1 files changed, 38 insertions, 5 deletions

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 064e69d2fdde..1b555cd41e3b 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -100,6 +100,7 @@ enum {
         Opt_udp, Opt_tcp,
         Opt_acl, Opt_noacl,
         Opt_rdirplus, Opt_nordirplus,
+        Opt_sharecache, Opt_nosharecache,
 
         /* Mount options that take integer arguments */
         Opt_port,
@@ -146,6 +147,8 @@ static match_table_t nfs_mount_option_tokens = {
         { Opt_noacl, "noacl" },
         { Opt_rdirplus, "rdirplus" },
         { Opt_nordirplus, "nordirplus" },
+        { Opt_sharecache, "sharecache" },
+        { Opt_nosharecache, "nosharecache" },
 
         { Opt_port, "port=%u" },
         { Opt_rsize, "rsize=%u" },
@@ -450,6 +453,7 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
                 { NFS_MOUNT_NONLM, ",nolock", "" },
                 { NFS_MOUNT_NOACL, ",noacl", "" },
                 { NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" },
+                { NFS_MOUNT_UNSHARED, ",nosharecache", ""},
                 { 0, NULL, NULL }
         };
         const struct proc_nfs_info *nfs_infop;
@@ -714,6 +718,12 @@ static int nfs_parse_mount_options(char *raw,
                 case Opt_nordirplus:
                         mnt->flags |= NFS_MOUNT_NORDIRPLUS;
                         break;
+                case Opt_sharecache:
+                        mnt->flags &= ~NFS_MOUNT_UNSHARED;
+                        break;
+                case Opt_nosharecache:
+                        mnt->flags |= NFS_MOUNT_UNSHARED;
+                        break;
 
                 case Opt_port:
                         if (match_int(args, &option))
@@ -1309,6 +1319,9 @@ static int nfs_compare_super(struct super_block *sb, void *data)
 
         if (old->nfs_client != server->nfs_client)
                 return 0;
+        /* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */
+        if (old->flags & NFS_MOUNT_UNSHARED)
+                return 0;
         if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)
                 return 0;
         return 1;
@@ -1322,6 +1335,7 @@ static int nfs_get_sb(struct file_system_type *fs_type,
         struct nfs_fh mntfh;
         struct nfs_mount_data *data = raw_data;
         struct dentry *mntroot;
+        int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
         int error;
 
         /* Validate the mount data */
@@ -1336,8 +1350,11 @@ static int nfs_get_sb(struct file_system_type *fs_type,
                 goto out;
         }
 
+        if (server->flags & NFS_MOUNT_UNSHARED)
+                compare_super = NULL;
+
         /* Get a superblock - note that we may end up sharing one that already exists */
-        s = sget(fs_type, nfs_compare_super, nfs_set_super, server);
+        s = sget(fs_type, compare_super, nfs_set_super, server);
         if (IS_ERR(s)) {
                 error = PTR_ERR(s);
                 goto out_err_nosb;
@@ -1402,6 +1419,7 @@ static int nfs_xdev_get_sb(struct file_system_type *fs_type, int flags,
         struct super_block *s;
         struct nfs_server *server;
         struct dentry *mntroot;
+        int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
         int error;
 
         dprintk("--> nfs_xdev_get_sb()\n");
@@ -1413,8 +1431,11 @@ static int nfs_xdev_get_sb(struct file_system_type *fs_type, int flags,
                 goto out_err_noserver;
         }
 
+        if (server->flags & NFS_MOUNT_UNSHARED)
+                compare_super = NULL;
+
         /* Get a superblock - note that we may end up sharing one that already exists */
-        s = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, server);
+        s = sget(&nfs_fs_type, compare_super, nfs_set_super, server);
         if (IS_ERR(s)) {
                 error = PTR_ERR(s);
                 goto out_err_nosb;
@@ -1657,6 +1678,7 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
         struct nfs_fh mntfh;
         struct dentry *mntroot;
         char *mntpath = NULL, *hostname = NULL, *ip_addr = NULL;
+        int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
         int error;
 
         /* Validate the mount data */
@@ -1673,8 +1695,11 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
                 goto out;
         }
 
+        if (server->flags & NFS4_MOUNT_UNSHARED)
+                compare_super = NULL;
+
         /* Get a superblock - note that we may end up sharing one that already exists */
-        s = sget(fs_type, nfs_compare_super, nfs_set_super, server);
+        s = sget(fs_type, compare_super, nfs_set_super, server);
         if (IS_ERR(s)) {
                 error = PTR_ERR(s);
                 goto out_free;
@@ -1740,6 +1765,7 @@ static int nfs4_xdev_get_sb(struct file_system_type *fs_type, int flags,
         struct super_block *s;
         struct nfs_server *server;
         struct dentry *mntroot;
+        int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
         int error;
 
         dprintk("--> nfs4_xdev_get_sb()\n");
@@ -1751,8 +1777,11 @@ static int nfs4_xdev_get_sb(struct file_system_type *fs_type, int flags,
                 goto out_err_noserver;
         }
 
+        if (server->flags & NFS4_MOUNT_UNSHARED)
+                compare_super = NULL;
+
         /* Get a superblock - note that we may end up sharing one that already exists */
-        s = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, server);
+        s = sget(&nfs_fs_type, compare_super, nfs_set_super, server);
         if (IS_ERR(s)) {
                 error = PTR_ERR(s);
                 goto out_err_nosb;
@@ -1807,6 +1836,7 @@ static int nfs4_referral_get_sb(struct file_system_type *fs_type, int flags,
         struct nfs_server *server;
         struct dentry *mntroot;
         struct nfs_fh mntfh;
+        int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
         int error;
 
         dprintk("--> nfs4_referral_get_sb()\n");
@@ -1818,8 +1848,11 @@ static int nfs4_referral_get_sb(struct file_system_type *fs_type, int flags,
                 goto out_err_noserver;
         }
 
+        if (server->flags & NFS4_MOUNT_UNSHARED)
+                compare_super = NULL;
+
         /* Get a superblock - note that we may end up sharing one that already exists */
-        s = sget(&nfs_fs_type, nfs_compare_super, nfs_set_super, server);
+        s = sget(&nfs_fs_type, compare_super, nfs_set_super, server);
         if (IS_ERR(s)) {
                 error = PTR_ERR(s);
                 goto out_err_nosb;