[PATCH v2 4/7] ceph: add ceph_get_snap_parent_inode() support

[xiubli@redhat.com]

From: Xiubo Li <xiubli@redhat.com>

Get the parent inode for the snap directory ".snap", if the inode
is not a snap directory just return it with the reference increased.

Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
 fs/ceph/snap.c  | 24 ++++++++++++++++++++++++
 fs/ceph/super.h |  1 +
 2 files changed, 25 insertions(+)

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index 66a1a92cf579..5e9656926dc7 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -1247,3 +1247,27 @@ void ceph_cleanup_snapid_map(struct ceph_mds_client *mdsc)
 		kfree(sm);
 	}
 }
+
+/*
+ * Get the parent inode for the snap directory ".snap",
+ * if the inode is not a snap directory just return it
+ * with the reference increased.
+ */
+struct inode *ceph_get_snap_parent_inode(struct inode *inode)
+{
+	struct inode *pinode;
+
+	if (ceph_snap(inode) == CEPH_SNAPDIR) {
+		struct ceph_vino vino = {
+			.ino = ceph_ino(inode),
+			.snap = CEPH_NOSNAP,
+		};
+		pinode = ceph_find_inode(inode->i_sb, vino);
+		BUG_ON(!pinode);
+	} else {
+		ihold(inode);
+		pinode = inode;
+	}
+
+	return pinode;
+}
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index d5a4d311f4c2..e7c69ca5e289 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -969,6 +969,7 @@ extern void ceph_put_snapid_map(struct ceph_mds_client* mdsc,
 				struct ceph_snapid_map *sm);
 extern void ceph_trim_snapid_map(struct ceph_mds_client *mdsc);
 extern void ceph_cleanup_snapid_map(struct ceph_mds_client *mdsc);
+extern struct inode *ceph_get_snap_parent_inode(struct inode *inode);
 void ceph_umount_begin(struct super_block *sb);
 
 
-- 
2.27.0