On Mon, Feb 08, 2016 at 09:03:29AM +1100, Dave Chinner wrote:

On Sun, Feb 07, 2016 at 12:19:12AM -0700, Ross Zwisler wrote:

quoted

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.

....

quoted

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....

The local 'inode' variable was added to avoid multiple calls for VFS_I() for
the same 'ip'.  That said, I'm happy to make the change.

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