> On 4 Mar 2019, at 15.24, Hans Holmberg <hans@xxxxxxxxxxxxx> wrote: > > On Mon, Mar 4, 2019 at 2:44 PM Javier González <javier@xxxxxxxxxxx> wrote: >>> On 4 Mar 2019, at 14.25, Matias Bjørling <mb@xxxxxxxxxxx> wrote: >>> >>> On 3/4/19 2:19 PM, Javier González wrote: >>>>> On 4 Mar 2019, at 13.22, Hans Holmberg <hans@xxxxxxxxxxxxx> wrote: >>>>> >>>>> On Mon, Mar 4, 2019 at 12:44 PM Javier González <javier@xxxxxxxxxxx> wrote: >>>>>>> On 4 Mar 2019, at 12.30, Hans Holmberg <hans@xxxxxxxxxxxxx> wrote: >>>>>>> >>>>>>> On Mon, Mar 4, 2019 at 10:05 AM Javier González <javier@xxxxxxxxxxx> wrote: >>>>>>>>> On 27 Feb 2019, at 18.14, Igor Konopko <igor.j.konopko@xxxxxxxxx> wrote: >>>>>>>>> >>>>>>>>> Current lightnvm and pblk implementation does not care >>>>>>>>> about NVMe max data transfer size, which can be smaller >>>>>>>>> than 64*K=256K. This patch fixes issues related to that. >>>>>>> >>>>>>> Could you describe *what* issues you are fixing? >>>>>>> >>>>>>>>> Signed-off-by: Igor Konopko <igor.j.konopko@xxxxxxxxx> >>>>>>>>> --- >>>>>>>>> drivers/lightnvm/core.c | 9 +++++++-- >>>>>>>>> drivers/nvme/host/lightnvm.c | 1 + >>>>>>>>> include/linux/lightnvm.h | 1 + >>>>>>>>> 3 files changed, 9 insertions(+), 2 deletions(-) >>>>>>>>> >>>>>>>>> diff --git a/drivers/lightnvm/core.c b/drivers/lightnvm/core.c >>>>>>>>> index 5f82036fe322..c01f83b8fbaf 100644 >>>>>>>>> --- a/drivers/lightnvm/core.c >>>>>>>>> +++ b/drivers/lightnvm/core.c >>>>>>>>> @@ -325,6 +325,7 @@ static int nvm_create_tgt(struct nvm_dev *dev, struct nvm_ioctl_create *create) >>>>>>>>> struct nvm_target *t; >>>>>>>>> struct nvm_tgt_dev *tgt_dev; >>>>>>>>> void *targetdata; >>>>>>>>> + unsigned int mdts; >>>>>>>>> int ret; >>>>>>>>> >>>>>>>>> switch (create->conf.type) { >>>>>>>>> @@ -412,8 +413,12 @@ static int nvm_create_tgt(struct nvm_dev *dev, struct nvm_ioctl_create *create) >>>>>>>>> tdisk->private_data = targetdata; >>>>>>>>> tqueue->queuedata = targetdata; >>>>>>>>> >>>>>>>>> - blk_queue_max_hw_sectors(tqueue, >>>>>>>>> - (dev->geo.csecs >> 9) * NVM_MAX_VLBA); >>>>>>>>> + mdts = (dev->geo.csecs >> 9) * NVM_MAX_VLBA; >>>>>>>>> + if (dev->geo.mdts) { >>>>>>>>> + mdts = min_t(u32, dev->geo.mdts, >>>>>>>>> + (dev->geo.csecs >> 9) * NVM_MAX_VLBA); >>>>>>>>> + } >>>>>>>>> + blk_queue_max_hw_sectors(tqueue, mdts); >>>>>>>>> >>>>>>>>> set_capacity(tdisk, tt->capacity(targetdata)); >>>>>>>>> add_disk(tdisk); >>>>>>>>> diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c >>>>>>>>> index b759c25c89c8..b88a39a3cbd1 100644 >>>>>>>>> --- a/drivers/nvme/host/lightnvm.c >>>>>>>>> +++ b/drivers/nvme/host/lightnvm.c >>>>>>>>> @@ -991,6 +991,7 @@ int nvme_nvm_register(struct nvme_ns *ns, char *disk_name, int node) >>>>>>>>> geo->csecs = 1 << ns->lba_shift; >>>>>>>>> geo->sos = ns->ms; >>>>>>>>> geo->ext = ns->ext; >>>>>>>>> + geo->mdts = ns->ctrl->max_hw_sectors; >>>>>>>>> >>>>>>>>> dev->q = q; >>>>>>>>> memcpy(dev->name, disk_name, DISK_NAME_LEN); >>>>>>>>> diff --git a/include/linux/lightnvm.h b/include/linux/lightnvm.h >>>>>>>>> index 5d865a5d5cdc..d3b02708e5f0 100644 >>>>>>>>> --- a/include/linux/lightnvm.h >>>>>>>>> +++ b/include/linux/lightnvm.h >>>>>>>>> @@ -358,6 +358,7 @@ struct nvm_geo { >>>>>>>>> u16 csecs; /* sector size */ >>>>>>>>> u16 sos; /* out-of-band area size */ >>>>>>>>> bool ext; /* metadata in extended data buffer */ >>>>>>>>> + u32 mdts; /* Max data transfer size*/ >>>>>>>>> >>>>>>>>> /* device write constrains */ >>>>>>>>> u32 ws_min; /* minimum write size */ >>>>>>>>> -- >>>>>>>>> 2.17.1 >>>>>>>> >>>>>>>> I see where you are going with this and I partially agree, but none of >>>>>>>> the OCSSD specs define a way to define this parameter. Thus, adding this >>>>>>>> behavior taken from NVMe in Linux can break current implementations. Is >>>>>>>> this a real life problem for you? Or this is just for NVMe “correctness”? >>>>>>>> >>>>>>>> Javier >>>>>>> >>>>>>> Hmm.Looking into the 2.0 spec what it says about vector reads: >>>>>>> >>>>>>> (figure 28):"The number of Logical Blocks (NLB): This field indicates >>>>>>> the number of logical blocks to be read. This is a 0’s based value. >>>>>>> Maximum of 64 LBAs is supported." >>>>>>> >>>>>>> You got the max limit covered, and the spec does not say anything >>>>>>> about the minimum number of LBAs to support. >>>>>>> >>>>>>> Matias: any thoughts on this? >>>>>>> >>>>>>> Javier: How would this patch break current implementations? >>>>>> >>>>>> Say an OCSSD controller that sets mdts to a value under 64 or does not >>>>>> set it at all (maybe garbage). Think you can get to one pretty quickly... >>>>> >>>>> So we cant make use of a perfectly good, standardized, parameter >>>>> because some hypothetical non-compliant device out there might not >>>>> provide a sane value? >>>> The OCSSD standard has never used NVMe parameters, so there is no >>>> compliant / non-compliant. In fact, until we changed OCSSD 2.0 to >>>> get the sector and OOB sizes from the standard identify >>>> command, we used to have them in the geometry. >>> >>> What the hell? Yes it has. The whole OCSSD spec is dependent on the >>> NVMe spec. It is using many commands from the NVMe specification, >>> which is not defined in the OCSSD specification. >> >> First, lower the tone. >> >> Second, no, it has not and never has, starting with all the write >> constrains, continuing with the vector commands, etc. You cannot choose >> what you want to be compliant with and what you do not. OCSSD uses the >> NVMe protocol but it is self sufficient with its geometry for all the >> read / write / erase paths - it even depends on different PCIe class >> codes to be identified… To do this in the way the rest of the spec is >> defined, we either add a filed to the geometry or explicitly mention >> that MDTS is used, as we do with the sector and metadata sizes. >> >> Third, as a maintainer of this subsystem you should care about devices >> in the field that might break due to such a change (supported by the >> company you work for or not) - even if you can argue whether the change >> is compliant or not. >> >> And Hans, as a representative of a company that has such devices out >> there, you should care too. > > If you worry about me doing my job, you need not to. > I test. So far I have not found any regressions in this patchset. > > Please keep your open source hat on Javier. Ok. You said it. Then please apply the patch :) Reviewed-by: Javier González <javier@xxxxxxxxxxx>
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