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, 7 insertions, 0 deletions

diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 616e1bc0cc0a..1cbe7ec73728 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -30,6 +30,7 @@
 #include "cifs_fs_sb.h"
 #include "cifs_unicode.h"
 #include "smb2proto.h"
+#include "cifs_ioctl.h"
 
 /*
  * M-F Symlink Functions - Begin
@@ -518,6 +519,9 @@ cifs_hardlink(struct dentry *old_file, struct inode *inode,
 	struct TCP_Server_Info *server;
 	struct cifsInodeInfo *cifsInode;
 
+	if (unlikely(cifs_forced_shutdown(cifs_sb)))
+		return -EIO;
+
 	tlink = cifs_sb_tlink(cifs_sb);
 	if (IS_ERR(tlink))
 		return PTR_ERR(tlink);
@@ -682,6 +686,9 @@ cifs_symlink(struct user_namespace *mnt_userns, struct inode *inode,
 	void *page = alloc_dentry_path();
 	struct inode *newinode = NULL;
 
+	if (unlikely(cifs_forced_shutdown(cifs_sb)))
+		return -EIO;
+
 	xid = get_xid();
 
 	tlink = cifs_sb_tlink(cifs_sb);