[PATCH 0/8 v3] btrfs direct-io using iomap

Goldwyn Rodrigues
2019-12-05T15:56:38Z

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 on xfs/iomap-for-next, though I tested it
against the patches on xfs/iomap-for-next on top of v5.4.1 (there are no
changes to existing patches). The tree is available at
https://github.com/goldwynr/linux/tree/btrfs-iomap-dio

I have tested it against xfstests/btrfs.

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.

fs/btrfs/btrfs_inode.h | 18 ---
fs/btrfs/ctree.h | 1
fs/btrfs/extent_io.c | 37 ++----
fs/btrfs/extent_io.h | 2
fs/btrfs/file.c | 21 +++
fs/btrfs/inode.c | 267 ++++++++++++++++---------------------------------
fs/direct-io.c | 19 ---
fs/iomap/direct-io.c | 16 +-
include/linux/fs.h | 3
include/linux/iomap.h | 2
mm/filemap.c | 13 +-
11 files changed, 149 insertions(+), 250 deletions(-)

--
Goldwyn