From: Lars Ellenberg <lars.ellenb...@linbit.com>
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.reis...@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenb...@linbit.com>
---
drivers/block/drbd/drbd_nl.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 5e4adff..4703f1a 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -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;
+ blk_queue_max_discard_sectors(q, DRBD_MAX_DISCARD_SECTORS);
+
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);
-
+ /* 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)
--
1.9.1
--
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