For code maintainability and scalability,
replace hardcoded constant with a meaningful enum.
Signed-off-by: Gu Jinxiang <gujx@xxxxxxxxxxxxxx>
---
mkfs/common.c | 47 ++++++++++++++++++++++++-----------------------
mkfs/common.h | 14 +++++++++++++-
2 files changed, 37 insertions(+), 24 deletions(-)
diff --git a/mkfs/common.c b/mkfs/common.c
index e4785c5..f34c4eb 100644
--- a/mkfs/common.c
+++ b/mkfs/common.c
@@ -93,18 +93,18 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
uuid_generate(super.dev_item.uuid);
uuid_generate(chunk_tree_uuid);
- cfg->blocks[0] = BTRFS_SUPER_INFO_OFFSET;
- for (i = 1; i < 7; i++) {
+ cfg->blocks[SUPER_BLOCK] = BTRFS_SUPER_INFO_OFFSET;
+ for (i = 1; i < BLOCK_COUNT; i++) {
cfg->blocks[i] = BTRFS_SUPER_INFO_OFFSET + 1024 * 1024 +
cfg->nodesize * i;
}
- btrfs_set_super_bytenr(&super, cfg->blocks[0]);
+ btrfs_set_super_bytenr(&super, cfg->blocks[SUPER_BLOCK]);
btrfs_set_super_num_devices(&super, 1);
btrfs_set_super_magic(&super, BTRFS_MAGIC_PARTIAL);
btrfs_set_super_generation(&super, 1);
- btrfs_set_super_root(&super, cfg->blocks[1]);
- btrfs_set_super_chunk_root(&super, cfg->blocks[3]);
+ btrfs_set_super_root(&super, cfg->blocks[ROOT_TREE]);
+ btrfs_set_super_chunk_root(&super, cfg->blocks[CHUNK_TREE]);
btrfs_set_super_total_bytes(&super, num_bytes);
btrfs_set_super_bytes_used(&super, 6 * cfg->nodesize);
btrfs_set_super_sectorsize(&super, cfg->sectorsize);
@@ -121,7 +121,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
/* create the tree of root objects */
memset(buf->data, 0, cfg->nodesize);
buf->len = cfg->nodesize;
- btrfs_set_header_bytenr(buf, cfg->blocks[1]);
+ btrfs_set_header_bytenr(buf, cfg->blocks[ROOT_TREE]);
btrfs_set_header_nritems(buf, 4);
btrfs_set_header_generation(buf, 1);
btrfs_set_header_backref_rev(buf, BTRFS_MIXED_BACKREF_REV);
@@ -151,7 +151,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
nritems = 0;
itemoff = __BTRFS_LEAF_DATA_SIZE(cfg->nodesize) - sizeof(root_item);
- btrfs_set_root_bytenr(&root_item, cfg->blocks[2]);
+ btrfs_set_root_bytenr(&root_item, cfg->blocks[EXTENT_TREE]);
btrfs_set_disk_key_objectid(&disk_key, BTRFS_EXTENT_TREE_OBJECTID);
btrfs_set_item_key(buf, &disk_key, nritems);
btrfs_set_item_offset(buf, btrfs_item_nr(nritems), itemoff);
@@ -162,7 +162,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
nritems++;
itemoff = itemoff - sizeof(root_item);
- btrfs_set_root_bytenr(&root_item, cfg->blocks[4]);
+ btrfs_set_root_bytenr(&root_item, cfg->blocks[DEV_TREE]);
btrfs_set_disk_key_objectid(&disk_key, BTRFS_DEV_TREE_OBJECTID);
btrfs_set_item_key(buf, &disk_key, nritems);
btrfs_set_item_offset(buf, btrfs_item_nr(nritems), itemoff);
@@ -174,7 +174,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
nritems++;
itemoff = itemoff - sizeof(root_item);
- btrfs_set_root_bytenr(&root_item, cfg->blocks[5]);
+ btrfs_set_root_bytenr(&root_item, cfg->blocks[FS_TREE]);
btrfs_set_disk_key_objectid(&disk_key, BTRFS_FS_TREE_OBJECTID);
btrfs_set_item_key(buf, &disk_key, nritems);
btrfs_set_item_offset(buf, btrfs_item_nr(nritems), itemoff);
@@ -186,7 +186,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
nritems++;
itemoff = itemoff - sizeof(root_item);
- btrfs_set_root_bytenr(&root_item, cfg->blocks[6]);
+ btrfs_set_root_bytenr(&root_item, cfg->blocks[CSUM_TREE]);
btrfs_set_disk_key_objectid(&disk_key, BTRFS_CSUM_TREE_OBJECTID);
btrfs_set_item_key(buf, &disk_key, nritems);
btrfs_set_item_offset(buf, btrfs_item_nr(nritems), itemoff);
@@ -199,7 +199,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
- ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[1]);
+ ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[ROOT_TREE]);
if (ret != cfg->nodesize) {
ret = (ret < 0 ? -errno : -EIO);
goto out;
@@ -210,7 +210,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
cfg->nodesize - sizeof(struct btrfs_header));
nritems = 0;
itemoff = __BTRFS_LEAF_DATA_SIZE(cfg->nodesize);
- for (i = 1; i < 7; i++) {
+ for (i = 1; i < BLOCK_COUNT; i++) {
item_size = sizeof(struct btrfs_extent_item);
if (!skinny_metadata)
item_size += sizeof(struct btrfs_tree_block_info);
@@ -267,11 +267,11 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
btrfs_set_item_size(buf, btrfs_item_nr(nritems), 0);
nritems++;
}
- btrfs_set_header_bytenr(buf, cfg->blocks[2]);
+ btrfs_set_header_bytenr(buf, cfg->blocks[EXTENT_TREE]);
btrfs_set_header_owner(buf, BTRFS_EXTENT_TREE_OBJECTID);
btrfs_set_header_nritems(buf, nritems);
csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
- ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[2]);
+ ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[EXTENT_TREE]);
if (ret != cfg->nodesize) {
ret = (ret < 0 ? -errno : -EIO);
goto out;
@@ -354,11 +354,11 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
ptr += item_size;
btrfs_set_super_sys_array_size(&super, array_size);
- btrfs_set_header_bytenr(buf, cfg->blocks[3]);
+ btrfs_set_header_bytenr(buf, cfg->blocks[CHUNK_TREE]);
btrfs_set_header_owner(buf, BTRFS_CHUNK_TREE_OBJECTID);
btrfs_set_header_nritems(buf, nritems);
csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
- ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[3]);
+ ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[CHUNK_TREE]);
if (ret != cfg->nodesize) {
ret = (ret < 0 ? -errno : -EIO);
goto out;
@@ -393,11 +393,11 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
BTRFS_MKFS_SYSTEM_GROUP_SIZE);
nritems++;
- btrfs_set_header_bytenr(buf, cfg->blocks[4]);
+ btrfs_set_header_bytenr(buf, cfg->blocks[DEV_TREE]);
btrfs_set_header_owner(buf, BTRFS_DEV_TREE_OBJECTID);
btrfs_set_header_nritems(buf, nritems);
csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
- ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[4]);
+ ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[DEV_TREE]);
if (ret != cfg->nodesize) {
ret = (ret < 0 ? -errno : -EIO);
goto out;
@@ -406,11 +406,11 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
/* create the FS root */
memset(buf->data + sizeof(struct btrfs_header), 0,
cfg->nodesize - sizeof(struct btrfs_header));
- btrfs_set_header_bytenr(buf, cfg->blocks[5]);
+ btrfs_set_header_bytenr(buf, cfg->blocks[FS_TREE]);
btrfs_set_header_owner(buf, BTRFS_FS_TREE_OBJECTID);
btrfs_set_header_nritems(buf, 0);
csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
- ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[5]);
+ ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[FS_TREE]);
if (ret != cfg->nodesize) {
ret = (ret < 0 ? -errno : -EIO);
goto out;
@@ -418,11 +418,11 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
/* finally create the csum root */
memset(buf->data + sizeof(struct btrfs_header), 0,
cfg->nodesize - sizeof(struct btrfs_header));
- btrfs_set_header_bytenr(buf, cfg->blocks[6]);
+ btrfs_set_header_bytenr(buf, cfg->blocks[CSUM_TREE]);
btrfs_set_header_owner(buf, BTRFS_CSUM_TREE_OBJECTID);
btrfs_set_header_nritems(buf, 0);
csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
- ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[6]);
+ ret = pwrite(fd, buf->data, cfg->nodesize, cfg->blocks[CSUM_TREE]);
if (ret != cfg->nodesize) {
ret = (ret < 0 ? -errno : -EIO);
goto out;
@@ -433,7 +433,8 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
memcpy(buf->data, &super, sizeof(super));
buf->len = BTRFS_SUPER_INFO_SIZE;
csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
- ret = pwrite(fd, buf->data, BTRFS_SUPER_INFO_SIZE, cfg->blocks[0]);
+ ret = pwrite(fd, buf->data, BTRFS_SUPER_INFO_SIZE,
+ cfg->blocks[SUPER_BLOCK]);
if (ret != BTRFS_SUPER_INFO_SIZE) {
ret = (ret < 0 ? -errno : -EIO);
goto out;
diff --git a/mkfs/common.h b/mkfs/common.h
index 666a75b..4d8a314 100644
--- a/mkfs/common.h
+++ b/mkfs/common.h
@@ -28,6 +28,18 @@
#define BTRFS_MKFS_SYSTEM_GROUP_SIZE SZ_4M
#define BTRFS_MKFS_SMALL_VOLUME_SIZE SZ_1G
+/* roots: root tree, extent tree, chunk tree, dev tree, fs tree, csum tree */
+enum btrfs_mkfs_block {
+ SUPER_BLOCK = 0,
+ ROOT_TREE,
+ EXTENT_TREE,
+ CHUNK_TREE,
+ DEV_TREE,
+ FS_TREE,
+ CSUM_TREE,
+ BLOCK_COUNT
+};
+
struct btrfs_mkfs_config {
/* Label of the new filesystem */
const char *label;
@@ -43,7 +55,7 @@ struct btrfs_mkfs_config {
/* Output fields, set during creation */
/* Logical addresses of superblock [0] and other tree roots */
- u64 blocks[8];
+ u64 blocks[BLOCK_COUNT];
char fs_uuid[BTRFS_UUID_UNPARSED_SIZE];
char chunk_uuid[BTRFS_UUID_UNPARSED_SIZE];
--
2.9.4
--
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