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From: Jens Axboe <[email protected]>
To: io-uring <[email protected]>
Cc: Samuel Williams <[email protected]>
Subject: [PATCH] io_uring: zero iocb->ki_pos for stream file types
Date: Wed, 22 Dec 2021 20:36:28 -0700	[thread overview]
Message-ID: <[email protected]> (raw)

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 <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index d5ab0e9a3f29..fb2a0cb4aaf8 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2891,9 +2891,13 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		req->flags |= io_file_get_flags(file) << REQ_F_SUPPORT_NOWAIT_BIT;
 
 	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_flags = iocb_flags(file);
 	ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags));

-- 
Jens Axboe


                 reply	other threads:[~2021-12-23  3:36 UTC|newest]

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