linux-ext4 - Re: [PATCH 1/2] ext4: Don't count free clusters from a corrupt block group

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Date:	Fri, 27 Sep 2013 11:03:17 -0700
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	tytso@....edu, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 1/2] ext4: Don't count free clusters from a corrupt block
 group

On Fri, Sep 27, 2013 at 01:37:24PM +0800, Zheng Liu wrote:
> On Thu, Sep 26, 2013 at 05:03:28PM -0700, Darrick J. Wong wrote:
> > A bg that's been flagged "corrupt" by definition has no free blocks, so that
> > the allocator won't be tempted to use the damaged bg.  Therefore, we shouldn't
> > count the clusters in the damaged group when calculating free counts.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
> > ---
> >  fs/ext4/balloc.c |    7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > 
> > diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> > index dc5d572..4390f9f 100644
> > --- a/fs/ext4/balloc.c
> > +++ b/fs/ext4/balloc.c
> > @@ -640,6 +640,7 @@ ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
> >  	struct ext4_group_desc *gdp;
> >  	ext4_group_t i;
> >  	ext4_group_t ngroups = ext4_get_groups_count(sb);
> > +	struct ext4_group_info *grp;
> >  #ifdef EXT4FS_DEBUG
> 
> It seems that you forgot to add these code in this macro definition.

Oops, you're right, I did neglect the #if EXT4FS_DEBUG case.  Thank you for
catching that!

--D
> 
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index dc5d572..3ba2079 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -655,7 +655,11 @@ ext4_fsblk_t ext4_count_free_clusters(struct
> super_block *sb)
>                 gdp = ext4_get_group_desc(sb, i, NULL);
>                 if (!gdp)
>                         continue;
> -               desc_count += ext4_free_group_clusters(sb, gdp);
> +               grp = NULL;
> +               if (EXT4_SB(sb)->s_group_info)
> +                       grp = ext4_get_group_info(sb, i);
> +               if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
> +                       desc_count += ext4_free_group_clusters(sb, gdp);
>                 brelse(bitmap_bh);
>                 bitmap_bh = ext4_read_block_bitmap(sb, i);
>                 if (bitmap_bh == NULL)
> 
>                                                 - Zheng
> 
> >  	struct ext4_super_block *es;
> >  	ext4_fsblk_t bitmap_count;
> > @@ -679,7 +680,11 @@ ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
> >  		gdp = ext4_get_group_desc(sb, i, NULL);
> >  		if (!gdp)
> >  			continue;
> > -		desc_count += ext4_free_group_clusters(sb, gdp);
> > +		grp = NULL;
> > +		if (EXT4_SB(sb)->s_group_info)
> > +			grp = ext4_get_group_info(sb, i);
> > +		if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
> > +			desc_count += ext4_free_group_clusters(sb, gdp);
> >  	}
> >  
> >  	return desc_count;
> > 
> > --
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