48 lines
1.7 KiB
Diff
48 lines
1.7 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: Wed, 28 Jul 2021 08:55:31 +0200
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Subject: [PATCH] io_uring: don't block level reissue off completion path
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Some setups, like SCSI, can throw spurious -EAGAIN off the softirq
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completion path. Normally we expect this to happen inline as part
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of submission, but apparently SCSI has a weird corner case where it
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can happen as part of normal completions.
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This should be solved by having the -EAGAIN bubble back up the stack
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as part of submission, but previous attempts at this failed and we're
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not just quite there yet. Instead we currently use REQ_F_REISSUE to
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handle this case.
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For now, catch it in io_rw_should_reissue() and prevent a reissue
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from a bogus path.
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Upstream mail:
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https://lore.kernel.org/io-uring/20210727165811.284510-3-axboe@kernel.dk/T/#u
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Originally-by: Jens Axboe <axboe@kernel.dk>
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[backport]
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Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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---
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fs/io_uring.c | 7 +++++++
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1 file changed, 7 insertions(+)
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diff --git a/fs/io_uring.c b/fs/io_uring.c
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index b9353cf8aab9..50d1920d2536 100644
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--- a/fs/io_uring.c
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+++ b/fs/io_uring.c
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@@ -2746,6 +2746,13 @@ static bool io_rw_reissue(struct io_kiocb *req, long res)
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if (percpu_ref_is_dying(&req->ctx->refs))
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return false;
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+ /*
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+ * Play it safe and assume not safe to re-import and reissue if we're
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+ * not in the original thread group (or in task context).
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+ */
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+ if (!same_thread_group(req->task, current) || !in_task())
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+ return false;
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+
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lockdep_assert_held(&req->ctx->uring_lock);
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ret = io_sq_thread_acquire_mm_files(req->ctx, req);
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