[PATCH] btrfs: ioctl: fix inaccurate determination of exclusive_operation

[xiaoshoukui <xiaoshoukui@gmail.com>]

with fs_info->exclusive_operation == BTRFS_EXCLOP_DEV_ADD enter
btrfs_ioctl_add_dev function , exclusive_operation will be classified
as in paused balance operation. After return from btrfs_ioctl_add_dev,
exclusive_operation will be restore to BTRFS_EXCLOP_BALANCE_PAUSED which
is not its original state.

Signed-off-by: xiaoshoukui <xiaoshoukui@ruijie.com.cn>
---
 fs/btrfs/ioctl.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a0ef1a1784c7..aab5fdb9445c 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2629,7 +2629,7 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)
 	}
 
 	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_ADD)) {
-		if (!btrfs_exclop_start_try_lock(fs_info, BTRFS_EXCLOP_DEV_ADD))
+		if (fs_info->exclusive_operation != BTRFS_EXCLOP_BALANCE_PAUSED)
 			return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
 
 		/*
@@ -2637,8 +2637,9 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)
 		 * change the exclusive op type and remember we should bring
 		 * back the paused balance
 		 */
+		spin_lock(&fs_info->super_lock);
 		fs_info->exclusive_operation = BTRFS_EXCLOP_DEV_ADD;
-		btrfs_exclop_start_unlock(fs_info);
+		spin_unlock(&fs_info->super_lock);
 		restore_op = true;
 	}
 
-- 
2.20.1