Btrfs: cleanup BUG_ON in merge_bio
One can use btrfs-corrupt-block to hit BUG_ON() in merge_bio(),
thus this aims to stop anyone to panic the whole system by using
their btrfs.
Since the error in merge_bio can only come from __btrfs_map_block()
when chunk tree mapping has something insane and __btrfs_map_block()
has already had printed the reason, we can just return errors in
merge_bio.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 01c6fca..f935fad 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1822,6 +1822,10 @@
/*
* extent_io.c merge_bio_hook, this must check the chunk tree to make sure
* we don't create bios that span stripes or chunks
+ *
+ * return 1 if page cannot be merged to bio
+ * return 0 if page can be merged to bio
+ * return error otherwise
*/
int btrfs_merge_bio_hook(int rw, struct page *page, unsigned long offset,
size_t size, struct bio *bio,
@@ -1840,8 +1844,8 @@
map_length = length;
ret = btrfs_map_block(root->fs_info, rw, logical,
&map_length, NULL, 0);
- /* Will always return 0 with map_multi == NULL */
- BUG_ON(ret < 0);
+ if (ret < 0)
+ return ret;
if (map_length < length + size)
return 1;
return 0;