Re: [PATCH] ext4: recalculate s_blockfile_groups during resize2fs

[Lachlan McIlroy <lmcilroy@redhat.com>]

----- Original Message -----
> s_blockfile_groups is used to limit allocations for non-extent
> files to block groups with block numbers less than 2^32.
> However, it's not updated when the filesystem is resized online,
> so the new groups are unavailable to non-extent files until a remount.
> 
> Fix this by updating the value in ext4_update_super() at
> resize time.
> 
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
> 
> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
> index c169477..1357260 100644
> --- a/fs/ext4/resize.c
> +++ b/fs/ext4/resize.c
> @@ -1341,6 +1341,8 @@ static void ext4_update_super(struct super_block *sb,
>  
>  	/* Update the global fs size fields */
>  	sbi->s_groups_count += flex_gd->count;
> +	sbi->s_blockfile_groups = min_t(ext4_group_t, sbi->s_groups_count,
> +			(EXT4_MAX_BLOCK_FILE_PHYS / EXT4_BLOCKS_PER_GROUP(sb)));
>  
>  	/* Update the reserved block counts only once the new group is
>  	 * active. */
> 
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Good catch Eric - this would have prevented the bug in
ext4_mb_regular_allocator() too.  Looks good to me.