Patch "xfs: validate bdev support for DAX inode flag" has been added to the 4.13-stable tree

This is a note to let you know that I've just added the patch titled

xfs: validate bdev support for DAX inode flag

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xfs-validate-bdev-support-for-dax-inode-flag.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ross Zwisler <[email protected]>
Date: Mon, 18 Sep 2017 14:46:03 -0700
Subject: xfs: validate bdev support for DAX inode flag

From: Ross Zwisler <[email protected]>

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.

---
 fs/xfs/xfs_ioctl.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -1088,6 +1088,7 @@ 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;

@@ -1100,7 +1101,7 @@ 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;
 	}
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/xfs-validate-bdev-support-for-dax-inode-flag.patch