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btrfs-progs: Refactor btrfs_read_block_groups() 

This patch does the following refactor:
- Refactor parameter from @root to @fs_info

- Refactor the large loop body into another function
  Now we have a helper function, read_one_block_group(), to handle
  block group cache and space info related routine.

- Refactor the return value
  Even we have the code handling ret > 0 from find_first_block_group(),
  it never works, as when there is no more block group,
  find_first_block_group() just return -ENOENT other than 1.

  This is super confusing, it's almost a mircle it even works.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
master
Qu Wenruo 2019-10-10 14:41:51 +08:00 committed by David Sterba
parent e46281d6fb
commit e33a73b754
3 changed files with 96 additions and 74 deletions
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2
ctree.h
View File

@ -2545,7 +2545,7 @@ int update_space_info(struct btrfs_fs_info *info, u64 flags,
u64 total_bytes, u64 bytes_used,
struct btrfs_space_info **space_info);
int btrfs_free_block_groups(struct btrfs_fs_info *info);
int btrfs_read_block_groups(struct btrfs_root *root);
int btrfs_read_block_groups(struct btrfs_fs_info *info);
struct btrfs_block_group_cache *
btrfs_add_block_group(struct btrfs_fs_info *fs_info, u64 bytes_used, u64 type,
u64 chunk_offset, u64 size);

9
disk-io.c
View File

@ -998,14 +998,17 @@ int btrfs_setup_all_roots(struct btrfs_fs_info *fs_info, u64 root_tree_bytenr,
fs_info->last_trans_committed = generation;
if (extent_buffer_uptodate(fs_info->extent_root->node) &&
!(flags & OPEN_CTREE_NO_BLOCK_GROUPS)) {
ret = btrfs_read_block_groups(fs_info->tree_root);
ret = btrfs_read_block_groups(fs_info);
/*
* If we don't find any blockgroups (ENOENT) we're either
* restoring or creating the filesystem, where it's expected,
* anything else is error
*/
if (ret != -ENOENT)
return -EIO;
if (ret < 0 && ret != -ENOENT) {
errno = -ret;
error("failed to read block groups: %m");
return ret;
}
}
key.objectid = BTRFS_FS_TREE_OBJECTID;

159
extent-tree.c
View File

@ -2607,6 +2607,13 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
return 0;
}
/*
* Find a block group which starts >= @key->objectid in extent tree.
*
* Return 0 for found
* Retrun >0 for not found
* Return <0 for error
*/
static int find_first_block_group(struct btrfs_root *root,
struct btrfs_path *path, struct btrfs_key *key)
{
@ -2636,36 +2643,93 @@ static int find_first_block_group(struct btrfs_root *root,
return 0;
path->slots[0]++;
}
ret = -ENOENT;
ret = 1;
error:
return ret;
}
int btrfs_read_block_groups(struct btrfs_root *root)
/*
* Read out one BLOCK_GROUP_ITEM and insert it into block group cache.
*
* Return 0 if nothing wrong (either insert the bg cache or skip 0 sized bg)
* Return <0 for error.
*/
static int read_one_block_group(struct btrfs_fs_info *fs_info,
struct btrfs_path *path)
{
struct btrfs_path *path;
int ret;
int bit;
struct btrfs_block_group_cache *cache;
struct btrfs_fs_info *info = root->fs_info;
struct extent_io_tree *block_group_cache = &fs_info->block_group_cache;
struct extent_buffer *leaf = path->nodes[0];
struct btrfs_space_info *space_info;
struct extent_io_tree *block_group_cache;
struct btrfs_block_group_cache *cache;
struct btrfs_key key;
struct btrfs_key found_key;
struct extent_buffer *leaf;
int slot = path->slots[0];
int bit = 0;
int ret;
block_group_cache = &info->block_group_cache;
btrfs_item_key_to_cpu(leaf, &key, slot);
ASSERT(key.type == BTRFS_BLOCK_GROUP_ITEM_KEY);
root = info->extent_root;
/*
* Skip 0 sized block group, don't insert them into block group cache
* tree, as its length is 0, it won't get freed at close_ctree() time.
*/
if (key.offset == 0)
return 0;
cache = kzalloc(sizeof(*cache), GFP_NOFS);
if (!cache)
return -ENOMEM;
read_extent_buffer(leaf, &cache->item,
btrfs_item_ptr_offset(leaf, slot),
sizeof(cache->item));
memcpy(&cache->key, &key, sizeof(key));
cache->cached = 0;
cache->pinned = 0;
cache->flags = btrfs_block_group_flags(&cache->item);
if (cache->flags & BTRFS_BLOCK_GROUP_DATA) {
bit = BLOCK_GROUP_DATA;
} else if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
bit = BLOCK_GROUP_SYSTEM;
} else if (cache->flags & BTRFS_BLOCK_GROUP_METADATA) {
bit = BLOCK_GROUP_METADATA;
}
set_avail_alloc_bits(fs_info, cache->flags);
if (btrfs_chunk_readonly(fs_info, cache->key.objectid))
cache->ro = 1;
exclude_super_stripes(fs_info, cache);
ret = update_space_info(fs_info, cache->flags, cache->key.offset,
btrfs_block_group_used(&cache->item),
&space_info);
if (ret < 0) {
free(cache);
return ret;
}
cache->space_info = space_info;
set_extent_bits(block_group_cache, cache->key.objectid,
cache->key.objectid + cache->key.offset - 1,
bit | EXTENT_LOCKED);
set_state_private(block_group_cache, cache->key.objectid,
(unsigned long)cache);
return 0;
}
int btrfs_read_block_groups(struct btrfs_fs_info *fs_info)
{
struct btrfs_path path;
struct btrfs_root *root;
int ret;
struct btrfs_key key;
root = fs_info->extent_root;
key.objectid = 0;
key.offset = 0;
key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
btrfs_init_path(&path);
while(1) {
ret = find_first_block_group(root, path, &key);
ret = find_first_block_group(root, &path, &key);
if (ret > 0) {
ret = 0;
goto error;
@ -2673,67 +2737,22 @@ int btrfs_read_block_groups(struct btrfs_root *root)
if (ret != 0) {
goto error;
}
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
cache = kzalloc(sizeof(*cache), GFP_NOFS);
if (!cache) {
ret = -ENOMEM;
ret = read_one_block_group(fs_info, &path);
if (ret < 0)
goto error;
}
read_extent_buffer(leaf, &cache->item,
btrfs_item_ptr_offset(leaf, path->slots[0]),
sizeof(cache->item));
memcpy(&cache->key, &found_key, sizeof(found_key));
cache->cached = 0;
cache->pinned = 0;
key.objectid = found_key.objectid + found_key.offset;
if (found_key.offset == 0)
if (key.offset == 0)
key.objectid++;
btrfs_release_path(path);
/*
* Skip 0 sized block group, don't insert them into block
* group cache tree, as its length is 0, it won't get
* freed at close_ctree() time.
*/
if (found_key.offset == 0) {
free(cache);
continue;
}
cache->flags = btrfs_block_group_flags(&cache->item);
bit = 0;
if (cache->flags & BTRFS_BLOCK_GROUP_DATA) {
bit = BLOCK_GROUP_DATA;
} else if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
bit = BLOCK_GROUP_SYSTEM;
} else if (cache->flags & BTRFS_BLOCK_GROUP_METADATA) {
bit = BLOCK_GROUP_METADATA;
}
set_avail_alloc_bits(info, cache->flags);
if (btrfs_chunk_readonly(info, cache->key.objectid))
cache->ro = 1;
exclude_super_stripes(info, cache);
ret = update_space_info(info, cache->flags, found_key.offset,
btrfs_block_group_used(&cache->item),
&space_info);
BUG_ON(ret);
cache->space_info = space_info;
/* use EXTENT_LOCKED to prevent merging */
set_extent_bits(block_group_cache, found_key.objectid,
found_key.objectid + found_key.offset - 1,
bit | EXTENT_LOCKED);
set_state_private(block_group_cache, found_key.objectid,
(unsigned long)cache);
else
key.objectid = key.objectid + key.offset;
key.offset = 0;
btrfs_release_path(&path);
}
ret = 0;
error:
btrfs_free_path(path);
btrfs_release_path(&path);
return ret;
}