From 3ec5c62cfcf060e9ea533cd3901f5d03b26ddc24 Mon Sep 17 00:00:00 2001 From: Guixin Liu Date: Mon, 9 Dec 2024 09:53:44 +0800 Subject: [PATCH] nvmet: handle rw's limited retry flag In some scenarios, some multipath software setup places the REQ_FAILFAST_DEV flag on I/O to prevent retries and immediately switch to other paths for issuing I/O commands. This will reflect on the NVMe read and write commands with the limited retry flag. However, the current NVMe target side does not handle the limited retry flag, and the target's underlying driver still retries the I/O. This will result in the I/O not being quickly switched to other paths, ultimately leading to increased I/O latency. When the nvme target receive an rw command with limited retry flag, handle it in block backend by setting the REQ_FAILFAST_DEV flag to bio. Signed-off-by: Guixin Liu Reviewed-by: Chaitanya Kulkarni Reviewed-by: Christoph Hellwig Reviewed-by: Sagi Grimberg Signed-off-by: Keith Busch --- drivers/nvme/target/io-cmd-bdev.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c index 0bda83d0fc3e0..6380b60fd4900 100644 --- a/drivers/nvme/target/io-cmd-bdev.c +++ b/drivers/nvme/target/io-cmd-bdev.c @@ -272,6 +272,9 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req) iter_flags = SG_MITER_FROM_SG; } + if (req->cmd->rw.control & NVME_RW_LR) + opf |= REQ_FAILFAST_DEV; + if (is_pci_p2pdma_page(sg_page(req->sg))) opf |= REQ_NOMERGE;