ceph: protect d_parent access in ceph_d_revalidate

Protect d_parent with d_lock.  Carry a reference.  Simplify the flow so
that there is a single exit point and cleanup.

Reviewed-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index ed296ec..31d27f8 100644 (file)
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1024,36 +1024,38 @@ static int dir_lease_is_valid(struct inode *dir, struct dentry *dentry)
  */
 static int ceph_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
+       int valid = 0;
        struct inode *dir;
 
        if (nd && nd->flags & LOOKUP_RCU)
                return -ECHILD;
 
-       dir = dentry->d_parent->d_inode;
-
        dout("d_revalidate %p '%.*s' inode %p offset %lld\n", dentry,
             dentry->d_name.len, dentry->d_name.name, dentry->d_inode,
             ceph_dentry(dentry)->offset);
 
+       dir = ceph_get_dentry_parent_inode(dentry);
+
        /* always trust cached snapped dentries, snapdir dentry */
        if (ceph_snap(dir) != CEPH_NOSNAP) {
                dout("d_revalidate %p '%.*s' inode %p is SNAPPED\n", dentry,
                     dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
-               goto out_touch;
+               valid = 1;
+       } else if (dentry->d_inode &&
+                  ceph_snap(dentry->d_inode) == CEPH_SNAPDIR) {
+               valid = 1;
+       } else if (dentry_lease_is_valid(dentry) ||
+                  dir_lease_is_valid(dir, dentry)) {
+               valid = 1;
        }
-       if (dentry->d_inode && ceph_snap(dentry->d_inode) == CEPH_SNAPDIR)
-               goto out_touch;
 
-       if (dentry_lease_is_valid(dentry) ||
-           dir_lease_is_valid(dir, dentry))
-               goto out_touch;
-
-       dout("d_revalidate %p invalid\n", dentry);
-       d_drop(dentry);
-       return 0;
-out_touch:
-       ceph_dentry_lru_touch(dentry);
-       return 1;
+       dout("d_revalidate %p %s\n", dentry, valid ? "valid" : "invalid");
+       if (valid)
+               ceph_dentry_lru_touch(dentry);
+       else
+               d_drop(dentry);
+       iput(dir);
+       return valid;
 }
 
 /*