btrfs: track running balance in a simpler way
Currently fs_info::balance_running is 0 or 1 and does not use the
semantics of atomics. The pause and cancel check for 0, that can happen
only after __btrfs_balance exits for whatever reason.
Parallel calls to balance ioctl may enter btrfs_ioctl_balance multiple
times but will block on the balance_mutex that protects the
fs_info::flags bit.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index c690092..ffb224b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4312,7 +4312,7 @@ void update_ioctl_balance_args(struct btrfs_fs_info *fs_info, int lock,
bargs->flags = bctl->flags;
- if (atomic_read(&fs_info->balance_running))
+ if (test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags))
bargs->state |= BTRFS_BALANCE_STATE_RUNNING;
if (atomic_read(&fs_info->balance_pause_req))
bargs->state |= BTRFS_BALANCE_STATE_PAUSE_REQ;
@@ -4364,7 +4364,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
mutex_lock(&fs_info->balance_mutex);
if (fs_info->balance_ctl) {
/* this is either (2) or (3) */
- if (!atomic_read(&fs_info->balance_running)) {
+ if (!test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)) {
mutex_unlock(&fs_info->balance_mutex);
/*
* Lock released to allow other waiters to continue,
@@ -4373,7 +4373,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
mutex_lock(&fs_info->balance_mutex);
if (fs_info->balance_ctl &&
- !atomic_read(&fs_info->balance_running)) {
+ !test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)) {
/* this is (3) */
need_unlock = false;
goto locked;