| Message ID | 20241008145503.987195-3-m@bjorling.me (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | nvme: add rotational support | expand |
On 10/8/24 16:55, Matias Bjørling wrote: > From: Matias Bjørling <matias.bjorling@wdc.com> > > Rotational devices, such as hard-drives, can be detected using > the rotational bit in the namespace independent identify namespace > data structure. Make the bit visible to the block layer through the > rotational queue setting. > > Note that rotational devices typically can be used to generate random > entropy, the device is therefore also added as a block device that adds > entropy. > > Signed-off-by: Matias Bjørling <matias.bjorling@wdc.com> > --- > drivers/nvme/host/core.c | 5 +++++ > include/linux/nvme.h | 1 + > 2 files changed, 6 insertions(+) > Reviewed-by: Hannes Reinecke <hare@suse.de> Cheers, Hannes
On Tue, Oct 08, 2024 at 04:55:03PM +0200, Matias Bjørling wrote: > + if (info->is_rotational) > + lim.features |= BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM; Entropy from block devices is pretty useless. The only reason we still keep it for SCSI is because of retro-computing platforms without a proper platform hardware RNG. NVMe HDDs reall should not show up in those kinds of environments. Also without a add_disk_randomness in the nvme I/O completion handler this won't actually do anything.
On 09-10-2024 09:48, Christoph Hellwig wrote: > On Tue, Oct 08, 2024 at 04:55:03PM +0200, Matias Bjørling wrote: >> + if (info->is_rotational) >> + lim.features |= BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM; > > Entropy from block devices is pretty useless. The only reason we still > keep it for SCSI is because of retro-computing platforms without a proper > platform hardware RNG. NVMe HDDs reall should not show up in those kinds > of environments. Also without a add_disk_randomness in the nvme I/O > completion handler this won't actually do anything. > Thanks for the details. I'll remove it in the next revision.
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 9cbef6342c39..a445f13f5a28 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -41,6 +41,7 @@ struct nvme_ns_info { bool is_readonly; bool is_ready; bool is_removed; + bool is_rotational; }; unsigned int admin_timeout = 60; @@ -1623,6 +1624,7 @@ static int nvme_ns_info_from_id_cs_indep(struct nvme_ctrl *ctrl, info->is_shared = id->nmic & NVME_NS_NMIC_SHARED; info->is_readonly = id->nsattr & NVME_NS_ATTR_RO; info->is_ready = id->nstat & NVME_NSTAT_NRDY; + info->is_rotational = id->nsfeat & NVME_NS_ROTATIONAL; } kfree(id); return ret; @@ -2170,6 +2172,9 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns, else lim.features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA); + if (info->is_rotational) + lim.features |= BLK_FEAT_ROTATIONAL | BLK_FEAT_ADD_RANDOM; + /* * Register a metadata profile for PI, or the plain non-integrity NVMe * metadata masquerading as Type 0 if supported, otherwise reject block diff --git a/include/linux/nvme.h b/include/linux/nvme.h index 7b2ae2e43544..6d0eebb57544 100644 --- a/include/linux/nvme.h +++ b/include/linux/nvme.h @@ -560,6 +560,7 @@ enum { NVME_NS_FLBAS_LBA_SHIFT = 1, NVME_NS_FLBAS_META_EXT = 0x10, NVME_NS_NMIC_SHARED = 1 << 0, + NVME_NS_ROTATIONAL = 1 << 4, NVME_LBAF_RP_BEST = 0, NVME_LBAF_RP_BETTER = 1, NVME_LBAF_RP_GOOD = 2,