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    Subject[PATCH 5.15 044/128] io_uring: zero iocb->ki_pos for stream file types
    Date
    From: Jens Axboe <axboe@kernel.dk>

    [ Upstream commit 7b9762a5e8837b92a027d58d396a9d27f6440c36 ]

    io_uring supports using offset == -1 for using the current file position,
    and we read that in as part of read/write command setup. For the non-iter
    read/write types we pass in NULL for the position pointer, but for the
    iter types we should not be passing any anything but 0 for the position
    for a stream.

    Clear kiocb->ki_pos if the file is a stream, don't leave it as -1. If we
    do, then the request will error with -ESPIPE.

    Fixes: ba04291eb66e ("io_uring: allow use of offset == -1 to mean file position")
    Link: https://github.com/axboe/liburing/discussions/501
    Reported-by: Samuel Williams <samuel.williams@oriontransfer.co.nz>
    Signed-off-by: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/io_uring.c | 10 +++++++---
    1 file changed, 7 insertions(+), 3 deletions(-)

    diff --git a/fs/io_uring.c b/fs/io_uring.c
    index e9b06e339c4b0..0006fc7479ca3 100644
    --- a/fs/io_uring.c
    +++ b/fs/io_uring.c
    @@ -2879,9 +2879,13 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
    req->flags |= REQ_F_ISREG;

    kiocb->ki_pos = READ_ONCE(sqe->off);
    - if (kiocb->ki_pos == -1 && !(file->f_mode & FMODE_STREAM)) {
    - req->flags |= REQ_F_CUR_POS;
    - kiocb->ki_pos = file->f_pos;
    + if (kiocb->ki_pos == -1) {
    + if (!(file->f_mode & FMODE_STREAM)) {
    + req->flags |= REQ_F_CUR_POS;
    + kiocb->ki_pos = file->f_pos;
    + } else {
    + kiocb->ki_pos = 0;
    + }
    }
    kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
    kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
    --
    2.34.1


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