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io_uring_clone_buffers(3) — Linux manual page

io_uring_clone_buffers(3)    liburing Manualio_uring_clone_buffers(3)

NAME        top

       io_uring_clone_buffers - Clones registered buffers between rings

SYNOPSIS        top

#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 intflags);int io_uring_clone_buffers_offset(struct io_uring *dst,struct io_uring *src,unsigned intdst_off,unsigned intsrc_off,unsigned intnr,unsigned intflags);int __io_uring_clone_buffers_offset(struct io_uring *dst,struct io_uring *src,unsigned intdst_off,unsigned intsrc_off,unsigned intnr,unsigned intflags);

DESCRIPTION        top

       Theio_uring_clone_buffers(3) function clones registered buffers       from the ring indicated bysrc to the ring indicated bydst.  Upon       successful completion of this operation,src anddst will have the       same set of registered buffers. This operation is identical to       performing aio_uring_register_buffers(3) operation on thedst       ring, if thesrc ring previously had that same buffer registration       operating done.       Thedst ring must not have any buffers currently registered. If       buffers are currently registered on the destination ring, they       must be unregistered withio_uring_unregister_buffers(3) first.       For__io_uring_clone_buffers(3),the only difference is that it       takes aflags argument. By default, if the destination ring has a       registered file descriptor throughio_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 asio_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 setIORING_REGISTER_SRC_REGISTEREDby 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.       Theio_uring_clone_buffers_offset(3) function also clones buffers       from thesrc ring to thedst ring, however it supports cloning       only a subset of the buffers, whereio_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, andnr indicates how       many buffers to clone at the given offset. If bothdst_off,src_off, andnr are given as0 ,thenio_uring_clone_buffers_offset(3) performs the same action asio_uring_clone_buffers(3).       Whileio_uring_clone_buffers_offset(3) setsIORING_REGISTER_SRC_REGISTEREDby 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.

NOTES        top

       The source and target ring must shared address spaces, and hence       internal kernel accounting.

RETURN VALUE        top

       On successio_uring_clone_buffers(3) andio_uring_clone_buffers_offset(3) return 0.  On failure, they       returns-errno, specifically-EBUSYThe destination ring already has buffers registered, andIORING_REGISTER_DST_REPLACEwasn't set.-ENOMEM              The kernel ran out of memory.-ENXIOThe source ring doesn't have any buffers registered.

SEE ALSO        top

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)

COLOPHON        top

       This page is part of theliburing (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 isnot part of the original manual page), send a mail to       man-pages@man7.orgliburing-2.9                September 12, 2024io_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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