diff options
Diffstat (limited to 'fs/btrfs/extent_io.c')
| -rw-r--r-- | fs/btrfs/extent_io.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 1dfbe859c650..973254b1f216 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -6123,3 +6123,50 @@ int try_release_extent_buffer(struct page *page) return release_extent_buffer(eb); } + +/* + * btrfs_readahead_tree_block - attempt to readahead a child block + * @fs_info: the fs_info + * @bytenr: bytenr to read + * @gen: generation for the uptodate check, can be 0 + * + * Attempt to readahead a tree block at @bytenr. If @gen is 0 then we do a + * normal uptodate check of the eb, without checking the generation. If we have + * to read the block we will not block on anything. + */ +void btrfs_readahead_tree_block(struct btrfs_fs_info *fs_info, + u64 bytenr, u64 gen) +{ + struct extent_buffer *eb; + int ret; + + eb = btrfs_find_create_tree_block(fs_info, bytenr); + if (IS_ERR(eb)) + return; + + if (btrfs_buffer_uptodate(eb, gen, 1)) { + free_extent_buffer(eb); + return; + } + + ret = read_extent_buffer_pages(eb, WAIT_NONE, 0); + if (ret < 0) + free_extent_buffer_stale(eb); + else + free_extent_buffer(eb); +} + +/* + * btrfs_readahead_node_child - readahead a node's child block + * @node: parent node we're reading from + * @slot: slot in the parent node for the child we want to read + * + * A helper for btrfs_readahead_tree_block, we simply read the bytenr pointed at + * the slot in the node provided. + */ +void btrfs_readahead_node_child(struct extent_buffer *node, int slot) +{ + btrfs_readahead_tree_block(node->fs_info, + btrfs_node_blockptr(node, slot), + btrfs_node_ptr_generation(node, slot)); +} |