btrfs-progs: Utilities for dumping and rolling back to oldest super on filesystem

.gitignore

@@ -3,12 +3,16 @@
 version.h
 man/*.gz
 btrfs
+btrfs-corrupt-block
 btrfs-debug-tree
+btrfs-dump-super
 btrfs-map-logical
+btrfs-select-super
 btrfs-show
 btrfs-vol
 btrfsck
 btrfsctl
+calc-size
 find-root
 mkfs.btrfs
 repair

Makefile

@@ -17,7 +17,8 @@ LIBS=-luuid
 RESTORE_LIBS=-lz
 
 progs = btrfsctl mkfs.btrfs btrfs-debug-tree btrfs-show btrfs-vol btrfsck \
-	btrfs btrfs-map-logical restore find-root calc-size btrfs-corrupt-block
+	btrfs btrfs-map-logical restore find-root calc-size btrfs-corrupt-block \
+	btrfs-dump-super
 
 # make C=1 to enable sparse
 ifdef C
@@ -73,6 +74,9 @@ btrfs-zero-log: $(objects) btrfs-zero-log.o
 btrfs-select-super: $(objects) btrfs-select-super.o
 	$(CC) $(CFLAGS) -o btrfs-select-super $(objects) btrfs-select-super.o $(LDFLAGS) $(LIBS)
 
+btrfs-dump-super: $(objects) btrfs-dump-super.o
+	$(CC) $(CFLAGS) -o btrfs-dump-super $(objects) btrfs-dump-super.o $(LDFLAGS) $(LIBS)
+
 btrfstune: $(objects) btrfstune.o
 	$(CC) $(CFLAGS) -o btrfstune $(objects) btrfstune.o $(LDFLAGS) $(LIBS)
 
@@ -105,7 +109,8 @@ install-man:
 
 clean :
 	rm -f $(progs) cscope.out *.o .*.d btrfs-convert btrfs-image btrfs-select-super \
-	      btrfs-zero-log btrfstune dir-test ioctl-test quick-test version.h
+	      btrfs-dump-super btrfs-zero-log btrfstune dir-test ioctl-test quick-test \
+	      version.h
 	cd man; make clean
 
 install: $(progs) install-man

btrfs-dump-super.c

@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2011 Google.  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.
+ */
+
+#define _XOPEN_SOURCE 500
+#define _GNU_SOURCE 1
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include "kerncompat.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "version.h"
+
+static void print_usage(void)
+{
+	fprintf(stderr, "usage: btrfs-dump-super dev\n");
+	fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
+	exit(1);
+}
+
+static int read_block(const char* filename,  u64 bytenr, struct btrfs_super_block* sb) {
+	int fd = open(filename, O_RDONLY, 0600);
+	int block_size = sizeof(struct btrfs_super_block);
+	int bytes_read = 0;
+
+	if (fd < 0) {
+		fprintf(stderr, "Could not open %s\n", filename);
+		return -1;
+	}
+
+	bytes_read = pread(fd, sb, block_size, bytenr);
+	if (bytes_read < block_size) {
+		fprintf(stderr, "Only read %d bytes of %d.\n", bytes_read, block_size);
+	}
+
+	close(fd);
+	return bytes_read;
+}
+
+int main(int ac, char **av)
+{
+	int i;
+
+	if (ac != 2)
+		print_usage();
+
+	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+		u64 bytenr = btrfs_sb_offset(i);
+		int fd;
+		struct btrfs_super_block sb;
+		int block_size = sizeof(struct btrfs_super_block);
+		char filename[1024];
+		int bytes_read = read_block(av[optind], bytenr, &sb);
+		if (bytes_read < block_size)
+			continue;
+
+		sprintf(filename, "/tmp/block.%s.%llu",
+			strrchr(av[optind], '/') + 1, bytenr);
+		fd = open(filename, O_CREAT|O_WRONLY, 0644);
+		if (block_size != pwrite(fd, &sb, block_size, 0)) {
+			fprintf(stderr, "Failed to dump superblock %d", i);
+			continue;
+		}
+		fprintf(stderr, "Dumped superblock %s:%d, gen %llu to %s.\n",
+			av[optind], i, sb.generation, filename);
+		close(fd);
+	}
+
+	return 0;
+}

btrfs-select-super.c

@@ -34,7 +34,9 @@
 
 static void print_usage(void)
 {
-	fprintf(stderr, "usage: btrfs-select-super -s number dev\n");
+	fprintf(stderr, "usage: btrfs-select-super [-c] [-e] -s number dev\n");
+	fprintf(stderr, "       -c Commit changes to disk [IRREVERSIBLE]\n");
+	fprintf(stderr, "       -e Use the earliest super found, may help recover transid verify problems\n");
 	fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
 	exit(1);
 }
@@ -45,10 +47,13 @@ int main(int ac, char **av)
 	int ret;
 	int num;
 	u64 bytenr = 0;
+	int commit = 0;
+	int use_lowest_bdev = 0;
+	int fp;
 
 	while(1) {
 		int c;
-		c = getopt(ac, av, "s:");
+		c = getopt(ac, av, "s:ce");
 		if (c < 0)
 			break;
 		switch(c) {
@@ -58,6 +63,12 @@ int main(int ac, char **av)
 				printf("using SB copy %d, bytenr %llu\n", num,
 				       (unsigned long long)bytenr);
 				break;
+			case 'c':
+				commit = 1;
+				break;
+			case 'e':
+				use_earliest_bdev = 1;
+				break;
 			default:
 				print_usage();
 		}
@@ -74,22 +85,33 @@ int main(int ac, char **av)
 
 	radix_tree_init();
 
-	if((ret = check_mounted(av[optind])) < 0) {
+	if ((ret = check_mounted(av[optind])) < 0) {
 		fprintf(stderr, "Could not check mount status: %s\n", strerror(-ret));
 		return ret;
-	} else if(ret) {
+	} else if (ret) {
 		fprintf(stderr, "%s is currently mounted. Aborting.\n", av[optind]);
 		return -EBUSY;
 	}
 
-	root = open_ctree(av[optind], bytenr, 1);
+	fp = open(av[optind], O_CREAT|O_RDRW, 0600);
+	if (fp < 0) {
+		fprintf(stderr, "Could not open %s\n", av[optind]);
+		return 1;
+	}
+	root = open_ctree_fd(fp, av[optind], bytenr, 1, use_earliest_bdev);
 
 	if (root == NULL)
 		return 1;
 
-	/* make the super writing code think we've read the first super */
-	root->fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
-	ret = write_all_supers(root);
+	fprintf(stderr, "Found superblock with generation %llu.\n", root->fs_info->super_copy.generation);
+
+	if (commit) {
+		fprintf(stderr, "Committing...\n");
+
+		/* make the super writing code think we've read the first super */
+		root->fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
+		ret = write_all_supers(root);
+	}
 
 	/* we don't close the ctree or anything, because we don't want a real
 	 * transaction commit.  We just want the super copy we pulled off the

convert.c

@@ -2386,7 +2386,7 @@ int do_convert(const char *devname, int datacsum, int packing, int noxattr)
 		fprintf(stderr, "unable to update system chunk\n");
 		goto fail;
 	}
-	root = open_ctree_fd(fd, devname, super_bytenr, O_RDWR);
+	root = open_ctree_fd(fd, devname, super_bytenr, O_RDWR, 0);
 	if (!root) {
 		fprintf(stderr, "unable to open ctree\n");
 		goto fail;
@@ -2447,7 +2447,7 @@ int do_convert(const char *devname, int datacsum, int packing, int noxattr)
 		goto fail;
 	}
 
-	root = open_ctree_fd(fd, devname, 0, O_RDWR);
+	root = open_ctree_fd(fd, devname, 0, O_RDWR, 0);
 	if (!root) {
 		fprintf(stderr, "unable to open ctree\n");
 		goto fail;
@@ -2546,7 +2546,7 @@ int do_rollback(const char *devname, int force)
 		fprintf(stderr, "unable to open %s\n", devname);
 		goto fail;
 	}
-	root = open_ctree_fd(fd, devname, 0, O_RDWR);
+	root = open_ctree_fd(fd, devname, 0, O_RDWR, 0);
 	if (!root) {
 		fprintf(stderr, "unable to open ctree\n");
 		goto fail;

disk-io.c

@@ -580,7 +580,7 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
 		return fs_info->dev_root;
 	if (location->objectid == BTRFS_CSUM_TREE_OBJECTID)
 		return fs_info->csum_root;
-	
+
 	BUG_ON(location->objectid == BTRFS_TREE_RELOC_OBJECTID ||
 	       location->offset != (u64)-1);
 
@@ -602,7 +602,8 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
 }
 
 struct btrfs_root *__open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
-				   u64 root_tree_bytenr, int writes)
+				   u64 root_tree_bytenr, int writes,
+				   int use_earliest_bdev)
 {
 	u32 sectorsize;
 	u32 nodesize;
@@ -677,8 +678,14 @@ struct btrfs_root *__open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
 
 	fs_info->super_bytenr = sb_bytenr;
 	disk_super = &fs_info->super_copy;
-	ret = btrfs_read_dev_super(fs_devices->latest_bdev,
-				   disk_super, sb_bytenr);
+	if (use_earliest_bdev) {
+		ret = btrfs_read_dev_super(fs_devices->earliest_bdev,
+					   disk_super, sb_bytenr);
+	} else {
+		ret = btrfs_read_dev_super(fs_devices->latest_bdev,
+					   disk_super, sb_bytenr);
+	}
+
 	if (ret) {
 		printk("No valid btrfs found\n");
 		goto out_devices;
@@ -847,7 +854,7 @@ struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr, int writes)
 		fprintf (stderr, "Could not open %s\n", filename);
 		return NULL;
 	}
-	root = __open_ctree_fd(fp, filename, sb_bytenr, 0, writes);
+	root = __open_ctree_fd(fp, filename, sb_bytenr, 0, writes, 0);
 	close(fp);
 
 	return root;
@@ -864,16 +871,16 @@ struct btrfs_root *open_ctree_recovery(const char *filename, u64 sb_bytenr,
 		fprintf (stderr, "Could not open %s\n", filename);
 		return NULL;
 	}
-	root = __open_ctree_fd(fp, filename, sb_bytenr, root_tree_bytenr, 0);
+	root = __open_ctree_fd(fp, filename, sb_bytenr, root_tree_bytenr, 0, 0);
 	close(fp);
 
 	return root;
 }
 
 struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
-				 int writes)
+				 int writes, int use_earliest_bdev)
 {
-	return __open_ctree_fd(fp, path, sb_bytenr, 0, writes);
+	return __open_ctree_fd(fp, path, sb_bytenr, 0, writes, use_earliest_bdev);
 }
 
 int btrfs_read_dev_super(int fd, struct btrfs_super_block *sb, u64 sb_bytenr)

disk-io.h

@@ -45,7 +45,7 @@ int clean_tree_block(struct btrfs_trans_handle *trans,
 		     struct btrfs_root *root, struct extent_buffer *buf);
 struct btrfs_root *open_ctree(const char *filename, u64 sb_bytenr, int writes);
 struct btrfs_root *open_ctree_fd(int fp, const char *path, u64 sb_bytenr,
-				 int writes);
+				 int writes, int use_earliest_bdev);
 struct btrfs_root *open_ctree_recovery(const char *filename, u64 sb_bytenr,
 				       u64 root_tree_bytenr);
 int close_ctree(struct btrfs_root *root);

volumes.c

@@ -99,6 +99,8 @@ static int device_list_add(const char *path,
 		memcpy(fs_devices->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
 		fs_devices->latest_devid = devid;
 		fs_devices->latest_trans = found_transid;
+		fs_devices->earliest_devid = devid;
+		fs_devices->earliest_trans = found_transid;
 		fs_devices->lowest_devid = (u64)-1;
 		device = NULL;
 	} else {
@@ -133,8 +135,11 @@ static int device_list_add(const char *path,
 	if (found_transid > fs_devices->latest_trans) {
 		fs_devices->latest_devid = devid;
 		fs_devices->latest_trans = found_transid;
+	} else if (found_transid < fs_devices->earliest_trans) {
+		fs_devices->earliest_devid = devid;
+		fs_devices->earliest_trans = found_transid;
 	}
-	if (fs_devices->lowest_devid > devid) {
+	if (devid < fs_devices->lowest_devid) {
 		fs_devices->lowest_devid = devid;
 	}
 	*fs_devices_ret = fs_devices;
@@ -183,6 +188,8 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, int flags)
 
 		if (device->devid == fs_devices->latest_devid)
 			fs_devices->latest_bdev = fd;
+		if (device->devid == fs_devices->earliest_devid)
+			fs_devices->earliest_bdev = fd;
 		if (device->devid == fs_devices->lowest_devid)
 			fs_devices->lowest_bdev = fd;
 		device->fd = fd;

volumes.h

@@ -64,11 +64,15 @@ struct btrfs_device {
 struct btrfs_fs_devices {
 	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
 
-	/* the device with this id has the most recent coyp of the super */
+	/* the device with this id has the most recent copy of the super */
 	u64 latest_devid;
 	u64 latest_trans;
+	/* the device with this id has the least recent copy of the super */
+	u64 earliest_devid;
+	u64 earliest_trans;
 	u64 lowest_devid;
 	int latest_bdev;
+	int earliest_bdev;
 	int lowest_bdev;
 	struct list_head devices;
 	struct list_head list;