[PATCH] btrfs-progs: create helper function to use lblkid to scan for btrfs disks

[Anand Jain <anand.jain@oracle.com>]

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 utils.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 utils.h |  2 ++
 2 files changed, 56 insertions(+)

diff --git a/utils.c b/utils.c
index c6022fc..ccb5199 100644
--- a/utils.c
+++ b/utils.c
@@ -1914,6 +1914,57 @@ int test_dev_for_mkfs(char *file, int force_overwrite, char *estr)
 	return 0;
 }
 
+int test_skip_this_disk(char *path)
+{
+	int fd;
+	/* this will eliminate disks which are mounted (btrfs)
+	 * and non-dm disk path when dm is enabled
+	 */
+	fd = open(path, O_RDWR|O_EXCL);
+	if (fd < 0)
+		return 1;
+	close(fd);
+	return 0;
+}
+
+int btrfs_scan_lblkid(int update_kernel)
+{
+	int fd = -1;
+	u64 num_devices;
+	struct btrfs_fs_devices *tmp_devices;
+	blkid_dev_iterate iter = NULL;
+	blkid_dev dev = NULL;
+	blkid_cache cache = NULL;
+	char path[PATH_MAX];
+
+	if (blkid_get_cache(&cache, 0) < 0) {
+		printf("ERROR: lblkid cache get failed\n");
+		return 1;
+	}
+	blkid_probe_all(cache);
+	iter = blkid_dev_iterate_begin(cache);
+	blkid_dev_set_search(iter, "TYPE", "btrfs");
+	while (blkid_dev_next(iter, &dev) == 0) {
+		dev = blkid_verify(cache, dev);
+		if (!dev)
+			continue;
+		/* if we are here its definitly a btrfs disk*/
+		strcpy(path, blkid_dev_devname(dev));
+		if (test_skip_this_disk(path))
+			continue;
+
+		fd = open(path, O_RDONLY);
+		btrfs_scan_one_device(fd, path, &tmp_devices,
+				&num_devices, BTRFS_SUPER_INFO_OFFSET);
+		close(fd);
+		fd = -1;
+		if (update_kernel)
+			btrfs_register_one_device(path);
+	}
+	blkid_dev_iterate_end(iter);
+	return 0;
+}
+
 /*
  * scans devs for the btrfs
 */
@@ -1928,6 +1979,9 @@ int scan_for_btrfs(int where, int update_kernel)
 	case BTRFS_SCAN_DEV:
 		ret = btrfs_scan_one_dir("/dev", update_kernel);
 		break;
+	case BTRFS_SCAN_LBLKID:
+		ret = btrfs_scan_lblkid(update_kernel);
+		break;
 	}
 	return ret;
 }
diff --git a/utils.h b/utils.h
index e944685..0f31db7 100644
--- a/utils.h
+++ b/utils.h
@@ -28,6 +28,7 @@
 #define BTRFS_SCAN_PROC		(1ULL << 0)
 #define BTRFS_SCAN_DEV		(1ULL << 1)
 #define BTRFS_SCAN_MOUNTED	(1ULL << 2)
+#define BTRFS_SCAN_LBLKID	(1ULL << 3)
 
 #define BTRFS_UPDATE_KERNEL	1
 
@@ -89,5 +90,6 @@ int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
 			   int verify);
 int ask_user(char *question);
 int lookup_ino_rootid(int fd, u64 *rootid);
+int btrfs_scan_lblkid(int update_kernel);
 
 #endif
-- 
1.8.4.rc4.1.g0d8beaa