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>

1 files changed, 17 insertions, 15 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index ed296ec121d1..31d27f8f8261 100644
--- 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;
 }
 
 /*