93 lines
2.7 KiB
Groff
93 lines
2.7 KiB
Groff
.\" Copyright (C) 2022 Jens Axboe <axboe@kernel.dk>
|
|
.\"
|
|
.\" SPDX-License-Identifier: LGPL-2.0-or-later
|
|
.\"
|
|
.TH io_uring_prep_files_update 3 "March 13, 2022" "liburing-2.2" "liburing Manual"
|
|
.SH NAME
|
|
io_uring_prep_files_update \- prepare a registered file update request
|
|
.SH SYNOPSIS
|
|
.nf
|
|
.B #include <liburing.h>
|
|
.PP
|
|
.BI "void io_uring_prep_files_update(struct io_uring_sqe *" sqe ","
|
|
.BI " int *" fds ","
|
|
.BI " unsigned " nr_fds ","
|
|
.BI " int " offset ");"
|
|
.fi
|
|
.SH DESCRIPTION
|
|
.PP
|
|
The
|
|
.BR io_uring_prep_files_update (3)
|
|
function prepares a request for updating a number of previously registered file
|
|
descriptors. The submission queue entry
|
|
.I sqe
|
|
is setup to use the file descriptor array pointed to by
|
|
.I fds
|
|
and of
|
|
.I nr_fds
|
|
in length to update that amount of previously registered files starting at
|
|
offset
|
|
.IR 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
|
|
.I 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
|
|
.I fds
|
|
array,
|
|
.I cqe->res
|
|
will return the number of direct descriptors allocated.
|
|
|
|
.SH RETURN VALUE
|
|
None
|
|
.SH ERRORS
|
|
These are the errors that are reported in the CQE
|
|
.I res
|
|
field. On success,
|
|
.I res
|
|
will contain the number of successfully updated file descriptors. On error,
|
|
the following errors can occur.
|
|
.TP
|
|
.B -ENOMEM
|
|
The kernel was unable to allocate memory for the request.
|
|
.TP
|
|
.B -EINVAL
|
|
One of the fields set in the SQE was invalid.
|
|
.TP
|
|
.B -EFAULT
|
|
The kernel was unable to copy in the memory pointed to by
|
|
.IR fds .
|
|
.TP
|
|
.B -EBADF
|
|
On of the descriptors located in
|
|
.I fds
|
|
didn't refer to a valid file descriptor, or one of the file descriptors in
|
|
the array referred to an io_uring instance.
|
|
.TP
|
|
.B -EOVERFLOW
|
|
The product of
|
|
.I offset
|
|
and
|
|
.I nr_fds
|
|
exceed the valid amount or overflowed.
|
|
.SH NOTES
|
|
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
|
|
.B IORING_FEAT_SUBMIT_STABLE
|
|
flag passed back from
|
|
.BR io_uring_queue_init_params (3).
|
|
.SH SEE ALSO
|
|
.BR io_uring_get_sqe (3),
|
|
.BR io_uring_submit (3),
|
|
.BR io_uring_register (2)
|