[PATCH 7/7] btrfs-progs: add -O comp= option for btrfs-convert

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

User may want to convert the FS to a minimum kernel version. As they may need
to use btrfs on a set of known kernel versions. And have the disk layout compatible.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 btrfs-convert.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/btrfs-convert.c b/btrfs-convert.c
index b0a998b..01b8940 100644
--- a/btrfs-convert.c
+++ b/btrfs-convert.c
@@ -2879,6 +2879,8 @@ static void print_usage(void)
 	printf("\t-L|--copy-label        use label from converted filesystem\n");
 	printf("\t-p|--progress          show converting progress (default)\n");
 	printf("\t-O|--features LIST     comma separated list of filesystem features\n");
+	printf("\t                         use '-O list-all' to list features\n");
+	printf("\t                         use '-O comp=<x.y>|<x.y.z>' x.y.z is the minimum kernel version to be supported\n");
 	printf("\t--no-progress          show only overview, not the detailed progress\n");
 }
 
@@ -2970,6 +2972,24 @@ int main(int argc, char *argv[])
 			case 'O': {
 				char *orig = strdup(optarg);
 				char *tmp = orig;
+				char *tok;
+
+				tok = strtok(tmp, "=");
+				if (!strcmp(tok, "comp")) {
+					tok = strtok(NULL, "=");
+					if (!tok) {
+						fprintf(stderr,
+				"Provide a version for 'comp=' option, ref to 'mkfs.btrfs -O list-all'\n");
+						exit(1);
+					}
+					if (btrfs_features_allowed_by_version(tok, &features) < 0) {
+						fprintf(stderr, "Wrong version format: '%s'\n", tok);
+						exit(1);
+					}
+					features &= BTRFS_MKFS_DEFAULT_FEATURES;
+					goto cont;
+				}
+				tmp = orig;
 
 				tmp = btrfs_parse_fs_features(tmp, &features);
 				if (tmp) {
@@ -2979,6 +2999,7 @@ int main(int argc, char *argv[])
 					free(orig);
 					exit(1);
 				}
+cont:
 				free(orig);
 				if (features & BTRFS_FEATURE_LIST_ALL) {
 					btrfs_list_all_fs_features(
-- 
2.6.2