diff --git a/Documentation/mkfs.btrfs.asciidoc b/Documentation/mkfs.btrfs.asciidoc
index 12d8840..5c5b41d 100644
--- a/Documentation/mkfs.btrfs.asciidoc
+++ b/Documentation/mkfs.btrfs.asciidoc
@@ -207,6 +207,15 @@ reduced-size metadata for extent references, saves a few percent of metadata
 improved representation of file extents where holes are not explicitly
 stored as an extent, saves a few percent of metadata if sparse files are used
 
+*dedup*::
+allow btrfs to use new on-disk format designed for in-band(write time)
+de-duplication.
++
+on-disk storage backend and persist de-duplication status needs this feature.
++
+unlike other features, this is an RO compat flag, means old kernel can still
+mount fs read-only.
+
 BLOCK GROUPS, CHUNKS, RAID
 --------------------------
 
diff --git a/btrfs-convert.c b/btrfs-convert.c
index 02e5cdb..bf1df48 100644
--- a/btrfs-convert.c
+++ b/btrfs-convert.c
@@ -2288,7 +2288,7 @@ err:
 
 static int do_convert(const char *devname, int datacsum, int packing, int noxattr,
 		u32 nodesize, int copylabel, const char *fslabel, int progress,
-		u64 features)
+		u64 features, u64 ro_features)
 {
 	int i, ret, blocks_per_node;
 	int fd = -1;
@@ -2343,8 +2343,9 @@ static int do_convert(const char *devname, int datacsum, int packing, int noxatt
 		fprintf(stderr, "unable to open %s\n", devname);
 		goto fail;
 	}
-	btrfs_parse_features_to_string(features_buf, features);
-	if (features == BTRFS_MKFS_DEFAULT_FEATURES)
+	btrfs_parse_features_to_string(features_buf, features, ro_features);
+	if (features == BTRFS_MKFS_DEFAULT_FEATURES &&
+	    ro_features == 0)
 		strcat(features_buf, " (default)");
 
 	printf("create btrfs filesystem:\n");
@@ -2360,6 +2361,7 @@ static int do_convert(const char *devname, int datacsum, int packing, int noxatt
 	mkfs_cfg.sectorsize = blocksize;
 	mkfs_cfg.stripesize = blocksize;
 	mkfs_cfg.features = features;
+	mkfs_cfg.ro_features = ro_features;
 
 	ret = make_btrfs(fd, &mkfs_cfg);
 	if (ret) {
@@ -2898,6 +2900,7 @@ int main(int argc, char *argv[])
 	char *file;
 	char fslabel[BTRFS_LABEL_SIZE];
 	u64 features = BTRFS_MKFS_DEFAULT_FEATURES;
+	u64 ro_features = 0;
 
 	while(1) {
 		enum { GETOPT_VAL_NO_PROGRESS = 256 };
@@ -2956,7 +2959,8 @@ int main(int argc, char *argv[])
 				char *orig = strdup(optarg);
 				char *tmp = orig;
 
-				tmp = btrfs_parse_fs_features(tmp, &features);
+				tmp = btrfs_parse_fs_features(tmp, &features,
+							      &ro_features);
 				if (tmp) {
 					fprintf(stderr,
 						"Unrecognized filesystem feature '%s'\n",
@@ -2974,7 +2978,9 @@ int main(int argc, char *argv[])
 					char buf[64];
 
 					btrfs_parse_features_to_string(buf,
-						features & ~BTRFS_CONVERT_ALLOWED_FEATURES);
+						features &
+						~BTRFS_CONVERT_ALLOWED_FEATURES,
+						ro_features);
 					fprintf(stderr,
 						"ERROR: features not allowed for convert: %s\n",
 						buf);
@@ -3025,7 +3031,8 @@ int main(int argc, char *argv[])
 		ret = do_rollback(file);
 	} else {
 		ret = do_convert(file, datacsum, packing, noxattr, nodesize,
-				copylabel, fslabel, progress, features);
+				copylabel, fslabel, progress, features,
+				ro_features);
 	}
 	if (ret)
 		return 1;
diff --git a/mkfs.c b/mkfs.c
index 5f1411f..9c7acc2 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -1372,6 +1372,7 @@ int main(int ac, char **av)
 	int saved_optind;
 	char fs_uuid[BTRFS_UUID_UNPARSED_SIZE] = { 0 };
 	u64 features = BTRFS_MKFS_DEFAULT_FEATURES;
+	u64 ro_features = 0;
 	struct mkfs_allocation allocation = { 0 };
 	struct btrfs_mkfs_config mkfs_cfg;
 
@@ -1434,7 +1435,8 @@ int main(int ac, char **av)
 				char *orig = strdup(optarg);
 				char *tmp = orig;
 
-				tmp = btrfs_parse_fs_features(tmp, &features);
+				tmp = btrfs_parse_fs_features(tmp, &features,
+							      &ro_features);
 				if (tmp) {
 					fprintf(stderr,
 						"Unrecognized filesystem feature '%s'\n",
@@ -1677,6 +1679,7 @@ int main(int ac, char **av)
 	mkfs_cfg.sectorsize = sectorsize;
 	mkfs_cfg.stripesize = stripesize;
 	mkfs_cfg.features = features;
+	mkfs_cfg.ro_features = ro_features;
 
 	ret = make_btrfs(fd, &mkfs_cfg);
 	if (ret) {
@@ -1831,7 +1834,8 @@ raid_groups:
 			btrfs_group_profile_str(metadata_profile),
 			pretty_size(allocation.system));
 		printf("SSD detected:       %s\n", ssd ? "yes" : "no");
-		btrfs_parse_features_to_string(features_buf, features);
+		btrfs_parse_features_to_string(features_buf, features,
+					       ro_features);
 		printf("Incompat features:  %s", features_buf);
 		printf("\n");
 
diff --git a/utils.c b/utils.c
index 60235d8..6b0c67a 100644
--- a/utils.c
+++ b/utils.c
@@ -250,6 +250,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
 	btrfs_set_super_chunk_root_generation(&super, 1);
 	btrfs_set_super_cache_generation(&super, -1);
 	btrfs_set_super_incompat_flags(&super, cfg->features);
+	btrfs_set_super_compat_ro_flags(&super, cfg->ro_features);
 	if (cfg->label)
 		strncpy(super.label, cfg->label, BTRFS_LABEL_SIZE - 1);
 
@@ -572,23 +573,26 @@ out:
 static const struct btrfs_fs_feature {
 	const char *name;
 	u64 flag;
+	u64 ro_flag;
 	const char *desc;
 } mkfs_features[] = {
-	{ "mixed-bg", BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS,
+	{ "mixed-bg", BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS, 0,
 		"mixed data and metadata block groups" },
-	{ "extref", BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF,
+	{ "extref", BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF, 0,
 		"increased hardlink limit per file to 65536" },
-	{ "raid56", BTRFS_FEATURE_INCOMPAT_RAID56,
+	{ "raid56", BTRFS_FEATURE_INCOMPAT_RAID56, 0,
 		"raid56 extended format" },
-	{ "skinny-metadata", BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA,
+	{ "skinny-metadata", BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA, 0,
 		"reduced-size metadata extent refs" },
-	{ "no-holes", BTRFS_FEATURE_INCOMPAT_NO_HOLES,
+	{ "no-holes", BTRFS_FEATURE_INCOMPAT_NO_HOLES, 0,
 		"no explicit hole extents for files" },
+	{ "dedup", 0, BTRFS_FEATURE_COMPAT_RO_DEDUP,
+		"support on-disk dedup backend and persist dedup status" },
 	/* Keep this one last */
-	{ "list-all", BTRFS_FEATURE_LIST_ALL, NULL }
+	{ "list-all", BTRFS_FEATURE_LIST_ALL, 0, NULL }
 };
 
-static int parse_one_fs_feature(const char *name, u64 *flags)
+static int parse_one_fs_feature(const char *name, u64 *flags, u64 *ro_flags)
 {
 	int i;
 	int found = 0;
@@ -597,9 +601,11 @@ static int parse_one_fs_feature(const char *name, u64 *flags)
 		if (name[0] == '^' &&
 			!strcmp(mkfs_features[i].name, name + 1)) {
 			*flags &= ~ mkfs_features[i].flag;
+			*ro_flags &= ~mkfs_features[i].ro_flag;
 			found = 1;
 		} else if (!strcmp(mkfs_features[i].name, name)) {
 			*flags |= mkfs_features[i].flag;
+			*ro_flags |= mkfs_features[i].ro_flag;
 			found = 1;
 		}
 	}
@@ -607,7 +613,7 @@ static int parse_one_fs_feature(const char *name, u64 *flags)
 	return !found;
 }
 
-void btrfs_parse_features_to_string(char *buf, u64 flags)
+void btrfs_parse_features_to_string(char *buf, u64 flags, u64 ro_flags)
 {
 	int i;
 
@@ -619,10 +625,15 @@ void btrfs_parse_features_to_string(char *buf, u64 flags)
 				strcat(buf, ", ");
 			strcat(buf, mkfs_features[i].name);
 		}
+		if (ro_flags & mkfs_features[i].ro_flag) {
+			if (*buf)
+				strcat(buf, ", ");
+			strcat(buf, mkfs_features[i].name);
+		}
 	}
 }
 
-void btrfs_process_fs_features(u64 flags)
+void btrfs_process_fs_features(u64 flags, u64 ro_flags)
 {
 	int i;
 
@@ -632,6 +643,11 @@ void btrfs_process_fs_features(u64 flags)
 				mkfs_features[i].name,
 				mkfs_features[i].desc);
 		}
+		if (ro_flags & mkfs_features[i].ro_flag) {
+			printf("Turning ON RO compat features '%s': %s\n",
+				mkfs_features[i].name,
+				mkfs_features[i].desc);
+		}
 	}
 }
 
@@ -659,7 +675,7 @@ void btrfs_list_all_fs_features(u64 mask_disallowed)
  * Return NULL if all features were parsed fine, otherwise return the name of
  * the first unparsed.
  */
-char* btrfs_parse_fs_features(char *namelist, u64 *flags)
+char *btrfs_parse_fs_features(char *namelist, u64 *flags, u64 *ro_flags)
 {
 	char *this_char;
 	char *save_ptr = NULL; /* Satisfy static checkers */
@@ -667,7 +683,7 @@ char* btrfs_parse_fs_features(char *namelist, u64 *flags)
 	for (this_char = strtok_r(namelist, ",", &save_ptr);
 	     this_char != NULL;
 	     this_char = strtok_r(NULL, ",", &save_ptr)) {
-		if (parse_one_fs_feature(this_char, flags))
+		if (parse_one_fs_feature(this_char, flags, ro_flags))
 			return this_char;
 	}
 
diff --git a/utils.h b/utils.h
index b625330..835fd22 100644
--- a/utils.h
+++ b/utils.h
@@ -102,9 +102,9 @@ void units_set_mode(unsigned *units, unsigned mode);
 void units_set_base(unsigned *units, unsigned base);
 
 void btrfs_list_all_fs_features(u64 mask_disallowed);
-char* btrfs_parse_fs_features(char *namelist, u64 *flags);
-void btrfs_process_fs_features(u64 flags);
-void btrfs_parse_features_to_string(char *buf, u64 flags);
+char *btrfs_parse_fs_features(char *namelist, u64 *flags, u64 *ro_flags);
+void btrfs_process_fs_features(u64 flags, u64 ro_flags);
+void btrfs_parse_features_to_string(char *buf, u64 flags, u64 ro_flags);
 
 struct btrfs_mkfs_config {
 	char *label;
@@ -115,6 +115,7 @@ struct btrfs_mkfs_config {
 	u32 sectorsize;
 	u32 stripesize;
 	u64 features;
+	u64 ro_features;
 };
 
 int make_btrfs(int fd, struct btrfs_mkfs_config *cfg);
