Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1947512AbbGaVXu (ORCPT ); Fri, 31 Jul 2015 17:23:50 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46781 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932134AbbGaUCt (ORCPT ); Fri, 31 Jul 2015 16:02:49 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Markus Schauler , Omar Sandoval , Chris Mason Subject: [PATCH 4.1 194/267] Btrfs: dont invalidate root dentry when subvolume deletion fails Date: Fri, 31 Jul 2015 12:40:45 -0700 Message-Id: <20150731194008.823533101@linuxfoundation.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <20150731194001.933895871@linuxfoundation.org> References: <20150731194001.933895871@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2506 Lines: 75 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Omar Sandoval commit 64ad6c488975d7516230cf7849190a991fd615ae upstream. Since commit bafc9b754f75 ("vfs: More precise tests in d_invalidate"), mounted subvolumes can be deleted because d_invalidate() won't fail. However, we run into problems when we attempt to delete the default subvolume while it is mounted as the root filesystem: # btrfs subvol list / ID 257 gen 306 top level 5 path rootvol ID 267 gen 334 top level 5 path snap1 # btrfs subvol get-default / ID 267 gen 334 top level 5 path snap1 # btrfs inspect-internal rootid / 267 # mount -o subvol=/ /dev/vda1 /mnt # btrfs subvol del /mnt/snap1 Delete subvolume (no-commit): '/mnt/snap1' ERROR: cannot delete '/mnt/snap1' - Operation not permitted # findmnt / findmnt: can't read /proc/mounts: No such file or directory # ls /proc # Markus reported that this same scenario simply led to a kernel oops. This happens because in btrfs_ioctl_snap_destroy(), we call d_invalidate() before we check may_destroy_subvol(), which means that we detach the submounts and drop the dentry before erroring out. Instead, we should only invalidate the dentry once the deletion has succeeded. Additionally, the shrink_dcache_sb() isn't necessary; d_invalidate() will prune the dcache for the deleted subvolume. Fixes: bafc9b754f75 ("vfs: More precise tests in d_invalidate") Reported-by: Markus Schauler Signed-off-by: Omar Sandoval Signed-off-by: Chris Mason Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/ioctl.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2413,8 +2413,6 @@ static noinline int btrfs_ioctl_snap_des goto out_unlock_inode; } - d_invalidate(dentry); - down_write(&root->fs_info->subvol_sem); err = may_destroy_subvol(dest); @@ -2508,7 +2506,7 @@ out_up_write: out_unlock_inode: mutex_unlock(&inode->i_mutex); if (!err) { - shrink_dcache_sb(root->fs_info->sb); + d_invalidate(dentry); btrfs_invalidate_inodes(dest); d_delete(dentry); ASSERT(dest->send_in_progress == 0); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/