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block/io_uring: resubmit when result is -EAGAIN 

Linux SCSI can throw spurious -EAGAIN in some corner cases in its
completion path, which will end up being the result in the completed
io_uring request.

Resubmitting such requests should allow block jobs to complete, even
if such spurious errors are encountered.

Co-authored-by: Stefan Hajnoczi <stefanha@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
Message-id: 20210729091029.65369-1-f.ebner@proxmox.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Fabian Ebner 2021-07-29 11:10:29 +02:00 committed by Stefan Hajnoczi
parent 0ef2801423
commit 54caccb365
1 changed files with 15 additions and 1 deletions
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16
block/io_uring.c
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@ -165,7 +165,21 @@ static void luring_process_completions(LuringState *s)
total_bytes = ret + luringcb->total_read;
if (ret < 0) {
if (ret == -EINTR) {
/*
* Only writev/readv/fsync requests on regular files or host block
* devices are submitted. Therefore -EAGAIN is not expected but it's
* known to happen sometimes with Linux SCSI. Submit again and hope
* the request completes successfully.
*
* For more information, see:
* https://lore.kernel.org/io-uring/20210727165811.284510-3-axboe@kernel.dk/T/#u
*
* If the code is changed to submit other types of requests in the
* future, then this workaround may need to be extended to deal with
* genuine -EAGAIN results that should not be resubmitted
* immediately.
*/
if (ret == -EINTR || ret == -EAGAIN) {
luring_resubmit(s, luringcb);
continue;
}