[15/18] btrfs-progs: NEW: btrfs-raw

Commit Message

[e-mail] Dec. 10, 2014, 8:51 p.m. UTC

From: Martin Wilck <[e-mail]>

This program can be used to dump a meta data block, fix it e.g.
using a hex editor, and write it back to disk, adapting the check
sum.

Signed-off-by: Martin Wilck <[e-mail]>
---
 Makefile    |    2 +-
 btrfs-raw.c |  143 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 144 insertions(+), 1 deletions(-)
 create mode 100644 btrfs-raw.c

Patch

diff --git a/Makefile b/Makefile
index 4cae30c..fe65867 100644
--- a/Makefile
+++ b/Makefile
@@ -46,7 +46,7 @@  endif
 
 MAKEOPTS = --no-print-directory Q=$(Q)
 
-progs = mkfs.btrfs btrfs-debug-tree btrfsck \
+progs = mkfs.btrfs btrfs-debug-tree btrfs-raw btrfsck \
 	btrfs btrfs-map-logical btrfs-image btrfs-zero-log btrfs-convert \
 	btrfs-find-root btrfstune btrfs-show-super
 
diff --git a/btrfs-raw.c b/btrfs-raw.c
new file mode 100644
index 0000000..1dfeed9
--- /dev/null
+++ b/btrfs-raw.c
@@ -0,0 +1,143 @@ 
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "kerncompat.h"
+#include "radix-tree.h"
+#include "ctree.h"
+#include "utils.h"
+#include "disk-io.h"
+
+static int print_usage(void)
+{
+	fprintf(stderr, "usage: btrfs-raw [ -r block|-w block] device\n");
+	exit(1);
+}
+
+static int read_block(struct btrfs_root *root, u64 block_nr,
+		      struct extent_buffer **eb)
+{
+	struct extent_buffer *leaf;
+	leaf = read_tree_block(root,
+			       block_nr,
+			       root->leafsize, 0);
+	
+	if (leaf && btrfs_header_level(leaf) != 0) {
+		free_extent_buffer(leaf);
+		leaf = NULL;
+	}
+	
+	if (!leaf) {
+		leaf = read_tree_block(root,
+				       block_nr,
+				       root->nodesize, 0);
+	}
+	if (!leaf) {
+		fprintf(stderr, "failed to read %llu\n",
+			(unsigned long long)block_nr);
+		return -1;
+	}
+
+	*eb = leaf;
+	return btrfs_is_leaf(leaf) ? root->leafsize : root->nodesize;
+}
+
+int main(int ac, char **av)
+{
+	struct btrfs_root *root;
+	struct btrfs_fs_info *info;
+	struct extent_buffer *eb = NULL;
+	struct btrfs_trans_handle *trans = NULL;
+	u64 block = ~0ULL;
+	int len;
+	enum btrfs_open_ctree_flags flags = OPEN_CTREE_PARTIAL;
+	radix_tree_init();
+
+	while(1) {
+		int c;
+		c = getopt(ac, av, "r:w:");
+		if (c < 0)
+			break;
+		switch(c) {
+			case 'r':
+				block = arg_strtou64(optarg);
+				break;
+			case 'w':
+				flags |= OPEN_CTREE_WRITES;
+				block = arg_strtou64(optarg);
+				break;
+			default:
+				print_usage();
+		}
+	}
+	set_argv0(av);
+	ac = ac - optind;
+	if (check_argc_exact(ac, 1) || block == ~0ULL)
+		print_usage();
+
+	info = open_ctree_fs_info(av[optind], 0, 0, flags);
+	if (!info) {
+		fprintf(stderr, "unable to open %s\n", av[optind]);
+		exit(1);
+	}
+
+	root = info->fs_root;
+	if (!root) {
+		fprintf(stderr, "unable to open %s\n", av[optind]);
+		exit(1);
+	}
+
+	len = read_block(root, block, &eb);
+	if (eb->len != len) {
+		fprintf(stderr, "length mismatch: %u %d\n", eb->len, len);
+		return 1;
+	}
+
+	if (flags & OPEN_CTREE_WRITES) {
+		char buf[4];
+		int ret;
+		fprintf(stderr, "*** THIS MAY CORRUPT YOUR FILE SYSTEM ***\n");
+		fprintf(stderr, "*** Do you want to write logical block %llu "
+			"on device %s ?\n", block, av[optind]);
+		fprintf(stderr, "*** Type upper case \"yes\" to continue: ");
+		memset(buf, 0, 4);
+		ret = read(fileno(stderr), buf, 3);
+		if (strcmp(buf, "YES")) {
+			fprintf(stderr, "*** Aborted.\n");
+			goto out;
+		}
+		fprintf(stderr, "*** Writing block ... ");
+		if (fread(&eb->data, len, 1, stdin) < 1) {
+			fprintf(stderr, "failed to read %d bytes\n", len);
+			return 1;
+		}
+		btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
+		csum_tree_block(root, eb, 0);
+		if (write_and_map_eb(trans, root, eb))
+			fprintf(stderr, "error writing block %llu\n", block);
+		else
+			fprintf(stderr, " done.\n");
+	} else if (fwrite(&eb->data, len, 1, stdout) < 1)
+		fprintf(stderr, "failed to write %d bytes\n", len);
+
+out:
+	free_extent_buffer(eb);
+	return close_ctree(root);
+}