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NAME | SYNOPSIS | DESCRIPTION | NOTES | RETURN VALUE | SEE ALSO | COLOPHON |
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io_uring_clone_buffers(3) liburing Manual io_uring_clone_buffers(3)
io_uring_clone_buffers - Clones registered buffers between rings
#include <liburing.h>
int io_uring_clone_buffers(struct io_uring *dst,
struct io_uring * src);
int __io_uring_clone_buffers(struct io_uring *dst,
struct io_uring * src,
unsigned int flags);
int io_uring_clone_buffers_offset(struct io_uring *dst,
struct io_uring * src,
unsigned int dst_off,
unsigned int src_off,
unsigned int nr,
unsigned int flags);
int __io_uring_clone_buffers_offset(struct io_uring *dst,
struct io_uring * src,
unsigned int dst_off,
unsigned int src_off,
unsigned int nr,
unsigned int flags);
The io_uring_clone_buffers(3) function clones registered buffers
from the ring indicated by src to the ring indicated by dst. Upon
successful completion of this operation, src and dst will have the
same set of registered buffers. This operation is identical to
performing a io_uring_register_buffers(3) operation on the dst
ring, if the src ring previously had that same buffer registration
operating done.
The dst ring must not have any buffers currently registered. If
buffers are currently registered on the destination ring, they
must be unregistered with io_uring_unregister_buffers(3) first.
For __io_uring_clone_buffers(3), the only difference is that it
takes a flags argument. By default, if the destination ring has a
registered file descriptor through io_uring_register_ring_fd(3)
AND the calling application is not the thread that registered that
ring, then the kernel doesn't know how to look up the destination.
This is problematic as io_uring_clone_buffers(3) defaults to using
the registered index if the destination is setup as such. Use
__io_uring_clone_buffers(3) which doesn't set
IORING_REGISTER_SRC_REGISTERED by default. This requires the
application to still have the original ring file descriptor open.
See below for the flag definition.
Available since kernel 6.12.
The io_uring_clone_buffers_offset(3) function also clones buffers
from the src ring to the dst ring, however it supports cloning
only a subset of the buffers, where io_uring_clone_buffers(3)
always clones all of them. dst_off indicates at what offset
cloning should start in the destination, src_off indicates at what
offset cloning should start in the source, and nr indicates how
many buffers to clone at the given offset. If both dst_off,
src_off, and nr are given as 0 , then
io_uring_clone_buffers_offset(3) performs the same action as
io_uring_clone_buffers(3).
While io_uring_clone_buffers_offset(3) sets
IORING_REGISTER_SRC_REGISTERED by default, the
__io_uring_clone_buffers_offset(3) does not. See the explanation
for __io_uring_clone_buffers(3) for details.
flags may be set to the following value:
IORING_REGISTER_SRC_REGISTERED
If the source ring is registered AND the calling thread is
the one that originally registered its ring fd, then this
flag may be set to lookup the registered index rather than
use the normal file descriptor. If the normal file
descriptor wasn't closed after registering it, there's no
need to set this flag.
IORING_REGISTER_DST_REPLACE
If set, cloning may happen for a destination ring that
already has a buffer table assigned. In that case, existing
nodes that overlap with the specified range will be
released and replaced.IORING_REGISTER_DST_REPLACE If set,
cloning may happen for a destination ring that already has
a buffer table assigned. In that case, existing nodes that
overlap with the specified range will be released and
replaced.
Available since kernel 6.13.
The source and target ring must shared address spaces, and hence
internal kernel accounting.
On success io_uring_clone_buffers(3) and
io_uring_clone_buffers_offset(3) return 0. On failure, they
returns -errno, specifically
-EBUSY The destination ring already has buffers registered, and
IORING_REGISTER_DST_REPLACE wasn't set.
-ENOMEM
The kernel ran out of memory.
-ENXIO The source ring doesn't have any buffers registered.
io_uring_register(2), io_uring_unregister_buffers(3),
io_uring_register_buffers(3), io_uring_prep_read_fixed(3),
io_uring_prep_write_fixed(3)
This page is part of the liburing (A library for io_uring)
project. Information about the project can be found at
⟨https://github.com/axboe/liburing⟩. If you have a bug report for
this manual page, send it to io-uring@vger.kernel.org. This page
was obtained from the project's upstream Git repository
⟨https://github.com/axboe/liburing⟩ on 2025-08-11. (At that time,
the date of the most recent commit that was found in the
repository was 2025-08-02.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
liburing-2.9 September 12, 2024 io_uring_clone_buffers(3)
Pages that refer to this page: io_uring_clone_buffers(3), io_uring_clone_buffers_offset(3), io_uring_register_buffers(3), io_uring_register_buffers_sparse(3), io_uring_register_buffers_tags(3), io_uring_register_buffers_update_tag(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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