[Ocfs2-devel] [PATCH] ocfs2: avoid direct write if we fall back to buffered

[Sunil Mushran <sunil.mushran@oracle.com>]

I cannot read the bugzilla. Now it maybe that that bz
cannot be made public. That's ok. But if that's the case,
can you explain the problem encountered. I am not qs
the fix... rather trying to understand why this has not
been reported before.

Li Dongyang wrote:
> when we fall back to buffered write from direct write, we call
> __generic_file_aio_write but that will end up doing direct write
> even we are only prepared to do buffered write because the file
> has O_DIRECT flag set. This is a fix for
> https://bugzilla.novell.com/show_bug.cgi?id=591039
>
>
> Signed-off-by: Li Dongyang <lidongyang@novell.com>
> ---
>  fs/ocfs2/file.c |   27 +++++++++++++++++----------
>  1 files changed, 17 insertions(+), 10 deletions(-)
>
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index de059f4..707f2a2 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -1973,18 +1973,24 @@ relock:
>  	/* communicate with ocfs2_dio_end_io */
>  	ocfs2_iocb_set_rw_locked(iocb, rw_level);
>  
> -	if (direct_io) {
> -		ret = generic_segment_checks(iov, &nr_segs, &ocount,
> -					     VERIFY_READ);
> -		if (ret)
> -			goto out_dio;
> +	ret = generic_segment_checks(iov, &nr_segs, &ocount,
> +				     VERIFY_READ);
> +	if (ret)
> +		goto out_dio;
>  
> -		count = ocount;
> -		ret = generic_write_checks(file, ppos, &count,
> +	count = ocount;
> +	ret = generic_write_checks(file, ppos, &count,
>  					   S_ISBLK(inode->i_mode));
> -		if (ret)
> -			goto out_dio;
> +	if (ret)
> +		goto out_dio;
> +
> +	ret = file_remove_suid(file);
> +	if (ret)
> +		goto out_dio;
>  
> +	file_update_time(file);
> +
> +	if (direct_io) {
>  		written = generic_file_direct_write(iocb, iov, &nr_segs, *ppos,
>  						    ppos, count, ocount);
>  		if (written < 0) {
> @@ -1999,7 +2005,8 @@ relock:
>  			goto out_dio;
>  		}
>  	} else {
> -		written = __generic_file_aio_write(iocb, iov, nr_segs, ppos);
> +		written = generic_file_buffered_write(iocb, iov, nr_segs,
> +				*ppos, ppos, count, 0);
>  	}
>  
>  out_dio:
>