From 36e472ed229fd789f5886cc2e8c659d0cbfce817 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 1 Nov 2024 13:21:57 -0600 Subject: [PATCH] man/io_uring_register.2: document IORING_REGISTER_CLONE_BUFFERS Signed-off-by: Jens Axboe --- man/io_uring_register.2 | 60 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 59 insertions(+), 1 deletion(-) diff --git a/man/io_uring_register.2 b/man/io_uring_register.2 index 20b4baf47..c398c7c33 100644 --- a/man/io_uring_register.2 +++ b/man/io_uring_register.2 @@ -839,8 +839,66 @@ Available since 6.12 and supports and .BR CLOCK_BOOTTIME . -.SH RETURN VALUE +.TP +.B IORING_REGISTER_CLONE_BUFFERS +Supports cloning buffers from a source ring to a destination ring, duplicating +previously registered buffers from source to destination. +.IR arg +must be set to a pointer to a +.I struct io_uring_clone_buffers +and +.IR nr_args +must be set to +.B 1 . +.I struct io_uring_buf_reg +looks as follows: +.PP +.in +12n +.EX +struct io_uring_clone_buffers { + __u32 src_fd; + __u32 flags; + __u32 src_off; + __u32 dst_off; + __u32 nr; + __u32 pad[3]; +}; +.EE +.in +.TP +.PP +where +.IR src_fd +indicates the fd of the source ring, +.IR flags +are modifier flags for the operation, +.IR src_off +indicates the offset from where to start the cloning from the source ring, +.IR dst_off +indicates the offset from where to start the cloning into the destination ring, +and +.IR nr +indicates the number of buffers to clone at the given offsets. +.IR pad +must be zero filled. +Kernel 6.12 added support for full range cloning, where +.IR src_off , +.IR dst_off , +and +.IR nr +must all be set to 0, indicating cloning of the entire table in source to +destination. Kernel 6.13 added support for specifying the offsets and +how many buffers to clone. Additionally, it added support for cloning into +a previously registered table in the destination as well, 6.12 would fail +that operation with +.B -EBUSY +if attempted. To replace existing nodes, or clone into an existing table, +.B IORING_REGISTER_DST_REPLACE +must be set in the +.IR flags +member. +.SH RETURN VALUE On success, .BR io_uring_register (2) returns either 0 or a positive value, depending on the