btrfs: add helper to calculate space for delayed references

Instead of duplicating the logic for calculating how much space is
required for a given number of delayed references, add an inline helper
to encapsulate that logic and use it everywhere we are calculating the
space required.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/delayed-ref.c

@@ -65,20 +65,9 @@ bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info)
 void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr)
 {
 	struct btrfs_block_rsv *block_rsv = &fs_info->delayed_refs_rsv;
-	u64 num_bytes = btrfs_calc_insert_metadata_size(fs_info, nr);
+	const u64 num_bytes = btrfs_calc_delayed_ref_bytes(fs_info, nr);
 	u64 released = 0;
 
-	/*
-	 * We have to check the mount option here because we could be enabling
-	 * the free space tree for the first time and don't have the compat_ro
-	 * option set yet.
-	 *
-	 * We need extra reservations if we have the free space tree because
-	 * we'll have to modify that tree as well.
-	 */
-	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
-		num_bytes *= 2;
-
 	released = btrfs_block_rsv_release(fs_info, block_rsv, num_bytes, NULL);
 	if (released)
 		trace_btrfs_space_reservation(fs_info, "delayed_refs_rsv",
@@ -100,18 +89,8 @@ void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans)
 	if (!trans->delayed_ref_updates)
 		return;
 
-	num_bytes = btrfs_calc_insert_metadata_size(fs_info,
-						    trans->delayed_ref_updates);
-	/*
-	 * We have to check the mount option here because we could be enabling
-	 * the free space tree for the first time and don't have the compat_ro
-	 * option set yet.
-	 *
-	 * We need extra reservations if we have the free space tree because
-	 * we'll have to modify that tree as well.
-	 */
-	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
-		num_bytes *= 2;
+	num_bytes = btrfs_calc_delayed_ref_bytes(fs_info,
+						 trans->delayed_ref_updates);
 
 	spin_lock(&delayed_rsv->lock);
 	delayed_rsv->size += num_bytes;
@@ -182,21 +161,10 @@ int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
 				  enum btrfs_reserve_flush_enum flush)
 {
 	struct btrfs_block_rsv *block_rsv = &fs_info->delayed_refs_rsv;
-	u64 limit = btrfs_calc_insert_metadata_size(fs_info, 1);
+	u64 limit = btrfs_calc_delayed_ref_bytes(fs_info, 1);
 	u64 num_bytes = 0;
 	int ret = -ENOSPC;
 
-	/*
-	 * We have to check the mount option here because we could be enabling
-	 * the free space tree for the first time and don't have the compat_ro
-	 * option set yet.
-	 *
-	 * We need extra reservations if we have the free space tree because
-	 * we'll have to modify that tree as well.
-	 */
-	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
-		limit *= 2;
-
 	spin_lock(&block_rsv->lock);
 	if (block_rsv->reserved < block_rsv->size) {
 		num_bytes = block_rsv->size - block_rsv->reserved;

fs/btrfs/delayed-ref.h

@@ -253,6 +253,27 @@ extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 int __init btrfs_delayed_ref_init(void);
 void __cold btrfs_delayed_ref_exit(void);
 
+static inline u64 btrfs_calc_delayed_ref_bytes(const struct btrfs_fs_info *fs_info,
+					       int num_delayed_refs)
+{
+	u64 num_bytes;
+
+	num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_delayed_refs);
+
+	/*
+	 * We have to check the mount option here because we could be enabling
+	 * the free space tree for the first time and don't have the compat_ro
+	 * option set yet.
+	 *
+	 * We need extra reservations if we have the free space tree because
+	 * we'll have to modify that tree as well.
+	 */
+	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
+		num_bytes *= 2;
+
+	return num_bytes;
+}
+
 static inline void btrfs_init_generic_ref(struct btrfs_ref *generic_ref,
 				int action, u64 bytenr, u64 len, u64 parent)
 {

fs/btrfs/space-info.c

@@ -553,21 +553,9 @@ static inline u64 calc_reclaim_items_nr(const struct btrfs_fs_info *fs_info,
 static inline u64 calc_delayed_refs_nr(const struct btrfs_fs_info *fs_info,
 				       u64 to_reclaim)
 {
-	u64 bytes;
+	const u64 bytes = btrfs_calc_delayed_ref_bytes(fs_info, 1);
 	u64 nr;
 
-	bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
-	/*
-	 * We have to check the mount option here because we could be enabling
-	 * the free space tree for the first time and don't have the compat_ro
-	 * option set yet.
-	 *
-	 * We need extra reservations if we have the free space tree because
-	 * we'll have to modify that tree as well.
-	 */
-	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
-		bytes *= 2;
-
 	nr = div64_u64(to_reclaim, bytes);
 	if (!nr)
 		nr = 1;