From b60ab990ccdf34b0159bf5ff52f4acee7c940d78 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 19 Sep 2013 18:49:11 -0400 Subject: dm thin: do not expose non-zero discard limits if discards disabled Fix issue where the block layer would stack the discard limits of the pool's data device even if the "ignore_discard" pool feature was specified. The pool and thin device(s) still had discards disabled because the QUEUE_FLAG_DISCARD request_queue flag wasn't set. But to avoid user confusion when "ignore_discard" is used: both the pool device and the thin device(s) have zeroes for all discard limits. Also, always set discard_zeroes_data_unsupported in targets because they should never advertise the 'discard_zeroes_data' capability (even if the pool's data device supports it). Signed-off-by: Mike Snitzer Acked-by: Joe Thornber --- drivers/md/dm-thin.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) (limited to 'drivers/md') diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index ed06342..2c0cf51 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -2095,6 +2095,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) * them down to the data device. The thin device's discard * processing will cause mappings to be removed from the btree. */ + ti->discard_zeroes_data_unsupported = true; if (pf.discard_enabled && pf.discard_passdown) { ti->num_discard_bios = 1; @@ -2104,7 +2105,6 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) * thin devices' discard limits consistent). */ ti->discards_supported = true; - ti->discard_zeroes_data_unsupported = true; } ti->private = pt; @@ -2689,8 +2689,16 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits) * They get transferred to the live pool in bind_control_target() * called from pool_preresume(). */ - if (!pt->adjusted_pf.discard_enabled) + if (!pt->adjusted_pf.discard_enabled) { + /* + * Must explicitly disallow stacking discard limits otherwise the + * block layer will stack them if pool's data device has support. + * QUEUE_FLAG_DISCARD wouldn't be set but there is no way for the + * user to see that, so make sure to set all discard limits to 0. + */ + limits->discard_granularity = 0; return; + } disable_passdown_if_not_supported(pt); @@ -2826,10 +2834,10 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv) ti->per_bio_data_size = sizeof(struct dm_thin_endio_hook); /* In case the pool supports discards, pass them on. */ + ti->discard_zeroes_data_unsupported = true; if (tc->pool->pf.discard_enabled) { ti->discards_supported = true; ti->num_discard_bios = 1; - ti->discard_zeroes_data_unsupported = true; /* Discard bios must be split on a block boundary */ ti->split_discard_bios = true; } -- cgit v1.1