Btrfs: Add root tree pointer transaction ids

This patch adds transaction IDs to root tree pointers.
Transaction IDs in tree pointers are compared with the
generation numbers in block headers when reading root
blocks of trees. This can detect some types of IO errors.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

fs/btrfs/ctree.h

@@ -297,6 +297,7 @@ struct btrfs_super_block {
 	__le32 leafsize;
 	__le32 stripesize;
 	__le32 sys_chunk_array_size;
+	__le64 chunk_root_generation;
 	u8 root_level;
 	u8 chunk_root_level;
 	u8 log_root_level;
@@ -448,6 +449,7 @@ struct btrfs_dir_item {
 
 struct btrfs_root_item {
 	struct btrfs_inode_item inode;
+	__le64 generation;
 	__le64 root_dirid;
 	__le64 bytenr;
 	__le64 byte_limit;
@@ -1396,10 +1398,14 @@ static inline int btrfs_is_leaf(struct extent_buffer *eb)
 }
 
 /* struct btrfs_root_item */
+BTRFS_SETGET_FUNCS(disk_root_generation, struct btrfs_root_item,
+		   generation, 64);
 BTRFS_SETGET_FUNCS(disk_root_refs, struct btrfs_root_item, refs, 32);
 BTRFS_SETGET_FUNCS(disk_root_bytenr, struct btrfs_root_item, bytenr, 64);
 BTRFS_SETGET_FUNCS(disk_root_level, struct btrfs_root_item, level, 8);
 
+BTRFS_SETGET_STACK_FUNCS(root_generation, struct btrfs_root_item,
+			 generation, 64);
 BTRFS_SETGET_STACK_FUNCS(root_bytenr, struct btrfs_root_item, bytenr, 64);
 BTRFS_SETGET_STACK_FUNCS(root_level, struct btrfs_root_item, level, 8);
 BTRFS_SETGET_STACK_FUNCS(root_dirid, struct btrfs_root_item, root_dirid, 64);
@@ -1416,6 +1422,8 @@ BTRFS_SETGET_STACK_FUNCS(super_generation, struct btrfs_super_block,
 BTRFS_SETGET_STACK_FUNCS(super_root, struct btrfs_super_block, root, 64);
 BTRFS_SETGET_STACK_FUNCS(super_sys_array_size,
 			 struct btrfs_super_block, sys_chunk_array_size, 32);
+BTRFS_SETGET_STACK_FUNCS(super_chunk_root_generation,
+			 struct btrfs_super_block, chunk_root_generation, 64);
 BTRFS_SETGET_STACK_FUNCS(super_root_level, struct btrfs_super_block,
 			 root_level, 8);
 BTRFS_SETGET_STACK_FUNCS(super_chunk_root, struct btrfs_super_block,

fs/btrfs/disk-io.c

@@ -832,6 +832,7 @@ static int find_and_setup_root(struct btrfs_root *tree_root,
 {
 	int ret;
 	u32 blocksize;
+	u64 generation;
 
 	__setup_root(tree_root->nodesize, tree_root->leafsize,
 		     tree_root->sectorsize, tree_root->stripesize,
@@ -840,9 +841,10 @@ static int find_and_setup_root(struct btrfs_root *tree_root,
 				   &root->root_item, &root->root_key);
 	BUG_ON(ret);
 
+	generation = btrfs_root_generation(&root->root_item);
 	blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
 	root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
-				     blocksize, 0);
+				     blocksize, generation);
 	BUG_ON(!root->node);
 	return 0;
 }
@@ -929,6 +931,7 @@ struct btrfs_root *btrfs_read_fs_root_no_radix(struct btrfs_root *tree_root,
 	struct btrfs_path *path;
 	struct extent_buffer *l;
 	u64 highest_inode;
+	u64 generation;
 	u32 blocksize;
 	int ret = 0;
 
@@ -970,9 +973,10 @@ out:
 		kfree(root);
 		return ERR_PTR(ret);
 	}
+	generation = btrfs_root_generation(&root->root_item);
 	blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
 	root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
-				     blocksize, 0);
+				     blocksize, generation);
 	BUG_ON(!root->node);
 insert:
 	if (location->objectid != BTRFS_TREE_LOG_OBJECTID) {
@@ -1357,6 +1361,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 	u32 leafsize;
 	u32 blocksize;
 	u32 stripesize;
+	u64 generation;
 	struct buffer_head *bh;
 	struct btrfs_root *extent_root = kzalloc(sizeof(struct btrfs_root),
 						 GFP_NOFS);
@@ -1596,13 +1601,14 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 
 	blocksize = btrfs_level_size(tree_root,
 				     btrfs_super_chunk_root_level(disk_super));
+	generation = btrfs_super_chunk_root_generation(disk_super);
 
 	__setup_root(nodesize, leafsize, sectorsize, stripesize,
 		     chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
 
 	chunk_root->node = read_tree_block(chunk_root,
 					   btrfs_super_chunk_root(disk_super),
-					   blocksize, 0);
+					   blocksize, generation);
 	BUG_ON(!chunk_root->node);
 
 	read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
@@ -1618,11 +1624,11 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 
 	blocksize = btrfs_level_size(tree_root,
 				     btrfs_super_root_level(disk_super));
-
+	generation = btrfs_super_generation(disk_super);
 
 	tree_root->node = read_tree_block(tree_root,
 					  btrfs_super_root(disk_super),
-					  blocksize, 0);
+					  blocksize, generation);
 	if (!tree_root->node)
 		goto fail_sb_buffer;
 
@@ -1672,15 +1678,16 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 			     log_tree_root, fs_info, BTRFS_TREE_LOG_OBJECTID);
 
 		log_tree_root->node = read_tree_block(tree_root, bytenr,
-						      blocksize, 0);
+						      blocksize,
+						      generation + 1);
 		ret = btrfs_recover_log_trees(log_tree_root);
 		BUG_ON(ret);
 	}
+	fs_info->last_trans_committed = btrfs_super_generation(disk_super);
 
 	ret = btrfs_cleanup_reloc_trees(tree_root);
 	BUG_ON(ret);
 
-	fs_info->last_trans_committed = btrfs_super_generation(disk_super);
 	return tree_root;
 
 fail_cleaner:

fs/btrfs/extent-tree.c

@@ -4428,6 +4428,7 @@ static int noinline init_reloc_tree(struct btrfs_trans_handle *trans,
 	btrfs_set_root_refs(root_item, 0);
 	btrfs_set_root_bytenr(root_item, eb->start);
 	btrfs_set_root_level(root_item, btrfs_header_level(eb));
+	btrfs_set_root_generation(root_item, trans->transid);
 
 	btrfs_tree_unlock(eb);
 	free_extent_buffer(eb);

fs/btrfs/ioctl.c

@@ -108,6 +108,7 @@ static noinline int create_subvol(struct btrfs_root *root,
 	inode_item->mode = cpu_to_le32(S_IFDIR | 0755);
 
 	btrfs_set_root_bytenr(&root_item, leaf->start);
+	btrfs_set_root_generation(&root_item, trans->transid);
 	btrfs_set_root_level(&root_item, 0);
 	btrfs_set_root_refs(&root_item, 1);
 	btrfs_set_root_used(&root_item, 0);

fs/btrfs/transaction.c

@@ -439,6 +439,7 @@ static int update_cowonly_root(struct btrfs_trans_handle *trans,
 				       root->node->start);
 		btrfs_set_root_level(&root->root_item,
 				     btrfs_header_level(root->node));
+		btrfs_set_root_generation(&root->root_item, trans->transid);
 		ret = btrfs_update_root(trans, tree_root,
 					&root->root_key,
 					&root->root_item);
@@ -456,6 +457,12 @@ int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	struct list_head *next;
+	struct extent_buffer *eb;
+
+	eb = btrfs_lock_root_node(fs_info->tree_root);
+	btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb, 0);
+	btrfs_tree_unlock(eb);
+	free_extent_buffer(eb);
 
 	while(!list_empty(&fs_info->dirty_cowonly_roots)) {
 		next = fs_info->dirty_cowonly_roots.next;
@@ -559,6 +566,9 @@ static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
 					      root->node->start);
 			btrfs_set_root_level(&root->root_item,
 					     btrfs_header_level(root->node));
+			btrfs_set_root_generation(&root->root_item,
+						  root->root_key.offset);
+
 			err = btrfs_insert_root(trans, root->fs_info->tree_root,
 						&root->root_key,
 						&root->root_item);
@@ -756,6 +766,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 
 	btrfs_set_root_bytenr(new_root_item, tmp->start);
 	btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
+	btrfs_set_root_generation(new_root_item, trans->transid);
 	ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
 				new_root_item);
 	btrfs_tree_unlock(tmp);
@@ -946,6 +957,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 				   chunk_root->node->start);
 	btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
 					 btrfs_header_level(chunk_root->node));
+	btrfs_set_super_chunk_root_generation(&root->fs_info->super_copy,
+				btrfs_header_generation(chunk_root->node));
 
 	if (!root->fs_info->log_root_recovering) {
 		btrfs_set_super_log_root(&root->fs_info->super_copy, 0);

fs/btrfs/tree-log.c

@@ -117,6 +117,7 @@ int btrfs_add_log_tree(struct btrfs_trans_handle *trans,
 	inode_item->mode = cpu_to_le32(S_IFDIR | 0755);
 
 	btrfs_set_root_bytenr(&root_item, leaf->start);
+	btrfs_set_root_generation(&root_item, trans->transid);
 	btrfs_set_root_level(&root_item, 0);
 	btrfs_set_root_refs(&root_item, 0);
 	btrfs_set_root_used(&root_item, 0);
@@ -2065,6 +2066,7 @@ static int update_log_root(struct btrfs_trans_handle *trans,
 		return 0;
 
 	btrfs_set_root_bytenr(&log->root_item, log->node->start);
+	btrfs_set_root_generation(&log->root_item, trans->transid);
 	btrfs_set_root_level(&log->root_item, btrfs_header_level(log->node));
 	ret = btrfs_update_root(trans, log->fs_info->log_root_tree,
 				&log->root_key, &log->root_item);