eCryptfs: Invalidate dcache entries when lower i_nlink is zero

commit 5556e7e6d30e8e9b5ee51b0e5edd526ee80e5e36 upstream.

Consider eCryptfs dcache entries to be stale when the corresponding
lower inode's i_nlink count is zero. This solves a problem caused by the
lower inode being directly modified, without going through the eCryptfs
mount, leaving stale eCryptfs dentries cached and the eCryptfs inode's
i_nlink count not being cleared.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Reported-by: Richard Weinberger <richard@nod.at>
[bwh: Backported to 3.2:
 - Test d_revalidate pointer directly rather than a DCACHE_OP flag
 - Open-code d_inode()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/ecryptfs/dentry.c b/fs/ecryptfs/dentry.c
index 534c1d4..eba8f1d 100644 (file)
--- a/fs/ecryptfs/dentry.c
+++ b/fs/ecryptfs/dentry.c
@@ -55,26 +55,26 @@ static int ecryptfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 
        lower_dentry = ecryptfs_dentry_to_lower(dentry);
        lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
-       if (!lower_dentry->d_op || !lower_dentry->d_op->d_revalidate)
-               goto out;
-       if (nd) {
-               dentry_save = nd->path.dentry;
-               vfsmount_save = nd->path.mnt;
-               nd->path.dentry = lower_dentry;
-               nd->path.mnt = lower_mnt;
-       }
-       rc = lower_dentry->d_op->d_revalidate(lower_dentry, nd);
-       if (nd) {
-               nd->path.dentry = dentry_save;
-               nd->path.mnt = vfsmount_save;
+       if (lower_dentry->d_op && lower_dentry->d_op->d_revalidate) {
+               if (nd) {
+                       dentry_save = nd->path.dentry;
+                       vfsmount_save = nd->path.mnt;
+                       nd->path.dentry = lower_dentry;
+                       nd->path.mnt = lower_mnt;
+               }
+               rc = lower_dentry->d_op->d_revalidate(lower_dentry, nd);
+               if (nd) {
+                       nd->path.dentry = dentry_save;
+                       nd->path.mnt = vfsmount_save;
+               }
        }
        if (dentry->d_inode) {
-               struct inode *lower_inode =
-                       ecryptfs_inode_to_lower(dentry->d_inode);
+               struct inode *inode = dentry->d_inode;
 
-               fsstack_copy_attr_all(dentry->d_inode, lower_inode);
+               fsstack_copy_attr_all(inode, ecryptfs_inode_to_lower(inode));
+               if (!inode->i_nlink)
+                       return 0;
        }
-out:
        return rc;
 }