xfs: validate bdev support for DAX inode flag

commit 6851a3db7e224bbb85e23b3c64a506c9e0904382 upstream.

Currently only the blocksize is checked, but we should really be calling
bdev_dax_supported() which also tests to make sure we can get a
struct dax_device and that the dax_direct_access() path is working.

This is the same check that we do for the "-o dax" mount option in
xfs_fs_fill_super().

This does not fix the race issues that caused the XFS DAX inode option to
be disabled, so that option will still be disabled.  If/when we re-enable
it, though, I think we will want this issue to have been fixed.  I also do
think that we want to fix this in stable kernels.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index bce2e26..6c95812 100644 (file)
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1085,6 +1085,7 @@ xfs_ioctl_setattr_dax_invalidate(
        int                     *join_flags)
 {
        struct inode            *inode = VFS_I(ip);
+       struct super_block      *sb = inode->i_sb;
        int                     error;
 
        *join_flags = 0;
@@ -1097,7 +1098,7 @@ xfs_ioctl_setattr_dax_invalidate(
        if (fa->fsx_xflags & FS_XFLAG_DAX) {
                if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
                        return -EINVAL;
-               if (ip->i_mount->m_sb.sb_blocksize != PAGE_SIZE)
+               if (bdev_dax_supported(sb, sb->s_blocksize) < 0)
                        return -EINVAL;
        }