Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 6dddcbeb authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Use mutex_lock_nested for tree locking 



Lockdep has the notion of locking subclasses so that you can identify
locks you expect to be taken after other locks of the same class.  This
changes the per-extent buffer btree locking routines to use a subclass based
on the level in the tree.

Unfortunately, lockdep can only handle 8 total subclasses, and the btrfs
max level is also 8.  So when lockdep is on, use a lower max level.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent f421950f

fs/btrfs/ctree.h

+5 −1
Original line number Diff line number Diff line
@@ -42,7 +42,11 @@ struct btrfs_ordered_sum; 


#define BTRFS_MAGIC "_B5RfS_M"



#ifdef CONFIG_LOCKDEP

# define BTRFS_MAX_LEVEL 7

#else

# define BTRFS_MAX_LEVEL 8

#endif



/* holds pointers to all of the tree roots */

#define BTRFS_ROOT_TREE_OBJECTID 1ULL

fs/btrfs/locking.c

+1 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ int btrfs_tree_lock(struct extent_buffer *eb) 
			return 0;

	}

	cpu_relax();

	mutex_lock(&eb->mutex);

	mutex_lock_nested(&eb->mutex, BTRFS_MAX_LEVEL - btrfs_header_level(eb));

	return 0;

}