linux-kernel - Re: [PATCH 1/2] dax: pass bdev argument to dax_clear

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Message-ID: <20160207220329.GK31407@dastard>
Date:	Mon, 8 Feb 2016 09:03:29 +1100
From:	Dave Chinner <david@...morbit.com>
To:	Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org, Theodore Ts'o <tytso@....edu>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Andreas Dilger <adilger.kernel@...ger.ca>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Williams <dan.j.williams@...el.com>,
	Jan Kara <jack@...e.com>,
	Matthew Wilcox <willy@...ux.intel.com>,
	linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org, linux-nvdimm@...ts.01.org, xfs@....sgi.com
Subject: Re: [PATCH 1/2] dax: pass bdev argument to dax_clear_blocks()

On Sun, Feb 07, 2016 at 12:19:12AM -0700, Ross Zwisler wrote:
> dax_clear_blocks() needs a valid struct block_device and previously it was
> using inode->i_sb->s_bdev in all cases.  This is correct for normal inodes
> on mounted ext2, ext4 and XFS filesystems, but is incorrect for DAX raw
> block devices and for XFS real-time devices.
> 
> Instead, have the caller pass in a struct block_device pointer which it
> knows to be correct.
....
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index 07ef29b..f722ba2 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -73,9 +73,11 @@ xfs_zero_extent(
>  	xfs_daddr_t	sector = xfs_fsb_to_db(ip, start_fsb);
>  	sector_t	block = XFS_BB_TO_FSBT(mp, sector);
>  	ssize_t		size = XFS_FSB_TO_B(mp, count_fsb);
> +	struct inode	*inode = VFS_I(ip);
>  
>  	if (IS_DAX(VFS_I(ip)))
> -		return dax_clear_blocks(VFS_I(ip), block, size);
> +		return dax_clear_blocks(inode, xfs_find_bdev_for_inode(inode),
> +				block, size);

Get rid of the local inode variable and use VFS_I(ip) like the code
originally did. Do not change code that is unrelated to the
modifcation being made, especially when it results in making
the code an inconsistent mess of mixed pointer constructs....

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com