btrfs: qgroup: Split meta rsv type into meta_prealloc and meta_pertrans

Btrfs uses 2 different methods to reseve metadata qgroup space.

1) Reserve at btrfs_start_transaction() time
   This is quite straightforward, caller will use the trans handler
   allocated to modify b-trees.

   In this case, reserved metadata should be kept until qgroup numbers
   are updated.

2) Reserve by using block_rsv first, and later btrfs_join_transaction()
   This is more complicated, caller will reserve space using block_rsv
   first, and then later call btrfs_join_transaction() to get a trans
   handle.

   In this case, before we modify trees, the reserved space can be
   modified on demand, and after btrfs_join_transaction(), such reserved
   space should also be kept until qgroup numbers are updated.

Since these two types behave differently, split the original "META"
reservation type into 2 sub-types:

  META_PERTRANS:
    For above case 1)

  META_PREALLOC:
    For reservations that happened before btrfs_join_transaction() of
    case 2)

NOTE: This patch will only convert existing qgroup meta reservation
callers according to its situation, not ensuring all callers are at
correct timing.
Such fix will be added in later patches.

Signed-off-by: Qu Wenruo <wqu@suse.com>
[ update comments ]
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 12 insertions, 10 deletions

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index c0deebfecd93..8831eaa14204 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -69,8 +69,10 @@ static const char *qgroup_rsv_type_str(enum btrfs_qgroup_rsv_type type)
 {
 	if (type == BTRFS_QGROUP_RSV_DATA)
 		return "data";
-	if (type == BTRFS_QGROUP_RSV_META)
-		return "meta";
+	if (type == BTRFS_QGROUP_RSV_META_PERTRANS)
+		return "meta_pertrans";
+	if (type == BTRFS_QGROUP_RSV_META_PREALLOC)
+		return "meta_prealloc";
 	return NULL;
 }
 #endif
@@ -3065,8 +3067,8 @@ int btrfs_qgroup_release_data(struct inode *inode, u64 start, u64 len)
 	return __btrfs_qgroup_release_data(inode, NULL, start, len, 0);
 }
 
-int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
-			      bool enforce)
+int __btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
+				enum btrfs_qgroup_rsv_type type, bool enforce)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	int ret;
@@ -3077,14 +3079,14 @@ int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
 
 	BUG_ON(num_bytes != round_down(num_bytes, fs_info->nodesize));
 	trace_qgroup_meta_reserve(root, (s64)num_bytes);
-	ret = qgroup_reserve(root, num_bytes, enforce, BTRFS_QGROUP_RSV_META);
+	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(struct btrfs_root *root)
+void btrfs_qgroup_free_meta_all_pertrans(struct btrfs_root *root)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	u64 reserved;
@@ -3098,10 +3100,11 @@ void btrfs_qgroup_free_meta_all(struct btrfs_root *root)
 		return;
 	trace_qgroup_meta_reserve(root, -(s64)reserved);
 	btrfs_qgroup_free_refroot(fs_info, root->objectid, reserved,
-				  BTRFS_QGROUP_RSV_META);
+				  BTRFS_QGROUP_RSV_META_PERTRANS);
 }
 
-void btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes)
+void __btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes,
+			      enum btrfs_qgroup_rsv_type type)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
 
@@ -3113,8 +3116,7 @@ void btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes)
 	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,
-				  BTRFS_QGROUP_RSV_META);
+	btrfs_qgroup_free_refroot(fs_info, root->objectid, num_bytes, type);
 }
 
 /*