From 69ba1ee9360a6ed4adb3168fd93db430a4276332 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Tue, 14 Jun 2016 00:26:21 +0200 Subject: drbd: possibly disable discard support, if backend has discard_zeroes_data=0 Now that we have the discard_zeroes_if_aligned setting, we should also check it when setting up our queue parameters on the primary, not only on the receiving side. We announce discard support, UNLESS * we are connected to a peer that does not support TRIM on the DRBD protocol level. Otherwise, it would either discard, or do a fallback to zero-out, depending on its backend and configuration. * our local backend does not support discards, or (discard_zeroes_data=0 AND discard_zeroes_if_aligned=no). Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg Signed-off-by: Jens Axboe --- drivers/block/drbd/drbd_nl.c | 80 ++++++++++++++++++++++++++++++-------------- 1 file changed, 55 insertions(+), 25 deletions(-) (limited to 'drivers/block/drbd') diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c index 8d757d6f21e7..12e9b31c7d87 100644 --- a/drivers/block/drbd/drbd_nl.c +++ b/drivers/block/drbd/drbd_nl.c @@ -1154,6 +1154,59 @@ static int drbd_check_al_size(struct drbd_device *device, struct disk_conf *dc) return 0; } +static void blk_queue_discard_granularity(struct request_queue *q, unsigned int granularity) +{ + q->limits.discard_granularity = granularity; +} +static void decide_on_discard_support(struct drbd_device *device, + struct request_queue *q, + struct request_queue *b, + bool discard_zeroes_if_aligned) +{ + /* q = drbd device queue (device->rq_queue) + * b = backing device queue (device->ldev->backing_bdev->bd_disk->queue), + * or NULL if diskless + */ + struct drbd_connection *connection = first_peer_device(device)->connection; + bool can_do = b ? blk_queue_discard(b) : true; + + if (can_do && b && !b->limits.discard_zeroes_data && !discard_zeroes_if_aligned) { + can_do = false; + drbd_info(device, "discard_zeroes_data=0 and discard_zeroes_if_aligned=no: disabling discards\n"); + } + if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & FF_TRIM)) { + can_do = false; + drbd_info(connection, "peer DRBD too old, does not support TRIM: disabling discards\n"); + } + if (can_do) { + /* 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); + q->limits.max_discard_sectors = DRBD_MAX_DISCARD_SECTORS; + queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q); + } else { + queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q); + blk_queue_discard_granularity(q, 0); + q->limits.max_discard_sectors = 0; + } +} + +static void fixup_discard_if_not_supported(struct request_queue *q) +{ + /* To avoid confusion, if this queue does not support discard, clear + * max_discard_sectors, which is what lsblk -D reports to the user. + * Older kernels got this wrong in "stack limits". + * */ + if (!blk_queue_discard(q)) { + blk_queue_max_discard_sectors(q, 0); + blk_queue_discard_granularity(q, 0); + } +} + static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backing_dev *bdev, unsigned int max_bio_size) { @@ -1183,26 +1236,8 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi /* This is the workaround for "bio would need to, but cannot, be split" */ blk_queue_max_segments(q, max_segments ? max_segments : BLK_MAX_SEGMENTS); blk_queue_segment_boundary(q, PAGE_SIZE-1); - + decide_on_discard_support(device, q, b, discard_zeroes_if_aligned); 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) && (b->limits.discard_zeroes_data || discard_zeroes_if_aligned) && - (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); - } else { - blk_queue_max_discard_sectors(q, 0); - queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q); - q->limits.discard_granularity = 0; - } - blk_queue_stack_limits(q, b); if (q->backing_dev_info.ra_pages != b->backing_dev_info.ra_pages) { @@ -1212,12 +1247,7 @@ 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; - } + fixup_discard_if_not_supported(q); } void drbd_reconsider_queue_parameters(struct drbd_device *device, struct drbd_backing_dev *bdev) -- cgit v1.2.3