Before commit bafc9b754f75 ("vfs: More precise tests in d_invalidate"),
d_invalidate() could return -EBUSY when a dentry for a directory had
more than one reference to it. This is what prevented a mounted
subvolume from being deleted, as struct vfsmount holds a reference to
the subvolume dentry. However, that commit removed that case, and later
commits in that patch series removed the return code from d_invalidate()
completely, so we don't get that check for free anymore. So, reintroduce
it in btrfs_ioctl_snap_destroy().Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=93021 Reported-by: Timo Kokkonen <[email protected]> Fixes: bafc9b754f75 ("vfs: More precise tests in d_invalidate") Signed-off-by: Omar Sandoval <[email protected]> --- This applies to 4.0-rc6. To be honest, I'm not sure that this is the most correct fix for this bug, but it's equivalent to the pre-3.18 behavior and it's the best that I could come up with. Thoughts? fs/btrfs/ioctl.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 74609b9..39b0538 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2384,6 +2384,12 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file, goto out_dput; } + spin_lock(&dentry->d_lock); + err = dentry->d_lockref.count > 1 ? -EBUSY : 0; + spin_unlock(&dentry->d_lock); + if (err) + goto out_dput; + mutex_lock(&inode->i_mutex); /* -- 2.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
