Hi all, here's a combined version of the earlier patchset from Sergei, fixing some issues I've found during testing and including (some) feedback from Mike. So with this patchset I could do a echo "0 33554432 linear /dev/sda 0" | dmsetup create sda-cloned on a system with root-fs on /dev/sda2, and things would continue to run just like normal. There are some things which might need to be improved: - I've tried to remove the stub bio clone for the dm interposer as suggested by Mike, but that resulted in an endless recursion in submit_bio_noacct(). That needs more debugging, but I'm also not sure if we _can_ do it; the end_io callback might refer to bi_disk->driver_private, and then will get confused as we've reassigned the 'bi_disk' setting. Not sure if there are fixed rules for it, so for now I'll probably leave it. - The interposer is 'magically' hooked to the first block device in the device-mapper table. What I really want is to have an explicit listing of the interposer in the output of things like 'dmsetup table' like 0 33554432 interposer /dev/dm-0 0 33554432 linear /dev/sda 0 and the first entry having the device number of /dev/sda. Plan was to have that automatically registered once you set up the original table, but then I'm not sure if that's the right way to go. Mike? - The removal of blkdev_get() as an exported API made things awkward, as we now have to do a blkdev_get_by_dev(); if not we end up with an uninitalized blkcg and a resulting crash. We might be able to fix this up by moving bdget() into dm_blk_open(), and have md->bdev uninitalized otherwise. But again I'm not sure if that's the right way to go. Anyway, comments and reviews are welcome. Sergei Shtepa (2): blk_interposer - Block Layer Interposer dm_interposer - blk_interposer for device-mapper block/blk-core.c | 34 +++++++++++ block/genhd.c | 55 ++++++++++++++++++ drivers/md/dm-table.c | 59 +++++++++++++++++++ drivers/md/dm.c | 140 ++++++++++++++++++++++++++++++++++++++++++---- drivers/md/dm.h | 4 +- include/linux/blk_types.h | 6 +- include/linux/genhd.h | 19 +++++++ 7 files changed, 303 insertions(+), 14 deletions(-) -- 2.16.4 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
