Commit 5e063101 authored Oct 16, 2020 by Logan Gunthorpe Committed by Christoph Hellwig Oct 22, 2020

nvmet: cleanup nvmet_passthru_map_sg()



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: c1fef73f ("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>

parent df06047d

drivers/nvme/target/passthru.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -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);

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