orangefs: free superblock when mount fails

Otherwise lockdep says:

[ 1337.483798] ================================================
[ 1337.483999] [ BUG: lock held when returning to user space! ]
[ 1337.484252] 4.11.0-rc6 #19 Not tainted
[ 1337.484423] ------------------------------------------------
[ 1337.484626] mount/14766 is leaving the kernel with locks still held!
[ 1337.484841] 1 lock held by mount/14766:
[ 1337.485017]  #0:  (&type->s_umount_key#33/1){+.+.+.}, at: [<ffffffff8124171f>] sget_userns+0x2af/0x520

Caught by xfstests generic/413 which tried to mount with the unsupported
mount option dax.  Then xfstests generic/422 ran sync which deadlocks.

Signed-off-by: Martin Brandenburg <martin@omnibond.com>
Acked-by: Mike Marshall <hubcap@omnibond.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/orangefs/devorangefs-req.c b/fs/orangefs/devorangefs-req.c
index c4ab6fdf17a0..e1534c9bab16 100644
--- a/fs/orangefs/devorangefs-req.c
+++ b/fs/orangefs/devorangefs-req.c
@@ -208,14 +208,19 @@ restart:
                                 continue;
                         /*
                          * Skip ops whose filesystem we don't know about unless
-                         * it is being mounted.
+                         * it is being mounted or unmounted.  It is possible for
+                         * a filesystem we don't know about to be unmounted if
+                         * it fails to mount in the kernel after userspace has
+                         * been sent the mount request.
                          */
                         /* XXX: is there a better way to detect this? */
                         } else if (ret == -1 &&
                                    !(op->upcall.type ==
                                         ORANGEFS_VFS_OP_FS_MOUNT ||
                                      op->upcall.type ==
-                                        ORANGEFS_VFS_OP_GETATTR)) {
+                                        ORANGEFS_VFS_OP_GETATTR ||
+                                     op->upcall.type ==
+                                        ORANGEFS_VFS_OP_FS_UMOUNT)) {
                                 gossip_debug(GOSSIP_DEV_DEBUG,
                                     "orangefs: skipping op tag %llu %s\n",
                                     llu(op->tag), get_opname_string(op));