NFS: Add mount options for controlling the lookup cache

Add the following NFS-specific mount options to the parser.

    -o lookupcache=all          /* Default: cache positive & negative
                                   dentries */
    -o lookupcache=pos[itive]   /* Don't cache negative dentries */
    -o lookupcache=none         /* Strict revalidation of all dentries */

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 81686aeb1b5d..1e3558697219 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -91,6 +91,7 @@ enum {
         /* Mount options that take string arguments */
         Opt_sec, Opt_proto, Opt_mountproto, Opt_mounthost,
         Opt_addr, Opt_mountaddr, Opt_clientaddr,
+        Opt_lookupcache,
 
         /* Special mount options */
         Opt_userspace, Opt_deprecated, Opt_sloppy,
@@ -154,6 +155,8 @@ static match_table_t nfs_mount_option_tokens = {
         { Opt_mounthost, "mounthost=%s" },
         { Opt_mountaddr, "mountaddr=%s" },
 
+        { Opt_lookupcache, "lookupcache=%s" },
+
         { Opt_err, NULL }
 };
 
@@ -200,6 +203,22 @@ static match_table_t nfs_secflavor_tokens = {
         { Opt_sec_err, NULL }
 };
 
+enum {
+        Opt_lookupcache_all, Opt_lookupcache_positive,
+        Opt_lookupcache_none,
+
+        Opt_lookupcache_err
+};
+
+static match_table_t nfs_lookupcache_tokens = {
+        { Opt_lookupcache_all, "all" },
+        { Opt_lookupcache_positive, "pos" },
+        { Opt_lookupcache_positive, "positive" },
+        { Opt_lookupcache_none, "none" },
+
+        { Opt_lookupcache_err, NULL }
+};
+
 
 static void nfs_umount_begin(struct super_block *);
 static int  nfs_statfs(struct dentry *, struct kstatfs *);
@@ -1250,6 +1269,30 @@ static int nfs_parse_mount_options(char *raw,
                                              &mnt->mount_server.addrlen);
                         kfree(string);
                         break;
+                case Opt_lookupcache:
+                        string = match_strdup(args);
+                        if (string == NULL)
+                                goto out_nomem;
+                        token = match_token(string,
+                                        nfs_lookupcache_tokens, args);
+                        kfree(string);
+                        switch (token) {
+                                case Opt_lookupcache_all:
+                                        mnt->flags &= ~(NFS_MOUNT_LOOKUP_CACHE_NONEG|NFS_MOUNT_LOOKUP_CACHE_NONE);
+                                        break;
+                                case Opt_lookupcache_positive:
+                                        mnt->flags &= ~NFS_MOUNT_LOOKUP_CACHE_NONE;
+                                        mnt->flags |= NFS_MOUNT_LOOKUP_CACHE_NONEG;
+                                        break;
+                                case Opt_lookupcache_none:
+                                        mnt->flags |= NFS_MOUNT_LOOKUP_CACHE_NONEG|NFS_MOUNT_LOOKUP_CACHE_NONE;
+                                        break;
+                                default:
+                                        errors++;
+                                        dfprintk(MOUNT, "NFS:   invalid "
+                                                        "lookupcache argument\n");
+                        };
+                        break;
 
                 /*
                  * Special options