fs: btrfs: Add single-device read-only BTRFS implementation

This adds the proper implementation for the BTRFS filesystem.
The implementation currently supports only read-only mode and
the filesystem can be only on a single device.

Checksums of data chunks is unimplemented.

Compression is implemented (ZLIB + LZO).

Signed-off-by: Marek Behun <[email protected]>

 create mode 100644 fs/btrfs/btrfs.h
 create mode 100644 fs/btrfs/chunk-map.c
 create mode 100644 fs/btrfs/compression.c
 create mode 100644 fs/btrfs/ctree.c
 create mode 100644 fs/btrfs/dev.c
 create mode 100644 fs/btrfs/dir-item.c
 create mode 100644 fs/btrfs/extent-io.c
 create mode 100644 fs/btrfs/hash.c
 create mode 100644 fs/btrfs/inode.c
 create mode 100644 fs/btrfs/root.c
 create mode 100644 fs/btrfs/subvolume.c
 create mode 100644 fs/btrfs/super.c

fs/btrfs/btrfs.h

@@ -0,0 +1,89 @@
+/*
+ * BTRFS filesystem implementation for U-Boot
+ *
+ * 2017 Marek Behun, CZ.NIC, [email protected]
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __BTRFS_BTRFS_H__
+#define __BTRFS_BTRFS_H__
+
+#include <linux/rbtree.h>
+#include "conv-funcs.h"
+
+struct btrfs_info {
+	struct btrfs_super_block sb;
+	struct btrfs_root_backup *root_backup;
+
+	struct btrfs_root tree_root;
+	struct btrfs_root fs_root;
+	struct btrfs_root chunk_root;
+
+	struct rb_root chunks_root;
+};
+
+extern struct btrfs_info btrfs_info;
+
+/* hash.c */
+void btrfs_hash_init(void);
+u32 btrfs_crc32c(u32, const void *, size_t);
+u32 btrfs_csum_data(char *, u32, size_t);
+void btrfs_csum_final(u32, void *);
+
+static inline u64 btrfs_name_hash(const char *name, int len)
+{
+	return btrfs_crc32c((u32) ~1, name, len);
+}
+
+/* dev.c */
+extern struct blk_desc *btrfs_blk_desc;
+extern disk_partition_t *btrfs_part_info;
+
+int btrfs_devread(u64, int, void *);
+
+/* chunk-map.c */
+u64 btrfs_map_logical_to_physical(u64);
+int btrfs_chunk_map_init(void);
+void btrfs_chunk_map_exit(void);
+int btrfs_read_chunk_tree(void);
+
+/* compression.c */
+u32 btrfs_decompress(u8 type, const char *, u32, char *, u32);
+
+/* super.c */
+int btrfs_read_superblock(void);
+
+/* dir-item.c */
+typedef int (*btrfs_readdir_callback_t)(const struct btrfs_root *,
+					struct btrfs_dir_item *);
+
+int btrfs_lookup_dir_item(const struct btrfs_root *, u64, const char *, int,
+			   struct btrfs_dir_item *);
+int btrfs_readdir(const struct btrfs_root *, u64, btrfs_readdir_callback_t);
+
+/* root.c */
+int btrfs_find_root(u64, struct btrfs_root *, struct btrfs_root_item *);
+u64 btrfs_lookup_root_ref(u64, struct btrfs_root_ref *, char *);
+
+/* inode.c */
+u64 btrfs_lookup_inode_ref(struct btrfs_root *, u64, struct btrfs_inode_ref *,
+			    char *);
+int btrfs_lookup_inode(const struct btrfs_root *, struct btrfs_key *,
+		        struct btrfs_inode_item *, struct btrfs_root *);
+int btrfs_readlink(const struct btrfs_root *, u64, char *);
+u64 btrfs_lookup_path(struct btrfs_root *, u64, const char *, u8 *,
+		       struct btrfs_inode_item *, int);
+u64 btrfs_file_read(const struct btrfs_root *, u64, u64, u64, char *);
+
+/* subvolume.c */
+u64 btrfs_get_default_subvol_objectid(void);
+
+/* extent-io.c */
+u64 btrfs_read_extent_inline(struct btrfs_path *,
+			      struct btrfs_file_extent_item *, u64, u64,
+			      char *);
+u64 btrfs_read_extent_reg(struct btrfs_path *, struct btrfs_file_extent_item *,
+			   u64, u64, char *);
+
+#endif /* !__BTRFS_BTRFS_H__ */

fs/btrfs/chunk-map.c

@@ -0,0 +1,178 @@
+/*
+ * BTRFS filesystem implementation for U-Boot
+ *
+ * 2017 Marek Behun, CZ.NIC, [email protected]
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include "btrfs.h"
+#include <malloc.h>
+
+struct chunk_map_item {
+	struct rb_node node;
+	u64 logical;
+	u64 length;
+	u64 physical;
+};
+
+static int add_chunk_mapping(struct btrfs_key *key, struct btrfs_chunk *chunk)
+{
+	struct btrfs_stripe *stripe;
+	u64 block_profile = chunk->type & BTRFS_BLOCK_GROUP_PROFILE_MASK;
+	struct rb_node **new = &(btrfs_info.chunks_root.rb_node), *prnt = NULL;
+	struct chunk_map_item *map_item;
+
+	if (block_profile && block_profile != BTRFS_BLOCK_GROUP_DUP) {
+		printf("%s: unsupported chunk profile %llu\n", __func__,
+		       block_profile);
+		return -1;
+	} else if (!chunk->length) {
+		printf("%s: zero length chunk\n", __func__);
+		return -1;
+	}
+
+	stripe = &chunk->stripe;
+	btrfs_stripe_to_cpu(stripe);
+
+	while (*new) {
+		struct chunk_map_item *this;
+
+		this = rb_entry(*new, struct chunk_map_item, node);
+
+		prnt = *new;
+		if (key->offset < this->logical) {
+			new = &((*new)->rb_left);
+		} else if (key->offset > this->logical) {
+			new = &((*new)->rb_right);
+		} else {
+			debug("%s: Logical address %llu already in map!\n",
+			      __func__, key->offset);
+			return 0;
+		}
+	}
+
+	map_item = malloc(sizeof(struct chunk_map_item));
+	if (!map_item)
+		return -1;
+
+	map_item->logical = key->offset;
+	map_item->length = chunk->length;
+	map_item->physical = le64_to_cpu(chunk->stripe.offset);
+	rb_link_node(&map_item->node, prnt, new);
+	rb_insert_color(&map_item->node, &btrfs_info.chunks_root);
+
+	debug("%s: Mapping %llu to %llu\n", __func__, map_item->logical,
+	      map_item->physical);
+
+	return 0;
+}
+
+u64 btrfs_map_logical_to_physical(u64 logical)
+{
+	struct rb_node *node = btrfs_info.chunks_root.rb_node;
+
+	while (node) {
+		struct chunk_map_item *item;
+
+		item = rb_entry(node, struct chunk_map_item, node);
+
+		if (item->logical > logical)
+			node = node->rb_left;
+		else if (logical > item->logical + item->length)
+			node = node->rb_right;
+		else
+			return item->physical + logical - item->logical;
+	}
+
+	printf("%s: Cannot map logical address %llu to physical\n", __func__,
+	       logical);
+
+	return -1ULL;
+}
+
+void btrfs_chunk_map_exit(void)
+{
+	struct rb_node *now, *next;
+	struct chunk_map_item *item;
+
+	for (now = rb_first_postorder(&btrfs_info.chunks_root); now; now = next)
+	{
+		item = rb_entry(now, struct chunk_map_item, node);
+		next = rb_next_postorder(now);
+		free(item);
+	}
+}
+
+int btrfs_chunk_map_init(void)
+{
+	u8 sys_chunk_array_copy[sizeof(btrfs_info.sb.sys_chunk_array)];
+	u8 * const start = sys_chunk_array_copy;
+	u8 * const end = start + btrfs_info.sb.sys_chunk_array_size;
+	u8 *cur;
+	struct btrfs_key *key;
+	struct btrfs_chunk *chunk;
+
+	btrfs_info.chunks_root = RB_ROOT;
+
+	memcpy(sys_chunk_array_copy, btrfs_info.sb.sys_chunk_array,
+	       sizeof(sys_chunk_array_copy));
+
+	for (cur = start; cur < end;) {
+		key = (struct btrfs_key *) cur;
+		cur += sizeof(struct btrfs_key);
+		chunk = (struct btrfs_chunk *) cur;
+
+		btrfs_key_to_cpu(key);
+		btrfs_chunk_to_cpu(chunk);
+
+		if (key->type != BTRFS_CHUNK_ITEM_KEY) {
+			printf("%s: invalid key type %u\n", __func__,
+			       key->type);
+			return -1;
+		}
+
+		if (add_chunk_mapping(key, chunk))
+			return -1;
+
+		cur += sizeof(struct btrfs_chunk);
+		cur += sizeof(struct btrfs_stripe) * (chunk->num_stripes - 1);
+	}
+
+	return 0;
+}
+
+int btrfs_read_chunk_tree(void)
+{
+	struct btrfs_path path;
+	struct btrfs_key key, *found_key;
+	struct btrfs_chunk *chunk;
+	int res;
+
+	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+	key.type = BTRFS_CHUNK_ITEM_KEY;
+	key.offset = 0;
+
+	if (btrfs_search_tree(&btrfs_info.chunk_root, &key, &path))
+		return -1;
+
+	do {
+		found_key = btrfs_path_leaf_key(&path);
+		if (btrfs_comp_keys_type(&key, found_key))
+			break;
+
+		chunk = btrfs_path_item_ptr(&path, struct btrfs_chunk);
+		btrfs_chunk_to_cpu(chunk);
+		if (add_chunk_mapping(found_key, chunk)) {
+			res = -1;
+			break;
+		}
+	} while (!(res = btrfs_next_slot(&path)));
+
+	btrfs_free_path(&path);
+
+	if (res < 0)
+		return -1;
+
+	return 0;
+}