Extern or forward variable declaration at include/linux/device-mapper.h, line 19 References: drivers/md/dm-bufio.c, line 149 drivers/md/dm-bufio.c, line 149 drivers/md/dm-bufio.c, line 538 drivers/md/dm-cache-target.c, line 2584 drivers/md/dm-crypt.c, line 684 drivers/md/dm-crypt.c, line 685 drivers/md/dm-crypt.c, line 859 drivers/md/dm-crypt.c, line 1802 drivers/md/dm-flakey.c, line 390 drivers/md/dm-io.c, line 208 drivers/md/dm-io.c, line 208 drivers/md/dm-io.c, line 216 drivers/md/dm-io.c, line 216 drivers/md/dm-io.c, line 220 drivers/md/dm-linear.c, line 133 drivers/md/dm-snap.c, line 2160 drivers/md/dm-stripe.c, line 410 drivers/md/dm-thin.c, line 2617 drivers/md/dm-verity.c, line 77 drivers/md/dm-verity.c, line 83 drivers/md/dm-verity.c, line 340 drivers/md/dm-verity.c, line 528 drivers/md/dm-verity.c, line 589 drivers/md/dm-verity.c, line 865 drivers/md/dm.c, line 1053 drivers/md/dm.c, line 1264 drivers/md/dm.c, line 1397 fs/nfs/blocklayout/blocklayout.c, line 205 fs/nfs/blocklayout/blocklayout.c, line 387 fs/nfs/blocklayout/blocklayout.c, line 492 include/linux/device-mapper.h, line 19 include/linux/device-mapper.h, line 80