[PATCH 15/17] btrfs: zoned: avoid chunk allocation if active block group has enough space

@@ -3478,6 +3478,7 @@ struct find_free_extent_ctl {
 	/* Basic allocation info */
 	u64 ram_bytes;
 	u64 num_bytes;
+	u64 min_alloc_size;
 	u64 empty_size;
 	u64 flags;
 	int delalloc;

@@ -3946,18 +3947,29 @@ static int find_free_extent_update_loop(struct btrfs_fs_info *fs_info,
 	    ffe_ctl->have_caching_bg && !ffe_ctl->orig_have_caching_bg)
 		ffe_ctl->orig_have_caching_bg = true;
 
-	if (!ins->objectid && ffe_ctl->loop >= LOOP_CACHING_WAIT &&
-	    ffe_ctl->have_caching_bg)
-		return 1;
-
-	if (!ins->objectid && ++(ffe_ctl->index) < BTRFS_NR_RAID_TYPES)
-		return 1;
-
 	if (ins->objectid) {
 		found_extent(ffe_ctl, ins);
 		return 0;
 	}
 
+	if (ffe_ctl->max_extent_size >= ffe_ctl->min_alloc_size &&
+	    !btrfs_can_activate_zone(fs_info->fs_devices, ffe_ctl->index)) {
+		/*
+		 * If we have enough free space left in an already active
+		 * block group and we can't activate any other zone now,
+		 * retry the active ones with a smaller allocation size.
+		 * Returning early from here will tell
+		 * btrfs_reserve_extent() to haven the size.
+		 */
+		return -ENOSPC;
+	}
+
+	if (ffe_ctl->loop >= LOOP_CACHING_WAIT && ffe_ctl->have_caching_bg)
+		return 1;
+
+	if (++(ffe_ctl->index) < BTRFS_NR_RAID_TYPES)
+		return 1;
+
 	/*
 	 * LOOP_CACHING_NOWAIT, search partially cached block groups, kicking
 	 *			caching kthreads as we move along

@@ -4434,6 +4446,7 @@ int btrfs_reserve_extent(struct btrfs_root *root, u64 ram_bytes,
 
 	ffe_ctl.ram_bytes = ram_bytes;
 	ffe_ctl.num_bytes = num_bytes;
+	ffe_ctl.min_alloc_size = min_alloc_size;
 	ffe_ctl.empty_size = empty_size;
 	ffe_ctl.flags = flags;
 	ffe_ctl.delalloc = delalloc;

@@ -1865,3 +1865,35 @@ int btrfs_zone_finish(struct btrfs_block_group *block_group)
 
 	return ret;
 }
+
+bool btrfs_can_activate_zone(struct btrfs_fs_devices *fs_devices,
+			     int raid_index)
+{
+	struct btrfs_device *device;
+	bool ret = false;
+
+	if (!btrfs_is_zoned(fs_devices->fs_info))
+		return true;
+
+	/* Non-single profiles are not supported yet */
+	if (raid_index != BTRFS_RAID_SINGLE)
+		return false;
+
+	/* Check if there is a device with active zones left */
+	mutex_lock(&fs_devices->device_list_mutex);
+	list_for_each_entry(device, &fs_devices->devices, dev_list) {
+		struct btrfs_zoned_device_info *zinfo = device->zone_info;
+
+		if (!device->bdev)
+			continue;
+
+		if (!zinfo->max_active_zones ||
+		    atomic_read(&zinfo->active_zones_left)) {
+			ret = true;
+			break;
+		}
+	}
+	mutex_unlock(&fs_devices->device_list_mutex);
+
+	return ret;
+}

@@ -71,6 +71,8 @@ struct btrfs_device *btrfs_zoned_get_device(struct btrfs_fs_info *fs_info,
 					    u64 logical, u64 length);
 bool btrfs_zone_activate(struct btrfs_block_group *block_group);
 int btrfs_zone_finish(struct btrfs_block_group *block_group);
+bool btrfs_can_activate_zone(struct btrfs_fs_devices *fs_devices,
+			     int raid_index);
 #else /* CONFIG_BLK_DEV_ZONED */
 static inline int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
 				     struct blk_zone *zone)

@@ -216,6 +218,12 @@ static inline int btrfs_zone_finish(struct btrfs_block_group *block_group)
 	return 0;
 }
 
+static inline bool btrfs_can_activate_zone(struct btrfs_fs_devices *fs_devices,
+					   int raid_index)
+{
+	return true;
+}
+
 #endif
 
 static inline bool btrfs_dev_is_sequential(struct btrfs_device *device, u64 pos)