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io_uring: don't use retry based buffered reads for non-async bdev 

Some block devices, like dm, bubble back -EAGAIN through the completion
handler. We check for this in io_read(), but don't honor it for when
we have copied the iov. Return -EAGAIN for this case before retrying,
to force punt to io-wq.

Fixes: bcf5a06304 ("io_uring: support true async buffered reads, if file provides it")
Reported-by: Zorro Lang <zlang@redhat.com>
Tested-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2020-09-14 09:30:38 -06:00
parent 8f3d749685
commit f5cac8b156
1 changed files with 5 additions and 1 deletions
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6
fs/io_uring.c
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@ -3130,6 +3130,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
struct iov_iter __iter, *iter = &__iter;
ssize_t io_size, ret, ret2;
size_t iov_count;
bool no_async;
if (req->io)
iter = &req->io->rw.iter;
@ -3147,7 +3148,8 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
kiocb->ki_flags &= ~IOCB_NOWAIT;
/* If the file doesn't support async, just async punt */
if (force_nonblock && !io_file_supports_async(req->file, READ))
no_async = force_nonblock && !io_file_supports_async(req->file, READ);
if (no_async)
goto copy_iov;
ret = rw_verify_area(READ, req->file, io_kiocb_ppos(kiocb), iov_count);
@ -3191,6 +3193,8 @@ copy_iov:
ret = ret2;
goto out_free;
}
if (no_async)
return -EAGAIN;
/* it's copied and will be cleaned with ->io */
iovec = NULL;
/* now use our persistent iterator, if we aren't already */