Btrfs-progs: add an option to btrfs-image to walk the trees

When working with a user with a broken file system I noticed I wasn't able to
read some of the blocks properly from the restored image.  This is because his
extent tree was corrupt and was missing references to some of the blocks, which
means they weren't copied into the image when he generated it.  So add a -w
option which will walk all of the trees manually and copy them into the image.
This way we can run fsck against a complete file system image and fix any bugs
in fsck.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

2 files changed, 103 insertions, 65 deletions

diff --git a/btrfs-image.c b/btrfs-image.c
index 9a0a2493..188291ca 100644
--- a/btrfs-image.c
+++ b/btrfs-image.c
@@ -605,9 +605,8 @@ static int is_tree_block(struct btrfs_root *extent_root,
 }
 #endif
 
-static int copy_log_blocks(struct btrfs_root *root, struct extent_buffer *eb,
-			   struct metadump_struct *metadump,
-			   int log_root_tree)
+static int copy_tree_blocks(struct btrfs_root *root, struct extent_buffer *eb,
+			    struct metadump_struct *metadump, int root_tree)
 {
 	struct extent_buffer *tmp;
 	struct btrfs_root_item *ri;
@@ -624,7 +623,7 @@ static int copy_log_blocks(struct btrfs_root *root, struct extent_buffer *eb,
 		return ret;
 	}
 
-	if (btrfs_header_level(eb) == 0 && !log_root_tree)
+	if (btrfs_header_level(eb) == 0 && !root_tree)
 		return 0;
 
 	level = btrfs_header_level(eb);
@@ -642,7 +641,7 @@ static int copy_log_blocks(struct btrfs_root *root, struct extent_buffer *eb,
 					"Error reading log root block\n");
 				return -EIO;
 			}
-			ret = copy_log_blocks(root, tmp, metadump, 0);
+			ret = copy_tree_blocks(root, tmp, metadump, 0);
 			free_extent_buffer(tmp);
 			if (ret)
 				return ret;
@@ -653,8 +652,7 @@ static int copy_log_blocks(struct btrfs_root *root, struct extent_buffer *eb,
 				fprintf(stderr, "Error reading log block\n");
 				return -EIO;
 			}
-			ret = copy_log_blocks(root, tmp, metadump,
-					      log_root_tree);
+			ret = copy_tree_blocks(root, tmp, metadump, root_tree);
 			free_extent_buffer(tmp);
 			if (ret)
 				return ret;
@@ -679,8 +677,8 @@ static int copy_log_trees(struct btrfs_root *root,
 		return -EIO;
 	}
 
-	return copy_log_blocks(root, root->fs_info->log_root_tree->node,
-			       metadump, 1);
+	return copy_tree_blocks(root, root->fs_info->log_root_tree->node,
+				metadump, 1);
 }
 
 static int copy_space_cache(struct btrfs_root *root,
@@ -749,51 +747,18 @@ static int copy_space_cache(struct btrfs_root *root,
 	return 0;
 }
 
-static int create_metadump(const char *input, FILE *out, int num_threads,
-			   int compress_level)
+static int copy_from_extent_tree(struct metadump_struct *metadump,
+				 struct btrfs_path *path)
 {
-	struct btrfs_root *root;
 	struct btrfs_root *extent_root;
-	struct btrfs_path *path = NULL;
 	struct extent_buffer *leaf;
 	struct btrfs_extent_item *ei;
 	struct btrfs_key key;
-	struct metadump_struct metadump;
 	u64 bytenr;
 	u64 num_bytes;
 	int ret;
-	int err = 0;
-
-	root = open_ctree(input, 0, 0);
-	if (!root) {
-		fprintf(stderr, "Open ctree failed\n");
-		return -EIO;
-	}
-
-	BUG_ON(root->nodesize != root->leafsize);
-
-	ret = metadump_init(&metadump, root, out, num_threads,
-			    compress_level);
-	if (ret) {
-		fprintf(stderr, "Error initing metadump %d\n", ret);
-		close_ctree(root);
-		return ret;
-	}
-
-	ret = add_extent(BTRFS_SUPER_INFO_OFFSET, 4096, &metadump, 0);
-	if (ret) {
-		fprintf(stderr, "Error adding metadata %d\n", ret);
-		err = ret;
-		goto out;
-	}
 
-	extent_root = root->fs_info->extent_root;
-	path = btrfs_alloc_path();
-	if (!path) {
-		fprintf(stderr, "Out of memory allocing path\n");
-		err = -ENOMEM;
-		goto out;
-	}
+	extent_root = metadump->root->fs_info->extent_root;
 	bytenr = BTRFS_SUPER_INFO_OFFSET + 4096;
 	key.objectid = bytenr;
 	key.type = BTRFS_EXTENT_ITEM_KEY;
@@ -802,9 +767,9 @@ static int create_metadump(const char *input, FILE *out, int num_threads,
 	ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
 	if (ret < 0) {
 		fprintf(stderr, "Error searching extent root %d\n", ret);
-		err = ret;
-		goto out;
+		return ret;
 	}
+	ret = 0;
 
 	while (1) {
 		leaf = path->nodes[0];
@@ -813,11 +778,12 @@ static int create_metadump(const char *input, FILE *out, int num_threads,
 			if (ret < 0) {
 				fprintf(stderr, "Error going to next leaf %d"
 					"\n", ret);
-				err = ret;
-				goto out;
+				break;
 			}
-			if (ret > 0)
+			if (ret > 0) {
+				ret = 0;
 				break;
+			}
 			leaf = path->nodes[0];
 		}
 
@@ -833,20 +799,19 @@ static int create_metadump(const char *input, FILE *out, int num_threads,
 		if (key.type == BTRFS_METADATA_ITEM_KEY)
 			num_bytes = key.offset;
 		else
-			num_bytes = root->leafsize;
+			num_bytes = extent_root->leafsize;
 
 		if (btrfs_item_size_nr(leaf, path->slots[0]) > sizeof(*ei)) {
 			ei = btrfs_item_ptr(leaf, path->slots[0],
 					    struct btrfs_extent_item);
 			if (btrfs_extent_flags(leaf, ei) &
 			    BTRFS_EXTENT_FLAG_TREE_BLOCK) {
-				ret = add_extent(bytenr, num_bytes, &metadump,
+				ret = add_extent(bytenr, num_bytes, metadump,
 						 0);
 				if (ret) {
 					fprintf(stderr, "Error adding block "
 						"%d\n", ret);
-					err = ret;
-					goto out;
+					break;
 				}
 			}
 		} else {
@@ -855,31 +820,94 @@ static int create_metadump(const char *input, FILE *out, int num_threads,
 			if (ret < 0) {
 				fprintf(stderr, "Error checking tree block "
 					"%d\n", ret);
-				err = ret;
-				goto out;
+				break;
 			}
 
 			if (ret) {
-				ret = add_extent(bytenr, num_bytes, &metadump,
+				ret = add_extent(bytenr, num_bytes, metadump,
 						 0);
 				if (ret) {
 					fprintf(stderr, "Error adding block "
 						"%d\n", ret);
-					err = ret;
-					goto out;
+					break;
 				}
 			}
+			ret = 0;
 #else
 			fprintf(stderr, "Either extent tree corruption or "
 				"you haven't built with V0 support\n");
-			err = -EIO;
-			goto out;
+			ret = -EIO;
+			break;
 #endif
 		}
 		bytenr += num_bytes;
 	}
 
-	btrfs_release_path(root, path);
+	btrfs_release_path(extent_root, path);
+
+	return ret;
+}
+
+static int create_metadump(const char *input, FILE *out, int num_threads,
+			   int compress_level, int walk_trees)
+{
+	struct btrfs_root *root;
+	struct btrfs_path *path = NULL;
+	struct metadump_struct metadump;
+	int ret;
+	int err = 0;
+
+	root = open_ctree(input, 0, 0);
+	if (!root) {
+		fprintf(stderr, "Open ctree failed\n");
+		return -EIO;
+	}
+
+	BUG_ON(root->nodesize != root->leafsize);
+
+	ret = metadump_init(&metadump, root, out, num_threads,
+			    compress_level);
+	if (ret) {
+		fprintf(stderr, "Error initing metadump %d\n", ret);
+		close_ctree(root);
+		return ret;
+	}
+
+	ret = add_extent(BTRFS_SUPER_INFO_OFFSET, 4096, &metadump, 0);
+	if (ret) {
+		fprintf(stderr, "Error adding metadata %d\n", ret);
+		err = ret;
+		goto out;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		fprintf(stderr, "Out of memory allocing path\n");
+		err = -ENOMEM;
+		goto out;
+	}
+
+	if (walk_trees) {
+		ret = copy_tree_blocks(root, root->fs_info->chunk_root->node,
+				       &metadump, 1);
+		if (ret) {
+			err = ret;
+			goto out;
+		}
+
+		ret = copy_tree_blocks(root, root->fs_info->tree_root->node,
+				       &metadump, 1);
+		if (ret) {
+			err = ret;
+			goto out;
+		}
+	} else {
+		ret = copy_from_extent_tree(&metadump, path);
+		if (ret) {
+			err = ret;
+			goto out;
+		}
+	}
 
 	ret = copy_log_trees(root, &metadump, path);
 	if (ret) {
@@ -892,7 +920,7 @@ out:
 	ret = flush_pending(&metadump, 1);
 	if (ret) {
 		if (!err)
-			ret = err;
+			err = ret;
 		fprintf(stderr, "Error flushing pending %d\n", ret);
 	}
 
@@ -1498,6 +1526,7 @@ static void print_usage(void)
 	fprintf(stderr, "\t-c value\tcompression level (0 ~ 9)\n");
 	fprintf(stderr, "\t-t value\tnumber of threads (1 ~ 32)\n");
 	fprintf(stderr, "\t-o      \tdon't mess with the chunk tree when restoring\n");
+	fprintf(stderr, "\t-w      \twalk all trees instead of using extent tree, do this if your extent tree is broken\n");
 	exit(1);
 }
 
@@ -1509,11 +1538,12 @@ int main(int argc, char *argv[])
 	int compress_level = 0;
 	int create = 1;
 	int old_restore = 0;
+	int walk_trees = 0;
 	int ret;
 	FILE *out;
 
 	while (1) {
-		int c = getopt(argc, argv, "rc:t:o");
+		int c = getopt(argc, argv, "rc:t:ow");
 		if (c < 0)
 			break;
 		switch (c) {
@@ -1533,6 +1563,9 @@ int main(int argc, char *argv[])
 		case 'o':
 			old_restore = 1;
 			break;
+		case 'w':
+			walk_trees = 1;
+			break;
 		default:
 			print_usage();
 		}
@@ -1565,7 +1598,7 @@ int main(int argc, char *argv[])
 
 	if (create)
 		ret = create_metadump(source, out, num_threads,
-				      compress_level);
+				      compress_level, walk_trees);
 	else
 		ret = restore_metadump(source, out, old_restore, 1);
 
diff --git a/man/btrfs-image.8.in b/man/btrfs-image.8.in
index b738f672..7e0e3b0b 100644
--- a/man/btrfs-image.8.in
+++ b/man/btrfs-image.8.in
@@ -28,6 +28,11 @@ number of threads (1 ~ 32) to be used to process the image dump or restore.
 \fB\-o\fP
 use the old restore method, this does not fixup the chunk tree so the restored
 file system will not be able to be mounted.
+.TP
+\fB\-w\fP
+Walk all the trees manually and copy any blocks that are referenced. Use this
+option if your extent tree is corrupted to make sure that all of the metadata is
+captured.
 .SH AVAILABILITY
 .B btrfs-image
 is part of btrfs-progs. Btrfs is currently under heavy development,