From d54eaa5a0fde0a202e4e91f200f818edcef15bee Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 21 Dec 2012 20:23:36 +0000 Subject: dm: prepare to support WRITE SAME Allow targets to opt in to WRITE SAME support by setting 'num_write_same_requests' in the dm_target structure. A dm device will only advertise WRITE SAME support if all its targets and all its underlying devices support it. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- drivers/md/dm-table.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index fa295579003..6be58b69637 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -1414,6 +1414,33 @@ static bool dm_table_all_devices_attribute(struct dm_table *t, return 1; } +static int device_not_write_same_capable(struct dm_target *ti, struct dm_dev *dev, + sector_t start, sector_t len, void *data) +{ + struct request_queue *q = bdev_get_queue(dev->bdev); + + return q && !q->limits.max_write_same_sectors; +} + +static bool dm_table_supports_write_same(struct dm_table *t) +{ + struct dm_target *ti; + unsigned i = 0; + + while (i < dm_table_get_num_targets(t)) { + ti = dm_table_get_target(t, i++); + + if (!ti->num_write_same_requests) + return false; + + if (!ti->type->iterate_devices || + !ti->type->iterate_devices(ti, device_not_write_same_capable, NULL)) + return false; + } + + return true; +} + void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, struct queue_limits *limits) { @@ -1445,7 +1472,8 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, else queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q); - q->limits.max_write_same_sectors = 0; + if (!dm_table_supports_write_same(t)) + q->limits.max_write_same_sectors = 0; dm_table_set_integrity(t); -- cgit v1.2.3