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From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: xfs <linux-xfs@vger.kernel.org>
Subject: Re: [PATCH] xfs: don't expose misaligned extszinherit hints to userspace
Date: Fri, 9 Jul 2021 07:25:09 +0100	[thread overview]
Message-ID: <YOfrxV9p1Bhrs1jD@infradead.org> (raw)
In-Reply-To: <20210709041209.GO11588@locust>

On Thu, Jul 08, 2021 at 09:12:09PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Commit 603f000b15f2 changed xfs_ioctl_setattr_check_extsize to reject an
> attempt to set an EXTSZINHERIT extent size hint on a directory with
> RTINHERIT set if the hint isn't a multiple of the realtime extent size.
> However, I have recently discovered that it is possible to change the
> realtime extent size when adding a rt device to a filesystem, which
> means that the existence of directories with misaligned inherited hints
> is not an accident.
> 
> As a result, it's possible that someone could have set a valid hint and
> added an rt volume with a different rt extent size, which invalidates
> the ondisk hints.  After such a sequence, FSGETXATTR will report a
> misaligned hint, which FSSETXATTR will trip over, causing confusion if
> the user was doing the usual GET/SET sequence to change some other
> attribute.  Change xfs_fill_fsxattr to omit the hint if it isn't aligned
> properly.

Looks sensible, but maybe we need a pr_info_ratelimited to inform
the user of this case?

  parent reply	other threads:[~2021-07-09  6:25 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-09  4:12 [PATCH] xfs: don't expose misaligned extszinherit hints to userspace Darrick J. Wong
2021-07-09  4:14 ` [RFC PATCH] xfs: test adding realtime sections to filesystem Darrick J. Wong
2021-07-09  6:25 ` Christoph Hellwig [this message]
2021-07-10  3:58   ` [PATCH] xfs: don't expose misaligned extszinherit hints to userspace Darrick J. Wong
2021-07-12 11:22     ` Christoph Hellwig

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