Re: [PATCH -v2] ext4: Handle unwritten extent properly with delayed allocation.

[Mingming Cao <cmm@us.ibm.com>]

> When using fallocate the buffer_heads are marked unwritten
> and unmapped. We need to map them in the writepages after
> a get_block. Otherwise we split the uninit extents,
> but never write the content to disk.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Reviewed-by: Mingming Cao <cmm@us.ibm.com>

Added to patch queue
> ---
>  fs/ext4/inode.c |   12 ++++++++++--
>  1 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index c96cc0b..7a66bba 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1732,6 +1732,13 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
>  				if (buffer_delay(bh)) {
>  					bh->b_blocknr = pblock;
>  					clear_buffer_delay(bh);
> +					bh->b_bdev = inode->i_sb->s_bdev;
> +				} else if (buffer_unwritten(bh)) {
> +					bh->b_blocknr = pblock;
> +					clear_buffer_unwritten(bh);
> +					set_buffer_mapped(bh);
> +					set_buffer_new(bh);
> +					bh->b_bdev = inode->i_sb->s_bdev;
>  				} else if (buffer_mapped(bh))
>  					BUG_ON(bh->b_blocknr != pblock);
> 
> @@ -1805,7 +1812,7 @@ static void mpage_da_map_blocks(struct mpage_da_data *mpd)
>  		 * If blocks are delayed marked, we need to
>  		 * put actual blocknr and drop delayed bit
>  		 */
> -		if (buffer_delay(lbh))
> +		if (buffer_delay(lbh) || buffer_unwritten(lbh))
>  			mpage_put_bnr_to_bhs(mpd, next, &new);
> 
>  		/* go for the remaining blocks */
> @@ -1814,7 +1821,8 @@ static void mpage_da_map_blocks(struct mpage_da_data *mpd)
>  	}
>  }
> 
> -#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | (1 << BH_Delay))
> +#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
> +		(1 << BH_Delay) | (1 << BH_Unwritten))
> 
>  /*
>   * mpage_add_bh_to_extent - try to add one more block to extent of blocks