On 2021/5/14 上午7:06, David Sterba wrote:

On Wed, Apr 28, 2021 at 07:03:14AM +0800, Qu Wenruo wrote:

quoted

+	inode = BTRFS_I(page->mapping->host);

This is an unrelated comment to the subpage patchset itself, but I've
seen so many page->mapping->host that I think we should add helpers
wrapping all that, eg. page_to_fs_info or page_to_inode or
bio_to_fs_info etc.

That makes sense.

In fact the usage of page->mapping is never ensured to be safe.
Especially for DIO pages.

Thus a proper helper with extra ASSERT() for page->mapping is always a
good idea.

Thanks,
Qu

quoted

-	TP_printk_btrfs("root=%llu(%s) ino=%llu page_index=%lu start=%llu "
+	TP_printk_btrfs("root=%llu(%s) ino=%llu start=%llu "

I don't think the page index is useful, so it's fine to remove it IMO.