[PATCH] io_uring_enter(2): Clarify how to read from and write to non-seekable files

[PATCH] io_uring_enter(2): Clarify how to read from and write to non-seekable files

[Alois Wohlschlager]

IORING_OP_READ* and IORING_OP_WRITE* all take a file offset. These
operations can still be used with non-seekable files, as long as the
offset is set to zero.

Signed-off-by: Alois Wohlschlager <alois1@gmx-topmail.de>
---
 man/io_uring_enter.2 | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/man/io_uring_enter.2 b/man/io_uring_enter.2
index 5b498e5..dd3c962 100644
--- a/man/io_uring_enter.2
+++ b/man/io_uring_enter.2
@@ -195,6 +195,9 @@ Vectored read and write operations, similar to
 .BR preadv2 (2)
 and
 .BR pwritev2 (2).
+If the file is not seekable,
+.I off
+must be set to zero.

 .TP
 .B IORING_OP_READ_FIXED
@@ -588,6 +591,10 @@ contains the buffer in question,
 contains the length of the IO operation, and
 .I offs
 contains the read or write offset. If
+.I fd
+does not refer to a seekable file,
+.I off
+must be set to zero. If
 .I offs
 is set to -1, the offset will use (and advance) the file position, like the
 .BR read(2)
--
2.31.1

Re: [PATCH] io_uring_enter(2): Clarify how to read from and write to non-seekable files

[Jens Axboe]

On 5/31/21 6:38 AM, Alois Wohlschlager wrote:
> IORING_OP_READ* and IORING_OP_WRITE* all take a file offset. These
> operations can still be used with non-seekable files, as long as the
> offset is set to zero.

Applied, thanks.

-- 
Jens Axboe