CIFS: Force revalidate inode when dentry is stale

commit c82e5ac7 upstream.

Currently the client indicates that a dentry is stale when inode
numbers or type types between a local inode and a remote file
don't match. If this is the case attributes is not being copied
from remote to local, so, it is already known that the local copy
has stale metadata. That's why the inode needs to be marked for
revalidation in order to tell the VFS to lookup the dentry again
before openning a file. This prevents unexpected stale errors
to be returned to the user space when openning a file.

Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/cifs/inode.c

@@ -410,6 +410,7 @@ int cifs_get_inode_info_unix(struct inode **pinode,
 		/* if uniqueid is different, return error */
 		if (unlikely(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM &&
 		    CIFS_I(*pinode)->uniqueid != fattr.cf_uniqueid)) {
+			CIFS_I(*pinode)->time = 0; /* force reval */
 			rc = -ESTALE;
 			goto cgiiu_exit;
 		}
@@ -417,6 +418,7 @@ int cifs_get_inode_info_unix(struct inode **pinode,
 		/* if filetype is different, return error */
 		if (unlikely(((*pinode)->i_mode & S_IFMT) !=
 		    (fattr.cf_mode & S_IFMT))) {
+			CIFS_I(*pinode)->time = 0; /* force reval */
 			rc = -ESTALE;
 			goto cgiiu_exit;
 		}
@@ -926,6 +928,7 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
 		/* if uniqueid is different, return error */
 		if (unlikely(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM &&
 		    CIFS_I(*inode)->uniqueid != fattr.cf_uniqueid)) {
+			CIFS_I(*inode)->time = 0; /* force reval */
 			rc = -ESTALE;
 			goto cgii_exit;
 		}
@@ -933,6 +936,7 @@ cifs_get_inode_info(struct inode **inode, const char *full_path,
 		/* if filetype is different, return error */
 		if (unlikely(((*inode)->i_mode & S_IFMT) !=
 		    (fattr.cf_mode & S_IFMT))) {
+			CIFS_I(*inode)->time = 0; /* force reval */
 			rc = -ESTALE;
 			goto cgii_exit;
 		}