3 files changed, 69 insertions, 0 deletions

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 310b7d817a27..6de508323dbd 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -3859,6 +3859,56 @@ static const char *stage_to_string(enum reloc_stage stage)
 	return "unknown";
 }
 
+int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical, u64 *length)
+{
+	int ret;
+	struct btrfs_key key, found_key;
+	struct extent_buffer *leaf;
+	struct btrfs_remap_item *remap;
+	BTRFS_PATH_AUTO_FREE(path);
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	key.objectid = *logical;
+	key.type = (u8)-1;
+	key.offset = (u64)-1;
+
+	ret = btrfs_search_slot(NULL, fs_info->remap_root, &key, path, 0, 0);
+	if (ret < 0)
+		return ret;
+
+	leaf = path->nodes[0];
+	if (path->slots[0] == 0)
+		return -ENOENT;
+
+	path->slots[0]--;
+
+	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+
+	if (found_key.type != BTRFS_REMAP_KEY &&
+	    found_key.type != BTRFS_IDENTITY_REMAP_KEY) {
+		return -ENOENT;
+	}
+
+	if (found_key.objectid > *logical ||
+	    found_key.objectid + found_key.offset <= *logical) {
+		return -ENOENT;
+	}
+
+	if (*logical + *length > found_key.objectid + found_key.offset)
+		*length = found_key.objectid + found_key.offset - *logical;
+
+	if (found_key.type == BTRFS_IDENTITY_REMAP_KEY)
+		return 0;
+
+	remap = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_remap_item);
+	*logical += btrfs_remap_address(leaf, remap) - found_key.objectid;
+
+	return 0;
+}
+
 /*
  * function to relocate all extents in a block group.
  */
diff --git a/fs/btrfs/relocation.h b/fs/btrfs/relocation.h
index 5c36b3f84b57..c0ee26004fc1 100644
--- a/fs/btrfs/relocation.h
+++ b/fs/btrfs/relocation.h
@@ -31,5 +31,6 @@ int btrfs_should_cancel_balance(const struct btrfs_fs_info *fs_info);
 struct btrfs_root *find_reloc_root(struct btrfs_fs_info *fs_info, u64 bytenr);
 bool btrfs_should_ignore_reloc_root(const struct btrfs_root *root);
 u64 btrfs_get_reloc_bg_bytenr(const struct btrfs_fs_info *fs_info);
+int btrfs_translate_remap(struct btrfs_fs_info *fs_info, u64 *logical, u64 *length);
 
 #endif
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6280a1a4c407..2a4bda452d85 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6586,6 +6586,24 @@ int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 	if (IS_ERR(map))
 		return PTR_ERR(map);
 
+	if (map->type & BTRFS_BLOCK_GROUP_REMAPPED) {
+		u64 new_logical = logical;
+
+		ret = btrfs_translate_remap(fs_info, &new_logical, length);
+		if (ret)
+			return ret;
+
+		if (new_logical != logical) {
+			btrfs_free_chunk_map(map);
+
+			map = btrfs_get_chunk_map(fs_info, new_logical, *length);
+			if (IS_ERR(map))
+				return PTR_ERR(map);
+
+			logical = new_logical;
+		}
+	}
+
 	num_copies = btrfs_chunk_map_num_copies(map);
 	if (io_geom.mirror_num > num_copies)
 		return -EINVAL;