3 files changed, 87 insertions, 10 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 166ce2c539aa..5b604c3dc357 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3965,6 +3965,45 @@ static void found_extent(struct find_free_extent_ctl *ffe_ctl,
 	}
 }
 
+static int can_allocate_chunk_zoned(struct btrfs_fs_info *fs_info,
+				    struct find_free_extent_ctl *ffe_ctl)
+{
+	/* If we can activate new zone, just allocate a chunk and use it */
+	if (btrfs_can_activate_zone(fs_info->fs_devices, ffe_ctl->flags))
+		return 0;
+
+	/*
+	 * We already reached the max active zones. Try to finish one block
+	 * group to make a room for a new block group. This is only possible
+	 * for a data block group because btrfs_zone_finish() may need to wait
+	 * for a running transaction which can cause a deadlock for metadata
+	 * allocation.
+	 */
+	if (ffe_ctl->flags & BTRFS_BLOCK_GROUP_DATA) {
+		int ret = btrfs_zone_finish_one_bg(fs_info);
+
+		if (ret == 1)
+			return 0;
+		else if (ret < 0)
+			return ret;
+	}
+
+	/*
+	 * If we have enough free space left in an already active block group
+	 * and we can't activate any other zone now, do not allow allocating a
+	 * new chunk and let find_free_extent() retry with a smaller size.
+	 */
+	if (ffe_ctl->max_extent_size >= ffe_ctl->min_alloc_size)
+		return -ENOSPC;
+
+	/*
+	 * We cannot activate a new block group and no enough space left in any
+	 * block groups. So, allocating a new block group may not help. But,
+	 * there is nothing to do anyway, so let's go with it.
+	 */
+	return 0;
+}
+
 static int can_allocate_chunk(struct btrfs_fs_info *fs_info,
 			      struct find_free_extent_ctl *ffe_ctl)
 {
@@ -3972,16 +4011,7 @@ static int can_allocate_chunk(struct btrfs_fs_info *fs_info,
 	case BTRFS_EXTENT_ALLOC_CLUSTERED:
 		return 0;
 	case BTRFS_EXTENT_ALLOC_ZONED:
-		/*
-		 * If we have enough free space left in an already
-		 * active block group and we can't activate any other
-		 * zone now, do not allow allocating a new chunk and
-		 * let find_free_extent() retry with a smaller size.
-		 */
-		if (ffe_ctl->max_extent_size >= ffe_ctl->min_alloc_size &&
-		    !btrfs_can_activate_zone(fs_info->fs_devices, ffe_ctl->flags))
-			return -ENOSPC;
-		return 0;
+		return can_allocate_chunk_zoned(fs_info, ffe_ctl);
 	default:
 		BUG();
 	}
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index d8a0a522b3ca..35f6f8988494 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -2180,3 +2180,43 @@ out:
 	spin_unlock(&block_group->lock);
 	btrfs_put_block_group(block_group);
 }
+
+int btrfs_zone_finish_one_bg(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_block_group *block_group;
+	struct btrfs_block_group *min_bg = NULL;
+	u64 min_avail = U64_MAX;
+	int ret;
+
+	spin_lock(&fs_info->zone_active_bgs_lock);
+	list_for_each_entry(block_group, &fs_info->zone_active_bgs,
+			    active_bg_list) {
+		u64 avail;
+
+		spin_lock(&block_group->lock);
+		if (block_group->reserved ||
+		    (block_group->flags & BTRFS_BLOCK_GROUP_SYSTEM)) {
+			spin_unlock(&block_group->lock);
+			continue;
+		}
+
+		avail = block_group->zone_capacity - block_group->alloc_offset;
+		if (min_avail > avail) {
+			if (min_bg)
+				btrfs_put_block_group(min_bg);
+			min_bg = block_group;
+			min_avail = avail;
+			btrfs_get_block_group(min_bg);
+		}
+		spin_unlock(&block_group->lock);
+	}
+	spin_unlock(&fs_info->zone_active_bgs_lock);
+
+	if (!min_bg)
+		return 0;
+
+	ret = btrfs_zone_finish(min_bg);
+	btrfs_put_block_group(min_bg);
+
+	return ret < 0 ? ret : 1;
+}
diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
index 9caeab07fd38..329d28e2fd8d 100644
--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h
@@ -80,6 +80,7 @@ void btrfs_free_zone_cache(struct btrfs_fs_info *fs_info);
 bool btrfs_zoned_should_reclaim(struct btrfs_fs_info *fs_info);
 void btrfs_zoned_release_data_reloc_bg(struct btrfs_fs_info *fs_info, u64 logical,
 				       u64 length);
+int btrfs_zone_finish_one_bg(struct btrfs_fs_info *fs_info);
 #else /* CONFIG_BLK_DEV_ZONED */
 static inline int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
 				     struct blk_zone *zone)
@@ -249,6 +250,12 @@ static inline bool btrfs_zoned_should_reclaim(struct btrfs_fs_info *fs_info)
 
 static inline void btrfs_zoned_release_data_reloc_bg(struct btrfs_fs_info *fs_info,
 						     u64 logical, u64 length) { }
+
+static inline int btrfs_zone_finish_one_bg(struct btrfs_fs_info *fs_info)
+{
+	return 1;
+}
+
 #endif
 
 static inline bool btrfs_dev_is_sequential(struct btrfs_device *device, u64 pos)