Btrfs: groundwork for subvolume and snapshot roots

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 103 insertions, 37 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 20d84bd03223..83a0194ab163 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -8,6 +8,8 @@ static int total_trans = 0;
 extern struct kmem_cache *btrfs_trans_handle_cachep;
 extern struct kmem_cache *btrfs_transaction_cachep;
 
+#define BTRFS_ROOT_TRANS_TAG 0
+
 #define TRANS_MAGIC 0xE1E10E
 static void put_transaction(struct btrfs_transaction *transaction)
 {
@@ -31,9 +33,10 @@ static int join_transaction(struct btrfs_root *root)
 					     GFP_NOFS);
 		total_trans++;
 		BUG_ON(!cur_trans);
+		root->fs_info->generation++;
 		root->fs_info->running_transaction = cur_trans;
 		cur_trans->num_writers = 0;
-		cur_trans->transid = root->root_key.offset + 1;
+		cur_trans->transid = root->fs_info->generation;
 		init_waitqueue_head(&cur_trans->writer_wait);
 		init_waitqueue_head(&cur_trans->commit_wait);
 		cur_trans->magic = TRANS_MAGIC;
@@ -51,13 +54,22 @@ struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 	struct btrfs_trans_handle *h =
 		kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 	int ret;
+	u64 running_trans_id;
 
-	/* FIXME, use the right root */
-	root = root->fs_info->fs_root;
 	mutex_lock(&root->fs_info->trans_mutex);
 	ret = join_transaction(root);
 	BUG_ON(ret);
-	h->transid = root->fs_info->running_transaction->transid;
+	running_trans_id = root->fs_info->running_transaction->transid;
+
+	if (root != root->fs_info->tree_root && root->last_trans <
+	    running_trans_id) {
+		radix_tree_tag_set(&root->fs_info->fs_roots_radix,
+				   (unsigned long)root, BTRFS_ROOT_TRANS_TAG);
+		root->commit_root = root->node;
+		get_bh(root->node);
+	}
+	root->last_trans = running_trans_id;
+	h->transid = running_trans_id;
 	h->transaction = root->fs_info->running_transaction;
 	h->blocks_reserved = num_blocks;
 	h->blocks_used = 0;
@@ -72,9 +84,6 @@ int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_transaction *cur_trans;
 
-	/* FIXME, use the right root */
-	root = root->fs_info->fs_root;
-
 	WARN_ON(trans->magic != TRANS_MAGIC);
 	WARN_ON(trans->magic2 != TRANS_MAGIC);
 	mutex_lock(&root->fs_info->trans_mutex);
@@ -145,17 +154,96 @@ static int wait_for_commit(struct btrfs_root *root,
 	return 0;
 }
 
+struct dirty_root {
+	struct list_head list;
+	struct btrfs_key snap_key;
+	struct buffer_head *commit_root;
+	struct btrfs_root *root;
+};
+
+int add_dirty_roots(struct btrfs_trans_handle *trans,
+		    struct radix_tree_root *radix, struct list_head *list)
+{
+	struct dirty_root *dirty;
+	struct btrfs_root *gang[8];
+	struct btrfs_root *root;
+	int i;
+	int ret;
+	int err;
+printk("add dirty\n");
+	while(1) {
+		ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
+						 ARRAY_SIZE(gang),
+						 BTRFS_ROOT_TRANS_TAG);
+		if (ret == 0)
+			break;
+		for (i = 0; i < ret; i++) {
+			root = gang[i];
+			radix_tree_tag_clear(radix, (unsigned long)root,
+					     BTRFS_ROOT_TRANS_TAG);
+			if (root->commit_root == root->node) {
+				WARN_ON(root->node->b_blocknr !=
+					btrfs_root_blocknr(&root->root_item));
+				brelse(root->commit_root);
+				root->commit_root = NULL;
+				continue;
+			}
+			dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
+			BUG_ON(!dirty);
+			memcpy(&dirty->snap_key, &root->root_key,
+			       sizeof(root->root_key));
+			dirty->commit_root = root->commit_root;
+			root->commit_root = NULL;
+			dirty->root = root;
+printk("adding dirty root %Lu gen %Lu blocknr %Lu\n", root->root_key.objectid, root->root_key.offset, dirty->commit_root->b_blocknr);
+			root->root_key.offset = root->fs_info->generation;
+			btrfs_set_root_blocknr(&root->root_item,
+					       root->node->b_blocknr);
+			err = btrfs_insert_root(trans, root->fs_info->tree_root,
+						&root->root_key,
+						&root->root_item);
+			BUG_ON(err);
+			list_add(&dirty->list, list);
+		}
+	}
+printk("add dirty done\n");
+	return 0;
+}
+
+int drop_dirty_roots(struct btrfs_root *tree_root, struct list_head *list)
+{
+	struct dirty_root *dirty;
+	struct btrfs_trans_handle *trans;
+	int ret;
+
+	while(!list_empty(list)) {
+		dirty = list_entry(list->next, struct dirty_root, list);
+		list_del_init(&dirty->list);
+		trans = btrfs_start_transaction(tree_root, 1);
+printk("drop snapshot root %p, commit_root blocknr %Lu generation %Lu\n", dirty->root, dirty->commit_root->b_blocknr, dirty->snap_key.offset);
+		ret = btrfs_drop_snapshot(trans, dirty->root,
+					  dirty->commit_root);
+		BUG_ON(ret);
+
+printk("del root objectid %Lu, offset %Lu\n", dirty->snap_key.objectid, dirty->snap_key.offset);
+		ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
+		BUG_ON(ret);
+		ret = btrfs_end_transaction(trans, tree_root);
+		BUG_ON(ret);
+		kfree(dirty);
+	}
+	return 0;
+}
+
 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 			     struct btrfs_root *root)
 {
 	int ret = 0;
-	struct buffer_head *snap;
-	struct btrfs_key snap_key;
 	struct btrfs_transaction *cur_trans;
+	struct list_head dirty_fs_roots;
 	DEFINE_WAIT(wait);
 
-	/* FIXME, use the right root */
-	root = root->fs_info->fs_root;
+	INIT_LIST_HEAD(&dirty_fs_roots);
 
 	mutex_lock(&root->fs_info->trans_mutex);
 	if (trans->transaction->in_commit) {
@@ -184,22 +272,13 @@ printk("already in commit!, waiting\n");
 	}
 	finish_wait(&trans->transaction->writer_wait, &wait);
 	WARN_ON(cur_trans != trans->transaction);
-	if (root->node != root->commit_root) {
-		memcpy(&snap_key, &root->root_key, sizeof(snap_key));
-		root->root_key.offset++;
-	}
-
-	if (btrfs_root_blocknr(&root->root_item) != root->node->b_blocknr) {
-		btrfs_set_root_blocknr(&root->root_item, root->node->b_blocknr);
-		ret = btrfs_insert_root(trans, root->fs_info->tree_root,
-					&root->root_key, &root->root_item);
-		BUG_ON(ret);
-	}
-
+	add_dirty_roots(trans, &root->fs_info->fs_roots_radix, &dirty_fs_roots);
 	ret = btrfs_commit_tree_roots(trans, root);
 	BUG_ON(ret);
 	cur_trans = root->fs_info->running_transaction;
 	root->fs_info->running_transaction = NULL;
+	btrfs_set_super_generation(root->fs_info->disk_super,
+				   root->fs_info->generation + 1);
 	mutex_unlock(&root->fs_info->trans_mutex);
 	ret = btrfs_write_and_wait_transaction(trans, root);
 	BUG_ON(ret);
@@ -213,21 +292,8 @@ printk("already in commit!, waiting\n");
 	put_transaction(cur_trans);
 	mutex_unlock(&root->fs_info->trans_mutex);
 	kmem_cache_free(btrfs_trans_handle_cachep, trans);
-	if (root->node != root->commit_root) {
-		trans = btrfs_start_transaction(root, 1);
-		snap = root->commit_root;
-		root->commit_root = root->node;
-		get_bh(root->node);
-		ret = btrfs_drop_snapshot(trans, root, snap);
-		BUG_ON(ret);
 
-		ret = btrfs_del_root(trans, root->fs_info->tree_root,
-				     &snap_key);
-		BUG_ON(ret);
-		root->fs_info->generation = root->root_key.offset + 1;
-		ret = btrfs_end_transaction(trans, root);
-		BUG_ON(ret);
-	}
+	drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 	return ret;
 }