Btrfs: don't drop path when printing out tree errors in scrub

A user reported a panic where we were panicing somewhere in
tree_backref_for_extent from scrub_print_warning.  He only captured the trace
but looking at scrub_print_warning we drop the path right before we mess with
the extent buffer to print out a bunch of stuff, which isn't right.  So fix this
by dropping the path after we use the eb if we need to.  Thanks,

Cc: stable@vger.kernel.org
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 53c3501fa4ca348f13cb17617b363643a59b1f6f..85e072b956d564d64c527c1b58d3b5b26019c34f 100644 (file)
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -542,7 +542,6 @@ static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
        eb = path->nodes[0];
        ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
        item_size = btrfs_item_size_nr(eb, path->slots[0]);
-       btrfs_release_path(path);
 
        if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
                do {
@@ -558,7 +557,9 @@ static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
                                ret < 0 ? -1 : ref_level,
                                ret < 0 ? -1 : ref_root);
                } while (ret != 1);
+               btrfs_release_path(path);
        } else {
+               btrfs_release_path(path);
                swarn.path = path;
                swarn.dev = dev;
                iterate_extent_inodes(fs_info, found_key.objectid,