Re: [PATCH 3/8] iomap: Move lockdep_assert_held() to iomap_dio_rw() calls

From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: linux-btrfs@vger.kernel.org, hch@infradead.org,
	fdmanana@kernel.org, nborisov@suse.com, dsterba@suse.cz,
	jthumshirn@suse.de, linux-fsdevel@vger.kernel.org,
	Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 3/8] iomap: Move lockdep_assert_held() to iomap_dio_rw() calls
Date: Fri, 13 Dec 2019 16:32:32 -0800	[thread overview]
Message-ID: <20191214003232.GB99860@magnolia> (raw)
In-Reply-To: <20191213195750.32184-4-rgoldwyn@suse.de>

On Fri, Dec 13, 2019 at 01:57:45PM -0600, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Filesystems such as btrfs can perform direct I/O without holding the
> inode->i_rwsem in some of the cases like writing within i_size.
> So, remove the check for lockdep_assert_held() in iomap_dio_rw()
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

Mildly scary, but OTOH filesystems are supposed to take care of their
own locking before calling iomap...

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/iomap/direct-io.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 1a3bf3bd86fb..41c1e7c20a1f 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -415,8 +415,6 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
>  	struct blk_plug plug;
>  	struct iomap_dio *dio;
>  
> -	lockdep_assert_held(&inode->i_rwsem);
> -
>  	if (!count)
>  		return 0;
>  
> -- 
> 2.16.4
> 