Btrfs changes in Linux 4.10 aren't as exciting as some would have hoped for, including I. What there is to find with the Btrfs changes in Linux 4.10 are a set of clean-ups, corrections to make Btrfs use proper helpers for bio walking, and several fixes. The fixes do include some "long standing bugs" around btrfs_drop_extents and during the balance operation.
What makes the Btrfs updates for Linux 4.10 a bit less exciting is that it doesn't have a proper/full fix yet for the RAID 5/6 issue and the long-standing possible data corruption bug that is admittedly low-urgency but deals with reading a file with a hole positioned after an inline extent returning uninitalized memory when using Btrfs with zlib compression.
A list of the Btrfs changes that did make it for the Linux 4.10 merge window can be found via this pull request.