From d4610456cfa412811b749f6215b9adae976ab4c3 Mon Sep 17 00:00:00 2001 From: Coly Li Date: Sat, 9 Feb 2019 12:52:56 +0800 Subject: [PATCH] bcache: export backing_dev_uuid via sysfs 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 Signed-off-by: Jens Axboe --- 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 b9166ee..9be27b2 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); -- 2.7.4