There are a couple new block layer commands we are trying to add support for in the near term: compare and write http://www.spinics.net/lists/target-devel/msg07826.html copy offload/extended copy/xcopy https://www.redhat.com/archives/dm-devel/2014-July/msg00070.html The problem is if we contine to add more commands we will have to one day extend the cmd_flags/bi_rw fields again. To prevent that, this patchset separates the operation (REQ_WRITE, REQ_DISCARD, REQ_WRITE_SAME, etc) from the flags (REQ_SYNC, REQ_QUIET, etc) in the bio and request structs. In the end of this set, we will have two fields bio->bi_op/request->op and bio->bi_rw/request->cmd_flags. The patches were made against Jens's linux-block tree's for-linus branch: https://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git/log/?h=for-linus (last commit a22c4d7e34402ccdf3414f64c50365436eba7b93). I have done some basic testing for a lot of the drivers and filesystems, but I wanted to get comments before trying to track down more hardware/ systems for testing. Known issues: - REQ_FLUSH is still a flag, but should probably be a operation. For lower level drivers like SCSI where we only get a flush, it makes more sense to be a operation. However, upper layers like filesystems can send down flushes with writes, so it is more of a flag for them. I am still working on this. - There is a regression with the dm flakey target. It currently cannot corrupt the operation values. - The patchset is a little awkward. It touches so much code, but I wanted to maintain git bisectibility, so there is lots of compat code left around until the last patches where everyting is cleaned up. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
