This is an effort to use iomap for direct I/O in btrfs. This would change the call from __blockdev_direct_io() to iomap_dio_rw(). The main objective is to lose the buffer head and use bio defined by iomap code, and hopefully to use more of generic-FS codebase. These patches are based and tested on v5.5-rc1. I have tested it against xfstests/btrfs. The tree is available at https://github.com/goldwynr/linux/tree/btrfs-iomap-dio Changes since v1 - Incorporated back the efficiency change for inode locking - Review comments about coding style and git comments - Merge related patches into one - Direct read to go through btrfs_direct_IO() - Removal of no longer used function dio_end_io() Changes since v2 - aligning iomap offset/length to the position/length of I/O - Removed btrfs_dio_data - Removed BTRFS_INODE_READDIO_NEED_LOCK - Re-incorporating write efficiency changes caused lockdep_assert() in iomap to be triggered, remove that code. Changes since v3 - Fixed freeze on generic/095. Use iomap_end() to account for failed/incomplete dio instead of btrfs_dio_data Changes since v4 - moved lockdep_assert_held() to functions calling iomap_dio_rw() This may be called immidiately after calling inode lock and may feel not required, but it seems important. - Removed comments which are no longer required - Changed commit comments to make them more appropriate Changes since v5 - restore inode_dio_wait() in truncate - Removed lockdep_assert_held() near callers -- Goldwyn
