Btrfs-progs: add support for mixed data+metadata block groups

So alot of crazy people (I'm looking at you Meego) want to use btrfs on phones
and such with small devices.  Unfortunately the way we split out metadata/data
chunks it makes space usage inefficient for volumes that are smaller than
1gigabyte.  So add a -M option for mixing metadata+data, and default to this
mixed mode if the filesystem is less than or equal to 1 gigabyte.  I've tested
this with xfstests on a 100mb filesystem and everything is a-ok.

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 87 insertions, 35 deletions

diff --git a/mkfs.c b/mkfs.c
index 2e99b952..04de93aa 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -69,7 +69,7 @@ static u64 parse_size(char *s)
 	return atol(s) * mult;
 }
 
-static int make_root_dir(struct btrfs_root *root)
+static int make_root_dir(struct btrfs_root *root, int mixed)
 {
 	struct btrfs_trans_handle *trans;
 	struct btrfs_key location;
@@ -88,30 +88,47 @@ static int make_root_dir(struct btrfs_root *root)
 				     0, BTRFS_MKFS_SYSTEM_GROUP_SIZE);
 	BUG_ON(ret);
 
-	ret = btrfs_alloc_chunk(trans, root->fs_info->extent_root,
-				&chunk_start, &chunk_size,
-				BTRFS_BLOCK_GROUP_METADATA);
-	BUG_ON(ret);
-	ret = btrfs_make_block_group(trans, root, 0,
-				     BTRFS_BLOCK_GROUP_METADATA,
-				     BTRFS_FIRST_CHUNK_TREE_OBJECTID,
-				     chunk_start, chunk_size);
-	BUG_ON(ret);
+	if (mixed) {
+		ret = btrfs_alloc_chunk(trans, root->fs_info->extent_root,
+					&chunk_start, &chunk_size,
+					BTRFS_BLOCK_GROUP_METADATA |
+					BTRFS_BLOCK_GROUP_DATA);
+		BUG_ON(ret);
+		ret = btrfs_make_block_group(trans, root, 0,
+					     BTRFS_BLOCK_GROUP_METADATA |
+					     BTRFS_BLOCK_GROUP_DATA,
+					     BTRFS_FIRST_CHUNK_TREE_OBJECTID,
+					     chunk_start, chunk_size);
+		BUG_ON(ret);
+		printf("Created a data/metadata chunk of size %llu\n", chunk_size);
+	} else {
+		ret = btrfs_alloc_chunk(trans, root->fs_info->extent_root,
+					&chunk_start, &chunk_size,
+					BTRFS_BLOCK_GROUP_METADATA);
+		BUG_ON(ret);
+		ret = btrfs_make_block_group(trans, root, 0,
+					     BTRFS_BLOCK_GROUP_METADATA,
+					     BTRFS_FIRST_CHUNK_TREE_OBJECTID,
+					     chunk_start, chunk_size);
+		BUG_ON(ret);
+	}
 
 	root->fs_info->system_allocs = 0;
 	btrfs_commit_transaction(trans, root);
 	trans = btrfs_start_transaction(root, 1);
 	BUG_ON(!trans);
 
-	ret = btrfs_alloc_chunk(trans, root->fs_info->extent_root,
-				&chunk_start, &chunk_size,
-				BTRFS_BLOCK_GROUP_DATA);
-	BUG_ON(ret);
-	ret = btrfs_make_block_group(trans, root, 0,
-				     BTRFS_BLOCK_GROUP_DATA,
-				     BTRFS_FIRST_CHUNK_TREE_OBJECTID,
-				     chunk_start, chunk_size);
-	BUG_ON(ret);
+	if (!mixed) {
+		ret = btrfs_alloc_chunk(trans, root->fs_info->extent_root,
+					&chunk_start, &chunk_size,
+					BTRFS_BLOCK_GROUP_DATA);
+		BUG_ON(ret);
+		ret = btrfs_make_block_group(trans, root, 0,
+					     BTRFS_BLOCK_GROUP_DATA,
+					     BTRFS_FIRST_CHUNK_TREE_OBJECTID,
+					     chunk_start, chunk_size);
+		BUG_ON(ret);
+	}
 
 	ret = btrfs_make_root_dir(trans, root->fs_info->tree_root,
 			      BTRFS_ROOT_TREE_DIR_OBJECTID);
@@ -200,7 +217,7 @@ static int create_one_raid_group(struct btrfs_trans_handle *trans,
 
 static int create_raid_groups(struct btrfs_trans_handle *trans,
 			      struct btrfs_root *root, u64 data_profile,
-			      u64 metadata_profile)
+			      u64 metadata_profile, int mixed)
 {
 	u64 num_devices = btrfs_super_num_devices(&root->fs_info->super_copy);
 	u64 allowed;
@@ -215,20 +232,24 @@ static int create_raid_groups(struct btrfs_trans_handle *trans,
 		allowed = BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1;
 
 	if (allowed & metadata_profile) {
+		u64 meta_flags = BTRFS_BLOCK_GROUP_METADATA;
+
 		ret = create_one_raid_group(trans, root,
 					    BTRFS_BLOCK_GROUP_SYSTEM |
 					    (allowed & metadata_profile));
 		BUG_ON(ret);
 
-		ret = create_one_raid_group(trans, root,
-					    BTRFS_BLOCK_GROUP_METADATA |
+		if (mixed)
+			meta_flags |= BTRFS_BLOCK_GROUP_DATA;
+
+		ret = create_one_raid_group(trans, root, meta_flags |
 					    (allowed & metadata_profile));
 		BUG_ON(ret);
 
 		ret = recow_roots(trans, root);
 		BUG_ON(ret);
 	}
-	if (num_devices > 1 && (allowed & data_profile)) {
+	if (!mixed && num_devices > 1 && (allowed & data_profile)) {
 		ret = create_one_raid_group(trans, root,
 					    BTRFS_BLOCK_GROUP_DATA |
 					    (allowed & data_profile));
@@ -274,6 +295,7 @@ static void print_usage(void)
 	fprintf(stderr, "\t -l --leafsize size of btree leaves\n");
 	fprintf(stderr, "\t -L --label set a label\n");
 	fprintf(stderr, "\t -m --metadata metadata profile, values like data profile\n");
+	fprintf(stderr, "\t -M --mixed mix metadata and data together\n");
 	fprintf(stderr, "\t -n --nodesize size of btree nodes\n");
 	fprintf(stderr, "\t -s --sectorsize min block allocation\n");
 	fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
@@ -328,6 +350,7 @@ static struct option long_options[] = {
 	{ "leafsize", 1, NULL, 'l' },
 	{ "label", 1, NULL, 'L'},
 	{ "metadata", 1, NULL, 'm' },
+	{ "mixed", 0, NULL, 'M' },
 	{ "nodesize", 1, NULL, 'n' },
 	{ "sectorsize", 1, NULL, 's' },
 	{ "data", 1, NULL, 'd' },
@@ -358,10 +381,13 @@ int main(int ac, char **av)
 	int first_fd;
 	int ret;
 	int i;
+	int mixed = 0;
+	int data_profile_opt = 0;
+	int metadata_profile_opt = 0;
 
 	while(1) {
 		int c;
-		c = getopt_long(ac, av, "A:b:l:n:s:m:d:L:V", long_options,
+		c = getopt_long(ac, av, "A:b:l:n:s:m:d:L:VM", long_options,
 				&option_index);
 		if (c < 0)
 			break;
@@ -371,6 +397,7 @@ int main(int ac, char **av)
 				break;
 			case 'd':
 				data_profile = parse_profile(optarg);
+				data_profile_opt = 1;
 				break;
 			case 'l':
 				leafsize = parse_size(optarg);
@@ -380,6 +407,10 @@ int main(int ac, char **av)
 				break;
 			case 'm':
 				metadata_profile = parse_profile(optarg);
+				metadata_profile_opt = 1;
+				break;
+			case 'M':
+				mixed = 1;
 				break;
 			case 'n':
 				nodesize = parse_size(optarg);
@@ -389,12 +420,10 @@ int main(int ac, char **av)
 				break;
 			case 'b':
 				block_count = parse_size(optarg);
-				if (block_count < 256*1024*1024) {
-					fprintf(stderr, "File system size "
-						"%llu bytes is too small, "
-						"256M is required at least\n",
-						(unsigned long long)block_count);
-					exit(1);
+				if (block_count <= 1024*1024*1024) {
+					printf("SMALL VOLUME: forcing mixed "
+					       "metadata/data groups\n");
+					mixed = 1;
 				}
 				zero_end = 0;
 				break;
@@ -439,9 +468,22 @@ int main(int ac, char **av)
 	}
 	first_fd = fd;
 	first_file = file;
-	ret = btrfs_prepare_device(fd, file, zero_end, &dev_block_count);
+	ret = btrfs_prepare_device(fd, file, zero_end, &dev_block_count,
+				   &mixed);
 	if (block_count == 0)
 		block_count = dev_block_count;
+	if (mixed) {
+		if (!metadata_profile_opt)
+			metadata_profile = 0;
+		if (!data_profile_opt)
+			data_profile = 0;
+
+		if (metadata_profile != data_profile) {
+			fprintf(stderr, "With mixed block groups data and metadata "
+				"profiles must be the same\n");
+			exit(1);
+		}
+	}
 
 	blocks[0] = BTRFS_SUPER_INFO_OFFSET;
 	for (i = 1; i < 7; i++) {
@@ -459,7 +501,7 @@ int main(int ac, char **av)
 	root = open_ctree(file, 0, O_RDWR);
 	root->fs_info->alloc_start = alloc_start;
 
-	ret = make_root_dir(root);
+	ret = make_root_dir(root, mixed);
 	if (ret) {
 		fprintf(stderr, "failed to setup the root directory\n");
 		exit(1);
@@ -478,6 +520,8 @@ int main(int ac, char **av)
 
 	zero_end = 1;
 	while(ac-- > 0) {
+		int old_mixed = mixed;
+
 		file = av[optind++];
 		ret = check_mounted(file);
 		if (ret < 0) {
@@ -503,8 +547,8 @@ int main(int ac, char **av)
 			continue;
 		}
 		ret = btrfs_prepare_device(fd, file, zero_end,
-					   &dev_block_count);
-
+					   &dev_block_count, &mixed);
+		mixed = old_mixed;
 		BUG_ON(ret);
 
 		ret = btrfs_add_to_fsid(trans, root, fd, file, dev_block_count,
@@ -515,12 +559,20 @@ int main(int ac, char **av)
 
 raid_groups:
 	ret = create_raid_groups(trans, root, data_profile,
-				 metadata_profile);
+				 metadata_profile, mixed);
 	BUG_ON(ret);
 
 	ret = create_data_reloc_tree(trans, root);
 	BUG_ON(ret);
 
+	if (mixed) {
+		struct btrfs_super_block *super = &root->fs_info->super_copy;
+		u64 flags = btrfs_super_incompat_flags(super);
+
+		flags |= BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS;
+		btrfs_set_super_incompat_flags(super, flags);
+	}
+
 	printf("fs created label %s on %s\n\tnodesize %u leafsize %u "
 	    "sectorsize %u size %s\n",
 	    label, first_file, nodesize, leafsize, sectorsize,