/* * Copyright (c) 2000-2006 Silicon Graphics, Inc. * All Rights Reserved. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation. * * This program is distributed in the hope that it would be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #include "xfs.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "xfs_format.h" #include "xfs_log_format.h" #include "xfs_trans_resv.h" #include "xfs_sb.h" #include "xfs_mount.h" #include "xfs_trace.h" #include "xfs_log.h" static kmem_zone_t *xfs_buf_zone; #ifdef XFS_BUF_LOCK_TRACKING # define XB_SET_OWNER(bp) ((bp)->b_last_holder = current->pid) # define XB_CLEAR_OWNER(bp) ((bp)->b_last_holder = -1) # define XB_GET_OWNER(bp) ((bp)->b_last_holder) #else # define XB_SET_OWNER(bp) do { } while (0) # define XB_CLEAR_OWNER(bp) do { } while (0) # define XB_GET_OWNER(bp) do { } while (0) #endif #define xb_to_gfp(flags) \ ((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : GFP_NOFS) | __GFP_NOWARN) static inline int xfs_buf_is_vmapped( struct xfs_buf *bp) { /* * Return true if the buffer is vmapped. * * b_addr is null if the buffer is not mapped, but the code is clever * enough to know it doesn't have to map a single page, so the check has * to be both for b_addr and bp->b_page_count > 1. */ return bp->b_addr && bp->b_page_count > 1; } static inline int xfs_buf_vmap_len( struct xfs_buf *bp) { return (bp->b_page_count * PAGE_SIZE) - bp->b_offset; } /* * When we mark a buffer stale, we remove the buffer from the LRU and clear the * b_lru_ref count so that the buffer is freed immediately when the buffer * reference count falls to zero. If the buffer is already on the LRU, we need * to remove the reference that LRU holds on the buffer. * * This prevents build-up of stale buffers on the LRU. */ void xfs_buf_stale( struct xfs_buf *bp) { ASSERT(xfs_buf_islocked(bp)); bp->b_flags |= XBF_STALE; /* * Clear the delwri status so that a delwri queue walker will not * flush this buffer to disk now that it is stale. The delwri queue has * a reference to the buffer, so this is safe to do. */ bp->b_flags &= ~_XBF_DELWRI_Q; spin_lock(&bp->b_lock); atomic_set(&bp->b_lru_ref, 0); if (!(bp->b_state & XFS_BSTATE_DISPOSE) && (list_lru_del(&bp->b_target->bt_lru, &bp->b_lru))) atomic_dec(&bp->b_hold); ASSERT(atomic_read(&bp->b_hold) >= 1); spin_unlock(&bp->b_lock); } static int xfs_buf_get_maps( struct xfs_buf *bp, int map_count) { ASSERT(bp->b_maps == NULL); bp->b_map_count = map_count; if (map_count == 1) { bp->b_maps = &bp->__b_map; return 0; } bp->b_maps = kmem_zalloc(map_count * sizeof(struct xfs_buf_map), KM_NOFS); if (!bp->b_maps) return -ENOMEM; return 0; } /* * Frees b_pages if it was allocated. */ static void xfs_buf_free_maps( struct xfs_buf *bp) { if (bp->b_maps != &bp->__b_map) { kmem_free(bp->b_maps); bp->b_maps = NULL; } } struct xfs_buf * _xfs_buf_alloc( struct xfs_buftarg *target, struct xfs_buf_map *map, int nmaps, xfs_buf_flags_t flags) { struct xfs_buf *bp; int error; int i; bp = kmem_zone_zalloc(xfs_buf_zone, KM_NOFS); if (unlikely(!bp)) return NULL; /* * We don't want certain flags to appear in b_flags unless they are * specifically set by later operations on the buffer. */ flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD); atomic_set(&bp->b_hold, 1); atomic_set(&bp->b_lru_ref, 1); init_completion(&bp->b_iowait); INIT_LIST_HEAD(&bp->b_lru); INIT_LIST_HEAD(&bp->b_list); RB_CLEAR_NODE(&bp->b_rbnode); sema_init(&bp->b_sema, 0); /* held, no waiters */ spin_lock_init(&bp->b_lock); XB_SET_OWNER(bp); bp->b_target = target; bp->b_flags = flags; /* * Set length and io_length to the same value initially. * I/O routines should use io_length, which will be the same in * most cases but may be reset (e.g. XFS recovery). */ error = xfs_buf_get_maps(bp, nmaps); if (error) { kmem_zone_free(xfs_buf_zone, bp); return NULL; } bp->b_bn = map[0].bm_bn; bp->b_length = 0; for (i = 0; i < nmaps; i++) { bp->b_maps[i].bm_bn = map[i].bm_bn; bp->b_maps[i].bm_len = map[i].bm_len; bp->b_length += map[i].bm_len; } bp->b_io_length = bp->b_length; atomic_set(&bp->b_pin_count, 0); init_waitqueue_head(&bp->b_waiters); XFS_STATS_INC(target->bt_mount, xb_create); trace_xfs_buf_init(bp, _RET_IP_); return bp; } /* * Allocate a page array capable of holding a specified number * of pages, and point the page buf at it. */ STATIC int _xfs_buf_get_pages( xfs_buf_t *bp, int page_count) { /* Make sure that we have a page list */ if (bp->b_pages == NULL) { bp->b_page_count = page_count; if (page_count <= XB_PAGES) { bp->b_pages = bp->b_page_array; } else { bp->b_pages = kmem_alloc(sizeof(struct page *) * page_count, KM_NOFS); if (bp->b_pages == NULL) return -ENOMEM; } memset(bp->b_pages, 0, sizeof(struct page *) * page_count); } return 0; } /* * Frees b_pages if it was allocated. */ STATIC void _xfs_buf_free_pages( xfs_buf_t *bp) { if (bp->b_pages != bp->b_page_array) { kmem_free(bp->b_pages); bp->b_pages = NULL; } } /* * Releases the specified buffer. * * The modification state of any associated pages is left unchanged. * The buffer must not be on any hash - use xfs_buf_rele instead for * hashed and refcounted buffers */ void xfs_buf_free( xfs_buf_t *bp) { trace_xfs_buf_free(bp, _RET_IP_); ASSERT(list_empty(&bp->b_lru)); if (bp->b_flags & _XBF_PAGES) { uint i; if (xfs_buf_is_vmapped(bp)) vm_unmap_ram(bp->b_addr - bp->b_offset, bp->b_page_count); for (i = 0; i < bp->b_page_count; i++) { struct page *page = bp->b_pages[i]; __free_page(page); } } else if (bp->b_flags & _XBF_KMEM) kmem_free(bp->b_addr); _xfs_buf_free_pages(bp); xfs_buf_free_maps(bp); kmem_zone_free(xfs_buf_zone, bp); } /* * Allocates all the pages for buffer in question and builds it's page list. */ STATIC int xfs_buf_allocate_memory( xfs_buf_t *bp, uint flags) { size_t size; size_t nbytes, offset; gfp_t gfp_mask = xb_to_gfp(flags); unsigned short page_count, i; xfs_off_t start, end; int error; /* * for buffers that are contained within a single page, just allocate * the memory from the heap - there's no need for the complexity of * page arrays to keep allocation down to order 0. */ size = BBTOB(bp->b_length); if (size < PAGE_SIZE) { bp->b_addr = kmem_alloc(size, KM_NOFS); if (!bp->b_addr) { /* low memory - use alloc_page loop instead */ goto use_alloc_page; } if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) != ((unsigned long)bp->b_addr & PAGE_MASK)) { /* b_addr spans two pages - use alloc_page instead */ kmem_free(bp->b_addr); bp->b_addr = NULL; goto use_alloc_page; } bp->b_offset = offset_in_page(bp->b_addr); bp->b_pages = bp->b_page_array; bp->b_pages[0] = virt_to_page(bp->b_addr); bp->b_page_count = 1; bp->b_flags |= _XBF_KMEM; return 0; } use_alloc_page: start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT; end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1) >> PAGE_SHIFT; page_count = end - start; error = _xfs_buf_get_pages(bp, page_count); if (unlikely(error)) return error; offset = bp->b_offset; bp->b_flags |= _XBF_PAGES; for (i = 0; i < bp->b_page_count; i++) { struct page *page; uint retries = 0; retry: page = alloc_page(gfp_mask); if (unlikely(page == NULL)) { if (flags & XBF_READ_AHEAD) { bp->b_page_count = i; error = -ENOMEM; goto out_free_pages; } /* * This could deadlock. * * But until all the XFS lowlevel code is revamped to * handle buffer allocation failures we can't do much. */ if (!(++retries % 100)) xfs_err(NULL, "%s(%u) possible memory allocation deadlock in %s (mode:0x%x)", current->comm, current->pid, __func__, gfp_mask); XFS_STATS_INC(bp->b_target->bt_mount, xb_page_retries); congestion_wait(BLK_RW_ASYNC, HZ/50); goto retry; } XFS_STATS_INC(bp->b_target->bt_mount, xb_page_found); nbytes = min_t(size_t, size, PAGE_SIZE - offset); size -= nbytes; bp->b_pages[i] = page; offset = 0; } return 0; out_free_pages: for (i = 0; i < bp->b_page_count; i++) __free_page(bp->b_pages[i]); return error; } /* * Map buffer into kernel address-space if necessary. */ STATIC int _xfs_buf_map_pages( xfs_buf_t *bp, uint flags) { ASSERT(bp->b_flags & _XBF_PAGES); if (bp->b_page_count == 1) { /* A single page buffer is always mappable */ bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset; } else if (flags & XBF_UNMAPPED) { bp->b_addr = NULL; } else { int retried = 0; unsigned noio_flag; /* * vm_map_ram() will allocate auxillary structures (e.g. * pagetables) with GFP_KERNEL, yet we are likely to be under * GFP_NOFS context here. Hence we need to tell memory reclaim * that we are in such a context via PF_MEMALLOC_NOIO to prevent * memory reclaim re-entering the filesystem here and * potentially deadlocking. */ noio_flag = memalloc_noio_save(); do { bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count, -1, PAGE_KERNEL); if (bp->b_addr) break; vm_unmap_aliases(); } while (retried++ <= 1); memalloc_noio_restore(noio_flag); if (!bp->b_addr) return -ENOMEM; bp->b_addr += bp->b_offset; } return 0; } /* * Finding and Reading Buffers */ /* * Look up, and creates if absent, a lockable buffer for * a given range of an inode. The buffer is returned * locked. No I/O is implied by this call. */ xfs_buf_t * _xfs_buf_find( struct xfs_buftarg *btp, struct xfs_buf_map *map, int nmaps, xfs_buf_flags_t flags, xfs_buf_t *new_bp) { struct xfs_perag *pag; struct rb_node **rbp; struct rb_node *parent; xfs_buf_t *bp; xfs_daddr_t blkno = map[0].bm_bn; xfs_daddr_t eofs; int numblks = 0; int i; for (i = 0; i < nmaps; i++) numblks += map[i].bm_len; /* Check for IOs smaller than the sector size / not sector aligned */ ASSERT(!(BBTOB(numblks) < btp->bt_meta_sectorsize)); ASSERT(!(BBTOB(blkno) & (xfs_off_t)btp->bt_meta_sectormask)); /* * Corrupted block numbers can get through to here, unfortunately, so we * have to check that the buffer falls within the filesystem bounds. */ eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks); if (blkno < 0 || blkno >= eofs) { /* * XXX (dgc): we should really be returning -EFSCORRUPTED here, * but none of the higher level infrastructure supports * returning a specific error on buffer lookup failures. */ xfs_alert(btp->bt_mount, "%s: Block out of range: block 0x%llx, EOFS 0x%llx ", __func__, blkno, eofs); WARN_ON(1); return NULL; } /* get tree root */ pag = xfs_perag_get(btp->bt_mount, xfs_daddr_to_agno(btp->bt_mount, blkno)); /* walk tree */ spin_lock(&pag->pag_buf_lock); rbp = &pag->pag_buf_tree.rb_node; parent = NULL; bp = NULL; while (*rbp) { parent = *rbp; bp = rb_entry(parent, struct xfs_buf, b_rbnode); if (blkno < bp->b_bn) rbp = &(*rbp)->rb_left; else if (blkno > bp->b_bn) rbp = &(*rbp)->rb_right; else { /* * found a block number match. If the range doesn't * match, the only way this is allowed is if the buffer * in the cache is stale and the transaction that made * it stale has not yet committed. i.e. we are * reallocating a busy extent. Skip this buffer and * continue searching to the right for an exact match. */ if (bp->b_length != numblks) { ASSERT(bp->b_flags & XBF_STALE); rbp = &(*rbp)->rb_right; continue; } atomic_inc(&bp->b_hold); goto found; } } /* No match found */ if (new_bp) { rb_link_node(&new_bp->b_rbnode, parent, rbp); rb_insert_color(&new_bp->b_rbnode, &pag->pag_buf_tree); /* the buffer keeps the perag reference until it is freed */ new_bp->b_pag = pag; spin_unlock(&pag->pag_buf_lock); } else { XFS_STATS_INC(btp->bt_mount, xb_miss_locked); spin_unlock(&pag->pag_buf_lock); xfs_perag_put(pag); } return new_bp; found: spin_unlock(&pag->pag_buf_lock); xfs_perag_put(pag); if (!xfs_buf_trylock(bp)) { if (flags & XBF_TRYLOCK) { xfs_buf_rele(bp); XFS_STATS_INC(btp->bt_mount, xb_busy_locked); return NULL; } xfs_buf_lock(bp); XFS_STATS_INC(btp->bt_mount, xb_get_locked_waited); } /* * if the buffer is stale, clear all the external state associated with * it. We need to keep flags such as how we allocated the buffer memory * intact here. */ if (bp->b_flags & XBF_STALE) { ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0); ASSERT(bp->b_iodone == NULL); bp->b_flags &= _XBF_KMEM | _XBF_PAGES; bp->b_ops = NULL; } trace_xfs_buf_find(bp, flags, _RET_IP_); XFS_STATS_INC(btp->bt_mount, xb_get_locked); return bp; } /* * Assembles a buffer covering the specified range. The code is optimised for * cache hits, as metadata intensive workloads will see 3 orders of magnitude * more hits than misses. */ struct xfs_buf * xfs_buf_get_map( struct xfs_buftarg *target, struct xfs_buf_map *map, int nmaps, xfs_buf_flags_t flags) { struct xfs_buf *bp; struct xfs_buf *new_bp; int error = 0; bp = _xfs_buf_find(target, map, nmaps, flags, NULL); if (likely(bp)) goto found; new_bp = _xfs_buf_alloc(target, map, nmaps, flags); if (unlikely(!new_bp)) return NULL; error = xfs_buf_allocate_memory(new_bp, flags); if (error) { xfs_buf_free(new_bp); return NULL; } bp = _xfs_buf_find(target, map, nmaps, flags, new_bp); if (!bp) { xfs_buf_free(new_bp); return NULL; } if (bp != new_bp) xfs_buf_free(new_bp); found: if (!bp->b_addr) { error = _xfs_buf_map_pages(bp, flags); if (unlikely(error)) { xfs_warn(target->bt_mount, "%s: failed to map pagesn", __func__); xfs_buf_relse(bp); return NULL; } } /* * Clear b_error if this is a lookup from a caller that doesn't expect * valid data to be found in the buffer. */ if (!(flags & XBF_READ)) xfs_buf_ioerror(bp, 0); XFS_STATS_INC(target->bt_mount, xb_get); trace_xfs_buf_get(bp, flags, _RET_IP_); return bp; } STATIC int _xfs_buf_read( xfs_buf_t *bp, xfs_buf_flags_t flags) { ASSERT(!(flags & XBF_WRITE)); ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL); bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD); bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD); if (flags & XBF_ASYNC) { xfs_buf_submit(bp); return 0; } return xfs_buf_submit_wait(bp); } xfs_buf_t * xfs_buf_read_map( struct xfs_buftarg *target, struct xfs_buf_map *map, int nmaps, xfs_buf_flags_t flags, const struct xfs_buf_ops *ops) { struct xfs_buf *bp; flags |= XBF_READ; bp = xfs_buf_get_map(target, map, nmaps, flags); if (bp) { trace_xfs_buf_read(bp, flags, _RET_IP_); if (!(bp->b_flags & XBF_DONE)) { XFS_STATS_INC(target->bt_mount, xb_get_read); bp->b_ops = ops; _xfs_buf_read(bp, flags); } else if (flags & XBF_ASYNC) { /* * Read ahead call which is already satisfied, * drop the buffer */ xfs_buf_relse(bp); return NULL; } else { /* We do not want read in the flags */ bp->b_flags &= ~XBF_READ; } } return bp; } /* * If we are not low on memory then do the readahead in a deadlock * safe manner. */ void xfs_buf_readahead_map( struct xfs_buftarg *target, struct xfs_buf_map *map, int nmaps, const struct xfs_buf_ops *ops) { if (bdi_read_congested(target->bt_bdi)) return; xfs_buf_read_map(target, map, nmaps, XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD, ops); } /* * Read an uncached buffer from disk. Allocates and returns a locked * buffer containing the disk contents or nothing. */ int xfs_buf_read_uncached( struct xfs_buftarg *target, xfs_daddr_t daddr, size_t numblks, int flags, struct xfs_buf **bpp, const struct xfs_buf_ops *ops) { struct xfs_buf *bp; *bpp = NULL; bp = xfs_buf_get_uncached(target, numblks, flags); if (!bp) return -ENOMEM; /* set up the buffer for a read IO */ ASSERT(bp->b_map_count == 1); bp->b_bn = XFS_BUF_DADDR_NULL; /* always null for uncached buffers */ bp->b_maps[0].bm_bn = daddr; bp->b_flags |= XBF_READ; bp->b_ops = ops; xfs_buf_submit_wait(bp); if (bp->b_error) { int error = bp->b_error; xfs_buf_relse(bp); return error; } *bpp = bp; return 0; } /* * Return a buffer allocated as an empty buffer and associated to external * memory via xfs_buf_associate_memory() back to it's empty state. */ void xfs_buf_set_empty( struct xfs_buf *bp, size_t numblks) { if (bp->b_pages) _xfs_buf_free_pages(bp); bp->b_pages = NULL; bp->b_page_count = 0; bp->b_addr = NULL; bp->b_length = numblks; bp->b_io_length = numblks; ASSERT(bp->b_map_count == 1); bp->b_bn = XFS_BUF_DADDR_NULL; bp->b_maps[0].bm_bn = XFS_BUF_DADDR_NULL; bp->b_maps[0].bm_len = bp->b_length; } static inline struct page * mem_to_page( void *addr) { if ((!is_vmalloc_addr(addr))) { return virt_to_page(addr); } else { return vmalloc_to_page(addr); } } int xfs_buf_associate_memory( xfs_buf_t *bp, void *mem, size_t len) { int rval; int i = 0; unsigned long pageaddr; unsigned long offset; size_t buflen; int page_count; pageaddr = (unsigned long)mem & PAGE_MASK; offset = (unsigned long)mem - pageaddr; buflen = PAGE_ALIGN(len + offset); page_count = buflen >> PAGE_SHIFT; /* Free any previous set of page pointers */ if (bp->b_pages) _xfs_buf_free_pages(bp); bp->b_pages = NULL; bp->b_addr = mem; rval = _xfs_buf_get_pages(bp, page_count); if (rval) return rval; bp->b_offset = offset; for (i = 0; i < bp->b_page_count; i++) { bp->b_pages[i] = mem_to_page((void *)pageaddr); pageaddr += PAGE_SIZE; } bp->b_io_length = BTOBB(len); bp->b_length = BTOBB(buflen); return 0; } xfs_buf_t * xfs_buf_get_uncached( struct xfs_buftarg *target, size_t numblks, int flags) { unsigned long page_count; int error, i; struct xfs_buf *bp; DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks); bp = _xfs_buf_alloc(target, &map, 1, 0); if (unlikely(bp == NULL)) goto fail; page_count = PAGE_ALIGN(numblks << BBSHIFT) >> PAGE_SHIFT; error = _xfs_buf_get_pages(bp, page_count); if (error) goto fail_free_buf; for (i = 0; i < page_count; i++) { bp->b_pages[i] = alloc_page(xb_to_gfp(flags)); if (!bp->b_pages[i]) goto fail_free_mem; } bp->b_flags |= _XBF_PAGES; error = _xfs_buf_map_pages(bp, 0); if (unlikely(error)) { xfs_warn(target->bt_mount, "%s: failed to map pages", __func__); goto fail_free_mem; } trace_xfs_buf_get_uncached(bp, _RET_IP_); return bp; fail_free_mem: while (--i >= 0) __free_page(bp->b_pages[i]); _xfs_buf_free_pages(bp); fail_free_buf: xfs_buf_free_maps(bp); kmem_zone_free(xfs_buf_zone, bp); fail: return NULL; } /* * Increment reference count on buffer, to hold the buffer concurrently * with another thread which may release (free) the buffer asynchronously. * Must hold the buffer already to call this function. */ void xfs_buf_hold( xfs_buf_t *bp) { trace_xfs_buf_hold(bp, _RET_IP_); atomic_inc(&bp->b_hold); } /* * Releases a hold on the specified buffer. If the * the hold count is 1, calls xfs_buf_free. */ void xfs_buf_rele( xfs_buf_t *bp) { struct xfs_perag *pag = bp->b_pag; trace_xfs_buf_rele(bp, _RET_IP_); if (!pag) { ASSERT(list_empty(&bp->b_lru)); ASSERT(RB_EMPTY_NODE(&bp->b_rbnode)); if (atomic_dec_and_test(&bp->b_hold)) xfs_buf_free(bp); return; } ASSERT(!RB_EMPTY_NODE(&bp->b_rbnode)); ASSERT(atomic_read(&bp->b_hold) > 0); if (atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock)) { spin_lock(&bp->b_lock); if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) { /* * If the buffer is added to the LRU take a new * reference to the buffer for the LRU and clear the * (now stale) dispose list state flag */ if (list_lru_add(&bp->b_target->bt_lru, &bp->b_lru)) { bp->b_state &= ~XFS_BSTATE_DISPOSE; atomic_inc(&bp->b_hold); } spin_unlock(&bp->b_lock); spin_unlock(&pag->pag_buf_lock); } else { /* * most of the time buffers will already be removed from * the LRU, so optimise that case by checking for the * XFS_BSTATE_DISPOSE flag indicating the last list the * buffer was on was the disposal list */ if (!(bp->b_state & XFS_BSTATE_DISPOSE)) { list_lru_del(&bp->b_target->bt_lru, &bp->b_lru); } else { ASSERT(list_empty(&bp->b_lru)); } spin_unlock(&bp->b_lock); ASSERT(!(bp->b_flags & _XBF_DELWRI_Q)); rb_erase(&bp->b_rbnode, &pag->pag_buf_tree); spin_unlock(&pag->pag_buf_lock); xfs_perag_put(pag); xfs_buf_free(bp); } } } /* * Lock a buffer object, if it is not already locked. * * If we come across a stale, pinned, locked buffer, we know that we are * being asked to lock a buffer that has been reallocated. Because it is * pinned, we know that the log has not been pushed to disk and hence it * will still be locked. Rather than continuing to have trylock attempts * fail until someone else pushes the log, push it ourselves before * returning. This means that the xfsaild will not get stuck trying * to push on stale inode buffers. */ int xfs_buf_trylock( struct xfs_buf *bp) { int locked; locked = down_trylock(&bp->b_sema) == 0; if (locked) { XB_SET_OWNER(bp); trace_xfs_buf_trylock(bp, _RET_IP_); } else { trace_xfs_buf_trylock_fail(bp, _RET_IP_); } return locked; } /* * Lock a buffer object. * * If we come across a stale, pinned, locked buffer, we know that we * are being asked to lock a buffer that has been reallocated. Because * it is pinned, we know that the log has not been pushed to disk and * hence it will still be locked. Rather than sleeping until someone * else pushes the log, push it ourselves before trying to get the lock. */ void xfs_buf_lock( struct xfs_buf *bp) { trace_xfs_buf_lock(bp, _RET_IP_); if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE)) xfs_log_force(bp->b_target->bt_mount, 0); down(&bp->b_sema); XB_SET_OWNER(bp); trace_xfs_buf_lock_done(bp, _RET_IP_); } void xfs_buf_unlock( struct xfs_buf *bp) { XB_CLEAR_OWNER(bp); up(&bp->b_sema); trace_xfs_buf_unlock(bp, _RET_IP_); } STATIC void xfs_buf_wait_unpin( xfs_buf_t *bp) { DECLARE_WAITQUEUE (wait, current); if (atomic_read(&bp->b_pin_count) == 0) return; add_wait_queue(&bp->b_waiters, &wait); for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (atomic_read(&bp->b_pin_count) == 0) break; io_schedule(); } remove_wait_queue(&bp->b_waiters, &wait); set_current_state(TASK_RUNNING); } /* * Buffer Utility Routines */ void xfs_buf_ioend( struct xfs_buf *bp) { bool read = bp->b_flags & XBF_READ; trace_xfs_buf_iodone(bp, _RET_IP_); bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD); /* * Pull in IO completion errors now. We are guaranteed to be running * single threaded, so we don't need the lock to read b_io_error. */ if (!bp->b_error && bp->b_io_error) xfs_buf_ioerror(bp, bp->b_io_error); /* Only validate buffers that were read without errors */ if (read && !bp->b_error && bp->b_ops) { ASSERT(!bp->b_iodone); bp->b_ops->verify_read(bp); } if (!bp->b_error) bp->b_flags |= XBF_DONE; if (bp->b_iodone) (*(bp->b_iodone))(bp); else if (bp->b_flags & XBF_ASYNC) xfs_buf_relse(bp); else complete(&bp->b_iowait); } static void xfs_buf_ioend_work( struct work_struct *work) { struct xfs_buf *bp = container_of(work, xfs_buf_t, b_ioend_work); xfs_buf_ioend(bp); } static void xfs_buf_ioend_async( struct xfs_buf *bp) { INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work); queue_work(bp->b_ioend_wq, &bp->b_ioend_work); } void xfs_buf_ioerror( xfs_buf_t *bp, int error) { ASSERT(error <= 0 && error >= -1000); bp->b_error = error; trace_xfs_buf_ioerror(bp, error, _RET_IP_); } void xfs_buf_ioerror_alert( struct xfs_buf *bp, const char *func) { xfs_alert(bp->b_target->bt_mount, "metadata I/O error: block 0x%llx (\"%s\") error %d numblks %d", (__uint64_t)XFS_BUF_ADDR(bp), func, -bp->b_error, bp->b_length); } int xfs_bwrite( struct xfs_buf *bp) { int error; ASSERT(xfs_buf_islocked(bp)); bp->b_flags |= XBF_WRITE; bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q | XBF_WRITE_FAIL | XBF_DONE); error = xfs_buf_submit_wait(bp); if (error) { xfs_force_shutdown(bp->b_target->bt_mount, SHUTDOWN_META_IO_ERROR); } return error; } static void xfs_buf_bio_end_io( struct bio *bio) { struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private; /* * don't overwrite existing errors - otherwise we can lose errors on * buffers that require multiple bios to complete. */ if (bio->bi_error) cmpxchg(&bp->b_io_error, 0, bio->bi_error); if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ)) invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp)); if (atomic_dec_and_test(&bp->b_io_remaining) == 1) xfs_buf_ioend_async(bp); bio_put(bio); } static void xfs_buf_ioapply_map( struct xfs_buf *bp, int map, int *buf_offset, int *count, int rw) { int page_index; int total_nr_pages = bp->b_page_count; int nr_pages; struct bio *bio; sector_t sector = bp->b_maps[map].bm_bn; int size; int offset; total_nr_pages = bp->b_page_count; /* skip the pages in the buffer before the start offset */ page_index = 0; offset = *buf_offset; while (offset >= PAGE_SIZE) { page_index++; offset -= PAGE_SIZE; } /* * Limit the IO size to the length of the current vector, and update the * remaining IO count for the next time around. */ size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count); *count -= size; *buf_offset += size; next_chunk: atomic_inc(&bp->b_io_remaining); nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT); if (nr_pages > total_nr_pages) nr_pages = total_nr_pages; bio = bio_alloc(GFP_NOIO, nr_pages); bio->bi_bdev = bp->b_target->bt_bdev; bio->bi_iter.bi_sector = sector; bio->bi_end_io = xfs_buf_bio_end_io; bio->bi_private = bp; for (; size && nr_pages; nr_pages--, page_index++) { int rbytes, nbytes = PAGE_SIZE - offset; if (nbytes > size) nbytes = size; rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes, offset); if (rbytes < nbytes) break; offset = 0; sector += BTOBB(nbytes); size -= nbytes; total_nr_pages--; } if (likely(bio->bi_iter.bi_size)) { if (xfs_buf_is_vmapped(bp)) { flush_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp)); } submit_bio(rw, bio); if (size) goto next_chunk; } else { /* * This is guaranteed not to be the last io reference count * because the caller (xfs_buf_submit) holds a count itself. */ atomic_dec(&bp->b_io_remaining); xfs_buf_ioerror(bp, -EIO); bio_put(bio); } } STATIC void _xfs_buf_ioapply( struct xfs_buf *bp) { struct blk_plug plug; int rw; int offset; int size; int i; /* * Make sure we capture only current IO errors rather than stale errors * left over from previous use of the buffer (e.g. failed readahead). */ bp->b_error = 0; /* * Initialize the I/O completion workqueue if we haven't yet or the * submitter has not opted to specify a custom one. */ if (!bp->b_ioend_wq) bp->b_ioend_wq = bp->b_target->bt_mount->m_buf_workqueue; if (bp->b_flags & XBF_WRITE) { if (bp->b_flags & XBF_SYNCIO) rw = WRITE_SYNC; else rw = WRITE; if (bp->b_flags & XBF_FUA) rw |= REQ_FUA; if (bp->b_flags & XBF_FLUSH) rw |= REQ_FLUSH; /* * Run the write verifier callback function if it exists. If * this function fails it will mark the buffer with an error and * the IO should not be dispatched. */ if (bp->b_ops) { bp->b_ops->verify_write(bp); if (bp->b_error) { xfs_force_shutdown(bp->b_target->bt_mount, SHUTDOWN_CORRUPT_INCORE); return; } } else if (bp->b_bn != XFS_BUF_DADDR_NULL) { struct xfs_mount *mp = bp->b_target->bt_mount; /* * non-crc filesystems don't attach verifiers during * log recovery, so don't warn for such filesystems. */ if (xfs_sb_version_hascrc(&mp->m_sb)) { xfs_warn(mp, "%s: no ops on block 0x%llx/0x%x", __func__, bp->b_bn, bp->b_length); xfs_hex_dump(bp->b_addr, 64); dump_stack(); } } } else if (bp->b_flags & XBF_READ_AHEAD) { rw = READA; } else { rw = READ; } /* we only use the buffer cache for meta-data */ rw |= REQ_META; /* * Walk all the vectors issuing IO on them. Set up the initial offset * into the buffer and the desired IO size before we start - * _xfs_buf_ioapply_vec() will modify them appropriately for each * subsequent call. */ offset = bp->b_offset; size = BBTOB(bp->b_io_length); blk_start_plug(&plug); for (i = 0; i < bp->b_map_count; i++) { xfs_buf_ioapply_map(bp, i, &offset, &size, rw); if (bp->b_error) break; if (size <= 0) break; /* all done */ } blk_finish_plug(&plug); } /* * Asynchronous IO submission path. This transfers the buffer lock ownership and * the current reference to the IO. It is not safe to reference the buffer after * a call to this function unless the caller holds an additional reference * itself. */ void xfs_buf_submit( struct xfs_buf *bp) { trace_xfs_buf_submit(bp, _RET_IP_); ASSERT(!(bp->b_flags & _XBF_DELWRI_Q)); ASSERT(bp->b_flags & XBF_ASYNC); /* on shutdown we stale and complete the buffer immediately */ if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) { xfs_buf_ioerror(bp, -EIO); bp->b_flags &= ~XBF_DONE; xfs_buf_stale(bp); xfs_buf_ioend(bp); return; } if (bp->b_flags & XBF_WRITE) xfs_buf_wait_unpin(bp); /* clear the internal error state to avoid spurious errors */ bp->b_io_error = 0; /* * The caller's reference is released during I/O completion. * This occurs some time after the last b_io_remaining reference is * released, so after we drop our Io reference we have to have some * other reference to ensure the buffer doesn't go away from underneath * us. Take a direct reference to ensure we have safe access to the * buffer until we are finished with it. */ xfs_buf_hold(bp); /* * Set the count to 1 initially, this will stop an I/O completion * callout which happens before we have started all the I/O from calling * xfs_buf_ioend too early. */ atomic_set(&bp->b_io_remaining, 1); _xfs_buf_ioapply(bp); /* * If _xfs_buf_ioapply failed, we can get back here with only the IO * reference we took above. If we drop it to zero, run completion so * that we don't return to the caller with completion still pending. */ if (atomic_dec_and_test(&bp->b_io_remaining) == 1) { if (bp->b_error) xfs_buf_ioend(bp); else xfs_buf_ioend_async(bp); } xfs_buf_rele(bp); /* Note: it is not safe to reference bp now we've dropped our ref */ } /* * Synchronous buffer IO submission path, read or write. */ int xfs_buf_submit_wait( struct xfs_buf *bp) { int error; trace_xfs_buf_submit_wait(bp, _RET_IP_); ASSERT(!(bp->b_flags & (_XBF_DELWRI_Q | XBF_ASYNC))); if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) { xfs_buf_ioerror(bp, -EIO); xfs_buf_stale(bp); bp->b_flags &= ~XBF_DONE; return -EIO; } if (bp->b_flags & XBF_WRITE) xfs_buf_wait_unpin(bp); /* clear the internal error state to avoid spurious errors */ bp->b_io_error = 0; /* * For synchronous IO, the IO does not inherit the submitters reference * count, nor the buffer lock. Hence we cannot release the reference we * are about to take until we've waited for all IO completion to occur, * including any xfs_buf_ioend_async() work that may be pending. */ xfs_buf_hold(bp); /* * Set the count to 1 initially, this will stop an I/O completion * callout which happens before we have started all the I/O from calling * xfs_buf_ioend too early. */ atomic_set(&bp->b_io_remaining, 1); _xfs_buf_ioapply(bp); /* * make sure we run completion synchronously if it raced with us and is * already complete. */ if (atomic_dec_and_test(&bp->b_io_remaining) == 1) xfs_buf_ioend(bp); /* wait for completion before gathering the error from the buffer */ trace_xfs_buf_iowait(bp, _RET_IP_); wait_for_completion(&bp->b_iowait); trace_xfs_buf_iowait_done(bp, _RET_IP_); error = bp->b_error; /* * all done now, we can release the hold that keeps the buffer * referenced for the entire IO. */ xfs_buf_rele(bp); return error; } void * xfs_buf_offset( struct xfs_buf *bp, size_t offset) { struct page *page; if (bp->b_addr) return bp->b_addr + offset; offset += bp->b_offset; page = bp->b_pages[offset >> PAGE_SHIFT]; return page_address(page) + (offset & (PAGE_SIZE-1)); } /* * Move data into or out of a buffer. */ void xfs_buf_iomove( xfs_buf_t *bp, /* buffer to process */ size_t boff, /* starting buffer offset */ size_t bsize, /* length to copy */ void *data, /* data address */ xfs_buf_rw_t mode) /* read/write/zero flag */ { size_t bend; bend = boff + bsize; while (boff < bend) { struct page *page; int page_index, page_offset, csize; page_index = (boff + bp->b_offset) >> PAGE_SHIFT; page_offset = (boff + bp->b_offset) & ~PAGE_MASK; page = bp->b_pages[page_index]; csize = min_t(size_t, PAGE_SIZE - page_offset, BBTOB(bp->b_io_length) - boff); ASSERT((csize + page_offset) <= PAGE_SIZE); switch (mode) { case XBRW_ZERO: memset(page_address(page) + page_offset, 0, csize); break; case XBRW_READ: memcpy(data, page_address(page) + page_offset, csize); break; case XBRW_WRITE: memcpy(page_address(page) + page_offset, data, csize); } boff += csize; data += csize; } } /* * Handling of buffer targets (buftargs). */ /* * Wait for any bufs with callbacks that have been submitted but have not yet * returned. These buffers will have an elevated hold count, so wait on those * while freeing all the buffers only held by the LRU. */ static enum lru_status xfs_buftarg_wait_rele( struct list_head *item, struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) { struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru); struct list_head *dispose = arg; if (atomic_read(&bp->b_hold) > 1) { /* need to wait, so skip it this pass */ trace_xfs_buf_wait_buftarg(bp, _RET_IP_); return LRU_SKIP; } if (!spin_trylock(&bp->b_lock)) return LRU_SKIP; /* * clear the LRU reference count so the buffer doesn't get * ignored in xfs_buf_rele(). */ atomic_set(&bp->b_lru_ref, 0); bp->b_state |= XFS_BSTATE_DISPOSE; list_lru_isolate_move(lru, item, dispose); spin_unlock(&bp->b_lock); return LRU_REMOVED; } void xfs_wait_buftarg( struct xfs_buftarg *btp) { LIST_HEAD(dispose); int loop = 0; /* * We need to flush the buffer workqueue to ensure that all IO * completion processing is 100% done. Just waiting on buffer locks is * not sufficient for async IO as the reference count held over IO is * not released until after the buffer lock is dropped. Hence we need to * ensure here that all reference counts have been dropped before we * start walking the LRU list. */ drain_workqueue(btp->bt_mount->m_buf_workqueue); /* loop until there is nothing left on the lru list. */ while (list_lru_count(&btp->bt_lru)) { list_lru_walk(&btp->bt_lru, xfs_buftarg_wait_rele, &dispose, LONG_MAX); while (!list_empty(&dispose)) { struct xfs_buf *bp; bp = list_first_entry(&dispose, struct xfs_buf, b_lru); list_del_init(&bp->b_lru); if (bp->b_flags & XBF_WRITE_FAIL) { xfs_alert(btp->bt_mount, "Corruption Alert: Buffer at block 0x%llx had permanent write failures!", (long long)bp->b_bn); xfs_alert(btp->bt_mount, "Please run xfs_repair to determine the extent of the problem."); } xfs_buf_rele(bp); } if (loop++ != 0) delay(100); } } static enum lru_status xfs_buftarg_isolate( struct list_head *item, struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) { struct xfs_buf *bp = container_of(item, struct xfs_buf, b_lru); struct list_head *dispose = arg; /* * we are inverting the lru lock/bp->b_lock here, so use a trylock. * If we fail to get the lock, just skip it. */ if (!spin_trylock(&bp->b_lock)) return LRU_SKIP; /* * Decrement the b_lru_ref count unless the value is already * zero. If the value is already zero, we need to reclaim the * buffer, otherwise it gets another trip through the LRU. */ if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) { spin_unlock(&bp->b_lock); return LRU_ROTATE; } bp->b_state |= XFS_BSTATE_DISPOSE; list_lru_isolate_move(lru, item, dispose); spin_unlock(&bp->b_lock); return LRU_REMOVED; } static unsigned long xfs_buftarg_shrink_scan( struct shrinker *shrink, struct shrink_control *sc) { struct xfs_buftarg *btp = container_of(shrink, struct xfs_buftarg, bt_shrinker); LIST_HEAD(dispose); unsigned long freed; freed = list_lru_shrink_walk(&btp->bt_lru, sc, xfs_buftarg_isolate, &dispose); while (!list_empty(&dispose)) { struct xfs_buf *bp; bp = list_first_entry(&dispose, struct xfs_buf, b_lru); list_del_init(&bp->b_lru); xfs_buf_rele(bp); } return freed; } static unsigned long xfs_buftarg_shrink_count( struct shrinker *shrink, struct shrink_control *sc) { struct xfs_buftarg *btp = container_of(shrink, struct xfs_buftarg, bt_shrinker); return list_lru_shrink_count(&btp->bt_lru, sc); } void xfs_free_buftarg( struct xfs_mount *mp, struct xfs_buftarg *btp) { unregister_shrinker(&btp->bt_shrinker); list_lru_destroy(&btp->bt_lru); if (mp->m_flags & XFS_MOUNT_BARRIER) xfs_blkdev_issue_flush(btp); kmem_free(btp); } int xfs_setsize_buftarg( xfs_buftarg_t *btp, unsigned int sectorsize) { /* Set up metadata sector size info */ btp->bt_meta_sectorsize = sectorsize; btp->bt_meta_sectormask = sectorsize - 1; if (set_blocksize(btp->bt_bdev, sectorsize)) { xfs_warn(btp->bt_mount, "Cannot set_blocksize to %u on device %pg", sectorsize, btp->bt_bdev); return -EINVAL; } /* Set up device logical sector size mask */ btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev); btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1; return 0; } /* * When allocating the initial buffer target we have not yet * read in the superblock, so don't know what sized sectors * are being used at this early stage. Play safe. */ STATIC int xfs_setsize_buftarg_early( xfs_buftarg_t *btp, struct block_device *bdev) { return xfs_setsize_buftarg(btp, bdev_logical_block_size(bdev)); } xfs_buftarg_t * xfs_alloc_buftarg( struct xfs_mount *mp, struct block_device *bdev) { xfs_buftarg_t *btp; btp = kmem_zalloc(sizeof(*btp), KM_SLEEP | KM_NOFS); btp->bt_mount = mp; btp->bt_dev = bdev->bd_dev; btp->bt_bdev = bdev; btp->bt_bdi = blk_get_backing_dev_info(bdev); if (xfs_setsize_buftarg_early(btp, bdev)) goto error; if (list_lru_init(&btp->bt_lru)) goto error; btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count; btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan; btp->bt_shrinker.seeks = DEFAULT_SEEKS; btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE; register_shrinker(&btp->bt_shrinker); return btp; error: kmem_free(btp); return NULL; } /* * Add a buffer to the delayed write list. * * This queues a buffer for writeout if it hasn't already been. Note that * neither this routine nor the buffer list submission functions perform * any internal synchronization. It is expected that the lists are thread-local * to the callers. * * Returns true if we queued up the buffer, or false if it already had * been on the buffer list. */ bool xfs_buf_delwri_queue( struct xfs_buf *bp, struct list_head *list) { ASSERT(xfs_buf_islocked(bp)); ASSERT(!(bp->b_flags & XBF_READ)); /* * If the buffer is already marked delwri it already is queued up * by someone else for imediate writeout. Just ignore it in that * case. */ if (bp->b_flags & _XBF_DELWRI_Q) { trace_xfs_buf_delwri_queued(bp, _RET_IP_); return false; } trace_xfs_buf_delwri_queue(bp, _RET_IP_); /* * If a buffer gets written out synchronously or marked stale while it * is on a delwri list we lazily remove it. To do this, the other party * clears the _XBF_DELWRI_Q flag but otherwise leaves the buffer alone. * It remains referenced and on the list. In a rare corner case it * might get readded to a delwri list after the synchronous writeout, in * which case we need just need to re-add the flag here. */ bp->b_flags |= _XBF_DELWRI_Q; if (list_empty(&bp->b_list)) { atomic_inc(&bp->b_hold); list_add_tail(&bp->b_list, list); } return true; } /* * Compare function is more complex than it needs to be because * the return value is only 32 bits and we are doing comparisons * on 64 bit values */ static int xfs_buf_cmp( void *priv, struct list_head *a, struct list_head *b) { struct xfs_buf *ap = container_of(a, struct xfs_buf, b_list); struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list); xfs_daddr_t diff; diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn; if (diff < 0) return -1; if (diff > 0) return 1; return 0; } static int __xfs_buf_delwri_submit( struct list_head *buffer_list, struct list_head *io_list, bool wait) { struct blk_plug plug; struct xfs_buf *bp, *n; int pinned = 0; list_for_each_entry_safe(bp, n, buffer_list, b_list) { if (!wait) { if (xfs_buf_ispinned(bp)) { pinned++; continue; } if (!xfs_buf_trylock(bp)) continue; } else { xfs_buf_lock(bp); } /* * Someone else might have written the buffer synchronously or * marked it stale in the meantime. In that case only the * _XBF_DELWRI_Q flag got cleared, and we have to drop the * reference and remove it from the list here. */ if (!(bp->b_flags & _XBF_DELWRI_Q)) { list_del_init(&bp->b_list); xfs_buf_relse(bp); continue; } list_move_tail(&bp->b_list, io_list); trace_xfs_buf_delwri_split(bp, _RET_IP_); } list_sort(NULL, io_list, xfs_buf_cmp); blk_start_plug(&plug); list_for_each_entry_safe(bp, n, io_list, b_list) { bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_ASYNC | XBF_WRITE_FAIL); bp->b_flags |= XBF_WRITE | XBF_ASYNC; /* * we do all Io submission async. This means if we need to wait * for IO completion we need to take an extra reference so the * buffer is still valid on the other side. */ if (wait) xfs_buf_hold(bp); else list_del_init(&bp->b_list); xfs_buf_submit(bp); } blk_finish_plug(&plug); return pinned; } /* * Write out a buffer list asynchronously. * * This will take the @buffer_list, write all non-locked and non-pinned buffers * out and not wait for I/O completion on any of the buffers. This interface * is only safely useable for callers that can track I/O completion by higher * level means, e.g. AIL pushing as the @buffer_list is consumed in this * function. */ int xfs_buf_delwri_submit_nowait( struct list_head *buffer_list) { LIST_HEAD (io_list); return __xfs_buf_delwri_submit(buffer_list, &io_list, false); } /* * Write out a buffer list synchronously. * * This will take the @buffer_list, write all buffers out and wait for I/O * completion on all of the buffers. @buffer_list is consumed by the function, * so callers must have some other way of tracking buffers if they require such * functionality. */ int xfs_buf_delwri_submit( struct list_head *buffer_list) { LIST_HEAD (io_list); int error = 0, error2; struct xfs_buf *bp; __xfs_buf_delwri_submit(buffer_list, &io_list, true); /* Wait for IO to complete. */ while (!list_empty(&io_list)) { bp = list_first_entry(&io_list, struct xfs_buf, b_list); list_del_init(&bp->b_list); /* locking the buffer will wait for async IO completion. */ xfs_buf_lock(bp); error2 = bp->b_error; xfs_buf_relse(bp); if (!error) error = error2; } return error; } int __init xfs_buf_init(void) { xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf", KM_ZONE_HWALIGN, NULL); if (!xfs_buf_zone) goto out; return 0; out: return -ENOMEM; } void xfs_buf_terminate(void) { kmem_zone_destroy(xfs_buf_zone); }