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Subject: Re: [PATCH] erofs: fix 1 lcluster-sized pcluster for big pcluster
To:     Gao Xiang <xiang@kernel.org>, <linux-erofs@lists.ozlabs.org>
CC:     LKML <linux-kernel@vger.kernel.org>
References: <20210510064715.29123-1-xiang@kernel.org>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <06a646a0-8436-2fd7-4c1b-1d5ea86c600e@huawei.com>
Date:   Thu, 13 May 2021 14:54:26 +0800
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On 2021/5/10 14:47, Gao Xiang wrote:
> If the 1st NONHEAD lcluster of a pcluster isn't CBLKCNT lcluster type
> rather than a HEAD or PLAIN type instead, which means its pclustersize
> _must_ be 1 lcluster (since its uncompressed size < 2 lclusters),
> as illustrated below:
> 
>         HEAD     HEAD / PLAIN    lcluster type
>     ____________ ____________
>    |_:__________|_________:__|   file data (uncompressed)
>     .                .
>    .____________.
>    |____________|                pcluster data (compressed)
> 
> Such on-disk case was explained before [1] but missed to be handled
> properly in the runtime implementation.
> 
> It can be observed if manually generating 1 lcluster-sized pcluster
> with 2 lclusters (thus CBLKCNT doesn't exist.) Let's fix it now.
> 
> [1] https://lore.kernel.org/r/20210407043927.10623-1-xiang@kernel.org
> Fixes: cec6e93beadf ("erofs: support parsing big pcluster compress indexes")
> Signed-off-by: Gao Xiang <xiang@kernel.org>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,