Re: [PATCH v2] man/man2: introduce man page for file_getattr/file_setattr syscalls

[Alejandro Colomar <alx@kernel.org>]

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Hi Darrick,

> Date: 2026-09-10 09:12:04-0700
> From: "Darrick J. Wong" <djwong@kernel.org>
>
> On Thu, Sep 10, 2026 at 03:20:25PM +0200, Alejandro Colomar wrote:
> > 
> > > Date: 2026-09-10 12:41:18+0200
> > > From: Andrey Albershteyn <aalbersh@kernel.org>
[...]
> > > +.SH DESCRIPTION
> > > +The
> > > +.BR file_getattr ()
> > > +system call retrieves filesystem file attributes
> > > +from the file specified by
> > > +.IR pathname .
> > > +.P
> > > +This system call provides functionality similar to the
> > > +.B FS_IOC_FSGETXATTR
> > > +.BR ioctl (2)
> > > +operation,
> > 
> > Should we document FS_IOC_FSGETXATTR in a new FS_IOC_FSGETXATTR(2const)
> > manual page?
> 
> https://www.man7.org/linux/man-pages/man2/ioctl_xfs_fssetxattr.2.html

Thanks!  I didn't know that page.

I see the page uses the constants as XFS_ instead of FS_?  I think the
page should have some mention about it, especially since it says non-xfs
filesystems also implement this.  Is it the same as (or related to)
what's mentioned in quotactl(2)?

	NOTES
	   Alternative XFS header
	     Instead of <xfs/xqm.h> one  can  use  <linux/dqblk_xfs.h>,
	     taking into account that there are several naming discrep‐
	     ancies:

	     •  Quota       enabling       flags       (of       format
		XFS_QUOTA_[UGP]DQ_{ACCT,ENFD}) are  defined  without  a
		leading "X", as FS_QUOTA_[UGP]DQ_{ACCT,ENFD}.

	     •  The  same is true for XFS_{USER,GROUP,PROJ}_QUOTA quota
		type     flags,     which      are      defined      as
		FS_{USER,GROUP,PROJ}_QUOTA.

	     •  The  dqblk_xfs.h  header  file  defines its own XQM_US‐
		RQUOTA, XQM_GRPQUOTA, and  XQM_PRJQUOTA  constants  for
		the  available  quota  types,  but their values are the
		same as for constants without the XQM_ prefix.

I think we should probably have a xfs-xqm(2head) manual page documenting
these conventions, I think.

Also, given it doesn't seem exclusive of xfs, should we move the manual
page to the Linux man-pages (from xfsprogs)?

> > > +but with the advantage that the file does not need to be opened.
> > > +By using a pathname,
> > > +.BR file_getattr ()
> > > +can retrieve filesystem file attributes
> > > +from all file types,
> > > +including special files such as FIFOs, sockets, block devices, character
> > > +devices, and symlinks, where opening the targeted inode may not be possible.
> > 
> > This seems to be a limitation of FS_IOC_FSGETXATTR(2const), and would be
> > more appropriately documented in that page (if we add it).  There, I'd
> > document it in CAVEATS.  Then, file_getattr(2) wouldn't need to mention
> > this at all, because it's not an issue here.
> 
> Agreed, that belongs in ioctl_xfs_fssetxattr.2, not here.

Thanks!

> 
> --D

Have a lovely day!
Alex

-- 
<https://www.alejandro-colomar.es>

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