| /* |
| * 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 <linux/stddef.h> |
| #include <linux/errno.h> |
| #include <linux/gfp.h> |
| #include <linux/pagemap.h> |
| #include <linux/init.h> |
| #include <linux/vmalloc.h> |
| #include <linux/bio.h> |
| #include <linux/sysctl.h> |
| #include <linux/proc_fs.h> |
| #include <linux/workqueue.h> |
| #include <linux/percpu.h> |
| #include <linux/blkdev.h> |
| #include <linux/hash.h> |
| #include <linux/kthread.h> |
| #include <linux/migrate.h> |
| #include <linux/backing-dev.h> |
| #include <linux/freezer.h> |
| #include <linux/sched/mm.h> |
| |
| #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; |
| } |
| |
| /* |
| * Bump the I/O in flight count on the buftarg if we haven't yet done so for |
| * this buffer. The count is incremented once per buffer (per hold cycle) |
| * because the corresponding decrement is deferred to buffer release. Buffers |
| * can undergo I/O multiple times in a hold-release cycle and per buffer I/O |
| * tracking adds unnecessary overhead. This is used for sychronization purposes |
| * with unmount (see xfs_wait_buftarg()), so all we really need is a count of |
| * in-flight buffers. |
| * |
| * Buffers that are never released (e.g., superblock, iclog buffers) must set |
| * the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count |
| * never reaches zero and unmount hangs indefinitely. |
| */ |
| static inline void |
| xfs_buf_ioacct_inc( |
| struct xfs_buf *bp) |
| { |
| if (bp->b_flags & XBF_NO_IOACCT) |
| return; |
| |
| ASSERT(bp->b_flags & XBF_ASYNC); |
| spin_lock(&bp->b_lock); |
| if (!(bp->b_state & XFS_BSTATE_IN_FLIGHT)) { |
| bp->b_state |= XFS_BSTATE_IN_FLIGHT; |
| percpu_counter_inc(&bp->b_target->bt_io_count); |
| } |
| spin_unlock(&bp->b_lock); |
| } |
| |
| /* |
| * Clear the in-flight state on a buffer about to be released to the LRU or |
| * freed and unaccount from the buftarg. |
| */ |
| static inline void |
| __xfs_buf_ioacct_dec( |
| struct xfs_buf *bp) |
| { |
| lockdep_assert_held(&bp->b_lock); |
| |
| if (bp->b_state & XFS_BSTATE_IN_FLIGHT) { |
| bp->b_state &= ~XFS_BSTATE_IN_FLIGHT; |
| percpu_counter_dec(&bp->b_target->bt_io_count); |
| } |
| } |
| |
| static inline void |
| xfs_buf_ioacct_dec( |
| struct xfs_buf *bp) |
| { |
| spin_lock(&bp->b_lock); |
| __xfs_buf_ioacct_dec(bp); |
| spin_unlock(&bp->b_lock); |
| } |
| |
| /* |
| * 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; |
| |
| /* |
| * Once the buffer is marked stale and unlocked, a subsequent lookup |
| * could reset b_flags. There is no guarantee that the buffer is |
| * unaccounted (released to LRU) before that occurs. Drop in-flight |
| * status now to preserve accounting consistency. |
| */ |
| spin_lock(&bp->b_lock); |
| __xfs_buf_ioacct_dec(bp); |
| |
| 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); |
| 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]); |
| bp->b_flags &= ~_XBF_PAGES; |
| 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 nofs_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_NOFS to prevent |
| * memory reclaim re-entering the filesystem here and |
| * potentially deadlocking. |
| */ |
| nofs_flag = memalloc_nofs_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_nofs_restore(nofs_flag); |
| |
| if (!bp->b_addr) |
| return -ENOMEM; |
| bp->b_addr += bp->b_offset; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Finding and Reading Buffers |
| */ |
| static int |
| _xfs_buf_obj_cmp( |
| struct rhashtable_compare_arg *arg, |
| const void *obj) |
| { |
| const struct xfs_buf_map *map = arg->key; |
| const struct xfs_buf *bp = obj; |
| |
| /* |
| * The key hashing in the lookup path depends on the key being the |
| * first element of the compare_arg, make sure to assert this. |
| */ |
| BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0); |
| |
| if (bp->b_bn != map->bm_bn) |
| return 1; |
| |
| if (unlikely(bp->b_length != map->bm_len)) { |
| /* |
| * 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 for an exact match. |
| */ |
| ASSERT(bp->b_flags & XBF_STALE); |
| return 1; |
| } |
| return 0; |
| } |
| |
| static const struct rhashtable_params xfs_buf_hash_params = { |
| .min_size = 32, /* empty AGs have minimal footprint */ |
| .nelem_hint = 16, |
| .key_len = sizeof(xfs_daddr_t), |
| .key_offset = offsetof(struct xfs_buf, b_bn), |
| .head_offset = offsetof(struct xfs_buf, b_rhash_head), |
| .automatic_shrinking = true, |
| .obj_cmpfn = _xfs_buf_obj_cmp, |
| }; |
| |
| int |
| xfs_buf_hash_init( |
| struct xfs_perag *pag) |
| { |
| spin_lock_init(&pag->pag_buf_lock); |
| return rhashtable_init(&pag->pag_buf_hash, &xfs_buf_hash_params); |
| } |
| |
| void |
| xfs_buf_hash_destroy( |
| struct xfs_perag *pag) |
| { |
| rhashtable_destroy(&pag->pag_buf_hash); |
| } |
| |
| /* |
| * 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; |
| xfs_buf_t *bp; |
| struct xfs_buf_map cmap = { .bm_bn = map[0].bm_bn }; |
| xfs_daddr_t eofs; |
| int i; |
| |
| for (i = 0; i < nmaps; i++) |
| cmap.bm_len += map[i].bm_len; |
| |
| /* Check for IOs smaller than the sector size / not sector aligned */ |
| ASSERT(!(BBTOB(cmap.bm_len) < btp->bt_meta_sectorsize)); |
| ASSERT(!(BBTOB(cmap.bm_bn) & (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 (cmap.bm_bn < 0 || cmap.bm_bn >= 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__, cmap.bm_bn, eofs); |
| WARN_ON(1); |
| return NULL; |
| } |
| |
| pag = xfs_perag_get(btp->bt_mount, |
| xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn)); |
| |
| spin_lock(&pag->pag_buf_lock); |
| bp = rhashtable_lookup_fast(&pag->pag_buf_hash, &cmap, |
| xfs_buf_hash_params); |
| if (bp) { |
| atomic_inc(&bp->b_hold); |
| goto found; |
| } |
| |
| /* No match found */ |
| if (new_bp) { |
| /* the buffer keeps the perag reference until it is freed */ |
| new_bp->b_pag = pag; |
| rhashtable_insert_fast(&pag->pag_buf_hash, |
| &new_bp->b_rhash_head, |
| xfs_buf_hash_params); |
| 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_bdev->bd_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); |
| |
| /* flags might contain irrelevant bits, pass only what we care about */ |
| bp = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT); |
| 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); |
| } |
| |
| /* |
| * Release a hold on the specified buffer. If the hold count is 1, the buffer is |
| * placed on LRU or freed (depending on b_lru_ref). |
| */ |
| void |
| xfs_buf_rele( |
| xfs_buf_t *bp) |
| { |
| struct xfs_perag *pag = bp->b_pag; |
| bool release; |
| bool freebuf = false; |
| |
| trace_xfs_buf_rele(bp, _RET_IP_); |
| |
| if (!pag) { |
| ASSERT(list_empty(&bp->b_lru)); |
| if (atomic_dec_and_test(&bp->b_hold)) { |
| xfs_buf_ioacct_dec(bp); |
| xfs_buf_free(bp); |
| } |
| return; |
| } |
| |
| ASSERT(atomic_read(&bp->b_hold) > 0); |
| |
| release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock); |
| spin_lock(&bp->b_lock); |
| if (!release) { |
| /* |
| * Drop the in-flight state if the buffer is already on the LRU |
| * and it holds the only reference. This is racy because we |
| * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT |
| * ensures the decrement occurs only once per-buf. |
| */ |
| if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru)) |
| __xfs_buf_ioacct_dec(bp); |
| goto out_unlock; |
| } |
| |
| /* the last reference has been dropped ... */ |
| __xfs_buf_ioacct_dec(bp); |
| 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(&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)); |
| } |
| |
| ASSERT(!(bp->b_flags & _XBF_DELWRI_Q)); |
| rhashtable_remove_fast(&pag->pag_buf_hash, &bp->b_rhash_head, |
| xfs_buf_hash_params); |
| spin_unlock(&pag->pag_buf_lock); |
| xfs_perag_put(pag); |
| freebuf = true; |
| } |
| |
| out_unlock: |
| spin_unlock(&bp->b_lock); |
| |
| if (freebuf) |
| 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) |
| { |
| ASSERT(xfs_buf_islocked(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 op, |
| int op_flags) |
| { |
| 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 = min(total_nr_pages, BIO_MAX_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; |
| bio_set_op_attrs(bio, op, op_flags); |
| |
| 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(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 op; |
| int op_flags = 0; |
| 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) { |
| op = REQ_OP_WRITE; |
| if (bp->b_flags & XBF_SYNCIO) |
| op_flags = REQ_SYNC; |
| if (bp->b_flags & XBF_FUA) |
| op_flags |= REQ_FUA; |
| if (bp->b_flags & XBF_FLUSH) |
| op_flags |= REQ_PREFLUSH; |
| |
| /* |
| * 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) { |
| op = REQ_OP_READ; |
| op_flags = REQ_RAHEAD; |
| } else { |
| op = REQ_OP_READ; |
| } |
| |
| /* we only use the buffer cache for meta-data */ |
| op_flags |= 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, op, op_flags); |
| 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_ioacct_inc(bp); |
| _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; |
| |
| /* |
| * First wait on the buftarg I/O count for all in-flight buffers to be |
| * released. This is critical as new buffers do not make the LRU until |
| * they are released. |
| * |
| * Next, flush the buffer workqueue to ensure all completion processing |
| * has finished. 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. |
| */ |
| while (percpu_counter_sum(&btp->bt_io_count)) |
| delay(100); |
| flush_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); |
| ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0); |
| percpu_counter_destroy(&btp->bt_io_count); |
| list_lru_destroy(&btp->bt_lru); |
| |
| 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; |
| |
| if (xfs_setsize_buftarg_early(btp, bdev)) |
| goto error; |
| |
| if (list_lru_init(&btp->bt_lru)) |
| goto error; |
| |
| if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL)) |
| 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; |
| } |
| |
| /* |
| * Cancel a delayed write list. |
| * |
| * Remove each buffer from the list, clear the delwri queue flag and drop the |
| * associated buffer reference. |
| */ |
| void |
| xfs_buf_delwri_cancel( |
| struct list_head *list) |
| { |
| struct xfs_buf *bp; |
| |
| while (!list_empty(list)) { |
| bp = list_first_entry(list, struct xfs_buf, b_list); |
| |
| xfs_buf_lock(bp); |
| bp->b_flags &= ~_XBF_DELWRI_Q; |
| list_del_init(&bp->b_list); |
| xfs_buf_relse(bp); |
| } |
| } |
| |
| /* |
| * 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; |
| } |
| |
| /* |
| * submit buffers for write. |
| * |
| * When we have a large buffer list, we do not want to hold all the buffers |
| * locked while we block on the request queue waiting for IO dispatch. To avoid |
| * this problem, we lock and submit buffers in groups of 50, thereby minimising |
| * the lock hold times for lists which may contain thousands of objects. |
| * |
| * To do this, we sort the buffer list before we walk the list to lock and |
| * submit buffers, and we plug and unplug around each group of buffers we |
| * submit. |
| */ |
| static int |
| xfs_buf_delwri_submit_buffers( |
| struct list_head *buffer_list, |
| struct list_head *wait_list) |
| { |
| struct xfs_buf *bp, *n; |
| LIST_HEAD (submit_list); |
| int pinned = 0; |
| struct blk_plug plug; |
| |
| list_sort(NULL, buffer_list, xfs_buf_cmp); |
| |
| blk_start_plug(&plug); |
| list_for_each_entry_safe(bp, n, buffer_list, b_list) { |
| if (!wait_list) { |
| 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; |
| } |
| |
| trace_xfs_buf_delwri_split(bp, _RET_IP_); |
| |
| /* |
| * 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. We need to move the buffer onto the io_list |
| * at this point so the caller can still access it. |
| */ |
| bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_WRITE_FAIL); |
| bp->b_flags |= XBF_WRITE | XBF_ASYNC; |
| if (wait_list) { |
| xfs_buf_hold(bp); |
| list_move_tail(&bp->b_list, wait_list); |
| } 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) |
| { |
| return xfs_buf_delwri_submit_buffers(buffer_list, NULL); |
| } |
| |
| /* |
| * 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 (wait_list); |
| int error = 0, error2; |
| struct xfs_buf *bp; |
| |
| xfs_buf_delwri_submit_buffers(buffer_list, &wait_list); |
| |
| /* Wait for IO to complete. */ |
| while (!list_empty(&wait_list)) { |
| bp = list_first_entry(&wait_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; |
| } |
| |
| /* |
| * Push a single buffer on a delwri queue. |
| * |
| * The purpose of this function is to submit a single buffer of a delwri queue |
| * and return with the buffer still on the original queue. The waiting delwri |
| * buffer submission infrastructure guarantees transfer of the delwri queue |
| * buffer reference to a temporary wait list. We reuse this infrastructure to |
| * transfer the buffer back to the original queue. |
| * |
| * Note the buffer transitions from the queued state, to the submitted and wait |
| * listed state and back to the queued state during this call. The buffer |
| * locking and queue management logic between _delwri_pushbuf() and |
| * _delwri_queue() guarantee that the buffer cannot be queued to another list |
| * before returning. |
| */ |
| int |
| xfs_buf_delwri_pushbuf( |
| struct xfs_buf *bp, |
| struct list_head *buffer_list) |
| { |
| LIST_HEAD (submit_list); |
| int error; |
| |
| ASSERT(bp->b_flags & _XBF_DELWRI_Q); |
| |
| trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_); |
| |
| /* |
| * Isolate the buffer to a new local list so we can submit it for I/O |
| * independently from the rest of the original list. |
| */ |
| xfs_buf_lock(bp); |
| list_move(&bp->b_list, &submit_list); |
| xfs_buf_unlock(bp); |
| |
| /* |
| * Delwri submission clears the DELWRI_Q buffer flag and returns with |
| * the buffer on the wait list with an associated reference. Rather than |
| * bounce the buffer from a local wait list back to the original list |
| * after I/O completion, reuse the original list as the wait list. |
| */ |
| xfs_buf_delwri_submit_buffers(&submit_list, buffer_list); |
| |
| /* |
| * The buffer is now under I/O and wait listed as during typical delwri |
| * submission. Lock the buffer to wait for I/O completion. Rather than |
| * remove the buffer from the wait list and release the reference, we |
| * want to return with the buffer queued to the original list. The |
| * buffer already sits on the original list with a wait list reference, |
| * however. If we let the queue inherit that wait list reference, all we |
| * need to do is reset the DELWRI_Q flag. |
| */ |
| xfs_buf_lock(bp); |
| error = bp->b_error; |
| bp->b_flags |= _XBF_DELWRI_Q; |
| xfs_buf_unlock(bp); |
| |
| 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); |
| } |