zygo: cherry-picked up to linus/master --remotes=btrfs-next/* --remotes=mason/* ...

Commits included (++++) and excluded (----):

---- 2b0143b VFS: normal filesystems (and lustre): d_inode() annotations
---- fe0f07d direct-io: only inc/dec inode->i_dio_count for file systems
++++ b58d1a9 Btrfs: fix race between start dirty bg cache writeout and bg deletion
++++ 24b89d0 Btrfs: fix deadlock when starting writeback of bg caches
---- e4c88f0 Btrfs: don't check for delalloc_bytes in cache_save_setup
---- 1b98450 Btrfs: fix find_free_dev_extent() malfunction in case device tree has hole
---- 67b7859 btrfs: handle ENOMEM in btrfs_alloc_tree_block
---- 5ca64f4 btrfs: fix race on ENOMEM in alloc_extent_buffer
---- b860545 btrfs: check io_ctl_prepare_pages return in __btrfs_write_out_cache
---- 909e26d btrfs: unlock i_mutex after attempting to delete subvolume during send
---- 6e17d30 Btrfs: fill ->last_trans for delayed inode in btrfs_fill_inode.