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>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/isdn/capi/capifs.c b/drivers/isdn/capi/capifs.c
index 8f9f3b5a3e8c..bff72d81f263 100644
--- 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);