[V2] resize2fs: clear uninit BG if allocating from new group

If resize2fs_get_alloc_block() allocates from a BLOCK_UNINIT
group, nothing clears the UNINIT flag, so it is skipped when we
go to write out modified bitmaps.  This leads to post-resize2fs
e2fsck errors; used blocks in UNINIT groups, not marked in the
block bitmap.  This was seen on r_ext4_small_bg.

This patch uses clear_block_uninit() to clear the flag,
and my problem goes away.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

V2: don't cut and paste, sorry! :)

Thanks,
-Eric


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On Thu, Jan 14, 2016 at 12:46:03PM -0600, Eric Sandeen wrote:
> If resize2fs_get_alloc_block() allocates from a BLOCK_UNINIT
> group, nothing clears the UNINIT flag, so it is skipped when we
> go to write out modified bitmaps.  This leads to post-resize2fs
> e2fsck errors; used blocks in UNINIT groups, not marked in the
> block bitmap.  This was seen on r_ext4_small_bg.
> 
> This patch uses clear_block_uninit() to clear the flag,
> and my problem goes away.
> 
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
> 
> V2: don't cut and paste, sorry! :)
> 
> Thanks,
> -Eric
> 
> diff --git a/lib/ext2fs/alloc.c b/lib/ext2fs/alloc.c
> index 86e7f99..9a575fd 100644
> --- a/lib/ext2fs/alloc.c
> +++ b/lib/ext2fs/alloc.c
> @@ -39,7 +39,7 @@
>  /*
>   * Clear the uninit block bitmap flag if necessary
>   */
> -static void clear_block_uninit(ext2_filsys fs, dgrp_t group)
> +void clear_block_uninit(ext2_filsys fs, dgrp_t group)
>  {
>  	if (!ext2fs_has_group_desc_csum(fs) ||
>  	    !(ext2fs_bg_flags_test(fs, group, EXT2_BG_BLOCK_UNINIT)))
> diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
> index 86d860f..0dca002 100644
> --- a/lib/ext2fs/ext2fs.h
> +++ b/lib/ext2fs/ext2fs.h
> @@ -647,6 +647,7 @@ static inline int ext2fs_needs_large_file_feature(unsigned long long file_size)
>  }
>  
>  /* alloc.c */
> +extern void clear_block_uninit(ext2_filsys fs, dgrp_t group);

If you're going to expose this as a new API call then this needs to be
ext2fs_clear_block_uninit().

(Do we want a flags arg just in case we ever need one?)

--D

>  extern errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir, int mode,
>  				  ext2fs_inode_bitmap map, ext2_ino_t *ret);
>  extern errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,
> diff --git a/resize/resize2fs.c b/resize/resize2fs.c
> index 07c6a0c..ffe9473 100644
> --- a/resize/resize2fs.c
> +++ b/resize/resize2fs.c
> @@ -1620,6 +1620,7 @@ static errcode_t resize2fs_get_alloc_block(ext2_filsys fs,
>  {
>  	ext2_resize_t rfs = (ext2_resize_t) fs->priv_data;
>  	blk64_t blk;
> +	int group;
>  
>  	blk = get_new_block(rfs);
>  	if (!blk)
> @@ -1632,6 +1633,12 @@ static errcode_t resize2fs_get_alloc_block(ext2_filsys fs,
>  
>  	ext2fs_mark_block_bitmap2(rfs->old_fs->block_map, blk);
>  	ext2fs_mark_block_bitmap2(rfs->new_fs->block_map, blk);
> +
> +	group = ext2fs_group_of_blk2(rfs->old_fs, blk);
> +	clear_block_uninit(rfs->old_fs, group);
> +	group = ext2fs_group_of_blk2(rfs->new_fs, blk);
> +	clear_block_uninit(rfs->new_fs, group);
> +
>  	*ret = (blk64_t) blk;
>  	return 0;
>  }
> 
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On 1/14/16 12:50 PM, Darrick J. Wong wrote:
> On Thu, Jan 14, 2016 at 12:46:03PM -0600, Eric Sandeen wrote:
...

>> diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
>> index 86d860f..0dca002 100644
>> --- a/lib/ext2fs/ext2fs.h
>> +++ b/lib/ext2fs/ext2fs.h
>> @@ -647,6 +647,7 @@ static inline int ext2fs_needs_large_file_feature(unsigned long long file_size)
>>  }
>>  
>>  /* alloc.c */
>> +extern void clear_block_uninit(ext2_filsys fs, dgrp_t group);
> 
> If you're going to expose this as a new API call then this needs to be
> ext2fs_clear_block_uninit().

Hm, yes.  I tried to work around it but don't see a nice way.

> (Do we want a flags arg just in case we ever need one?)

No.  ;)

(EXT2_CLEAR_GROUP_UNINIT_HALFWAY?  I can't really think of any reasonable
variation on "clear this group's uninit status")

-Eric
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