When there are multiple bcache devices, after a reboot the name of
bcache devices may change (e.g. current /dev/bcache1 was /dev/bcache0
before reboot). Therefore we need the backing device UUID (sb.uuid) to
identify each bcache device.
Backing device uuid can be found by program bcache-super-show, but
directly exporting backing_dev_uuid by sysfs file
/sys/block/bcache<?>/bcache/backing_dev_uuid is a much simpler method.
With backing_dev_uuid, and partition uuids from /dev/disk/by-partuuid/,
now we can identify each bcache device and its partitions conveniently.
Signed-off-by: Coly Li <colyli@xxxxxxx>
---
drivers/md/bcache/sysfs.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index b9166ee027fa..9be27b26d300 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -68,6 +68,7 @@ read_attribute(btree_written);
read_attribute(metadata_written);
read_attribute(active_journal_entries);
read_attribute(backing_dev_name);
+read_attribute(backing_dev_uuid);
sysfs_time_stats_attribute(btree_gc, sec, ms);
sysfs_time_stats_attribute(btree_split, sec, us);
@@ -250,6 +251,13 @@ SHOW(__bch_cached_dev)
return strlen(buf);
}
+ if (attr == &sysfs_backing_dev_uuid) {
+ /* convert binary uuid into 36-byte string plus '\0' */
+ snprintf(buf, 36+1, "%pU", dc->sb.uuid);
+ strcat(buf, "\n");
+ return strlen(buf);
+ }
+
#undef var
return 0;
}
@@ -460,6 +468,7 @@ static struct attribute *bch_cached_dev_files[] = {
&sysfs_bypass_torture_test,
#endif
&sysfs_backing_dev_name,
+ &sysfs_backing_dev_uuid,
NULL
};
KTYPE(bch_cached_dev);
--
2.16.4
