btrfs: fix unexpected error path when reflinking an inline extent

When reflinking an inline extent, we assert that its file offset is 0 and
that its uncompressed length is not greater than the sector size. We then
return an error if one of those conditions is not satisfied. However we
use a return statement, which results in returning from btrfs_clone()
without freeing the path and buffer that were allocated before, as well as
not clearing the flag BTRFS_INODE_NO_DELALLOC_FLUSH for the destination
inode.

Fix that by jumping to the 'out' label instead, and also add a WARN_ON()
for each condition so that in case assertions are disabled, we get to
known which of the unexpected conditions triggered the error.

Fixes: a61e1e0d ("Btrfs: simplify inline extent handling when doing reflinks")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/reflink.c

@@ -505,8 +505,11 @@ static int btrfs_clone(struct inode *src, struct inode *inode,
 			 */
 			ASSERT(key.offset == 0);
 			ASSERT(datal <= fs_info->sectorsize);
-			if (key.offset != 0 || datal > fs_info->sectorsize)
-				return -EUCLEAN;
+			if (WARN_ON(key.offset != 0) ||
+			    WARN_ON(datal > fs_info->sectorsize)) {
+				ret = -EUCLEAN;
+				goto out;
+			}
 
 			ret = clone_copy_inline_extent(inode, path, &new_key,
 						       drop_start, datal, size,