50 lines
1.9 KiB
Diff
50 lines
1.9 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Fabian Ebner <f.ebner@proxmox.com>
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Date: Fri, 23 Jul 2021 12:42:23 +0200
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Subject: [PATCH] block/io_uring: resubmit when result is -EAGAIN
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Linux SCSI can throw spurious -EAGAIN in some corner cases in its
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completion path, which will end up being the result in the completed
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io_uring request.
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Resubmitting such requests should allow block jobs to complete, even
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if such spurious errors are encountered.
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Co-authored-by: Stefan Hajnoczi <stefanha@gmail.com>
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Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
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Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
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---
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block/io_uring.c | 16 +++++++++++++++-
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1 file changed, 15 insertions(+), 1 deletion(-)
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diff --git a/block/io_uring.c b/block/io_uring.c
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index 00a3ee9fb8..dfa475cc87 100644
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--- a/block/io_uring.c
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+++ b/block/io_uring.c
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@@ -165,7 +165,21 @@ static void luring_process_completions(LuringState *s)
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total_bytes = ret + luringcb->total_read;
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if (ret < 0) {
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- if (ret == -EINTR) {
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+ /*
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+ * Only writev/readv/fsync requests on regular files or host block
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+ * devices are submitted. Therefore -EAGAIN is not expected but it's
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+ * known to happen sometimes with Linux SCSI. Submit again and hope
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+ * the request completes successfully.
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+ *
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+ * For more information, see:
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+ * https://lore.kernel.org/io-uring/20210727165811.284510-3-axboe@kernel.dk/T/#u
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+ *
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+ * If the code is changed to submit other types of requests in the
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+ * future, then this workaround may need to be extended to deal with
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+ * genuine -EAGAIN results that should not be resubmitted
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+ * immediately.
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+ */
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+ if (ret == -EINTR || ret == -EAGAIN) {
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luring_resubmit(s, luringcb);
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continue;
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}
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--
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2.30.2
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