On Mon, Jun 17, 2019 at 11:34:00AM -0500, Eric Sandeen wrote:
>
>
> 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?"
Fixed.
> > +.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?
Yes, will chnage it to that.
> > +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.
Ok.
> > +.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?
Yes. I'll add a second sentence stating this.
> > +.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.
Yeah, is dumb.
"is a bitmask of inodes that are allocated in this inode group."
> > +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?
Yep. I'll try to clarify this more in the manpage.
--D
>
> > +.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),
> >
