[sheepdog] [PATCH v2 3/3] md: make MD support as always enabled

[Liu Yuan]

From: Liu Yuan <tailai.ly at taobao.com>

Currently, we can plug new disks even MD isn't enabled. Following process

$ sheep /store # MD isn't enabled
$ collie node md plug /new_disk

will cause big trouble because plugging will succeed and force a recovery where
old /store isn't counted in the disk arrays.

To avoid such random careless opertaion and keep simplicity, this patch:

Make MD support as always enabled then the interface to be more upgradeing friendly:

   $ sheep /store # will enable MD and meta-store and object-store will share the same /store
   $ sheep /metastore,/disk1{,.../diskN,...} # works as before

Signed-off-by: Liu Yuan <tailai.ly at taobao.com>
---
 sheep/md.c         |   14 --------------
 sheep/sheep_priv.h |    1 -
 sheep/store.c      |   16 +++++++++++++---
 3 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/sheep/md.c b/sheep/md.c
index 8027707..f60b58b 100644
--- a/sheep/md.c
+++ b/sheep/md.c
@@ -327,8 +327,6 @@ reinit:
 	}
 	calculate_vdisks(md_disks, md_nr_disks, total);
 	md_nr_vds = disks_to_vdisks(md_disks, md_nr_disks, md_vds);
-	if (!sys->enable_md)
-		sys->enable_md = true;
 
 	return total;
 }
@@ -338,9 +336,6 @@ char *get_object_path(uint64_t oid)
 	struct vdisk *vd;
 	char *p;
 
-	if (!sys->enable_md)
-		return obj_path;
-
 	pthread_rwlock_rdlock(&md_lock);
 	vd = oid_to_vdisk(oid);
 	p = md_disks[vd->idx].path;
@@ -363,9 +358,6 @@ int for_each_object_in_wd(int (*func)(uint64_t oid, char *path, void *arg),
 {
 	int i, ret = SD_RES_SUCCESS;
 
-	if (!sys->enable_md)
-		return for_each_object_in_path(obj_path, func, cleanup, arg);
-
 	pthread_rwlock_rdlock(&md_lock);
 	for (i = 0; i < md_nr_disks; i++) {
 		ret = for_each_object_in_path(md_disks[i].path, func,
@@ -381,9 +373,6 @@ int for_each_obj_path(int (*func)(char *path))
 {
 	int i, ret = SD_RES_SUCCESS;
 
-	if (!sys->enable_md)
-		return func(obj_path);
-
 	pthread_rwlock_rdlock(&md_lock);
 	for (i = 0; i < md_nr_disks; i++) {
 		ret = func(md_disks[i].path);
@@ -430,9 +419,6 @@ int md_handle_eio(char *fault_path)
 {
 	struct md_work *mw;
 
-	if (!sys->enable_md)
-		return SD_RES_EIO;
-
 	if (nr_online_disks() == 0)
 		return SD_RES_EIO;
 
diff --git a/sheep/sheep_priv.h b/sheep/sheep_priv.h
index 1119230..bb7a522 100644
--- a/sheep/sheep_priv.h
+++ b/sheep/sheep_priv.h
@@ -125,7 +125,6 @@ struct cluster_info {
 	bool backend_dio;
 	/* upgrade data layout before starting service if necessary*/
 	bool upgrade;
-	bool enable_md;
 };
 
 struct siocb {
diff --git a/sheep/store.c b/sheep/store.c
index e6beb4b..a961f9f 100644
--- a/sheep/store.c
+++ b/sheep/store.c
@@ -294,9 +294,19 @@ static int init_obj_path(const char *base_path, char *argp)
 
 	/* Eat up the first component */
 	strtok(argp, ",");
-	while ((p = strtok(NULL, ",")))
-		md_add_disk(p);
-
+	p = strtok(NULL, ",");
+	if (!p) {
+		/*
+		 * If We have only one path, meta-store and object-store share
+		 * it. This is helpful to upgrade old sheep cluster to
+		 * the MD-enabled.
+		 */
+		md_add_disk(obj_path);
+	} else {
+		do {
+			md_add_disk(p);
+		} while ((p = strtok(NULL, ",")));
+	}
 	return init_path(obj_path, NULL);
 }
 
-- 
1.7.9.5