From: Kalpak Shah <kalpak@clusterfs.com>
Subject: Re: [RFC][PATCH] Multiple mount protection
Date: Fri, 01 Jun 2007 02:39:32 +0530
Message-ID: <1180645773.3922.8.camel@garfield>
References: <1179777153.3910.13.camel@garfield>
	 <20070525143957.GA12669@thunk.org> <1180128981.3916.13.camel@garfield>
	 <1180558715.3949.3.camel@garfield>  <20070531161627.GE19088@thunk.org>
Mime-Version: 1.0
Content-Type: text/plain
Content-Transfer-Encoding: 7bit
Cc: linux-ext4 <linux-ext4@vger.kernel.org>,
	Andreas Dilger <adilger@clusterfs.com>
To: Theodore Tso <tytso@mit.edu>
In-Reply-To: <20070531161627.GE19088@thunk.org>
Sender: linux-ext4-owner@vger.kernel.org

On Thu, 2007-05-31 at 12:16 -0400, Theodore Tso wrote:
> On Thu, May 31, 2007 at 02:28:33AM +0530, Kalpak Shah wrote:
> > 
> > So can I assume that the INCOMPAT_MMP flag and the s_mmp_interval and
> > s_mmp_block superblock fields will be reserved regardless of whether the
> > patches go into ext4? I had attached the patches in the last mail so you
> > can share your views on them.
> 
> Yes, i've reserved the code point and superblock fields.

Thanks.

>   I'm not going to add INCOMPAT_MMP flag to the supported file until I get and
> integrate the patch ext2fs_open() that actually tests for the flag,
> though, since that would be a bit silly.
> 
> I assume the patch will add a flag to ext2fs_open which skips the MMP
> checking.

Yes I have added a EXT2_FLAG_SKIP_MMP flag to ext2fs_open() to bypass
MMP which will be set if tunefs is used with -f option. Also MMP check
will not be run if the filesystem is being opened readonly.

Thanks,
Kalpak.

>   After all, tune2fs is allowed to make changes to the
> superblock while the filesystem is mounted.  So it needs to be able to
> open the filesystem read/only even if it is mounted.
> 
> Regards,
> 
> 						- Ted