From e1211d0e896b71d395fe411d0e0a76f4bc336617 Mon Sep 17 00:00:00 2001
From: Qu Wenruo <wqu@suse.com>
Date: Tue, 12 Dec 2017 15:34:30 +0800
Patch-mainline: v4.17-rc1
Git-commit: e1211d0e896b71d395fe411d0e0a76f4bc336617
References: bsc#1031392
Subject: [PATCH 14/16] btrfs: qgroup: Don't use root->qgroup_meta_rsv for
 qgroup

Since qgroup has seperate metadata reservation types now, we can
completely get rid of the old root->qgroup_meta_rsv, which mostly acts
as current META_PERTRANS reservation type.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/ctree.h   |    3 ---
 fs/btrfs/disk-io.c |    1 -
 fs/btrfs/qgroup.c  |   33 ++++++++++++++++++++++++---------
 3 files changed, 24 insertions(+), 13 deletions(-)

--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1309,9 +1309,6 @@ struct btrfs_root {
 	int send_in_progress;
 	struct btrfs_subvolume_writers *subv_writers;
 	atomic_t will_be_snapshoted;
-
-	/* For qgroup metadata space reserve */
-	atomic64_t qgroup_meta_rsv;
 };
 
 struct btrfs_file_private {
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1283,7 +1283,6 @@ static void __setup_root(struct btrfs_ro
 	atomic_set(&root->orphan_inodes, 0);
 	refcount_set(&root->refs, 1);
 	atomic_set(&root->will_be_snapshoted, 0);
-	atomic64_set(&root->qgroup_meta_rsv, 0);
 	root->log_transid = 0;
 	root->log_transid_committed = -1;
 	root->last_log_commit = 0;
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2526,6 +2526,15 @@ out:
 	return ret;
 }
 
+/*
+ * Free @num_bytes of reserved space with @type for qgroup.  (Normally level 0
+ * qgroup).
+ *
+ * Will handle all higher level qgroup too.
+ *
+ * NOTE: If @num_bytes is (u64)-1, this means to free all bytes of this qgroup.
+ * This special case is only used for META_PERTRANS type.
+ */
 void btrfs_qgroup_free_refroot(struct btrfs_fs_info *fs_info,
 			       u64 ref_root, u64 num_bytes,
 			       enum btrfs_qgroup_rsv_type type)
@@ -2542,6 +2551,10 @@ void btrfs_qgroup_free_refroot(struct bt
 	if (num_bytes == 0)
 		return;
 
+	if (num_bytes == (u64)-1 && type != BTRFS_QGROUP_RSV_META_PERTRANS) {
+		WARN(1, "%s: Invalid type to free", __func__);
+		return;
+	}
 	spin_lock(&fs_info->qgroup_lock);
 
 	quota_root = fs_info->quota_root;
@@ -2552,6 +2565,13 @@ void btrfs_qgroup_free_refroot(struct bt
 	if (!qgroup)
 		goto out;
 
+	/*
+	 * We're freeing all pertrans rsv, get current value from level 0
+	 * qgroup as real num_bytes to free.
+	 */
+	if (num_bytes == (u64)-1)
+		num_bytes = qgroup->rsv.values[type];
+
 	ulist_reinit(fs_info->qgroup_ulist);
 	ret = ulist_add(fs_info->qgroup_ulist, qgroup->qgroupid,
 			(uintptr_t)qgroup, GFP_ATOMIC);
@@ -3167,24 +3187,21 @@ int __btrfs_qgroup_reserve_meta(struct b
 	ret = qgroup_reserve(root, num_bytes, enforce, type);
 	if (ret < 0)
 		return ret;
-	atomic64_add(num_bytes, &root->qgroup_meta_rsv);
 	return ret;
 }
 
 void btrfs_qgroup_free_meta_all_pertrans(struct btrfs_root *root)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
-	u64 reserved;
 
 	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) ||
 	    !is_fstree(root->objectid))
 		return;
 
-	reserved = atomic64_xchg(&root->qgroup_meta_rsv, 0);
-	if (reserved == 0)
-		return;
-	trace_qgroup_meta_reserve(root, -(s64)reserved);
-	btrfs_qgroup_free_refroot(fs_info, root->objectid, reserved,
+	/* TODO: Update trace point to handle such free */
+	trace_qgroup_meta_reserve(root, 0);
+	/* Special value -1 means to free all reserved space */
+	btrfs_qgroup_free_refroot(fs_info, root->objectid, (u64)-1,
 				  BTRFS_QGROUP_RSV_META_PERTRANS);
 }
 
@@ -3198,8 +3215,6 @@ void __btrfs_qgroup_free_meta(struct btr
 		return;
 
 	BUG_ON(num_bytes != round_down(num_bytes, fs_info->nodesize));
-	WARN_ON(atomic64_read(&root->qgroup_meta_rsv) < num_bytes);
-	atomic64_sub(num_bytes, &root->qgroup_meta_rsv);
 	trace_qgroup_meta_reserve(root, -(s64)num_bytes);
 	btrfs_qgroup_free_refroot(fs_info, root->objectid, num_bytes, type);
 }