io_uring_prep_files_update(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | NOTES | SEE ALSO | COLOPHON

io_uring_pr...iles_update(3) liburing Manualio_uring_pr...iles_update(3)

NAME         top

       io_uring_prep_files_update - prepare a registered file update
       request

SYNOPSIS         top

       #include <liburing.h>

       void io_uring_prep_files_update(struct io_uring_sqe *sqe,
                                       int *fds,
                                       unsigned nr_fds,
                                       int offset);

DESCRIPTION         top

       The io_uring_prep_files_update(3) function prepares a request for
       updating a number of previously registered file descriptors. The
       submission queue entry sqe is setup to use the file descriptor
       array pointed to by fds and of nr_fds in length to update that
       amount of previously registered files starting at offset offset.

       Once a previously registered file is updated with a new one, the
       existing entry is updated and then removed from the table. This
       operation is equivalent to first unregistering that entry and
       then inserting a new one, just bundled into one combined
       operation.

       If offset is specified as IORING_FILE_INDEX_ALLOC, io_uring will
       allocate free direct descriptors instead of having the
       application to pass, and store allocated direct descriptors into
       fds array, cqe->res will return the number of direct descriptors
       allocated.

RETURN VALUE         top

       None

ERRORS         top

       These are the errors that are reported in the CQE res field. On
       success, res will contain the number of successfully updated file
       descriptors. On error, the following errors can occur.

       -ENOMEM
              The kernel was unable to allocate memory for the request.

       -EINVAL
              One of the fields set in the SQE was invalid.

       -EFAULT
              The kernel was unable to copy in the memory pointed to by
              fds.

       -EBADF On of the descriptors located in fds didn't refer to a
              valid file descriptor, or one of the file descriptors in
              the array referred to an io_uring instance.

       -EOVERFLOW
              The product of offset and nr_fds exceed the valid amount
              or overflowed.

NOTES         top

       As with any request that passes in data in a struct, that data
       must remain valid until the request has been successfully
       submitted. It need not remain valid until completion. Once a
       request has been submitted, the in-kernel state is stable. Very
       early kernels (5.4 and earlier) required state to be stable until
       the completion occurred. Applications can test for this behavior
       by inspecting the IORING_FEAT_SUBMIT_STABLE flag passed back from
       io_uring_queue_init_params(3).

SEE ALSO         top

       io_uring_get_sqe(3), io_uring_submit(3), io_uring_register(2)

COLOPHON         top

       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 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
       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-2.2                 March 13, 2022 io_uring_pr...iles_update(3)

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