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From: David Howells <>
To: Christoph Hellwig <>
Subject: Re: [PATCH 2/2] afs: Add metadata xattrs
Date: Thu, 06 Jul 2017 17:14:11 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Christoph Hellwig <> wrote:

> NAK.  Don't overload xattrs with magic behavior just to avoid the need
> to do proper syscalls or ioctls.

How?  This has to work on non-files, files you can't open and mountpoints.
You can't do an ioctl() on a file opened O_PATH:

	if (unlikely(f->f_flags & O_PATH)) {
		f->f_mode = FMODE_PATH;
		f->f_op = &empty_fops;
		return 0;

and you can't specify AT_NO_AUTOMOUNT or AT_NO_FOLLOW to openat(), so ioctl()
is of no use here.

Do you advocate introducing a pioctl() call?  Linus was dead-set against that
as I recall.

I could invent a bunch of AFS-specific syscalls, but I'd rather not do that or
I suppose bring my fsinfo() patches up to scratch - but you didn't like those

Note that using xattrs for fs info is not without precedent in Linux - cifs,
for example.


  parent reply	other threads:[~2017-07-06 16:14 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
     [not found] ` <>
2017-07-06 15:23   ` Christoph Hellwig
2017-07-06 16:14   ` David Howells [this message]
2017-07-06 18:27     ` Andreas Dilger
2017-07-08 19:44       ` Linus Torvalds
2017-07-09  1:01         ` Theodore Ts'o
     [not found]           ` <>
2017-07-09  2:37             ` Jeffrey Altman

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