[Ocfs2-devel] [PATCH] ocfs2: Fill-in the unused portion of the block with zeros by dio_zero_block()

[Zhen Ren]

Hi Yiwen,

I try to reproduce this case, but it didn't act like you describe.
What I did:
===
laptop:/mnt/shared # mount | grep ocfs2
ocfs2_dlmfs on /dlm type ocfs2_dlmfs (rw,relatime)
/dev/sda3 on /mnt/shared type ocfs2 (rw,relatime,_netdev,heartbeat=local,nointr,data=ordered,errors=remount-ro,atime_quantum=60,coherency=full,user_xattr,acl)
laptop:/mnt/shared # dd if=/dev/zero of=/mnt/shared/hello bs=512 count=1 oflag=direct
1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.000684382 s, 748 kB/s
laptop:/mnt/shared # truncate hello -s 2097152
laptop:/mnt/shared # cat hello                            ======> nothing
laptop:/mnt/shared # uname -r
3.16.7-21-desktop
===

Did I do something wrong? If I misunderstand, please correct me.
Thanks.

 >>>
> A simplified test case is (this case from Ryan): 
> 1) dd if=/dev/zero of=/mnt/hello bs=512 count=1 oflag=direct; 
> 2) truncate /mnt/hello -s 2097152 
> file 'hello' is not exist before test. After this command, 
> file 'hello' should be all zero. But 512~4096 is some random data. 
>  
> Setting bh state to new when get a new block, if so, 
> direct_io_worker()->dio_zero_block() will fill-in the unused portion 
> of the block with zero. 
>  
> Signed-off-by: Yiwen Jiang <jiangyiwen at huawei.com> 
> --- 
>  fs/ocfs2/aops.c | 1 + 
>  1 file changed, 1 insertion(+) 
>  
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c 
> index 1a35c61..bd106b9 100644 
> --- a/fs/ocfs2/aops.c 
> +++ b/fs/ocfs2/aops.c 
> @@ -581,6 +581,7 @@ static int ocfs2_direct_IO_get_blocks(struct inode  
> *inode, sector_t iblock, 
>  			ret = -EIO; 
>  			goto bail; 
>  		} 
> +		set_buffer_new(bh_result); 
>  	} 
>  
>  	/* 
 



--
Eric, Ren