linux-ext4 - Re: [RFC PATCH] ext2: drop cached block when detecting corruption

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Date:   Fri, 5 Jun 2020 17:26:10 +0200
From:   Jan Kara <jack@...e.cz>
To:     cgxu <cgxu519@...ernel.net>
Cc:     jack@...e.com, linux-ext4@...r.kernel.org
Subject: Re: [RFC PATCH] ext2: drop cached block when detecting corruption

On Thu 04-06-20 14:26:49, cgxu wrote:
> On 6/3/20 5:44 PM, Chengguang Xu wrote:
> > Currently ext2 uses mdcache for deduplication of extended
> > attribution blocks. However, there is lack of handling for
> > corrupted blocks, so newly created EAs may still links to
> > corrupted blocks. This patch tries to drop cached block
> > when detecting corruption to mitigate the effect.
> 
> ext2_xattr_cmp() will carefully check every entry in the block,
> so there is no chance to link to corrupted block, maybe we can
> improve the speed of cache related operations by dropping
> corrupted blocks.

Thanks for the back but as you write, I don't see the point of your patch
because corrupted blocks shouldn't get to mbcache in the first place (and
we check block consistency only when loading block from disk, not from
mbcache). And performance in case of corrupted xattr block doesn't really
matter much so I don't want to complicate the code for that.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR