[PATCH v4 6/6] btrfs-progs: read stripe tree when mapping blocks

[Johannes Thumshirn <johannes.thumshirn@wdc.com>]

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 kernel-shared/volumes.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 113 insertions(+), 3 deletions(-)

diff --git a/kernel-shared/volumes.c b/kernel-shared/volumes.c
index 95d5930b95d8..2081f7db088f 100644
--- a/kernel-shared/volumes.c
+++ b/kernel-shared/volumes.c
@@ -1796,6 +1796,105 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
 				 multi_ret, mirror_num, raid_map_ret);
 }
 
+static bool btrfs_need_stripe_tree_update(struct btrfs_fs_info *fs_info,
+					u64 map_type)
+{
+#if EXPERIMENTAL
+	const bool is_data = (map_type & BTRFS_BLOCK_GROUP_DATA);
+
+	if (!btrfs_fs_incompat(fs_info, RAID_STRIPE_TREE))
+		return false;
+
+	if (!fs_info->stripe_root)
+		return false;
+
+	if (!is_data)
+		return false;
+
+	if (map_type & BTRFS_BLOCK_GROUP_DUP)
+		return true;
+
+	if (map_type & BTRFS_BLOCK_GROUP_RAID1_MASK)
+		return true;
+
+	if (map_type & BTRFS_BLOCK_GROUP_RAID0)
+		return true;
+
+	if (map_type & BTRFS_BLOCK_GROUP_RAID10)
+		return true;
+
+#endif
+	return false;
+}
+
+static int btrfs_stripe_tree_logical_to_physical(struct btrfs_fs_info *fs_info,
+						u64 logical,
+						struct btrfs_bio_stripe *stripe)
+{
+	struct btrfs_root *root = fs_info->stripe_root;
+	struct btrfs_path path = { 0 };
+	struct btrfs_key key;
+	struct extent_buffer *leaf;
+	int slot;
+	int ret;
+
+	key.objectid = logical;
+	key.type = BTRFS_RAID_STRIPE_KEY;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+	if (ret < 0)
+		return ret;
+
+	while (1) {
+		struct btrfs_key found_key;
+		struct btrfs_stripe_extent *extent;
+		int num_stripes;
+		u32 item_size;
+		int i;
+
+		leaf = path.nodes[0];
+		slot = path.slots[0];
+
+		if (slot >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, &path);
+			if (ret == 0)
+				continue;
+			if (ret < 0)
+				goto error;
+			break;
+		}
+
+		btrfs_item_key_to_cpu(leaf, &found_key, slot);
+
+		if (found_key.type != BTRFS_RAID_STRIPE_KEY)
+			goto next;
+
+		extent = btrfs_item_ptr(leaf, slot,
+					struct btrfs_stripe_extent);
+		item_size = btrfs_item_size(leaf, slot);
+		num_stripes = (item_size -
+			offsetof(struct btrfs_stripe_extent, strides)) /
+			sizeof(struct btrfs_raid_stride);
+
+		for (i = 0; i < num_stripes; i++) {
+			if (stripe->dev->devid !=
+				btrfs_raid_stride_devid_nr(leaf, extent, i))
+				continue;
+			stripe->physical = btrfs_raid_stride_offset_nr(leaf, extent, i);
+			btrfs_release_path(&path);
+			return 0;
+		}
+
+next:
+		path.slots[0]++;
+	}
+
+	btrfs_release_path(&path);
+error:
+	return ret;
+}
+
 int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
 		      u64 logical, u64 *length, u64 *type,
 		      struct btrfs_multi_bio **multi_ret, int mirror_num,
@@ -1988,10 +2087,21 @@ again:
 	BUG_ON(stripe_index >= map->num_stripes);
 
 	for (i = 0; i < multi->num_stripes; i++) {
-		multi->stripes[i].physical =
-			map->stripes[stripe_index].physical + stripe_offset +
-			stripe_nr * map->stripe_len;
 		multi->stripes[i].dev = map->stripes[stripe_index].dev;
+
+		if (stripes_allocated &&
+			btrfs_need_stripe_tree_update(fs_info, map->type)) {
+			int ret;
+
+			ret = btrfs_stripe_tree_logical_to_physical(fs_info, logical,
+								&multi->stripes[i]);
+			if (ret)
+				return ret;
+		} else {
+			multi->stripes[i].physical =
+				map->stripes[stripe_index].physical +
+				stripe_offset + stripe_nr * map->stripe_len;
+		}
 		stripe_index++;
 	}
 	*multi_ret = multi;

-- 
2.41.0