Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx> --- man/io_uring_prep_cmd_discard.3 | 60 +++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 man/io_uring_prep_cmd_discard.3 diff --git a/man/io_uring_prep_cmd_discard.3 b/man/io_uring_prep_cmd_discard.3 new file mode 100644 index 0000000..75e25bb --- /dev/null +++ b/man/io_uring_prep_cmd_discard.3 @@ -0,0 +1,60 @@ +.\" Copyright (C) 2024 Pavel Begunkov <asml.silence@xxxxxxxxx> +.\" +.\" SPDX-License-Identifier: LGPL-2.0-or-later +.\" +.TH io_uring_prep_cmd_discard 3 "Oct 13, 2024" "liburing-2.8" "liburing Manual" +.SH NAME +io_uring_prep_cmd_discard \- prepare a discard command +.SH SYNOPSIS +.nf +.B #include <liburing.h> +.PP +.BI "void io_uring_prep_cmd_discard(struct io_uring_sqe *" sqe "," +.BI " int " fd "," +.BI " uint64_t " offset "," +.BI " uint64_t " nbytes ");" +.fi +.SH DESCRIPTION +The +.BR io_uring_prep_cmd_discard (3) +function prepares a discard command request. The submission queue entry +.I sqe +is setup to use the file descriptor +.IR fd +to start discarding +.I nbytes +at the specified +.IR offset . + +The command is an asynchronous equivalent of +.B 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, and it's the user's responsibility to account for that. +Furthermore, we only do best effort to invalidate page caches, the user has +to make sure there are no other inflight requests are modifying or reading +the range(s), otherwise it might result in stale page cache and data +inconsistencies. + +Available since 6.12. + +.SH RETURN VALUE +None +.SH ERRORS +The CQE +.I 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 +.B -1 +on failure and set +.I errno +to the actual error value, io_uring never uses +.IR errno . +Instead it returns the negated +.I errno +directly in the CQE +.I res +field. +.SH SEE ALSO +.BR io_uring_get_sqe (3), +.BR io_uring_submit (3), -- 2.46.0
