cifs: add mount option to enable local caching

Add a mount option 'fsc' to enable local caching on CIFS.

I considered adding a separate debug bit for caching, but it appears that
debugging would be relatively easier with the normal CIFS_INFO level.

As the cifs-utils (userspace) changes are not done yet, this patch enables
'fsc' by default to enable testing.

Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 6e1fe3a..399b601 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -98,6 +98,7 @@
 	bool noblocksnd:1;
 	bool noautotune:1;
 	bool nostrictsync:1; /* do not force expensive SMBflush on every sync */
+	bool fsc:1;	/* enable fscache */
 	unsigned int rsize;
 	unsigned int wsize;
 	bool sockopt_tcp_nodelay:1;
@@ -843,6 +844,9 @@
 	/* default to using server inode numbers where available */
 	vol->server_ino = 1;
 
+	/* XXX: default to fsc for testing until mount.cifs pieces are done */
+	vol->fsc = 1;
+
 	if (!options)
 		return 1;
 
@@ -1332,6 +1336,8 @@
 			printk(KERN_WARNING "CIFS: Mount option noac not "
 				"supported. Instead set "
 				"/proc/fs/cifs/LookupCacheEnabled to 0\n");
+		} else if (strnicmp(data, "fsc", 3) == 0) {
+			vol->fsc = true;
 		} else
 			printk(KERN_WARNING "CIFS: Unknown mount option %s\n",
 						data);
@@ -2463,6 +2469,8 @@
 		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_OVERR_GID;
 	if (pvolume_info->dynperm)
 		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_DYNPERM;
+	if (pvolume_info->fsc)
+		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_FSCACHE;
 	if (pvolume_info->direct_io) {
 		cFYI(1, "mounting share using direct i/o");
 		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_DIRECT_IO;