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nvme: implement the DEAC bit for the Write Zeroes command 

While the specification allows devices to either deallocate data
or to actually write zeroes on any Write Zeroes command, many SSDs
only do the sensible thing and deallocate data when the DEAC bit
is specific.  Set it when it is supported and the caller doesn't
explicitly opt out of deallocation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Christoph Hellwig 2022-10-30 16:50:15 +01:00
parent e4fbcf32c8
commit 1b96f862ec
3 changed files with 14 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/nvme/host/core.c
View File

@ -850,8 +850,11 @@ static inline blk_status_t nvme_setup_write_zeroes(struct nvme_ns *ns,
cmnd->write_zeroes.length =
cpu_to_le16((blk_rq_bytes(req) >> ns->lba_shift) - 1);
if (!(req->cmd_flags & REQ_NOUNMAP) && (ns->features & NVME_NS_DEAC))
cmnd->write_zeroes.control |= cpu_to_le16(NVME_WZ_DEAC);
if (nvme_ns_has_pi(ns)) {
cmnd->write_zeroes.control = cpu_to_le16(NVME_RW_PRINFO_PRACT);
cmnd->write_zeroes.control |= cpu_to_le16(NVME_RW_PRINFO_PRACT);
switch (ns->pi_type) {
case NVME_NS_DPS_PI_TYPE1:
@ -2003,6 +2006,14 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
}
}
/*
* Only set the DEAC bit if the device guarantees that reads from
* deallocated data return zeroes. While the DEAC bit does not
* require that, it must be a no-op if reads from deallocated data
* do not return zeroes.
*/
if ((id->dlfeat & 0x7) == 0x1 && (id->dlfeat & (1 << 3)))
ns->features |= NVME_NS_DEAC;
set_disk_ro(ns->disk, nvme_ns_is_readonly(ns, info));
set_bit(NVME_NS_READY, &ns->flags);
blk_mq_unfreeze_queue(ns->disk->queue);

1
drivers/nvme/host/nvme.h
View File

@ -455,6 +455,7 @@ static inline bool nvme_ns_head_multipath(struct nvme_ns_head *head)
enum nvme_ns_features {
NVME_NS_EXT_LBAS = 1 << 0, /* support extended LBA format */
NVME_NS_METADATA_SUPPORTED = 1 << 1, /* support getting generated md */
NVME_NS_DEAC, /* DEAC bit in Write Zeores supported */
};
struct nvme_ns {

1
include/linux/nvme.h
View File

@ -964,6 +964,7 @@ enum {
NVME_RW_PRINFO_PRCHK_GUARD = 1 << 12,
NVME_RW_PRINFO_PRACT = 1 << 13,
NVME_RW_DTYPE_STREAMS = 1 << 4,
NVME_WZ_DEAC = 1 << 9,
};
struct nvme_dsm_cmd {