CAPI: Pin capifs instead of mounting it

Auto-mounting the capifs during module init prevents unloading its
module. Instead, pin the filesystem as long as some NCCI node exists.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 9 deletions

diff --git a/drivers/isdn/capi/capifs.c b/drivers/isdn/capi/capifs.c
index 6ae0edf29c85..51c01efe2fe4 100644
--- a/drivers/isdn/capi/capifs.c
+++ b/drivers/isdn/capi/capifs.c
@@ -32,6 +32,7 @@ static char *revision = "$Revision: 1.1.2.3 $";
 #define CAPIFS_SUPER_MAGIC (('C'<<8)|'N')
 
 static struct vfsmount *capifs_mnt;
+static int capifs_mnt_count;
 
 static struct {
         int setuid;
@@ -140,7 +141,7 @@ static struct file_system_type capifs_fs_type = {
         .kill_sb        = kill_anon_super,
 };
 
-struct dentry *capifs_new_ncci(unsigned int number, dev_t device)
+static struct dentry *new_ncci(unsigned int number, dev_t device)
 {
         struct super_block *s = capifs_mnt->mnt_sb;
         struct dentry *root = s->s_root;
@@ -187,6 +188,20 @@ unlock_out:
         return dentry;
 }
 
+struct dentry *capifs_new_ncci(unsigned int number, dev_t device)
+{
+        struct dentry *dentry;
+
+        if (simple_pin_fs(&capifs_fs_type, &capifs_mnt, &capifs_mnt_count) < 0)
+                return NULL;
+
+        dentry = new_ncci(number, device);
+        if (!dentry)
+                simple_release_fs(&capifs_mnt, &capifs_mnt_count);
+
+        return dentry;
+}
+
 void capifs_free_ncci(struct dentry *dentry)
 {
         struct dentry *root = capifs_mnt->mnt_sb->s_root;
@@ -206,6 +221,8 @@ void capifs_free_ncci(struct dentry *dentry)
         dput(dentry);
 
         mutex_unlock(&root->d_inode->i_mutex);
+
+        simple_release_fs(&capifs_mnt, &capifs_mnt_count);
 }
 
 static int __init capifs_init(void)
@@ -222,13 +239,6 @@ static int __init capifs_init(void)
                 strcpy(rev, "1.0");
 
         err = register_filesystem(&capifs_fs_type);
-        if (!err) {
-                capifs_mnt = kern_mount(&capifs_fs_type);
-                if (IS_ERR(capifs_mnt)) {
-                        err = PTR_ERR(capifs_mnt);
-                        unregister_filesystem(&capifs_fs_type);
-                }
-        }
         if (!err)
                 printk(KERN_NOTICE "capifs: Rev %s\n", rev);
         return err;
@@ -237,7 +247,6 @@ static int __init capifs_init(void)
 static void __exit capifs_exit(void)
 {
         unregister_filesystem(&capifs_fs_type);
-        mntput(capifs_mnt);
 }
 
 EXPORT_SYMBOL(capifs_new_ncci);