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bcache: export backing_dev_uuid via sysfs

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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@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Coly Li 2019-02-09 12:52:56 +08:00 committed by Jens Axboe
parent 926d19465b
commit d4610456cf
1 changed files with 9 additions and 0 deletions
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9
drivers/md/bcache/sysfs.c
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@ -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);