From 580f0a678ebeba85d30b6a7f22ce32c472263c72 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 23 Jan 2014 16:03:45 -0500 Subject: [PATCH] Btrfs: fix extent_from_logical to deal with skinny metadata I don't think this is an issue and I've not seen it in practice but extent_from_logical will fail to find a skinny extent because it uses btrfs_previous_item and gives it the normal extent item type. This is just not a place to use btrfs_previous_item since we care about either normal extents or skinny extents, so open code btrfs_previous_item to properly check. This would only affect metadata and the only place this is used for metadata is scrub and I'm pretty sure it's just for printing stuff out, not actually doing any work so hopefully it was never a problem other than a cosmetic one. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/backref.c | 41 +++++++++++++++++++++++++++++++++-------- 1 file changed, 33 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index 34a8952..dcf2448 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -1302,20 +1302,45 @@ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical, ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0); if (ret < 0) return ret; - ret = btrfs_previous_item(fs_info->extent_root, path, - 0, BTRFS_EXTENT_ITEM_KEY); - if (ret < 0) - return ret; - btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]); + while (1) { + u32 nritems; + if (path->slots[0] == 0) { + btrfs_set_path_blocking(path); + ret = btrfs_prev_leaf(fs_info->extent_root, path); + if (ret != 0) { + if (ret > 0) { + pr_debug("logical %llu is not within " + "any extent\n", logical); + ret = -ENOENT; + } + return ret; + } + } else { + path->slots[0]--; + } + nritems = btrfs_header_nritems(path->nodes[0]); + if (nritems == 0) { + pr_debug("logical %llu is not within any extent\n", + logical); + return -ENOENT; + } + if (path->slots[0] == nritems) + path->slots[0]--; + + btrfs_item_key_to_cpu(path->nodes[0], found_key, + path->slots[0]); + if (found_key->type == BTRFS_EXTENT_ITEM_KEY || + found_key->type == BTRFS_METADATA_ITEM_KEY) + break; + } + if (found_key->type == BTRFS_METADATA_ITEM_KEY) size = fs_info->extent_root->leafsize; else if (found_key->type == BTRFS_EXTENT_ITEM_KEY) size = found_key->offset; - if ((found_key->type != BTRFS_EXTENT_ITEM_KEY && - found_key->type != BTRFS_METADATA_ITEM_KEY) || - found_key->objectid > logical || + if (found_key->objectid > logical || found_key->objectid + size <= logical) { pr_debug("logical %llu is not within any extent\n", logical); return -ENOENT; -- 2.7.4