btrfs: remove embedded block_group_cache::item

The members ::used and ::flags are now in the block group cache
structure, the last one is chunk_objectid, but that's set to a fixed
value and otherwise unused. The item is constructed from a local
variable before write, so we can remove the embedded one from block
group.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 52e2a05..0bb1cc5 100644 (file)
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1752,8 +1752,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
                read_extent_buffer(leaf, &bgi,
                                   btrfs_item_ptr_offset(leaf, path->slots[0]),
                                   sizeof(bgi));
-               /* Duplicate as the item is still partially used */
-               memcpy(&cache->item, &bgi, sizeof(bgi));
+               /* cache::chunk_objectid is unused */
                cache->used = btrfs_block_group_used(&bgi);
                cache->flags = btrfs_block_group_flags(&bgi);
                if (!mixed &&
@@ -1879,12 +1878,9 @@ void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans)
                        goto next;
 
                spin_lock(&block_group->lock);
-               /*
-                * Copy partially filled item from the cache and ovewrite used
-                * that has the correct value
-                */
-               memcpy(&item, &block_group->item, sizeof(item));
                btrfs_set_block_group_used(&item, block_group->used);
+               btrfs_set_block_group_chunk_objectid(&item,
+                               BTRFS_FIRST_CHUNK_TREE_OBJECTID);
                btrfs_set_block_group_flags(&item, block_group->flags);
                memcpy(&key, &block_group->key, sizeof(key));
                spin_unlock(&block_group->lock);
@@ -1919,8 +1915,6 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans, u64 bytes_used,
                return -ENOMEM;
 
        cache->used = bytes_used;
-       btrfs_set_block_group_chunk_objectid(&cache->item,
-                                            BTRFS_FIRST_CHUNK_TREE_OBJECTID);
        cache->flags = type;
        cache->last_byte_to_unpin = (u64)-1;
        cache->cached = BTRFS_CACHE_FINISHED;
@@ -2136,9 +2130,9 @@ static int write_one_cache_group(struct btrfs_trans_handle *trans,
 
        leaf = path->nodes[0];
        bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
-       /* Partial copy of item, update the rest from memory */
-       memcpy(&bgi, &cache->item, sizeof(bgi));
        btrfs_set_block_group_used(&bgi, cache->used);
+       btrfs_set_block_group_chunk_objectid(&bgi,
+                       BTRFS_FIRST_CHUNK_TREE_OBJECTID);
        btrfs_set_block_group_flags(&bgi, cache->flags);
        write_extent_buffer(leaf, &bgi, bi, sizeof(bgi));
        btrfs_mark_buffer_dirty(leaf);

diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
index 8fa4a70..d78fce7 100644 (file)
--- a/fs/btrfs/block-group.h
+++ b/fs/btrfs/block-group.h
@@ -44,7 +44,6 @@ struct btrfs_caching_control {
 
 struct btrfs_block_group_cache {
        struct btrfs_key key;
-       struct btrfs_block_group_item item;
        struct btrfs_fs_info *fs_info;
        struct inode *inode;
        spinlock_t lock;