This patchset has to goals. The first is to be able to reserve memory (bio, bio vec and pages), for REQ_TYPE_BLOCK_PC commands. This is needed for multipath where we need to make forward progress when failing over the device. And it is needed if all the paths are failed and we need userspace or the scsi layer to send IO. Userspace multipathd does path testing and userspace and the scsi layer send commands that are needed to setup new devices (if dev_loss_tmo fires and devices are removed, we need to be able to readd them). The second goal is to convert sg, st and osst to the blk and bio layer helpers to map and copy data. I am not done testing the patchset. The first two patches are ok and are pretty safe since they only add biosets to the bio layer. 0005-have-block-scsi_ioctl-user-GFP_NOIO.patch, 0006-use-GFP_NOIO-in-dm-rdac.patch and 0007-fix-blk_rq_map_user_iov-bounce-code.patch are also pretty safe, but they are built on other patches since I noticed them while testing my patches and I can rediff them. Since the last time I sent the patches, I killed the bio_reserve_buffer junk and replaced it with biosets and a mempool. And before I finish up testing and start on st, I wanted to get comments since I am pretty happy overall with the patches. I want to figure out better names for the functions and maybe merge some other functions like the blk_rq_map_iov with the old blk_map_user, but I can at least do the latter in another patch. My only major bug concern is if blk_copy_user_iov only works for request that go to the scsi layer. In the original code, bio_copy_user copied the bv_len to a second struct, but for requests going to the scsi layer this is not needed because we always complete the whole request in one call (__end_that request will never modify bv_len and do a recalc). I am not done grepping through the other possble users like IDE. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
