Fix the race between capifs remount and node creation

we don't want to deal with half-updated config

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/drivers/isdn/capi/capifs.c b/drivers/isdn/capi/capifs.c
index 8f9f3b5..bff72d8 100644 (file)
--- a/drivers/isdn/capi/capifs.c
+++ b/drivers/isdn/capi/capifs.c
@@ -75,14 +75,17 @@ static int capifs_remount(struct super_block *s, int *flags, char *data)
                }
        }
 
-       replace_mount_options(s, new_opt);
+       mutex_lock(&s->s_root->d_inode->i_mutex);
 
+       replace_mount_options(s, new_opt);
        config.setuid  = setuid;
        config.setgid  = setgid;
        config.uid     = uid;
        config.gid     = gid;
        config.mode    = mode;
 
+       mutex_unlock(&s->s_root->d_inode->i_mutex);
+
        return 0;
 }
 
@@ -153,13 +156,16 @@ void capifs_new_ncci(unsigned int number, dev_t device)
        if (!inode)
                return;
        inode->i_ino = number+2;
+
+       dentry = get_node(number);
+
+       /* config contents is protected by root's i_mutex */
        inode->i_uid = config.setuid ? config.uid : current_fsuid();
        inode->i_gid = config.setgid ? config.gid : current_fsgid();
        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
        init_special_inode(inode, S_IFCHR|config.mode, device);
        //inode->i_op = &capifs_file_inode_operations;
 
-       dentry = get_node(number);
        if (!IS_ERR(dentry) && !dentry->d_inode)
                d_instantiate(dentry, inode);
        mutex_unlock(&capifs_root->d_inode->i_mutex);