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io_uring: move reissue into regular IO path
It's non-obvious how retry is done for block backed files, when it happens off the kiocb done path. It also makes it tricky to deal with the iov_iter handling. Just mark the req as needing a reissue, and handling it from the submission path instead. This makes it directly obvious that we're not re-importing the iovec from userspace past the submit point, and it means that we can just reuse our usual -EAGAIN retry path from the read/write handling. At some point in the future, we'll gain the ability to always reliably return -EAGAIN through the stack. A previous attempt on the block side didn't pan out and got reverted, hence the need to check for this information out-of-band right now. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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07204f2157
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230d50d448
1 changed files with 13 additions and 4 deletions
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@ -697,6 +697,7 @@ enum {
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REQ_F_NO_FILE_TABLE_BIT,
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REQ_F_LTIMEOUT_ACTIVE_BIT,
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REQ_F_COMPLETE_INLINE_BIT,
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REQ_F_REISSUE_BIT,
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/* not a real bit, just to check we're not overflowing the space */
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__REQ_F_LAST_BIT,
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@ -740,6 +741,8 @@ enum {
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REQ_F_LTIMEOUT_ACTIVE = BIT(REQ_F_LTIMEOUT_ACTIVE_BIT),
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/* completion is deferred through io_comp_state */
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REQ_F_COMPLETE_INLINE = BIT(REQ_F_COMPLETE_INLINE_BIT),
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/* caller should reissue async */
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REQ_F_REISSUE = BIT(REQ_F_REISSUE_BIT),
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};
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struct async_poll {
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@ -2503,8 +2506,10 @@ static void __io_complete_rw(struct io_kiocb *req, long res, long res2,
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if (req->rw.kiocb.ki_flags & IOCB_WRITE)
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kiocb_end_write(req);
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if ((res == -EAGAIN || res == -EOPNOTSUPP) && io_rw_reissue(req))
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if ((res == -EAGAIN || res == -EOPNOTSUPP) && io_rw_should_reissue(req)) {
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req->flags |= REQ_F_REISSUE;
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return;
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}
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if (res != req->result)
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req_set_fail_links(req);
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if (req->flags & REQ_F_BUFFER_SELECTED)
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@ -3283,9 +3288,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
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ret = io_iter_do_read(req, iter);
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if (ret == -EIOCBQUEUED) {
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goto out_free;
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} else if (ret == -EAGAIN) {
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if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
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/* IOPOLL retry should happen for io-wq threads */
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if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
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goto done;
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@ -3295,6 +3298,8 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
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/* some cases will consume bytes even on error returns */
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iov_iter_revert(iter, io_size - iov_iter_count(iter));
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ret = 0;
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} else if (ret == -EIOCBQUEUED) {
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goto out_free;
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} else if (ret <= 0 || ret == io_size || !force_nonblock ||
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(req->flags & REQ_F_NOWAIT) || !(req->flags & REQ_F_ISREG)) {
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/* read all, failed, already did sync or don't want to retry */
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@ -3407,6 +3412,9 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
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else
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ret2 = -EINVAL;
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if (req->flags & REQ_F_REISSUE)
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ret2 = -EAGAIN;
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/*
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* Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just
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* retry them without IOCB_NOWAIT.
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@ -6160,6 +6168,7 @@ static void io_wq_submit_work(struct io_wq_work *work)
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ret = -ECANCELED;
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if (!ret) {
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req->flags &= ~REQ_F_REISSUE;
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do {
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ret = io_issue_sqe(req, 0);
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/*
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