Btrfs: Improve and cleanup locking done by walk_down_tree

Browse source

While dropping snapshots, walk_down_tree does most of the work of checking
reference counts and limiting tree traversal to just the blocks that
we are freeing.

It dropped and held the allocation mutex in strange and confusing ways,
this commit changes it to only hold the mutex while actually freeing a block.

The rest of the checks around reference counts should be safe without the lock
because we only allow one process in btrfs_drop_snapshot at a time.  Other
processes dropping reference counts should not drop it to 1 because
their tree roots already have an extra ref on the block.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

...

This commit is contained in:

Chris Mason 2008-08-01 11:27:23 -04:00

parent 492bb6deee

commit f87f057b49

3 changed files with 70 additions and 34 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

85

fs/btrfs/extent-tree.c

View file

13

fs/btrfs/file.c

View file

6

fs/btrfs/ioctl.c

View file