NVMe: Create discard zero quirk white list (08095e70) · Commits · 戴 / test

The NVMe specification does not require discarded blocks return zeroes on read, but provides that behavior as a possibility. Some applications more efficiently use an SSD if reads on discarded blocks were deterministically zero, based on the "discard_zeroes_data" queue attribute. There is no specification defined way to determine device behavior on discarded blocks, so the driver always left the queue setting disabled. We can only know behavior based on individual device models, so this patch adds a flag to the NVMe "quirk" list that vendors may set if they know their controller works that way. The patch also sets the new flag for one such known device. Signed-off-by:

Keith Busch <keith.busch@intel.com> Suggested-by:

Artur Paszkiewicz <artur.paszkiewicz@intel.com> Reviewed-by:

Christoph Hellwig <hch@lst.de> Reviewed-by:

Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by:

Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by:

Sagi Grimberg <sagig@mellanox.com> Signed-off-by:

Jens Axboe <axboe@fb.com>

drivers/nvme/host/core.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -582,8 +582,14 @@ static void nvme_init_integrity(struct nvme_ns *ns)

		static void nvme_config_discard(struct nvme_ns *ns)
		{
		struct nvme_ctrl *ctrl = ns->ctrl;
		u32 logical_block_size = queue_logical_block_size(ns->queue);

		if (ctrl->quirks & NVME_QUIRK_DISCARD_ZEROES)
		ns->queue->limits.discard_zeroes_data = 1;
		else
		ns->queue->limits.discard_zeroes_data = 0;

		ns->queue->limits.discard_alignment = logical_block_size;
		ns->queue->limits.discard_granularity = logical_block_size;
		blk_queue_max_discard_sectors(ns->queue, 0xffffffff);

drivers/nvme/host/nvme.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -59,6 +59,12 @@ enum nvme_quirks {
		* correctly.
		*/
		NVME_QUIRK_IDENTIFY_CNS = (1 << 1),

		/*
		* The controller deterministically returns O's on reads to discarded
		* logical blocks.
		*/
		NVME_QUIRK_DISCARD_ZEROES = (1 << 2),
		};

		struct nvme_ctrl {

drivers/nvme/host/pci.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -2130,7 +2130,8 @@ static const struct pci_error_handlers nvme_err_handler = {

		static const struct pci_device_id nvme_id_table[] = {
		{ PCI_VDEVICE(INTEL, 0x0953),
		.driver_data = NVME_QUIRK_STRIPE_SIZE, },
		.driver_data = NVME_QUIRK_STRIPE_SIZE \|
		NVME_QUIRK_DISCARD_ZEROES, },
		{ PCI_VDEVICE(INTEL, 0x5845), /* Qemu emulated controller */
		.driver_data = NVME_QUIRK_IDENTIFY_CNS, },
		{ PCI_DEVICE_CLASS(PCI_CLASS_STORAGE_EXPRESS, 0xffffff) },

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