linux-kernel - Re: [PATCH 4/6] Ext4: fail if we try to use hole punch

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Message-ID: <4CE2B7C7.4080406@draigBrady.com>
Date:	Tue, 16 Nov 2010 16:56:39 +0000
From:	Pádraig Brady <P@...igBrady.com>
To:	Josef Bacik <josef@...hat.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] Ext4: fail if we try to use hole punch

On 16/11/10 16:33, Josef Bacik wrote:
> On Tue, Nov 16, 2010 at 04:20:43PM +0000, Pádraig Brady wrote:
>>
>> So for older versions of ext4 or other filesystems, how do we know
>> that fallocate(...,FALLOC_FL_PUNCH_HOLE) is not supported.
>> I.E. how do we detect at runtime that the call succeeded
>> and didn't just do a normal fallocate()?
>>
> 
> Older kernels won't accept FALLOC_FL_PUNCH_HOLE, so you'll get an error.
> Thanks,

Oops right.
Older kernels filter FALLOC_FL_PUNCH_HOLE at a higher level in fs/open.c
Whereas newer kernels will do it per file system.

thanks,
Pádraig.
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