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, 41 insertions, 42 deletions

diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c
index 48a03f5240f5..d3aa65a4c76f 100644
--- a/fs/btrfs/free-space-tree.c
+++ b/fs/btrfs/free-space-tree.c
@@ -27,8 +27,7 @@ void set_free_space_tree_thresholds(struct btrfs_block_group_cache *cache)
 	 * exceeds that required for using bitmaps.
 	 */
 	bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
-	num_bitmaps = div_u64(cache->key.offset + bitmap_range - 1,
-			      bitmap_range);
+	num_bitmaps = div_u64(cache->length + bitmap_range - 1, bitmap_range);
 	bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
 	total_bitmap_size = num_bitmaps * bitmap_size;
 	cache->bitmap_high_thresh = div_u64(total_bitmap_size,
@@ -54,9 +53,9 @@ static int add_new_free_space_info(struct btrfs_trans_handle *trans,
 	struct extent_buffer *leaf;
 	int ret;
 
-	key.objectid = block_group->key.objectid;
+	key.objectid = block_group->start;
 	key.type = BTRFS_FREE_SPACE_INFO_KEY;
-	key.offset = block_group->key.offset;
+	key.offset = block_group->length;
 
 	ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
 	if (ret)
@@ -86,16 +85,16 @@ struct btrfs_free_space_info *search_free_space_info(
 	struct btrfs_key key;
 	int ret;
 
-	key.objectid = block_group->key.objectid;
+	key.objectid = block_group->start;
 	key.type = BTRFS_FREE_SPACE_INFO_KEY;
-	key.offset = block_group->key.offset;
+	key.offset = block_group->length;
 
 	ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
 	if (ret < 0)
 		return ERR_PTR(ret);
 	if (ret != 0) {
 		btrfs_warn(fs_info, "missing free space info for %llu",
-			   block_group->key.objectid);
+			   block_group->start);
 		ASSERT(0);
 		return ERR_PTR(-ENOENT);
 	}
@@ -197,7 +196,7 @@ int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
 	int done = 0, nr;
 	int ret;
 
-	bitmap_size = free_space_bitmap_size(block_group->key.offset,
+	bitmap_size = free_space_bitmap_size(block_group->length,
 					     fs_info->sectorsize);
 	bitmap = alloc_bitmap(bitmap_size);
 	if (!bitmap) {
@@ -205,8 +204,8 @@ int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
 		goto out;
 	}
 
-	start = block_group->key.objectid;
-	end = block_group->key.objectid + block_group->key.offset;
+	start = block_group->start;
+	end = block_group->start + block_group->length;
 
 	key.objectid = end - 1;
 	key.type = (u8)-1;
@@ -224,8 +223,8 @@ int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
 			btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
 
 			if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
-				ASSERT(found_key.objectid == block_group->key.objectid);
-				ASSERT(found_key.offset == block_group->key.offset);
+				ASSERT(found_key.objectid == block_group->start);
+				ASSERT(found_key.offset == block_group->length);
 				done = 1;
 				break;
 			} else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
@@ -271,7 +270,7 @@ int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
 	if (extent_count != expected_extent_count) {
 		btrfs_err(fs_info,
 			  "incorrect extent count for %llu; counted %u, expected %u",
-			  block_group->key.objectid, extent_count,
+			  block_group->start, extent_count,
 			  expected_extent_count);
 		ASSERT(0);
 		ret = -EIO;
@@ -336,7 +335,7 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
 	int done = 0, nr;
 	int ret;
 
-	bitmap_size = free_space_bitmap_size(block_group->key.offset,
+	bitmap_size = free_space_bitmap_size(block_group->length,
 					     fs_info->sectorsize);
 	bitmap = alloc_bitmap(bitmap_size);
 	if (!bitmap) {
@@ -344,8 +343,8 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
 		goto out;
 	}
 
-	start = block_group->key.objectid;
-	end = block_group->key.objectid + block_group->key.offset;
+	start = block_group->start;
+	end = block_group->start + block_group->length;
 
 	key.objectid = end - 1;
 	key.type = (u8)-1;
@@ -363,8 +362,8 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
 			btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
 
 			if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
-				ASSERT(found_key.objectid == block_group->key.objectid);
-				ASSERT(found_key.offset == block_group->key.offset);
+				ASSERT(found_key.objectid == block_group->start);
+				ASSERT(found_key.offset == block_group->length);
 				done = 1;
 				break;
 			} else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
@@ -413,7 +412,7 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
 	btrfs_mark_buffer_dirty(leaf);
 	btrfs_release_path(path);
 
-	nrbits = div_u64(block_group->key.offset, block_group->fs_info->sectorsize);
+	nrbits = div_u64(block_group->length, block_group->fs_info->sectorsize);
 	start_bit = find_next_bit_le(bitmap, nrbits, 0);
 
 	while (start_bit < nrbits) {
@@ -437,7 +436,7 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
 	if (extent_count != expected_extent_count) {
 		btrfs_err(fs_info,
 			  "incorrect extent count for %llu; counted %u, expected %u",
-			  block_group->key.objectid, extent_count,
+			  block_group->start, extent_count,
 			  expected_extent_count);
 		ASSERT(0);
 		ret = -EIO;
@@ -597,7 +596,7 @@ static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
 	 * Read the bit for the block immediately before the extent of space if
 	 * that block is within the block group.
 	 */
-	if (start > block_group->key.objectid) {
+	if (start > block_group->start) {
 		u64 prev_block = start - block_group->fs_info->sectorsize;
 
 		key.objectid = prev_block;
@@ -649,7 +648,7 @@ static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
 	 * Read the bit for the block immediately after the extent of space if
 	 * that block is within the block group.
 	 */
-	if (end < block_group->key.objectid + block_group->key.offset) {
+	if (end < block_group->start + block_group->length) {
 		/* The next block may be in the next bitmap. */
 		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 		if (end >= key.objectid + key.offset) {
@@ -880,7 +879,7 @@ static int add_free_space_extent(struct btrfs_trans_handle *trans,
 	new_key.offset = size;
 
 	/* Search for a neighbor on the left. */
-	if (start == block_group->key.objectid)
+	if (start == block_group->start)
 		goto right;
 	key.objectid = start - 1;
 	key.type = (u8)-1;
@@ -900,8 +899,8 @@ static int add_free_space_extent(struct btrfs_trans_handle *trans,
 
 	found_start = key.objectid;
 	found_end = key.objectid + key.offset;
-	ASSERT(found_start >= block_group->key.objectid &&
-	       found_end > block_group->key.objectid);
+	ASSERT(found_start >= block_group->start &&
+	       found_end > block_group->start);
 	ASSERT(found_start < start && found_end <= start);
 
 	/*
@@ -920,7 +919,7 @@ static int add_free_space_extent(struct btrfs_trans_handle *trans,
 
 right:
 	/* Search for a neighbor on the right. */
-	if (end == block_group->key.objectid + block_group->key.offset)
+	if (end == block_group->start + block_group->length)
 		goto insert;
 	key.objectid = end;
 	key.type = (u8)-1;
@@ -940,8 +939,8 @@ right:
 
 	found_start = key.objectid;
 	found_end = key.objectid + key.offset;
-	ASSERT(found_start >= block_group->key.objectid &&
-	       found_end > block_group->key.objectid);
+	ASSERT(found_start >= block_group->start &&
+	       found_end > block_group->start);
 	ASSERT((found_start < start && found_end <= start) ||
 	       (found_start >= end && found_end > end));
 
@@ -1075,7 +1074,7 @@ static int populate_free_space_tree(struct btrfs_trans_handle *trans,
 	 * BLOCK_GROUP_ITEM, so an extent may precede the block group that it's
 	 * contained in.
 	 */
-	key.objectid = block_group->key.objectid;
+	key.objectid = block_group->start;
 	key.type = BTRFS_EXTENT_ITEM_KEY;
 	key.offset = 0;
 
@@ -1084,8 +1083,8 @@ static int populate_free_space_tree(struct btrfs_trans_handle *trans,
 		goto out_locked;
 	ASSERT(ret == 0);
 
-	start = block_group->key.objectid;
-	end = block_group->key.objectid + block_group->key.offset;
+	start = block_group->start;
+	end = block_group->start + block_group->length;
 	while (1) {
 		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 
@@ -1109,7 +1108,7 @@ static int populate_free_space_tree(struct btrfs_trans_handle *trans,
 			else
 				start += key.offset;
 		} else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
-			if (key.objectid != block_group->key.objectid)
+			if (key.objectid != block_group->start)
 				break;
 		}
 
@@ -1277,8 +1276,8 @@ static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
 		return ret;
 
 	return __add_to_free_space_tree(trans, block_group, path,
-					block_group->key.objectid,
-					block_group->key.offset);
+					block_group->start,
+					block_group->length);
 }
 
 int add_block_group_free_space(struct btrfs_trans_handle *trans,
@@ -1336,8 +1335,8 @@ int remove_block_group_free_space(struct btrfs_trans_handle *trans,
 		goto out;
 	}
 
-	start = block_group->key.objectid;
-	end = block_group->key.objectid + block_group->key.offset;
+	start = block_group->start;
+	end = block_group->start + block_group->length;
 
 	key.objectid = end - 1;
 	key.type = (u8)-1;
@@ -1355,8 +1354,8 @@ int remove_block_group_free_space(struct btrfs_trans_handle *trans,
 			btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
 
 			if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
-				ASSERT(found_key.objectid == block_group->key.objectid);
-				ASSERT(found_key.offset == block_group->key.offset);
+				ASSERT(found_key.objectid == block_group->start);
+				ASSERT(found_key.offset == block_group->length);
 				done = 1;
 				nr++;
 				path->slots[0]--;
@@ -1407,7 +1406,7 @@ static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
 	fs_info = block_group->fs_info;
 	root = fs_info->free_space_root;
 
-	end = block_group->key.objectid + block_group->key.offset;
+	end = block_group->start + block_group->length;
 
 	while (1) {
 		ret = btrfs_next_item(root, path);
@@ -1454,7 +1453,7 @@ static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
 	if (extent_count != expected_extent_count) {
 		btrfs_err(fs_info,
 			  "incorrect extent count for %llu; counted %u, expected %u",
-			  block_group->key.objectid, extent_count,
+			  block_group->start, extent_count,
 			  expected_extent_count);
 		ASSERT(0);
 		ret = -EIO;
@@ -1485,7 +1484,7 @@ static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
 	fs_info = block_group->fs_info;
 	root = fs_info->free_space_root;
 
-	end = block_group->key.objectid + block_group->key.offset;
+	end = block_group->start + block_group->length;
 
 	while (1) {
 		ret = btrfs_next_item(root, path);
@@ -1516,7 +1515,7 @@ static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
 	if (extent_count != expected_extent_count) {
 		btrfs_err(fs_info,
 			  "incorrect extent count for %llu; counted %u, expected %u",
-			  block_group->key.objectid, extent_count,
+			  block_group->start, extent_count,
 			  expected_extent_count);
 		ASSERT(0);
 		ret = -EIO;