[Ocfs2-devel] [PATCH] ocfs2: Limit default local alloc size within bitmap range.

[tristan]

Tested-by: Tristan Ye <tristan.ye at oracle.com>

Tao Ma wrote:
> In commit 6b82021b9e91cd689fdffadbcdb9a42597bbe764, we increase
> our local alloc size and calculate how much megabytes we can
> get according to group size and volume size.
> But we also need to check the maximum bits a local alloc block
> bitmap can have. With a bs=512, cs=32K, local volume with 160G,
> it calculate 96MB while the maximum local alloc size is only
> 76M. So the bitmap will overflow and corrupt the system truncate
> log file. See bug
> http://oss.oracle.com/bugzilla/show_bug.cgi?id=1262
>
> Cc: Mark Fasheh <mfasheh at suse.com>
> Signed-off-by: Tao Ma <tao.ma at oracle.com>
> ---
>  fs/ocfs2/localalloc.c |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/fs/ocfs2/localalloc.c b/fs/ocfs2/localalloc.c
> index 3d74196..ec6adbf 100644
> --- a/fs/ocfs2/localalloc.c
> +++ b/fs/ocfs2/localalloc.c
> @@ -118,6 +118,7 @@ unsigned int ocfs2_la_default_mb(struct ocfs2_super *osb)
>  {
>  	unsigned int la_mb;
>  	unsigned int gd_mb;
> +	unsigned int la_max_mb;
>  	unsigned int megs_per_slot;
>  	struct super_block *sb = osb->sb;
>  
> @@ -182,6 +183,12 @@ unsigned int ocfs2_la_default_mb(struct ocfs2_super *osb)
>  	if (megs_per_slot < la_mb)
>  		la_mb = megs_per_slot;
>  
> +	/* We can't store more bits than we can in a block. */
> +	la_max_mb = ocfs2_clusters_to_megabytes(osb->sb,
> +						ocfs2_local_alloc_size(sb) * 8);
> +	if (la_mb > la_max_mb)
> +		la_mb = la_max_mb;
> +
>  	return la_mb;
>  }
>