btrfs: assert that extent buffers are write locked instead of only locked

We currently use lockdep_assert_held() at btrfs_assert_tree_locked(), and
that checks that we hold a lock either in read mode or write mode.

However in all contexts we use btrfs_assert_tree_locked(), we actually
want to check if we are holding a write lock on the extent buffer's rw
semaphore - it would be a bug if in any of those contexts we were holding
a read lock instead.

So change btrfs_assert_tree_locked() to use lockdep_assert_held_write()
instead and, to make it more explicit, rename btrfs_assert_tree_locked()
to btrfs_assert_tree_write_locked(), so that it's clear we want to check
we are holding a write lock.

For now there are no contexts where we want to assert that we must have
a read lock, but in case that is needed in the future, we can add a new
helper function that just calls out lockdep_assert_held_read().

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 8a4514283a4b..2837b4c8424d 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -138,7 +138,7 @@ int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode,
 		 * matches our target xattr, so lets check.
 		 */
 		ret = 0;
-		btrfs_assert_tree_locked(path->nodes[0]);
+		btrfs_assert_tree_write_locked(path->nodes[0]);
 		di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
 		if (!di && !(flags & XATTR_REPLACE)) {
 			ret = -ENOSPC;