diff options
Diffstat (limited to 'fs/btrfs/extent_io.c')
| -rw-r--r-- | fs/btrfs/extent_io.c | 513 |
1 files changed, 366 insertions, 147 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index d74e6af9b53..96fcfa522da 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -10,6 +10,7 @@ #include <linux/swap.h> #include <linux/writeback.h> #include <linux/pagevec.h> +#include <linux/prefetch.h> #include "extent_io.h" #include "extent_map.h" #include "compat.h" @@ -104,7 +105,7 @@ void extent_io_tree_init(struct extent_io_tree *tree, struct address_space *mapping, gfp_t mask) { tree->state = RB_ROOT; - tree->buffer = RB_ROOT; + INIT_RADIX_TREE(&tree->buffer, GFP_ATOMIC); tree->ops = NULL; tree->dirty_bytes = 0; spin_lock_init(&tree->lock); @@ -235,50 +236,6 @@ static inline struct rb_node *tree_search(struct extent_io_tree *tree, return ret; } -static struct extent_buffer *buffer_tree_insert(struct extent_io_tree *tree, - u64 offset, struct rb_node *node) -{ - struct rb_root *root = &tree->buffer; - struct rb_node **p = &root->rb_node; - struct rb_node *parent = NULL; - struct extent_buffer *eb; - - while (*p) { - parent = *p; - eb = rb_entry(parent, struct extent_buffer, rb_node); - - if (offset < eb->start) - p = &(*p)->rb_left; - else if (offset > eb->start) - p = &(*p)->rb_right; - else - return eb; - } - - rb_link_node(node, parent, p); - rb_insert_color(node, root); - return NULL; -} - -static struct extent_buffer *buffer_search(struct extent_io_tree *tree, - u64 offset) -{ - struct rb_root *root = &tree->buffer; - struct rb_node *n = root->rb_node; - struct extent_buffer *eb; - - while (n) { - eb = rb_entry(n, struct extent_buffer, rb_node); - if (offset < eb->start) - n = n->rb_left; - else if (offset > eb->start) - n = n->rb_right; - else - return eb; - } - return NULL; -} - static void merge_cb(struct extent_io_tree *tree, struct extent_state *new, struct extent_state *other) { @@ -734,6 +691,15 @@ static void cache_state(struct extent_state *state, } } +static void uncache_state(struct extent_state **cached_ptr) +{ + if (cached_ptr && (*cached_ptr)) { + struct extent_state *state = *cached_ptr; + *cached_ptr = NULL; + free_extent_state(state); + } +} + /* * set some bits on a range in the tree. This may require allocations or * sleeping, so the gfp mask is used to indicate what is allowed. @@ -984,10 +950,10 @@ static int clear_extent_new(struct extent_io_tree *tree, u64 start, u64 end, } int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end, - gfp_t mask) + struct extent_state **cached_state, gfp_t mask) { - return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, NULL, - NULL, mask); + return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, + NULL, cached_state, mask); } static int clear_extent_uptodate(struct extent_io_tree *tree, u64 start, @@ -1056,8 +1022,7 @@ int unlock_extent_cached(struct extent_io_tree *tree, u64 start, u64 end, mask); } -int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end, - gfp_t mask) +int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask) { return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, NULL, mask); @@ -1477,12 +1442,13 @@ int extent_clear_unlock_delalloc(struct inode *inode, */ u64 count_range_bits(struct extent_io_tree *tree, u64 *start, u64 search_end, u64 max_bytes, - unsigned long bits) + unsigned long bits, int contig) { struct rb_node *node; struct extent_state *state; u64 cur_start = *start; u64 total_bytes = 0; + u64 last = 0; int found = 0; if (search_end <= cur_start) { @@ -1507,7 +1473,9 @@ u64 count_range_bits(struct extent_io_tree *tree, state = rb_entry(node, struct extent_state, rb_node); if (state->start > search_end) break; - if (state->end >= cur_start && (state->state & bits)) { + if (contig && found && state->start > last + 1) + break; + if (state->end >= cur_start && (state->state & bits) == bits) { total_bytes += min(search_end, state->end) + 1 - max(cur_start, state->start); if (total_bytes >= max_bytes) @@ -1516,6 +1484,9 @@ u64 count_range_bits(struct extent_io_tree *tree, *start = state->start; found = 1; } + last = state->end; + } else if (contig && found) { + break; } node = rb_next(node); if (!node) @@ -1773,6 +1744,9 @@ static void end_bio_extent_readpage(struct bio *bio, int err) do { struct page *page = bvec->bv_page; + struct extent_state *cached = NULL; + struct extent_state *state; + tree = &BTRFS_I(page->mapping->host)->io_tree; start = ((u64)page->index << PAGE_CACHE_SHIFT) + @@ -1787,9 +1761,20 @@ static void end_bio_extent_readpage(struct bio *bio, int err) if (++bvec <= bvec_end) prefetchw(&bvec->bv_page->flags); + spin_lock(&tree->lock); + state = find_first_extent_bit_state(tree, start, EXTENT_LOCKED); + if (state && state->start == start) { + /* + * take a reference on the state, unlock will drop + * the ref + */ + cache_state(state, &cached); + } + spin_unlock(&tree->lock); + if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) { ret = tree->ops->readpage_end_io_hook(page, start, end, - NULL); + state); if (ret) uptodate = 0; } @@ -1802,15 +1787,16 @@ static void end_bio_extent_readpage(struct bio *bio, int err) test_bit(BIO_UPTODATE, &bio->bi_flags); if (err) uptodate = 0; + uncache_state(&cached); continue; } } if (uptodate) { - set_extent_uptodate(tree, start, end, + set_extent_uptodate(tree, start, end, &cached, GFP_ATOMIC); } - unlock_extent(tree, start, end, GFP_ATOMIC); + unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC); if (whole_page) { if (uptodate) { @@ -1849,6 +1835,7 @@ static void end_bio_extent_preparewrite(struct bio *bio, int err) do { struct page *page = bvec->bv_page; + struct extent_state *cached = NULL; tree = &BTRFS_I(page->mapping->host)->io_tree; start = ((u64)page->index << PAGE_CACHE_SHIFT) + @@ -1859,22 +1846,23 @@ static void end_bio_extent_preparewrite(struct bio *bio, int err) prefetchw(&bvec->bv_page->flags); if (uptodate) { - set_extent_uptodate(tree, start, end, GFP_ATOMIC); + set_extent_uptodate(tree, start, end, &cached, + GFP_ATOMIC); } else { ClearPageUptodate(page); SetPageError(page); } - unlock_extent(tree, start, end, GFP_ATOMIC); + unlock_extent_cached(tree, start, end, &cached, GFP_ATOMIC); } while (bvec >= bio->bi_io_vec); bio_put(bio); } -static struct bio * -extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs, - gfp_t gfp_flags) +struct bio * +btrfs_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs, + gfp_t gfp_flags) { struct bio *bio; @@ -1901,17 +1889,15 @@ static int submit_one_bio(int rw, struct bio *bio, int mirror_num, struct page *page = bvec->bv_page; struct extent_io_tree *tree = bio->bi_private; u64 start; - u64 end; start = ((u64)page->index << PAGE_CACHE_SHIFT) + bvec->bv_offset; - end = start + bvec->bv_len - 1; bio->bi_private = NULL; bio_get(bio); if (tree->ops && tree->ops->submit_bio_hook) - tree->ops->submit_bio_hook(page->mapping->host, rw, bio, + ret = tree->ops->submit_bio_hook(page->mapping->host, rw, bio, mirror_num, bio_flags, start); else submit_bio(rw, bio); @@ -1965,7 +1951,9 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree, else nr = bio_get_nr_vecs(bdev); - bio = extent_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH); + bio = btrfs_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH); + if (!bio) + return -ENOMEM; bio_add_page(bio, page, page_size, offset); bio->bi_end_io = end_io_func; @@ -1990,6 +1978,7 @@ void set_page_extent_mapped(struct page *page) static void set_page_extent_head(struct page *page, unsigned long len) { + WARN_ON(!PagePrivate(page)); set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2); } @@ -2053,14 +2042,17 @@ static int __extent_read_full_page(struct extent_io_tree *tree, while (cur <= end) { if (cur >= last_byte) { char *userpage; + struct extent_state *cached = NULL; + iosize = PAGE_CACHE_SIZE - page_offset; userpage = kmap_atomic(page, KM_USER0); memset(userpage + page_offset, 0, iosize); flush_dcache_page(page); kunmap_atomic(userpage, KM_USER0); set_extent_uptodate(tree, cur, cur + iosize - 1, - GFP_NOFS); - unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS); + &cached, GFP_NOFS); + unlock_extent_cached(tree, cur, cur + iosize - 1, + &cached, GFP_NOFS); break; } em = get_extent(inode, page, page_offset, cur, @@ -2074,8 +2066,11 @@ static int __extent_read_full_page(struct extent_io_tree *tree, BUG_ON(extent_map_end(em) <= cur); BUG_ON(end < cur); - if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) + if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) { this_bio_flag = EXTENT_BIO_COMPRESSED; + extent_set_compress_type(&this_bio_flag, + em->compress_type); + } iosize = min(extent_map_end(em) - cur, end - cur + 1); cur_end = min(extent_map_end(em) - 1, end); @@ -2097,14 +2092,17 @@ static int __extent_read_full_page(struct extent_io_tree *tree, /* we've found a hole, just zero and go on */ if (block_start == EXTENT_MAP_HOLE) { char *userpage; + struct extent_state *cached = NULL; + userpage = kmap_atomic(page, KM_USER0); memset(userpage + page_offset, 0, iosize); flush_dcache_page(page); kunmap_atomic(userpage, KM_USER0); set_extent_uptodate(tree, cur, cur + iosize - 1, - GFP_NOFS); - unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS); + &cached, GFP_NOFS); + unlock_extent_cached(tree, cur, cur + iosize - 1, + &cached, GFP_NOFS); cur = cur + iosize; page_offset += iosize; continue; @@ -2169,7 +2167,7 @@ int extent_read_full_page(struct extent_io_tree *tree, struct page *page, ret = __extent_read_full_page(tree, page, get_extent, &bio, 0, &bio_flags); if (bio) - submit_one_bio(READ, bio, 0, bio_flags); + ret = submit_one_bio(READ, bio, 0, bio_flags); return ret; } @@ -2204,7 +2202,6 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, u64 last_byte = i_size_read(inode); u64 block_start; u64 iosize; - u64 unlock_start; sector_t sector; struct extent_state *cached_state = NULL; struct extent_map *em; @@ -2223,10 +2220,12 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, unsigned long nr_written = 0; if (wbc->sync_mode == WB_SYNC_ALL) - write_flags = WRITE_SYNC_PLUG; + write_flags = WRITE_SYNC; else write_flags = WRITE; + trace___extent_writepage(page, inode, wbc); + WARN_ON(!PageLocked(page)); pg_offset = i_size & (PAGE_CACHE_SIZE - 1); if (page->index > end_index || @@ -2329,7 +2328,6 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, if (tree->ops && tree->ops->writepage_end_io_hook) tree->ops->writepage_end_io_hook(page, start, page_end, NULL, 1); - unlock_start = page_end + 1; goto done; } @@ -2340,7 +2338,6 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, if (tree->ops && tree->ops->writepage_end_io_hook) tree->ops->writepage_end_io_hook(page, cur, page_end, NULL, 1); - unlock_start = page_end + 1; break; } em = epd->get_extent(inode, page, pg_offset, cur, @@ -2387,7 +2384,6 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, cur += iosize; pg_offset += iosize; - unlock_start = cur; continue; } /* leave this out until we have a page_mkwrite call */ @@ -2473,7 +2469,6 @@ static int extent_write_cache_pages(struct extent_io_tree *tree, pgoff_t index; pgoff_t end; /* Inclusive */ int scanned = 0; - int range_whole = 0; pagevec_init(&pvec, 0); if (wbc->range_cyclic) { @@ -2482,8 +2477,6 @@ static int extent_write_cache_pages(struct extent_io_tree *tree, } else { index = wbc->range_start >> PAGE_CACHE_SHIFT; end = wbc->range_end >> PAGE_CACHE_SHIFT; - if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) - range_whole = 1; scanned = 1; } retry: @@ -2689,7 +2682,7 @@ int extent_readpages(struct extent_io_tree *tree, prefetchw(&page->flags); list_del(&page->lru); if (!add_to_page_cache_lru(page, mapping, - page->index, GFP_KERNEL)) { + page->index, GFP_NOFS)) { __extent_read_full_page(tree, page, get_extent, &bio, 0, &bio_flags); } @@ -2823,12 +2816,17 @@ int extent_prepare_write(struct extent_io_tree *tree, NULL, 1, end_bio_extent_preparewrite, 0, 0, 0); + if (ret && !err) + err = ret; iocount++; block_start = block_start + iosize; } else { - set_extent_uptodate(tree, block_start, cur_end, + struct extent_state *cached = NULL; + + set_extent_uptodate(tree, block_start, cur_end, &cached, GFP_NOFS); - unlock_extent(tree, block_start, cur_end, GFP_NOFS); + unlock_extent_cached(tree, block_start, cur_end, + &cached, GFP_NOFS); block_start = cur_end + 1; } page_offset = block_start & (PAGE_CACHE_SIZE - 1); @@ -2867,9 +2865,17 @@ int try_release_extent_state(struct extent_map_tree *map, * at this point we can safely clear everything except the * locked bit and the nodatasum bit */ - clear_extent_bit(tree, start, end, + ret = clear_extent_bit(tree, start, end, ~(EXTENT_LOCKED | EXTENT_NODATASUM), 0, 0, NULL, mask); + + /* if clear_extent_bit failed for enomem reasons, + * we can't allow the release to continue. + */ + if (ret < 0) + ret = 0; + else + ret = 1; } return ret; } @@ -2949,49 +2955,169 @@ out: return sector; } +/* + * helper function for fiemap, which doesn't want to see any holes. + * This maps until we find something past 'last' + */ +static struct extent_map *get_extent_skip_holes(struct inode *inode, + u64 offset, + u64 last, + get_extent_t *get_extent) +{ + u64 sectorsize = BTRFS_I(inode)->root->sectorsize; + struct extent_map *em; + u64 len; + + if (offset >= last) + return NULL; + + while(1) { + len = last - offset; + if (len == 0) + break; + len = (len + sectorsize - 1) & ~(sectorsize - 1); + em = get_extent(inode, NULL, 0, offset, len, 0); + if (!em || IS_ERR(em)) + return em; + + /* if this isn't a hole return it */ + if (!test_bit(EXTENT_FLAG_VACANCY, &em->flags) && + em->block_start != EXTENT_MAP_HOLE) { + return em; + } + + /* this is a hole, advance to the next extent */ + offset = extent_map_end(em); + free_extent_map(em); + if (offset >= last) + break; + } + return NULL; +} + int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, __u64 start, __u64 len, get_extent_t *get_extent) { - int ret; + int ret = 0; u64 off = start; u64 max = start + len; u32 flags = 0; + u32 found_type; + u64 last; + u64 last_for_get_extent = 0; u64 disko = 0; + u64 isize = i_size_read(inode); + struct btrfs_key found_key; struct extent_map *em = NULL; struct extent_state *cached_state = NULL; + struct btrfs_path *path; + struct btrfs_file_extent_item *item; int end = 0; - u64 em_start = 0, em_len = 0; + u64 em_start = 0; + u64 em_len = 0; + u64 em_end = 0; unsigned long emflags; - ret = 0; if (len == 0) return -EINVAL; + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + path->leave_spinning = 1; + + /* + * lookup the last file extent. We're not using i_size here + * because there might be preallocation past i_size + */ + ret = btrfs_lookup_file_extent(NULL, BTRFS_I(inode)->root, + path, inode->i_ino, -1, 0); + if (ret < 0) { + btrfs_free_path(path); + return ret; + } + WARN_ON(!ret); + path->slots[0]--; + item = btrfs_item_ptr(path->nodes[0], path->slots[0], + struct btrfs_file_extent_item); + btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]); + found_type = btrfs_key_type(&found_key); + + /* No extents, but there might be delalloc bits */ + if (found_key.objectid != inode->i_ino || + found_type != BTRFS_EXTENT_DATA_KEY) { + /* have to trust i_size as the end */ + last = (u64)-1; + last_for_get_extent = isize; + } else { + /* + * remember the start of the last extent. There are a + * bunch of different factors that go into the length of the + * extent, so its much less complex to remember where it started + */ + last = found_key.offset; + last_for_get_extent = last + 1; + } + btrfs_free_path(path); + + /* + * we might have some extents allocated but more delalloc past those + * extents. so, we trust isize unless the start of the last extent is + * beyond isize + */ + if (last < isize) { + last = (u64)-1; + last_for_get_extent = isize; + } + lock_extent_bits(&BTRFS_I(inode)->io_tree, start, start + len, 0, &cached_state, GFP_NOFS); - em = get_extent(inode, NULL, 0, off, max - off, 0); + + em = get_extent_skip_holes(inode, off, last_for_get_extent, + get_extent); if (!em) goto out; if (IS_ERR(em)) { ret = PTR_ERR(em); goto out; } + while (!end) { - off = em->start + em->len; - if (off >= max) - end = 1; + u64 offset_in_extent; - em_start = em->start; - em_len = em->len; + /* break if the extent we found is outside the range */ + if (em->start >= max || extent_map_end(em) < off) + break; + /* + * get_extent may return an extent that starts before our + * requested range. We have to make sure the ranges + * we return to fiemap always move forward and don't + * overlap, so adjust the offsets here + */ + em_start = max(em->start, off); + + /* + * record the offset from the start of the extent + * for adjusting the disk offset below + */ + offset_in_extent = em_start - em->start; + em_end = extent_map_end(em); + em_len = em_end - em_start; + emflags = em->flags; disko = 0; flags = 0; + /* + * bump off for our next call to get_extent + */ + off = extent_map_end(em); + if (off >= max) + end = 1; + if (em->block_start == EXTENT_MAP_LAST_BYTE) { end = 1; flags |= FIEMAP_EXTENT_LAST; - } else if (em->block_start == EXTENT_MAP_HOLE) { - flags |= FIEMAP_EXTENT_UNWRITTEN; } else if (em->block_start == EXTENT_MAP_INLINE) { flags |= (FIEMAP_EXTENT_DATA_INLINE | FIEMAP_EXTENT_NOT_ALIGNED); @@ -2999,32 +3125,32 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, flags |= (FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN); } else { - disko = em->block_start; + disko = em->block_start + offset_in_extent; } if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) flags |= FIEMAP_EXTENT_ENCODED; - emflags = em->flags; free_extent_map(em); em = NULL; + if ((em_start >= last) || em_len == (u64)-1 || + (last == (u64)-1 && isize <= em_end)) { + flags |= FIEMAP_EXTENT_LAST; + end = 1; + } - if (!end) { - em = get_extent(inode, NULL, 0, off, max - off, 0); - if (!em) - goto out; - if (IS_ERR(em)) { - ret = PTR_ERR(em); - goto out; - } - emflags = em->flags; + /* now scan forward to see if this is really the last extent. */ + em = get_extent_skip_holes(inode, off, last_for_get_extent, + get_extent); + if (IS_ERR(em)) { + ret = PTR_ERR(em); + goto out; } - if (test_bit(EXTENT_FLAG_VACANCY, &emflags)) { + if (!em) { flags |= FIEMAP_EXTENT_LAST; end = 1; } - ret = fiemap_fill_next_extent(fieinfo, em_start, disko, - em_len, flags); + em_len, flags); if (ret) goto out_free; } @@ -3078,6 +3204,8 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, #endif eb = kmem_cache_zalloc(extent_buffer_cache, mask); + if (eb == NULL) + return NULL; eb->start = start; eb->len = len; spin_lock_init(&eb->lock); @@ -3104,6 +3232,39 @@ static void __free_extent_buffer(struct extent_buffer *eb) kmem_cache_free(extent_buffer_cache, eb); } +/* + * Helper for releasing extent buffer page. + */ +static void btrfs_release_extent_buffer_page(struct extent_buffer *eb, + unsigned long start_idx) +{ + unsigned long index; + struct page *page; + + if (!eb->first_page) + return; + + index = num_extent_pages(eb->start, eb->len); + if (start_idx >= index) + return; + + do { + index--; + page = extent_buffer_page(eb, index); + if (page) + page_cache_release(page); + } while (index != start_idx); +} + +/* + * Helper for releasing the extent buffer. + */ +static inline void btrfs_release_extent_buffer(struct extent_buffer *eb) +{ + btrfs_release_extent_buffer_page(eb, 0); + __free_extent_buffer(eb); +} + struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, u64 start, unsigned long len, struct page *page0, @@ -3117,16 +3278,16 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, struct page *p; struct address_space *mapping = tree->mapping; int uptodate = 1; + int ret; - spin_lock(&tree->buffer_lock); - eb = buffer_search(tree, start); - if (eb) { - atomic_inc(&eb->refs); - spin_unlock(&tree->buffer_lock); + rcu_read_lock(); + eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT); + if (eb && atomic_inc_not_zero(&eb->refs)) { + rcu_read_unlock(); mark_page_accessed(eb->first_page); return eb; } - spin_unlock(&tree->buffer_lock); + rcu_read_unlock(); eb = __alloc_extent_buffer(tree, start, len, mask); if (!eb) @@ -3160,31 +3321,59 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, } if (!PageUptodate(p)) uptodate = 0; - unlock_page(p); + + /* + * see below about how we avoid a nasty race with release page + * and why we unlock later + */ + if (i != 0) + unlock_page(p); } if (uptodate) set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); + ret = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM); + if (ret) + goto free_eb; + spin_lock(&tree->buffer_lock); - exists = buffer_tree_insert(tree, start, &eb->rb_node); - if (exists) { + ret = radix_tree_insert(&tree->buffer, start >> PAGE_CACHE_SHIFT, eb); + if (ret == -EEXIST) { + exists = radix_tree_lookup(&tree->buffer, + start >> PAGE_CACHE_SHIFT); /* add one reference for the caller */ atomic_inc(&exists->refs); spin_unlock(&tree->buffer_lock); + radix_tree_preload_end(); goto free_eb; } /* add one reference for the tree */ atomic_inc(&eb->refs); spin_unlock(&tree->buffer_lock); + radix_tree_preload_end(); + + /* + * there is a race where release page may have + * tried to find this extent buffer in the radix + * but failed. It will tell the VM it is safe to + * reclaim the, and it will clear the page private bit. + * We must make sure to set the page private bit properly + * after the extent buffer is in the radix tree so + * it doesn't get lost + */ + set_page_extent_mapped(eb->first_page); + set_page_extent_head(eb->first_page, eb->len); + if (!page0) + unlock_page(eb->first_page); return eb; free_eb: + if (eb->first_page && !page0) + unlock_page(eb->first_page); + if (!atomic_dec_and_test(&eb->refs)) return exists; - for (index = 1; index < i; index++) - page_cache_release(extent_buffer_page(eb, index)); - page_cache_release(extent_buffer_page(eb, 0)); - __free_extent_buffer(eb); + btrfs_release_extent_buffer(eb); return exists; } @@ -3194,16 +3383,16 @@ struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree, { struct extent_buffer *eb; - spin_lock(&tree->buffer_lock); - eb = buffer_search(tree, start); - if (eb) - atomic_inc(&eb->refs); - spin_unlock(&tree->buffer_lock); - - if (eb) + rcu_read_lock(); + eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT); + if (eb && atomic_inc_not_zero(&eb->refs)) { + rcu_read_unlock(); mark_page_accessed(eb->first_page); + return eb; + } + rcu_read_unlock(); - return eb; + return NULL; } void free_extent_buffer(struct extent_buffer *eb) @@ -3232,10 +3421,11 @@ int clear_extent_buffer_dirty(struct extent_io_tree *tree, continue; lock_page(page); + WARN_ON(!PagePrivate(page)); + + set_page_extent_mapped(page); if (i == 0) set_page_extent_head(page, eb->len); - else - set_page_private(page, EXTENT_PAGE_PRIVATE); clear_page_dirty_for_io(page); spin_lock_irq(&page->mapping->tree_lock); @@ -3302,7 +3492,7 @@ int set_extent_buffer_uptodate(struct extent_io_tree *tree, num_pages = num_extent_pages(eb->start, eb->len); set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1, - GFP_NOFS); + NULL, GFP_NOFS); for (i = 0; i < num_pages; i++) { page = extent_buffer_page(eb, i); if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) || @@ -3425,6 +3615,13 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, for (i = start_i; i < num_pages; i++) { page = extent_buffer_page(eb, i); + + WARN_ON(!PagePrivate(page)); + + set_page_extent_mapped(page); + if (i == 0) + set_page_extent_head(page, eb->len); + if (inc_all_pages) page_cache_get(page); if (!PageUptodate(page)) { @@ -3530,6 +3727,7 @@ int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start, "wanted %lu %lu\n", (unsigned long long)eb->start, eb->len, start, min_len); WARN_ON(1); + return -EINVAL; } p = extent_buffer_page(eb, i); @@ -3722,6 +3920,12 @@ static void move_pages(struct page *dst_page, struct page *src_page, kunmap_atomic(dst_kaddr, KM_USER0); } +static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len) +{ + unsigned long distance = (src > dst) ? src - dst : dst - src; + return distance < len; +} + static void copy_pages(struct page *dst_page, struct page *src_page, unsigned long dst_off, unsigned long src_off, unsigned long len) @@ -3729,10 +3933,12 @@ static void copy_pages(struct page *dst_page, struct page *src_page, char *dst_kaddr = kmap_atomic(dst_page, KM_USER0); char *src_kaddr; - if (dst_page != src_page) + if (dst_page != src_page) { src_kaddr = kmap_atomic(src_page, KM_USER1); - else + } else { src_kaddr = dst_kaddr; + BUG_ON(areas_overlap(src_off, dst_off, len)); + } memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len); kunmap_atomic(dst_kaddr, KM_USER0); @@ -3807,7 +4013,7 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, "len %lu len %lu\n", dst_offset, len, dst->len); BUG_ON(1); } - if (dst_offset < src_offset) { + if (!areas_overlap(src_offset, dst_offset, len)) { memcpy_extent_buffer(dst, dst_offset, src_offset, len); return; } @@ -3833,34 +4039,47 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, } } +static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head) +{ + struct extent_buffer *eb = + container_of(head, struct extent_buffer, rcu_head); + + btrfs_release_extent_buffer(eb); +} + int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page) { u64 start = page_offset(page); struct extent_buffer *eb; int ret = 1; - unsigned long i; - unsigned long num_pages; spin_lock(&tree->buffer_lock); - eb = buffer_search(tree, start); - if (!eb) - goto out; + eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT); + if (!eb) { + spin_unlock(&tree->buffer_lock); + return ret; + } - if (atomic_read(&eb->refs) > 1) { + if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) { ret = 0; goto out; } - if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) { + + /* + * set @eb->refs to 0 if it is already 1, and then release the @eb. + * Or go back. + */ + if (atomic_cmpxchg(&eb->refs, 1, 0) != 1) { ret = 0; goto out; } - /* at this point we can safely release the extent buffer */ - num_pages = num_extent_pages(eb->start, eb->len); - for (i = 0; i < num_pages; i++) - page_cache_release(extent_buffer_page(eb, i)); - rb_erase(&eb->rb_node, &tree->buffer); - __free_extent_buffer(eb); + + radix_tree_delete(&tree->buffer, start >> PAGE_CACHE_SHIFT); out: spin_unlock(&tree->buffer_lock); + + /* at this point we can safely release the extent buffer */ + if (atomic_read(&eb->refs) == 0) + call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu); return ret; } |