Btrfs: handle a bogus chunk tree nicely
If you restore a btrfs-image file system and try to mount that file system we'll
panic. That's because btrfs-image restores and just makes one big chunk to
envelope the whole disk, since they are really only meant to be messed with by
our btrfs-progs. So fix up btrfs_rmap_block and the callers of it for mount so
that we no longer panic but instead just return an error and fail to mount.
Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 5989a92..2854c82 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4935,7 +4935,18 @@
em = lookup_extent_mapping(em_tree, chunk_start, 1);
read_unlock(&em_tree->lock);
- BUG_ON(!em || em->start != chunk_start);
+ if (!em) {
+ printk(KERN_ERR "btrfs: couldn't find em for chunk %Lu\n",
+ chunk_start);
+ return -EIO;
+ }
+
+ if (em->start != chunk_start) {
+ printk(KERN_ERR "btrfs: bad chunk start, em=%Lu, wanted=%Lu\n",
+ em->start, chunk_start);
+ free_extent_map(em);
+ return -EIO;
+ }
map = (struct map_lookup *)em->bdev;
length = em->len;