Btrfs: bring back balance pause/resume logic
Balance pause/resume logic got broken by 5ac00add (went in into 3.8-rc1
as part of dev-replace merge). Offending commit took a stab at making
mutually exclusive volume operations (add_dev, rm_dev, resize, balance,
replace_dev) not block behind volume_mutex if another such operation is
in progress and instead return an error right away. Balancing front-end
relied on the blocking behaviour, so the fix is ugly, but short of a
complete rework, it's the best we can do.
Reported-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 86279c3..9c84dbe 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2959,6 +2959,8 @@
unset_balance_control(fs_info);
ret = del_balance_item(fs_info->tree_root);
BUG_ON(ret);
+
+ atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
}
void update_ioctl_balance_args(struct btrfs_fs_info *fs_info, int lock,
@@ -3138,8 +3140,10 @@
out:
if (bctl->flags & BTRFS_BALANCE_RESUME)
__cancel_balance(fs_info);
- else
+ else {
kfree(bctl);
+ atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
+ }
return ret;
}
@@ -3156,7 +3160,6 @@
ret = btrfs_balance(fs_info->balance_ctl, NULL);
}
- atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
mutex_unlock(&fs_info->balance_mutex);
mutex_unlock(&fs_info->volume_mutex);
@@ -3179,7 +3182,6 @@
return 0;
}
- WARN_ON(atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1));
tsk = kthread_run(balance_kthread, fs_info, "btrfs-balance");
if (IS_ERR(tsk))
return PTR_ERR(tsk);
@@ -3233,6 +3235,8 @@
btrfs_balance_sys(leaf, item, &disk_bargs);
btrfs_disk_balance_args_to_cpu(&bctl->sys, &disk_bargs);
+ WARN_ON(atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1));
+
mutex_lock(&fs_info->volume_mutex);
mutex_lock(&fs_info->balance_mutex);