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drbd: fix queue limit setup for discard 

We cannot possibly support SECDISCARD, even if all backend devices would
support it: if our peer is currently unreachable, some instance of the
data may obviously still be recoverable.

We did not set discard_granularity at all.  We don't really care (yet),
we only pass them on, so for now, set our granularity to one sector.
blkdev_stack_limits() takes care of the rest.

If we decide we cannot support discards,
not only clear the (not user visible) QUEUE_FLAG_DISCARD,
but set both (user visible) discard_granularity and max_discard_sectors
to zero, to avoid confusion with e.g. lsblk -D.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Lars Ellenberg 2015-03-24 21:46:29 +01:00 committed by Jens Axboe
parent edb5e5f63d
commit 088b70526d
1 changed files with 14 additions and 9 deletions
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23
drivers/block/drbd/drbd_nl.c
View File

@ -1168,21 +1168,20 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
if (b) {
struct drbd_connection *connection = first_peer_device(device)->connection;
if (blk_queue_discard(b) &&
(connection->cstate < C_CONNECTED || connection->agreed_features & FF_TRIM)) {
/* For now, don't allow more than one activity log extent worth of data
* to be discarded in one go. We may need to rework drbd_al_begin_io()
* to allow for even larger discard ranges */
blk_queue_max_discard_sectors(q, DRBD_MAX_DISCARD_SECTORS);
if (blk_queue_discard(b) &&
(connection->cstate < C_CONNECTED || connection->agreed_features & FF_TRIM)) {
/* We don't care, stacking below should fix it for the local device.
* Whether or not it is a suitable granularity on the remote device
* is not our problem, really. If you care, you need to
* use devices with similar topology on all peers. */
q->limits.discard_granularity = 512;
queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
/* REALLY? Is stacking secdiscard "legal"? */
if (blk_queue_secdiscard(b))
queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, q);
} else {
blk_queue_max_discard_sectors(q, 0);
queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
queue_flag_clear_unlocked(QUEUE_FLAG_SECDISCARD, q);
q->limits.discard_granularity = 0;
}
blk_queue_stack_limits(q, b);
@ -1194,6 +1193,12 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
q->backing_dev_info.ra_pages = b->backing_dev_info.ra_pages;
}
}
/* To avoid confusion, if this queue does not support discard, clear
* max_discard_sectors, which is what lsblk -D reports to the user. */
if (!blk_queue_discard(q)) {
blk_queue_max_discard_sectors(q, 0);
q->limits.discard_granularity = 0;
}
}
void drbd_reconsider_max_bio_size(struct drbd_device *device, struct drbd_backing_dev *bdev)