Re: mm: WARNING in __delete_from_page_cache

[Matthew Wilcox]

On Tue, Jan 26, 2016 at 03:42:34AM +0000, Williams, Dan J wrote:
> @@ -2907,7 +2912,12 @@ extern void replace_mount_options(struct super_block *sb, char *options);
>  
>  static inline bool io_is_direct(struct file *filp)
>  {
> -	return (filp->f_flags & O_DIRECT) || IS_DAX(file_inode(filp));

I think this should just be a one-liner:

-	return (filp->f_flags & O_DIRECT) || IS_DAX(file_inode(filp));
+	return (filp->f_flags & O_DIRECT) || IS_DAX(filp->f_mapping->host);

This does the right thing for block device inodes and filesystem inodes.
(see the opening stanzas of __dax_fault for an example).