Re: [PATCH 2/2] dax: fix bdev NULL pointer dereferences

[Dan Williams]

On Thu, Jan 28, 2016 at 11:35 AM, Ross Zwisler
<ross.zwisler@xxxxxxxxxxxxxxx> wrote:
> There are a number of places in dax.c that look up the struct block_device
> associated with an inode.  Previously this was done by just using
> inode->i_sb->s_bdev.  This is correct for inodes that exist within the
> filesystems supported by DAX (ext2, ext4 & XFS), but when running DAX
> against raw block devices this value is NULL.  This causes NULL pointer
> dereferences when these block_device pointers are used.
>
> Instead, for raw block devices we need to look up the struct block_device
> using I_BDEV().  This patch fixes all the block_device lookups in dax.c so
> that they work properly for both filesystems and raw block devices.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>

It's a bit odd to check if it is a raw device inode in
dax_clear_blocks() since there's no use case to clear blocks in that
case, but I can't think of a better alternative.

Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx>