io_uring_prep_files_update(3) — Linux manual page


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

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

       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

RETURN VALUE         top


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.

              The kernel was unable to allocate memory for the request.

              One of the fields set in the SQE was invalid.

              The kernel was unable to copy in the memory pointed to by

       -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.

              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

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

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