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io_uring: allow O_NONBLOCK async retry

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We can assume that O_NONBLOCK is always honored, even if we don't
have a ->read/write_iter() for the file type. Also unify the read/write
checking for allowing async punt, having the write side factoring in the
REQ_F_NOWAIT flag as well.

Cc: stable@vger.kernel.org
Fixes: 490e89676a ("io_uring: only force async punt if poll based retry can't handle it")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2020-06-09 19:23:05 -06:00
parent f5fa38c59c
commit c5b856255c
1 changed files with 7 additions and 3 deletions
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10
fs/io_uring.c
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@ -2061,6 +2061,10 @@ static bool io_file_supports_async(struct file *file, int rw)
if (S_ISREG(mode) && file->f_op != &io_uring_fops)
return true;
/* any ->read/write should understand O_NONBLOCK */
if (file->f_flags & O_NONBLOCK)
return true;
if (!(file->f_mode & FMODE_NOWAIT))
return false;
@ -2103,8 +2107,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
kiocb->ki_ioprio = get_current_ioprio();
/* don't allow async punt if RWF_NOWAIT was requested */
if ((kiocb->ki_flags & IOCB_NOWAIT) ||
(req->file->f_flags & O_NONBLOCK))
if (kiocb->ki_flags & IOCB_NOWAIT)
req->flags |= REQ_F_NOWAIT;
if (force_nonblock)
@ -2745,7 +2748,8 @@ copy_iov:
if (ret)
goto out_free;
/* any defer here is final, must blocking retry */
if (!file_can_poll(req->file))
if (!(req->flags & REQ_F_NOWAIT) &&
!file_can_poll(req->file))
req->flags |= REQ_F_MUST_PUNT;
return -EAGAIN;
}