[PATCH 6/6] sheepdog: handle an inconsistent state of metadata

This commit lets the sheepdog driver to handle the case of no VDI
found during inode reloading. It can happen because sheepdog does not
provide metadata transaction.

Cc: Teruaki Ishizaki <[email protected]>
Cc: Takashi Menjo <[email protected]>
Tested-by: Takashi Menjo <[email protected]>
Signed-off-by: Hitoshi Mitake <[email protected]>
---
 usr/bs_sheepdog.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/usr/bs_sheepdog.c b/usr/bs_sheepdog.c
index 12bcfd9..fc91ad1 100644
--- a/usr/bs_sheepdog.c
+++ b/usr/bs_sheepdog.c
@@ -750,6 +750,7 @@ static int read_write_object(struct sheepdog_access_info *ai, char *buf,
 	unsigned int wlen, rlen;
 	int ret;
 
+retry:
 	memset(&hdr, 0, sizeof(hdr));
 
 	hdr.proto_ver = SD_PROTO_VER;
@@ -791,6 +792,17 @@ static int read_write_object(struct sheepdog_access_info *ai, char *buf,
 	case SD_RES_READONLY:
 		*need_reload = 1;
 		return 0;
+	case SD_RES_NO_OBJ:
+		if (!write && oid & (UINT64_C(1) << 63))
+			/*
+			 * sheepdog doesn't provide a mechanism of metadata
+			 * transaction, so tgt can see an inconsistent state
+			 * like this (old working VDI became snapshot already
+			 * but an inode object of new working VDI isn't
+			 * created yet).
+			 */
+			goto retry;
+		return -1;
 	default:
 		eprintf("%s (oid: %" PRIx64 ", old_oid: %" PRIx64 ")\n",
 			sd_strerror(rsp->result), oid, old_oid);
-- 
2.7.4