[RFC PATCH 0/3] realize dax_operations for dm-snapshot

From: Huaisheng Ye <yehs1(a)lenovo.com&gt; This series patches are used to realize the dax_operations for dm-snapshot with persistent memory device. Here are the steps about how to verify the function. 1. Configure the persistent memory to fs-dax mode and create namespace with ndctl; 2. find them in /dev; # ndctl list { "dev":"namespace0.0", "mode":"fsdax", "map":"dev", "size":132118478848, "sector_size":512, "blockdev":"pmem0", "name":"yhs_pmem0", "numa_node":0 }, 3. create lv_pmem (here is 4G size) for testing; # pvcreate /dev/pmem0 # vgcreate vg_pmem /dev/pmem0 # lvcreate -L 4G -n lv_pmem vg_pmem 4. create filesystem (ext2 or ext4) to /dev/pmem0 # mkfs.ext2 -b 4096 /dev/vg_pmem/lv_pmem 5. mount pmem with DAX way; # mkdir /mnt/lv_pmem # mount -o dax /dev/vg_pmem/lv_pmem /mnt/lv_pmem/ 6. cp some files to /mnt/lv_pmem; # cp linear_table03.log /mnt/lv_pmem/ # cp test0.log /mnt/lv_pmem/ 7. create snapshot for test (here I limit it to 1G size); # lvcreate -L 1G -n snap_pmem -s /dev/vg_pmem/lv_pmem 8. modify the files copied with vim or copy more other new files; # vim /mnt/lv_pmem/test0.log 9. umount the pmem device; # umount /mnt/lv_pmem/ 10.merge the snapshot back to origin; # lvconvert --merge /dev/vg_pmem/snap_pmem 11.mount pmem device again for checking the content of files; # mount -o dax /dev/vg_pmem/lv_pmem /mnt/lv_pmem/ Huaisheng Ye (3): dm: enable dax_operations for dm-snapshot dm: expand hc_map in mapped_device for lack of map dm: expand valid types for dm-ioctl drivers/md/dm-core.h | 1 + drivers/md/dm-ioctl.c | 4 +++- drivers/md/dm-snap.c | 44 ++++++++++++++++++++++++++++++++++++++++++-- drivers/md/dm.c | 15 +++++++++++++++ 4 files changed, 61 insertions(+), 3 deletions(-) -- 1.8.3.1