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>

4 files changed, 33 insertions, 4 deletions

diff --git a/ctree.h b/ctree.h
index 9b16275b..ede36540 100644
--- a/ctree.h
+++ b/ctree.h
@@ -279,6 +279,7 @@ 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;
@@ -421,6 +422,7 @@ struct btrfs_dir_item {
 
 struct btrfs_root_item {
 	struct btrfs_inode_item inode;
+	__le64 generation;
 	__le64 root_dirid;
 	__le64 bytenr;
 	__le64 byte_limit;
@@ -1234,10 +1236,14 @@ 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);
@@ -1253,6 +1259,8 @@ 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,
diff --git a/disk-io.c b/disk-io.c
index f2cbd4af..06815728 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -274,6 +274,8 @@ static int update_cowonly_root(struct btrfs_trans_handle *trans,
 			break;
 		btrfs_set_root_bytenr(&root->root_item,
 				       root->node->start);
+		btrfs_set_root_generation(&root->root_item,
+					  trans->transid);
 		root->root_item.level = btrfs_header_level(root->node);
 		ret = btrfs_update_root(trans, tree_root,
 					&root->root_key,
@@ -289,6 +291,12 @@ static int commit_tree_roots(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_root *root;
 	struct list_head *next;
+	struct extent_buffer *eb;
+
+	eb = fs_info->tree_root->node;
+	extent_buffer_get(eb);
+	btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
+	free_extent_buffer(eb);
 
 	while(!list_empty(&fs_info->dirty_cowonly_roots)) {
 		next = fs_info->dirty_cowonly_roots.next;
@@ -345,6 +353,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
 	root->root_key.offset = trans->transid;
 	btrfs_set_root_bytenr(&root->root_item, root->node->start);
+	btrfs_set_root_generation(&root->root_item, root->root_key.offset);
 	root->root_item.level = btrfs_header_level(root->node);
 	ret = btrfs_insert_root(trans, fs_info->tree_root,
 				&root->root_key, &root->root_item);
@@ -395,6 +404,7 @@ 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,
@@ -404,8 +414,9 @@ static int find_and_setup_root(struct btrfs_root *tree_root,
 	BUG_ON(ret);
 
 	blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
+	generation = btrfs_root_generation(&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;
 }
@@ -428,6 +439,7 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
 	struct btrfs_root *tree_root = fs_info->tree_root;
 	struct btrfs_path *path;
 	struct extent_buffer *l;
+	u64 generation;
 	u32 blocksize;
 	int ret = 0;
 
@@ -470,9 +482,10 @@ out:
 		free(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:
 	root->ref_cows = 1;
@@ -506,6 +519,7 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
 	u32 leafsize;
 	u32 blocksize;
 	u32 stripesize;
+	u64 generation;
 	struct btrfs_root *root = malloc(sizeof(struct btrfs_root));
 	struct btrfs_root *tree_root = malloc(sizeof(struct btrfs_root));
 	struct btrfs_root *extent_root = malloc(sizeof(struct btrfs_root));
@@ -604,13 +618,14 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
 	BUG_ON(ret);
 	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);
 
@@ -623,10 +638,11 @@ struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
 
 	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);
 	BUG_ON(!tree_root->node);
 	ret = find_and_setup_root(tree_root, fs_info,
 				  BTRFS_EXTENT_TREE_OBJECTID, extent_root);
@@ -706,6 +722,8 @@ int write_ctree_super(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));
 	write_extent_buffer(root->fs_info->sb_buffer,
 			    &root->fs_info->super_copy, 0,
 			    sizeof(root->fs_info->super_copy));
diff --git a/mkfs.c b/mkfs.c
index 3c09c3a9..dae43e97 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -247,6 +247,7 @@ static int create_data_reloc_tree(struct btrfs_trans_handle *trans,
 	memcpy(&root_item, &root->root_item, sizeof(root_item));
 	btrfs_set_root_bytenr(&root_item, tmp->start);
 	btrfs_set_root_level(&root_item, btrfs_header_level(tmp));
+	btrfs_set_root_generation(&root_item, trans->transid);
 	free_extent_buffer(tmp);
 
 	location.objectid = objectid;
diff --git a/utils.c b/utils.c
index 6b76dd3c..fa3cef46 100644
--- a/utils.c
+++ b/utils.c
@@ -101,6 +101,7 @@ int make_btrfs(int fd, const char *device, const char *label,
 	btrfs_set_super_leafsize(&super, leafsize);
 	btrfs_set_super_nodesize(&super, nodesize);
 	btrfs_set_super_stripesize(&super, stripesize);
+	btrfs_set_super_chunk_root_generation(&super, 1);
 	if (label)
 		strcpy(super.label, label);
 
@@ -130,6 +131,7 @@ int make_btrfs(int fd, const char *device, const char *label,
 	btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
 	btrfs_set_root_refs(&root_item, 1);
 	btrfs_set_root_used(&root_item, leafsize);
+	btrfs_set_root_generation(&root_item, 1);
 
 	memset(&disk_key, 0, sizeof(disk_key));
 	btrfs_set_disk_key_type(&disk_key, BTRFS_ROOT_ITEM_KEY);