fs: btrfs: Crossport btrfs_read_dev_super() from btrfs-progs

This patch uses generic code from btrfs-progs to read one super block
from block device.

To support the btrfs-progs coding style, the following is also
crossported:
- BTRFS_SETGET_FUNC for btrfs_super_block
- btrfs_check_super() function
- Move btrfs_read_superblock() to disk-io.[ch]
  Since super.c only contains pretty small amount of code, and
  the extra check will be covered in later root read patches.

Differences between this implementation and btrfs-progs:
- No sbflags/sb_bytenr support
  Since we only need to read the primary super block (like kernel),
  sbflags/sb_bytenr used by super block recovery is not needed.

This also changes the following behavior of U-Boot btrfs:
- Only reads the primary super block
  The old implementation reads all 3 super blocks, and also one
  non-existing backup.
  This is not correct, especially if there is another filesystem created
  on the device but old superblocks are not rewritten.

  Just like kernel, we only check the primary super block.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
[trini: Change error to be a define in compat.h]
Signed-off-by: Tom Rini <trini@konsulko.com>

1 files changed, 213 insertions, 0 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 58c32b548e5..edebf741fd2 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1,7 +1,12 @@
 // SPDX-License-Identifier: GPL-2.0+
 #include <common.h>
 #include <fs_internal.h>
+#include <uuid.h>
+#include <memalign.h>
+#include "kernel-shared/btrfs_tree.h"
 #include "disk-io.h"
+#include "ctree.h"
+#include "btrfs.h"
 #include "crypto/hash.h"
 
 int btrfs_csum_data(u16 csum_type, const u8 *data, u8 *out, size_t len)
@@ -20,3 +25,211 @@ int btrfs_csum_data(u16 csum_type, const u8 *data, u8 *out, size_t len)
 		return -EINVAL;
 	}
 }
+
+/*
+ * Check if the super is valid:
+ * - nodesize/sectorsize - minimum, maximum, alignment
+ * - tree block starts   - alignment
+ * - number of devices   - something sane
+ * - sys array size      - maximum
+ */
+static int btrfs_check_super(struct btrfs_super_block *sb)
+{
+	u8 result[BTRFS_CSUM_SIZE];
+	u16 csum_type;
+	int csum_size;
+	u8 *metadata_uuid;
+
+	if (btrfs_super_magic(sb) != BTRFS_MAGIC)
+		return -EIO;
+
+	csum_type = btrfs_super_csum_type(sb);
+	if (csum_type >= btrfs_super_num_csums()) {
+		error("unsupported checksum algorithm %u", csum_type);
+		return -EIO;
+	}
+	csum_size = btrfs_super_csum_size(sb);
+
+	btrfs_csum_data(csum_type, (u8 *)sb + BTRFS_CSUM_SIZE,
+			result, BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
+
+	if (memcmp(result, sb->csum, csum_size)) {
+		error("superblock checksum mismatch");
+		return -EIO;
+	}
+	if (btrfs_super_root_level(sb) >= BTRFS_MAX_LEVEL) {
+		error("tree_root level too big: %d >= %d",
+			btrfs_super_root_level(sb), BTRFS_MAX_LEVEL);
+		goto error_out;
+	}
+	if (btrfs_super_chunk_root_level(sb) >= BTRFS_MAX_LEVEL) {
+		error("chunk_root level too big: %d >= %d",
+			btrfs_super_chunk_root_level(sb), BTRFS_MAX_LEVEL);
+		goto error_out;
+	}
+	if (btrfs_super_log_root_level(sb) >= BTRFS_MAX_LEVEL) {
+		error("log_root level too big: %d >= %d",
+			btrfs_super_log_root_level(sb), BTRFS_MAX_LEVEL);
+		goto error_out;
+	}
+
+	if (!IS_ALIGNED(btrfs_super_root(sb), 4096)) {
+		error("tree_root block unaligned: %llu", btrfs_super_root(sb));
+		goto error_out;
+	}
+	if (!IS_ALIGNED(btrfs_super_chunk_root(sb), 4096)) {
+		error("chunk_root block unaligned: %llu",
+			btrfs_super_chunk_root(sb));
+		goto error_out;
+	}
+	if (!IS_ALIGNED(btrfs_super_log_root(sb), 4096)) {
+		error("log_root block unaligned: %llu",
+			btrfs_super_log_root(sb));
+		goto error_out;
+	}
+	if (btrfs_super_nodesize(sb) < 4096) {
+		error("nodesize too small: %u < 4096",
+			btrfs_super_nodesize(sb));
+		goto error_out;
+	}
+	if (!IS_ALIGNED(btrfs_super_nodesize(sb), 4096)) {
+		error("nodesize unaligned: %u", btrfs_super_nodesize(sb));
+		goto error_out;
+	}
+	if (btrfs_super_sectorsize(sb) < 4096) {
+		error("sectorsize too small: %u < 4096",
+			btrfs_super_sectorsize(sb));
+		goto error_out;
+	}
+	if (!IS_ALIGNED(btrfs_super_sectorsize(sb), 4096)) {
+		error("sectorsize unaligned: %u", btrfs_super_sectorsize(sb));
+		goto error_out;
+	}
+	if (btrfs_super_total_bytes(sb) == 0) {
+		error("invalid total_bytes 0");
+		goto error_out;
+	}
+	if (btrfs_super_bytes_used(sb) < 6 * btrfs_super_nodesize(sb)) {
+		error("invalid bytes_used %llu", btrfs_super_bytes_used(sb));
+		goto error_out;
+	}
+	if ((btrfs_super_stripesize(sb) != 4096)
+		&& (btrfs_super_stripesize(sb) != btrfs_super_sectorsize(sb))) {
+		error("invalid stripesize %u", btrfs_super_stripesize(sb));
+		goto error_out;
+	}
+
+	if (btrfs_super_incompat_flags(sb) & BTRFS_FEATURE_INCOMPAT_METADATA_UUID)
+		metadata_uuid = sb->metadata_uuid;
+	else
+		metadata_uuid = sb->fsid;
+
+	if (memcmp(metadata_uuid, sb->dev_item.fsid, BTRFS_FSID_SIZE) != 0) {
+		char fsid[BTRFS_UUID_UNPARSED_SIZE];
+		char dev_fsid[BTRFS_UUID_UNPARSED_SIZE];
+
+		uuid_unparse(sb->metadata_uuid, fsid);
+		uuid_unparse(sb->dev_item.fsid, dev_fsid);
+		error("dev_item UUID does not match fsid: %s != %s",
+			dev_fsid, fsid);
+		goto error_out;
+	}
+
+	/*
+	 * Hint to catch really bogus numbers, bitflips or so
+	 */
+	if (btrfs_super_num_devices(sb) > (1UL << 31)) {
+		error("suspicious number of devices: %llu",
+			btrfs_super_num_devices(sb));
+	}
+
+	if (btrfs_super_num_devices(sb) == 0) {
+		error("number of devices is 0");
+		goto error_out;
+	}
+
+	/*
+	 * Obvious sys_chunk_array corruptions, it must hold at least one key
+	 * and one chunk
+	 */
+	if (btrfs_super_sys_array_size(sb) > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE) {
+		error("system chunk array too big %u > %u",
+		      btrfs_super_sys_array_size(sb),
+		      BTRFS_SYSTEM_CHUNK_ARRAY_SIZE);
+		goto error_out;
+	}
+	if (btrfs_super_sys_array_size(sb) < sizeof(struct btrfs_disk_key)
+			+ sizeof(struct btrfs_chunk)) {
+		error("system chunk array too small %u < %zu",
+		      btrfs_super_sys_array_size(sb),
+		      sizeof(struct btrfs_disk_key) +
+		      sizeof(struct btrfs_chunk));
+		goto error_out;
+	}
+
+	return 0;
+
+error_out:
+	error("superblock checksum matches but it has invalid members");
+	return -EIO;
+}
+
+/*
+ * btrfs_read_dev_super - read a valid primary superblock from a block device
+ * @desc,@part:	file descriptor of the device
+ * @sb:		buffer where the superblock is going to be read in
+ *
+ * Unlike the btrfs-progs/kernel version, here we ony care about the first
+ * super block, thus it's much simpler.
+ */
+int btrfs_read_dev_super(struct blk_desc *desc, struct disk_partition *part,
+			 struct btrfs_super_block *sb)
+{
+	char tmp[BTRFS_SUPER_INFO_SIZE];
+	struct btrfs_super_block *buf = (struct btrfs_super_block *)tmp;
+	int ret;
+
+	ret = __btrfs_devread(desc, part, tmp, BTRFS_SUPER_INFO_SIZE,
+			      BTRFS_SUPER_INFO_OFFSET);
+	if (ret < BTRFS_SUPER_INFO_SIZE)
+		return -EIO;
+
+	if (btrfs_super_bytenr(buf) != BTRFS_SUPER_INFO_OFFSET)
+		return -EIO;
+
+	if (btrfs_check_super(buf))
+		return -EIO;
+
+	memcpy(sb, buf, BTRFS_SUPER_INFO_SIZE);
+	return 0;
+}
+
+int btrfs_read_superblock(void)
+{
+	ALLOC_CACHE_ALIGN_BUFFER(char, raw_sb, BTRFS_SUPER_INFO_SIZE);
+	struct btrfs_super_block *sb = (struct btrfs_super_block *) raw_sb;
+	int ret;
+
+
+	btrfs_info.sb.generation = 0;
+
+	ret = btrfs_read_dev_super(btrfs_blk_desc, btrfs_part_info, sb);
+	if (ret < 0) {
+		pr_debug("%s: No valid BTRFS superblock found!\n", __func__);
+		return ret;
+	}
+	btrfs_super_block_to_cpu(sb);
+	memcpy(&btrfs_info.sb, sb, sizeof(*sb));
+
+	if (btrfs_info.sb.num_devices != 1) {
+		printf("%s: Unsupported number of devices (%lli). This driver "
+		       "only supports filesystem on one device.\n", __func__,
+		       btrfs_info.sb.num_devices);
+		return -1;
+	}
+
+	pr_debug("Chosen superblock with generation = %llu\n",
+	      btrfs_info.sb.generation);
+
+	return 0;
+}