btrfs: add dedicated members for start and length of a block group

The on-disk format of block group item makes use of the key that stores
the offset and length. This is further used in the code, although this
makes thing harder to understand. The key is also packed so the
offset/length is not properly aligned as u64.

Add start (key.objectid) and length (key.offset) members to block group
and remove the embedded key.  When the item is searched or written, a
local variable for key is used.

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>

1 files changed, 14 insertions, 14 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index e3fd4b0ca905..b24d116eaf0b 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -75,8 +75,8 @@ void btrfs_free_excluded_extents(struct btrfs_block_group_cache *cache)
 	struct btrfs_fs_info *fs_info = cache->fs_info;
 	u64 start, end;
 
-	start = cache->key.objectid;
-	end = start + cache->key.offset - 1;
+	start = cache->start;
+	end = start + cache->length - 1;
 
 	clear_extent_bits(&fs_info->freed_extents[0],
 			  start, end, EXTENT_UPTODATE);
@@ -2560,7 +2560,7 @@ static u64 first_logical_byte(struct btrfs_fs_info *fs_info, u64 search_start)
 	if (!cache)
 		return 0;
 
-	bytenr = cache->key.objectid;
+	bytenr = cache->start;
 	btrfs_put_block_group(cache);
 
 	return bytenr;
@@ -2796,7 +2796,7 @@ static int unpin_extent_range(struct btrfs_fs_info *fs_info,
 	while (start <= end) {
 		readonly = false;
 		if (!cache ||
-		    start >= cache->key.objectid + cache->key.offset) {
+		    start >= cache->start + cache->length) {
 			if (cache)
 				btrfs_put_block_group(cache);
 			total_unpinned = 0;
@@ -2809,7 +2809,7 @@ static int unpin_extent_range(struct btrfs_fs_info *fs_info,
 			empty_cluster <<= 1;
 		}
 
-		len = cache->key.objectid + cache->key.offset - start;
+		len = cache->start + cache->length - start;
 		len = min(len, end + 1 - start);
 
 		if (start < cache->last_byte_to_unpin) {
@@ -2925,8 +2925,8 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans)
 		ret = -EROFS;
 		if (!trans->aborted)
 			ret = btrfs_discard_extent(fs_info,
-						   block_group->key.objectid,
-						   block_group->key.offset,
+						   block_group->start,
+						   block_group->length,
 						   &trimmed);
 
 		list_del_init(&block_group->bg_list);
@@ -3492,7 +3492,7 @@ static int find_free_extent_clustered(struct btrfs_block_group_cache *bg,
 		goto release_cluster;
 
 	offset = btrfs_alloc_from_cluster(cluster_bg, last_ptr,
-			ffe_ctl->num_bytes, cluster_bg->key.objectid,
+			ffe_ctl->num_bytes, cluster_bg->start,
 			&ffe_ctl->max_extent_size);
 	if (offset) {
 		/* We have a block, we're done */
@@ -3903,7 +3903,7 @@ search:
 			continue;
 
 		btrfs_grab_block_group(block_group, delalloc);
-		ffe_ctl.search_start = block_group->key.objectid;
+		ffe_ctl.search_start = block_group->start;
 
 		/*
 		 * this can happen if we end up cycling through all the
@@ -3983,7 +3983,7 @@ checks:
 
 		/* move on to the next group */
 		if (ffe_ctl.search_start + num_bytes >
-		    block_group->key.objectid + block_group->key.offset) {
+		    block_group->start + block_group->length) {
 			btrfs_add_free_space(block_group, ffe_ctl.found_offset,
 					     num_bytes);
 			goto loop;
@@ -5497,7 +5497,7 @@ u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
 		}
 
 		factor = btrfs_bg_type_to_factor(block_group->flags);
-		free_bytes += (block_group->key.offset -
+		free_bytes += (block_group->length -
 			       block_group->used) * factor;
 
 		spin_unlock(&block_group->lock);
@@ -5645,13 +5645,13 @@ int btrfs_trim_fs(struct btrfs_fs_info *fs_info, struct fstrim_range *range)
 
 	cache = btrfs_lookup_first_block_group(fs_info, range->start);
 	for (; cache; cache = btrfs_next_block_group(cache)) {
-		if (cache->key.objectid >= range_end) {
+		if (cache->start >= range_end) {
 			btrfs_put_block_group(cache);
 			break;
 		}
 
-		start = max(range->start, cache->key.objectid);
-		end = min(range_end, cache->key.objectid + cache->key.offset);
+		start = max(range->start, cache->start);
+		end = min(range_end, cache->start + cache->length);
 
 		if (end - start >= range->minlen) {
 			if (!btrfs_block_group_cache_done(cache)) {