From mboxrd@z Thu Jan 1 00:00:00 1970 From: axboe@kernel.dk (Jens Axboe) Date: Wed, 2 May 2018 10:41:03 -0600 Subject: [PATCH] nvme: configure discard at init time In-Reply-To: <20180502163258.GI5938@localhost.localdomain> References: <20180502163258.GI5938@localhost.localdomain> Message-ID: <42987d9b-7e55-940c-79a3-c0454358d342@kernel.dk> On 5/2/18 10:32 AM, Keith Busch wrote: > On Wed, May 02, 2018@09:52:07AM -0600, Jens Axboe wrote: >> Currently nvme reconfigures discard for every disk revalidation. This >> is problematic because any O_WRONLY or O_RDWR open will trigger a >> partition scan through udev/systemd, and we will reconfigure discard. >> This blows away any user settings, like discard_max_bytes. >> >> Configure discard at init time instead. >> >> Signed-off-by: Jens Axboe >> >> --- >> >> I'm open to other suggestions as well, currently it sucks that you'd >> have to continually re-configure the discard settings when someone opens >> the device for writing. > > Your suggestion is probably fine. The only problem I can think of is a > _very_ unlikely scenario where a firmware update adds discard support, > then a user would have to reload the module in order to expose the > capability. > > How about this? If we add discard through a firmware upgrade, we should also handle the case where we lose discard through a firmware upgrade/downgrade. Not that any of them are likely to ever happen, but... How about this? Also handles the case where streams values are updated. diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 9df4f71e58ca..b0c1f1ce8226 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -1347,13 +1347,19 @@ static void nvme_set_chunk_size(struct nvme_ns *ns) blk_queue_chunk_sectors(ns->queue, rounddown_pow_of_two(chunk_size)); } -static void nvme_config_discard(struct nvme_ctrl *ctrl, - unsigned stream_alignment, struct request_queue *queue) +static void nvme_config_discard(struct nvme_ns *ns) { + struct nvme_ctrl *ctrl = ns->ctrl; + struct request_queue *queue = ns->queue; u32 size = queue_logical_block_size(queue); - if (stream_alignment) - size *= stream_alignment; + if (!(ctrl->oncs & NVME_CTRL_ONCS_DSM)) { + blk_queue_flag_clear(QUEUE_FLAG_DISCARD, queue); + return; + } + + if (ctrl->nr_streams && ns->sws && ns->sgs) + size *= ns->sws * ns->sgs; BUILD_BUG_ON(PAGE_SIZE / sizeof(struct nvme_dsm_range) < NVME_DSM_MAX_RANGES); @@ -1361,6 +1367,10 @@ static void nvme_config_discard(struct nvme_ctrl *ctrl, queue->limits.discard_alignment = 0; queue->limits.discard_granularity = size; + /* If discard is already enabled, don't reset queue limits */ + if (blk_queue_flag_test_and_set(QUEUE_FLAG_DISCARD, queue)) + return; + blk_queue_max_discard_sectors(queue, UINT_MAX); blk_queue_max_discard_segments(queue, NVME_DSM_MAX_RANGES); blk_queue_flag_set(QUEUE_FLAG_DISCARD, queue); @@ -1407,10 +1417,6 @@ static void nvme_update_disk_info(struct gendisk *disk, { sector_t capacity = le64_to_cpup(&id->nsze) << (ns->lba_shift - 9); unsigned short bs = 1 << ns->lba_shift; - unsigned stream_alignment = 0; - - if (ns->ctrl->nr_streams && ns->sws && ns->sgs) - stream_alignment = ns->sws * ns->sgs; blk_mq_freeze_queue(disk->queue); blk_integrity_unregister(disk); @@ -1427,7 +1433,7 @@ static void nvme_update_disk_info(struct gendisk *disk, set_capacity(disk, capacity); if (ns->ctrl->oncs & NVME_CTRL_ONCS_DSM) - nvme_config_discard(ns->ctrl, stream_alignment, disk->queue); + nvme_config_discard(ns); blk_mq_unfreeze_queue(disk->queue); } -- Jens Axboe