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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.4 * All Rights Reserved.5 */6#include "xfs.h"7#include <linux/backing-dev.h>8#include <linux/dax.h>9 10#include "xfs_shared.h"11#include "xfs_format.h"12#include "xfs_log_format.h"13#include "xfs_trans_resv.h"14#include "xfs_mount.h"15#include "xfs_trace.h"16#include "xfs_log.h"17#include "xfs_log_recover.h"18#include "xfs_log_priv.h"19#include "xfs_trans.h"20#include "xfs_buf_item.h"21#include "xfs_errortag.h"22#include "xfs_error.h"23#include "xfs_ag.h"24#include "xfs_buf_mem.h"25 26struct kmem_cache *xfs_buf_cache;27 28/*29 * Locking orders30 *31 * xfs_buf_ioacct_inc:32 * xfs_buf_ioacct_dec:33 * b_sema (caller holds)34 * b_lock35 *36 * xfs_buf_stale:37 * b_sema (caller holds)38 * b_lock39 * lru_lock40 *41 * xfs_buf_rele:42 * b_lock43 * pag_buf_lock44 * lru_lock45 *46 * xfs_buftarg_drain_rele47 * lru_lock48 * b_lock (trylock due to inversion)49 *50 * xfs_buftarg_isolate51 * lru_lock52 * b_lock (trylock due to inversion)53 */54 55static int __xfs_buf_submit(struct xfs_buf *bp, bool wait);56 57static inline int58xfs_buf_submit(59 struct xfs_buf *bp)60{61 return __xfs_buf_submit(bp, !(bp->b_flags & XBF_ASYNC));62}63 64static inline bool xfs_buf_is_uncached(struct xfs_buf *bp)65{66 return bp->b_rhash_key == XFS_BUF_DADDR_NULL;67}68 69static inline int70xfs_buf_is_vmapped(71 struct xfs_buf *bp)72{73 /*74 * Return true if the buffer is vmapped.75 *76 * b_addr is null if the buffer is not mapped, but the code is clever77 * enough to know it doesn't have to map a single page, so the check has78 * to be both for b_addr and bp->b_page_count > 1.79 */80 return bp->b_addr && bp->b_page_count > 1;81}82 83static inline int84xfs_buf_vmap_len(85 struct xfs_buf *bp)86{87 return (bp->b_page_count * PAGE_SIZE);88}89 90/*91 * Bump the I/O in flight count on the buftarg if we haven't yet done so for92 * this buffer. The count is incremented once per buffer (per hold cycle)93 * because the corresponding decrement is deferred to buffer release. Buffers94 * can undergo I/O multiple times in a hold-release cycle and per buffer I/O95 * tracking adds unnecessary overhead. This is used for sychronization purposes96 * with unmount (see xfs_buftarg_drain()), so all we really need is a count of97 * in-flight buffers.98 *99 * Buffers that are never released (e.g., superblock, iclog buffers) must set100 * the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count101 * never reaches zero and unmount hangs indefinitely.102 */103static inline void104xfs_buf_ioacct_inc(105 struct xfs_buf *bp)106{107 if (bp->b_flags & XBF_NO_IOACCT)108 return;109 110 ASSERT(bp->b_flags & XBF_ASYNC);111 spin_lock(&bp->b_lock);112 if (!(bp->b_state & XFS_BSTATE_IN_FLIGHT)) {113 bp->b_state |= XFS_BSTATE_IN_FLIGHT;114 percpu_counter_inc(&bp->b_target->bt_io_count);115 }116 spin_unlock(&bp->b_lock);117}118 119/*120 * Clear the in-flight state on a buffer about to be released to the LRU or121 * freed and unaccount from the buftarg.122 */123static inline void124__xfs_buf_ioacct_dec(125 struct xfs_buf *bp)126{127 lockdep_assert_held(&bp->b_lock);128 129 if (bp->b_state & XFS_BSTATE_IN_FLIGHT) {130 bp->b_state &= ~XFS_BSTATE_IN_FLIGHT;131 percpu_counter_dec(&bp->b_target->bt_io_count);132 }133}134 135static inline void136xfs_buf_ioacct_dec(137 struct xfs_buf *bp)138{139 spin_lock(&bp->b_lock);140 __xfs_buf_ioacct_dec(bp);141 spin_unlock(&bp->b_lock);142}143 144/*145 * When we mark a buffer stale, we remove the buffer from the LRU and clear the146 * b_lru_ref count so that the buffer is freed immediately when the buffer147 * reference count falls to zero. If the buffer is already on the LRU, we need148 * to remove the reference that LRU holds on the buffer.149 *150 * This prevents build-up of stale buffers on the LRU.151 */152void153xfs_buf_stale(154 struct xfs_buf *bp)155{156 ASSERT(xfs_buf_islocked(bp));157 158 bp->b_flags |= XBF_STALE;159 160 /*161 * Clear the delwri status so that a delwri queue walker will not162 * flush this buffer to disk now that it is stale. The delwri queue has163 * a reference to the buffer, so this is safe to do.164 */165 bp->b_flags &= ~_XBF_DELWRI_Q;166 167 /*168 * Once the buffer is marked stale and unlocked, a subsequent lookup169 * could reset b_flags. There is no guarantee that the buffer is170 * unaccounted (released to LRU) before that occurs. Drop in-flight171 * status now to preserve accounting consistency.172 */173 spin_lock(&bp->b_lock);174 __xfs_buf_ioacct_dec(bp);175 176 atomic_set(&bp->b_lru_ref, 0);177 if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&178 (list_lru_del_obj(&bp->b_target->bt_lru, &bp->b_lru)))179 atomic_dec(&bp->b_hold);180 181 ASSERT(atomic_read(&bp->b_hold) >= 1);182 spin_unlock(&bp->b_lock);183}184 185static int186xfs_buf_get_maps(187 struct xfs_buf *bp,188 int map_count)189{190 ASSERT(bp->b_maps == NULL);191 bp->b_map_count = map_count;192 193 if (map_count == 1) {194 bp->b_maps = &bp->__b_map;195 return 0;196 }197 198 bp->b_maps = kzalloc(map_count * sizeof(struct xfs_buf_map),199 GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);200 if (!bp->b_maps)201 return -ENOMEM;202 return 0;203}204 205/*206 * Frees b_pages if it was allocated.207 */208static void209xfs_buf_free_maps(210 struct xfs_buf *bp)211{212 if (bp->b_maps != &bp->__b_map) {213 kfree(bp->b_maps);214 bp->b_maps = NULL;215 }216}217 218static int219_xfs_buf_alloc(220 struct xfs_buftarg *target,221 struct xfs_buf_map *map,222 int nmaps,223 xfs_buf_flags_t flags,224 struct xfs_buf **bpp)225{226 struct xfs_buf *bp;227 int error;228 int i;229 230 *bpp = NULL;231 bp = kmem_cache_zalloc(xfs_buf_cache,232 GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);233 234 /*235 * We don't want certain flags to appear in b_flags unless they are236 * specifically set by later operations on the buffer.237 */238 flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);239 240 atomic_set(&bp->b_hold, 1);241 atomic_set(&bp->b_lru_ref, 1);242 init_completion(&bp->b_iowait);243 INIT_LIST_HEAD(&bp->b_lru);244 INIT_LIST_HEAD(&bp->b_list);245 INIT_LIST_HEAD(&bp->b_li_list);246 sema_init(&bp->b_sema, 0); /* held, no waiters */247 spin_lock_init(&bp->b_lock);248 bp->b_target = target;249 bp->b_mount = target->bt_mount;250 bp->b_flags = flags;251 252 /*253 * Set length and io_length to the same value initially.254 * I/O routines should use io_length, which will be the same in255 * most cases but may be reset (e.g. XFS recovery).256 */257 error = xfs_buf_get_maps(bp, nmaps);258 if (error) {259 kmem_cache_free(xfs_buf_cache, bp);260 return error;261 }262 263 bp->b_rhash_key = map[0].bm_bn;264 bp->b_length = 0;265 for (i = 0; i < nmaps; i++) {266 bp->b_maps[i].bm_bn = map[i].bm_bn;267 bp->b_maps[i].bm_len = map[i].bm_len;268 bp->b_length += map[i].bm_len;269 }270 271 atomic_set(&bp->b_pin_count, 0);272 init_waitqueue_head(&bp->b_waiters);273 274 XFS_STATS_INC(bp->b_mount, xb_create);275 trace_xfs_buf_init(bp, _RET_IP_);276 277 *bpp = bp;278 return 0;279}280 281static void282xfs_buf_free_pages(283 struct xfs_buf *bp)284{285 uint i;286 287 ASSERT(bp->b_flags & _XBF_PAGES);288 289 if (xfs_buf_is_vmapped(bp))290 vm_unmap_ram(bp->b_addr, bp->b_page_count);291 292 for (i = 0; i < bp->b_page_count; i++) {293 if (bp->b_pages[i])294 __free_page(bp->b_pages[i]);295 }296 mm_account_reclaimed_pages(bp->b_page_count);297 298 if (bp->b_pages != bp->b_page_array)299 kfree(bp->b_pages);300 bp->b_pages = NULL;301 bp->b_flags &= ~_XBF_PAGES;302}303 304static void305xfs_buf_free_callback(306 struct callback_head *cb)307{308 struct xfs_buf *bp = container_of(cb, struct xfs_buf, b_rcu);309 310 xfs_buf_free_maps(bp);311 kmem_cache_free(xfs_buf_cache, bp);312}313 314static void315xfs_buf_free(316 struct xfs_buf *bp)317{318 trace_xfs_buf_free(bp, _RET_IP_);319 320 ASSERT(list_empty(&bp->b_lru));321 322 if (xfs_buftarg_is_mem(bp->b_target))323 xmbuf_unmap_page(bp);324 else if (bp->b_flags & _XBF_PAGES)325 xfs_buf_free_pages(bp);326 else if (bp->b_flags & _XBF_KMEM)327 kfree(bp->b_addr);328 329 call_rcu(&bp->b_rcu, xfs_buf_free_callback);330}331 332static int333xfs_buf_alloc_kmem(334 struct xfs_buf *bp,335 xfs_buf_flags_t flags)336{337 gfp_t gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL;338 size_t size = BBTOB(bp->b_length);339 340 /* Assure zeroed buffer for non-read cases. */341 if (!(flags & XBF_READ))342 gfp_mask |= __GFP_ZERO;343 344 bp->b_addr = kmalloc(size, gfp_mask);345 if (!bp->b_addr)346 return -ENOMEM;347 348 if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=349 ((unsigned long)bp->b_addr & PAGE_MASK)) {350 /* b_addr spans two pages - use alloc_page instead */351 kfree(bp->b_addr);352 bp->b_addr = NULL;353 return -ENOMEM;354 }355 bp->b_offset = offset_in_page(bp->b_addr);356 bp->b_pages = bp->b_page_array;357 bp->b_pages[0] = kmem_to_page(bp->b_addr);358 bp->b_page_count = 1;359 bp->b_flags |= _XBF_KMEM;360 return 0;361}362 363static int364xfs_buf_alloc_pages(365 struct xfs_buf *bp,366 xfs_buf_flags_t flags)367{368 gfp_t gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOWARN;369 long filled = 0;370 371 if (flags & XBF_READ_AHEAD)372 gfp_mask |= __GFP_NORETRY;373 374 /* Make sure that we have a page list */375 bp->b_page_count = DIV_ROUND_UP(BBTOB(bp->b_length), PAGE_SIZE);376 if (bp->b_page_count <= XB_PAGES) {377 bp->b_pages = bp->b_page_array;378 } else {379 bp->b_pages = kzalloc(sizeof(struct page *) * bp->b_page_count,380 gfp_mask);381 if (!bp->b_pages)382 return -ENOMEM;383 }384 bp->b_flags |= _XBF_PAGES;385 386 /* Assure zeroed buffer for non-read cases. */387 if (!(flags & XBF_READ))388 gfp_mask |= __GFP_ZERO;389 390 /*391 * Bulk filling of pages can take multiple calls. Not filling the entire392 * array is not an allocation failure, so don't back off if we get at393 * least one extra page.394 */395 for (;;) {396 long last = filled;397 398 filled = alloc_pages_bulk_array(gfp_mask, bp->b_page_count,399 bp->b_pages);400 if (filled == bp->b_page_count) {401 XFS_STATS_INC(bp->b_mount, xb_page_found);402 break;403 }404 405 if (filled != last)406 continue;407 408 if (flags & XBF_READ_AHEAD) {409 xfs_buf_free_pages(bp);410 return -ENOMEM;411 }412 413 XFS_STATS_INC(bp->b_mount, xb_page_retries);414 memalloc_retry_wait(gfp_mask);415 }416 return 0;417}418 419/*420 * Map buffer into kernel address-space if necessary.421 */422STATIC int423_xfs_buf_map_pages(424 struct xfs_buf *bp,425 xfs_buf_flags_t flags)426{427 ASSERT(bp->b_flags & _XBF_PAGES);428 if (bp->b_page_count == 1) {429 /* A single page buffer is always mappable */430 bp->b_addr = page_address(bp->b_pages[0]);431 } else if (flags & XBF_UNMAPPED) {432 bp->b_addr = NULL;433 } else {434 int retried = 0;435 unsigned nofs_flag;436 437 /*438 * vm_map_ram() will allocate auxiliary structures (e.g.439 * pagetables) with GFP_KERNEL, yet we often under a scoped nofs440 * context here. Mixing GFP_KERNEL with GFP_NOFS allocations441 * from the same call site that can be run from both above and442 * below memory reclaim causes lockdep false positives. Hence we443 * always need to force this allocation to nofs context because444 * we can't pass __GFP_NOLOCKDEP down to auxillary structures to445 * prevent false positive lockdep reports.446 *447 * XXX(dgc): I think dquot reclaim is the only place we can get448 * to this function from memory reclaim context now. If we fix449 * that like we've fixed inode reclaim to avoid writeback from450 * reclaim, this nofs wrapping can go away.451 */452 nofs_flag = memalloc_nofs_save();453 do {454 bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,455 -1);456 if (bp->b_addr)457 break;458 vm_unmap_aliases();459 } while (retried++ <= 1);460 memalloc_nofs_restore(nofs_flag);461 462 if (!bp->b_addr)463 return -ENOMEM;464 }465 466 return 0;467}468 469/*470 * Finding and Reading Buffers471 */472static int473_xfs_buf_obj_cmp(474 struct rhashtable_compare_arg *arg,475 const void *obj)476{477 const struct xfs_buf_map *map = arg->key;478 const struct xfs_buf *bp = obj;479 480 /*481 * The key hashing in the lookup path depends on the key being the482 * first element of the compare_arg, make sure to assert this.483 */484 BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);485 486 if (bp->b_rhash_key != map->bm_bn)487 return 1;488 489 if (unlikely(bp->b_length != map->bm_len)) {490 /*491 * found a block number match. If the range doesn't492 * match, the only way this is allowed is if the buffer493 * in the cache is stale and the transaction that made494 * it stale has not yet committed. i.e. we are495 * reallocating a busy extent. Skip this buffer and496 * continue searching for an exact match.497 *498 * Note: If we're scanning for incore buffers to stale, don't499 * complain if we find non-stale buffers.500 */501 if (!(map->bm_flags & XBM_LIVESCAN))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_rhash_key),513 .head_offset = offsetof(struct xfs_buf, b_rhash_head),514 .automatic_shrinking = true,515 .obj_cmpfn = _xfs_buf_obj_cmp,516};517 518int519xfs_buf_cache_init(520 struct xfs_buf_cache *bch)521{522 spin_lock_init(&bch->bc_lock);523 return rhashtable_init(&bch->bc_hash, &xfs_buf_hash_params);524}525 526void527xfs_buf_cache_destroy(528 struct xfs_buf_cache *bch)529{530 rhashtable_destroy(&bch->bc_hash);531}532 533static int534xfs_buf_map_verify(535 struct xfs_buftarg *btp,536 struct xfs_buf_map *map)537{538 xfs_daddr_t eofs;539 540 /* Check for IOs smaller than the sector size / not sector aligned */541 ASSERT(!(BBTOB(map->bm_len) < btp->bt_meta_sectorsize));542 ASSERT(!(BBTOB(map->bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));543 544 /*545 * Corrupted block numbers can get through to here, unfortunately, so we546 * have to check that the buffer falls within the filesystem bounds.547 */548 eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);549 if (map->bm_bn < 0 || map->bm_bn >= eofs) {550 xfs_alert(btp->bt_mount,551 "%s: daddr 0x%llx out of range, EOFS 0x%llx",552 __func__, map->bm_bn, eofs);553 WARN_ON(1);554 return -EFSCORRUPTED;555 }556 return 0;557}558 559static int560xfs_buf_find_lock(561 struct xfs_buf *bp,562 xfs_buf_flags_t flags)563{564 if (flags & XBF_TRYLOCK) {565 if (!xfs_buf_trylock(bp)) {566 XFS_STATS_INC(bp->b_mount, xb_busy_locked);567 return -EAGAIN;568 }569 } else {570 xfs_buf_lock(bp);571 XFS_STATS_INC(bp->b_mount, xb_get_locked_waited);572 }573 574 /*575 * if the buffer is stale, clear all the external state associated with576 * it. We need to keep flags such as how we allocated the buffer memory577 * intact here.578 */579 if (bp->b_flags & XBF_STALE) {580 if (flags & XBF_LIVESCAN) {581 xfs_buf_unlock(bp);582 return -ENOENT;583 }584 ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);585 bp->b_flags &= _XBF_KMEM | _XBF_PAGES;586 bp->b_ops = NULL;587 }588 return 0;589}590 591static inline int592xfs_buf_lookup(593 struct xfs_buf_cache *bch,594 struct xfs_buf_map *map,595 xfs_buf_flags_t flags,596 struct xfs_buf **bpp)597{598 struct xfs_buf *bp;599 int error;600 601 rcu_read_lock();602 bp = rhashtable_lookup(&bch->bc_hash, map, xfs_buf_hash_params);603 if (!bp || !atomic_inc_not_zero(&bp->b_hold)) {604 rcu_read_unlock();605 return -ENOENT;606 }607 rcu_read_unlock();608 609 error = xfs_buf_find_lock(bp, flags);610 if (error) {611 xfs_buf_rele(bp);612 return error;613 }614 615 trace_xfs_buf_find(bp, flags, _RET_IP_);616 *bpp = bp;617 return 0;618}619 620/*621 * Insert the new_bp into the hash table. This consumes the perag reference622 * taken for the lookup regardless of the result of the insert.623 */624static int625xfs_buf_find_insert(626 struct xfs_buftarg *btp,627 struct xfs_buf_cache *bch,628 struct xfs_perag *pag,629 struct xfs_buf_map *cmap,630 struct xfs_buf_map *map,631 int nmaps,632 xfs_buf_flags_t flags,633 struct xfs_buf **bpp)634{635 struct xfs_buf *new_bp;636 struct xfs_buf *bp;637 int error;638 639 error = _xfs_buf_alloc(btp, map, nmaps, flags, &new_bp);640 if (error)641 goto out_drop_pag;642 643 if (xfs_buftarg_is_mem(new_bp->b_target)) {644 error = xmbuf_map_page(new_bp);645 } else if (BBTOB(new_bp->b_length) >= PAGE_SIZE ||646 xfs_buf_alloc_kmem(new_bp, flags) < 0) {647 /*648 * For buffers that fit entirely within a single page, first649 * attempt to allocate the memory from the heap to minimise650 * memory usage. If we can't get heap memory for these small651 * buffers, we fall back to using the page allocator.652 */653 error = xfs_buf_alloc_pages(new_bp, flags);654 }655 if (error)656 goto out_free_buf;657 658 spin_lock(&bch->bc_lock);659 bp = rhashtable_lookup_get_insert_fast(&bch->bc_hash,660 &new_bp->b_rhash_head, xfs_buf_hash_params);661 if (IS_ERR(bp)) {662 error = PTR_ERR(bp);663 spin_unlock(&bch->bc_lock);664 goto out_free_buf;665 }666 if (bp) {667 /* found an existing buffer */668 atomic_inc(&bp->b_hold);669 spin_unlock(&bch->bc_lock);670 error = xfs_buf_find_lock(bp, flags);671 if (error)672 xfs_buf_rele(bp);673 else674 *bpp = bp;675 goto out_free_buf;676 }677 678 /* The new buffer keeps the perag reference until it is freed. */679 new_bp->b_pag = pag;680 spin_unlock(&bch->bc_lock);681 *bpp = new_bp;682 return 0;683 684out_free_buf:685 xfs_buf_free(new_bp);686out_drop_pag:687 if (pag)688 xfs_perag_put(pag);689 return error;690}691 692static inline struct xfs_perag *693xfs_buftarg_get_pag(694 struct xfs_buftarg *btp,695 const struct xfs_buf_map *map)696{697 struct xfs_mount *mp = btp->bt_mount;698 699 if (xfs_buftarg_is_mem(btp))700 return NULL;701 return xfs_perag_get(mp, xfs_daddr_to_agno(mp, map->bm_bn));702}703 704static inline struct xfs_buf_cache *705xfs_buftarg_buf_cache(706 struct xfs_buftarg *btp,707 struct xfs_perag *pag)708{709 if (pag)710 return &pag->pag_bcache;711 return btp->bt_cache;712}713 714/*715 * Assembles a buffer covering the specified range. The code is optimised for716 * cache hits, as metadata intensive workloads will see 3 orders of magnitude717 * more hits than misses.718 */719int720xfs_buf_get_map(721 struct xfs_buftarg *btp,722 struct xfs_buf_map *map,723 int nmaps,724 xfs_buf_flags_t flags,725 struct xfs_buf **bpp)726{727 struct xfs_buf_cache *bch;728 struct xfs_perag *pag;729 struct xfs_buf *bp = NULL;730 struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn };731 int error;732 int i;733 734 if (flags & XBF_LIVESCAN)735 cmap.bm_flags |= XBM_LIVESCAN;736 for (i = 0; i < nmaps; i++)737 cmap.bm_len += map[i].bm_len;738 739 error = xfs_buf_map_verify(btp, &cmap);740 if (error)741 return error;742 743 pag = xfs_buftarg_get_pag(btp, &cmap);744 bch = xfs_buftarg_buf_cache(btp, pag);745 746 error = xfs_buf_lookup(bch, &cmap, flags, &bp);747 if (error && error != -ENOENT)748 goto out_put_perag;749 750 /* cache hits always outnumber misses by at least 10:1 */751 if (unlikely(!bp)) {752 XFS_STATS_INC(btp->bt_mount, xb_miss_locked);753 754 if (flags & XBF_INCORE)755 goto out_put_perag;756 757 /* xfs_buf_find_insert() consumes the perag reference. */758 error = xfs_buf_find_insert(btp, bch, pag, &cmap, map, nmaps,759 flags, &bp);760 if (error)761 return error;762 } else {763 XFS_STATS_INC(btp->bt_mount, xb_get_locked);764 if (pag)765 xfs_perag_put(pag);766 }767 768 /* We do not hold a perag reference anymore. */769 if (!bp->b_addr) {770 error = _xfs_buf_map_pages(bp, flags);771 if (unlikely(error)) {772 xfs_warn_ratelimited(btp->bt_mount,773 "%s: failed to map %u pages", __func__,774 bp->b_page_count);775 xfs_buf_relse(bp);776 return error;777 }778 }779 780 /*781 * Clear b_error if this is a lookup from a caller that doesn't expect782 * valid data to be found in the buffer.783 */784 if (!(flags & XBF_READ))785 xfs_buf_ioerror(bp, 0);786 787 XFS_STATS_INC(btp->bt_mount, xb_get);788 trace_xfs_buf_get(bp, flags, _RET_IP_);789 *bpp = bp;790 return 0;791 792out_put_perag:793 if (pag)794 xfs_perag_put(pag);795 return error;796}797 798int799_xfs_buf_read(800 struct xfs_buf *bp,801 xfs_buf_flags_t flags)802{803 ASSERT(!(flags & XBF_WRITE));804 ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);805 806 bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD | XBF_DONE);807 bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);808 809 return xfs_buf_submit(bp);810}811 812/*813 * Reverify a buffer found in cache without an attached ->b_ops.814 *815 * If the caller passed an ops structure and the buffer doesn't have ops816 * assigned, set the ops and use it to verify the contents. If verification817 * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is818 * already in XBF_DONE state on entry.819 *820 * Under normal operations, every in-core buffer is verified on read I/O821 * completion. There are two scenarios that can lead to in-core buffers without822 * an assigned ->b_ops. The first is during log recovery of buffers on a V4823 * filesystem, though these buffers are purged at the end of recovery. The824 * other is online repair, which intentionally reads with a NULL buffer ops to825 * run several verifiers across an in-core buffer in order to establish buffer826 * type. If repair can't establish that, the buffer will be left in memory827 * with NULL buffer ops.828 */829int830xfs_buf_reverify(831 struct xfs_buf *bp,832 const struct xfs_buf_ops *ops)833{834 ASSERT(bp->b_flags & XBF_DONE);835 ASSERT(bp->b_error == 0);836 837 if (!ops || bp->b_ops)838 return 0;839 840 bp->b_ops = ops;841 bp->b_ops->verify_read(bp);842 if (bp->b_error)843 bp->b_flags &= ~XBF_DONE;844 return bp->b_error;845}846 847int848xfs_buf_read_map(849 struct xfs_buftarg *target,850 struct xfs_buf_map *map,851 int nmaps,852 xfs_buf_flags_t flags,853 struct xfs_buf **bpp,854 const struct xfs_buf_ops *ops,855 xfs_failaddr_t fa)856{857 struct xfs_buf *bp;858 int error;859 860 flags |= XBF_READ;861 *bpp = NULL;862 863 error = xfs_buf_get_map(target, map, nmaps, flags, &bp);864 if (error)865 return error;866 867 trace_xfs_buf_read(bp, flags, _RET_IP_);868 869 if (!(bp->b_flags & XBF_DONE)) {870 /* Initiate the buffer read and wait. */871 XFS_STATS_INC(target->bt_mount, xb_get_read);872 bp->b_ops = ops;873 error = _xfs_buf_read(bp, flags);874 875 /* Readahead iodone already dropped the buffer, so exit. */876 if (flags & XBF_ASYNC)877 return 0;878 } else {879 /* Buffer already read; all we need to do is check it. */880 error = xfs_buf_reverify(bp, ops);881 882 /* Readahead already finished; drop the buffer and exit. */883 if (flags & XBF_ASYNC) {884 xfs_buf_relse(bp);885 return 0;886 }887 888 /* We do not want read in the flags */889 bp->b_flags &= ~XBF_READ;890 ASSERT(bp->b_ops != NULL || ops == NULL);891 }892 893 /*894 * If we've had a read error, then the contents of the buffer are895 * invalid and should not be used. To ensure that a followup read tries896 * to pull the buffer from disk again, we clear the XBF_DONE flag and897 * mark the buffer stale. This ensures that anyone who has a current898 * reference to the buffer will interpret it's contents correctly and899 * future cache lookups will also treat it as an empty, uninitialised900 * buffer.901 */902 if (error) {903 /*904 * Check against log shutdown for error reporting because905 * metadata writeback may require a read first and we need to906 * report errors in metadata writeback until the log is shut907 * down. High level transaction read functions already check908 * against mount shutdown, anyway, so we only need to be909 * concerned about low level IO interactions here.910 */911 if (!xlog_is_shutdown(target->bt_mount->m_log))912 xfs_buf_ioerror_alert(bp, fa);913 914 bp->b_flags &= ~XBF_DONE;915 xfs_buf_stale(bp);916 xfs_buf_relse(bp);917 918 /* bad CRC means corrupted metadata */919 if (error == -EFSBADCRC)920 error = -EFSCORRUPTED;921 return error;922 }923 924 *bpp = bp;925 return 0;926}927 928/*929 * If we are not low on memory then do the readahead in a deadlock930 * safe manner.931 */932void933xfs_buf_readahead_map(934 struct xfs_buftarg *target,935 struct xfs_buf_map *map,936 int nmaps,937 const struct xfs_buf_ops *ops)938{939 struct xfs_buf *bp;940 941 /*942 * Currently we don't have a good means or justification for performing943 * xmbuf_map_page asynchronously, so we don't do readahead.944 */945 if (xfs_buftarg_is_mem(target))946 return;947 948 xfs_buf_read_map(target, map, nmaps,949 XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops,950 __this_address);951}952 953/*954 * Read an uncached buffer from disk. Allocates and returns a locked955 * buffer containing the disk contents or nothing. Uncached buffers always have956 * a cache index of XFS_BUF_DADDR_NULL so we can easily determine if the buffer957 * is cached or uncached during fault diagnosis.958 */959int960xfs_buf_read_uncached(961 struct xfs_buftarg *target,962 xfs_daddr_t daddr,963 size_t numblks,964 xfs_buf_flags_t flags,965 struct xfs_buf **bpp,966 const struct xfs_buf_ops *ops)967{968 struct xfs_buf *bp;969 int error;970 971 *bpp = NULL;972 973 error = xfs_buf_get_uncached(target, numblks, flags, &bp);974 if (error)975 return error;976 977 /* set up the buffer for a read IO */978 ASSERT(bp->b_map_count == 1);979 bp->b_rhash_key = XFS_BUF_DADDR_NULL;980 bp->b_maps[0].bm_bn = daddr;981 bp->b_flags |= XBF_READ;982 bp->b_ops = ops;983 984 xfs_buf_submit(bp);985 if (bp->b_error) {986 error = bp->b_error;987 xfs_buf_relse(bp);988 return error;989 }990 991 *bpp = bp;992 return 0;993}994 995int996xfs_buf_get_uncached(997 struct xfs_buftarg *target,998 size_t numblks,999 xfs_buf_flags_t flags,1000 struct xfs_buf **bpp)1001{1002 int error;1003 struct xfs_buf *bp;1004 DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);1005 1006 *bpp = NULL;1007 1008 /* flags might contain irrelevant bits, pass only what we care about */1009 error = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT, &bp);1010 if (error)1011 return error;1012 1013 if (xfs_buftarg_is_mem(bp->b_target))1014 error = xmbuf_map_page(bp);1015 else1016 error = xfs_buf_alloc_pages(bp, flags);1017 if (error)1018 goto fail_free_buf;1019 1020 error = _xfs_buf_map_pages(bp, 0);1021 if (unlikely(error)) {1022 xfs_warn(target->bt_mount,1023 "%s: failed to map pages", __func__);1024 goto fail_free_buf;1025 }1026 1027 trace_xfs_buf_get_uncached(bp, _RET_IP_);1028 *bpp = bp;1029 return 0;1030 1031fail_free_buf:1032 xfs_buf_free(bp);1033 return error;1034}1035 1036/*1037 * Increment reference count on buffer, to hold the buffer concurrently1038 * with another thread which may release (free) the buffer asynchronously.1039 * Must hold the buffer already to call this function.1040 */1041void1042xfs_buf_hold(1043 struct xfs_buf *bp)1044{1045 trace_xfs_buf_hold(bp, _RET_IP_);1046 atomic_inc(&bp->b_hold);1047}1048 1049static void1050xfs_buf_rele_uncached(1051 struct xfs_buf *bp)1052{1053 ASSERT(list_empty(&bp->b_lru));1054 if (atomic_dec_and_test(&bp->b_hold)) {1055 xfs_buf_ioacct_dec(bp);1056 xfs_buf_free(bp);1057 }1058}1059 1060static void1061xfs_buf_rele_cached(1062 struct xfs_buf *bp)1063{1064 struct xfs_buftarg *btp = bp->b_target;1065 struct xfs_perag *pag = bp->b_pag;1066 struct xfs_buf_cache *bch = xfs_buftarg_buf_cache(btp, pag);1067 bool release;1068 bool freebuf = false;1069 1070 trace_xfs_buf_rele(bp, _RET_IP_);1071 1072 ASSERT(atomic_read(&bp->b_hold) > 0);1073 1074 /*1075 * We grab the b_lock here first to serialise racing xfs_buf_rele()1076 * calls. The pag_buf_lock being taken on the last reference only1077 * serialises against racing lookups in xfs_buf_find(). IOWs, the second1078 * to last reference we drop here is not serialised against the last1079 * reference until we take bp->b_lock. Hence if we don't grab b_lock1080 * first, the last "release" reference can win the race to the lock and1081 * free the buffer before the second-to-last reference is processed,1082 * leading to a use-after-free scenario.1083 */1084 spin_lock(&bp->b_lock);1085 release = atomic_dec_and_lock(&bp->b_hold, &bch->bc_lock);1086 if (!release) {1087 /*1088 * Drop the in-flight state if the buffer is already on the LRU1089 * and it holds the only reference. This is racy because we1090 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT1091 * ensures the decrement occurs only once per-buf.1092 */1093 if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))1094 __xfs_buf_ioacct_dec(bp);1095 goto out_unlock;1096 }1097 1098 /* the last reference has been dropped ... */1099 __xfs_buf_ioacct_dec(bp);1100 if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {1101 /*1102 * If the buffer is added to the LRU take a new reference to the1103 * buffer for the LRU and clear the (now stale) dispose list1104 * state flag1105 */1106 if (list_lru_add_obj(&btp->bt_lru, &bp->b_lru)) {1107 bp->b_state &= ~XFS_BSTATE_DISPOSE;1108 atomic_inc(&bp->b_hold);1109 }1110 spin_unlock(&bch->bc_lock);1111 } else {1112 /*1113 * most of the time buffers will already be removed from the1114 * LRU, so optimise that case by checking for the1115 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer1116 * was on was the disposal list1117 */1118 if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {1119 list_lru_del_obj(&btp->bt_lru, &bp->b_lru);1120 } else {1121 ASSERT(list_empty(&bp->b_lru));1122 }1123 1124 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));1125 rhashtable_remove_fast(&bch->bc_hash, &bp->b_rhash_head,1126 xfs_buf_hash_params);1127 spin_unlock(&bch->bc_lock);1128 if (pag)1129 xfs_perag_put(pag);1130 freebuf = true;1131 }1132 1133out_unlock:1134 spin_unlock(&bp->b_lock);1135 1136 if (freebuf)1137 xfs_buf_free(bp);1138}1139 1140/*1141 * Release a hold on the specified buffer.1142 */1143void1144xfs_buf_rele(1145 struct xfs_buf *bp)1146{1147 trace_xfs_buf_rele(bp, _RET_IP_);1148 if (xfs_buf_is_uncached(bp))1149 xfs_buf_rele_uncached(bp);1150 else1151 xfs_buf_rele_cached(bp);1152}1153 1154/*1155 * Lock a buffer object, if it is not already locked.1156 *1157 * If we come across a stale, pinned, locked buffer, we know that we are1158 * being asked to lock a buffer that has been reallocated. Because it is1159 * pinned, we know that the log has not been pushed to disk and hence it1160 * will still be locked. Rather than continuing to have trylock attempts1161 * fail until someone else pushes the log, push it ourselves before1162 * returning. This means that the xfsaild will not get stuck trying1163 * to push on stale inode buffers.1164 */1165int1166xfs_buf_trylock(1167 struct xfs_buf *bp)1168{1169 int locked;1170 1171 locked = down_trylock(&bp->b_sema) == 0;1172 if (locked)1173 trace_xfs_buf_trylock(bp, _RET_IP_);1174 else1175 trace_xfs_buf_trylock_fail(bp, _RET_IP_);1176 return locked;1177}1178 1179/*1180 * Lock a buffer object.1181 *1182 * If we come across a stale, pinned, locked buffer, we know that we1183 * are being asked to lock a buffer that has been reallocated. Because1184 * it is pinned, we know that the log has not been pushed to disk and1185 * hence it will still be locked. Rather than sleeping until someone1186 * else pushes the log, push it ourselves before trying to get the lock.1187 */1188void1189xfs_buf_lock(1190 struct xfs_buf *bp)1191{1192 trace_xfs_buf_lock(bp, _RET_IP_);1193 1194 if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))1195 xfs_log_force(bp->b_mount, 0);1196 down(&bp->b_sema);1197 1198 trace_xfs_buf_lock_done(bp, _RET_IP_);1199}1200 1201void1202xfs_buf_unlock(1203 struct xfs_buf *bp)1204{1205 ASSERT(xfs_buf_islocked(bp));1206 1207 up(&bp->b_sema);1208 trace_xfs_buf_unlock(bp, _RET_IP_);1209}1210 1211STATIC void1212xfs_buf_wait_unpin(1213 struct xfs_buf *bp)1214{1215 DECLARE_WAITQUEUE (wait, current);1216 1217 if (atomic_read(&bp->b_pin_count) == 0)1218 return;1219 1220 add_wait_queue(&bp->b_waiters, &wait);1221 for (;;) {1222 set_current_state(TASK_UNINTERRUPTIBLE);1223 if (atomic_read(&bp->b_pin_count) == 0)1224 break;1225 io_schedule();1226 }1227 remove_wait_queue(&bp->b_waiters, &wait);1228 set_current_state(TASK_RUNNING);1229}1230 1231static void1232xfs_buf_ioerror_alert_ratelimited(1233 struct xfs_buf *bp)1234{1235 static unsigned long lasttime;1236 static struct xfs_buftarg *lasttarg;1237 1238 if (bp->b_target != lasttarg ||1239 time_after(jiffies, (lasttime + 5*HZ))) {1240 lasttime = jiffies;1241 xfs_buf_ioerror_alert(bp, __this_address);1242 }1243 lasttarg = bp->b_target;1244}1245 1246/*1247 * Account for this latest trip around the retry handler, and decide if1248 * we've failed enough times to constitute a permanent failure.1249 */1250static bool1251xfs_buf_ioerror_permanent(1252 struct xfs_buf *bp,1253 struct xfs_error_cfg *cfg)1254{1255 struct xfs_mount *mp = bp->b_mount;1256 1257 if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&1258 ++bp->b_retries > cfg->max_retries)1259 return true;1260 if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&1261 time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))1262 return true;1263 1264 /* At unmount we may treat errors differently */1265 if (xfs_is_unmounting(mp) && mp->m_fail_unmount)1266 return true;1267 1268 return false;1269}1270 1271/*1272 * On a sync write or shutdown we just want to stale the buffer and let the1273 * caller handle the error in bp->b_error appropriately.1274 *1275 * If the write was asynchronous then no one will be looking for the error. If1276 * this is the first failure of this type, clear the error state and write the1277 * buffer out again. This means we always retry an async write failure at least1278 * once, but we also need to set the buffer up to behave correctly now for1279 * repeated failures.1280 *1281 * If we get repeated async write failures, then we take action according to the1282 * error configuration we have been set up to use.1283 *1284 * Returns true if this function took care of error handling and the caller must1285 * not touch the buffer again. Return false if the caller should proceed with1286 * normal I/O completion handling.1287 */1288static bool1289xfs_buf_ioend_handle_error(1290 struct xfs_buf *bp)1291{1292 struct xfs_mount *mp = bp->b_mount;1293 struct xfs_error_cfg *cfg;1294 1295 /*1296 * If we've already shutdown the journal because of I/O errors, there's1297 * no point in giving this a retry.1298 */1299 if (xlog_is_shutdown(mp->m_log))1300 goto out_stale;1301 1302 xfs_buf_ioerror_alert_ratelimited(bp);1303 1304 /*1305 * We're not going to bother about retrying this during recovery.1306 * One strike!1307 */1308 if (bp->b_flags & _XBF_LOGRECOVERY) {1309 xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);1310 return false;1311 }1312 1313 /*1314 * Synchronous writes will have callers process the error.1315 */1316 if (!(bp->b_flags & XBF_ASYNC))1317 goto out_stale;1318 1319 trace_xfs_buf_iodone_async(bp, _RET_IP_);1320 1321 cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);1322 if (bp->b_last_error != bp->b_error ||1323 !(bp->b_flags & (XBF_STALE | XBF_WRITE_FAIL))) {1324 bp->b_last_error = bp->b_error;1325 if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&1326 !bp->b_first_retry_time)1327 bp->b_first_retry_time = jiffies;1328 goto resubmit;1329 }1330 1331 /*1332 * Permanent error - we need to trigger a shutdown if we haven't already1333 * to indicate that inconsistency will result from this action.1334 */1335 if (xfs_buf_ioerror_permanent(bp, cfg)) {1336 xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);1337 goto out_stale;1338 }1339 1340 /* Still considered a transient error. Caller will schedule retries. */1341 if (bp->b_flags & _XBF_INODES)1342 xfs_buf_inode_io_fail(bp);1343 else if (bp->b_flags & _XBF_DQUOTS)1344 xfs_buf_dquot_io_fail(bp);1345 else1346 ASSERT(list_empty(&bp->b_li_list));1347 xfs_buf_ioerror(bp, 0);1348 xfs_buf_relse(bp);1349 return true;1350 1351resubmit:1352 xfs_buf_ioerror(bp, 0);1353 bp->b_flags |= (XBF_DONE | XBF_WRITE_FAIL);1354 xfs_buf_submit(bp);1355 return true;1356out_stale:1357 xfs_buf_stale(bp);1358 bp->b_flags |= XBF_DONE;1359 bp->b_flags &= ~XBF_WRITE;1360 trace_xfs_buf_error_relse(bp, _RET_IP_);1361 return false;1362}1363 1364static void1365xfs_buf_ioend(1366 struct xfs_buf *bp)1367{1368 trace_xfs_buf_iodone(bp, _RET_IP_);1369 1370 /*1371 * Pull in IO completion errors now. We are guaranteed to be running1372 * single threaded, so we don't need the lock to read b_io_error.1373 */1374 if (!bp->b_error && bp->b_io_error)1375 xfs_buf_ioerror(bp, bp->b_io_error);1376 1377 if (bp->b_flags & XBF_READ) {1378 if (!bp->b_error && bp->b_ops)1379 bp->b_ops->verify_read(bp);1380 if (!bp->b_error)1381 bp->b_flags |= XBF_DONE;1382 } else {1383 if (!bp->b_error) {1384 bp->b_flags &= ~XBF_WRITE_FAIL;1385 bp->b_flags |= XBF_DONE;1386 }1387 1388 if (unlikely(bp->b_error) && xfs_buf_ioend_handle_error(bp))1389 return;1390 1391 /* clear the retry state */1392 bp->b_last_error = 0;1393 bp->b_retries = 0;1394 bp->b_first_retry_time = 0;1395 1396 /*1397 * Note that for things like remote attribute buffers, there may1398 * not be a buffer log item here, so processing the buffer log1399 * item must remain optional.1400 */1401 if (bp->b_log_item)1402 xfs_buf_item_done(bp);1403 1404 if (bp->b_flags & _XBF_INODES)1405 xfs_buf_inode_iodone(bp);1406 else if (bp->b_flags & _XBF_DQUOTS)1407 xfs_buf_dquot_iodone(bp);1408 1409 }1410 1411 bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD |1412 _XBF_LOGRECOVERY);1413 1414 if (bp->b_flags & XBF_ASYNC)1415 xfs_buf_relse(bp);1416 else1417 complete(&bp->b_iowait);1418}1419 1420static void1421xfs_buf_ioend_work(1422 struct work_struct *work)1423{1424 struct xfs_buf *bp =1425 container_of(work, struct xfs_buf, b_ioend_work);1426 1427 xfs_buf_ioend(bp);1428}1429 1430static void1431xfs_buf_ioend_async(1432 struct xfs_buf *bp)1433{1434 INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);1435 queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);1436}1437 1438void1439__xfs_buf_ioerror(1440 struct xfs_buf *bp,1441 int error,1442 xfs_failaddr_t failaddr)1443{1444 ASSERT(error <= 0 && error >= -1000);1445 bp->b_error = error;1446 trace_xfs_buf_ioerror(bp, error, failaddr);1447}1448 1449void1450xfs_buf_ioerror_alert(1451 struct xfs_buf *bp,1452 xfs_failaddr_t func)1453{1454 xfs_buf_alert_ratelimited(bp, "XFS: metadata IO error",1455 "metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",1456 func, (uint64_t)xfs_buf_daddr(bp),1457 bp->b_length, -bp->b_error);1458}1459 1460/*1461 * To simulate an I/O failure, the buffer must be locked and held with at least1462 * three references. The LRU reference is dropped by the stale call. The buf1463 * item reference is dropped via ioend processing. The third reference is owned1464 * by the caller and is dropped on I/O completion if the buffer is XBF_ASYNC.1465 */1466void1467xfs_buf_ioend_fail(1468 struct xfs_buf *bp)1469{1470 bp->b_flags &= ~XBF_DONE;1471 xfs_buf_stale(bp);1472 xfs_buf_ioerror(bp, -EIO);1473 xfs_buf_ioend(bp);1474}1475 1476int1477xfs_bwrite(1478 struct xfs_buf *bp)1479{1480 int error;1481 1482 ASSERT(xfs_buf_islocked(bp));1483 1484 bp->b_flags |= XBF_WRITE;1485 bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |1486 XBF_DONE);1487 1488 error = xfs_buf_submit(bp);1489 if (error)1490 xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);1491 return error;1492}1493 1494static void1495xfs_buf_bio_end_io(1496 struct bio *bio)1497{1498 struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private;1499 1500 if (!bio->bi_status &&1501 (bp->b_flags & XBF_WRITE) && (bp->b_flags & XBF_ASYNC) &&1502 XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_IOERROR))1503 bio->bi_status = BLK_STS_IOERR;1504 1505 /*1506 * don't overwrite existing errors - otherwise we can lose errors on1507 * buffers that require multiple bios to complete.1508 */1509 if (bio->bi_status) {1510 int error = blk_status_to_errno(bio->bi_status);1511 1512 cmpxchg(&bp->b_io_error, 0, error);1513 }1514 1515 if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))1516 invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));1517 1518 if (atomic_dec_and_test(&bp->b_io_remaining) == 1)1519 xfs_buf_ioend_async(bp);1520 bio_put(bio);1521}1522 1523static void1524xfs_buf_ioapply_map(1525 struct xfs_buf *bp,1526 int map,1527 int *buf_offset,1528 int *count,1529 blk_opf_t op)1530{1531 int page_index;1532 unsigned int total_nr_pages = bp->b_page_count;1533 int nr_pages;1534 struct bio *bio;1535 sector_t sector = bp->b_maps[map].bm_bn;1536 int size;1537 int offset;1538 1539 /* skip the pages in the buffer before the start offset */1540 page_index = 0;1541 offset = *buf_offset;1542 while (offset >= PAGE_SIZE) {1543 page_index++;1544 offset -= PAGE_SIZE;1545 }1546 1547 /*1548 * Limit the IO size to the length of the current vector, and update the1549 * remaining IO count for the next time around.1550 */1551 size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);1552 *count -= size;1553 *buf_offset += size;1554 1555next_chunk:1556 atomic_inc(&bp->b_io_remaining);1557 nr_pages = bio_max_segs(total_nr_pages);1558 1559 bio = bio_alloc(bp->b_target->bt_bdev, nr_pages, op, GFP_NOIO);1560 bio->bi_iter.bi_sector = sector;1561 bio->bi_end_io = xfs_buf_bio_end_io;1562 bio->bi_private = bp;1563 1564 for (; size && nr_pages; nr_pages--, page_index++) {1565 int rbytes, nbytes = PAGE_SIZE - offset;1566 1567 if (nbytes > size)1568 nbytes = size;1569 1570 rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,1571 offset);1572 if (rbytes < nbytes)1573 break;1574 1575 offset = 0;1576 sector += BTOBB(nbytes);1577 size -= nbytes;1578 total_nr_pages--;1579 }1580 1581 if (likely(bio->bi_iter.bi_size)) {1582 if (xfs_buf_is_vmapped(bp)) {1583 flush_kernel_vmap_range(bp->b_addr,1584 xfs_buf_vmap_len(bp));1585 }1586 submit_bio(bio);1587 if (size)1588 goto next_chunk;1589 } else {1590 /*1591 * This is guaranteed not to be the last io reference count1592 * because the caller (xfs_buf_submit) holds a count itself.1593 */1594 atomic_dec(&bp->b_io_remaining);1595 xfs_buf_ioerror(bp, -EIO);1596 bio_put(bio);1597 }1598 1599}1600 1601STATIC void1602_xfs_buf_ioapply(1603 struct xfs_buf *bp)1604{1605 struct blk_plug plug;1606 blk_opf_t op;1607 int offset;1608 int size;1609 int i;1610 1611 /*1612 * Make sure we capture only current IO errors rather than stale errors1613 * left over from previous use of the buffer (e.g. failed readahead).1614 */1615 bp->b_error = 0;1616 1617 if (bp->b_flags & XBF_WRITE) {1618 op = REQ_OP_WRITE;1619 1620 /*1621 * Run the write verifier callback function if it exists. If1622 * this function fails it will mark the buffer with an error and1623 * the IO should not be dispatched.1624 */1625 if (bp->b_ops) {1626 bp->b_ops->verify_write(bp);1627 if (bp->b_error) {1628 xfs_force_shutdown(bp->b_mount,1629 SHUTDOWN_CORRUPT_INCORE);1630 return;1631 }1632 } else if (bp->b_rhash_key != XFS_BUF_DADDR_NULL) {1633 struct xfs_mount *mp = bp->b_mount;1634 1635 /*1636 * non-crc filesystems don't attach verifiers during1637 * log recovery, so don't warn for such filesystems.1638 */1639 if (xfs_has_crc(mp)) {1640 xfs_warn(mp,1641 "%s: no buf ops on daddr 0x%llx len %d",1642 __func__, xfs_buf_daddr(bp),1643 bp->b_length);1644 xfs_hex_dump(bp->b_addr,1645 XFS_CORRUPTION_DUMP_LEN);1646 dump_stack();1647 }1648 }1649 } else {1650 op = REQ_OP_READ;1651 if (bp->b_flags & XBF_READ_AHEAD)1652 op |= REQ_RAHEAD;1653 }1654 1655 /* we only use the buffer cache for meta-data */1656 op |= REQ_META;1657 1658 /* in-memory targets are directly mapped, no IO required. */1659 if (xfs_buftarg_is_mem(bp->b_target)) {1660 xfs_buf_ioend(bp);1661 return;1662 }1663 1664 /*1665 * Walk all the vectors issuing IO on them. Set up the initial offset1666 * into the buffer and the desired IO size before we start -1667 * _xfs_buf_ioapply_vec() will modify them appropriately for each1668 * subsequent call.1669 */1670 offset = bp->b_offset;1671 size = BBTOB(bp->b_length);1672 blk_start_plug(&plug);1673 for (i = 0; i < bp->b_map_count; i++) {1674 xfs_buf_ioapply_map(bp, i, &offset, &size, op);1675 if (bp->b_error)1676 break;1677 if (size <= 0)1678 break; /* all done */1679 }1680 blk_finish_plug(&plug);1681}1682 1683/*1684 * Wait for I/O completion of a sync buffer and return the I/O error code.1685 */1686static int1687xfs_buf_iowait(1688 struct xfs_buf *bp)1689{1690 ASSERT(!(bp->b_flags & XBF_ASYNC));1691 1692 trace_xfs_buf_iowait(bp, _RET_IP_);1693 wait_for_completion(&bp->b_iowait);1694 trace_xfs_buf_iowait_done(bp, _RET_IP_);1695 1696 return bp->b_error;1697}1698 1699/*1700 * Buffer I/O submission path, read or write. Asynchronous submission transfers1701 * the buffer lock ownership and the current reference to the IO. It is not1702 * safe to reference the buffer after a call to this function unless the caller1703 * holds an additional reference itself.1704 */1705static int1706__xfs_buf_submit(1707 struct xfs_buf *bp,1708 bool wait)1709{1710 int error = 0;1711 1712 trace_xfs_buf_submit(bp, _RET_IP_);1713 1714 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));1715 1716 /*1717 * On log shutdown we stale and complete the buffer immediately. We can1718 * be called to read the superblock before the log has been set up, so1719 * be careful checking the log state.1720 *1721 * Checking the mount shutdown state here can result in the log tail1722 * moving inappropriately on disk as the log may not yet be shut down.1723 * i.e. failing this buffer on mount shutdown can remove it from the AIL1724 * and move the tail of the log forwards without having written this1725 * buffer to disk. This corrupts the log tail state in memory, and1726 * because the log may not be shut down yet, it can then be propagated1727 * to disk before the log is shutdown. Hence we check log shutdown1728 * state here rather than mount state to avoid corrupting the log tail1729 * on shutdown.1730 */1731 if (bp->b_mount->m_log &&1732 xlog_is_shutdown(bp->b_mount->m_log)) {1733 xfs_buf_ioend_fail(bp);1734 return -EIO;1735 }1736 1737 /*1738 * Grab a reference so the buffer does not go away underneath us. For1739 * async buffers, I/O completion drops the callers reference, which1740 * could occur before submission returns.1741 */1742 xfs_buf_hold(bp);1743 1744 if (bp->b_flags & XBF_WRITE)1745 xfs_buf_wait_unpin(bp);1746 1747 /* clear the internal error state to avoid spurious errors */1748 bp->b_io_error = 0;1749 1750 /*1751 * Set the count to 1 initially, this will stop an I/O completion1752 * callout which happens before we have started all the I/O from calling1753 * xfs_buf_ioend too early.1754 */1755 atomic_set(&bp->b_io_remaining, 1);1756 if (bp->b_flags & XBF_ASYNC)1757 xfs_buf_ioacct_inc(bp);1758 _xfs_buf_ioapply(bp);1759 1760 /*1761 * If _xfs_buf_ioapply failed, we can get back here with only the IO1762 * reference we took above. If we drop it to zero, run completion so1763 * that we don't return to the caller with completion still pending.1764 */1765 if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {1766 if (bp->b_error || !(bp->b_flags & XBF_ASYNC))1767 xfs_buf_ioend(bp);1768 else1769 xfs_buf_ioend_async(bp);1770 }1771 1772 if (wait)1773 error = xfs_buf_iowait(bp);1774 1775 /*1776 * Release the hold that keeps the buffer referenced for the entire1777 * I/O. Note that if the buffer is async, it is not safe to reference1778 * after this release.1779 */1780 xfs_buf_rele(bp);1781 return error;1782}1783 1784void *1785xfs_buf_offset(1786 struct xfs_buf *bp,1787 size_t offset)1788{1789 struct page *page;1790 1791 if (bp->b_addr)1792 return bp->b_addr + offset;1793 1794 page = bp->b_pages[offset >> PAGE_SHIFT];1795 return page_address(page) + (offset & (PAGE_SIZE-1));1796}1797 1798void1799xfs_buf_zero(1800 struct xfs_buf *bp,1801 size_t boff,1802 size_t bsize)1803{1804 size_t bend;1805 1806 bend = boff + bsize;1807 while (boff < bend) {1808 struct page *page;1809 int page_index, page_offset, csize;1810 1811 page_index = (boff + bp->b_offset) >> PAGE_SHIFT;1812 page_offset = (boff + bp->b_offset) & ~PAGE_MASK;1813 page = bp->b_pages[page_index];1814 csize = min_t(size_t, PAGE_SIZE - page_offset,1815 BBTOB(bp->b_length) - boff);1816 1817 ASSERT((csize + page_offset) <= PAGE_SIZE);1818 1819 memset(page_address(page) + page_offset, 0, csize);1820 1821 boff += csize;1822 }1823}1824 1825/*1826 * Log a message about and stale a buffer that a caller has decided is corrupt.1827 *1828 * This function should be called for the kinds of metadata corruption that1829 * cannot be detect from a verifier, such as incorrect inter-block relationship1830 * data. Do /not/ call this function from a verifier function.1831 *1832 * The buffer must be XBF_DONE prior to the call. Afterwards, the buffer will1833 * be marked stale, but b_error will not be set. The caller is responsible for1834 * releasing the buffer or fixing it.1835 */1836void1837__xfs_buf_mark_corrupt(1838 struct xfs_buf *bp,1839 xfs_failaddr_t fa)1840{1841 ASSERT(bp->b_flags & XBF_DONE);1842 1843 xfs_buf_corruption_error(bp, fa);1844 xfs_buf_stale(bp);1845}1846 1847/*1848 * Handling of buffer targets (buftargs).1849 */1850 1851/*1852 * Wait for any bufs with callbacks that have been submitted but have not yet1853 * returned. These buffers will have an elevated hold count, so wait on those1854 * while freeing all the buffers only held by the LRU.1855 */1856static enum lru_status1857xfs_buftarg_drain_rele(1858 struct list_head *item,1859 struct list_lru_one *lru,1860 spinlock_t *lru_lock,1861 void *arg)1862 1863{1864 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);1865 struct list_head *dispose = arg;1866 1867 if (atomic_read(&bp->b_hold) > 1) {1868 /* need to wait, so skip it this pass */1869 trace_xfs_buf_drain_buftarg(bp, _RET_IP_);1870 return LRU_SKIP;1871 }1872 if (!spin_trylock(&bp->b_lock))1873 return LRU_SKIP;1874 1875 /*1876 * clear the LRU reference count so the buffer doesn't get1877 * ignored in xfs_buf_rele().1878 */1879 atomic_set(&bp->b_lru_ref, 0);1880 bp->b_state |= XFS_BSTATE_DISPOSE;1881 list_lru_isolate_move(lru, item, dispose);1882 spin_unlock(&bp->b_lock);1883 return LRU_REMOVED;1884}1885 1886/*1887 * Wait for outstanding I/O on the buftarg to complete.1888 */1889void1890xfs_buftarg_wait(1891 struct xfs_buftarg *btp)1892{1893 /*1894 * First wait on the buftarg I/O count for all in-flight buffers to be1895 * released. This is critical as new buffers do not make the LRU until1896 * they are released.1897 *1898 * Next, flush the buffer workqueue to ensure all completion processing1899 * has finished. Just waiting on buffer locks is not sufficient for1900 * async IO as the reference count held over IO is not released until1901 * after the buffer lock is dropped. Hence we need to ensure here that1902 * all reference counts have been dropped before we start walking the1903 * LRU list.1904 */1905 while (percpu_counter_sum(&btp->bt_io_count))1906 delay(100);1907 flush_workqueue(btp->bt_mount->m_buf_workqueue);1908}1909 1910void1911xfs_buftarg_drain(1912 struct xfs_buftarg *btp)1913{1914 LIST_HEAD(dispose);1915 int loop = 0;1916 bool write_fail = false;1917 1918 xfs_buftarg_wait(btp);1919 1920 /* loop until there is nothing left on the lru list. */1921 while (list_lru_count(&btp->bt_lru)) {1922 list_lru_walk(&btp->bt_lru, xfs_buftarg_drain_rele,1923 &dispose, LONG_MAX);1924 1925 while (!list_empty(&dispose)) {1926 struct xfs_buf *bp;1927 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);1928 list_del_init(&bp->b_lru);1929 if (bp->b_flags & XBF_WRITE_FAIL) {1930 write_fail = true;1931 xfs_buf_alert_ratelimited(bp,1932 "XFS: Corruption Alert",1933"Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",1934 (long long)xfs_buf_daddr(bp));1935 }1936 xfs_buf_rele(bp);1937 }1938 if (loop++ != 0)1939 delay(100);1940 }1941 1942 /*1943 * If one or more failed buffers were freed, that means dirty metadata1944 * was thrown away. This should only ever happen after I/O completion1945 * handling has elevated I/O error(s) to permanent failures and shuts1946 * down the journal.1947 */1948 if (write_fail) {1949 ASSERT(xlog_is_shutdown(btp->bt_mount->m_log));1950 xfs_alert(btp->bt_mount,1951 "Please run xfs_repair to determine the extent of the problem.");1952 }1953}1954 1955static enum lru_status1956xfs_buftarg_isolate(1957 struct list_head *item,1958 struct list_lru_one *lru,1959 spinlock_t *lru_lock,1960 void *arg)1961{1962 struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru);1963 struct list_head *dispose = arg;1964 1965 /*1966 * we are inverting the lru lock/bp->b_lock here, so use a trylock.1967 * If we fail to get the lock, just skip it.1968 */1969 if (!spin_trylock(&bp->b_lock))1970 return LRU_SKIP;1971 /*1972 * Decrement the b_lru_ref count unless the value is already1973 * zero. If the value is already zero, we need to reclaim the1974 * buffer, otherwise it gets another trip through the LRU.1975 */1976 if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {1977 spin_unlock(&bp->b_lock);1978 return LRU_ROTATE;1979 }1980 1981 bp->b_state |= XFS_BSTATE_DISPOSE;1982 list_lru_isolate_move(lru, item, dispose);1983 spin_unlock(&bp->b_lock);1984 return LRU_REMOVED;1985}1986 1987static unsigned long1988xfs_buftarg_shrink_scan(1989 struct shrinker *shrink,1990 struct shrink_control *sc)1991{1992 struct xfs_buftarg *btp = shrink->private_data;1993 LIST_HEAD(dispose);1994 unsigned long freed;1995 1996 freed = list_lru_shrink_walk(&btp->bt_lru, sc,1997 xfs_buftarg_isolate, &dispose);1998 1999 while (!list_empty(&dispose)) {2000 struct xfs_buf *bp;2001 bp = list_first_entry(&dispose, struct xfs_buf, b_lru);2002 list_del_init(&bp->b_lru);2003 xfs_buf_rele(bp);2004 }2005 2006 return freed;2007}2008 2009static unsigned long2010xfs_buftarg_shrink_count(2011 struct shrinker *shrink,2012 struct shrink_control *sc)2013{2014 struct xfs_buftarg *btp = shrink->private_data;2015 return list_lru_shrink_count(&btp->bt_lru, sc);2016}2017 2018void2019xfs_destroy_buftarg(2020 struct xfs_buftarg *btp)2021{2022 shrinker_free(btp->bt_shrinker);2023 ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);2024 percpu_counter_destroy(&btp->bt_io_count);2025 list_lru_destroy(&btp->bt_lru);2026}2027 2028void2029xfs_free_buftarg(2030 struct xfs_buftarg *btp)2031{2032 xfs_destroy_buftarg(btp);2033 fs_put_dax(btp->bt_daxdev, btp->bt_mount);2034 /* the main block device is closed by kill_block_super */2035 if (btp->bt_bdev != btp->bt_mount->m_super->s_bdev)2036 bdev_fput(btp->bt_bdev_file);2037 kfree(btp);2038}2039 2040int2041xfs_setsize_buftarg(2042 struct xfs_buftarg *btp,2043 unsigned int sectorsize)2044{2045 /* Set up metadata sector size info */2046 btp->bt_meta_sectorsize = sectorsize;2047 btp->bt_meta_sectormask = sectorsize - 1;2048 2049 if (set_blocksize(btp->bt_bdev_file, sectorsize)) {2050 xfs_warn(btp->bt_mount,2051 "Cannot set_blocksize to %u on device %pg",2052 sectorsize, btp->bt_bdev);2053 return -EINVAL;2054 }2055 2056 return 0;2057}2058 2059int2060xfs_init_buftarg(2061 struct xfs_buftarg *btp,2062 size_t logical_sectorsize,2063 const char *descr)2064{2065 /* Set up device logical sector size mask */2066 btp->bt_logical_sectorsize = logical_sectorsize;2067 btp->bt_logical_sectormask = logical_sectorsize - 1;2068 2069 /*2070 * Buffer IO error rate limiting. Limit it to no more than 10 messages2071 * per 30 seconds so as to not spam logs too much on repeated errors.2072 */2073 ratelimit_state_init(&btp->bt_ioerror_rl, 30 * HZ,2074 DEFAULT_RATELIMIT_BURST);2075 2076 if (list_lru_init(&btp->bt_lru))2077 return -ENOMEM;2078 if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))2079 goto out_destroy_lru;2080 2081 btp->bt_shrinker =2082 shrinker_alloc(SHRINKER_NUMA_AWARE, "xfs-buf:%s", descr);2083 if (!btp->bt_shrinker)2084 goto out_destroy_io_count;2085 btp->bt_shrinker->count_objects = xfs_buftarg_shrink_count;2086 btp->bt_shrinker->scan_objects = xfs_buftarg_shrink_scan;2087 btp->bt_shrinker->private_data = btp;2088 shrinker_register(btp->bt_shrinker);2089 return 0;2090 2091out_destroy_io_count:2092 percpu_counter_destroy(&btp->bt_io_count);2093out_destroy_lru:2094 list_lru_destroy(&btp->bt_lru);2095 return -ENOMEM;2096}2097 2098struct xfs_buftarg *2099xfs_alloc_buftarg(2100 struct xfs_mount *mp,2101 struct file *bdev_file)2102{2103 struct xfs_buftarg *btp;2104 const struct dax_holder_operations *ops = NULL;2105 2106#if defined(CONFIG_FS_DAX) && defined(CONFIG_MEMORY_FAILURE)2107 ops = &xfs_dax_holder_operations;2108#endif2109 btp = kzalloc(sizeof(*btp), GFP_KERNEL | __GFP_NOFAIL);2110 2111 btp->bt_mount = mp;2112 btp->bt_bdev_file = bdev_file;2113 btp->bt_bdev = file_bdev(bdev_file);2114 btp->bt_dev = btp->bt_bdev->bd_dev;2115 btp->bt_daxdev = fs_dax_get_by_bdev(btp->bt_bdev, &btp->bt_dax_part_off,2116 mp, ops);2117 2118 /*2119 * When allocating the buftargs we have not yet read the super block and2120 * thus don't know the file system sector size yet.2121 */2122 if (xfs_setsize_buftarg(btp, bdev_logical_block_size(btp->bt_bdev)))2123 goto error_free;2124 if (xfs_init_buftarg(btp, bdev_logical_block_size(btp->bt_bdev),2125 mp->m_super->s_id))2126 goto error_free;2127 2128 return btp;2129 2130error_free:2131 kfree(btp);2132 return NULL;2133}2134 2135static inline void2136xfs_buf_list_del(2137 struct xfs_buf *bp)2138{2139 list_del_init(&bp->b_list);2140 wake_up_var(&bp->b_list);2141}2142 2143/*2144 * Cancel a delayed write list.2145 *2146 * Remove each buffer from the list, clear the delwri queue flag and drop the2147 * associated buffer reference.2148 */2149void2150xfs_buf_delwri_cancel(2151 struct list_head *list)2152{2153 struct xfs_buf *bp;2154 2155 while (!list_empty(list)) {2156 bp = list_first_entry(list, struct xfs_buf, b_list);2157 2158 xfs_buf_lock(bp);2159 bp->b_flags &= ~_XBF_DELWRI_Q;2160 xfs_buf_list_del(bp);2161 xfs_buf_relse(bp);2162 }2163}2164 2165/*2166 * Add a buffer to the delayed write list.2167 *2168 * This queues a buffer for writeout if it hasn't already been. Note that2169 * neither this routine nor the buffer list submission functions perform2170 * any internal synchronization. It is expected that the lists are thread-local2171 * to the callers.2172 *2173 * Returns true if we queued up the buffer, or false if it already had2174 * been on the buffer list.2175 */2176bool2177xfs_buf_delwri_queue(2178 struct xfs_buf *bp,2179 struct list_head *list)2180{2181 ASSERT(xfs_buf_islocked(bp));2182 ASSERT(!(bp->b_flags & XBF_READ));2183 2184 /*2185 * If the buffer is already marked delwri it already is queued up2186 * by someone else for imediate writeout. Just ignore it in that2187 * case.2188 */2189 if (bp->b_flags & _XBF_DELWRI_Q) {2190 trace_xfs_buf_delwri_queued(bp, _RET_IP_);2191 return false;2192 }2193 2194 trace_xfs_buf_delwri_queue(bp, _RET_IP_);2195 2196 /*2197 * If a buffer gets written out synchronously or marked stale while it2198 * is on a delwri list we lazily remove it. To do this, the other party2199 * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.2200 * It remains referenced and on the list. In a rare corner case it2201 * might get readded to a delwri list after the synchronous writeout, in2202 * which case we need just need to re-add the flag here.2203 */2204 bp->b_flags |= _XBF_DELWRI_Q;2205 if (list_empty(&bp->b_list)) {2206 atomic_inc(&bp->b_hold);2207 list_add_tail(&bp->b_list, list);2208 }2209 2210 return true;2211}2212 2213/*2214 * Queue a buffer to this delwri list as part of a data integrity operation.2215 * If the buffer is on any other delwri list, we'll wait for that to clear2216 * so that the caller can submit the buffer for IO and wait for the result.2217 * Callers must ensure the buffer is not already on the list.2218 */2219void2220xfs_buf_delwri_queue_here(2221 struct xfs_buf *bp,2222 struct list_head *buffer_list)2223{2224 /*2225 * We need this buffer to end up on the /caller's/ delwri list, not any2226 * old list. This can happen if the buffer is marked stale (which2227 * clears DELWRI_Q) after the AIL queues the buffer to its list but2228 * before the AIL has a chance to submit the list.2229 */2230 while (!list_empty(&bp->b_list)) {2231 xfs_buf_unlock(bp);2232 wait_var_event(&bp->b_list, list_empty(&bp->b_list));2233 xfs_buf_lock(bp);2234 }2235 2236 ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));2237 2238 xfs_buf_delwri_queue(bp, buffer_list);2239}2240 2241/*2242 * Compare function is more complex than it needs to be because2243 * the return value is only 32 bits and we are doing comparisons2244 * on 64 bit values2245 */2246static int2247xfs_buf_cmp(2248 void *priv,2249 const struct list_head *a,2250 const struct list_head *b)2251{2252 struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list);2253 struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);2254 xfs_daddr_t diff;2255 2256 diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;2257 if (diff < 0)2258 return -1;2259 if (diff > 0)2260 return 1;2261 return 0;2262}2263 2264/*2265 * Submit buffers for write. If wait_list is specified, the buffers are2266 * submitted using sync I/O and placed on the wait list such that the caller can2267 * iowait each buffer. Otherwise async I/O is used and the buffers are released2268 * at I/O completion time. In either case, buffers remain locked until I/O2269 * completes and the buffer is released from the queue.2270 */2271static int2272xfs_buf_delwri_submit_buffers(2273 struct list_head *buffer_list,2274 struct list_head *wait_list)2275{2276 struct xfs_buf *bp, *n;2277 int pinned = 0;2278 struct blk_plug plug;2279 2280 list_sort(NULL, buffer_list, xfs_buf_cmp);2281 2282 blk_start_plug(&plug);2283 list_for_each_entry_safe(bp, n, buffer_list, b_list) {2284 if (!wait_list) {2285 if (!xfs_buf_trylock(bp))2286 continue;2287 if (xfs_buf_ispinned(bp)) {2288 xfs_buf_unlock(bp);2289 pinned++;2290 continue;2291 }2292 } else {2293 xfs_buf_lock(bp);2294 }2295 2296 /*2297 * Someone else might have written the buffer synchronously or2298 * marked it stale in the meantime. In that case only the2299 * _XBF_DELWRI_Q flag got cleared, and we have to drop the2300 * reference and remove it from the list here.2301 */2302 if (!(bp->b_flags & _XBF_DELWRI_Q)) {2303 xfs_buf_list_del(bp);2304 xfs_buf_relse(bp);2305 continue;2306 }2307 2308 trace_xfs_buf_delwri_split(bp, _RET_IP_);2309 2310 /*2311 * If we have a wait list, each buffer (and associated delwri2312 * queue reference) transfers to it and is submitted2313 * synchronously. Otherwise, drop the buffer from the delwri2314 * queue and submit async.2315 */2316 bp->b_flags &= ~_XBF_DELWRI_Q;2317 bp->b_flags |= XBF_WRITE;2318 if (wait_list) {2319 bp->b_flags &= ~XBF_ASYNC;2320 list_move_tail(&bp->b_list, wait_list);2321 } else {2322 bp->b_flags |= XBF_ASYNC;2323 xfs_buf_list_del(bp);2324 }2325 __xfs_buf_submit(bp, false);2326 }2327 blk_finish_plug(&plug);2328 2329 return pinned;2330}2331 2332/*2333 * Write out a buffer list asynchronously.2334 *2335 * This will take the @buffer_list, write all non-locked and non-pinned buffers2336 * out and not wait for I/O completion on any of the buffers. This interface2337 * is only safely useable for callers that can track I/O completion by higher2338 * level means, e.g. AIL pushing as the @buffer_list is consumed in this2339 * function.2340 *2341 * Note: this function will skip buffers it would block on, and in doing so2342 * leaves them on @buffer_list so they can be retried on a later pass. As such,2343 * it is up to the caller to ensure that the buffer list is fully submitted or2344 * cancelled appropriately when they are finished with the list. Failure to2345 * cancel or resubmit the list until it is empty will result in leaked buffers2346 * at unmount time.2347 */2348int2349xfs_buf_delwri_submit_nowait(2350 struct list_head *buffer_list)2351{2352 return xfs_buf_delwri_submit_buffers(buffer_list, NULL);2353}2354 2355/*2356 * Write out a buffer list synchronously.2357 *2358 * This will take the @buffer_list, write all buffers out and wait for I/O2359 * completion on all of the buffers. @buffer_list is consumed by the function,2360 * so callers must have some other way of tracking buffers if they require such2361 * functionality.2362 */2363int2364xfs_buf_delwri_submit(2365 struct list_head *buffer_list)2366{2367 LIST_HEAD (wait_list);2368 int error = 0, error2;2369 struct xfs_buf *bp;2370 2371 xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);2372 2373 /* Wait for IO to complete. */2374 while (!list_empty(&wait_list)) {2375 bp = list_first_entry(&wait_list, struct xfs_buf, b_list);2376 2377 xfs_buf_list_del(bp);2378 2379 /*2380 * Wait on the locked buffer, check for errors and unlock and2381 * release the delwri queue reference.2382 */2383 error2 = xfs_buf_iowait(bp);2384 xfs_buf_relse(bp);2385 if (!error)2386 error = error2;2387 }2388 2389 return error;2390}2391 2392/*2393 * Push a single buffer on a delwri queue.2394 *2395 * The purpose of this function is to submit a single buffer of a delwri queue2396 * and return with the buffer still on the original queue. The waiting delwri2397 * buffer submission infrastructure guarantees transfer of the delwri queue2398 * buffer reference to a temporary wait list. We reuse this infrastructure to2399 * transfer the buffer back to the original queue.2400 *2401 * Note the buffer transitions from the queued state, to the submitted and wait2402 * listed state and back to the queued state during this call. The buffer2403 * locking and queue management logic between _delwri_pushbuf() and2404 * _delwri_queue() guarantee that the buffer cannot be queued to another list2405 * before returning.2406 */2407int2408xfs_buf_delwri_pushbuf(2409 struct xfs_buf *bp,2410 struct list_head *buffer_list)2411{2412 LIST_HEAD (submit_list);2413 int error;2414 2415 ASSERT(bp->b_flags & _XBF_DELWRI_Q);2416 2417 trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);2418 2419 /*2420 * Isolate the buffer to a new local list so we can submit it for I/O2421 * independently from the rest of the original list.2422 */2423 xfs_buf_lock(bp);2424 list_move(&bp->b_list, &submit_list);2425 xfs_buf_unlock(bp);2426 2427 /*2428 * Delwri submission clears the DELWRI_Q buffer flag and returns with2429 * the buffer on the wait list with the original reference. Rather than2430 * bounce the buffer from a local wait list back to the original list2431 * after I/O completion, reuse the original list as the wait list.2432 */2433 xfs_buf_delwri_submit_buffers(&submit_list, buffer_list);2434 2435 /*2436 * The buffer is now locked, under I/O and wait listed on the original2437 * delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and2438 * return with the buffer unlocked and on the original queue.2439 */2440 error = xfs_buf_iowait(bp);2441 bp->b_flags |= _XBF_DELWRI_Q;2442 xfs_buf_unlock(bp);2443 2444 return error;2445}2446 2447void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)2448{2449 /*2450 * Set the lru reference count to 0 based on the error injection tag.2451 * This allows userspace to disrupt buffer caching for debug/testing2452 * purposes.2453 */2454 if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))2455 lru_ref = 0;2456 2457 atomic_set(&bp->b_lru_ref, lru_ref);2458}2459 2460/*2461 * Verify an on-disk magic value against the magic value specified in the2462 * verifier structure. The verifier magic is in disk byte order so the caller is2463 * expected to pass the value directly from disk.2464 */2465bool2466xfs_verify_magic(2467 struct xfs_buf *bp,2468 __be32 dmagic)2469{2470 struct xfs_mount *mp = bp->b_mount;2471 int idx;2472 2473 idx = xfs_has_crc(mp);2474 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))2475 return false;2476 return dmagic == bp->b_ops->magic[idx];2477}2478/*2479 * Verify an on-disk magic value against the magic value specified in the2480 * verifier structure. The verifier magic is in disk byte order so the caller is2481 * expected to pass the value directly from disk.2482 */2483bool2484xfs_verify_magic16(2485 struct xfs_buf *bp,2486 __be16 dmagic)2487{2488 struct xfs_mount *mp = bp->b_mount;2489 int idx;2490 2491 idx = xfs_has_crc(mp);2492 if (WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))2493 return false;2494 return dmagic == bp->b_ops->magic16[idx];2495}2496