io_uring_prep_read_fixed(3) — Linux manual page


io_uring_prep_read(3)        liburing Manual       io_uring_prep_read(3)

NAME         top

       io_uring_prep_read_fixed - prepare I/O read request with
       registered buffer

SYNOPSIS         top

       #include <liburing.h>

       void io_uring_prep_read_fixed(struct io_uring_sqe *sqe,
                               int fd,
                               void *buf,
                               unsigned nbytes,
                               __u64 offset,
                               int buf_index);

DESCRIPTION         top

       The io_uring_prep_read_fixed(3) prepares an IO read request with
       a previously registered IO buffer. The submission queue entry sqe
       is setup to use the file descriptor fd to start reading nbytes
       into the buffer buf at the specified offset, and with the buffer
       matching the registered index of buf_index.

       This works just like io_uring_prep_read(3) except it requires the
       use of buffers that have been registered with
       io_uring_register_buffers(3).  The buf and nbytes arguments must
       fall within a region specified by buf_index in the previously
       registered buffer. The buffer need not be aligned with the start
       of the registered buffer.

       After the read has been prepared it can be submitted with one of
       the submit functions.

RETURN VALUE         top


ERRORS         top

       The CQE res field will contain the result of the operation. See
       the related man page for details on possible values. Note that
       where synchronous system calls will return -1 on failure and set
       errno to the actual error value, io_uring never uses errno.
       Instead it returns the negated errno directly in the CQE res

SEE ALSO         top

       io_uring_prep_read(3), io_uring_register_buffers(3)

COLOPHON         top

       This page is part of the liburing (A library for io_uring)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for
       this manual page, send it to  This page
       was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-19.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
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       (which is not part of the original manual page), send a mail to

liburing-2.1                February 13, 2022      io_uring_prep_read(3)

Pages that refer to this page: io_uring_prep_read_fixed(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)