A user reported that fsck was complaining about unresolved refs for some
snapshots. You can reproduce this by doing
mkfs.btrfs /dev/sdb
mount /dev/sdb /mnt
btrfs subvol snap /mnt/ /mnt/a
btrfs subvol snap /mnt/ /mnt/b
btrfs subvol del /mnt/a
umount /mnt
btrfsck /dev/sdb
and you'd get this
unresolved ref root 258 dir 256 index 2 namelen 1 name a error 600
because snapshot b has a dir item that points to a. Except we encode in our
root ref the dirid of the ref holder, and if it doesn't match we just give it
back a empty directory since we can't hardlink directories. This makes the
check in btrfsck bogus, when we delete a we remove the ref key for it so any
lookups into /mnt/b/a will just give a blank directory as it's supposed to. Fix
this by only saying the backref is reachable if there is both a DIR_ITEM and a
REF_KEY for the given root. With this patch I no longer see errors when running
this reproducer. Thanks,
Signed-off-by: Josef Bacik <jba...@fusionio.com>
---
cmds-check.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/cmds-check.c b/cmds-check.c
index bbef89a..4083298 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -1507,14 +1507,16 @@ static int add_root_backref(struct cache_tree
*root_cache,
}
if (item_type == BTRFS_DIR_ITEM_KEY) {
+ if (backref->found_forward_ref)
+ rec->found_ref++;
backref->found_dir_item = 1;
- backref->reachable = 1;
- rec->found_ref++;
} else if (item_type == BTRFS_DIR_INDEX_KEY) {
backref->found_dir_index = 1;
} else if (item_type == BTRFS_ROOT_REF_KEY) {
if (backref->found_forward_ref)
backref->errors |= REF_ERR_DUP_ROOT_REF;
+ else if (backref->found_dir_item)
+ rec->found_ref++;
backref->found_forward_ref = 1;
} else if (item_type == BTRFS_ROOT_BACKREF_KEY) {
if (backref->found_back_ref)
@@ -1524,6 +1526,8 @@ static int add_root_backref(struct cache_tree *root_cache,
BUG_ON(1);
}
+ if (backref->found_forward_ref && backref->found_dir_item)
+ backref->reachable = 1;
return 0;
}
--
1.7.7.6
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