[PATCH v2 3/7] btrfs-progs: Enable read-write ability for 'bg_tree' feature

Qu Wenruo
2019-10-08T04:49:48Z

Allow btrfs-progs to open, read and write 'bg_tree' enabled fs.

The modification itself is not large, as block groups items are only
used at 4 timing:
1) open_ctree()
We only need to populate fs_info->bg_root and read block group items
from fs_info->bg_root.
The obvious change is, we don't need to do btrfs_search_slot() for
each block group item, but btrfs_next_item() is enough.

This should hugely reduce open_ctree() execution duration.

2) btrfs_commit_transaction()
We need to write back dirty block group items back to bg_root.

The modification here is to insert new block group item if we can't
find one existing in bg_root, and delete the old one in extent tree
if we're converting to bg_tree feature.

3) btrfs_make_block_group()
Just change @root for btrfs_insert_item() from @extent_root to
@bg_root for fs with that feature.

This modification needs extra handling for converting case, where
block group items can be either in extent tree or bg tree.

4) free_block_group_item()
Just delete the block group item in extent tree.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
ctree.h | 11 +++-
disk-io.c | 20 +++++++
extent-tree.c | 152 +++++++++++++++++++++++++++++++++++++++++++++-----
3 files changed, 168 insertions(+), 15 deletions(-)

diff --git a/ctree.h b/ctree.h
index 2899de358613..c2a18c8ab72f 100644
--- a/ctree.h
+++ b/ctree.h
@@ -89,6 +89,9 @@ struct btrfs_free_space_ctl;
/* tracks free space in block groups. */
#define BTRFS_FREE_SPACE_TREE_OBJECTID 10ULL

+/* store BLOCK_GROUP_ITEMS in a seperate tree */
+#define BTRFS_BLOCK_GROUP_TREE_OBJECTID 11ULL
+
/* device stats in the device tree */
#define BTRFS_DEV_STATS_OBJECTID 0ULL

@@ -490,6 +493,7 @@ struct btrfs_super_block {
#define BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA (1ULL << 8)
#define BTRFS_FEATURE_INCOMPAT_NO_HOLES (1ULL << 9)
#define BTRFS_FEATURE_INCOMPAT_METADATA_UUID (1ULL << 10)
+#define BTRFS_FEATURE_INCOMPAT_BG_TREE (1ULL << 11)

#define BTRFS_FEATURE_COMPAT_SUPP 0ULL

@@ -513,7 +517,8 @@ struct btrfs_super_block {
BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS | \
BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA | \
BTRFS_FEATURE_INCOMPAT_NO_HOLES | \
- BTRFS_FEATURE_INCOMPAT_METADATA_UUID)
+ BTRFS_FEATURE_INCOMPAT_METADATA_UUID | \
+ BTRFS_FEATURE_INCOMPAT_BG_TREE)

/*
* A leaf is full of items. offset and size tell us where to find
@@ -1123,6 +1128,7 @@ struct btrfs_fs_info {
struct btrfs_root *quota_root;
struct btrfs_root *free_space_root;
struct btrfs_root *uuid_root;
+ struct btrfs_root *bg_root;

struct rb_root fs_root_tree;

@@ -1175,6 +1181,9 @@ struct btrfs_fs_info {
unsigned int avoid_sys_chunk_alloc:1;
unsigned int finalize_on_close:1;

+ /* Converting from bg in extent tree to bg tree */
+ unsigned int convert_to_bg_tree:1;
+
int transaction_aborted;

int (*free_extent_hook)(struct btrfs_fs_info *fs_info,
diff --git a/disk-io.c b/disk-io.c
index 8978f0cb60c7..38248aa895b8 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -716,6 +716,8 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
if (location->objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
return fs_info->free_space_root ? fs_info->free_space_root :
ERR_PTR(-ENOENT);
+ if (location->objectid == BTRFS_BLOCK_GROUP_TREE_OBJECTID)
+ return fs_info->bg_root ? fs_info->bg_root : ERR_PTR(-ENOENT);

BUG_ON(location->objectid == BTRFS_TREE_RELOC_OBJECTID ||
location->offset != (u64)-1);
@@ -768,6 +770,7 @@ struct btrfs_fs_info *btrfs_new_fs_info(int writable, u64 sb_bytenr)
fs_info->quota_root = calloc(1, sizeof(struct btrfs_root));
fs_info->free_space_root = calloc(1, sizeof(struct btrfs_root));
fs_info->uuid_root = calloc(1, sizeof(struct btrfs_root));
+ fs_info->bg_root = calloc(1, sizeof(struct btrfs_root));
fs_info->super_copy = calloc(1, BTRFS_SUPER_INFO_SIZE);

if (!fs_info->tree_root || !fs_info->extent_root ||
@@ -930,6 +933,21 @@ int btrfs_setup_all_roots(struct btrfs_fs_info *fs_info, u64 root_tree_bytenr,
return ret;
fs_info->extent_root->track_dirty = 1;

+ if (btrfs_fs_incompat(fs_info, BG_TREE)) {
+ ret = setup_root_or_create_block(fs_info, flags,
+ fs_info->bg_root,
+ BTRFS_BLOCK_GROUP_TREE_OBJECTID, "bg");
+ if (ret < 0) {
+ error("Couldn't setup bg tree");
+ return ret;
+ }
+ fs_info->bg_root->track_dirty = 1;
+ fs_info->bg_root->ref_cows = 0;
+ } else {
+ free(fs_info->bg_root);
+ fs_info->bg_root = NULL;
+ }
+
ret = find_and_setup_root(root, fs_info, BTRFS_DEV_TREE_OBJECTID,
fs_info->dev_root);
if (ret) {
@@ -1012,6 +1030,8 @@ void btrfs_release_all_roots(struct btrfs_fs_info *fs_info)
free_extent_buffer(fs_info->free_space_root->node);
if (fs_info->quota_root)
free_extent_buffer(fs_info->quota_root->node);
+ if (fs_info->bg_root)
+ free_extent_buffer(fs_info->bg_root->node);
if (fs_info->csum_root)
free_extent_buffer(fs_info->csum_root->node);
if (fs_info->dev_root)
diff --git a/extent-tree.c b/extent-tree.c
index 9713d627764c..cb3d7a1add0f 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -1528,22 +1528,68 @@ static int write_one_cache_group(struct btrfs_trans_handle *trans,
struct btrfs_path *path,
struct btrfs_block_group_cache *cache)
{
+ bool is_bg_tree = btrfs_fs_incompat(trans->fs_info, BG_TREE);
int ret;
- struct btrfs_root *extent_root = trans->fs_info->extent_root;
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ struct btrfs_root *root;
unsigned long bi;
struct extent_buffer *leaf;

- ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
+ if (is_bg_tree)
+ root = fs_info->bg_root;
+ else
+ root = fs_info->extent_root;
+
+ ret = btrfs_search_slot(trans, root, &cache->key, path, 0, 1);
if (ret < 0)
- goto fail;
- BUG_ON(ret);
+ goto out;

- leaf = path->nodes[0];
- bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
- write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
- btrfs_mark_buffer_dirty(leaf);
- btrfs_release_path(path);
-fail:
+ if (ret == 0) {
+ /* Update existing bg */
+ leaf = path->nodes[0];
+ bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
+ write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
+ btrfs_mark_buffer_dirty(leaf);
+ btrfs_release_path(path);
+ } else {
+ btrfs_release_path(path);
+
+ /*
+ * Insert new bg item
+ *
+ * This only happens for bg_tree feature
+ */
+ if (!is_bg_tree) {
+ error("can't find block group item for bytenr %llu",
+ cache->key.objectid);
+ ret = -ENOENT;
+ goto out;
+ }
+ ret = btrfs_insert_item(trans, root, &cache->key, &cache->item,
+ sizeof(cache->item));
+ if (ret < 0)
+ goto out;
+
+ /* Also delete the existing one in next tree if needed */
+ if (fs_info->convert_to_bg_tree) {
+ ret = btrfs_search_slot(trans, fs_info->extent_root,
+ &cache->key, path, -1, 1);
+ if (ret < 0) {
+ btrfs_release_path(path);
+ goto out;
+ }
+ /* Good, already converted */
+ if (ret > 0) {
+ ret = 0;
+ btrfs_release_path(path);
+ goto out;
+ }
+ /* Delete old block group item in extent tree */
+ ret = btrfs_del_item(trans, fs_info->extent_root, path);
+ btrfs_release_path(path);
+ }
+ }
+out:
if (ret)
return ret;
return 0;
@@ -2717,14 +2763,66 @@ static int read_one_block_group(struct btrfs_fs_info *fs_info,
return 0;
}

+static int read_block_group_tree(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_root *root = fs_info->bg_root;
+ struct btrfs_key key = { 0 };
+ struct btrfs_path path;
+ int ret;
+
+ btrfs_init_path(&path);
+ ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+ if (ret < 0) {
+ errno = -ret;
+ error("failed to search block group tree: %m");
+ return ret;
+ }
+ if (ret == 0)
+ goto invalid_key;
+
+ while (1) {
+ btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
+ if (key.type != BTRFS_BLOCK_GROUP_ITEM_KEY)
+ goto invalid_key;
+
+ ret = read_one_block_group(fs_info, &path);
+ if (ret < 0) {
+ errno = -ret;
+ error("failed to read one block group: %m");
+ goto out;
+ }
+ ret = btrfs_next_item(root, &path);
+ if (ret < 0) {
+ errno = -ret;
+ error("failed to search block group tree: %m");
+ goto out;
+ }
+ if (ret > 0) {
+ ret = 0;
+ break;
+ }
+ }
+out:
+ btrfs_release_path(&path);
+ return ret;
+
+invalid_key:
+ error("invalid key (%llu, %u, %llu) found in block group tree",
+ key.objectid, key.type, key.offset);
+ btrfs_release_path(&path);
+ return -EUCLEAN;
+}
+
int btrfs_read_block_groups(struct btrfs_fs_info *fs_info)
{
struct btrfs_path path;
- struct btrfs_root *root;
+ struct btrfs_root *root = fs_info->extent_root;
int ret;
struct btrfs_key key;

- root = fs_info->extent_root;
+ if (btrfs_fs_incompat(fs_info, BG_TREE))
+ return read_block_group_tree(fs_info);
+
key.objectid = 0;
key.offset = 0;
key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
@@ -2804,12 +2902,17 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
u64 type, u64 chunk_offset, u64 size)
{
int ret;
- struct btrfs_root *extent_root = fs_info->extent_root;
+ struct btrfs_root *root;
struct btrfs_block_group_cache *cache;

+ if (btrfs_fs_incompat(fs_info, BG_TREE))
+ root = fs_info->bg_root;
+ else
+ root = fs_info->extent_root;
+
cache = btrfs_add_block_group(fs_info, bytes_used, type, chunk_offset,
size);
- ret = btrfs_insert_item(trans, extent_root, &cache->key, &cache->item,
+ ret = btrfs_insert_item(trans, root, &cache->key, &cache->item,
sizeof(cache->item));
BUG_ON(ret);

@@ -2943,8 +3046,16 @@ static int free_block_group_item(struct btrfs_trans_handle *trans,
if (!path)
return -ENOMEM;

+ /* Using bg tree only */
+ if (btrfs_fs_incompat(fs_info, BG_TREE) && !fs_info->convert_to_bg_tree)
+ goto bg_tree;
+
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret > 0) {
+ if (btrfs_fs_incompat(fs_info, BG_TREE)) {
+ btrfs_release_path(path);
+ goto bg_tree;
+ }
ret = -ENOENT;
goto out;
}
@@ -2952,6 +3063,19 @@ static int free_block_group_item(struct btrfs_trans_handle *trans,
goto out;

ret = btrfs_del_item(trans, root, path);
+ goto out;
+
+bg_tree:
+ root = fs_info->bg_root;
+ ret = btrfs_search_slot(trans, fs_info->bg_root, &key, path, -1, 1);
+ if (ret < 0)
+ goto out;
+ if (ret > 0) {
+ ret = -ENOENT;
+ goto out;
+ }
+ ret = btrfs_del_item(trans, root, path);
+
out:
btrfs_free_path(path);
return ret;
--
2.23.0