RE: FAILED: patch "[PATCH] ext4: fix data exposure after a crash" failed to apply to 3.14-stable tree

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Hi backports team,

Could you please apply the below patch to the 3.14-stable tree ?

Thanks.
Best regards

 Weller HUANG



> -----Original Message-----
> From: gregkh@xxxxxxxxxxxxxxxxxxx [mailto:gregkh@xxxxxxxxxxxxxxxxxxx]
> Sent: Sunday, June 05, 2016 5:47 AM
> To: jack@xxxxxxx; HUANG Weller (CM/ESW12-CN)
> <Weller.Huang@xxxxxxxxxxxx>; tytso@xxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Subject: FAILED: patch "[PATCH] ext4: fix data exposure after a crash" failed to
> apply to 3.14-stable tree
> 
> 
> The patch below does not apply to the 3.14-stable tree.
> If someone wants it applied there, or to any other stable or longterm tree, then
> please email the backport, including the original git commit id to
> <stable@xxxxxxxxxxxxxxx>.
> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
> From 06bd3c36a733ac27962fea7d6f47168841376824 Mon Sep 17 00:00:00 2001
> From: Jan Kara <jack@xxxxxxx>
> Date: Sun, 24 Apr 2016 00:56:03 -0400
> Subject: [PATCH] ext4: fix data exposure after a crash
> 
> Huang has reported that in his powerfail testing he is seeing stale block contents in
> some of recently allocated blocks although he mounts
> ext4 in data=ordered mode. After some investigation I have found out that indeed
> when delayed allocation is used, we don't add inode to transaction's list of inodes
> needing flushing before commit. Originally we were doing that but commit
> f3b59291a69d removed the logic with a flawed argument that it is not needed.
> 
> The problem is that although for delayed allocated blocks we write their contents
> immediately after allocating them, there is no guarantee that the IO scheduler or
> device doesn't reorder things and thus transaction allocating blocks and attaching
> them to inode can reach stable storage before actual block contents. Actually
> whenever we attach freshly allocated blocks to inode using a written extent, we
> should add inode to transaction's ordered inode list to make sure we properly wait
> for block contents to be written before committing the transaction. So that is what
> we do in this patch. This also handles other cases where stale data exposure was
> possible - like filling hole via mmap in data=ordered,nodelalloc mode.
> 
> The only exception to the above rule are extending direct IO writes where
> blkdev_direct_IO() waits for IO to complete before increasing i_size and thus stale
> data exposure is not possible. For now we don't complicate the code with
> optimizing this special case since the overhead is pretty low. In case this is
> observed to be a performance problem we can always handle it using a special
> flag to ext4_map_blocks().
> 
> CC: stable@xxxxxxxxxxxxxxx
> Fixes: f3b59291a69d0b734be1fc8be489fef2dd846d3d
> Reported-by: "HUANG Weller (CM/ESW12-CN)" <Weller.Huang@xxxxxxxxxxxx>
> Tested-by: "HUANG Weller (CM/ESW12-CN)" <Weller.Huang@xxxxxxxxxxxx>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 981a1fc30eaa..250c2df04a92
> 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -684,6 +684,21 @@ out_sem:
>  		ret = check_block_validity(inode, map);
>  		if (ret != 0)
>  			return ret;
> +
> +		/*
> +		 * Inodes with freshly allocated blocks where contents will be
> +		 * visible after transaction commit must be on transaction's
> +		 * ordered data list.
> +		 */
> +		if (map->m_flags & EXT4_MAP_NEW &&
> +		    !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
> +		    !(flags & EXT4_GET_BLOCKS_ZERO) &&
> +		    !IS_NOQUOTA(inode) &&
> +		    ext4_should_order_data(inode)) {
> +			ret = ext4_jbd2_file_inode(handle, inode);
> +			if (ret)
> +				return ret;
> +		}
>  	}
>  	return retval;
>  }
> @@ -1289,15 +1304,6 @@ static int ext4_write_end(struct file *file,
>  	int i_size_changed = 0;
> 
>  	trace_ext4_write_end(inode, pos, len, copied);
> -	if (ext4_test_inode_state(inode, EXT4_STATE_ORDERED_MODE)) {
> -		ret = ext4_jbd2_file_inode(handle, inode);
> -		if (ret) {
> -			unlock_page(page);
> -			put_page(page);
> -			goto errout;
> -		}
> -	}
> -
>  	if (ext4_has_inline_data(inode)) {
>  		ret = ext4_write_inline_data_end(inode, pos, len,
>  						 copied, page);

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