From 5931286cb71114c0f34e51fc7f357dceec139ca1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20B=C3=B6hmwalder?=
<christoph.boehmwalder@linbit.com>
Date: Tue, 13 Aug 2024 12:26:02 +0200
Subject: [PATCH 15/32] drbd: atomically update queue limits in
drbd_reconsider_queue_parameters
Switch drbd_reconsider_queue_parameters to set up the queue parameters
in an on-stack queue_limits structure and apply the limits atomically.
Remove various helpers that have become so trivial that they can be
folded into drbd_reconsider_queue_parameters.
Same idea as upstream kernel commit e6dfe748f09e ("drbd: atomically
update queue limits in drbd_reconsider_queue_parameters"), but with some
adaptations to DRBD 9.
---
drbd/drbd_nl.c | 136 ++++++++++++++++++++++---------------------------
1 file changed, 60 insertions(+), 76 deletions(-)
diff --git a/drbd/drbd_nl.c b/drbd/drbd_nl.c
index e3f508cd0421..7193ba0c77e3 100644
--- a/drbd/drbd_nl.c
+++ b/drbd/drbd_nl.c
@@ -2018,11 +2018,6 @@ static u32 common_connection_features(struct drbd_resource *resource)
return features;
}
-static void blk_queue_discard_granularity(struct request_queue *q, unsigned int granularity)
-{
- q->limits.discard_granularity = granularity;
-}
-
static unsigned int drbd_max_discard_sectors(struct drbd_resource *resource)
{
struct drbd_connection *connection;
@@ -2059,73 +2054,20 @@ static bool drbd_discard_supported(struct drbd_device *device,
return true;
}
-static void decide_on_discard_support(struct drbd_device *device,
- struct drbd_backing_dev *bdev)
-{
- struct request_queue *q = device->rq_queue;
- unsigned int max_discard_sectors;
-
- if (!drbd_discard_supported(device, bdev)) {
- blk_queue_discard_granularity(q, 0);
- blk_queue_max_discard_sectors(q, 0);
- return;
- }
-
- /*
- * We don't care for the granularity, really.
- *
- * Stacking limits 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.
- */
- blk_queue_discard_granularity(q, 512);
- max_discard_sectors = drbd_max_discard_sectors(device->resource);
- blk_queue_max_discard_sectors(q, max_discard_sectors);
-}
-
-static void fixup_write_zeroes(struct drbd_device *device, struct request_queue *q)
-{
- /* Fixup max_write_zeroes_sectors after blk_stack_limits():
- * if we can handle "zeroes" efficiently on the protocol,
- * we want to do that, even if our backend does not announce
- * max_write_zeroes_sectors itself. */
-
- /* If all peers announce WZEROES support, use it. Otherwise, rather
- * send explicit zeroes than rely on some discard-zeroes-data magic. */
- if (common_connection_features(device->resource) & DRBD_FF_WZEROES)
- q->limits.max_write_zeroes_sectors = DRBD_MAX_BBIO_SECTORS;
- else
- q->limits.max_write_zeroes_sectors = 0;
-}
-
-static void fixup_discard_support(struct drbd_device *device, struct request_queue *q)
-{
- unsigned int max_discard = device->rq_queue->limits.max_discard_sectors;
- unsigned int discard_granularity = device->rq_queue->limits.discard_granularity >> SECTOR_SHIFT;
-
- if (discard_granularity > max_discard) {
- blk_queue_discard_granularity(q, 0);
- blk_queue_max_discard_sectors(q, 0);
- }
-}
-
-void drbd_reconsider_queue_parameters(struct drbd_device *device, struct drbd_backing_dev *bdev)
+static void get_common_queue_limits(struct queue_limits *common_limits,
+ struct drbd_device *device)
{
- struct request_queue * const q = device->rq_queue;
- struct queue_limits common_limits = { 0 }; /* sizeof(struct queue_limits) ~ 110 bytes */
- struct queue_limits peer_limits = { 0 };
struct drbd_peer_device *peer_device;
- struct request_queue *b = NULL;
+ struct queue_limits peer_limits = { 0 };
- blk_set_stacking_limits(&common_limits);
+ blk_set_stacking_limits(common_limits);
/* This is the workaround for "bio would need to, but cannot, be split" */
- common_limits.seg_boundary_mask = PAGE_SIZE - 1;
- common_limits.max_hw_sectors = device->device_conf.max_bio_size >> SECTOR_SHIFT;
- common_limits.max_sectors = device->device_conf.max_bio_size >> SECTOR_SHIFT;
- common_limits.physical_block_size = device->device_conf.block_size;
- common_limits.logical_block_size = device->device_conf.block_size;
- common_limits.io_min = device->device_conf.block_size;
+ common_limits->seg_boundary_mask = PAGE_SIZE - 1;
+ common_limits->max_hw_sectors = device->device_conf.max_bio_size >> SECTOR_SHIFT;
+ common_limits->max_sectors = device->device_conf.max_bio_size >> SECTOR_SHIFT;
+ common_limits->physical_block_size = device->device_conf.block_size;
+ common_limits->logical_block_size = device->device_conf.block_size;
+ common_limits->io_min = device->device_conf.block_size;
rcu_read_lock();
for_each_peer_device_rcu(peer_device, device) {
@@ -2140,21 +2082,63 @@ void drbd_reconsider_queue_parameters(struct drbd_device *device, struct drbd_ba
peer_limits.io_opt = peer_device->q_limits.io_opt;
peer_limits.max_hw_sectors = peer_device->q_limits.max_bio_size >> SECTOR_SHIFT;
peer_limits.max_sectors = peer_device->q_limits.max_bio_size >> SECTOR_SHIFT;
- blk_stack_limits(&common_limits, &peer_limits, 0);
+ blk_stack_limits(common_limits, &peer_limits, 0);
}
rcu_read_unlock();
+}
+
+void drbd_reconsider_queue_parameters(struct drbd_device *device, struct drbd_backing_dev *bdev)
+{
+ struct request_queue * const q = device->rq_queue;
+ struct queue_limits lim;
+ struct request_queue *b = NULL;
+
+ lim = queue_limits_start_update(q);
+ get_common_queue_limits(&lim, device);
+
+ /*
+ * We don't care for the granularity, really.
+ * Stacking limits 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.
+ */
+ if (drbd_discard_supported(device, bdev)) {
+ lim.discard_granularity = 512;
+ lim.max_hw_discard_sectors = drbd_max_discard_sectors(device->resource);
+ } else {
+ lim.discard_granularity = 0;
+ lim.max_hw_discard_sectors = 0;
+ }
if (bdev) {
b = bdev->backing_bdev->bd_disk->queue;
- blk_stack_limits(&common_limits, &b->limits, 0);
- disk_update_readahead(device->vdisk);
+ blk_stack_limits(&lim, &b->limits, 0);
+ }
+
+ /*
+ * If we can handle "zeroes" efficiently on the protocol,
+ * we want to do that, even if our backend does not announce
+ * max_write_zeroes_sectors itself.
+ */
+ if (common_connection_features(device->resource) & DRBD_FF_WZEROES)
+ lim.max_write_zeroes_sectors = DRBD_MAX_BBIO_SECTORS;
+ else
+ lim.max_write_zeroes_sectors = 0;
+
+ if ((lim.discard_granularity >> SECTOR_SHIFT) >
+ lim.max_hw_discard_sectors) {
+ /*
+ * discard_granularity is the smallest supported unit of a
+ * discard. If that is larger than the maximum supported discard
+ * size, we need to disable discards altogether.
+ */
+ lim.discard_granularity = 0;
+ lim.max_hw_discard_sectors = 0;
}
- q->limits = common_limits;
- blk_queue_max_hw_sectors(q, common_limits.max_hw_sectors);
- decide_on_discard_support(device, bdev);
- fixup_write_zeroes(device, q);
- fixup_discard_support(device, q);
+ if (queue_limits_commit_update(q, &lim))
+ drbd_err(device, "setting new queue limits failed\n");
}
/* Make sure IO is suspended before calling this function(). */
--
2.35.3