On 6/20/19 11:51 AM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Create a separate manual page for the xfs RESBLKS ioctls so we can
> document how it works.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> man/man2/ioctl_xfs_getresblks.2 | 65 +++++++++++++++++++++++++++++++++++++++
> man/man2/ioctl_xfs_setresblks.2 | 1 +
> man/man3/xfsctl.3 | 14 +++++++-
> 3 files changed, 78 insertions(+), 2 deletions(-)
> create mode 100644 man/man2/ioctl_xfs_getresblks.2
> create mode 100644 man/man2/ioctl_xfs_setresblks.2
>
>
> diff --git a/man/man2/ioctl_xfs_getresblks.2 b/man/man2/ioctl_xfs_getresblks.2
> new file mode 100644
> index 00000000..694b4496
> --- /dev/null
> +++ b/man/man2/ioctl_xfs_getresblks.2
> @@ -0,0 +1,65 @@
> +.\" Copyright (c) 2019, Oracle. All rights reserved.
> +.\"
> +.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
> +.\" SPDX-License-Identifier: GPL-2.0+
> +.\" %%%LICENSE_END
> +.TH IOCTL-XFS-GETRESBLKS 2 2019-06-17 "XFS"
> +.SH NAME
> +ioctl_xfs_getresblks \- query XFS summary counter information
^^^^^^^^^^^^^^^
"query and set XFS free space reservation information"
> +.SH SYNOPSIS
> +.br
> +.B #include <xfs/xfs_fs.h>
> +.PP
> +.BI "int ioctl(int " fd ", XFS_IOC_GET_RESBLKS, struct xfs_fsop_resblks *" arg );
> +.br
> +.BI "int ioctl(int " fd ", XFS_IOC_SET_RESBLKS, struct xfs_fsop_resblks *" arg );
> +.SH DESCRIPTION
I wonder if starting with a "don't use" right here would be wise, something like:
"Note: This is a[n] test/debug ioctl intended only for use by XFS filesystem developers."
> +Query or set the free space reservation information.
> +These blocks are reserved by the filesystem as a final attempt to prevent
> +metadata update failures due to insufficient space.
> +Only the system administrator can call these ioctls, because overriding the
> +defaults is extremely dangerous and should never be tried by anyone.
> +.PP
> +The reservation information is conveyed in a structure of the following form:
> +.PP
> +.in +4n
> +.nf
> +struct xfs_fsop_resblks {
> + __u64 resblks;
> + __u64 resblks_avail;
> +};
> +.fi
> +.in
> +.PP
> +.I resblks
> +is the number of blocks that the filesystem will try to maintain to prevent
> +critical out of space situations.
> +.PP
> +.I resblks_avail
> +is the number of reserved blocks remaining.
> +.SH RETURN VALUE
> +On error, \-1 is returned, and
> +.I errno
> +is set to indicate the error.
> +.PP
> +.SH ERRORS
> +Error codes can be one of, but are not limited to, the following:
> +.TP
> +.B EFSBADCRC
> +Metadata checksum validation failed while performing the query.
> +.TP
> +.B EFSCORRUPTED
> +Metadata corruption was encountered while performing the query.
> +.TP
> +.B EINVAL
> +The specified allocation group number is not valid for this filesystem.
> +.TP
> +.B EIO
> +An I/O error was encountered while performing the query.
> +.TP
> +.B EPERM
> +Caller does not have permission to call this ioctl.
> +.SH CONFORMING TO
> +This API is specific to XFS filesystem on the Linux kernel.
> +.SH SEE ALSO
> +.BR ioctl (2)
> diff --git a/man/man2/ioctl_xfs_setresblks.2 b/man/man2/ioctl_xfs_setresblks.2
> new file mode 100644
> index 00000000..209bc0a8
> --- /dev/null
> +++ b/man/man2/ioctl_xfs_setresblks.2
> @@ -0,0 +1 @@
> +.so man2/ioctl_xfs_getresblks.2
> diff --git a/man/man3/xfsctl.3 b/man/man3/xfsctl.3
> index ee3188ec..89975a3c 100644
> --- a/man/man3/xfsctl.3
> +++ b/man/man3/xfsctl.3
> @@ -396,12 +396,21 @@ See
> .BR ioctl_xfs_fscounts (2)
> for more information.
>
> +.TP
> +.nf
> +.B XFS_IOC_GET_RESBLKS
> +.fi
> +.TP
> +.B XFS_IOC_SET_RESBLKS
> +See
> +.BR ioctl_xfs_getresblks (2)
> +for more information.
> +Save yourself a lot of frustration and avoid these ioctls.
> +
> .PP
> .nf
> .B XFS_IOC_THAW
> .B XFS_IOC_FREEZE
> -.B XFS_IOC_GET_RESBLKS
> -.B XFS_IOC_SET_RESBLKS
> .B XFS_IOC_FSGROWFSDATA
> .B XFS_IOC_FSGROWFSLOG
> .fi
> @@ -419,6 +428,7 @@ as they are not of general use to applications.
> .BR ioctl_xfs_scrub_metadata (2),
> .BR ioctl_xfs_fsinumbers (2),
> .BR ioctl_xfs_fscounts (2),
> +.BR ioctl_xfs_getresblks (2),
> .BR fstatfs (2),
> .BR statfs (2),
> .BR xfs (5),
>
