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btrfs: factor out reading of bg from find_frist_block_group 

When find_first_block_group() finds a block group item in the extent-tree,
it does a lookup of the object in the extent mapping tree and does further
checks on the item.

Factor out this step from find_first_block_group() so we can further
simplify the code.

While we're at it, we can also just return early in
find_first_block_group(), if the tree slot isn't found.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Johannes Thumshirn 2020-06-02 19:05:57 +09:00 committed by David Sterba
parent 89d7da9bc5
commit e3ba67a108
1 changed files with 56 additions and 46 deletions
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102
fs/btrfs/block-group.c
View File

@ -1532,21 +1532,70 @@ void btrfs_mark_bg_unused(struct btrfs_block_group *bg)
spin_unlock(&fs_info->unused_bgs_lock);
}
static int read_bg_from_eb(struct btrfs_fs_info *fs_info, struct btrfs_key *key,
struct btrfs_path *path)
{
struct extent_map_tree *em_tree;
struct extent_map *em;
struct btrfs_block_group_item bg;
struct extent_buffer *leaf;
int slot;
u64 flags;
int ret = 0;
slot = path->slots[0];
leaf = path->nodes[0];
em_tree = &fs_info->mapping_tree;
read_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, key->objectid, key->offset);
read_unlock(&em_tree->lock);
if (!em) {
btrfs_err(fs_info,
"logical %llu len %llu found bg but no related chunk",
key->objectid, key->offset);
return -ENOENT;
}
if (em->start != key->objectid || em->len != key->offset) {
btrfs_err(fs_info,
"block group %llu len %llu mismatch with chunk %llu len %llu",
key->objectid, key->offset, em->start, em->len);
ret = -EUCLEAN;
goto out_free_em;
}
read_extent_buffer(leaf, &bg, btrfs_item_ptr_offset(leaf, slot),
sizeof(bg));
flags = btrfs_stack_block_group_flags(&bg) &
BTRFS_BLOCK_GROUP_TYPE_MASK;
if (flags != (em->map_lookup->type & BTRFS_BLOCK_GROUP_TYPE_MASK)) {
btrfs_err(fs_info,
"block group %llu len %llu type flags 0x%llx mismatch with chunk type flags 0x%llx",
key->objectid, key->offset, flags,
(BTRFS_BLOCK_GROUP_TYPE_MASK & em->map_lookup->type));
ret = -EUCLEAN;
}
out_free_em:
free_extent_map(em);
return ret;
}
static int find_first_block_group(struct btrfs_fs_info *fs_info,
struct btrfs_path *path,
struct btrfs_key *key)
{
struct btrfs_root *root = fs_info->extent_root;
int ret = 0;
int ret;
struct btrfs_key found_key;
struct extent_buffer *leaf;
struct btrfs_block_group_item bg;
u64 flags;
int slot;
ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
if (ret < 0)
goto out;
return ret;
while (1) {
slot = path->slots[0];
@ -1563,49 +1612,10 @@ static int find_first_block_group(struct btrfs_fs_info *fs_info,
if (found_key.objectid >= key->objectid &&
found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
struct extent_map_tree *em_tree;
struct extent_map *em;
em_tree = &fs_info->mapping_tree;
read_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, found_key.objectid,
found_key.offset);
read_unlock(&em_tree->lock);
if (!em) {
btrfs_err(fs_info,
"logical %llu len %llu found bg but no related chunk",
found_key.objectid, found_key.offset);
ret = -ENOENT;
} else if (em->start != found_key.objectid ||
em->len != found_key.offset) {
btrfs_err(fs_info,
"block group %llu len %llu mismatch with chunk %llu len %llu",
found_key.objectid, found_key.offset,
em->start, em->len);
ret = -EUCLEAN;
} else {
read_extent_buffer(leaf, &bg,
btrfs_item_ptr_offset(leaf, slot),
sizeof(bg));
flags = btrfs_stack_block_group_flags(&bg) &
BTRFS_BLOCK_GROUP_TYPE_MASK;
if (flags != (em->map_lookup->type &
BTRFS_BLOCK_GROUP_TYPE_MASK)) {
btrfs_err(fs_info,
"block group %llu len %llu type flags 0x%llx mismatch with chunk type flags 0x%llx",
found_key.objectid,
found_key.offset, flags,
(BTRFS_BLOCK_GROUP_TYPE_MASK &
em->map_lookup->type));
ret = -EUCLEAN;
} else {
ret = 0;
}
}
free_extent_map(em);
goto out;
ret = read_bg_from_eb(fs_info, &found_key, path);
break;
}
path->slots[0]++;
}
out: