4 files changed, 48 insertions, 6 deletions

diff --git a/fs/filesystems.c b/fs/filesystems.c
index 7a4f61aa05f8..f37f87262837 100644
--- a/fs/filesystems.c
+++ b/fs/filesystems.c
@@ -41,11 +41,12 @@ void put_filesystem(struct file_system_type *fs)
         module_put(fs->owner);
 }
 
-static struct file_system_type **find_filesystem(const char *name)
+static struct file_system_type **find_filesystem(const char *name, unsigned len)
 {
         struct file_system_type **p;
         for (p=&file_systems; *p; p=&(*p)->next)
-                if (strcmp((*p)->name,name) == 0)
+                if (strlen((*p)->name) == len &&
+                    strncmp((*p)->name, name, len) == 0)
                         break;
         return p;
 }
@@ -68,11 +69,12 @@ int register_filesystem(struct file_system_type * fs)
         int res = 0;
         struct file_system_type ** p;
 
+        BUG_ON(strchr(fs->name, '.'));
         if (fs->next)
                 return -EBUSY;
         INIT_LIST_HEAD(&fs->fs_supers);
         write_lock(&file_systems_lock);
-        p = find_filesystem(fs->name);
+        p = find_filesystem(fs->name, strlen(fs->name));
         if (*p)
                 res = -EBUSY;
         else
@@ -215,19 +217,26 @@ int get_filesystem_list(char * buf)
 struct file_system_type *get_fs_type(const char *name)
 {
         struct file_system_type *fs;
+        const char *dot = strchr(name, '.');
+        unsigned len = dot ? dot - name : strlen(name);
 
         read_lock(&file_systems_lock);
-        fs = *(find_filesystem(name));
+        fs = *(find_filesystem(name, len));
         if (fs && !try_module_get(fs->owner))
                 fs = NULL;
         read_unlock(&file_systems_lock);
-        if (!fs && (request_module("%s", name) == 0)) {
+        if (!fs && (request_module("%.*s", len, name) == 0)) {
                 read_lock(&file_systems_lock);
-                fs = *(find_filesystem(name));
+                fs = *(find_filesystem(name, len));
                 if (fs && !try_module_get(fs->owner))
                         fs = NULL;
                 read_unlock(&file_systems_lock);
         }
+
+        if (dot && fs && !(fs->fs_flags & FS_HAS_SUBTYPE)) {
+                put_filesystem(fs);
+                fs = NULL;
+        }
         return fs;
 }
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index d8003be56e05..1397018ff476 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -636,6 +636,7 @@ static int fuse_get_sb(struct file_system_type *fs_type,
 static struct file_system_type fuse_fs_type = {
         .owner          = THIS_MODULE,
         .name           = "fuse",
+        .fs_flags       = FS_HAS_SUBTYPE,
         .get_sb         = fuse_get_sb,
         .kill_sb        = kill_anon_super,
 };
@@ -652,6 +653,7 @@ static int fuse_get_sb_blk(struct file_system_type *fs_type,
 static struct file_system_type fuseblk_fs_type = {
         .owner          = THIS_MODULE,
         .name           = "fuseblk",
+        .fs_flags       = FS_HAS_SUBTYPE,
         .get_sb         = fuse_get_sb_blk,
         .kill_sb        = kill_block_super,
         .fs_flags       = FS_REQUIRES_DEV,
diff --git a/fs/namespace.c b/fs/namespace.c
index be5e56bfb73e..c5b88100d914 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -377,6 +377,10 @@ static int show_vfsmnt(struct seq_file *m, void *v)
         seq_path(m, mnt, mnt->mnt_root, " \t\n\\");
         seq_putc(m, ' ');
         mangle(m, mnt->mnt_sb->s_type->name);
+        if (mnt->mnt_sb->s_subtype && mnt->mnt_sb->s_subtype[0]) {
+                seq_putc(m, '.');
+                mangle(m, mnt->mnt_sb->s_subtype);
+        }
         seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw");
         for (fs_infop = fs_info; fs_infop->flag; fs_infop++) {
                 if (mnt->mnt_sb->s_flags & fs_infop->flag)
diff --git a/fs/super.c b/fs/super.c
index 8341e4e1d738..5260d620c555 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -107,6 +107,7 @@ out:
 static inline void destroy_super(struct super_block *s)
 {
         security_sb_free(s);
+        kfree(s->s_subtype);
         kfree(s);
 }
 
@@ -907,6 +908,29 @@ out:
 
 EXPORT_SYMBOL_GPL(vfs_kern_mount);
 
+static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
+{
+        int err;
+        const char *subtype = strchr(fstype, '.');
+        if (subtype) {
+                subtype++;
+                err = -EINVAL;
+                if (!subtype[0])
+                        goto err;
+        } else
+                subtype = "";
+
+        mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
+        err = -ENOMEM;
+        if (!mnt->mnt_sb->s_subtype)
+                goto err;
+        return mnt;
+
+ err:
+        mntput(mnt);
+        return ERR_PTR(err);
+}
+
 struct vfsmount *
 do_kern_mount(const char *fstype, int flags, const char *name, void *data)
 {
@@ -915,6 +939,9 @@ do_kern_mount(const char *fstype, int flags, const char *name, void *data)
         if (!type)
                 return ERR_PTR(-ENODEV);
         mnt = vfs_kern_mount(type, flags, name, data);
+        if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
+            !mnt->mnt_sb->s_subtype)
+                mnt = fs_set_subtype(mnt, fstype);
         put_filesystem(type);
         return mnt;
 }