cifs: add shutdown support

Various filesystem support the shutdown ioctl which is used by various
xfstests. The shutdown ioctl sets a flag on the superblock which
prevents open, unlink, symlink, hardlink, rmdir, create etc.
on the file system until unmount and remounted. The two flags supported
in this patch are:

  FSOP_GOING_FLAGS_LOGFLUSH and FSOP_GOING_FLAGS_NOLOGFLUSH

which require very little other than blocking new operations (since
we do not cache writes to metadata on the client with cifs.ko).
FSOP_GOING_FLAGS_DEFAULT is not supported yet, but could be added in
the future but would need to call syncfs or equivalent to write out
pending data on the mount.

With this patch various xfstests now work including tests 043 through
046 for example.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/fs/cifs/cifs_ioctl.h b/fs/cifs/cifs_ioctl.h
index 153d5c842a9b..f262c64516bc 100644
--- a/fs/cifs/cifs_ioctl.h
+++ b/fs/cifs/cifs_ioctl.h
@@ -78,3 +78,19 @@ struct smb3_notify {
 #define CIFS_QUERY_INFO _IOWR(CIFS_IOCTL_MAGIC, 7, struct smb_query_info)
 #define CIFS_DUMP_KEY _IOWR(CIFS_IOCTL_MAGIC, 8, struct smb3_key_debug_info)
 #define CIFS_IOC_NOTIFY _IOW(CIFS_IOCTL_MAGIC, 9, struct smb3_notify)
+#define CIFS_IOC_SHUTDOWN _IOR ('X', 125, __u32)
+
+/*
+ * Flags for going down operation
+ */
+#define CIFS_GOING_FLAGS_DEFAULT                0x0     /* going down */
+#define CIFS_GOING_FLAGS_LOGFLUSH               0x1     /* flush log but not data */
+#define CIFS_GOING_FLAGS_NOLOGFLUSH             0x2     /* don't flush log nor data */
+
+static inline bool cifs_forced_shutdown(struct cifs_sb_info *sbi)
+{
+	if (CIFS_MOUNT_SHUTDOWN & sbi->mnt_cifs_flags)
+		return true;
+	else
+		return false;
+}