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

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:

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Date: 2026-09-10 12:41:18+0200
From: Andrey Albershteyn <aalbersh@kernel.org>

[...]

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+.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)?

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+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>