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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | SEE ALSO | COLOPHON |
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io_uring_prep_cmd_discard(3) liburing Manual io_uring_prep_cmd_discard(3)
io_uring_prep_cmd_discard - prepare a discard command
#include <liburing.h>
void io_uring_prep_cmd_discard(struct io_uring_sqe *sqe,
int fd,
uint64_t offset,
uint64_t nbytes);
The io_uring_prep_cmd_discard(3) function prepares a discard
command request. The submission queue entry sqe is setup to use
the file descriptor fd to start discarding nbytes at the specified
offset.
The command is an asynchronous equivalent of
BLOCK_URING_CMD_DISCARD ioctl with a few differences. It allows
multiple parallel discards, and it does not exclude concurrent
writes and reads. As a result, it may lead to races for the data
on the disk, if the application has IO inflight for the same
ranges that the discard operates on. It's the user's
responsibility to account for that. Furthermore, only best
efforts are done to invalidate page caches. The user has to make
sure that no other inflight requests are modifying or reading the
range(s). If that is the case, it might result in stale page cache
and data inconsistencies.
Available since 6.12.
None
The CQE res field will contain the result of the operation. On
success, this field will be set to 0 . On error, a negative error
value is returned. 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 field.
io_uring_get_sqe(3), io_uring_submit(3),
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 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 is not part of the original manual page), send a mail to
man-pages@man7.org
liburing-2.8 Oct 13, 2024 io_uring_prep_cmd_discard(3)
Pages that refer to this page: io_uring_prep_cmd_discard(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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