From: Hannes Reinecke When multipath devices are being used as disks for VM Guests any partition scanning / setup should be done within the VM Guest, not from host. So we need to a mechanism to switch off partition scanning and creation via kpartx. The new 'no_partitions' feature serves as a notifier to kpartx to _not_ create partitions on these multipath devices. Signed-off-by: Hannes Reinecke Signed-off-by: Mike Snitzer Reviewed-by: Chandra Seetharaman FIXME "no_partitions" name is ambiguous to me - "ignore_partition_table" better perhaps? FIXME But what sets this, and would a udev/cookie mechanism be more appropriate? (Why are mpath devices special?) --- drivers/md/dm-mpath.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) Index: linux/drivers/md/dm-mpath.c =================================================================== --- linux.orig/drivers/md/dm-mpath.c +++ linux/drivers/md/dm-mpath.c @@ -86,6 +86,7 @@ struct multipath { unsigned queue_if_no_path:1; /* Queue I/O if last path fails? */ unsigned saved_queue_if_no_path:1; /* Saved state during suspension */ unsigned use_default_hw_handler:1; /* Use attached device handler */ + unsigned no_partitions:1; /* Avoid partition scanning */ unsigned pg_init_retries; /* Number of times to retry pg_init */ unsigned pg_init_count; /* Number of times pg_init called */ @@ -772,7 +773,7 @@ static int parse_features(struct dm_arg_ const char *arg_name; static struct dm_arg _args[] = { - {0, 6, "invalid number of feature args"}, + {0, 7, "invalid number of feature args"}, {1, 50, "pg_init_retries must be between 1 and 50"}, {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"}, }; @@ -798,6 +799,11 @@ static int parse_features(struct dm_arg_ continue; } + if (!strcasecmp(arg_name, "no_partitions")) { + m->no_partitions = 1; + continue; + } + if (!strcasecmp(arg_name, "pg_init_retries") && (argc >= 1)) { r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error); @@ -1382,7 +1388,8 @@ static int multipath_status(struct dm_ta DMEMIT("%u ", m->queue_if_no_path + (m->pg_init_retries > 0) * 2 + (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 + - m->use_default_hw_handler); + m->use_default_hw_handler + + m->no_partitions); if (m->queue_if_no_path) DMEMIT("queue_if_no_path "); if (m->pg_init_retries) @@ -1391,6 +1398,8 @@ static int multipath_status(struct dm_ta DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs); if (m->use_default_hw_handler) DMEMIT("default_hw_handler "); + if (m->no_partitions) + DMEMIT("no_partitions "); } if (!m->hw_handler_name || type == STATUSTYPE_INFO)