From: Max Gurtovoy <mgurtovoy@nvidia.com>
To: Logan Gunthorpe <logang@deltatee.com>, <linux-nvme@lists.infradead.org>
Cc: Christoph Hellwig <hch@lst.de>,
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>,
Sagi Grimberg <sagi@grimberg.me>
Subject: Re: [PATCH v2 1/2] nvmet-passthru: Limit mdts by BIO_MAX_PAGES
Date: Mon, 19 Oct 2020 14:20:52 +0300 [thread overview]
Message-ID: <7fbd6b56-cda5-a9b3-7323-99d9704fbec5@nvidia.com> (raw)
In-Reply-To: <20201016221905.4686-1-logang@deltatee.com>
On 10/17/2020 1:19 AM, Logan Gunthorpe wrote:
> nvmet_passthru_map_sg() only supports mapping a single BIO, not a chain
> so the effective maximum transfer should also be limitted by BIO_MAX_PAGES
> (presently this works out to 1MB).
>
> For PCI passthru devices the max_sectors would typically be more limitting
> than BIO_MAX_PAGES, but this may not be true for all passthru devices.
>
> Fixes: c1fef73f793b ("nvmet: add passthru code to process commands")
> Suggested-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Sagi Grimberg <sagi@grimberg.me>
> Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
> ---
> drivers/nvme/target/passthru.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
> index dacfa7435d0b..1ab88df3310f 100644
> --- a/drivers/nvme/target/passthru.c
> +++ b/drivers/nvme/target/passthru.c
> @@ -26,7 +26,7 @@ static u16 nvmet_passthru_override_id_ctrl(struct nvmet_req *req)
> struct nvme_ctrl *pctrl = ctrl->subsys->passthru_ctrl;
> u16 status = NVME_SC_SUCCESS;
> struct nvme_id_ctrl *id;
> - u32 max_hw_sectors;
> + int max_hw_sectors;
> int page_shift;
>
> id = kzalloc(sizeof(*id), GFP_KERNEL);
> @@ -48,6 +48,13 @@ static u16 nvmet_passthru_override_id_ctrl(struct nvmet_req *req)
> max_hw_sectors = min_not_zero(pctrl->max_segments << (PAGE_SHIFT - 9),
> pctrl->max_hw_sectors);
>
> + /*
> + * nvmet_passthru_map_sg is limitted to using a single bio so limit
> + * the mdts based on BIO_MAX_PAGES as well
> + */
> + max_hw_sectors = min_not_zero(BIO_MAX_PAGES << (PAGE_SHIFT - 9),
> + max_hw_sectors);
can 9 be replaced with SECTOR_SHIFT ?
> +
> page_shift = NVME_CAP_MPSMIN(ctrl->cap) + 12;
>
> id->mdts = ilog2(max_hw_sectors) + 9 - page_shift;
>
> base-commit: bbf5c979011a099af5dc76498918ed7df445635b
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next prev parent reply other threads:[~2020-10-19 11:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-16 22:19 [PATCH v2 1/2] nvmet-passthru: Limit mdts by BIO_MAX_PAGES Logan Gunthorpe
2020-10-16 22:19 ` [PATCH v2 2/2] nvmet-passthru: Cleanup nvmet_passthru_map_sg() Logan Gunthorpe
2020-10-19 11:20 ` Max Gurtovoy [this message]
2020-10-19 15:40 ` [PATCH v2 1/2] nvmet-passthru: Limit mdts by BIO_MAX_PAGES Logan Gunthorpe
[not found] ` <BYAPR04MB4965B1360F5F6A1D13FF1DD0861F0@BYAPR04MB4965.namprd04.prod.outlook.com>
2020-10-20 2:05 ` Logan Gunthorpe
2020-10-22 13:29 ` Christoph Hellwig
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