[sheepdog] [PATCH 4/4] sheepdog: handle a case of snapshot -> failover

[Hitoshi Mitake]

If refreshed inode is snapshot, we can reload entire inode and switch
to working VDI immediately. It is required by the new refreshing
condition introduced in the commit 8f781f02ab of sheepdog.

Cc: Teruaki Ishizaki <ishizaki.teruaki at lab.ntt.co.jp>
Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
---
 usr/bs_sheepdog.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/usr/bs_sheepdog.c b/usr/bs_sheepdog.c
index 56630ac..99519ef 100644
--- a/usr/bs_sheepdog.c
+++ b/usr/bs_sheepdog.c
@@ -704,6 +704,34 @@ static int reload_inode(struct sheepdog_access_info *ai, int is_snapshot)
 			ret = -1;
 			goto ret;
 		}
+
+		if (!!ai->inode.snap_ctime) {
+			/*
+			 * This is a case like below:
+			 * take snapshot -> write something -> failover
+			 *
+			 * Because invalidated inode is readonly and latest
+			 * working VDI can have COWed objects, we need to
+			 * resolve VID and reload its entire inode object.
+			 */
+			memset(tag, 0, sizeof(tag));
+
+			ret = find_vdi_name(ai, ai->inode.name, CURRENT_VDI_ID,
+					    tag, &vid, 1);
+			if (ret) {
+				ret = -1;
+				goto ret;
+			}
+
+			ret = read_object(ai, (char *)&ai->inode,
+					  vid_to_vdi_oid(vid),
+					  ai->inode.nr_copies, SD_INODE_SIZE, 0,
+					  &need_reload);
+			if (ret) {
+				ret = -1;
+				goto ret;
+			}
+		}
 	}
 
 	ai->min_dirty_data_idx = UINT32_MAX;
-- 
1.9.1