diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c index a5a260fab824..d45b2cdee6c4 100644 --- a/fs/xfs/linux-2.6/xfs_buf.c +++ b/fs/xfs/linux-2.6/xfs_buf.c @@ -93,75 +93,6 @@ xfs_buf_vmap_len( return (bp->b_page_count * PAGE_SIZE) - bp->b_offset; } -/* - * Page Region interfaces. - * - * For pages in filesystems where the blocksize is smaller than the - * pagesize, we use the page->private field (long) to hold a bitmap - * of uptodate regions within the page. - * - * Each such region is "bytes per page / bits per long" bytes long. - * - * NBPPR == number-of-bytes-per-page-region - * BTOPR == bytes-to-page-region (rounded up) - * BTOPRT == bytes-to-page-region-truncated (rounded down) - */ -#if (BITS_PER_LONG == 32) -#define PRSHIFT (PAGE_CACHE_SHIFT - 5) /* (32 == 1<<5) */ -#elif (BITS_PER_LONG == 64) -#define PRSHIFT (PAGE_CACHE_SHIFT - 6) /* (64 == 1<<6) */ -#else -#error BITS_PER_LONG must be 32 or 64 -#endif -#define NBPPR (PAGE_CACHE_SIZE/BITS_PER_LONG) -#define BTOPR(b) (((unsigned int)(b) + (NBPPR - 1)) >> PRSHIFT) -#define BTOPRT(b) (((unsigned int)(b) >> PRSHIFT)) - -STATIC unsigned long -page_region_mask( - size_t offset, - size_t length) -{ - unsigned long mask; - int first, final; - - first = BTOPR(offset); - final = BTOPRT(offset + length - 1); - first = min(first, final); - - mask = ~0UL; - mask <<= BITS_PER_LONG - (final - first); - mask >>= BITS_PER_LONG - (final); - - ASSERT(offset + length <= PAGE_CACHE_SIZE); - ASSERT((final - first) < BITS_PER_LONG && (final - first) >= 0); - - return mask; -} - -STATIC void -set_page_region( - struct page *page, - size_t offset, - size_t length) -{ - set_page_private(page, - page_private(page) | page_region_mask(offset, length)); - if (page_private(page) == ~0UL) - SetPageUptodate(page); -} - -STATIC int -test_page_region( - struct page *page, - size_t offset, - size_t length) -{ - unsigned long mask = page_region_mask(offset, length); - - return (mask && (page_private(page) & mask) == mask); -} - /* * xfs_buf_lru_add - add a buffer to the LRU. * @@ -332,7 +263,7 @@ xfs_buf_free( ASSERT(list_empty(&bp->b_lru)); - if (bp->b_flags & (_XBF_PAGE_CACHE|_XBF_PAGES)) { + if (bp->b_flags & _XBF_PAGES) { uint i; if (xfs_buf_is_vmapped(bp)) @@ -342,25 +273,22 @@ xfs_buf_free( for (i = 0; i < bp->b_page_count; i++) { struct page *page = bp->b_pages[i]; - if (bp->b_flags & _XBF_PAGE_CACHE) - ASSERT(!PagePrivate(page)); - page_cache_release(page); + __free_page(page); } - } + } else if (bp->b_flags & _XBF_KMEM) + kmem_free(bp->b_addr); _xfs_buf_free_pages(bp); xfs_buf_deallocate(bp); } /* - * Finds all pages for buffer in question and builds it's page list. + * Allocates all the pages for buffer in question and builds it's page list. */ STATIC int -_xfs_buf_lookup_pages( +xfs_buf_allocate_memory( xfs_buf_t *bp, uint flags) { - struct address_space *mapping = bp->b_target->bt_mapping; - size_t blocksize = bp->b_target->bt_bsize; size_t size = bp->b_count_desired; size_t nbytes, offset; gfp_t gfp_mask = xb_to_gfp(flags); @@ -369,29 +297,55 @@ _xfs_buf_lookup_pages( xfs_off_t 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. + */ + if (bp->b_buffer_length < PAGE_SIZE) { + bp->b_addr = kmem_alloc(bp->b_buffer_length, xb_to_km(flags)); + if (!bp->b_addr) { + /* low memory - use alloc_page loop instead */ + goto use_alloc_page; + } + + if (((unsigned long)(bp->b_addr + bp->b_buffer_length - 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_MAPPED | _XBF_KMEM; + return 0; + } + +use_alloc_page: end = bp->b_file_offset + bp->b_buffer_length; page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset); - error = _xfs_buf_get_pages(bp, page_count, flags); if (unlikely(error)) return error; - bp->b_flags |= _XBF_PAGE_CACHE; offset = bp->b_offset; - first = bp->b_file_offset >> PAGE_CACHE_SHIFT; + first = bp->b_file_offset >> PAGE_SHIFT; + bp->b_flags |= _XBF_PAGES; for (i = 0; i < bp->b_page_count; i++) { struct page *page; uint retries = 0; - - retry: - page = find_or_create_page(mapping, first + i, gfp_mask); +retry: + page = alloc_page(gfp_mask); if (unlikely(page == NULL)) { if (flags & XBF_READ_AHEAD) { bp->b_page_count = i; - for (i = 0; i < bp->b_page_count; i++) - unlock_page(bp->b_pages[i]); - return -ENOMEM; + error = ENOMEM; + goto out_free_pages; } /* @@ -412,33 +366,16 @@ _xfs_buf_lookup_pages( XFS_STATS_INC(xb_page_found); - nbytes = min_t(size_t, size, PAGE_CACHE_SIZE - offset); + nbytes = min_t(size_t, size, PAGE_SIZE - offset); size -= nbytes; - - ASSERT(!PagePrivate(page)); - if (!PageUptodate(page)) { - page_count--; - if (blocksize >= PAGE_CACHE_SIZE) { - if (flags & XBF_READ) - bp->b_flags |= _XBF_PAGE_LOCKED; - } else if (!PagePrivate(page)) { - if (test_page_region(page, offset, nbytes)) - page_count++; - } - } - bp->b_pages[i] = page; offset = 0; } + return 0; - if (!(bp->b_flags & _XBF_PAGE_LOCKED)) { - for (i = 0; i < bp->b_page_count; i++) - unlock_page(bp->b_pages[i]); - } - - if (page_count == bp->b_page_count) - bp->b_flags |= XBF_DONE; - +out_free_pages: + for (i = 0; i < bp->b_page_count; i++) + __free_page(bp->b_pages[i]); return error; } @@ -450,8 +387,9 @@ _xfs_buf_map_pages( xfs_buf_t *bp, uint flags) { - /* A single page buffer is always mappable */ + 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; bp->b_flags |= XBF_MAPPED; } else if (flags & XBF_MAPPED) { @@ -576,9 +514,14 @@ _xfs_buf_find( } } + /* + * 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); - bp->b_flags &= XBF_MAPPED; + bp->b_flags &= XBF_MAPPED | _XBF_KMEM | _XBF_PAGES; } trace_xfs_buf_find(bp, flags, _RET_IP_); @@ -599,7 +542,7 @@ xfs_buf_get( xfs_buf_flags_t flags) { xfs_buf_t *bp, *new_bp; - int error = 0, i; + int error = 0; new_bp = xfs_buf_allocate(flags); if (unlikely(!new_bp)) @@ -607,7 +550,7 @@ xfs_buf_get( bp = _xfs_buf_find(target, ioff, isize, flags, new_bp); if (bp == new_bp) { - error = _xfs_buf_lookup_pages(bp, flags); + error = xfs_buf_allocate_memory(bp, flags); if (error) goto no_buffer; } else { @@ -616,9 +559,6 @@ xfs_buf_get( return NULL; } - for (i = 0; i < bp->b_page_count; i++) - mark_page_accessed(bp->b_pages[i]); - if (!(bp->b_flags & XBF_MAPPED)) { error = _xfs_buf_map_pages(bp, flags); if (unlikely(error)) { @@ -719,8 +659,7 @@ xfs_buf_readahead( { struct backing_dev_info *bdi; - bdi = target->bt_mapping->backing_dev_info; - if (bdi_read_congested(bdi)) + if (bdi_read_congested(target->bt_bdi)) return; xfs_buf_read(target, ioff, isize, @@ -798,10 +737,10 @@ xfs_buf_associate_memory( size_t buflen; int page_count; - pageaddr = (unsigned long)mem & PAGE_CACHE_MASK; + pageaddr = (unsigned long)mem & PAGE_MASK; offset = (unsigned long)mem - pageaddr; - buflen = PAGE_CACHE_ALIGN(len + offset); - page_count = buflen >> PAGE_CACHE_SHIFT; + buflen = PAGE_ALIGN(len + offset); + page_count = buflen >> PAGE_SHIFT; /* Free any previous set of page pointers */ if (bp->b_pages) @@ -818,13 +757,12 @@ xfs_buf_associate_memory( for (i = 0; i < bp->b_page_count; i++) { bp->b_pages[i] = mem_to_page((void *)pageaddr); - pageaddr += PAGE_CACHE_SIZE; + pageaddr += PAGE_SIZE; } bp->b_count_desired = len; bp->b_buffer_length = buflen; bp->b_flags |= XBF_MAPPED; - bp->b_flags &= ~_XBF_PAGE_LOCKED; return 0; } @@ -931,20 +869,7 @@ xfs_buf_rele( /* - * Mutual exclusion on buffers. Locking model: - * - * Buffers associated with inodes for which buffer locking - * is not enabled are not protected by semaphores, and are - * assumed to be exclusively owned by the caller. There is a - * spinlock in the buffer, used by the caller when concurrent - * access is possible. - */ - -/* - * Locks a buffer object, if it is not already locked. Note that this in - * no way locks the underlying pages, so it is only useful for - * synchronizing concurrent use of buffer objects, not for synchronizing - * independent access to the underlying pages. + * 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 @@ -978,10 +903,7 @@ xfs_buf_lock_value( } /* - * Locks a buffer object. - * Note that this in no way locks the underlying pages, so it is only - * useful for synchronizing concurrent use of buffer objects, not for - * synchronizing independent access to the underlying pages. + * 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 @@ -998,7 +920,7 @@ xfs_buf_lock( if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE)) xfs_log_force(bp->b_target->bt_mount, 0); if (atomic_read(&bp->b_io_remaining)) - blk_run_address_space(bp->b_target->bt_mapping); + blk_run_backing_dev(bp->b_target->bt_bdi, NULL); down(&bp->b_sema); XB_SET_OWNER(bp); @@ -1043,7 +965,7 @@ xfs_buf_wait_unpin( if (atomic_read(&bp->b_pin_count) == 0) break; if (atomic_read(&bp->b_io_remaining)) - blk_run_address_space(bp->b_target->bt_mapping); + blk_run_backing_dev(bp->b_target->bt_bdi, NULL); schedule(); } remove_wait_queue(&bp->b_waiters, &wait); @@ -1256,10 +1178,8 @@ _xfs_buf_ioend( xfs_buf_t *bp, int schedule) { - if (atomic_dec_and_test(&bp->b_io_remaining) == 1) { - bp->b_flags &= ~_XBF_PAGE_LOCKED; + if (atomic_dec_and_test(&bp->b_io_remaining) == 1) xfs_buf_ioend(bp, schedule); - } } STATIC void @@ -1268,35 +1188,12 @@ xfs_buf_bio_end_io( int error) { xfs_buf_t *bp = (xfs_buf_t *)bio->bi_private; - unsigned int blocksize = bp->b_target->bt_bsize; - struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1; xfs_buf_ioerror(bp, -error); if (!error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ)) invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp)); - do { - struct page *page = bvec->bv_page; - - ASSERT(!PagePrivate(page)); - if (unlikely(bp->b_error)) { - if (bp->b_flags & XBF_READ) - ClearPageUptodate(page); - } else if (blocksize >= PAGE_CACHE_SIZE) { - SetPageUptodate(page); - } else if (!PagePrivate(page) && - (bp->b_flags & _XBF_PAGE_CACHE)) { - set_page_region(page, bvec->bv_offset, bvec->bv_len); - } - - if (--bvec >= bio->bi_io_vec) - prefetchw(&bvec->bv_page->flags); - - if (bp->b_flags & _XBF_PAGE_LOCKED) - unlock_page(page); - } while (bvec >= bio->bi_io_vec); - _xfs_buf_ioend(bp, 1); bio_put(bio); } @@ -1310,7 +1207,6 @@ _xfs_buf_ioapply( int offset = bp->b_offset; int size = bp->b_count_desired; sector_t sector = bp->b_bn; - unsigned int blocksize = bp->b_target->bt_bsize; total_nr_pages = bp->b_page_count; map_i = 0; @@ -1331,29 +1227,6 @@ _xfs_buf_ioapply( (bp->b_flags & XBF_READ_AHEAD) ? READA : READ; } - /* Special code path for reading a sub page size buffer in -- - * we populate up the whole page, and hence the other metadata - * in the same page. This optimization is only valid when the - * filesystem block size is not smaller than the page size. - */ - if ((bp->b_buffer_length < PAGE_CACHE_SIZE) && - ((bp->b_flags & (XBF_READ|_XBF_PAGE_LOCKED)) == - (XBF_READ|_XBF_PAGE_LOCKED)) && - (blocksize >= PAGE_CACHE_SIZE)) { - bio = bio_alloc(GFP_NOIO, 1); - - bio->bi_bdev = bp->b_target->bt_bdev; - bio->bi_sector = sector - (offset >> BBSHIFT); - bio->bi_end_io = xfs_buf_bio_end_io; - bio->bi_private = bp; - - bio_add_page(bio, bp->b_pages[0], PAGE_CACHE_SIZE, 0); - size = 0; - - atomic_inc(&bp->b_io_remaining); - - goto submit_io; - } next_chunk: atomic_inc(&bp->b_io_remaining); @@ -1367,8 +1240,9 @@ _xfs_buf_ioapply( bio->bi_end_io = xfs_buf_bio_end_io; bio->bi_private = bp; + for (; size && nr_pages; nr_pages--, map_i++) { - int rbytes, nbytes = PAGE_CACHE_SIZE - offset; + int rbytes, nbytes = PAGE_SIZE - offset; if (nbytes > size) nbytes = size; @@ -1383,7 +1257,6 @@ _xfs_buf_ioapply( total_nr_pages--; } -submit_io: if (likely(bio->bi_size)) { if (xfs_buf_is_vmapped(bp)) { flush_kernel_vmap_range(bp->b_addr, @@ -1393,18 +1266,7 @@ _xfs_buf_ioapply( if (size) goto next_chunk; } else { - /* - * if we get here, no pages were added to the bio. However, - * we can't just error out here - if the pages are locked then - * we have to unlock them otherwise we can hang on a later - * access to the page. - */ xfs_buf_ioerror(bp, EIO); - if (bp->b_flags & _XBF_PAGE_LOCKED) { - int i; - for (i = 0; i < bp->b_page_count; i++) - unlock_page(bp->b_pages[i]); - } bio_put(bio); } } @@ -1450,7 +1312,7 @@ xfs_buf_iowait( trace_xfs_buf_iowait(bp, _RET_IP_); if (atomic_read(&bp->b_io_remaining)) - blk_run_address_space(bp->b_target->bt_mapping); + blk_run_backing_dev(bp->b_target->bt_bdi, NULL); wait_for_completion(&bp->b_iowait); trace_xfs_buf_iowait_done(bp, _RET_IP_); @@ -1468,8 +1330,8 @@ xfs_buf_offset( return XFS_BUF_PTR(bp) + offset; offset += bp->b_offset; - page = bp->b_pages[offset >> PAGE_CACHE_SHIFT]; - return (xfs_caddr_t)page_address(page) + (offset & (PAGE_CACHE_SIZE-1)); + page = bp->b_pages[offset >> PAGE_SHIFT]; + return (xfs_caddr_t)page_address(page) + (offset & (PAGE_SIZE-1)); } /* @@ -1491,9 +1353,9 @@ xfs_buf_iomove( page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)]; cpoff = xfs_buf_poff(boff + bp->b_offset); csize = min_t(size_t, - PAGE_CACHE_SIZE-cpoff, bp->b_count_desired-boff); + PAGE_SIZE-cpoff, bp->b_count_desired-boff); - ASSERT(((csize + cpoff) <= PAGE_CACHE_SIZE)); + ASSERT(((csize + cpoff) <= PAGE_SIZE)); switch (mode) { case XBRW_ZERO: @@ -1606,7 +1468,6 @@ xfs_free_buftarg( xfs_flush_buftarg(btp, 1); if (mp->m_flags & XFS_MOUNT_BARRIER) xfs_blkdev_issue_flush(btp); - iput(btp->bt_mapping->host); kthread_stop(btp->bt_task); kmem_free(btp); @@ -1630,15 +1491,6 @@ xfs_setsize_buftarg_flags( return EINVAL; } - if (verbose && - (PAGE_CACHE_SIZE / BITS_PER_LONG) > sectorsize) { - printk(KERN_WARNING - "XFS: %u byte sectors in use on device %s. " - "This is suboptimal; %u or greater is ideal.\n", - sectorsize, XFS_BUFTARG_NAME(btp), - (unsigned int)PAGE_CACHE_SIZE / BITS_PER_LONG); - } - return 0; } @@ -1653,7 +1505,7 @@ xfs_setsize_buftarg_early( struct block_device *bdev) { return xfs_setsize_buftarg_flags(btp, - PAGE_CACHE_SIZE, bdev_logical_block_size(bdev), 0); + PAGE_SIZE, bdev_logical_block_size(bdev), 0); } int @@ -1665,41 +1517,6 @@ xfs_setsize_buftarg( return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1); } -STATIC int -xfs_mapping_buftarg( - xfs_buftarg_t *btp, - struct block_device *bdev) -{ - struct backing_dev_info *bdi; - struct inode *inode; - struct address_space *mapping; - static const struct address_space_operations mapping_aops = { - .sync_page = block_sync_page, - .migratepage = fail_migrate_page, - }; - - inode = new_inode(bdev->bd_inode->i_sb); - if (!inode) { - printk(KERN_WARNING - "XFS: Cannot allocate mapping inode for device %s\n", - XFS_BUFTARG_NAME(btp)); - return ENOMEM; - } - inode->i_ino = get_next_ino(); - inode->i_mode = S_IFBLK; - inode->i_bdev = bdev; - inode->i_rdev = bdev->bd_dev; - bdi = blk_get_backing_dev_info(bdev); - if (!bdi) - bdi = &default_backing_dev_info; - mapping = &inode->i_data; - mapping->a_ops = &mapping_aops; - mapping->backing_dev_info = bdi; - mapping_set_gfp_mask(mapping, GFP_NOFS); - btp->bt_mapping = mapping; - return 0; -} - STATIC int xfs_alloc_delwrite_queue( xfs_buftarg_t *btp, @@ -1728,12 +1545,14 @@ xfs_alloc_buftarg( btp->bt_mount = mp; btp->bt_dev = bdev->bd_dev; btp->bt_bdev = bdev; + btp->bt_bdi = blk_get_backing_dev_info(bdev); + if (!btp->bt_bdi) + goto error; + INIT_LIST_HEAD(&btp->bt_lru); spin_lock_init(&btp->bt_lru_lock); if (xfs_setsize_buftarg_early(btp, bdev)) goto error; - if (xfs_mapping_buftarg(btp, bdev)) - goto error; if (xfs_alloc_delwrite_queue(btp, fsname)) goto error; btp->bt_shrinker.shrink = xfs_buftarg_shrink; @@ -1955,7 +1774,7 @@ xfsbufd( count++; } if (count) - blk_run_address_space(target->bt_mapping); + blk_run_backing_dev(target->bt_bdi, NULL); } while (!kthread_should_stop()); @@ -2003,7 +1822,7 @@ xfs_flush_buftarg( if (wait) { /* Expedite and wait for IO to complete. */ - blk_run_address_space(target->bt_mapping); + blk_run_backing_dev(target->bt_bdi, NULL); while (!list_empty(&wait_list)) { bp = list_first_entry(&wait_list, struct xfs_buf, b_list); diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h index cbe65950e524..a9a1c4512645 100644 --- a/fs/xfs/linux-2.6/xfs_buf.h +++ b/fs/xfs/linux-2.6/xfs_buf.h @@ -61,30 +61,11 @@ typedef enum { #define XBF_DONT_BLOCK (1 << 16)/* do not block in current thread */ /* flags used only internally */ -#define _XBF_PAGE_CACHE (1 << 17)/* backed by pagecache */ #define _XBF_PAGES (1 << 18)/* backed by refcounted pages */ #define _XBF_RUN_QUEUES (1 << 19)/* run block device task queue */ +#define _XBF_KMEM (1 << 20)/* backed by heap memory */ #define _XBF_DELWRI_Q (1 << 21)/* buffer on delwri queue */ -/* - * Special flag for supporting metadata blocks smaller than a FSB. - * - * In this case we can have multiple xfs_buf_t on a single page and - * need to lock out concurrent xfs_buf_t readers as they only - * serialise access to the buffer. - * - * If the FSB size >= PAGE_CACHE_SIZE case, we have no serialisation - * between reads of the page. Hence we can have one thread read the - * page and modify it, but then race with another thread that thinks - * the page is not up-to-date and hence reads it again. - * - * The result is that the first modifcation to the page is lost. - * This sort of AGF/AGI reading race can happen when unlinking inodes - * that require truncation and results in the AGI unlinked list - * modifications being lost. - */ -#define _XBF_PAGE_LOCKED (1 << 22) - typedef unsigned int xfs_buf_flags_t; #define XFS_BUF_FLAGS \ @@ -100,12 +81,10 @@ typedef unsigned int xfs_buf_flags_t; { XBF_LOCK, "LOCK" }, /* should never be set */\ { XBF_TRYLOCK, "TRYLOCK" }, /* ditto */\ { XBF_DONT_BLOCK, "DONT_BLOCK" }, /* ditto */\ - { _XBF_PAGE_CACHE, "PAGE_CACHE" }, \ { _XBF_PAGES, "PAGES" }, \ { _XBF_RUN_QUEUES, "RUN_QUEUES" }, \ - { _XBF_DELWRI_Q, "DELWRI_Q" }, \ - { _XBF_PAGE_LOCKED, "PAGE_LOCKED" } - + { _XBF_KMEM, "KMEM" }, \ + { _XBF_DELWRI_Q, "DELWRI_Q" } typedef enum { XBT_FORCE_SLEEP = 0, @@ -120,7 +99,7 @@ typedef struct xfs_bufhash { typedef struct xfs_buftarg { dev_t bt_dev; struct block_device *bt_bdev; - struct address_space *bt_mapping; + struct backing_dev_info *bt_bdi; struct xfs_mount *bt_mount; unsigned int bt_bsize; unsigned int bt_sshift; @@ -139,17 +118,6 @@ typedef struct xfs_buftarg { unsigned int bt_lru_nr; } xfs_buftarg_t; -/* - * xfs_buf_t: Buffer structure for pagecache-based buffers - * - * This buffer structure is used by the pagecache buffer management routines - * to refer to an assembly of pages forming a logical buffer. - * - * The buffer structure is used on a temporary basis only, and discarded when - * released. The real data storage is recorded in the pagecache. Buffers are - * hashed to the block device on which the file system resides. - */ - struct xfs_buf; typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);