Re: [PATCH 3/5] Btrfs: pause/recover the space balance when doing remount

pause the space balance threads when remounting the fs to be readonly,
and recover it when remounting it from r/o to r/w

Signed-off-by: Miao Xie <redacted>
---
 fs/btrfs/super.c   |    9 ++++++++-
 fs/btrfs/volumes.c |    8 +++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 7deb00e..ea17f0a 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c

@@ -1148,6 +1148,9 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 	if (*flags & MS_RDONLY) {
 		sb->s_flags |= MS_RDONLY;
 
+		/* pause restriper - we want to resume on remount to r/w */
+		btrfs_pause_balance(root->fs_info);
+
 		ret = btrfs_commit_super(root);
 		if (ret)
 			goto restore;

@@ -1174,7 +1177,10 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 		if (ret)
 			goto restore;
 
-		sb->s_flags &= ~MS_RDONLY;
+		if (sb->s_flags & MS_RDONLY) {
+			sb->s_flags &= ~MS_RDONLY;
+			btrfs_recover_balance(fs_info->tree_root);
+		}
 	}
 
 	return 0;

@@ -1190,6 +1196,7 @@ restore:
 	fs_info->alloc_start = old_alloc_start;
 	fs_info->thread_pool_size = old_thread_pool_size;
 	fs_info->metadata_ratio = old_metadata_ratio;
+
 	return ret;
 }
 

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 91da8a2..c536d52 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c

@@ -2833,7 +2833,13 @@ static int balance_kthread(void *data)
 	mutex_lock(&fs_info->volume_mutex);
 	mutex_lock(&fs_info->balance_mutex);
 
-	set_balance_control(bctl);
+	if (fs_info->balance_ctl) {
+		kfree(bctl);
+		bctl = fs_info->balance_ctl;
+		bctl->flags = bctl->flags | BTRFS_BALANCE_RESUME;
+	} else {
+		set_balance_control(bctl);
+	}
 
 	if (btrfs_test_opt(fs_info->tree_root, SKIP_BALANCE)) {
 		printk(KERN_INFO "btrfs: force skipping balance\n");