---

yaml
---
r: 332591
b: refs/heads/master
c: 354aa0f
h: refs/heads/master
i:
  332589: 1ae1f1b
  332587: 717db96
  332583: 2c220fe
  332575: 4f9474a
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a698d0755adb6f27289d1e6610b2240595d27e8c
+refs/heads/master: 354aa0fb6d5b97b262e056f7ad7bfc88d7ce0004

trunk/fs/btrfs/disk-io.c

@@ -1657,9 +1657,10 @@ static int transaction_kthread(void *arg)
 		spin_unlock(&root->fs_info->trans_lock);
 
 		/* If the file system is aborted, this will always fail. */
-		trans = btrfs_join_transaction(root);
+		trans = btrfs_attach_transaction(root);
 		if (IS_ERR(trans)) {
-			cannot_commit = true;
+			if (PTR_ERR(trans) != -ENOENT)
+				cannot_commit = true;
 			goto sleep;
 		}
 		if (transid == trans->transid) {

trunk/fs/btrfs/super.c

@@ -854,10 +854,10 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
 
 	btrfs_wait_ordered_extents(root, 0);
 
-	trans = btrfs_join_transaction_freeze(root);
+	trans = btrfs_attach_transaction(root);
 	if (IS_ERR(trans)) {
-		/* Frozen, don't bother */
-		if (PTR_ERR(trans) == -EPERM)
+		/* no transaction, don't bother */
+		if (PTR_ERR(trans) == -ENOENT)
 			return 0;
 		return PTR_ERR(trans);
 	}
@@ -1511,7 +1511,17 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 
 static int btrfs_freeze(struct super_block *sb)
 {
-	return 0;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root = btrfs_sb(sb)->tree_root;
+
+	trans = btrfs_attach_transaction(root);
+	if (IS_ERR(trans)) {
+		/* no transaction, don't bother */
+		if (PTR_ERR(trans) == -ENOENT)
+			return 0;
+		return PTR_ERR(trans);
+	}
+	return btrfs_commit_transaction(trans, root);
 }
 
 static int btrfs_unfreeze(struct super_block *sb)

trunk/fs/btrfs/transaction.c

@@ -53,7 +53,7 @@ static noinline void switch_commit_root(struct btrfs_root *root)
 /*
  * either allocate a new transaction or hop into the existing one
  */
-static noinline int join_transaction(struct btrfs_root *root, int nofail)
+static noinline int join_transaction(struct btrfs_root *root, int type)
 {
 	struct btrfs_transaction *cur_trans;
 	struct btrfs_fs_info *fs_info = root->fs_info;
@@ -67,7 +67,13 @@ static noinline int join_transaction(struct btrfs_root *root, int nofail)
 	}
 
 	if (fs_info->trans_no_join) {
-		if (!nofail) {
+		/* 
+		 * If we are JOIN_NOLOCK we're already committing a current
+		 * transaction, we just need a handle to deal with something
+		 * when committing the transaction, such as inode cache and
+		 * space cache. It is a special case.
+		 */
+		if (type != TRANS_JOIN_NOLOCK) {
 			spin_unlock(&fs_info->trans_lock);
 			return -EBUSY;
 		}
@@ -87,6 +93,13 @@ static noinline int join_transaction(struct btrfs_root *root, int nofail)
 	}
 	spin_unlock(&fs_info->trans_lock);
 
+	/*
+	 * If we are ATTACH, we just want to catch the current transaction,
+	 * and commit it. If there is no transaction, just return ENOENT.
+	 */
+	if (type == TRANS_ATTACH)
+		return -ENOENT;
+
 	cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
 	if (!cur_trans)
 		return -ENOMEM;
@@ -340,27 +353,28 @@ static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 	 * because we're already holding a ref.  We need this because we could
 	 * have raced in and did an fsync() on a file which can kick a commit
 	 * and then we deadlock with somebody doing a freeze.
+	 *
+	 * If we are ATTACH, it means we just want to catch the current
+	 * transaction and commit it, so we needn't do sb_start_intwrite(). 
 	 */
-	if (type != TRANS_JOIN_NOLOCK &&
-	    !__sb_start_write(root->fs_info->sb, SB_FREEZE_FS, false)) {
-		if (type == TRANS_JOIN_FREEZE) {
-			kmem_cache_free(btrfs_trans_handle_cachep, h);
-			return ERR_PTR(-EPERM);
-		}
+	if (type < TRANS_JOIN_NOLOCK)
 		sb_start_intwrite(root->fs_info->sb);
-	}
 
 	if (may_wait_transaction(root, type))
 		wait_current_trans(root);
 
 	do {
-		ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
+		ret = join_transaction(root, type);
 		if (ret == -EBUSY)
 			wait_current_trans(root);
 	} while (ret == -EBUSY);
 
 	if (ret < 0) {
-		sb_end_intwrite(root->fs_info->sb);
+		/* We must get the transaction if we are JOIN_NOLOCK. */
+		BUG_ON(type == TRANS_JOIN_NOLOCK);
+
+		if (type < TRANS_JOIN_NOLOCK)
+			sb_end_intwrite(root->fs_info->sb);
 		kmem_cache_free(btrfs_trans_handle_cachep, h);
 		return ERR_PTR(ret);
 	}
@@ -432,9 +446,9 @@ struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root
 	return start_transaction(root, 0, TRANS_USERSPACE, 0);
 }
 
-struct btrfs_trans_handle *btrfs_join_transaction_freeze(struct btrfs_root *root)
+struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 {
-	return start_transaction(root, 0, TRANS_JOIN_FREEZE, 0);
+	return start_transaction(root, 0, TRANS_ATTACH, 0);
 }
 
 /* wait for a transaction commit to be fully complete */
@@ -605,7 +619,7 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 		}
 	}
 
-	if (lock)
+	if (trans->type < TRANS_JOIN_NOLOCK)
 		sb_end_intwrite(root->fs_info->sb);
 
 	WARN_ON(cur_trans != info->running_transaction);
@@ -1678,7 +1692,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 	put_transaction(cur_trans);
 	put_transaction(cur_trans);
 
-	sb_end_intwrite(root->fs_info->sb);
+	if (trans->type < TRANS_JOIN_NOLOCK)
+		sb_end_intwrite(root->fs_info->sb);
 
 	trace_btrfs_transaction_commit(root);
 

trunk/fs/btrfs/transaction.h

@@ -52,7 +52,7 @@ enum btrfs_trans_type {
 	TRANS_JOIN,
 	TRANS_USERSPACE,
 	TRANS_JOIN_NOLOCK,
-	TRANS_JOIN_FREEZE,
+	TRANS_ATTACH,
 };
 
 struct btrfs_trans_handle {
@@ -109,7 +109,7 @@ struct btrfs_trans_handle *btrfs_start_transaction_noflush(
 					struct btrfs_root *root, int num_items);
 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root);
 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root);
-struct btrfs_trans_handle *btrfs_join_transaction_freeze(struct btrfs_root *root);
+struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root);
 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root);
 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid);
 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,