[dm-devel] [PATCH 7/7] libmultipath: Fixup 'DM_DEVICE_RELOAD' handling

[Hannes Reinecke]

libdevmapper has the 'quirk' that DM_DEVICE_CREATE is translated
internally into a create/load/resume sequence, and the associated
cookie will wait for the last 'resume' to complete.
However, DM_DEVICE_RELOAD has no such translation, so if there
is a cookie assigned to it the caller _cannot_ wait for it,
as the cookie will only ever be completed upon the next
DM_DEVICE_RESUME.
multipathd already has some provisions for that (but even there
the cookie handling is dodgy), but 'multipath -r' doesn't know
about this.
So to avoid any future irritations this patch updates the
dm_addmad_reload() call to handle the call to DM_DEVICE_RESUME
correctly and removes the special handling from domap().

Signed-off-by: Hannes Reinecke <hare at suse.de>
---
 libmultipath/configure.c | 18 ++++--------------
 libmultipath/devmapper.c | 31 ++++++++++++++++++++++++-------
 libmultipath/devmapper.h |  2 +-
 3 files changed, 29 insertions(+), 22 deletions(-)

diff --git a/libmultipath/configure.c b/libmultipath/configure.c
index 708dae8..a4a2c44 100644
--- a/libmultipath/configure.c
+++ b/libmultipath/configure.c
@@ -625,16 +625,11 @@ domap (struct multipath * mpp, char * params)
 		break;
 
 	case ACT_RELOAD:
-		r = dm_addmap_reload(mpp, params);
-		if (r)
-			r = dm_simplecmd_noflush(DM_DEVICE_RESUME, mpp->alias,
-						 MPATH_UDEV_RELOAD_FLAG);
+		r = dm_addmap_reload(mpp, params, 0);
 		break;
 
 	case ACT_RESIZE:
-		r = dm_addmap_reload(mpp, params);
-		if (r)
-			r = dm_simplecmd_flush(DM_DEVICE_RESUME, mpp->alias, 0);
+		r = dm_addmap_reload(mpp, params, 1);
 		break;
 
 	case ACT_RENAME:
@@ -643,13 +638,8 @@ domap (struct multipath * mpp, char * params)
 
 	case ACT_FORCERENAME:
 		r = dm_rename(mpp->alias_old, mpp->alias);
-		if (r) {
-			r = dm_addmap_reload(mpp, params);
-			if (r)
-				r = dm_simplecmd_noflush(DM_DEVICE_RESUME,
-							 mpp->alias,
-							 MPATH_UDEV_RELOAD_FLAG);
-		}
+		if (r)
+			r = dm_addmap_reload(mpp, params, 0);
 		break;
 
 	default:
diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
index 6983ab6..6d1a5d6 100644
--- a/libmultipath/devmapper.c
+++ b/libmultipath/devmapper.c
@@ -312,7 +312,8 @@ dm_addmap (int task, const char *target, struct multipath *mpp,
 	if (mpp->attribute_flags & (1 << ATTR_GID) &&
 	    !dm_task_set_gid(dmt, mpp->gid))
 		goto freeout;
-	condlog(4, "%s: addmap [0 %llu %s %s]", mpp->alias, mpp->size,
+	condlog(4, "%s: %s [0 %llu %s %s]", mpp->alias,
+		task == DM_DEVICE_RELOAD ? "reload" : "addmap", mpp->size,
 		target, params);
 
 	dm_task_no_open_count(dmt);
@@ -371,12 +372,28 @@ dm_addmap_create (struct multipath *mpp, char * params) {
 #define ADDMAP_RO 1
 
 extern int
-dm_addmap_reload (struct multipath *mpp, char *params) {
-	if (dm_addmap(DM_DEVICE_RELOAD, TGT_MPATH, mpp, params, ADDMAP_RW))
-		return 1;
-	if (errno != EROFS)
-		return 0;
-	return dm_addmap(DM_DEVICE_RELOAD, TGT_MPATH, mpp, params, ADDMAP_RO);
+dm_addmap_reload (struct multipath *mpp, char *params, int flush)
+{
+	int r;
+	uint16_t udev_flags = flush ? 0 : MPATH_UDEV_RELOAD_FLAG;
+
+	/*
+	 * DM_DEVICE_RELOAD cannot wait on a cookie, as
+	 * the cookie will only ever be released after an
+	 * DM_DEVICE_RESUME. So call DM_DEVICE_RESUME
+	 * after each successful call to DM_DEVICE_RELOAD.
+	 */
+	r = dm_addmap(DM_DEVICE_RELOAD, TGT_MPATH, mpp, params, ADDMAP_RW);
+	if (!r) {
+		if (errno != EROFS)
+			return 0;
+		r = dm_addmap(DM_DEVICE_RELOAD, TGT_MPATH, mpp,
+			      params, ADDMAP_RO);
+	}
+	if (r)
+		r = dm_simplecmd(DM_DEVICE_RESUME, mpp->alias, flush,
+				 1, udev_flags, 0);
+	return r;
 }
 
 extern int
diff --git a/libmultipath/devmapper.h b/libmultipath/devmapper.h
index bc13b07..b5df369 100644
--- a/libmultipath/devmapper.h
+++ b/libmultipath/devmapper.h
@@ -18,7 +18,7 @@ int dm_drv_version (unsigned int * version, char * str);
 int dm_simplecmd_flush (int, const char *, uint16_t);
 int dm_simplecmd_noflush (int, const char *, uint16_t);
 int dm_addmap_create (struct multipath *mpp, char *params);
-int dm_addmap_reload (struct multipath *mpp, char *params);
+int dm_addmap_reload (struct multipath *mpp, char *params, int flush);
 int dm_map_present (const char *);
 int dm_get_map(const char *, unsigned long long *, char *);
 int dm_get_status(char *, char *);
-- 
2.6.6