vg_read: look up vgid from namedev-dct-dupvgnamesD

When vg_read is given a vgid, it looks up the vgname
in lvmcache.  Now, in the same way, when vg_read is
given a vgname, look up the vgid in lvmcache.

3 files changed, 27 insertions, 1 deletions

diff --git a/lib/cache/lvmcache.c b/lib/cache/lvmcache.c
index 985ff43a5..e375388fb 100644
--- a/lib/cache/lvmcache.c
+++ b/lib/cache/lvmcache.c
@@ -614,6 +614,23 @@ const char *lvmcache_vgname_from_vgid(struct dm_pool *mem, const char *vgid)
 	return vgname;
 }
 
+const char *lvmcache_vgid_from_vgname(struct cmd_context *cmd, const char *vgname)
+{
+	struct lvmcache_vginfo *vginfo;
+
+	if (!(vginfo = dm_hash_lookup(_vgname_hash, vgname)))
+		return_NULL;
+
+	if (!vginfo->next)
+		return dm_pool_strdup(cmd->mem, vginfo->vgid);
+
+	/*
+	 * There are multiple VGs with this name to choose from.
+	 * Return an error because we don't know which VG is intended.
+	 */
+	return NULL;
+}
+
 static int _info_is_valid(struct lvmcache_info *info)
 {
 	if (info->status & CACHE_INVALID)
diff --git a/lib/cache/lvmcache.h b/lib/cache/lvmcache.h
index b968a12e9..509cfd6f6 100644
--- a/lib/cache/lvmcache.h
+++ b/lib/cache/lvmcache.h
@@ -99,6 +99,7 @@ struct lvmcache_vginfo *lvmcache_vginfo_from_vgname(const char *vgname,
 struct lvmcache_vginfo *lvmcache_vginfo_from_vgid(const char *vgid);
 struct lvmcache_info *lvmcache_info_from_pvid(const char *pvid, int valid_only);
 const char *lvmcache_vgname_from_vgid(struct dm_pool *mem, const char *vgid);
+const char *lvmcache_vgid_from_vgname(struct cmd_context *cmd, const char *vgname);
 struct device *lvmcache_device_from_pvid(struct cmd_context *cmd, const struct id *pvid,
 				unsigned *scan_done_once, uint64_t *label_sector);
 const char *lvmcache_pvid_from_devname(struct cmd_context *cmd,
diff --git a/lib/metadata/metadata.c b/lib/metadata/metadata.c
index bf030d37f..ec645ae14 100644
--- a/lib/metadata/metadata.c
+++ b/lib/metadata/metadata.c
@@ -3617,8 +3617,16 @@ static struct volume_group *_vg_read(struct cmd_context *cmd,
 	}
 
 	/* Now determine the correct vgname if none was supplied */
-	if (!vgname && !(vgname = lvmcache_vgname_from_vgid(cmd->mem, vgid)))
+	if (!vgname && !(vgname = lvmcache_vgname_from_vgid(cmd->mem, vgid))) {
+		log_debug_metadata("Cache did not find VG name from vgid %.32s", vgid);
 		return_NULL;
+	}
+
+	/* Determine the correct vgid if none was supplied */
+	if (!vgid && !(vgid = lvmcache_vgid_from_vgname(cmd, vgname))) {
+		log_debug_metadata("Cache did not find VG vgid from name %s", vgname);
+		return_NULL;
+	}
 
 	if (use_precommitted && !(fmt->features & FMT_PRECOMMIT))
 		use_precommitted = 0;