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Re: [PATCH] xfs: don't ASSERT on corrupt ftype

To: Eric Sandeen <sandeen@xxxxxxxxxxx>
Subject: Re: [PATCH] xfs: don't ASSERT on corrupt ftype
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 9 Sep 2014 08:00:36 +1000
Cc: Eric Sandeen <sandeen@xxxxxxxxxx>, xfs-oss <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <540DB6F3.7090407@xxxxxxxxxxx>
References: <540D011B.2000807@xxxxxxxxxx> <20140908130507.GN30012@dastard> <540DB3FE.6010309@xxxxxxxxxxx> <540DB6F3.7090407@xxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Mon, Sep 08, 2014 at 09:02:27AM -0500, Eric Sandeen wrote:
> On 9/8/14 8:49 AM, Eric Sandeen wrote:
> >On 9/8/14 8:05 AM, Dave Chinner wrote:
> >>On Sun, Sep 07, 2014 at 08:06:35PM -0500, Eric Sandeen wrote:
> >>>xfs_dir3_data_get_ftype() and xfs_dir2_sf_check() get
> >>>the file type off disk, but ASSERT if it's invalid:
> >>>
> >>>    ASSERT(type < XFS_DIR3_FT_MAX);
> >>>
> >>>This might be cut & paste from the "put" functions,
> >>>which should be checking that they've not been passed
> >>>bad values, but we shouldn't ASSERT on bad values
> >>>read from disk.
> >>
> >>No, they weren't cut-n-paste from the put functions. They were
> >>actually designed for a metadata block where bad values would not be
> >>written to disk, and corrupted disk blocks would be detected by CRC
> >>validation failures. So on debug kernels it's quite appropriate to
> >>assert fail on a "should never, ever happen" condition.
> >
> >hohum, ok.
> 
> So then presumably the reason there is no ASSERT in xfs_dir3_sfe_get_ftype
> (vs in xfs_dir3_data_get_ftype) is also purely intentional and
> part of the design, but I'm unable to divine that logic... can you
> help me out?

Because that ASSERT check was put in xfs_dir2_sf_check(). Yeah, I
know, not consistent, but the shortform code is quite different to
the block/leaf/node code....

> I guess the only way forward is to create a 3rd set of ops, and have
> one for dir2, one for dir2-with-ftype, and one for dir3?  Because
> in the op, there's no way to discern between the latter 2, and
> know if we're previously CRC-protected or not...

No, just kill the asset in xfs_dir3_data_get_ftype().

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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