* [PATCH v3 1/2] nvmet-passthru: Limit mdts by BIO_MAX_PAGES
@ 2020-10-19 22:04 Logan Gunthorpe
2020-10-19 22:04 ` [PATCH v3 2/2] nvmet-passthru: Cleanup nvmet_passthru_map_sg() Logan Gunthorpe
2020-10-20 8:18 ` [PATCH v3 1/2] nvmet-passthru: Limit mdts by BIO_MAX_PAGES Sagi Grimberg
0 siblings, 2 replies; 3+ messages in thread
From: Logan Gunthorpe @ 2020-10-19 22:04 UTC (permalink / raw)
To: linux-nvme
Cc: Max Gurtovoy, Logan Gunthorpe, Christoph Hellwig,
Chaitanya Kulkarni, Sagi Grimberg
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>
Cc: Max Gurtovoy <mgurtovoy@nvidia.com>
---
v3: Added PG_TO_SECTOR constant which uses SECTOR_SHIFT (per Max)
drivers/nvme/target/passthru.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index dacfa7435d0b..ed6b0586173e 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -22,11 +22,12 @@ static DEFINE_XARRAY(passthru_subsystems);
static u16 nvmet_passthru_override_id_ctrl(struct nvmet_req *req)
{
+ const int PG_TO_SECTOR = PAGE_SHIFT - SECTOR_SHIFT;
struct nvmet_ctrl *ctrl = req->sq->ctrl;
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);
@@ -45,9 +46,16 @@ static u16 nvmet_passthru_override_id_ctrl(struct nvmet_req *req)
* which depends on the host's memory fragementation. To solve this,
* ensure mdts is limited to the pages equal to the number of segments.
*/
- max_hw_sectors = min_not_zero(pctrl->max_segments << (PAGE_SHIFT - 9),
+ max_hw_sectors = min_not_zero(pctrl->max_segments << PG_TO_SECTOR,
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 << PG_TO_SECTOR,
+ max_hw_sectors);
+
page_shift = NVME_CAP_MPSMIN(ctrl->cap) + 12;
id->mdts = ilog2(max_hw_sectors) + 9 - page_shift;
base-commit: bbf5c979011a099af5dc76498918ed7df445635b
--
2.20.1
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH v3 2/2] nvmet-passthru: Cleanup nvmet_passthru_map_sg()
2020-10-19 22:04 [PATCH v3 1/2] nvmet-passthru: Limit mdts by BIO_MAX_PAGES Logan Gunthorpe
@ 2020-10-19 22:04 ` Logan Gunthorpe
2020-10-20 8:18 ` [PATCH v3 1/2] nvmet-passthru: Limit mdts by BIO_MAX_PAGES Sagi Grimberg
1 sibling, 0 replies; 3+ messages in thread
From: Logan Gunthorpe @ 2020-10-19 22:04 UTC (permalink / raw)
To: linux-nvme
Cc: Christoph Hellwig, Logan Gunthorpe, Sagi Grimberg,
Chaitanya Kulkarni, Douglas Gilbert
Clean up some confusing elements of nvmet_passthru_map_sg() by returning
early if the request is greater than the maximum bio size. This allows
us to drop the sg_cnt variable.
This should not result in any functional change but makes the code
clearer and more understandable. The original code allocated a truncated
bio then would return EINVAL when bio_add_pc_page() filled that bio. The
new code just returns EINVAL early if this would happen.
Fixes: c1fef73f793b ("nvmet: add passthru code to process commands")
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Suggested-by: Douglas Gilbert <dgilbert@interlog.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
drivers/nvme/target/passthru.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index ed6b0586173e..0e891a286fd8 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -188,18 +188,20 @@ static void nvmet_passthru_req_done(struct request *rq,
static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
{
- int sg_cnt = req->sg_cnt;
struct scatterlist *sg;
int op_flags = 0;
struct bio *bio;
int i, ret;
+ if (req->sg_cnt > BIO_MAX_PAGES)
+ return -EINVAL;
+
if (req->cmd->common.opcode == nvme_cmd_flush)
op_flags = REQ_FUA;
else if (nvme_is_write(req->cmd))
op_flags = REQ_SYNC | REQ_IDLE;
- bio = bio_alloc(GFP_KERNEL, min(sg_cnt, BIO_MAX_PAGES));
+ bio = bio_alloc(GFP_KERNEL, req->sg_cnt);
bio->bi_end_io = bio_put;
bio->bi_opf = req_op(rq) | op_flags;
@@ -209,7 +211,6 @@ static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
bio_put(bio);
return -EINVAL;
}
- sg_cnt--;
}
ret = blk_rq_append_bio(rq, &bio);
--
2.20.1
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http://lists.infradead.org/mailman/listinfo/linux-nvme
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3 1/2] nvmet-passthru: Limit mdts by BIO_MAX_PAGES
2020-10-19 22:04 [PATCH v3 1/2] nvmet-passthru: Limit mdts by BIO_MAX_PAGES Logan Gunthorpe
2020-10-19 22:04 ` [PATCH v3 2/2] nvmet-passthru: Cleanup nvmet_passthru_map_sg() Logan Gunthorpe
@ 2020-10-20 8:18 ` Sagi Grimberg
1 sibling, 0 replies; 3+ messages in thread
From: Sagi Grimberg @ 2020-10-20 8:18 UTC (permalink / raw)
To: Logan Gunthorpe, linux-nvme
Cc: Max Gurtovoy, Christoph Hellwig, Chaitanya Kulkarni
> diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
> index dacfa7435d0b..ed6b0586173e 100644
> --- a/drivers/nvme/target/passthru.c
> +++ b/drivers/nvme/target/passthru.c
> @@ -22,11 +22,12 @@ static DEFINE_XARRAY(passthru_subsystems);
>
> static u16 nvmet_passthru_override_id_ctrl(struct nvmet_req *req)
> {
> + const int PG_TO_SECTOR = PAGE_SHIFT - SECTOR_SHIFT;
> struct nvmet_ctrl *ctrl = req->sq->ctrl;
> 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);
> @@ -45,9 +46,16 @@ static u16 nvmet_passthru_override_id_ctrl(struct nvmet_req *req)
> * which depends on the host's memory fragementation. To solve this,
> * ensure mdts is limited to the pages equal to the number of segments.
> */
> - max_hw_sectors = min_not_zero(pctrl->max_segments << (PAGE_SHIFT - 9),
> + max_hw_sectors = min_not_zero(pctrl->max_segments << PG_TO_SECTOR,
> pctrl->max_hw_sectors);
I also liked the previous one better...
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http://lists.infradead.org/mailman/listinfo/linux-nvme
^ permalink raw reply [flat|nested] 3+ messages in thread
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