On 6/7/19 2:29 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Create a separate manual page for the INUMBERS ioctl so we can document
> how it works.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> man/man2/ioctl_xfs_fsinumbers.2 | 115 +++++++++++++++++++++++++++++++++++++++
> man/man3/xfsctl.3 | 34 +-----------
> 2 files changed, 119 insertions(+), 30 deletions(-)
> create mode 100644 man/man2/ioctl_xfs_fsinumbers.2
>
>
> diff --git a/man/man2/ioctl_xfs_fsinumbers.2 b/man/man2/ioctl_xfs_fsinumbers.2
> new file mode 100644
> index 00000000..86cdf4d9
> --- /dev/null
> +++ b/man/man2/ioctl_xfs_fsinumbers.2
> @@ -0,0 +1,115 @@
> +.\" Copyright (c) 2019, Oracle. All rights reserved.
> +.\"
> +.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
> +.\" SPDX-License-Identifier: GPL-2.0+
> +.\" %%%LICENSE_END
> +.TH IOCTL-XFS-FSINUMBERS 2 2019-04-16 "XFS"
> +.SH NAME
> +ioctl_xfs_fsinumbers \- extract a list of valid inode numbers from an XFS filesystem
> +.SH SYNOPSIS
> +.br
> +.B #include <xfs/xfs_fs.h>
> +.PP
> +.BI "int ioctl(int " fd ", XFS_IOC_FSINUMBERS, struct xfs_fsop_bulkreq *" arg );
> +.SH DESCRIPTION
> +Query a list of valid inode numbers from an XFS filesystem.
> +It is intended to be called iteratively to obtain the entire set of inodes.
> +These ioctls use
> +.B struct xfs_fsop_bulkreq
> +to set up a bulk transfer with the kernel:
> +.PP
> +.in +4n
> +.nf
> +struct xfs_fsop_bulkreq {
> + __u64 *lastip;
> + __s32 count;
> + void *ubuffer;
> + __s32 *ocount;
> +};
> +.fi
> +.in
> +.PP
> +.I lastip
> +points to a value that will receive the number of the "last inode".
> +This should be set to one less than the number of the first inode for which the
> +caller wants information, or zero to start with the first inode in the
> +filesystem.
> +After the call, this value will be set to the number of the last inode for
> +which information is supplied.
> +This field will not be updated if
> +.I ocount
> +is NULL.
> +.PP
> +.I count
> +is the number of inodes to examine.
again should it have something like "corresponding to the number
of array elements passed in in the ubuffer array?"
> +.PP
> +.I ocount
> +points to a value that will receive the number of records returned.
> +An output value of zero means that there are no more inodes left to enumerate.
> +If this value is NULL, then neither
> +.I ocount
> +nor
> +.I lastip
> +will be updated.
> +.PP
> +.I ubuffer
> +points to a memory buffer where information will be copied.
> +This buffer must be an array of
> +.B struct xfs_inogrp
> +which is described below.
> +The array must have at least
> +.I count
> +elements.
> +.PP
> +.in +4n
> +.nf
> +struct xfs_inogrp {
> + __u64 xi_startino;
> + __s32 xi_alloccount;
> + __u64 xi_allocmask;
> +}
> +.fi
> +.in
> +.PP
> +.I xi_startino
> +is the number of this inode numbers record.
this phrasing confuses me.
xi_startino is the first inode number in this inode... group?
> +Each inode numbers record will correspond roughly to a record in the inode
> +btree, though this is not guaranteed.
I don't think that is useful information.
> +.PP
> +.I xi_alloccount
> +is the number of bits that are set in
> +.IR xi_allocmask .
i.e. the number of inodes in use in this group?
> +.PP
> +.I xi_allocmask
> +is the mask of inodes that are in use for this inode.
inodes that are in use for this inode? wut.
> +The bitmask is 64 bits long, and the least significant bit corresponds to inode
> +.BR xi_startino .
ok so finally we get to what I consider to be the useful thing that ties it
all together ;)
so maybe best to just say that it returns inode usage information for a group of
64 consecutive inode numbers, starting with inode xi_startino, with a bitmask of
in-use inodes in xi_allocmask, with total in-use inodes for this batch/group/set
shown in xi_alloccount?
> +.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 EFAULT
> +The kernel was not able to copy into the userspace buffer.
> +.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
> +One of the arguments was not valid.
> +.TP
> +.B EIO
> +An I/O error was encountered while performing the query.
> +.TP
> +.B ENOMEM
> +There was insufficient memory to perform the query.
> +.SH CONFORMING TO
> +This API is specific to XFS filesystem on the Linux kernel.
> +.SH SEE ALSO
> +.BR ioctl (2)
> diff --git a/man/man3/xfsctl.3 b/man/man3/xfsctl.3
> index cdf0fcfc..148119a9 100644
> --- a/man/man3/xfsctl.3
> +++ b/man/man3/xfsctl.3
> @@ -368,36 +368,9 @@ can be any open file in the XFS filesystem in question.
> .PP
> .TP
> .B XFS_IOC_FSINUMBERS
> -This interface is used to extract a list of valid inode numbers from an
> -XFS filesystem.
> -It is intended to be called iteratively, to obtain the entire set of inodes.
> -The information is passed in and out via a structure of type
> -.B xfs_fsop_bulkreq_t
> -pointed to by the final argument.
> -.B lastip
> -is a pointer to a variable containing the last inode number returned,
> -initially it should be zero.
> -.B icount
> -is the size of the array of structures specified by
> -.BR ubuffer .
> -.B ubuffer
> -is the address of an array of structures, of type
> -.BR xfs_inogrp_t .
> -This structure has the following elements:
> -.B xi_startino
> -(starting inode number),
> -.B xi_alloccount
> -(count of bits set in xi_allocmask), and
> -.B xi_allocmask
> -(mask of allocated inodes in this group).
> -The bitmask is 64 bits long, and the least significant bit corresponds to inode
> -.B xi_startino.
> -Each bit is set if the corresponding inode is in use.
> -.B ocount
> -is a pointer to a count of returned values, filled in by the call.
> -An output
> -.B ocount
> -value of zero means that the inode table has been exhausted.
> +See
> +.BR ioctl_xfs_fsinumbers (2)
> +for more information.
>
> .TP
> .B XFS_IOC_FSGEOMETRY
> @@ -442,6 +415,7 @@ as they are not of general use to applications.
> .BR ioctl_xfs_fsgetxattr (2),
> .BR ioctl_xfs_fsop_geometry (2),
> .BR ioctl_xfs_fsbulkstat (2),
> +.BR ioctl_xfs_fsinumbers (2),
> .BR fstatfs (2),
> .BR statfs (2),
> .BR xfs (5),
>
