM_NOFS);
208 if (unlikely(!bp))
209 return NULL;
210
211 /*
212 * We don't want certain flags to appear in b_flags unless they are
213 * specifically set by later operations on the buffer.
214 */
215 flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
216
217 atomic_set(&bp->b_hold, 1);
218 atomic_set(&bp->b_lru_ref, 1);
219 init_completion(&bp->b_iowait);
220 INIT_LIST_HEAD(&bp->b_lru);
221 INIT_LIST_HEAD(&bp->b_list);
222 sema_init(&bp->b_sema, 0); /* held, no waiters */
223 spin_lock_init(&bp->b_lock);
224 XB_SET_OWNER(bp);
225 bp->b_target = target;
226 bp->b_flags = flags;
227
228 /*
229 * Set length and io_length to the same value initially.
230 * I/O routines should use io_length, which will be the same in
231 * most cases but may be reset (e.g. XFS recovery).
232 */
233 error = xfs_buf_get_maps(bp, nmaps);
234 if (error) {
235 kmem_zone_free(xfs_buf_zone, bp);
236 return NULL;
237 }
238
239 bp->b_bn = map[0].bm_bn;
240 bp->b_length = 0;
241 for (i = 0; i < nmaps; i++) {
242 bp->b_maps[i].bm_bn = map[i].bm_bn;
243 bp->b_maps[i].bm_len = map[i].bm_len;
244 bp->b_length += map[i].bm_len;
245 }
246 bp->b_io_length = bp->b_length;
247
248 atomic_set(&bp->b_pin_count, 0);
249 init_waitqueue_head(&bp->b_waiters);
250
251 XFS_STATS_INC(target->bt_mount, xb_create);
252 trace_xfs_buf_init(bp, _RET_IP_);
253
254 return bp;
255}
256
257/*
258 * Allocate a page array capable of holding a specified number
259 * of pages, and point the page buf at it.
260 */
261STATIC int
262_xfs_buf_get_pages(
263 xfs_buf_t *bp,
264 int page_count)
265{
266 /* Make sure that we have a page list */
267 if (bp->b_pages == NULL) {
268 bp->b_page_count = page_count;
269 if (page_count <= XB_PAGES) {
270 bp->b_pages = bp->b_page_array;
271 } else {
272 bp->b_pages = kmem_alloc(sizeof(struct page *) *
273 page_count, KM_NOFS);
274 if (bp->b_pages == NULL)
275 return -ENOMEM;
276 }
277 memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
278 }
279 return 0;
280}
281
282/*
283 * Frees b_pages if it was allocated.
284 */
285STATIC void
286_xfs_buf_free_pages(
287 xfs_buf_t *bp)
288{
289 if (bp->b_pages != bp->b_page_array) {
290 kmem_free(bp->b_pages);
291 bp->b_pages = NULL;
292 }
293}
294
295/*
296 * Releases the specified buffer.
297 *
298 * The modification state of any associated pages is left unchanged.
299 * The buffer must not be on any hash - use xfs_buf_rele instead for
300 * hashed and refcounted buffers
301 */
302void
303xfs_buf_free(
304 xfs_buf_t *bp)
305{
306 trace_xfs_buf_free(bp, _RET_IP_);
307
308 ASSERT(list_empty(&bp->b_lru));
309
310 if (bp->b_flags & _XBF_PAGES) {
311 uint i;
312
313 if (xfs_buf_is_vmapped(bp))
314 vm_unmap_ram(bp->b_addr - bp->b_offset,
315 bp->b_page_count);
316
317 for (i = 0; i < bp->b_page_count; i++) {
318 struct page *page = bp->b_pages[i];
319
320 __free_page(page);
321 }
322 } else if (bp->b_flags & _XBF_KMEM)
323 kmem_free(bp->b_addr);
324 _xfs_buf_free_pages(bp);
325 xfs_buf_free_maps(bp);
326 kmem_zone_free(xfs_buf_zone, bp);
327}
328
329/*
330 * Allocates all the pages for buffer in question and builds it's page list.
331 */
332STATIC int
333xfs_buf_allocate_memory(
334 xfs_buf_t *bp,
335 uint flags)
336{
337 size_t size;
338 size_t nbytes, offset;
339 gfp_t gfp_mask = xb_to_gfp(flags);
340 unsigned short page_count, i;
341 xfs_off_t start, end;
342 int error;
343
344 /*
345 * for buffers that are contained within a single page, just allocate
346 * the memory from the heap - there's no need for the complexity of
347 * page arrays to keep allocation down to order 0.
348 */
349 size = BBTOB(bp->b_length);
350 if (size < PAGE_SIZE) {
351 bp->b_addr = kmem_alloc(size, KM_NOFS);
352 if (!bp->b_addr) {
353 /* low memory - use alloc_page loop instead */
354 goto use_alloc_page;
355 }
356
357 if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
358 ((unsigned long)bp->b_addr & PAGE_MASK)) {
359 /* b_addr spans two pages - use alloc_page instead */
360 kmem_free(bp->b_addr);
361 bp->b_addr = NULL;
362 goto use_alloc_page;
363 }
364 bp->b_offset = offset_in_page(bp->b_addr);
365 bp->b_pages = bp->b_page_array;
366 bp->b_pages[0] = virt_to_page(bp->b_addr);
367 bp->b_page_count = 1;
368 bp->b_flags |= _XBF_KMEM;
369 return 0;
370 }
371
372use_alloc_page:
373 start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT;
374 end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1)
375 >> PAGE_SHIFT;
376 page_count = end - start;
377 error = _xfs_buf_get_pages(bp, page_count);
378 if (unlikely(error))
379 return error;
380
381 offset = bp->b_offset;
382 bp->b_flags |= _XBF_PAGES;
383
384 for (i = 0; i < bp->b_page_count; i++) {
385 struct page *page;
386 uint retries = 0;
387retry:
388 page = alloc_page(gfp_mask);
389 if (unlikely(page == NULL)) {
390 if (flags & XBF_READ_AHEAD) {
391 bp->b_page_count = i;
392 error = -ENOMEM;
393 goto out_free_pages;
394 }
395
396 /*
397 * This could deadlock.
398 *
399 * But until all the XFS lowlevel code is revamped to
400 * handle buffer allocation failures we can't do much.
401 */
402 if (!(++retries % 100))
403 xfs_err(NULL,
404 "%s(%u) possible memory allocation deadlock in %s (mode:0x%x)",
405 current->comm, current->pid,
406 __func__, gfp_mask);
407
408 XFS_STATS_INC(bp->b_target->bt_mount, xb_page_retries);
409 congestion_wait(BLK_RW_ASYNC, HZ/50);
410 goto retry;
411 }
412
413 XFS_STATS_INC(bp->b_target->bt_mount, xb_page_found);
414
415 nbytes = min_t(size_t, size, PAGE_SIZE - offset);
416 size -= nbytes;
417 bp->b_pages[i] = page;
418 offset = 0;
419 }
420 return 0;
421
422out_free_pages:
423 for (i = 0; i < bp->b_page_count; i++)
424 __free_page(bp->b_pages[i]);
425 bp->b_flags &= ~_XBF_PAGES;
426 return error;
427}
428
429/*
430 * Map buffer into kernel address-space if necessary.
431 */
432STATIC int
433_xfs_buf_map_pages(
434 xfs_buf_t *bp,
435 uint flags)
436{
437 ASSERT(bp->b_flags & _XBF_PAGES);
438 if (bp->b_page_count == 1) {
439 /* A single page buffer is always mappable */
440 bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
441 } else if (flags & XBF_UNMAPPED) {
442 bp->b_addr = NULL;
443 } else {
444 int retried = 0;
445 unsigned noio_flag;
446
447 /*
448 * vm_map_ram() will allocate auxillary structures (e.g.
449 * pagetables) with GFP_KERNEL, yet we are likely to be under
450 * GFP_NOFS context here. Hence we need to tell memory reclaim
451 * that we are in such a context via PF_MEMALLOC_NOIO to prevent
452 * memory reclaim re-entering the filesystem here and
453 * potentially deadlocking.
454 */
455 noio_flag = memalloc_noio_save();
456 do {
457 bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
458 -1, PAGE_KERNEL);
459 if (bp->b_addr)
460 break;
461 vm_unmap_aliases();
462 } while (retried++ <= 1);
463 memalloc_noio_restore(noio_flag);
464
465 if (!bp->b_addr)
466 return -ENOMEM;
467 bp->b_addr += bp->b_offset;
468 }
469
470 return 0;
471}
472
473/*
474 * Finding and Reading Buffers
475 */
476static int
477_xfs_buf_obj_cmp(
478 struct rhashtable_compare_arg *arg,
479 const void *obj)
480{
481 const struct xfs_buf_map *map = arg->key;
482 const struct xfs_buf *bp = obj;
483
484 /*
485 * The key hashing in the lookup path depends on the key being the
486 * first element of the compare_arg, make sure to assert this.
487 */
488 BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
489
490 if (bp->b_bn != map->bm_bn)
491 return 1;
492
493 if (unlikely(bp->b_length != map->bm_len)) {
494 /*
495 * found a block number match. If the range doesn't
496 * match, the only way this is allowed is if the buffer
497 * in the cache is stale and the transaction that made
498 * it stale has not yet committed. i.e. we are
499 * reallocating a busy extent. Skip this buffer and
500 * continue searching for an exact match.
501 */
502 ASSERT(bp->b_flags & XBF_STALE);
503 return 1;
504 }
505 return 0;
506}
507
508static const struct rhashtable_params xfs_buf_hash_params = {
509 .min_size = 32, /* empty AGs have minimal footprint */
510 .nelem_hint = 16,
511 .key_len = sizeof(xfs_daddr_t),
512 .key_offset = offsetof(struct xfs_buf, b_bn),
513 .head_offset = offsetof(struct xfs_buf, b_rhash_head),
514 .automatic_shrinking = true,
515 .obj_cmpfn = _xfs_buf_obj_cmp,
516};
517
518int
519xfs_buf_hash_init(
520 struct xfs_perag *pag)
521{
522 spin_lock_init(&pag->pag_buf_lock);
523 return rhashtable_init(&pag->pag_buf_hash, &xfs_buf_hash_params);
524}
525
526void
527xfs_buf_hash_destroy(
528 struct xfs_perag *pag)
529{
530 rhashtable_destroy(&pag->pag_buf_hash);
531}
532
533/*
534 * Look up, and creates if absent, a lockable buffer for
535 * a given range of an inode. The buffer is returned
536 * locked. No I/O is implied by this call.
537 */
538xfs_buf_t *
539_xfs_buf_find(
540 struct xfs_buftarg *btp,
541 struct xfs_buf_map *map,
542 int nmaps,
543 xfs_buf_flags_t flags,
544 xfs_buf_t *new_bp)
545{
546 struct xfs_perag *pag;
547 xfs_buf_t *bp;
548 struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };
549 xfs_daddr_t eofs;
550 int i;
551
552 for (i = 0; i < nmaps; i++)
553 cmap.bm_len += map[i].bm_len;
554
555 /* Check for IOs smaller than the sector size / not sector aligned */
556 ASSERT(!(BBTOB(cmap.bm_len) < btp->bt_meta_sectorsize));
557 ASSERT(!(BBTOB(cmap.bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
558
559 /*
560 * Corrupted block numbers can get through to here, unfortunately, so we
561 * have to check that the buffer falls within the filesystem bounds.
562 */
563 eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
564 if (cmap.bm_bn < 0 || cmap.bm_bn >= eofs) {
565 /*
566 * XXX (dgc): we should really be returning -EFSCORRUPTED here,
567 * but none of the higher level infrastructure supports
568 * returning a specific error on buffer lookup failures.
569 */
570 xfs_alert(btp->bt_mount,
571 "%s: Block out of range: block 0x%llx, EOFS 0x%llx ",
572 __func__, cmap.bm_bn, eofs);
573 WARN_ON(1);
574 return NULL;
575 }
576
577 pag = xfs_perag_get(btp->bt_mount,
578 xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
579
580 spin_lock(&pag->pag_buf_lock);
581 bp = rhashtable_lookup_fast(&pag->pag_buf_hash, &cmap,
582 xfs_buf_hash_params);
583 if (bp) {
584 atomic_inc(&bp->b_hold);
585 goto found;
586 }
587
588 /* No match found */
589 if (new_bp) {
590 /* the buffer keeps the perag reference until it is freed */
591 new_bp->b_pag = pag;
592 rhashtable_insert_fast(&pag->pag_buf_hash,
593 &new_bp->b_rhash_head,
594 xfs_buf_hash_params);
595 spin_unlock(&pag->pag_buf_lock);
596 } else {
597 XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
598 spin_unlock(&pag->pag_buf_lock);
599 xfs_perag_put(pag);
600 }
601 return new_bp;
602
603found:
604 spin_unlock(&pag->pag_buf_lock);
605 xfs_perag_put(pag);
606
607 if (!xfs_buf_trylock(bp)) {
608 if (flags & XBF_TRYLOCK) {
609 xfs_buf_rele(bp);
610 XFS_STATS_INC(btp->bt_mount, xb_busy_locked);
611 return NULL;
612 }
613 xfs_buf_lock(bp);
614 XFS_STATS_INC(btp->bt_mount, xb_get_locked_waited);
615 }
616
617 /*
618 * if the buffer is stale, clear all the external state associated with
619 * it. We need to keep flags such as how we allocated the buffer memory
620 * intact here.
621 */
622 if (bp->b_flags & XBF_STALE) {
623 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
624 ASSERT(bp->b_iodone == NULL);
625 bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
626 bp->b_ops = NULL;
627 }
628
629 trace_xfs_buf_find(bp, flags, _RET_IP_);
630 XFS_STATS_INC(btp->bt_mount, xb_get_locked);
631 return bp;
632}
633
634/*
635 * Assembles a buffer covering the specified range. The code is optimised for
636 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
637 * more hits than misses.
638 */
639struct xfs_buf *
640xfs_buf_get_map(
641 struct xfs_buftarg *target,
642 struct xfs_buf_map *map,
643 int nmaps,
644 xfs_buf_flags_t flags)
645{
646 struct xfs_buf *bp;
647 struct xfs_buf *new_bp;
648 int error = 0;
649
650 bp = _xfs_buf_find(target, map, nmaps, flags, NULL);
651 if (likely(bp))
652 goto found;
653
654 new_bp = _xfs_buf_alloc(target, map, nmaps, flags);
655 if (unlikely(!new_bp))
656 return NULL;
657
658 error = xfs_buf_allocate_memory(new_bp, flags);
659 if (error) {
660 xfs_buf_free(new_bp);
661 return NULL;
662 }
663
664 bp = _xfs_buf_find(target, map, nmaps, flags, new_bp);
665 if (!bp) {
666 xfs_buf_free(new_bp);
667 return NULL;
668 }
669
670 if (bp != new_bp)
671 xfs_buf_free(new_bp);
672
673found:
674 if (!bp->b_addr) {
675 error = _xfs_buf_map_pages(bp, flags);
676 if (unlikely(error)) {
677 xfs_warn(target->bt_mount,
678 "%s: failed to map pagesn", __func__);
679 xfs_buf_relse(bp);
680 return NULL;
681 }
682 }
683
684 /*
685 * Clear b_error if this is a lookup from a caller that doesn't expect
686 * valid data to be found in the buffer.
687 */
688 if (!(flags & XBF_READ))
689 xfs_buf_ioerror(bp, 0);
690
691 XFS_STATS_INC(target->bt_mount, xb_get);
692 trace_xfs_buf_get(bp, flags, _RET_IP_);
693 return bp;
694}
695
696STATIC int
697_xfs_buf_read(
698 xfs_buf_t *bp,
699 xfs_buf_flags_t flags)
700{
701 ASSERT(!(flags & XBF_WRITE));
702 ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
703
704 bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD);
705 bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
706
707 if (flags & XBF_ASYNC) {
708 xfs_buf_submit(bp);
709 return 0;
710 }
711 return xfs_buf_submit_wait(bp);
712}
713
714xfs_buf_t *
715xfs_buf_read_map(
716 struct xfs_buftarg *target,
717 struct xfs_buf_map *map,
718 int nmaps,
719 xfs_buf_flags_t flags,
720 const struct xfs_buf_ops *ops)
721{
722 struct xfs_buf *bp;
723
724 flags |= XBF_READ;
725
726 bp = xfs_buf_get_map(target, map, nmaps, flags);
727 if (bp) {
728 trace_xfs_buf_read(bp, flags, _RET_IP_);
729
730 if (!(bp->b_flags & XBF_DONE)) {
731 XFS_STATS_INC(target->bt_mount, xb_get_read);
732 bp->b_ops = ops;
733 _xfs_buf_read(bp, flags);
734 } else if (flags & XBF_ASYNC) {
735 /*
736 * Read ahead call which is already satisfied,
737 * drop the buffer
738 */
739 xfs_buf_relse(bp);
740 return NULL;
741 } else {
742 /* We do not want read in the flags */
743 bp->b_flags &= ~XBF_READ;
744 }
745 }
746
747 return bp;
748}
749
750/*
751 * If we are not low on memory then do the readahead in a deadlock
752 * safe manner.
753 */
754void
755xfs_buf_readahead_map(
756 struct xfs_buftarg *target,
757 struct xfs_buf_map *map,
758 int nmaps,
759 const struct xfs_buf_ops *ops)
760{
761 if (bdi_read_congested(target->bt_bdi))
762 return;
763
764 xfs_buf_read_map(target, map, nmaps,
765 XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, ops);
766}
767
768/*
769 * Read an uncached buffer from disk. Allocates and returns a locked
770 * buffer containing the disk contents or nothing.
771 */
772int
773xfs_buf_read_uncached(
774 struct xfs_buftarg *target,
775 xfs_daddr_t daddr,
776 size_t numblks,
777 int flags,
778 struct xfs_buf **bpp,
779 const struct xfs_buf_ops *ops)
780{
781 struct xfs_buf *bp;
782
783 *bpp = NULL;
784
785 bp = xfs_buf_get_uncached(target, numblks, flags);
786 if (!bp)
787 return -ENOMEM;
788
789 /* set up the buffer for a read IO */
790 ASSERT(bp->b_map_count == 1);
791 bp->b_bn = XFS_BUF_DADDR_NULL; /* always null for uncached buffers */
792 bp->b_maps[0].bm_bn = daddr;
793 bp->b_flags |= XBF_READ;
794 bp->b_ops = ops;
795
796 xfs_buf_submit_wait(bp);
797 if (bp->b_error) {
798 int error = bp->b_error;
799 xfs_buf_relse(bp);
800 return error;
801 }
802
803 *bpp = bp;
804 return 0;
805}
806
807/*
808 * Return a buffer allocated as an empty buffer and associated to external
809 * memory via xfs_buf_associate_memory() back to it's empty state.
810 */
811void
812xfs_buf_set_empty(
813 struct xfs_buf *bp,
814 size_t numblks)
815{
816 if (bp->b_pages)
817 _xfs_buf_free_pages(bp);
818
819 bp->b_pages = NULL;
820 bp->b_page_count = 0;
821 bp->b_addr = NULL;
822 bp->b_length = numblks;
823 bp->b_io_length = numblks;
824
825 ASSERT(bp->b_map_count == 1);
826 bp->b_bn = XFS_BUF_DADDR_NULL;
827 bp->b_maps[0].bm_bn = XFS_BUF_DADDR_NULL;
828 bp->b_maps[0].bm_len = bp->b_length;
829}
830
831static inline struct page *
832mem_to_page(
833 void *addr)
834{
835 if ((!is_vmalloc_addr(addr))) {
836 return virt_to_page(addr);
837 } else {
838 return vmalloc_to_page(addr);
839 }
840}
841
842int
843xfs_buf_associate_memory(
844 xfs_buf_t *bp,
845 void *mem,
846 size_t len)
847{
848 int rval;
849 int i = 0;
850 unsigned long pageaddr;
851 unsigned long offset;
852 size_t buflen;
853 int page_count;
854
855 pageaddr = (unsigned long)mem & PAGE_MASK;
856 offset = (unsigned long)mem - pageaddr;
857 buflen = PAGE_ALIGN(len + offset);
858 page_count = buflen >> PAGE_SHIFT;
859
860 /* Free any previous set of page pointers */
861 if (bp->b_pages)
862 _xfs_buf_free_pages(bp);
863
864 bp->b_pages = NULL;
865 bp->b_addr = mem;
866
867 rval = _xfs_buf_get_pages(bp, page_count);
868 if (rval)
869 return rval;
870
871 bp->b_offset = offset;
872
873 for (i = 0; i < bp->b_page_count; i++) {
874 bp->b_pages[i] = mem_to_page((void *)pageaddr);
875 pageaddr += PAGE_SIZE;
876 }
877
878 bp->b_io_length = BTOBB(len);
879 bp->b_length = BTOBB(buflen);
880
881 return 0;
882}
883
884xfs_buf_t *
885xfs_buf_get_uncached(
886 struct xfs_buftarg *target,
887 size_t numblks,
888 int flags)
889{
890 unsigned long page_count;
891 int error, i;
892 struct xfs_buf *bp;
893 DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
894
895 /* flags might contain irrelevant bits, pass only what we care about */
896 bp = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT);
897 if (unlikely(bp == NULL))
898 goto fail;
899
900 page_count = PAGE_ALIGN(numblks << BBSHIFT) >> PAGE_SHIFT;
901 error = _xfs_buf_get_pages(bp, page_count);
902 if (error)
903 goto fail_free_buf;
904
905 for (i = 0; i < page_count; i++) {
906 bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
907 if (!bp->b_pages[i])
908 goto fail_free_mem;
909 }
910 bp->b_flags |= _XBF_PAGES;
911
912 error = _xfs_buf_map_pages(bp, 0);
913 if (unlikely(error)) {
914 xfs_warn(target->bt_mount,
915 "%s: failed to map pages", __func__);
916 goto fail_free_mem;
917 }
918
919 trace_xfs_buf_get_uncached(bp, _RET_IP_);
920 return bp;
921
922 fail_free_mem:
923 while (--i >= 0)
924 __free_page(bp->b_pages[i]);
925 _xfs_buf_free_pages(bp);
926 fail_free_buf:
927 xfs_buf_free_maps(bp);
928 kmem_zone_free(xfs_buf_zone, bp);
929 fail:
930 return NULL;
931}
932
933/*
934 * Increment reference count on buffer, to hold the buffer concurrently
935 * with another thread which may release (free) the buffer asynchronously.
936 * Must hold the buffer already to call this function.
937 */
938void
939xfs_buf_hold(
940 xfs_buf_t *bp)
941{
942 trace_xfs_buf_hold(bp, _RET_IP_);
943 atomic_inc(&bp->b_hold);
944}
945
946/*
947 * Release a hold on the specified buffer. If the hold count is 1, the buffer is
948 * placed on LRU or freed (depending on b_lru_ref).
949 */
950void
951xfs_buf_rele(
952 xfs_buf_t *bp)
953{
954 struct xfs_perag *pag = bp->b_pag;
955 bool release;
956 bool freebuf = false;
957
958 trace_xfs_buf_rele(bp, _RET_IP_);
959
960 if (!pag) {
961 ASSERT(list_empty(&bp->b_lru));
962 if (atomic_dec_and_test(&bp->b_hold)) {
963 xfs_buf_ioacct_dec(bp);
964 xfs_buf_free(bp);
965 }
966 return;
967 }
968
969 ASSERT(atomic_read(&bp->b_hold) > 0);
970
971 release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock);
972 spin_lock(&bp->b_lock);
973 if (!release) {
974 /*
975 * Drop the in-flight state if the buffer is already on the LRU
976 * and it holds the only reference. This is racy because we
977 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
978 * ensures the decrement occurs only once per-buf.
979 */
980 if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))
981 xfs_buf_ioacct_dec(bp);
982 goto out_unlock;
983 }
984
985 /* the last reference has been dropped ... */
986 xfs_buf_ioacct_dec(bp);
987 if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
988 /*
989 * If the buffer is added to the LRU take a new reference to the
990 * buffer for the LRU and clear the (now stale) dispose list
991 * state flag
992 */
993 if (list_lru_add(&bp->b_target->bt_lru, &bp->b_lru)) {
994 bp->b_state &= ~XFS_BSTATE_DISPOSE;
995 atomic_inc(&bp->b_hold);
996 }
997 spin_unlock(&pag->pag_buf_lock);
998 } else {
999 /*
1000 * most of the time buffers will already be removed from the
1001 * LRU, so optimise that case by checking for the
1002 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1003 * was on was the disposal list
1004 */
1005 if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
1006 list_lru_del(&bp->b_target->bt_lru, &bp->b_lru);
1007 } else {
1008 ASSERT(list_empty(&bp->b_lru));
1009 }
1010
1011 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1012 rhashtable_remove_fast(&pag->pag_buf_hash, &bp->b_rhash_head,
1013 xfs_buf_hash_params);
1014 spin_unlock(&pag->pag_buf_lock);
1015 xfs_perag_put(pag);
1016 freebuf = true;
1017 }
1018
1019out_unlock:
1020 spin_unlock(&bp->b_lock);
1021
1022 if (freebuf)
1023 xfs_buf_free(bp);
1024}
1025
1026
1027/*
1028 * Lock a buffer object, if it is not already locked.
1029 *
1030 * If we come across a stale, pinned, locked buffer, we know that we are
1031 * being asked to lock a buffer that has been reallocated. Because it is
1032 * pinned, we know that the log has not been pushed to disk and hence it
1033 * will still be locked. Rather than continuing to have trylock attempts
1034 * fail until someone else pushes the log, push it ourselves before
1035 * returning. This means that the xfsaild will not get stuck trying
1036 * to push on stale inode buffers.
1037 */
1038int
1039xfs_buf_trylock(
1040 struct xfs_buf *bp)
1041{
1042 int locked;
1043
1044 locked = down_trylock(&bp->b_sema) == 0;
1045 if (locked) {
1046 XB_SET_OWNER(bp);
1047 trace_xfs_buf_trylock(bp, _RET_IP_);
1048 } else {
1049 trace_xfs_buf_trylock_fail(bp, _RET_IP_);
1050 }
1051 return locked;
1052}
1053
1054/*
1055 * Lock a buffer object.
1056 *
1057 * If we come across a stale, pinned, locked buffer, we know that we
1058 * are being asked to lock a buffer that has been reallocated. Because
1059 * it is pinned, we know that the log has not been pushed to disk and
1060 * hence it will still be locked. Rather than sleeping until someone
1061 * else pushes the log, push it ourselves before trying to get the lock.
1062 */
1063void
1064xfs_buf_lock(
1065 struct xfs_buf *bp)
1066{
1067 trace_xfs_buf_lock(bp, _RET_IP_);
1068
1069 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
1070 xfs_log_force(bp->b_target->bt_mount, 0);
1071 down(&bp->b_sema);
1072 XB_SET_OWNER(bp);
1073
1074 trace_xfs_buf_lock_done(bp, _RET_IP_);
1075}
1076
1077void
1078xfs_buf_unlock(
1079 struct xfs_buf *bp)
1080{
1081 XB_CLEAR_OWNER(bp);
1082 up(&bp->b_sema);
1083
1084 trace_xfs_buf_unlock(bp, _RET_IP_);
1085}
1086
1087STATIC void
1088xfs_buf_wait_unpin(
1089 xfs_buf_t *bp)
1090{
1091 DECLARE_WAITQUEUE (wait, current);
1092
1093 if (atomic_read(&bp->b_pin_count) == 0)
1094 return;
1095
1096 add_wait_queue(&bp->b_waiters, &wait);
1097 for (;;) {
1098 set_current_state(TASK_UNINTERRUPTIBLE);
1099 if (atomic_read(&bp->b_pin_count) == 0)
1100 break;
1101 io_schedule();
1102 }
1103 remove_wait_queue(&bp->b_waiters, &wait);
1104 set_current_state(TASK_RUNNING);
1105}
1106
1107/*
1108 * Buffer Utility Routines
1109 */
1110
1111void
1112xfs_buf_ioend(
1113 struct xfs_buf *bp)
1114{
1115 bool read = bp->b_flags & XBF_READ;
1116
1117 trace_xfs_buf_iodone(bp, _RET_IP_);
1118
1119 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
1120
1121 /*
1122 * Pull in IO completion errors now. We are guaranteed to be running
1123 * single threaded, so we don't need the lock to read b_io_error.
1124 */
1125 if (!bp->b_error && bp->b_io_error)
1126 xfs_buf_ioerror(bp, bp->b_io_error);
1127
1128 /* Only validate buffers that were read without errors */
1129 if (read && !bp->b_error && bp->b_ops) {
1130 ASSERT(!bp->b_iodone);
1131 bp->b_ops->verify_read(bp);
1132 }
1133
1134 if (!bp->b_error)
1135 bp->b_flags |= XBF_DONE;
1136
1137 if (bp->b_iodone)
1138 (*(bp->b_iodone))(bp);
1139 else if (bp->b_flags & XBF_ASYNC)
1140 xfs_buf_relse(bp);
1141 else
1142 complete(&bp->b_iowait);
1143}
1144
1145static void
1146xfs_buf_ioend_work(
1147 struct work_struct *work)
1148{
1149 struct xfs_buf *bp =
1150 container_of(work, xfs_buf_t, b_ioend_work);
1151
1152 xfs_buf_ioend(bp);
1153}
1154
1155static void
1156xfs_buf_ioend_async(
1157 struct xfs_buf *bp)
1158{
1159 INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
1160 queue_work(bp->b_ioend_wq, &bp->b_ioend_work);
1161}
1162
1163void
1164xfs_buf_ioerror(
1165 xfs_buf_t *bp,
1166 int error)
1167{
1168 ASSERT(error <= 0 && error >= -1000);
1169 bp->b_error = error;
1170 trace_xfs_buf_ioerror(bp, error, _RET_IP_);
1171}
1172
1173void
1174xfs_buf_ioerror_alert(
1175 struct xfs_buf *bp,
1176 const char *func)
1177{
1178 xfs_alert(bp->b_target->bt_mount,
1179"metadata I/O error: block 0x%llx (\"%s\") error %d numblks %d",
1180 (__uint64_t)XFS_BUF_ADDR(bp), func, -bp->b_error, bp->b_length);
1181}
1182
1183int
1184xfs_bwrite(
1185 struct xfs_buf *bp)
1186{
1187 int error;
1188
1189 ASSERT(xfs_buf_islocked(bp));
1190
1191 bp->b_flags |= XBF_WRITE;
1192 bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
1193 XBF_WRITE_FAIL | XBF_DONE);
1194
1195 error = xfs_buf_submit_wait(bp);
1196 if (error) {
1197 xfs_force_shutdown(bp->b_target->bt_mount,
1198 SHUTDOWN_META_IO_ERROR);
1199 }
1200 return error;
1201}
1202
1203static void
1204xfs_buf_bio_end_io(
1205 struct bio *bio)
1206{
1207 struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private;
1208
1209 /*
1210 * don't overwrite existing errors - otherwise we can lose errors on
1211 * buffers that require multiple bios to complete.
1212 */
1213 if (bio->bi_error)
1214 cmpxchg(&bp->b_io_error, 0, bio->bi_error);
1215
1216 if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1217 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1218
1219 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1220 xfs_buf_ioend_async(bp);
1221 bio_put(bio);
1222}
1223
1224static void
1225xfs_buf_ioapply_map(
1226 struct xfs_buf *bp,
1227 int map,
1228 int *buf_offset,
1229 int *count,
1230 int op,
1231 int op_flags)
1232{
1233 int page_index;
1234 int total_nr_pages = bp->b_page_count;
1235 int nr_pages;
1236 struct bio *bio;
1237 sector_t sector = bp->b_maps[map].bm_bn;
1238 int size;
1239 int offset;
1240
1241 total_nr_pages = bp->b_page_count;
1242
1243 /* skip the pages in the buffer before the start offset */
1244 page_index = 0;
1245 offset = *buf_offset;
1246 while (offset >= PAGE_SIZE) {
1247 page_index++;
1248 offset -= PAGE_SIZE;
1249 }
1250
1251 /*
1252 * Limit the IO size to the length of the current vector, and update the
1253 * remaining IO count for the next time around.
1254 */
1255 size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1256 *count -= size;
1257 *buf_offset += size;
1258
1259next_chunk:
1260 atomic_inc(&bp->b_io_remaining);
1261 nr_pages = min(total_nr_pages, BIO_MAX_PAGES);
1262
1263 bio = bio_alloc(GFP_NOIO, nr_pages);
1264 bio->bi_bdev = bp->b_target->bt_bdev;
1265 bio->bi_iter.bi_sector = sector;
1266 bio->bi_end_io = xfs_buf_bio_end_io;
1267 bio->bi_private = bp;
1268 bio_set_op_attrs(bio, op, op_flags);
1269
1270 for (; size && nr_pages; nr_pages--, page_index++) {
1271 int rbytes, nbytes = PAGE_SIZE - offset;
1272
1273 if (nbytes > size)
1274 nbytes = size;
1275
1276 rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
1277 offset);
1278 if (rbytes < nbytes)
1279 break;
1280
1281 offset = 0;
1282 sector += BTOBB(nbytes);
1283 size -= nbytes;
1284 total_nr_pages--;
1285 }
1286
1287 if (likely(bio->bi_iter.bi_size)) {
1288 if (xfs_buf_is_vmapped(bp)) {
1289 flush_kernel_vmap_range(bp->b_addr,
1290 xfs_buf_vmap_len(bp));
1291 }
1292 submit_bio(bio);
1293 if (size)
1294 goto next_chunk;
1295 } else {
1296 /*
1297 * This is guaranteed not to be the last io reference count
1298 * because the caller (xfs_buf_submit) holds a count itself.
1299 */
1300 atomic_dec(&bp->b_io_remaining);
1301 xfs_buf_ioerror(bp, -EIO);
1302 bio_put(bio);
1303 }
1304
1305}
1306
1307STATIC void
1308_xfs_buf_ioapply(
1309 struct xfs_buf *bp)
1310{
1311 struct blk_plug plug;
1312 int op;
1313 int op_flags = 0;
1314 int offset;
1315 int size;
1316 int i;
1317
1318 /*
1319 * Make sure we capture only current IO errors rather than stale errors
1320 * left over from previous use of the buffer (e.g. failed readahead).
1321 */
1322 bp->b_error = 0;
1323
1324 /*
1325 * Initialize the I/O completion workqueue if we haven't yet or the
1326 * submitter has not opted to specify a custom one.
1327 */
1328 if (!bp->b_ioend_wq)
1329 bp->b_ioend_wq = bp->b_target->bt_mount->m_buf_workqueue;
1330
1331 if (bp->b_flags & XBF_WRITE) {
1332 op = REQ_OP_WRITE;
1333 if (bp->b_flags & XBF_SYNCIO)
1334 op_flags = REQ_SYNC;
1335 if (bp->b_flags & XBF_FUA)
1336 op_flags |= REQ_FUA;
1337 if (bp->b_flags & XBF_FLUSH)
1338 op_flags |= REQ_PREFLUSH;
1339
1340 /*
1341 * Run the write verifier callback function if it exists. If
1342 * this function fails it will mark the buffer with an error and
1343 * the IO should not be dispatched.
1344 */
1345 if (bp->b_ops) {
1346 bp->b_ops->verify_write(bp);
1347 if (bp->b_error) {
1348 xfs_force_shutdown(bp->b_target->bt_mount,
1349 SHUTDOWN_CORRUPT_INCORE);
1350 return;
1351 }
1352 } else if (bp->b_bn != XFS_BUF_DADDR_NULL) {
1353 struct xfs_mount *mp = bp->b_target->bt_mount;
1354
1355 /*
1356 * non-crc filesystems don't attach verifiers during
1357 * log recovery, so don't warn for such filesystems.
1358 */
1359 if (xfs_sb_version_hascrc(&mp->m_sb)) {
1360 xfs_warn(mp,
1361 "%s: no ops on block 0x%llx/0x%x",
1362 __func__, bp->b_bn, bp->b_length);
1363 xfs_hex_dump(bp->b_addr, 64);
1364 dump_stack();
1365 }
1366 }
1367 } else if (bp->b_flags & XBF_READ_AHEAD) {
1368 op = REQ_OP_READ;
1369 op_flags = REQ_RAHEAD;
1370 } else {
1371 op = REQ_OP_READ;
1372 }
1373
1374 /* we only use the buffer cache for meta-data */
1375 op_flags |= REQ_META;
1376
1377 /*
1378 * Walk all the vectors issuing IO on them. Set up the initial offset
1379 * into the buffer and the desired IO size before we start -
1380 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1381 * subsequent call.
1382 */
1383 offset = bp->b_offset;
1384 size = BBTOB(bp->b_io_length);
1385 blk_start_plug(&plug);
1386 for (i = 0; i < bp->b_map_count; i++) {
1387 xfs_buf_ioapply_map(bp, i, &offset, &size, op, op_flags);
1388 if (bp->b_error)
1389 break;
1390 if (size <= 0)
1391 break; /* all done */
1392 }
1393 blk_finish_plug(&plug);
1394}
1395
1396/*
1397 * Asynchronous IO submission path. This transfers the buffer lock ownership and
1398 * the current reference to the IO. It is not safe to reference the buffer after
1399 * a call to this function unless the caller holds an additional reference
1400 * itself.
1401 */
1402void
1403xfs_buf_submit(
1404 struct xfs_buf *bp)
1405{
1406 trace_xfs_buf_submit(bp, _RET_IP_);
1407
1408 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1409 ASSERT(bp->b_flags & XBF_ASYNC);
1410
1411 /* on shutdown we stale and complete the buffer immediately */
1412 if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
1413 xfs_buf_ioerror(bp, -EIO);
1414 bp->b_flags &= ~XBF_DONE;
1415 xfs_buf_stale(bp);
1416 xfs_buf_ioend(bp);
1417 return;
1418 }
1419
1420 if (bp->b_flags & XBF_WRITE)
1421 xfs_buf_wait_unpin(bp);
1422
1423 /* clear the internal error state to avoid spurious errors */
1424 bp->b_io_error = 0;
1425
1426 /*
1427 * The caller's reference is released during I/O completion.
1428 * This occurs some time after the last b_io_remaining reference is
1429 * released, so after we drop our Io reference we have to have some
1430 * other reference to ensure the buffer doesn't go away from underneath
1431 * us. Take a direct reference to ensure we have safe access to the
1432 * buffer until we are finished with it.
1433 */
1434 xfs_buf_hold(bp);
1435
1436 /*
1437 * Set the count to 1 initially, this will stop an I/O completion
1438 * callout which happens before we have started all the I/O from calling
1439 * xfs_buf_ioend too early.
1440 */
1441 atomic_set(&bp->b_io_remaining, 1);
1442 xfs_buf_ioacct_inc(bp);
1443 _xfs_buf_ioapply(bp);
1444
1445 /*
1446 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1447 * reference we took above. If we drop it to zero, run completion so
1448 * that we don't return to the caller with completion still pending.
1449 */
1450 if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1451 if (bp->b_error)
1452 xfs_buf_ioend(bp);
1453 else
1454 xfs_buf_ioend_async(bp);
1455 }
1456
1457 xfs_buf_rele(bp);
1458 /* Note: it is not safe to reference bp now we've dropped our ref */
1459}
1460
1461/*
1462 * Synchronous buffer IO submission path, read or write.
1463 */
1464int
1465xfs_buf_submit_wait(
1466 struct xfs_buf *bp)
1467{
1468 int error;
1469
1470 trace_xfs_buf_submit_wait(bp, _RET_IP_);
1471
1472 ASSERT(!(bp->b_flags & (_XBF_DELWRI_Q | XBF_ASYNC)));
1473
1474 if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
1475 xfs_buf_ioerror(bp, -EIO);
1476 xfs_buf_stale(bp);
1477 bp->b_flags &= ~XBF_DONE;
1478 return -EIO;
1479 }
1480
1481 if (bp->b_flags & XBF_WRITE)
1482 xfs_buf_wait_unpin(bp);
1483
1484 /* clear the internal error state to avoid spurious errors */
1485 bp->b_io_error = 0;
1486
1487 /*
1488 * For synchronous IO, the IO does not inherit the submitters reference
1489 * count, nor the buffer lock. Hence we cannot release the reference we
1490 * are about to take until we've waited for all IO completion to occur,
1491 * including any xfs_buf_ioend_async() work that may be pending.
1492 */
1493 xfs_buf_hold(bp);
1494
1495 /*
1496 * Set the count to 1 initially, this will stop an I/O completion
1497 * callout which happens before we have started all the I/O from calling
1498 * xfs_buf_ioend too early.
1499 */
1500 atomic_set(&bp->b_io_remaining, 1);
1501 _xfs_buf_ioapply(bp);
1502
1503 /*
1504 * make sure we run completion synchronously if it raced with us and is
1505 * already complete.
1506 */
1507 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1508 xfs_buf_ioend(bp);
1509
1510 /* wait for completion before gathering the error from the buffer */
1511 trace_xfs_buf_iowait(bp, _RET_IP_);
1512 wait_for_completion(&bp->b_iowait);
1513 trace_xfs_buf_iowait_done(bp, _RET_IP_);
1514 error = bp->b_error;
1515
1516 /*
1517 * all done now, we can release the hold that keeps the buffer
1518 * referenced for the entire IO.
1519 */
1520 xfs_buf_rele(bp);
1521 return error;
1522}
1523
1524void *
1525xfs_buf_offset(
1526 struct xfs_buf *bp,
1527 size_t offset)
1528{
1529 struct page *page;
1530
1531 if (bp->b_addr)
1532 return bp->b_addr + offset;
1533
1534 offset += bp->b_offset;
1535 page = bp->b_pages[offset >> PAGE_SHIFT];
1536 return page_address(page) + (offset & (PAGE_SIZE-1));
1537}
1538
1539/*
1540 * Move data into or out of a buffer.
1541 */
1542void
1543xfs_buf_iomove(
1544 xfs_buf_t *bp, /* buffer to process */
1545 size_t boff, /* starting buffer offset */
1546 size_t bsize, /* length to copy */
1547 void *data, /* data address */
1548 xfs_buf_rw_t mode) /* read/write/zero flag */
1549{
1550 size_t bend;
1551
1552 bend = boff + bsize;
1553 while (boff < bend) {
1554 struct page *page;
1555 int page_index, page_offset, csize;
1556
1557 page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1558 page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1559 page = bp->b_pages[page_index];
1560 csize = min_t(size_t, PAGE_SIZE - page_offset,
1561 BBTOB(bp->b_io_length) - boff);
1562
1563 ASSERT((csize + page_offset) <= PAGE_SIZE);
1564
1565 switch (mode) {
1566 case XBRW_ZERO:
1567 memset(page_address(page) + page_offset, 0, csize);
1568 break;
1569 case XBRW_READ:
1570 memcpy(data, page_address(page) + page_offset, csize);
1571 break;
1572 case XBRW_WRITE:
1573 memcpy(page_address(page) + page_offset, data, csize);
1574 }
1575
1576 boff += csize;
1577 data += csize;
1578 }
1579}
1580
1581/*
1582 * Handling of buffer targets (buftargs).
1583 */
1584
1585/*
1586 * Wait for any bufs with callbacks that have been submitted but have not yet
1587 * returned. These buffers will have an elevated hold count, so wait on those
1588 * while freeing all the buffers only held by the LRU.
1589 */
1590static enum lru_status
1591xfs_buftarg_wait_rele(
1592 struct list_head *item,
1593 struct list_lru_one *lru,
1594 spinlock_t *lru_lock,
1595 void *arg)
1596
1597{
1598 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1599 struct list_head *dispose = arg;
1600
1601 if (atomic_read(&bp->b_hold) > 1) {
1602 /* need to wait, so skip it this pass */
1603 trace_xfs_buf_wait_buftarg(bp, _RET_IP_);
1604 return LRU_SKIP;
1605 }
1606 if (!spin_trylock(&bp->b_lock))
1607 return LRU_SKIP;
1608
1609 /*
1610 * clear the LRU reference count so the buffer doesn't get
1611 * ignored in xfs_buf_rele().
1612 */
1613 atomic_set(&bp->b_lru_ref, 0);
1614 bp->b_state |= XFS_BSTATE_DISPOSE;
1615 list_lru_isolate_move(lru, item, dispose);
1616 spin_unlock(&bp->b_lock);
1617 return LRU_REMOVED;
1618}
1619
1620void
1621xfs_wait_buftarg(
1622 struct xfs_buftarg *btp)
1623{
1624 LIST_HEAD(dispose);
1625 int loop = 0;
1626
1627 /*
1628 * First wait on the buftarg I/O count for all in-flight buffers to be
1629 * released. This is critical as new buffers do not make the LRU until
1630 * they are released.
1631 *
1632 * Next, flush the buffer workqueue to ensure all completion processing
1633 * has finished. Just waiting on buffer locks is not sufficient for
1634 * async IO as the reference count held over IO is not released until
1635 * after the buffer lock is dropped. Hence we need to ensure here that
1636 * all reference counts have been dropped before we start walking the
1637 * LRU list.
1638 */
1639 while (percpu_counter_sum(&btp->bt_io_count))
1640 delay(100);
1641 flush_workqueue(btp->bt_mount->m_buf_workqueue);
1642
1643 /* loop until there is nothing left on the lru list. */
1644 while (list_lru_count(&btp->bt_lru)) {
1645 list_lru_walk(&btp->bt_lru, xfs_buftarg_wait_rele,
1646 &dispose, LONG_MAX);
1647
1648 while (!list_empty(&dispose)) {
1649 struct xfs_buf *bp;
1650 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1651 list_del_init(&bp->b_lru);
1652 if (bp->b_flags & XBF_WRITE_FAIL) {
1653 xfs_alert(btp->bt_mount,
1654"Corruption Alert: Buffer at block 0x%llx had permanent write failures!",
1655 (long long)bp->b_bn);
1656 xfs_alert(btp->bt_mount,
1657"Please run xfs_repair to determine the extent of the problem.");
1658 }
1659 xfs_buf_rele(bp);
1660 }
1661 if (loop++ != 0)
1662 delay(100);
1663 }
1664}
1665
1666static enum lru_status
1667xfs_buftarg_isolate(
1668 struct list_head *item,
1669 struct list_lru_one *lru,
1670 spinlock_t *lru_lock,
1671 void *arg)
1672{
1673 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1674 struct list_head *dispose = arg;
1675
1676 /*
1677 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1678 * If we fail to get the lock, just skip it.
1679 */
1680 if (!spin_trylock(&bp->b_lock))
1681 return LRU_SKIP;
1682 /*
1683 * Decrement the b_lru_ref count unless the value is already
1684 * zero. If the value is already zero, we need to reclaim the
1685 * buffer, otherwise it gets another trip through the LRU.
1686 */
1687 if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1688 spin_unlock(&bp->b_lock);
1689 return LRU_ROTATE;
1690 }
1691
1692 bp->b_state |= XFS_BSTATE_DISPOSE;
1693 list_lru_isolate_move(lru, item, dispose);
1694 spin_unlock(&bp->b_lock);
1695 return LRU_REMOVED;
1696}
1697
1698static unsigned long
1699xfs_buftarg_shrink_scan(
1700 struct shrinker *shrink,
1701 struct shrink_control *sc)
1702{
1703 struct xfs_buftarg *btp = container_of(shrink,
1704 struct xfs_buftarg, bt_shrinker);
1705 LIST_HEAD(dispose);
1706 unsigned long freed;
1707
1708 freed = list_lru_shrink_walk(&btp->bt_lru, sc,
1709 xfs_buftarg_isolate, &dispose);
1710
1711 while (!list_empty(&dispose)) {
1712 struct xfs_buf *bp;
1713 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1714 list_del_init(&bp->b_lru);
1715 xfs_buf_rele(bp);
1716 }
1717
1718 return freed;
1719}
1720
1721static unsigned long
1722xfs_buftarg_shrink_count(
1723 struct shrinker *shrink,
1724 struct shrink_control *sc)
1725{
1726 struct xfs_buftarg *btp = container_of(shrink,
1727 struct xfs_buftarg, bt_shrinker);
1728 return list_lru_shrink_count(&btp->bt_lru, sc);
1729}
1730
1731void
1732xfs_free_buftarg(
1733 struct xfs_mount *mp,
1734 struct xfs_buftarg *btp)
1735{
1736 unregister_shrinker(&btp->bt_shrinker);
1737 ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
1738 percpu_counter_destroy(&btp->bt_io_count);
1739 list_lru_destroy(&btp->bt_lru);
1740
1741 xfs_blkdev_issue_flush(btp);
1742
1743 kmem_free(btp);
1744}
1745
1746int
1747xfs_setsize_buftarg(
1748 xfs_buftarg_t *btp,
1749 unsigned int sectorsize)
1750{
1751 /* Set up metadata sector size info */
1752 btp->bt_meta_sectorsize = sectorsize;
1753 btp->bt_meta_sectormask = sectorsize - 1;
1754
1755 if (set_blocksize(btp->bt_bdev, sectorsize)) {
1756 xfs_warn(btp->bt_mount,
1757 "Cannot set_blocksize to %u on device %pg",
1758 sectorsize, btp->bt_bdev);
1759 return -EINVAL;
1760 }
1761
1762 /* Set up device logical sector size mask */
1763 btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);
1764 btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;
1765
1766 return 0;
1767}
1768
1769/*
1770 * When allocating the initial buffer target we have not yet
1771 * read in the superblock, so don't know what sized sectors
1772 * are being used at this early stage. Play safe.
1773 */
1774STATIC int
1775xfs_setsize_buftarg_early(
1776 xfs_buftarg_t *btp,
1777 struct block_device *bdev)
1778{
1779 return xfs_setsize_buftarg(btp, bdev_logical_block_size(bdev));
1780}
1781
1782xfs_buftarg_t *
1783xfs_alloc_buftarg(
1784 struct xfs_mount *mp,
1785 struct block_device *bdev)
1786{
1787 xfs_buftarg_t *btp;
1788
1789 btp = kmem_zalloc(sizeof(*btp), KM_SLEEP | KM_NOFS);
1790
1791 btp->bt_mount = mp;
1792 btp->bt_dev = bdev->bd_dev;
1793 btp->bt_bdev = bdev;
1794 btp->bt_bdi = blk_get_backing_dev_info(bdev);
1795
1796 if (xfs_setsize_buftarg_early(btp, bdev))
1797 goto error;
1798
1799 if (list_lru_init(&btp->bt_lru))
1800 goto error;
1801
1802 if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
1803 goto error;
1804
1805 btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
1806 btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
1807 btp->bt_shrinker.seeks = DEFAULT_SEEKS;
1808 btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
1809 register_shrinker(&btp->bt_shrinker);
1810 return btp;
1811
1812error:
1813 kmem_free(btp);
1814 return NULL;
1815}
1816
1817/*
1818 * Add a buffer to the delayed write list.
1819 *
1820 * This queues a buffer for writeout if it hasn't already been. Note that
1821 * neither this routine nor the buffer list submission functions perform
1822 * any internal synchronization. It is expected that the lists are thread-local
1823 * to the callers.
1824 *
1825 * Returns true if we queued up the buffer, or false if it already had
1826 * been on the buffer list.
1827 */
1828bool
1829xfs_buf_delwri_queue(
1830 struct xfs_buf *bp,
1831 struct list_head *list)
1832{
1833 ASSERT(xfs_buf_islocked(bp));
1834 ASSERT(!(bp->b_flags & XBF_READ));
1835
1836 /*
1837 * If the buffer is already marked delwri it already is queued up
1838 * by someone else for imediate writeout. Just ignore it in that
1839 * case.
1840 */
1841 if (bp->b_flags & _XBF_DELWRI_Q) {
1842 trace_xfs_buf_delwri_queued(bp, _RET_IP_);
1843 return false;
1844 }
1845
1846 trace_xfs_buf_delwri_queue(bp, _RET_IP_);
1847
1848 /*
1849 * If a buffer gets written out synchronously or marked stale while it
1850 * is on a delwri list we lazily remove it. To do this, the other party
1851 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1852 * It remains referenced and on the list. In a rare corner case it
1853 * might get readded to a delwri list after the synchronous writeout, in
1854 * which case we need just need to re-add the flag here.
1855 */
1856 bp->b_flags |= _XBF_DELWRI_Q;
1857 if (list_empty(&bp->b_list)) {
1858 atomic_inc(&bp->b_hold);
1859 list_add_tail(&bp->b_list, list);
1860 }
1861
1862 return true;
1863}
1864
1865/*
1866 * Compare function is more complex than it needs to be because
1867 * the return value is only 32 bits and we are doing comparisons
1868 * on 64 bit values
1869 */
1870static int
1871xfs_buf_cmp(
1872 void *priv,
1873 struct list_head *a,
1874 struct list_head *b)
1875{
1876 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
1877 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
1878 xfs_daddr_t diff;
1879
1880 diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
1881 if (diff < 0)
1882 return -1;
1883 if (diff > 0)
1884 return 1;
1885 return 0;
1886}
1887
1888/*
1889 * submit buffers for write.
1890 *
1891 * When we have a large buffer list, we do not want to hold all the buffers
1892 * locked while we block on the request queue waiting for IO dispatch. To avoid
1893 * this problem, we lock and submit buffers in groups of 50, thereby minimising
1894 * the lock hold times for lists which may contain thousands of objects.
1895 *
1896 * To do this, we sort the buffer list before we walk the list to lock and
1897 * submit buffers, and we plug and unplug around each group of buffers we
1898 * submit.
1899 */
1900static int
1901xfs_buf_delwri_submit_buffers(
1902 struct list_head *buffer_list,
1903 struct list_head *wait_list)
1904{
1905 struct xfs_buf *bp, *n;
1906 LIST_HEAD (submit_list);
1907 int pinned = 0;
1908 struct blk_plug plug;
1909
1910 list_sort(NULL, buffer_list, xfs_buf_cmp);
1911
1912 blk_start_plug(&plug);
1913 list_for_each_entry_safe(bp, n, buffer_list, b_list) {
1914 if (!wait_list) {
1915 if (xfs_buf_ispinned(bp)) {
1916 pinned++;
1917 continue;
1918 }
1919 if (!xfs_buf_trylock(bp))
1920 continue;
1921 } else {
1922 xfs_buf_lock(bp);
1923 }
1924
1925 /*
1926 * Someone else might have written the buffer synchronously or
1927 * marked it stale in the meantime. In that case only the
1928 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1929 * reference and remove it from the list here.
1930 */
1931 if (!(bp->b_flags & _XBF_DELWRI_Q)) {
1932 list_del_init(&bp->b_list);
1933 xfs_buf_relse(bp);
1934 continue;
1935 }
1936
1937 trace_xfs_buf_delwri_split(bp, _RET_IP_);
1938
1939 /*
1940 * We do all IO submission async. This means if we need
1941 * to wait for IO completion we need to take an extra
1942 * reference so the buffer is still valid on the other
1943 * side. We need to move the buffer onto the io_list
1944 * at this point so the caller can still access it.
1945 */
1946 bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_WRITE_FAIL);
1947 bp->b_flags |= XBF_WRITE | XBF_ASYNC;
1948 if (wait_list) {
1949 xfs_buf_hold(bp);
1950 list_move_tail(&bp->b_list, wait_list);
1951 } else
1952 list_del_init(&bp->b_list);
1953
1954 xfs_buf_submit(bp);
1955 }
1956 blk_finish_plug(&plug);
1957
1958 return pinned;
1959}
1960
1961/*
1962 * Write out a buffer list asynchronously.
1963 *
1964 * This will take the @buffer_list, write all non-locked and non-pinned buffers
1965 * out and not wait for I/O completion on any of the buffers. This interface
1966 * is only safely useable for callers that can track I/O completion by higher
1967 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
1968 * function.
1969 */
1970int
1971xfs_buf_delwri_submit_nowait(
1972 struct list_head *buffer_list)
1973{
1974 return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
1975}
1976
1977/*
1978 * Write out a buffer list synchronously.
1979 *
1980 * This will take the @buffer_list, write all buffers out and wait for I/O
1981 * completion on all of the buffers. @buffer_list is consumed by the function,
1982 * so callers must have some other way of tracking buffers if they require such
1983 * functionality.
1984 */
1985int
1986xfs_buf_delwri_submit(
1987 struct list_head *buffer_list)
1988{
1989 LIST_HEAD (wait_list);
1990 int error = 0, error2;
1991 struct xfs_buf *bp;
1992
1993 xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);
1994
1995 /* Wait for IO to complete. */
1996 while (!list_empty(&wait_list)) {
1997 bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
1998
1999 list_del_init(&bp->b_list);
2000
2001 /* locking the buffer will wait for async IO completion. */
2002 xfs_buf_lock(bp);
2003 error2 = bp->b_error;
2004 xfs_buf_relse(bp);
2005 if (!error)
2006 error = error2;
2007 }
2008
2009 return error;
2010}
2011
2012int __init
2013xfs_buf_init(void)
2014{
2015 xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
2016 KM_ZONE_HWALIGN, NULL);
2017 if (!xfs_buf_zone)
2018 goto out;
2019
2020 return 0;
2021
2022 out:
2023 return -ENOMEM;
2024}
2025
2026void
2027xfs_buf_terminate(void)
2028{
2029 kmem_zone_destroy(xfs_buf_zone);
2030}
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_log_format.h"
38#include "xfs_trans_resv.h"
39#include "xfs_sb.h"
40#include "xfs_ag.h"
41#include "xfs_mount.h"
42#include "xfs_trace.h"
43#include "xfs_log.h"
44
45static kmem_zone_t *xfs_buf_zone;
46
47static struct workqueue_struct *xfslogd_workqueue;
48
49#ifdef XFS_BUF_LOCK_TRACKING
50# define XB_SET_OWNER(bp) ((bp)->b_last_holder = current->pid)
51# define XB_CLEAR_OWNER(bp) ((bp)->b_last_holder = -1)
52# define XB_GET_OWNER(bp) ((bp)->b_last_holder)
53#else
54# define XB_SET_OWNER(bp) do { } while (0)
55# define XB_CLEAR_OWNER(bp) do { } while (0)
56# define XB_GET_OWNER(bp) do { } while (0)
57#endif
58
59#define xb_to_gfp(flags) \
60 ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : GFP_NOFS) | __GFP_NOWARN)
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) - bp->b_offset;
82}
83
84/*
85 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
86 * b_lru_ref count so that the buffer is freed immediately when the buffer
87 * reference count falls to zero. If the buffer is already on the LRU, we need
88 * to remove the reference that LRU holds on the buffer.
89 *
90 * This prevents build-up of stale buffers on the LRU.
91 */
92void
93xfs_buf_stale(
94 struct xfs_buf *bp)
95{
96 ASSERT(xfs_buf_islocked(bp));
97
98 bp->b_flags |= XBF_STALE;
99
100 /*
101 * Clear the delwri status so that a delwri queue walker will not
102 * flush this buffer to disk now that it is stale. The delwri queue has
103 * a reference to the buffer, so this is safe to do.
104 */
105 bp->b_flags &= ~_XBF_DELWRI_Q;
106
107 spin_lock(&bp->b_lock);
108 atomic_set(&bp->b_lru_ref, 0);
109 if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
110 (list_lru_del(&bp->b_target->bt_lru, &bp->b_lru)))
111 atomic_dec(&bp->b_hold);
112
113 ASSERT(atomic_read(&bp->b_hold) >= 1);
114 spin_unlock(&bp->b_lock);
115}
116
117static int
118xfs_buf_get_maps(
119 struct xfs_buf *bp,
120 int map_count)
121{
122 ASSERT(bp->b_maps == NULL);
123 bp->b_map_count = map_count;
124
125 if (map_count == 1) {
126 bp->b_maps = &bp->__b_map;
127 return 0;
128 }
129
130 bp->b_maps = kmem_zalloc(map_count * sizeof(struct xfs_buf_map),
131 KM_NOFS);
132 if (!bp->b_maps)
133 return ENOMEM;
134 return 0;
135}
136
137/*
138 * Frees b_pages if it was allocated.
139 */
140static void
141xfs_buf_free_maps(
142 struct xfs_buf *bp)
143{
144 if (bp->b_maps != &bp->__b_map) {
145 kmem_free(bp->b_maps);
146 bp->b_maps = NULL;
147 }
148}
149
150struct xfs_buf *
151_xfs_buf_alloc(
152 struct xfs_buftarg *target,
153 struct xfs_buf_map *map,
154 int nmaps,
155 xfs_buf_flags_t flags)
156{
157 struct xfs_buf *bp;
158 int error;
159 int i;
160
161 bp = kmem_zone_zalloc(xfs_buf_zone, KM_NOFS);
162 if (unlikely(!bp))
163 return NULL;
164
165 /*
166 * We don't want certain flags to appear in b_flags unless they are
167 * specifically set by later operations on the buffer.
168 */
169 flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
170
171 atomic_set(&bp->b_hold, 1);
172 atomic_set(&bp->b_lru_ref, 1);
173 init_completion(&bp->b_iowait);
174 INIT_LIST_HEAD(&bp->b_lru);
175 INIT_LIST_HEAD(&bp->b_list);
176 RB_CLEAR_NODE(&bp->b_rbnode);
177 sema_init(&bp->b_sema, 0); /* held, no waiters */
178 spin_lock_init(&bp->b_lock);
179 XB_SET_OWNER(bp);
180 bp->b_target = target;
181 bp->b_flags = flags;
182
183 /*
184 * Set length and io_length to the same value initially.
185 * I/O routines should use io_length, which will be the same in
186 * most cases but may be reset (e.g. XFS recovery).
187 */
188 error = xfs_buf_get_maps(bp, nmaps);
189 if (error) {
190 kmem_zone_free(xfs_buf_zone, bp);
191 return NULL;
192 }
193
194 bp->b_bn = map[0].bm_bn;
195 bp->b_length = 0;
196 for (i = 0; i < nmaps; i++) {
197 bp->b_maps[i].bm_bn = map[i].bm_bn;
198 bp->b_maps[i].bm_len = map[i].bm_len;
199 bp->b_length += map[i].bm_len;
200 }
201 bp->b_io_length = bp->b_length;
202
203 atomic_set(&bp->b_pin_count, 0);
204 init_waitqueue_head(&bp->b_waiters);
205
206 XFS_STATS_INC(xb_create);
207 trace_xfs_buf_init(bp, _RET_IP_);
208
209 return bp;
210}
211
212/*
213 * Allocate a page array capable of holding a specified number
214 * of pages, and point the page buf at it.
215 */
216STATIC int
217_xfs_buf_get_pages(
218 xfs_buf_t *bp,
219 int page_count,
220 xfs_buf_flags_t flags)
221{
222 /* Make sure that we have a page list */
223 if (bp->b_pages == NULL) {
224 bp->b_page_count = page_count;
225 if (page_count <= XB_PAGES) {
226 bp->b_pages = bp->b_page_array;
227 } else {
228 bp->b_pages = kmem_alloc(sizeof(struct page *) *
229 page_count, KM_NOFS);
230 if (bp->b_pages == NULL)
231 return -ENOMEM;
232 }
233 memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
234 }
235 return 0;
236}
237
238/*
239 * Frees b_pages if it was allocated.
240 */
241STATIC void
242_xfs_buf_free_pages(
243 xfs_buf_t *bp)
244{
245 if (bp->b_pages != bp->b_page_array) {
246 kmem_free(bp->b_pages);
247 bp->b_pages = NULL;
248 }
249}
250
251/*
252 * Releases the specified buffer.
253 *
254 * The modification state of any associated pages is left unchanged.
255 * The buffer must not be on any hash - use xfs_buf_rele instead for
256 * hashed and refcounted buffers
257 */
258void
259xfs_buf_free(
260 xfs_buf_t *bp)
261{
262 trace_xfs_buf_free(bp, _RET_IP_);
263
264 ASSERT(list_empty(&bp->b_lru));
265
266 if (bp->b_flags & _XBF_PAGES) {
267 uint i;
268
269 if (xfs_buf_is_vmapped(bp))
270 vm_unmap_ram(bp->b_addr - bp->b_offset,
271 bp->b_page_count);
272
273 for (i = 0; i < bp->b_page_count; i++) {
274 struct page *page = bp->b_pages[i];
275
276 __free_page(page);
277 }
278 } else if (bp->b_flags & _XBF_KMEM)
279 kmem_free(bp->b_addr);
280 _xfs_buf_free_pages(bp);
281 xfs_buf_free_maps(bp);
282 kmem_zone_free(xfs_buf_zone, bp);
283}
284
285/*
286 * Allocates all the pages for buffer in question and builds it's page list.
287 */
288STATIC int
289xfs_buf_allocate_memory(
290 xfs_buf_t *bp,
291 uint flags)
292{
293 size_t size;
294 size_t nbytes, offset;
295 gfp_t gfp_mask = xb_to_gfp(flags);
296 unsigned short page_count, i;
297 xfs_off_t start, end;
298 int error;
299
300 /*
301 * for buffers that are contained within a single page, just allocate
302 * the memory from the heap - there's no need for the complexity of
303 * page arrays to keep allocation down to order 0.
304 */
305 size = BBTOB(bp->b_length);
306 if (size < PAGE_SIZE) {
307 bp->b_addr = kmem_alloc(size, KM_NOFS);
308 if (!bp->b_addr) {
309 /* low memory - use alloc_page loop instead */
310 goto use_alloc_page;
311 }
312
313 if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
314 ((unsigned long)bp->b_addr & PAGE_MASK)) {
315 /* b_addr spans two pages - use alloc_page instead */
316 kmem_free(bp->b_addr);
317 bp->b_addr = NULL;
318 goto use_alloc_page;
319 }
320 bp->b_offset = offset_in_page(bp->b_addr);
321 bp->b_pages = bp->b_page_array;
322 bp->b_pages[0] = virt_to_page(bp->b_addr);
323 bp->b_page_count = 1;
324 bp->b_flags |= _XBF_KMEM;
325 return 0;
326 }
327
328use_alloc_page:
329 start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT;
330 end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1)
331 >> PAGE_SHIFT;
332 page_count = end - start;
333 error = _xfs_buf_get_pages(bp, page_count, flags);
334 if (unlikely(error))
335 return error;
336
337 offset = bp->b_offset;
338 bp->b_flags |= _XBF_PAGES;
339
340 for (i = 0; i < bp->b_page_count; i++) {
341 struct page *page;
342 uint retries = 0;
343retry:
344 page = alloc_page(gfp_mask);
345 if (unlikely(page == NULL)) {
346 if (flags & XBF_READ_AHEAD) {
347 bp->b_page_count = i;
348 error = ENOMEM;
349 goto out_free_pages;
350 }
351
352 /*
353 * This could deadlock.
354 *
355 * But until all the XFS lowlevel code is revamped to
356 * handle buffer allocation failures we can't do much.
357 */
358 if (!(++retries % 100))
359 xfs_err(NULL,
360 "possible memory allocation deadlock in %s (mode:0x%x)",
361 __func__, gfp_mask);
362
363 XFS_STATS_INC(xb_page_retries);
364 congestion_wait(BLK_RW_ASYNC, HZ/50);
365 goto retry;
366 }
367
368 XFS_STATS_INC(xb_page_found);
369
370 nbytes = min_t(size_t, size, PAGE_SIZE - offset);
371 size -= nbytes;
372 bp->b_pages[i] = page;
373 offset = 0;
374 }
375 return 0;
376
377out_free_pages:
378 for (i = 0; i < bp->b_page_count; i++)
379 __free_page(bp->b_pages[i]);
380 return error;
381}
382
383/*
384 * Map buffer into kernel address-space if necessary.
385 */
386STATIC int
387_xfs_buf_map_pages(
388 xfs_buf_t *bp,
389 uint flags)
390{
391 ASSERT(bp->b_flags & _XBF_PAGES);
392 if (bp->b_page_count == 1) {
393 /* A single page buffer is always mappable */
394 bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
395 } else if (flags & XBF_UNMAPPED) {
396 bp->b_addr = NULL;
397 } else {
398 int retried = 0;
399 unsigned noio_flag;
400
401 /*
402 * vm_map_ram() will allocate auxillary structures (e.g.
403 * pagetables) with GFP_KERNEL, yet we are likely to be under
404 * GFP_NOFS context here. Hence we need to tell memory reclaim
405 * that we are in such a context via PF_MEMALLOC_NOIO to prevent
406 * memory reclaim re-entering the filesystem here and
407 * potentially deadlocking.
408 */
409 noio_flag = memalloc_noio_save();
410 do {
411 bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
412 -1, PAGE_KERNEL);
413 if (bp->b_addr)
414 break;
415 vm_unmap_aliases();
416 } while (retried++ <= 1);
417 memalloc_noio_restore(noio_flag);
418
419 if (!bp->b_addr)
420 return -ENOMEM;
421 bp->b_addr += bp->b_offset;
422 }
423
424 return 0;
425}
426
427/*
428 * Finding and Reading Buffers
429 */
430
431/*
432 * Look up, and creates if absent, a lockable buffer for
433 * a given range of an inode. The buffer is returned
434 * locked. No I/O is implied by this call.
435 */
436xfs_buf_t *
437_xfs_buf_find(
438 struct xfs_buftarg *btp,
439 struct xfs_buf_map *map,
440 int nmaps,
441 xfs_buf_flags_t flags,
442 xfs_buf_t *new_bp)
443{
444 size_t numbytes;
445 struct xfs_perag *pag;
446 struct rb_node **rbp;
447 struct rb_node *parent;
448 xfs_buf_t *bp;
449 xfs_daddr_t blkno = map[0].bm_bn;
450 xfs_daddr_t eofs;
451 int numblks = 0;
452 int i;
453
454 for (i = 0; i < nmaps; i++)
455 numblks += map[i].bm_len;
456 numbytes = BBTOB(numblks);
457
458 /* Check for IOs smaller than the sector size / not sector aligned */
459 ASSERT(!(numbytes < btp->bt_meta_sectorsize));
460 ASSERT(!(BBTOB(blkno) & (xfs_off_t)btp->bt_meta_sectormask));
461
462 /*
463 * Corrupted block numbers can get through to here, unfortunately, so we
464 * have to check that the buffer falls within the filesystem bounds.
465 */
466 eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
467 if (blkno >= eofs) {
468 /*
469 * XXX (dgc): we should really be returning EFSCORRUPTED here,
470 * but none of the higher level infrastructure supports
471 * returning a specific error on buffer lookup failures.
472 */
473 xfs_alert(btp->bt_mount,
474 "%s: Block out of range: block 0x%llx, EOFS 0x%llx ",
475 __func__, blkno, eofs);
476 WARN_ON(1);
477 return NULL;
478 }
479
480 /* get tree root */
481 pag = xfs_perag_get(btp->bt_mount,
482 xfs_daddr_to_agno(btp->bt_mount, blkno));
483
484 /* walk tree */
485 spin_lock(&pag->pag_buf_lock);
486 rbp = &pag->pag_buf_tree.rb_node;
487 parent = NULL;
488 bp = NULL;
489 while (*rbp) {
490 parent = *rbp;
491 bp = rb_entry(parent, struct xfs_buf, b_rbnode);
492
493 if (blkno < bp->b_bn)
494 rbp = &(*rbp)->rb_left;
495 else if (blkno > bp->b_bn)
496 rbp = &(*rbp)->rb_right;
497 else {
498 /*
499 * found a block number match. If the range doesn't
500 * match, the only way this is allowed is if the buffer
501 * in the cache is stale and the transaction that made
502 * it stale has not yet committed. i.e. we are
503 * reallocating a busy extent. Skip this buffer and
504 * continue searching to the right for an exact match.
505 */
506 if (bp->b_length != numblks) {
507 ASSERT(bp->b_flags & XBF_STALE);
508 rbp = &(*rbp)->rb_right;
509 continue;
510 }
511 atomic_inc(&bp->b_hold);
512 goto found;
513 }
514 }
515
516 /* No match found */
517 if (new_bp) {
518 rb_link_node(&new_bp->b_rbnode, parent, rbp);
519 rb_insert_color(&new_bp->b_rbnode, &pag->pag_buf_tree);
520 /* the buffer keeps the perag reference until it is freed */
521 new_bp->b_pag = pag;
522 spin_unlock(&pag->pag_buf_lock);
523 } else {
524 XFS_STATS_INC(xb_miss_locked);
525 spin_unlock(&pag->pag_buf_lock);
526 xfs_perag_put(pag);
527 }
528 return new_bp;
529
530found:
531 spin_unlock(&pag->pag_buf_lock);
532 xfs_perag_put(pag);
533
534 if (!xfs_buf_trylock(bp)) {
535 if (flags & XBF_TRYLOCK) {
536 xfs_buf_rele(bp);
537 XFS_STATS_INC(xb_busy_locked);
538 return NULL;
539 }
540 xfs_buf_lock(bp);
541 XFS_STATS_INC(xb_get_locked_waited);
542 }
543
544 /*
545 * if the buffer is stale, clear all the external state associated with
546 * it. We need to keep flags such as how we allocated the buffer memory
547 * intact here.
548 */
549 if (bp->b_flags & XBF_STALE) {
550 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
551 ASSERT(bp->b_iodone == NULL);
552 bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
553 bp->b_ops = NULL;
554 }
555
556 trace_xfs_buf_find(bp, flags, _RET_IP_);
557 XFS_STATS_INC(xb_get_locked);
558 return bp;
559}
560
561/*
562 * Assembles a buffer covering the specified range. The code is optimised for
563 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
564 * more hits than misses.
565 */
566struct xfs_buf *
567xfs_buf_get_map(
568 struct xfs_buftarg *target,
569 struct xfs_buf_map *map,
570 int nmaps,
571 xfs_buf_flags_t flags)
572{
573 struct xfs_buf *bp;
574 struct xfs_buf *new_bp;
575 int error = 0;
576
577 bp = _xfs_buf_find(target, map, nmaps, flags, NULL);
578 if (likely(bp))
579 goto found;
580
581 new_bp = _xfs_buf_alloc(target, map, nmaps, flags);
582 if (unlikely(!new_bp))
583 return NULL;
584
585 error = xfs_buf_allocate_memory(new_bp, flags);
586 if (error) {
587 xfs_buf_free(new_bp);
588 return NULL;
589 }
590
591 bp = _xfs_buf_find(target, map, nmaps, flags, new_bp);
592 if (!bp) {
593 xfs_buf_free(new_bp);
594 return NULL;
595 }
596
597 if (bp != new_bp)
598 xfs_buf_free(new_bp);
599
600found:
601 if (!bp->b_addr) {
602 error = _xfs_buf_map_pages(bp, flags);
603 if (unlikely(error)) {
604 xfs_warn(target->bt_mount,
605 "%s: failed to map pagesn", __func__);
606 xfs_buf_relse(bp);
607 return NULL;
608 }
609 }
610
611 XFS_STATS_INC(xb_get);
612 trace_xfs_buf_get(bp, flags, _RET_IP_);
613 return bp;
614}
615
616STATIC int
617_xfs_buf_read(
618 xfs_buf_t *bp,
619 xfs_buf_flags_t flags)
620{
621 ASSERT(!(flags & XBF_WRITE));
622 ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
623
624 bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD);
625 bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
626
627 xfs_buf_iorequest(bp);
628 if (flags & XBF_ASYNC)
629 return 0;
630 return xfs_buf_iowait(bp);
631}
632
633xfs_buf_t *
634xfs_buf_read_map(
635 struct xfs_buftarg *target,
636 struct xfs_buf_map *map,
637 int nmaps,
638 xfs_buf_flags_t flags,
639 const struct xfs_buf_ops *ops)
640{
641 struct xfs_buf *bp;
642
643 flags |= XBF_READ;
644
645 bp = xfs_buf_get_map(target, map, nmaps, flags);
646 if (bp) {
647 trace_xfs_buf_read(bp, flags, _RET_IP_);
648
649 if (!XFS_BUF_ISDONE(bp)) {
650 XFS_STATS_INC(xb_get_read);
651 bp->b_ops = ops;
652 _xfs_buf_read(bp, flags);
653 } else if (flags & XBF_ASYNC) {
654 /*
655 * Read ahead call which is already satisfied,
656 * drop the buffer
657 */
658 xfs_buf_relse(bp);
659 return NULL;
660 } else {
661 /* We do not want read in the flags */
662 bp->b_flags &= ~XBF_READ;
663 }
664 }
665
666 return bp;
667}
668
669/*
670 * If we are not low on memory then do the readahead in a deadlock
671 * safe manner.
672 */
673void
674xfs_buf_readahead_map(
675 struct xfs_buftarg *target,
676 struct xfs_buf_map *map,
677 int nmaps,
678 const struct xfs_buf_ops *ops)
679{
680 if (bdi_read_congested(target->bt_bdi))
681 return;
682
683 xfs_buf_read_map(target, map, nmaps,
684 XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, ops);
685}
686
687/*
688 * Read an uncached buffer from disk. Allocates and returns a locked
689 * buffer containing the disk contents or nothing.
690 */
691struct xfs_buf *
692xfs_buf_read_uncached(
693 struct xfs_buftarg *target,
694 xfs_daddr_t daddr,
695 size_t numblks,
696 int flags,
697 const struct xfs_buf_ops *ops)
698{
699 struct xfs_buf *bp;
700
701 bp = xfs_buf_get_uncached(target, numblks, flags);
702 if (!bp)
703 return NULL;
704
705 /* set up the buffer for a read IO */
706 ASSERT(bp->b_map_count == 1);
707 bp->b_bn = daddr;
708 bp->b_maps[0].bm_bn = daddr;
709 bp->b_flags |= XBF_READ;
710 bp->b_ops = ops;
711
712 if (XFS_FORCED_SHUTDOWN(target->bt_mount)) {
713 xfs_buf_relse(bp);
714 return NULL;
715 }
716 xfs_buf_iorequest(bp);
717 xfs_buf_iowait(bp);
718 return bp;
719}
720
721/*
722 * Return a buffer allocated as an empty buffer and associated to external
723 * memory via xfs_buf_associate_memory() back to it's empty state.
724 */
725void
726xfs_buf_set_empty(
727 struct xfs_buf *bp,
728 size_t numblks)
729{
730 if (bp->b_pages)
731 _xfs_buf_free_pages(bp);
732
733 bp->b_pages = NULL;
734 bp->b_page_count = 0;
735 bp->b_addr = NULL;
736 bp->b_length = numblks;
737 bp->b_io_length = numblks;
738
739 ASSERT(bp->b_map_count == 1);
740 bp->b_bn = XFS_BUF_DADDR_NULL;
741 bp->b_maps[0].bm_bn = XFS_BUF_DADDR_NULL;
742 bp->b_maps[0].bm_len = bp->b_length;
743}
744
745static inline struct page *
746mem_to_page(
747 void *addr)
748{
749 if ((!is_vmalloc_addr(addr))) {
750 return virt_to_page(addr);
751 } else {
752 return vmalloc_to_page(addr);
753 }
754}
755
756int
757xfs_buf_associate_memory(
758 xfs_buf_t *bp,
759 void *mem,
760 size_t len)
761{
762 int rval;
763 int i = 0;
764 unsigned long pageaddr;
765 unsigned long offset;
766 size_t buflen;
767 int page_count;
768
769 pageaddr = (unsigned long)mem & PAGE_MASK;
770 offset = (unsigned long)mem - pageaddr;
771 buflen = PAGE_ALIGN(len + offset);
772 page_count = buflen >> PAGE_SHIFT;
773
774 /* Free any previous set of page pointers */
775 if (bp->b_pages)
776 _xfs_buf_free_pages(bp);
777
778 bp->b_pages = NULL;
779 bp->b_addr = mem;
780
781 rval = _xfs_buf_get_pages(bp, page_count, 0);
782 if (rval)
783 return rval;
784
785 bp->b_offset = offset;
786
787 for (i = 0; i < bp->b_page_count; i++) {
788 bp->b_pages[i] = mem_to_page((void *)pageaddr);
789 pageaddr += PAGE_SIZE;
790 }
791
792 bp->b_io_length = BTOBB(len);
793 bp->b_length = BTOBB(buflen);
794
795 return 0;
796}
797
798xfs_buf_t *
799xfs_buf_get_uncached(
800 struct xfs_buftarg *target,
801 size_t numblks,
802 int flags)
803{
804 unsigned long page_count;
805 int error, i;
806 struct xfs_buf *bp;
807 DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
808
809 bp = _xfs_buf_alloc(target, &map, 1, 0);
810 if (unlikely(bp == NULL))
811 goto fail;
812
813 page_count = PAGE_ALIGN(numblks << BBSHIFT) >> PAGE_SHIFT;
814 error = _xfs_buf_get_pages(bp, page_count, 0);
815 if (error)
816 goto fail_free_buf;
817
818 for (i = 0; i < page_count; i++) {
819 bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
820 if (!bp->b_pages[i])
821 goto fail_free_mem;
822 }
823 bp->b_flags |= _XBF_PAGES;
824
825 error = _xfs_buf_map_pages(bp, 0);
826 if (unlikely(error)) {
827 xfs_warn(target->bt_mount,
828 "%s: failed to map pages", __func__);
829 goto fail_free_mem;
830 }
831
832 trace_xfs_buf_get_uncached(bp, _RET_IP_);
833 return bp;
834
835 fail_free_mem:
836 while (--i >= 0)
837 __free_page(bp->b_pages[i]);
838 _xfs_buf_free_pages(bp);
839 fail_free_buf:
840 xfs_buf_free_maps(bp);
841 kmem_zone_free(xfs_buf_zone, bp);
842 fail:
843 return NULL;
844}
845
846/*
847 * Increment reference count on buffer, to hold the buffer concurrently
848 * with another thread which may release (free) the buffer asynchronously.
849 * Must hold the buffer already to call this function.
850 */
851void
852xfs_buf_hold(
853 xfs_buf_t *bp)
854{
855 trace_xfs_buf_hold(bp, _RET_IP_);
856 atomic_inc(&bp->b_hold);
857}
858
859/*
860 * Releases a hold on the specified buffer. If the
861 * the hold count is 1, calls xfs_buf_free.
862 */
863void
864xfs_buf_rele(
865 xfs_buf_t *bp)
866{
867 struct xfs_perag *pag = bp->b_pag;
868
869 trace_xfs_buf_rele(bp, _RET_IP_);
870
871 if (!pag) {
872 ASSERT(list_empty(&bp->b_lru));
873 ASSERT(RB_EMPTY_NODE(&bp->b_rbnode));
874 if (atomic_dec_and_test(&bp->b_hold))
875 xfs_buf_free(bp);
876 return;
877 }
878
879 ASSERT(!RB_EMPTY_NODE(&bp->b_rbnode));
880
881 ASSERT(atomic_read(&bp->b_hold) > 0);
882 if (atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock)) {
883 spin_lock(&bp->b_lock);
884 if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
885 /*
886 * If the buffer is added to the LRU take a new
887 * reference to the buffer for the LRU and clear the
888 * (now stale) dispose list state flag
889 */
890 if (list_lru_add(&bp->b_target->bt_lru, &bp->b_lru)) {
891 bp->b_state &= ~XFS_BSTATE_DISPOSE;
892 atomic_inc(&bp->b_hold);
893 }
894 spin_unlock(&bp->b_lock);
895 spin_unlock(&pag->pag_buf_lock);
896 } else {
897 /*
898 * most of the time buffers will already be removed from
899 * the LRU, so optimise that case by checking for the
900 * XFS_BSTATE_DISPOSE flag indicating the last list the
901 * buffer was on was the disposal list
902 */
903 if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
904 list_lru_del(&bp->b_target->bt_lru, &bp->b_lru);
905 } else {
906 ASSERT(list_empty(&bp->b_lru));
907 }
908 spin_unlock(&bp->b_lock);
909
910 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
911 rb_erase(&bp->b_rbnode, &pag->pag_buf_tree);
912 spin_unlock(&pag->pag_buf_lock);
913 xfs_perag_put(pag);
914 xfs_buf_free(bp);
915 }
916 }
917}
918
919
920/*
921 * Lock a buffer object, if it is not already locked.
922 *
923 * If we come across a stale, pinned, locked buffer, we know that we are
924 * being asked to lock a buffer that has been reallocated. Because it is
925 * pinned, we know that the log has not been pushed to disk and hence it
926 * will still be locked. Rather than continuing to have trylock attempts
927 * fail until someone else pushes the log, push it ourselves before
928 * returning. This means that the xfsaild will not get stuck trying
929 * to push on stale inode buffers.
930 */
931int
932xfs_buf_trylock(
933 struct xfs_buf *bp)
934{
935 int locked;
936
937 locked = down_trylock(&bp->b_sema) == 0;
938 if (locked)
939 XB_SET_OWNER(bp);
940
941 trace_xfs_buf_trylock(bp, _RET_IP_);
942 return locked;
943}
944
945/*
946 * Lock a buffer object.
947 *
948 * If we come across a stale, pinned, locked buffer, we know that we
949 * are being asked to lock a buffer that has been reallocated. Because
950 * it is pinned, we know that the log has not been pushed to disk and
951 * hence it will still be locked. Rather than sleeping until someone
952 * else pushes the log, push it ourselves before trying to get the lock.
953 */
954void
955xfs_buf_lock(
956 struct xfs_buf *bp)
957{
958 trace_xfs_buf_lock(bp, _RET_IP_);
959
960 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
961 xfs_log_force(bp->b_target->bt_mount, 0);
962 down(&bp->b_sema);
963 XB_SET_OWNER(bp);
964
965 trace_xfs_buf_lock_done(bp, _RET_IP_);
966}
967
968void
969xfs_buf_unlock(
970 struct xfs_buf *bp)
971{
972 XB_CLEAR_OWNER(bp);
973 up(&bp->b_sema);
974
975 trace_xfs_buf_unlock(bp, _RET_IP_);
976}
977
978STATIC void
979xfs_buf_wait_unpin(
980 xfs_buf_t *bp)
981{
982 DECLARE_WAITQUEUE (wait, current);
983
984 if (atomic_read(&bp->b_pin_count) == 0)
985 return;
986
987 add_wait_queue(&bp->b_waiters, &wait);
988 for (;;) {
989 set_current_state(TASK_UNINTERRUPTIBLE);
990 if (atomic_read(&bp->b_pin_count) == 0)
991 break;
992 io_schedule();
993 }
994 remove_wait_queue(&bp->b_waiters, &wait);
995 set_current_state(TASK_RUNNING);
996}
997
998/*
999 * Buffer Utility Routines
1000 */
1001
1002STATIC void
1003xfs_buf_iodone_work(
1004 struct work_struct *work)
1005{
1006 struct xfs_buf *bp =
1007 container_of(work, xfs_buf_t, b_iodone_work);
1008 bool read = !!(bp->b_flags & XBF_READ);
1009
1010 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
1011
1012 /* only validate buffers that were read without errors */
1013 if (read && bp->b_ops && !bp->b_error && (bp->b_flags & XBF_DONE))
1014 bp->b_ops->verify_read(bp);
1015
1016 if (bp->b_iodone)
1017 (*(bp->b_iodone))(bp);
1018 else if (bp->b_flags & XBF_ASYNC)
1019 xfs_buf_relse(bp);
1020 else {
1021 ASSERT(read && bp->b_ops);
1022 complete(&bp->b_iowait);
1023 }
1024}
1025
1026void
1027xfs_buf_ioend(
1028 struct xfs_buf *bp,
1029 int schedule)
1030{
1031 bool read = !!(bp->b_flags & XBF_READ);
1032
1033 trace_xfs_buf_iodone(bp, _RET_IP_);
1034
1035 if (bp->b_error == 0)
1036 bp->b_flags |= XBF_DONE;
1037
1038 if (bp->b_iodone || (read && bp->b_ops) || (bp->b_flags & XBF_ASYNC)) {
1039 if (schedule) {
1040 INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
1041 queue_work(xfslogd_workqueue, &bp->b_iodone_work);
1042 } else {
1043 xfs_buf_iodone_work(&bp->b_iodone_work);
1044 }
1045 } else {
1046 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
1047 complete(&bp->b_iowait);
1048 }
1049}
1050
1051void
1052xfs_buf_ioerror(
1053 xfs_buf_t *bp,
1054 int error)
1055{
1056 ASSERT(error >= 0 && error <= 0xffff);
1057 bp->b_error = (unsigned short)error;
1058 trace_xfs_buf_ioerror(bp, error, _RET_IP_);
1059}
1060
1061void
1062xfs_buf_ioerror_alert(
1063 struct xfs_buf *bp,
1064 const char *func)
1065{
1066 xfs_alert(bp->b_target->bt_mount,
1067"metadata I/O error: block 0x%llx (\"%s\") error %d numblks %d",
1068 (__uint64_t)XFS_BUF_ADDR(bp), func, bp->b_error, bp->b_length);
1069}
1070
1071/*
1072 * Called when we want to stop a buffer from getting written or read.
1073 * We attach the EIO error, muck with its flags, and call xfs_buf_ioend
1074 * so that the proper iodone callbacks get called.
1075 */
1076STATIC int
1077xfs_bioerror(
1078 xfs_buf_t *bp)
1079{
1080#ifdef XFSERRORDEBUG
1081 ASSERT(XFS_BUF_ISREAD(bp) || bp->b_iodone);
1082#endif
1083
1084 /*
1085 * No need to wait until the buffer is unpinned, we aren't flushing it.
1086 */
1087 xfs_buf_ioerror(bp, EIO);
1088
1089 /*
1090 * We're calling xfs_buf_ioend, so delete XBF_DONE flag.
1091 */
1092 XFS_BUF_UNREAD(bp);
1093 XFS_BUF_UNDONE(bp);
1094 xfs_buf_stale(bp);
1095
1096 xfs_buf_ioend(bp, 0);
1097
1098 return EIO;
1099}
1100
1101/*
1102 * Same as xfs_bioerror, except that we are releasing the buffer
1103 * here ourselves, and avoiding the xfs_buf_ioend call.
1104 * This is meant for userdata errors; metadata bufs come with
1105 * iodone functions attached, so that we can track down errors.
1106 */
1107int
1108xfs_bioerror_relse(
1109 struct xfs_buf *bp)
1110{
1111 int64_t fl = bp->b_flags;
1112 /*
1113 * No need to wait until the buffer is unpinned.
1114 * We aren't flushing it.
1115 *
1116 * chunkhold expects B_DONE to be set, whether
1117 * we actually finish the I/O or not. We don't want to
1118 * change that interface.
1119 */
1120 XFS_BUF_UNREAD(bp);
1121 XFS_BUF_DONE(bp);
1122 xfs_buf_stale(bp);
1123 bp->b_iodone = NULL;
1124 if (!(fl & XBF_ASYNC)) {
1125 /*
1126 * Mark b_error and B_ERROR _both_.
1127 * Lot's of chunkcache code assumes that.
1128 * There's no reason to mark error for
1129 * ASYNC buffers.
1130 */
1131 xfs_buf_ioerror(bp, EIO);
1132 complete(&bp->b_iowait);
1133 } else {
1134 xfs_buf_relse(bp);
1135 }
1136
1137 return EIO;
1138}
1139
1140STATIC int
1141xfs_bdstrat_cb(
1142 struct xfs_buf *bp)
1143{
1144 if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
1145 trace_xfs_bdstrat_shut(bp, _RET_IP_);
1146 /*
1147 * Metadata write that didn't get logged but
1148 * written delayed anyway. These aren't associated
1149 * with a transaction, and can be ignored.
1150 */
1151 if (!bp->b_iodone && !XFS_BUF_ISREAD(bp))
1152 return xfs_bioerror_relse(bp);
1153 else
1154 return xfs_bioerror(bp);
1155 }
1156
1157 xfs_buf_iorequest(bp);
1158 return 0;
1159}
1160
1161int
1162xfs_bwrite(
1163 struct xfs_buf *bp)
1164{
1165 int error;
1166
1167 ASSERT(xfs_buf_islocked(bp));
1168
1169 bp->b_flags |= XBF_WRITE;
1170 bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q | XBF_WRITE_FAIL);
1171
1172 xfs_bdstrat_cb(bp);
1173
1174 error = xfs_buf_iowait(bp);
1175 if (error) {
1176 xfs_force_shutdown(bp->b_target->bt_mount,
1177 SHUTDOWN_META_IO_ERROR);
1178 }
1179 return error;
1180}
1181
1182STATIC void
1183_xfs_buf_ioend(
1184 xfs_buf_t *bp,
1185 int schedule)
1186{
1187 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1188 xfs_buf_ioend(bp, schedule);
1189}
1190
1191STATIC void
1192xfs_buf_bio_end_io(
1193 struct bio *bio,
1194 int error)
1195{
1196 xfs_buf_t *bp = (xfs_buf_t *)bio->bi_private;
1197
1198 /*
1199 * don't overwrite existing errors - otherwise we can lose errors on
1200 * buffers that require multiple bios to complete.
1201 */
1202 if (!bp->b_error)
1203 xfs_buf_ioerror(bp, -error);
1204
1205 if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1206 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1207
1208 _xfs_buf_ioend(bp, 1);
1209 bio_put(bio);
1210}
1211
1212static void
1213xfs_buf_ioapply_map(
1214 struct xfs_buf *bp,
1215 int map,
1216 int *buf_offset,
1217 int *count,
1218 int rw)
1219{
1220 int page_index;
1221 int total_nr_pages = bp->b_page_count;
1222 int nr_pages;
1223 struct bio *bio;
1224 sector_t sector = bp->b_maps[map].bm_bn;
1225 int size;
1226 int offset;
1227
1228 total_nr_pages = bp->b_page_count;
1229
1230 /* skip the pages in the buffer before the start offset */
1231 page_index = 0;
1232 offset = *buf_offset;
1233 while (offset >= PAGE_SIZE) {
1234 page_index++;
1235 offset -= PAGE_SIZE;
1236 }
1237
1238 /*
1239 * Limit the IO size to the length of the current vector, and update the
1240 * remaining IO count for the next time around.
1241 */
1242 size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1243 *count -= size;
1244 *buf_offset += size;
1245
1246next_chunk:
1247 atomic_inc(&bp->b_io_remaining);
1248 nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
1249 if (nr_pages > total_nr_pages)
1250 nr_pages = total_nr_pages;
1251
1252 bio = bio_alloc(GFP_NOIO, nr_pages);
1253 bio->bi_bdev = bp->b_target->bt_bdev;
1254 bio->bi_iter.bi_sector = sector;
1255 bio->bi_end_io = xfs_buf_bio_end_io;
1256 bio->bi_private = bp;
1257
1258
1259 for (; size && nr_pages; nr_pages--, page_index++) {
1260 int rbytes, nbytes = PAGE_SIZE - offset;
1261
1262 if (nbytes > size)
1263 nbytes = size;
1264
1265 rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
1266 offset);
1267 if (rbytes < nbytes)
1268 break;
1269
1270 offset = 0;
1271 sector += BTOBB(nbytes);
1272 size -= nbytes;
1273 total_nr_pages--;
1274 }
1275
1276 if (likely(bio->bi_iter.bi_size)) {
1277 if (xfs_buf_is_vmapped(bp)) {
1278 flush_kernel_vmap_range(bp->b_addr,
1279 xfs_buf_vmap_len(bp));
1280 }
1281 submit_bio(rw, bio);
1282 if (size)
1283 goto next_chunk;
1284 } else {
1285 /*
1286 * This is guaranteed not to be the last io reference count
1287 * because the caller (xfs_buf_iorequest) holds a count itself.
1288 */
1289 atomic_dec(&bp->b_io_remaining);
1290 xfs_buf_ioerror(bp, EIO);
1291 bio_put(bio);
1292 }
1293
1294}
1295
1296STATIC void
1297_xfs_buf_ioapply(
1298 struct xfs_buf *bp)
1299{
1300 struct blk_plug plug;
1301 int rw;
1302 int offset;
1303 int size;
1304 int i;
1305
1306 /*
1307 * Make sure we capture only current IO errors rather than stale errors
1308 * left over from previous use of the buffer (e.g. failed readahead).
1309 */
1310 bp->b_error = 0;
1311
1312 if (bp->b_flags & XBF_WRITE) {
1313 if (bp->b_flags & XBF_SYNCIO)
1314 rw = WRITE_SYNC;
1315 else
1316 rw = WRITE;
1317 if (bp->b_flags & XBF_FUA)
1318 rw |= REQ_FUA;
1319 if (bp->b_flags & XBF_FLUSH)
1320 rw |= REQ_FLUSH;
1321
1322 /*
1323 * Run the write verifier callback function if it exists. If
1324 * this function fails it will mark the buffer with an error and
1325 * the IO should not be dispatched.
1326 */
1327 if (bp->b_ops) {
1328 bp->b_ops->verify_write(bp);
1329 if (bp->b_error) {
1330 xfs_force_shutdown(bp->b_target->bt_mount,
1331 SHUTDOWN_CORRUPT_INCORE);
1332 return;
1333 }
1334 }
1335 } else if (bp->b_flags & XBF_READ_AHEAD) {
1336 rw = READA;
1337 } else {
1338 rw = READ;
1339 }
1340
1341 /* we only use the buffer cache for meta-data */
1342 rw |= REQ_META;
1343
1344 /*
1345 * Walk all the vectors issuing IO on them. Set up the initial offset
1346 * into the buffer and the desired IO size before we start -
1347 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1348 * subsequent call.
1349 */
1350 offset = bp->b_offset;
1351 size = BBTOB(bp->b_io_length);
1352 blk_start_plug(&plug);
1353 for (i = 0; i < bp->b_map_count; i++) {
1354 xfs_buf_ioapply_map(bp, i, &offset, &size, rw);
1355 if (bp->b_error)
1356 break;
1357 if (size <= 0)
1358 break; /* all done */
1359 }
1360 blk_finish_plug(&plug);
1361}
1362
1363void
1364xfs_buf_iorequest(
1365 xfs_buf_t *bp)
1366{
1367 trace_xfs_buf_iorequest(bp, _RET_IP_);
1368
1369 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1370
1371 if (bp->b_flags & XBF_WRITE)
1372 xfs_buf_wait_unpin(bp);
1373 xfs_buf_hold(bp);
1374
1375 /*
1376 * Set the count to 1 initially, this will stop an I/O
1377 * completion callout which happens before we have started
1378 * all the I/O from calling xfs_buf_ioend too early.
1379 */
1380 atomic_set(&bp->b_io_remaining, 1);
1381 _xfs_buf_ioapply(bp);
1382 /*
1383 * If _xfs_buf_ioapply failed, we'll get back here with
1384 * only the reference we took above. _xfs_buf_ioend will
1385 * drop it to zero, so we'd better not queue it for later,
1386 * or we'll free it before it's done.
1387 */
1388 _xfs_buf_ioend(bp, bp->b_error ? 0 : 1);
1389
1390 xfs_buf_rele(bp);
1391}
1392
1393/*
1394 * Waits for I/O to complete on the buffer supplied. It returns immediately if
1395 * no I/O is pending or there is already a pending error on the buffer, in which
1396 * case nothing will ever complete. It returns the I/O error code, if any, or
1397 * 0 if there was no error.
1398 */
1399int
1400xfs_buf_iowait(
1401 xfs_buf_t *bp)
1402{
1403 trace_xfs_buf_iowait(bp, _RET_IP_);
1404
1405 if (!bp->b_error)
1406 wait_for_completion(&bp->b_iowait);
1407
1408 trace_xfs_buf_iowait_done(bp, _RET_IP_);
1409 return bp->b_error;
1410}
1411
1412xfs_caddr_t
1413xfs_buf_offset(
1414 xfs_buf_t *bp,
1415 size_t offset)
1416{
1417 struct page *page;
1418
1419 if (bp->b_addr)
1420 return bp->b_addr + offset;
1421
1422 offset += bp->b_offset;
1423 page = bp->b_pages[offset >> PAGE_SHIFT];
1424 return (xfs_caddr_t)page_address(page) + (offset & (PAGE_SIZE-1));
1425}
1426
1427/*
1428 * Move data into or out of a buffer.
1429 */
1430void
1431xfs_buf_iomove(
1432 xfs_buf_t *bp, /* buffer to process */
1433 size_t boff, /* starting buffer offset */
1434 size_t bsize, /* length to copy */
1435 void *data, /* data address */
1436 xfs_buf_rw_t mode) /* read/write/zero flag */
1437{
1438 size_t bend;
1439
1440 bend = boff + bsize;
1441 while (boff < bend) {
1442 struct page *page;
1443 int page_index, page_offset, csize;
1444
1445 page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1446 page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1447 page = bp->b_pages[page_index];
1448 csize = min_t(size_t, PAGE_SIZE - page_offset,
1449 BBTOB(bp->b_io_length) - boff);
1450
1451 ASSERT((csize + page_offset) <= PAGE_SIZE);
1452
1453 switch (mode) {
1454 case XBRW_ZERO:
1455 memset(page_address(page) + page_offset, 0, csize);
1456 break;
1457 case XBRW_READ:
1458 memcpy(data, page_address(page) + page_offset, csize);
1459 break;
1460 case XBRW_WRITE:
1461 memcpy(page_address(page) + page_offset, data, csize);
1462 }
1463
1464 boff += csize;
1465 data += csize;
1466 }
1467}
1468
1469/*
1470 * Handling of buffer targets (buftargs).
1471 */
1472
1473/*
1474 * Wait for any bufs with callbacks that have been submitted but have not yet
1475 * returned. These buffers will have an elevated hold count, so wait on those
1476 * while freeing all the buffers only held by the LRU.
1477 */
1478static enum lru_status
1479xfs_buftarg_wait_rele(
1480 struct list_head *item,
1481 spinlock_t *lru_lock,
1482 void *arg)
1483
1484{
1485 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1486 struct list_head *dispose = arg;
1487
1488 if (atomic_read(&bp->b_hold) > 1) {
1489 /* need to wait, so skip it this pass */
1490 trace_xfs_buf_wait_buftarg(bp, _RET_IP_);
1491 return LRU_SKIP;
1492 }
1493 if (!spin_trylock(&bp->b_lock))
1494 return LRU_SKIP;
1495
1496 /*
1497 * clear the LRU reference count so the buffer doesn't get
1498 * ignored in xfs_buf_rele().
1499 */
1500 atomic_set(&bp->b_lru_ref, 0);
1501 bp->b_state |= XFS_BSTATE_DISPOSE;
1502 list_move(item, dispose);
1503 spin_unlock(&bp->b_lock);
1504 return LRU_REMOVED;
1505}
1506
1507void
1508xfs_wait_buftarg(
1509 struct xfs_buftarg *btp)
1510{
1511 LIST_HEAD(dispose);
1512 int loop = 0;
1513
1514 /* loop until there is nothing left on the lru list. */
1515 while (list_lru_count(&btp->bt_lru)) {
1516 list_lru_walk(&btp->bt_lru, xfs_buftarg_wait_rele,
1517 &dispose, LONG_MAX);
1518
1519 while (!list_empty(&dispose)) {
1520 struct xfs_buf *bp;
1521 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1522 list_del_init(&bp->b_lru);
1523 if (bp->b_flags & XBF_WRITE_FAIL) {
1524 xfs_alert(btp->bt_mount,
1525"Corruption Alert: Buffer at block 0x%llx had permanent write failures!\n"
1526"Please run xfs_repair to determine the extent of the problem.",
1527 (long long)bp->b_bn);
1528 }
1529 xfs_buf_rele(bp);
1530 }
1531 if (loop++ != 0)
1532 delay(100);
1533 }
1534}
1535
1536static enum lru_status
1537xfs_buftarg_isolate(
1538 struct list_head *item,
1539 spinlock_t *lru_lock,
1540 void *arg)
1541{
1542 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);
1543 struct list_head *dispose = arg;
1544
1545 /*
1546 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1547 * If we fail to get the lock, just skip it.
1548 */
1549 if (!spin_trylock(&bp->b_lock))
1550 return LRU_SKIP;
1551 /*
1552 * Decrement the b_lru_ref count unless the value is already
1553 * zero. If the value is already zero, we need to reclaim the
1554 * buffer, otherwise it gets another trip through the LRU.
1555 */
1556 if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1557 spin_unlock(&bp->b_lock);
1558 return LRU_ROTATE;
1559 }
1560
1561 bp->b_state |= XFS_BSTATE_DISPOSE;
1562 list_move(item, dispose);
1563 spin_unlock(&bp->b_lock);
1564 return LRU_REMOVED;
1565}
1566
1567static unsigned long
1568xfs_buftarg_shrink_scan(
1569 struct shrinker *shrink,
1570 struct shrink_control *sc)
1571{
1572 struct xfs_buftarg *btp = container_of(shrink,
1573 struct xfs_buftarg, bt_shrinker);
1574 LIST_HEAD(dispose);
1575 unsigned long freed;
1576 unsigned long nr_to_scan = sc->nr_to_scan;
1577
1578 freed = list_lru_walk_node(&btp->bt_lru, sc->nid, xfs_buftarg_isolate,
1579 &dispose, &nr_to_scan);
1580
1581 while (!list_empty(&dispose)) {
1582 struct xfs_buf *bp;
1583 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1584 list_del_init(&bp->b_lru);
1585 xfs_buf_rele(bp);
1586 }
1587
1588 return freed;
1589}
1590
1591static unsigned long
1592xfs_buftarg_shrink_count(
1593 struct shrinker *shrink,
1594 struct shrink_control *sc)
1595{
1596 struct xfs_buftarg *btp = container_of(shrink,
1597 struct xfs_buftarg, bt_shrinker);
1598 return list_lru_count_node(&btp->bt_lru, sc->nid);
1599}
1600
1601void
1602xfs_free_buftarg(
1603 struct xfs_mount *mp,
1604 struct xfs_buftarg *btp)
1605{
1606 unregister_shrinker(&btp->bt_shrinker);
1607 list_lru_destroy(&btp->bt_lru);
1608
1609 if (mp->m_flags & XFS_MOUNT_BARRIER)
1610 xfs_blkdev_issue_flush(btp);
1611
1612 kmem_free(btp);
1613}
1614
1615int
1616xfs_setsize_buftarg(
1617 xfs_buftarg_t *btp,
1618 unsigned int blocksize,
1619 unsigned int sectorsize)
1620{
1621 /* Set up metadata sector size info */
1622 btp->bt_meta_sectorsize = sectorsize;
1623 btp->bt_meta_sectormask = sectorsize - 1;
1624
1625 if (set_blocksize(btp->bt_bdev, sectorsize)) {
1626 char name[BDEVNAME_SIZE];
1627
1628 bdevname(btp->bt_bdev, name);
1629
1630 xfs_warn(btp->bt_mount,
1631 "Cannot set_blocksize to %u on device %s",
1632 sectorsize, name);
1633 return EINVAL;
1634 }
1635
1636 /* Set up device logical sector size mask */
1637 btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);
1638 btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;
1639
1640 return 0;
1641}
1642
1643/*
1644 * When allocating the initial buffer target we have not yet
1645 * read in the superblock, so don't know what sized sectors
1646 * are being used at this early stage. Play safe.
1647 */
1648STATIC int
1649xfs_setsize_buftarg_early(
1650 xfs_buftarg_t *btp,
1651 struct block_device *bdev)
1652{
1653 return xfs_setsize_buftarg(btp, PAGE_SIZE,
1654 bdev_logical_block_size(bdev));
1655}
1656
1657xfs_buftarg_t *
1658xfs_alloc_buftarg(
1659 struct xfs_mount *mp,
1660 struct block_device *bdev,
1661 int external,
1662 const char *fsname)
1663{
1664 xfs_buftarg_t *btp;
1665
1666 btp = kmem_zalloc(sizeof(*btp), KM_SLEEP | KM_NOFS);
1667
1668 btp->bt_mount = mp;
1669 btp->bt_dev = bdev->bd_dev;
1670 btp->bt_bdev = bdev;
1671 btp->bt_bdi = blk_get_backing_dev_info(bdev);
1672 if (!btp->bt_bdi)
1673 goto error;
1674
1675 if (xfs_setsize_buftarg_early(btp, bdev))
1676 goto error;
1677
1678 if (list_lru_init(&btp->bt_lru))
1679 goto error;
1680
1681 btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
1682 btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
1683 btp->bt_shrinker.seeks = DEFAULT_SEEKS;
1684 btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
1685 register_shrinker(&btp->bt_shrinker);
1686 return btp;
1687
1688error:
1689 kmem_free(btp);
1690 return NULL;
1691}
1692
1693/*
1694 * Add a buffer to the delayed write list.
1695 *
1696 * This queues a buffer for writeout if it hasn't already been. Note that
1697 * neither this routine nor the buffer list submission functions perform
1698 * any internal synchronization. It is expected that the lists are thread-local
1699 * to the callers.
1700 *
1701 * Returns true if we queued up the buffer, or false if it already had
1702 * been on the buffer list.
1703 */
1704bool
1705xfs_buf_delwri_queue(
1706 struct xfs_buf *bp,
1707 struct list_head *list)
1708{
1709 ASSERT(xfs_buf_islocked(bp));
1710 ASSERT(!(bp->b_flags & XBF_READ));
1711
1712 /*
1713 * If the buffer is already marked delwri it already is queued up
1714 * by someone else for imediate writeout. Just ignore it in that
1715 * case.
1716 */
1717 if (bp->b_flags & _XBF_DELWRI_Q) {
1718 trace_xfs_buf_delwri_queued(bp, _RET_IP_);
1719 return false;
1720 }
1721
1722 trace_xfs_buf_delwri_queue(bp, _RET_IP_);
1723
1724 /*
1725 * If a buffer gets written out synchronously or marked stale while it
1726 * is on a delwri list we lazily remove it. To do this, the other party
1727 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
1728 * It remains referenced and on the list. In a rare corner case it
1729 * might get readded to a delwri list after the synchronous writeout, in
1730 * which case we need just need to re-add the flag here.
1731 */
1732 bp->b_flags |= _XBF_DELWRI_Q;
1733 if (list_empty(&bp->b_list)) {
1734 atomic_inc(&bp->b_hold);
1735 list_add_tail(&bp->b_list, list);
1736 }
1737
1738 return true;
1739}
1740
1741/*
1742 * Compare function is more complex than it needs to be because
1743 * the return value is only 32 bits and we are doing comparisons
1744 * on 64 bit values
1745 */
1746static int
1747xfs_buf_cmp(
1748 void *priv,
1749 struct list_head *a,
1750 struct list_head *b)
1751{
1752 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);
1753 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
1754 xfs_daddr_t diff;
1755
1756 diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
1757 if (diff < 0)
1758 return -1;
1759 if (diff > 0)
1760 return 1;
1761 return 0;
1762}
1763
1764static int
1765__xfs_buf_delwri_submit(
1766 struct list_head *buffer_list,
1767 struct list_head *io_list,
1768 bool wait)
1769{
1770 struct blk_plug plug;
1771 struct xfs_buf *bp, *n;
1772 int pinned = 0;
1773
1774 list_for_each_entry_safe(bp, n, buffer_list, b_list) {
1775 if (!wait) {
1776 if (xfs_buf_ispinned(bp)) {
1777 pinned++;
1778 continue;
1779 }
1780 if (!xfs_buf_trylock(bp))
1781 continue;
1782 } else {
1783 xfs_buf_lock(bp);
1784 }
1785
1786 /*
1787 * Someone else might have written the buffer synchronously or
1788 * marked it stale in the meantime. In that case only the
1789 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
1790 * reference and remove it from the list here.
1791 */
1792 if (!(bp->b_flags & _XBF_DELWRI_Q)) {
1793 list_del_init(&bp->b_list);
1794 xfs_buf_relse(bp);
1795 continue;
1796 }
1797
1798 list_move_tail(&bp->b_list, io_list);
1799 trace_xfs_buf_delwri_split(bp, _RET_IP_);
1800 }
1801
1802 list_sort(NULL, io_list, xfs_buf_cmp);
1803
1804 blk_start_plug(&plug);
1805 list_for_each_entry_safe(bp, n, io_list, b_list) {
1806 bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_ASYNC | XBF_WRITE_FAIL);
1807 bp->b_flags |= XBF_WRITE;
1808
1809 if (!wait) {
1810 bp->b_flags |= XBF_ASYNC;
1811 list_del_init(&bp->b_list);
1812 }
1813 xfs_bdstrat_cb(bp);
1814 }
1815 blk_finish_plug(&plug);
1816
1817 return pinned;
1818}
1819
1820/*
1821 * Write out a buffer list asynchronously.
1822 *
1823 * This will take the @buffer_list, write all non-locked and non-pinned buffers
1824 * out and not wait for I/O completion on any of the buffers. This interface
1825 * is only safely useable for callers that can track I/O completion by higher
1826 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
1827 * function.
1828 */
1829int
1830xfs_buf_delwri_submit_nowait(
1831 struct list_head *buffer_list)
1832{
1833 LIST_HEAD (io_list);
1834 return __xfs_buf_delwri_submit(buffer_list, &io_list, false);
1835}
1836
1837/*
1838 * Write out a buffer list synchronously.
1839 *
1840 * This will take the @buffer_list, write all buffers out and wait for I/O
1841 * completion on all of the buffers. @buffer_list is consumed by the function,
1842 * so callers must have some other way of tracking buffers if they require such
1843 * functionality.
1844 */
1845int
1846xfs_buf_delwri_submit(
1847 struct list_head *buffer_list)
1848{
1849 LIST_HEAD (io_list);
1850 int error = 0, error2;
1851 struct xfs_buf *bp;
1852
1853 __xfs_buf_delwri_submit(buffer_list, &io_list, true);
1854
1855 /* Wait for IO to complete. */
1856 while (!list_empty(&io_list)) {
1857 bp = list_first_entry(&io_list, struct xfs_buf, b_list);
1858
1859 list_del_init(&bp->b_list);
1860 error2 = xfs_buf_iowait(bp);
1861 xfs_buf_relse(bp);
1862 if (!error)
1863 error = error2;
1864 }
1865
1866 return error;
1867}
1868
1869int __init
1870xfs_buf_init(void)
1871{
1872 xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
1873 KM_ZONE_HWALIGN, NULL);
1874 if (!xfs_buf_zone)
1875 goto out;
1876
1877 xfslogd_workqueue = alloc_workqueue("xfslogd",
1878 WQ_MEM_RECLAIM | WQ_HIGHPRI, 1);
1879 if (!xfslogd_workqueue)
1880 goto out_free_buf_zone;
1881
1882 return 0;
1883
1884 out_free_buf_zone:
1885 kmem_zone_destroy(xfs_buf_zone);
1886 out:
1887 return -ENOMEM;
1888}
1889
1890void
1891xfs_buf_terminate(void)
1892{
1893 destroy_workqueue(xfslogd_workqueue);
1894 kmem_zone_destroy(xfs_buf_zone);
1895}