fs: Use rename lock and RCU for multi-step operations

[pandora-kernel.git] / fs / autofs4 / waitq.c

diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 2341375..4be8f77 100644 (file)
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -186,16 +186,25 @@ static int autofs4_getpath(struct autofs_sb_info *sbi,
 {
        struct dentry *root = sbi->sb->s_root;
        struct dentry *tmp;
-       char *buf = *name;
+       char *buf;
        char *p;
-       int len = 0;
-
+       int len;
+       unsigned seq;
+
+rename_retry:
+       buf = *name;
+       len = 0;
+       seq = read_seqbegin(&rename_lock);
+       rcu_read_lock();
        spin_lock(&dcache_lock);
        for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
                len += tmp->d_name.len + 1;
 
        if (!len || --len > NAME_MAX) {
                spin_unlock(&dcache_lock);
+               rcu_read_unlock();
+               if (read_seqretry(&rename_lock, seq))
+                       goto rename_retry;
                return 0;
        }
 
@@ -209,6 +218,9 @@ static int autofs4_getpath(struct autofs_sb_info *sbi,
                strncpy(p, tmp->d_name.name, tmp->d_name.len);
        }
        spin_unlock(&dcache_lock);
+       rcu_read_unlock();
+       if (read_seqretry(&rename_lock, seq))
+               goto rename_retry;
 
        return len;
 }