ceph: switch ceph_lookup/atomic_open() to use new fscrypt helper

Instead of setting the no-key dentry, use the new
fscrypt_prepare_lookup_partial() helper.  We still need to mark the
directory as incomplete if the directory was just unlocked.

In ceph_atomic_open() this fixes a bug where a dentry is incorrectly
set with DCACHE_NOKEY_NAME when 'dir' has been evicted but the key is
still available (for example, where there's a drop_caches).

Signed-off-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Author: Luís Henriques

fs/ceph/dir.c

@@ -785,14 +785,15 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
 		return ERR_PTR(-ENAMETOOLONG);
 
 	if (IS_ENCRYPTED(dir)) {
-		err = ceph_fscrypt_prepare_readdir(dir);
+		bool had_key = fscrypt_has_encryption_key(dir);
+
+		err = fscrypt_prepare_lookup_partial(dir, dentry);
 		if (err < 0)
 			return ERR_PTR(err);
-		if (!fscrypt_has_encryption_key(dir)) {
-			spin_lock(&dentry->d_lock);
-			dentry->d_flags |= DCACHE_NOKEY_NAME;
-			spin_unlock(&dentry->d_lock);
-		}
+
+		/* mark directory as incomplete if it has been unlocked */
+		if (!had_key && fscrypt_has_encryption_key(dir))
+			ceph_dir_clear_complete(dir);
 	}
 
 	/* can we conclude ENOENT locally? */

fs/ceph/file.c

@@ -791,11 +791,9 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
 	ihold(dir);
 	if (IS_ENCRYPTED(dir)) {
 		set_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags);
-		if (!fscrypt_has_encryption_key(dir)) {
-			spin_lock(&dentry->d_lock);
-			dentry->d_flags |= DCACHE_NOKEY_NAME;
-			spin_unlock(&dentry->d_lock);
-		}
+		err = fscrypt_prepare_lookup_partial(dir, dentry);
+		if (err < 0)
+			goto out_req;
 	}
 
 	if (flags & O_CREAT) {