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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 <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
This commit is contained in:
Mike Snitzer 2013-09-19 18:49:11 -04:00
parent f84cb8a46a
commit b60ab990cc
1 changed files with 11 additions and 3 deletions
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14
drivers/md/dm-thin.c
View File

@ -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;
}