[dm-devel] [PATCH v2 6/7] multipath: delegate flushing maps to multipathd

[Benjamin Marzinski]

Since there can be problems with removing maps outside of multipathd,
multipath should attempt to delegate this command to multipathd.
However, multipathd doesn't attempt to suspend the device, in order
to avoid potential hangs. If delegating to multipathd fails, multipath
should try the remove itself.

Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
---
 multipath/main.c      | 14 ++++++++++++++
 multipath/multipath.8 |  4 ++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/multipath/main.c b/multipath/main.c
index 101fd656..6a24e483 100644
--- a/multipath/main.c
+++ b/multipath/main.c
@@ -820,6 +820,20 @@ int delegate_to_multipathd(enum mpath_cmds cmd,
 	if (cmd == CMD_CREATE && conf->force_reload == FORCE_RELOAD_YES) {
 		p += snprintf(p, n, "reconfigure");
 	}
+	else if (cmd == CMD_FLUSH_ONE && dev && dev_type == DEV_DEVMAP) {
+		p += snprintf(p, n, "del map %s", dev);
+		/* multipathd doesn't try as hard, to avoid potentially
+		 * hanging. If it fails, retry with the regular multipath
+		 * command */
+		r = NOT_DELEGATED;
+	}
+	else if (cmd == CMD_FLUSH_ALL) {
+		p += snprintf(p, n, "del maps");
+		/* multipathd doesn't try as hard, to avoid potentially
+		 * hanging. If it fails, retry with the regular multipath
+		 * command */
+		r = NOT_DELEGATED;
+	}
 	/* Add other translations here */
 
 	if (strlen(command) == 0)
diff --git a/multipath/multipath.8 b/multipath/multipath.8
index 6fb8645a..5b29a5d9 100644
--- a/multipath/multipath.8
+++ b/multipath/multipath.8
@@ -125,11 +125,11 @@ the system.
 Other operation modes are chosen by using one of the following command line switches:
 .TP
 .B \-f
-Flush (remove) a multipath device map specified as parameter, if unused.
+Flush (remove) a multipath device map specified as parameter, if unused. This operation is delegated to the multipathd daemon if it's running.
 .
 .TP
 .B \-F
-Flush (remove) all unused multipath device maps.
+Flush (remove) all unused multipath device maps. This operation is delegated to the multipathd daemon if it's running.
 .
 .TP
 .B \-l
-- 
2.17.2