From a79a464d5675dbca49d6121425e8eb3571da29f7 Mon Sep 17 00:00:00 2001 From: Misono Tomohiro Date: Wed, 18 Apr 2018 11:35:31 +0900 Subject: [PATCH] btrfs: Allow rmdir(2) to delete an empty subvolume Change the behavior of rmdir(2) and allow it to delete an empty subvolume by using btrfs_delete_subvolume() which is used by btrfs_ioctl_snap_destroy(). This is a change in behaviour and has been requested by users. Deleting the subvolume by ioctl requires root permissions while the rmdir way does works with standard tools and syscalls for all users that can access the subvolume. The main usecase is to allow 'rm -rf /path/with/subvols' to simply work. We were not able to find any nasty usability surprises, the intention is to do the destructive rm. Without allowing rmdir, this would have to be followed by the ioctl subvolume deletion, which is more of an annoyance. Implementation details: The required lock for @dir and inode of @dentry is already acquired in vfs layer. We need some check before deleting a subvolume. Permission check is done in vfs layer, emptiness check is in btrfs_rmdir() and additional check (i.e. neither the subvolume is a default subvolume nor send is in progress) is in btrfs_delete_subvolume(). Note that in btrfs_ioctl_snap_destroy(), d_delete() is called after btrfs_delete_subvolume(). For rmdir(2), d_delete() is called in vfs layer later. Tested-by: Goffredo Baroncelli Signed-off-by: Tomohiro Misono Reviewed-by: David Sterba [ enhance changelog ] Signed-off-by: David Sterba --- fs/btrfs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 6e03e79..d722a30 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4531,7 +4531,7 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry) if (inode->i_size > BTRFS_EMPTY_DIR_SIZE) return -ENOTEMPTY; if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID) - return -EPERM; + return btrfs_delete_subvolume(dir, dentry); trans = __unlink_start_trans(dir); if (IS_ERR(trans)) -- 2.7.4