diff options
| -rw-r--r-- | fs/btrfs/tree-log.c | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 66f87156882f..9c45431e69ab 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -4197,6 +4197,107 @@ static int btrfs_log_all_xattrs(struct btrfs_trans_handle *trans, return 0; } +/* + * If the no holes feature is enabled we need to make sure any hole between the + * last extent and the i_size of our inode is explicitly marked in the log. This + * is to make sure that doing something like: + * + * 1) create file with 128Kb of data + * 2) truncate file to 64Kb + * 3) truncate file to 256Kb + * 4) fsync file + * 5) <crash/power failure> + * 6) mount fs and trigger log replay + * + * Will give us a file with a size of 256Kb, the first 64Kb of data match what + * the file had in its first 64Kb of data at step 1 and the last 192Kb of the + * file correspond to a hole. The presence of explicit holes in a log tree is + * what guarantees that log replay will remove/adjust file extent items in the + * fs/subvol tree. + * + * Here we do not need to care about holes between extents, that is already done + * by copy_items(). We also only need to do this in the full sync path, where we + * lookup for extents from the fs/subvol tree only. In the fast path case, we + * lookup the list of modified extent maps and if any represents a hole, we + * insert a corresponding extent representing a hole in the log tree. + */ +static int btrfs_log_trailing_hole(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct inode *inode, + struct btrfs_path *path) +{ + int ret; + struct btrfs_key key; + u64 hole_start; + u64 hole_size; + struct extent_buffer *leaf; + struct btrfs_root *log = root->log_root; + const u64 ino = btrfs_ino(inode); + const u64 i_size = i_size_read(inode); + + if (!btrfs_fs_incompat(root->fs_info, NO_HOLES)) + return 0; + + key.objectid = ino; + key.type = BTRFS_EXTENT_DATA_KEY; + key.offset = (u64)-1; + + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + ASSERT(ret != 0); + if (ret < 0) + return ret; + + ASSERT(path->slots[0] > 0); + path->slots[0]--; + leaf = path->nodes[0]; + btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); + + if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) { + /* inode does not have any extents */ + hole_start = 0; + hole_size = i_size; + } else { + struct btrfs_file_extent_item *extent; + u64 len; + + /* + * If there's an extent beyond i_size, an explicit hole was + * already inserted by copy_items(). + */ + if (key.offset >= i_size) + return 0; + + extent = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + + if (btrfs_file_extent_type(leaf, extent) == + BTRFS_FILE_EXTENT_INLINE) { + len = btrfs_file_extent_inline_len(leaf, + path->slots[0], + extent); + ASSERT(len == i_size); + return 0; + } + + len = btrfs_file_extent_num_bytes(leaf, extent); + /* Last extent goes beyond i_size, no need to log a hole. */ + if (key.offset + len > i_size) + return 0; + hole_start = key.offset + len; + hole_size = i_size - hole_start; + } + btrfs_release_path(path); + + /* Last extent ends at i_size. */ + if (hole_size == 0) + return 0; + + hole_size = ALIGN(hole_size, root->sectorsize); + ret = btrfs_insert_file_extent(trans, log, ino, hole_start, 0, 0, + hole_size, 0, hole_size, 0, 0, 0); + return ret; +} + /* log a single inode in the tree log. * At least one parent directory for this inode must exist in the tree * or be logged already. @@ -4460,6 +4561,13 @@ next_slot: err = btrfs_log_all_xattrs(trans, root, inode, path, dst_path); if (err) goto out_unlock; + if (max_key.type >= BTRFS_EXTENT_DATA_KEY && !fast_search) { + btrfs_release_path(path); + btrfs_release_path(dst_path); + err = btrfs_log_trailing_hole(trans, root, inode, path); + if (err) + goto out_unlock; + } log_extents: btrfs_release_path(path); btrfs_release_path(dst_path); |