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nvmet: cleanup nvmet_passthru_map_sg()

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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: c1fef73f79 ("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>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Logan Gunthorpe 2020-10-16 16:19:05 -06:00 committed by Christoph Hellwig
parent df06047d54
commit 5e063101ff
1 changed files with 4 additions and 3 deletions
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7
drivers/nvme/target/passthru.c
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@ -187,18 +187,20 @@ 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;
@ -208,7 +210,6 @@ 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);