Btrfs-progs: enhance btrfs-image to restore image onto multiple disks

This adds a 'btrfs-image -m' option, which let us restore an image that
is built from a btrfs of multiple disks onto several disks altogether.

This aims to address the following case,
$ mkfs.btrfs -m raid0 sda sdb
$ btrfs-image sda image.file
$ btrfs-image -r image.file sdc
---------
so we can only restore metadata onto sdc, and another thing is we can
only mount sdc with degraded mode as we don't provide informations of
another disk.  And, it's built as RAID0 and we have only one disk,
so after mount sdc we'll get into readonly mode.

This is just annoying for people(like me) who're trying to restore image
but turn to find they cannot make it work.

So this'll make your life easier, just tap
$ btrfs-image -m image.file sdc sdd
---------
then you get everything about metadata done, the same offset with that of
the originals(of course, you need offer enough disk size, at least the disk
size of the original disks).

Besides, this also works with raid5 and raid6 metadata image.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 262 insertions, 51 deletions

diff --git a/btrfs-image.c b/btrfs-image.c
index ebd283e5..82aa4f39 100644
--- a/btrfs-image.c
+++ b/btrfs-image.c
@@ -35,6 +35,7 @@
 #include "utils.h"
 #include "version.h"
 #include "volumes.h"
+#include "extent_io.h"
 
 #define HEADER_MAGIC		0xbd5c25e27295668bULL
 #define MAX_PENDING_SIZE	(256 * 1024)
@@ -136,6 +137,9 @@ struct mdrestore_struct {
 	int done;
 	int error;
 	int old_restore;
+	int fixup_offset;
+	int multi_devices;
+	struct btrfs_fs_info *info;
 };
 
 static int search_for_chunk_blocks(struct mdrestore_struct *mdres,
@@ -1589,9 +1593,10 @@ static void *restore_worker(void *data)
 	u8 *outbuf;
 	int outfd;
 	int ret;
+	int compress_size = MAX_PENDING_SIZE * 4;
 
 	outfd = fileno(mdres->out);
-	buffer = malloc(MAX_PENDING_SIZE * 2);
+	buffer = malloc(compress_size);
 	if (!buffer) {
 		fprintf(stderr, "Error allocing buffer\n");
 		pthread_mutex_lock(&mdres->mutex);
@@ -1619,7 +1624,7 @@ static void *restore_worker(void *data)
 		pthread_mutex_unlock(&mdres->mutex);
 
 		if (mdres->compress_method == COMPRESS_ZLIB) {
-			size = MAX_PENDING_SIZE * 2;
+			size = compress_size; 
 			ret = uncompress(buffer, (unsigned long *)&size,
 					 async->buffer, async->bufsize);
 			if (ret != Z_OK) {
@@ -1633,44 +1638,60 @@ static void *restore_worker(void *data)
 			size = async->bufsize;
 		}
 
-		if (async->start == BTRFS_SUPER_INFO_OFFSET) {
-			if (mdres->old_restore) {
-				update_super_old(outbuf);
-			} else {
-				ret = update_super(outbuf);
+		if (!mdres->multi_devices) {
+			if (async->start == BTRFS_SUPER_INFO_OFFSET) {
+				if (mdres->old_restore) {
+					update_super_old(outbuf);
+				} else {
+					ret = update_super(outbuf);
+					if (ret)
+						err = ret;
+				}
+			} else if (!mdres->old_restore) {
+				ret = fixup_chunk_tree_block(mdres, async, outbuf, size);
 				if (ret)
 					err = ret;
 			}
-		} else if (!mdres->old_restore) {
-			ret = fixup_chunk_tree_block(mdres, async, outbuf, size);
-			if (ret)
-				err = ret;
-		}
-
-		while (size) {
-			u64 chunk_size = size;
-			bytenr = logical_to_physical(mdres,
-						     async->start + offset,
-						     &chunk_size);
-			ret = pwrite64(outfd, outbuf+offset, chunk_size,
-				       bytenr);
-			if (ret < chunk_size) {
-				if (ret < 0) {
-					fprintf(stderr, "Error writing to "
-						"device %d\n", errno);
-					err = errno;
-					break;
-				} else {
-					fprintf(stderr, "Short write\n");
-					err = -EIO;
-					break;
+		}
+
+		if (!mdres->fixup_offset) {
+			while (size) {
+				u64 chunk_size = size;
+				if (!mdres->multi_devices)
+					bytenr = logical_to_physical(mdres,
+								     async->start + offset,
+								     &chunk_size);
+				else
+					bytenr = async->start + offset;
+
+				ret = pwrite64(outfd, outbuf+offset, chunk_size,
+					       bytenr);
+				if (ret != chunk_size) {
+					if (ret < 0) {
+						fprintf(stderr, "Error writing to "
+							"device %d\n", errno);
+						err = errno;
+						break;
+					} else {
+						fprintf(stderr, "Short write\n");
+						err = -EIO;
+						break;
+					}
 				}
+				size -= chunk_size;
+				offset += chunk_size;
+			}
+		} else if (async->start != BTRFS_SUPER_INFO_OFFSET) {
+			ret = write_data_to_disk(mdres->info, outbuf, async->start, size, 0);
+			if (ret) {
+				printk("Error write data\n");
+				exit(1);
 			}
-			size -= chunk_size;
-			offset += chunk_size;
 		}
 
-		if (async->start == BTRFS_SUPER_INFO_OFFSET)
+
+		/* backup super blocks are already there at fixup_offset stage */
+		if (!mdres->multi_devices && async->start == BTRFS_SUPER_INFO_OFFSET)
 			write_backup_supers(outfd, outbuf);
 
 		pthread_mutex_lock(&mdres->mutex);
@@ -1714,7 +1735,8 @@ static void mdrestore_destroy(struct mdrestore_struct *mdres)
 
 static int mdrestore_init(struct mdrestore_struct *mdres,
 			  FILE *in, FILE *out, int old_restore,
-			  int num_threads)
+			  int num_threads, int fixup_offset,
+			  struct btrfs_fs_info *info, int multi_devices)
 {
 	int i, ret = 0;
 
@@ -1726,6 +1748,9 @@ static int mdrestore_init(struct mdrestore_struct *mdres,
 	mdres->out = out;
 	mdres->old_restore = old_restore;
 	mdres->chunk_tree.rb_node = NULL;
+	mdres->fixup_offset = fixup_offset;
+	mdres->info = info;
+	mdres->multi_devices = multi_devices;
 
 	if (!num_threads)
 		return 0;
@@ -2186,12 +2211,14 @@ static int build_chunk_tree(struct mdrestore_struct *mdres,
 	return search_for_chunk_blocks(mdres, chunk_root_bytenr, 0);
 }
 
-static int restore_metadump(const char *input, FILE *out, int old_restore,
-			    int num_threads)
+static int __restore_metadump(const char *input, FILE *out, int old_restore,
+			      int num_threads, int fixup_offset,
+			      const char *target, int multi_devices)
 {
 	struct meta_cluster *cluster = NULL;
 	struct meta_cluster_header *header;
 	struct mdrestore_struct mdrestore;
+	struct btrfs_fs_info *info = NULL;
 	u64 bytenr = 0;
 	FILE *in = NULL;
 	int ret = 0;
@@ -2206,26 +2233,36 @@ static int restore_metadump(const char *input, FILE *out, int old_restore,
 		}
 	}
 
+	/* NOTE: open with write mode */
+	if (fixup_offset) {
+		BUG_ON(!target);
+		info = open_ctree_fs_info_restore(target, 0, 0, 1, 1);
+		if (!info) {
+			fprintf(stderr, "%s: open ctree failed\n", __func__);
+			ret = -EIO;
+			goto failed_open;
+		}
+	}
+
 	cluster = malloc(BLOCK_SIZE);
 	if (!cluster) {
 		fprintf(stderr, "Error allocating cluster\n");
-		if (in != stdin)
-			fclose(in);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto failed_info;
 	}
 
-	ret = mdrestore_init(&mdrestore, in, out, old_restore, num_threads);
+	ret = mdrestore_init(&mdrestore, in, out, old_restore, num_threads,
+			     fixup_offset, info, multi_devices);
 	if (ret) {
 		fprintf(stderr, "Error initing mdrestore %d\n", ret);
-		if (in != stdin)
-			fclose(in);
-		free(cluster);
-		return ret;
+		goto failed_cluster;
 	}
 
-	ret = build_chunk_tree(&mdrestore, cluster);
-	if (ret)
-		goto out;
+	if (!multi_devices) {
+		ret = build_chunk_tree(&mdrestore, cluster);
+		if (ret)
+			goto out;
+	}
 
 	if (in != stdin && fseek(in, 0, SEEK_SET)) {
 		fprintf(stderr, "Error seeking %d\n", errno);
@@ -2259,12 +2296,123 @@ static int restore_metadump(const char *input, FILE *out, int old_restore,
 	}
 out:
 	mdrestore_destroy(&mdrestore);
+failed_cluster:
 	free(cluster);
+failed_info:
+	if (fixup_offset && info)
+		close_ctree(info->chunk_root);
+failed_open:
 	if (in != stdin)
 		fclose(in);
 	return ret;
 }
 
+static int restore_metadump(const char *input, FILE *out, int old_restore,
+			    int num_threads, int multi_devices)
+{
+	return __restore_metadump(input, out, old_restore, num_threads, 0, NULL,
+				  multi_devices);
+}
+
+static int fixup_metadump(const char *input, FILE *out, int num_threads,
+			  const char *target)
+{
+	return __restore_metadump(input, out, 0, num_threads, 1, target, 1);
+}
+
+static int update_disk_super_on_device(struct btrfs_fs_info *info,
+				       const char *other_dev, u64 cur_devid)
+{
+	struct btrfs_key key;
+	struct extent_buffer *leaf;
+	struct btrfs_path path;
+	struct btrfs_dev_item *dev_item;
+	struct btrfs_super_block *disk_super;
+	char dev_uuid[BTRFS_UUID_SIZE];
+	char fs_uuid[BTRFS_UUID_SIZE];
+	u64 devid, type, io_align, io_width;
+	u64 sector_size, total_bytes, bytes_used;
+	char *buf;
+	int fp;
+	int ret;
+
+	key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
+	key.type = BTRFS_DEV_ITEM_KEY;
+	key.offset = cur_devid;
+
+	btrfs_init_path(&path);
+	ret = btrfs_search_slot(NULL, info->chunk_root, &key, &path, 0, 0); 
+	if (ret) {
+		fprintf(stderr, "search key fails\n");
+		exit(1);
+	}
+
+	leaf = path.nodes[0];
+	dev_item = btrfs_item_ptr(leaf, path.slots[0],
+				  struct btrfs_dev_item);
+
+	devid = btrfs_device_id(leaf, dev_item);
+	if (devid != cur_devid) {
+		printk("devid %llu mismatch with %llu\n", devid, cur_devid);
+		exit(1);
+	}
+
+	type = btrfs_device_type(leaf, dev_item);
+	io_align = btrfs_device_io_align(leaf, dev_item);
+	io_width = btrfs_device_io_width(leaf, dev_item);
+	sector_size = btrfs_device_sector_size(leaf, dev_item);
+	total_bytes = btrfs_device_total_bytes(leaf, dev_item);
+	bytes_used = btrfs_device_bytes_used(leaf, dev_item);
+	read_extent_buffer(leaf, dev_uuid, (unsigned long)btrfs_device_uuid(dev_item), BTRFS_UUID_SIZE);
+	read_extent_buffer(leaf, fs_uuid, (unsigned long)btrfs_device_fsid(dev_item), BTRFS_UUID_SIZE);
+
+	btrfs_release_path(info->chunk_root, &path);
+
+	printk("update disk super on %s devid=%llu\n", other_dev, devid);
+
+	/* update other devices' super block */
+	fp = open(other_dev, O_CREAT | O_RDWR, 0600);
+	if (fp < 0) {
+		fprintf(stderr, "could not open %s\n", other_dev);
+		exit(1);
+	}
+
+	buf = malloc(BTRFS_SUPER_INFO_SIZE);
+	if (!buf) {
+		ret = -ENOMEM;
+		exit(1);
+	}
+
+	memcpy(buf, info->super_copy, BTRFS_SUPER_INFO_SIZE);
+
+	disk_super = (struct btrfs_super_block *)buf;
+	dev_item = &disk_super->dev_item;
+
+	btrfs_set_stack_device_type(dev_item, type);
+	btrfs_set_stack_device_id(dev_item, devid);
+	btrfs_set_stack_device_total_bytes(dev_item, total_bytes);
+	btrfs_set_stack_device_bytes_used(dev_item, bytes_used);
+	btrfs_set_stack_device_io_align(dev_item, io_align);
+	btrfs_set_stack_device_io_width(dev_item, io_width);
+	btrfs_set_stack_device_sector_size(dev_item, sector_size);
+	memcpy(dev_item->uuid, dev_uuid, BTRFS_UUID_SIZE);
+	memcpy(dev_item->fsid, fs_uuid, BTRFS_UUID_SIZE);
+	csum_block((u8 *)buf, BTRFS_SUPER_INFO_SIZE);
+
+	ret = pwrite64(fp, buf, BTRFS_SUPER_INFO_SIZE, BTRFS_SUPER_INFO_OFFSET);
+	if (ret != BTRFS_SUPER_INFO_SIZE) {
+		ret = -EIO;
+		goto out;
+	}
+
+	write_backup_supers(fp, (u8 *)buf);
+
+out:
+	free(buf);
+	close(fp);
+	return 0;
+}
+
 static void print_usage(void)
 {
 	fprintf(stderr, "usage: btrfs-image [options] source target\n");
@@ -2286,12 +2434,14 @@ int main(int argc, char *argv[])
 	int create = 1;
 	int old_restore = 0;
 	int walk_trees = 0;
+	int multi_devices = 0;
 	int ret;
 	int sanitize = 0;
+	int dev_cnt = 0;
 	FILE *out;
 
 	while (1) {
-		int c = getopt(argc, argv, "rc:t:osw");
+		int c = getopt(argc, argv, "rc:t:oswm");
 		if (c < 0)
 			break;
 		switch (c) {
@@ -2317,17 +2467,26 @@ int main(int argc, char *argv[])
 		case 'w':
 			walk_trees = 1;
 			break;
+		case 'm':
+			create = 0;
+			multi_devices = 1;
+			break;
 		default:
 			print_usage();
 		}
 	}
 
-	if (old_restore && create)
+	if ((old_restore) && create)
 		print_usage();
 
 	argc = argc - optind;
-	if (argc != 2)
+	dev_cnt = argc - 1;
+
+	if (multi_devices && dev_cnt < 2)
+		print_usage();
+	if (!multi_devices && dev_cnt != 1)
 		print_usage();
+
 	source = argv[optind];
 	target = argv[optind + 1];
 
@@ -2351,8 +2510,60 @@ int main(int argc, char *argv[])
 		ret = create_metadump(source, out, num_threads,
 				      compress_level, sanitize, walk_trees);
 	else
-		ret = restore_metadump(source, out, old_restore, 1);
+		ret = restore_metadump(source, out, old_restore, 1,
+				       multi_devices);
+	if (ret) {
+		printk("%s failed (%s)\n", (create) ? "create" : "restore",
+		       strerror(errno));
+		goto out;
+	}
+
+	 /* extended support for multiple devices */
+	if (!create && multi_devices) {
+		struct btrfs_fs_info *info;
+		u64 total_devs;
+		int i;
+
+		info = open_ctree_fs_info_restore(target, 0, 0, 0, 1);
+		if (!info) {
+			int e = errno;
+			fprintf(stderr, "unable to open %s error = %s\n",
+				target, strerror(e));
+			return 1;
+		}
+
+		total_devs = btrfs_super_num_devices(info->super_copy);
+		if (total_devs != dev_cnt) {
+			printk("it needs %llu devices but has only %d\n",
+				total_devs, dev_cnt);
+			close_ctree(info->chunk_root);
+			goto out;
+		}
 
+		/* update super block on other disks */
+		for (i = 2; i <= dev_cnt; i++) {
+			ret = update_disk_super_on_device(info,
+					argv[optind + i], (u64)i);
+			if (ret) {
+				printk("update disk super failed devid=%d (error=%d)\n",
+					i, ret);
+				close_ctree(info->chunk_root);
+				exit(1);
+			}
+		}
+
+		close_ctree(info->chunk_root);
+
+		/* fix metadata block to map correct chunk */
+		ret = fixup_metadump(source, out, 1, target);
+		if (ret) {
+			fprintf(stderr, "fix metadump failed (error=%d)\n",
+				ret);
+			exit(1);
+		}
+	}
+
+out:
 	if (out == stdout)
 		fflush(out);
 	else