This is an effort to use iomap with btrfs. This would keep most responsibility of page handling during writes in iomap code, hence code reduction. For CoW support, changes are needed in iomap code to make sure we perform a copy before the write. This is in line with the discussion we had during adding dax support in btrfs. Efforts on adding dax support have been put on hold until MM experts can come with a way of performing multiple mappings to a single page (primarily the TODO before dax_associate_entry()). While we are waiting on that we could add support for buffered writes in btrfs. I have managed to add Direct I/O with iomap support as well, but it still needs to be refined with respect to locking. If you are interested in that effort (on top of this one), it is available at [1]. [1] https://github.com/goldwynr/linux/tree/btrfs-iomap fs/btrfs/Makefile | 2 fs/btrfs/ctree.h | 1 fs/btrfs/file.c | 468 -------------------------------------------------- fs/btrfs/iomap.c | 430 +++++++++++++++++++++++++++++++++++++++++++++ fs/dax.c | 8 fs/ext2/inode.c | 2 fs/ext4/inode.c | 2 fs/gfs2/bmap.c | 3 fs/internal.h | 2 fs/iomap.c | 45 ++-- fs/xfs/xfs_iomap.c | 9 include/linux/iomap.h | 7 12 files changed, 479 insertions(+), 500 deletions(-)
