[PATCH 2/2] btrfs-progs: add udev rule to forget removed device

[Boris Burkov <boris@bur.io>]

Now that btrfs supports forgetting devices that don't exist, we can add
a udev rule to take advantage of that. This avoids bad edge cases
with cached devices in multi-device filesystems without having to rescan
all the devices on every change.

Signed-of-by: Boris Burkov <boris@bur.io>
---
 64-btrfs-rm.rules | 7 +++++++
 Makefile          | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)
 create mode 100644 64-btrfs-rm.rules

diff --git a/64-btrfs-rm.rules b/64-btrfs-rm.rules
new file mode 100644
index 000000000..852155d28
--- /dev/null
+++ b/64-btrfs-rm.rules
@@ -0,0 +1,7 @@
+SUBSYSTEM!="block", GOTO="btrfs_rm_end"
+ACTION!="remove", GOTO="btrfs_rm_end"
+ENV{ID_FS_TYPE}!="btrfs", GOTO="btrfs_rm_end"
+
+RUN+="/usr/local/bin/btrfs device scan -u $devnode"
+
+LABEL="btrfs_rm_end"
diff --git a/Makefile b/Makefile
index 374f59b99..eaeed9baf 100644
--- a/Makefile
+++ b/Makefile
@@ -271,7 +271,7 @@ tune_objects = tune/main.o tune/seeding.o tune/change-uuid.o tune/change-metadat
 all_objects = $(objects) $(cmds_objects) $(libbtrfs_objects) $(convert_objects) \
 	      $(mkfs_objects) $(image_objects) $(tune_objects) $(libbtrfsutil_objects)
 
-udev_rules = 64-btrfs-dm.rules 64-btrfs-zoned.rules
+udev_rules = 64-btrfs-dm.rules 64-btrfs-zoned.rules 64-btrfs-rm.rules
 
 ifeq ("$(origin V)", "command line")
   BUILD_VERBOSE = $(V)
-- 
2.43.0