1 files changed, 54 insertions, 17 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index edfecfe62b4b..a5bd6926f7ff 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -387,6 +387,7 @@ bool btrfs_exclop_start(struct btrfs_fs_info *fs_info,
  *
  * Compatibility:
  * - the same type is already running
+ * - when trying to add a device and balance has been paused
  * - not BTRFS_EXCLOP_NONE - this is intentionally incompatible and the caller
  *   must check the condition first that would allow none -> @type
  */
@@ -394,7 +395,9 @@ bool btrfs_exclop_start_try_lock(struct btrfs_fs_info *fs_info,
 				 enum btrfs_exclusive_operation type)
 {
 	spin_lock(&fs_info->super_lock);
-	if (fs_info->exclusive_operation == type)
+	if (fs_info->exclusive_operation == type ||
+	    (fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED &&
+	     type == BTRFS_EXCLOP_DEV_ADD))
 		return true;
 
 	spin_unlock(&fs_info->super_lock);
@@ -414,6 +417,29 @@ void btrfs_exclop_finish(struct btrfs_fs_info *fs_info)
 	sysfs_notify(&fs_info->fs_devices->fsid_kobj, NULL, "exclusive_operation");
 }
 
+void btrfs_exclop_balance(struct btrfs_fs_info *fs_info,
+			  enum btrfs_exclusive_operation op)
+{
+	switch (op) {
+	case BTRFS_EXCLOP_BALANCE_PAUSED:
+		spin_lock(&fs_info->super_lock);
+		ASSERT(fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE ||
+		       fs_info->exclusive_operation == BTRFS_EXCLOP_DEV_ADD);
+		fs_info->exclusive_operation = BTRFS_EXCLOP_BALANCE_PAUSED;
+		spin_unlock(&fs_info->super_lock);
+		break;
+	case BTRFS_EXCLOP_BALANCE:
+		spin_lock(&fs_info->super_lock);
+		ASSERT(fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED);
+		fs_info->exclusive_operation = BTRFS_EXCLOP_BALANCE;
+		spin_unlock(&fs_info->super_lock);
+		break;
+	default:
+		btrfs_warn(fs_info,
+			"invalid exclop balance operation %d requested", op);
+	}
+}
+
 static int btrfs_ioctl_getversion(struct file *file, int __user *arg)
 {
 	struct inode *inode = file_inode(file);
@@ -518,7 +544,6 @@ static noinline int create_subvol(struct user_namespace *mnt_userns,
 	struct timespec64 cur_time = current_time(dir);
 	struct inode *inode;
 	int ret;
-	int err;
 	dev_t anon_dev = 0;
 	u64 objectid;
 	u64 index = 0;
@@ -698,9 +723,10 @@ fail:
 	trans->bytes_reserved = 0;
 	btrfs_subvolume_release_metadata(root, &block_rsv);
 
-	err = btrfs_commit_transaction(trans);
-	if (err && !ret)
-		ret = err;
+	if (ret)
+		btrfs_end_transaction(trans);
+	else
+		ret = btrfs_commit_transaction(trans);
 
 	if (!ret) {
 		inode = btrfs_lookup_dentry(dir, dentry);
@@ -2084,7 +2110,7 @@ static noinline int copy_to_sk(struct btrfs_path *path,
 
 	for (i = slot; i < nritems; i++) {
 		item_off = btrfs_item_ptr_offset(leaf, i);
-		item_len = btrfs_item_size_nr(leaf, i);
+		item_len = btrfs_item_size(leaf, i);
 
 		btrfs_item_key_to_cpu(leaf, key, i);
 		if (!key_in_sk(key, sk))
@@ -2538,7 +2564,7 @@ static int btrfs_search_path_in_tree_user(struct user_namespace *mnt_userns,
 	btrfs_item_key_to_cpu(leaf, &key, slot);
 
 	item_off = btrfs_item_ptr_offset(leaf, slot);
-	item_len = btrfs_item_size_nr(leaf, slot);
+	item_len = btrfs_item_size(leaf, slot);
 	/* Check if dirid in ROOT_REF corresponds to passed dirid */
 	rref = btrfs_item_ptr(leaf, slot, struct btrfs_root_ref);
 	if (args->dirid != btrfs_root_ref_dirid(leaf, rref)) {
@@ -2740,7 +2766,7 @@ static int btrfs_ioctl_get_subvol_info(struct file *file, void __user *argp)
 
 			item_off = btrfs_item_ptr_offset(leaf, slot)
 					+ sizeof(struct btrfs_root_ref);
-			item_len = btrfs_item_size_nr(leaf, slot)
+			item_len = btrfs_item_size(leaf, slot)
 					- sizeof(struct btrfs_root_ref);
 			read_extent_buffer(leaf, subvol_info->name,
 					   item_off, item_len);
@@ -3148,13 +3174,25 @@ out:
 static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)
 {
 	struct btrfs_ioctl_vol_args *vol_args;
+	bool restore_op = false;
 	int ret;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_ADD))
-		return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
+	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_ADD)) {
+		if (!btrfs_exclop_start_try_lock(fs_info, BTRFS_EXCLOP_DEV_ADD))
+			return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
+
+		/*
+		 * We can do the device add because we have a paused balanced,
+		 * change the exclusive op type and remember we should bring
+		 * back the paused balance
+		 */
+		fs_info->exclusive_operation = BTRFS_EXCLOP_DEV_ADD;
+		btrfs_exclop_start_unlock(fs_info);
+		restore_op = true;
+	}
 
 	vol_args = memdup_user(arg, sizeof(*vol_args));
 	if (IS_ERR(vol_args)) {
@@ -3170,7 +3208,10 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)
 
 	kfree(vol_args);
 out:
-	btrfs_exclop_finish(fs_info);
+	if (restore_op)
+		btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE_PAUSED);
+	else
+		btrfs_exclop_finish(fs_info);
 	return ret;
 }
 
@@ -3622,7 +3663,6 @@ static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
 {
 	struct btrfs_trans_handle *trans;
 	u64 transid;
-	int ret;
 
 	trans = btrfs_attach_transaction_barrier(root);
 	if (IS_ERR(trans)) {
@@ -3634,11 +3674,7 @@ static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
 		goto out;
 	}
 	transid = trans->transid;
-	ret = btrfs_commit_transaction_async(trans);
-	if (ret) {
-		btrfs_end_transaction(trans);
-		return ret;
-	}
+	btrfs_commit_transaction_async(trans);
 out:
 	if (argp)
 		if (copy_to_user(argp, &transid, sizeof(transid)))
@@ -4061,6 +4097,7 @@ locked:
 			spin_lock(&fs_info->balance_lock);
 			bctl->flags |= BTRFS_BALANCE_RESUME;
 			spin_unlock(&fs_info->balance_lock);
+			btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE);
 
 			goto do_balance;
 		}