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>

2 files changed, 9 insertions, 0 deletions

diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
index 246a167cb913..9e771450c3b8 100644
--- a/fs/cifs/cifs_fs_sb.h
+++ b/fs/cifs/cifs_fs_sb.h
@@ -35,6 +35,7 @@
 #define CIFS_MOUNT_DYNPERM      0x1000 /* allow in-memory only mode setting   */
 #define CIFS_MOUNT_NOPOSIXBRL   0x2000 /* mandatory not posix byte range lock */
 #define CIFS_MOUNT_NOSSYNC      0x4000 /* don't do slow SMBflush on every sync*/
+#define CIFS_MOUNT_FSCACHE      0x8000 /* local caching enabled */
 
 struct cifs_sb_info {
         struct cifsTconInfo *tcon;      /* primary mount */
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 6e1fe3a7f27d..399b60129b74 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -98,6 +98,7 @@ struct smb_vol {
         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 @@ cifs_parse_mount_options(char *options, const char *devname,
         /* 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 @@ cifs_parse_mount_options(char *options, const char *devname,
                         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 @@ static void setup_cifs_sb(struct smb_vol *pvolume_info,
                 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;