[2/5] 'btrfs device scan' skips lvm snapshots.

Commit Message

Goffredo Baroncelli Dec. 4, 2014, 6:39 p.m. UTC

LVM snapshots create a problem to the btrfs devices management.
BTRFS assumes that each device has an unique 'device UUID'.
A LVM snapshot breaks this assumption.

With this patch, 'btrfs device scan' skips LVM snapshot.
If you need to consider a LVM snapshot you have to pass the '-s' switch
ot set the environment variable BTRFS_SKIP_LVM_SNAPSHOT to "no".

Signed-off-by: Goffredo Baroncelli <[e-mail]>
---
 cmds-device.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

Patch

diff --git a/cmds-device.c b/cmds-device.c
index 6cd41e1..f6c76e7 100644
--- a/cmds-device.c
+++ b/cmds-device.c
@@ -197,9 +197,10 @@  static int cmd_rm_dev(int argc, char **argv)
 }
 
 static const char * const cmd_scan_dev_usage[] = {
-	"btrfs device scan [(-d|--all-devices)|<device> [<device>...]]",
+	"btrfs device scan [-s][(-d|--all-devices)|<device> [<device>...]]",
 	"Scan devices for a btrfs filesystem",
 	" -d|--all-devices (deprecated)",
+	" -s                               don't skip lvm snapshot\n",
 	NULL
 };
 
@@ -209,6 +210,7 @@  static int cmd_scan_dev(int argc, char **argv)
 	int devstart = 1;
 	int all = 0;
 	int ret = 0;
+	int skip_snapshot = btrfs_scan_get_skip_lvm_snapshot();
 
 	optind = 1;
 	while (1) {
@@ -217,7 +219,7 @@  static int cmd_scan_dev(int argc, char **argv)
 			{ "all-devices", no_argument, NULL, 'd'},
 			{ 0, 0, 0, 0 },
 		};
-		int c = getopt_long(argc, argv, "d", long_options,
+		int c = getopt_long(argc, argv, "sd", long_options,
 				    &long_index);
 		if (c < 0)
 			break;
@@ -225,6 +227,10 @@  static int cmd_scan_dev(int argc, char **argv)
 		case 'd':
 			all = 1;
 			break;
+		case 's':
+			skip_snapshot = 0;
+			devstart++;
+			break;
 		default:
 			usage(cmd_scan_dev_usage);
 		}
@@ -233,7 +239,7 @@  static int cmd_scan_dev(int argc, char **argv)
 	if (all && check_argc_max(argc, 2))
 		usage(cmd_scan_dev_usage);
 
-	if (all || argc == 1) {
+	if (all || argc == devstart) {
 		printf("Scanning for Btrfs filesystems\n");
 		ret = btrfs_scan_lblkid();
 		if (ret)
@@ -261,6 +267,11 @@  static int cmd_scan_dev(int argc, char **argv)
 			ret = 1;
 			goto out;
 		}
+		if (skip_snapshot && is_low_priority_device(path)) {
+			fprintf(stderr, "WARNING: skip device '%s' because it is a snapshot\n",
+				argv[i]);
+			continue;
+		}
 		printf("Scanning for Btrfs filesystems in '%s'\n", path);
 		if (btrfs_register_one_device(path) != 0) {
 			ret = 1;