On Wed, Oct 31, 2018 at 10:06:08AM -0700, Omar Sandoval wrote: > From: Omar Sandoval <[email protected]> > > There's a race between close_ctree() and cleaner_kthread(). > close_ctree() sets btrfs_fs_closing(), and the cleaner stops when it > sees it set, but this is racy; the cleaner might have already checked > the bit and could be cleaning stuff. In particular, if it deletes unused > block groups, it will create delayed iputs for the free space cache > inodes. As of "btrfs: don't run delayed_iputs in commit", we're no > longer running delayed iputs after a commit. Therefore, if the cleaner > creates more delayed iputs after delayed iputs are run in > btrfs_commit_super(), we will leak inodes on unmount and get a busy > inode crash from the VFS. > > Fix it by parking the cleaner before we actually close anything. Then, > any remaining delayed iputs will always be handled in > btrfs_commit_super(). This also ensures that the commit in close_ctree() > is really the last commit, so we can get rid of the commit in > cleaner_kthread(). > > Fixes: 30928e9baac2 ("btrfs: don't run delayed_iputs in commit") > Signed-off-by: Omar Sandoval <[email protected]>
I'll queue this patch for rc2 as it fixes crashes I see during testing. My version does more changes and would be more suitable for a series, that could actually document the shutdown sequence and add a few assertions on top. Reviewed-by: David Sterba <[email protected]>
