[RFC PATCH 04/28] block: Never bounce dma-direct bios
From: Logan Gunthorpe <logang@deltatee.com>
Date: 2019-06-20 16:15:14
Also in:
linux-nvme, linux-pci, linux-rdma, lkml
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
It is expected the creator of the dma-direct bio will ensure the target device can access the DMA address it's creating bios for. It's also not possible to bounce a dma-direct bio seeing the block layer doesn't have any way to access the underlying data behind the DMA address. Thus, never bounce dma-direct bios. Signed-off-by: Logan Gunthorpe <logang@deltatee.com> --- block/bounce.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/block/bounce.c b/block/bounce.c
index f8ed677a1bf7..17e020a40cca 100644
--- a/block/bounce.c
+++ b/block/bounce.c@@ -367,6 +367,14 @@ void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig) if (!bio_has_data(*bio_orig)) return; + /* + * For DMA direct bios, Upper layers are expected to ensure + * the device in question can access the DMA addresses. So + * it never makes sense to bounce a DMA direct bio. + */ + if (bio_is_dma_direct(*bio_orig)) + return; + /* * for non-isa bounce case, just check if the bounce pfn is equal * to or bigger than the highest pfn in the system -- in that case,
--
2.20.1