Commit 9dbbfab7 authored Oct 06, 2014 by Keith Busch Committed by Jens Axboe Nov 04, 2014

NVMe: Do not over allocate for discard requests



Discard requests are often for very large ranges. The discard size is not
representative of the data transfer size so we don't need to allocate
for such a large prp list. This patch requests allocating only enough
for the memory needed for the data transfer and saves a little over 8k
of memory per max discard request.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reported-by: Paul Grabinar <paul.grabinar@ranbarg.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 9e60352c

drivers/block/nvme-core.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -763,11 +763,13 @@ static int nvme_submit_bio_queue(struct nvme_queue nvmeq, struct nvme_ns ns,
		struct nvme_iod *iod;
		int psegs = bio_phys_segments(ns->queue, bio);
		int result;
		unsigned size = !(bio->bi_rw & REQ_DISCARD) ? bio->bi_iter.bi_size :
		sizeof(struct nvme_dsm_range);

		if ((bio->bi_rw & REQ_FLUSH) && psegs)
		return nvme_split_flush_data(nvmeq, bio);

		iod = nvme_alloc_iod(psegs, bio->bi_iter.bi_size, ns->dev, GFP_ATOMIC);
		iod = nvme_alloc_iod(psegs, size, ns->dev, GFP_ATOMIC);
		if (!iod)
		return -ENOMEM;

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