File 0134-Btrfs-progs-give-restore-a-list-roots-option.patch of Package btrfsprogs

From 9bb7aa76e43f4942f5fa398bf00778067859f66c Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@redhat.com>
Date: Fri, 9 Dec 2011 14:09:18 -0500
Subject: [PATCH 35/35] Btrfs-progs: give restore a list roots option

Since restore has the ability to open really really screwed up file systems, add
a list roots option to it so we can still get the contents of the tree root on a
horribly broken fs.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
---
 restore.c |   95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 88 insertions(+), 7 deletions(-)

diff --git a/restore.c b/restore.c
index 398c49a..95daef2 100644
--- a/restore.c
+++ b/restore.c
@@ -773,11 +773,71 @@ next:
 
 static void usage()
 {
-	fprintf(stderr, "Usage: restore [-svioc] [-t disk offset] "
+	fprintf(stderr, "Usage: restore [-sviocl] [-t disk offset] "
 		"[-m regex] <device> <directory>\n");
 }
 
-static struct btrfs_root *open_fs(const char *dev, u64 root_location, int super_mirror)
+static int do_list_roots(struct btrfs_root *root)
+{
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	struct btrfs_disk_key disk_key;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_root_item ri;
+	unsigned long offset;
+	int slot;
+	int ret;
+
+	root = root->fs_info->tree_root;
+	path = btrfs_alloc_path();
+	if (!path) {
+		fprintf(stderr, "Failed to alloc path\n");
+		return -1;
+	}
+
+	key.offset = 0;
+	key.objectid = 0;
+	key.type = BTRFS_ROOT_ITEM_KEY;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to do search %d\n", ret);
+		btrfs_free_path(path);
+		return -1;
+	}
+
+	while (1) {
+		leaf = path->nodes[0];
+		slot = path->slots[0];
+		if (slot >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret)
+				break;
+			leaf = path->nodes[0];
+			slot = path->slots[0];
+		}
+		btrfs_item_key(leaf, &disk_key, slot);
+		btrfs_disk_key_to_cpu(&found_key, &disk_key);
+		if (btrfs_key_type(&found_key) != BTRFS_ROOT_ITEM_KEY) {
+			path->slots[0]++;
+			continue;
+		}
+
+		offset = btrfs_item_ptr_offset(leaf, slot);
+		read_extent_buffer(leaf, &ri, offset, sizeof(ri));
+		printf(" tree ");
+		btrfs_print_key(&disk_key);
+		printf(" %Lu level %d\n", btrfs_root_bytenr(&ri),
+		       btrfs_root_level(&ri));
+		path->slots[0]++;
+	}
+	btrfs_free_path(path);
+
+	return 0;
+}
+
+static struct btrfs_root *open_fs(const char *dev, u64 root_location, int super_mirror, int list_roots)
 {
 	struct btrfs_key key;
 	struct btrfs_root *root;
@@ -791,7 +851,7 @@ static struct btrfs_root *open_fs(const char *dev, u64 root_location, int super_
 		bytenr = btrfs_sb_offset(i);
 		root = open_ctree_recovery(dev, bytenr, root_location);
 		if (root)
-			return root;
+			goto out;
 		fprintf(stderr, "Could not open root, trying backup super\n");
 	}
 
@@ -826,16 +886,27 @@ static struct btrfs_root *open_fs(const char *dev, u64 root_location, int super_
 		return NULL;
 	}
 
+	if (list_roots)
+		goto out;
+
 	key.objectid = BTRFS_FS_TREE_OBJECTID;
 	key.type = BTRFS_ROOT_ITEM_KEY;
 	key.offset = (u64)-1;
 
 	root->fs_info->fs_root = btrfs_read_fs_root(root->fs_info, &key);
 	if (IS_ERR(root->fs_info->fs_root)) {
-		fprintf(stderr, "Couldn't read fs_root: %d\n", PTR_ERR(root));
+		fprintf(stderr, "Couldn't read fs_root: %ld\n", PTR_ERR(root));
 		close_ctree(root);
 		return NULL;
 	}
+out:
+	if (list_roots) {
+		int ret = do_list_roots(root);
+		if (ret) {
+			root = NULL;
+			close_ctree(root);
+		}
+	}
 
 	return root->fs_info->fs_root;
 }
@@ -917,8 +988,9 @@ int main(int argc, char **argv)
 	int match_cflags = REG_EXTENDED | REG_NOSUB | REG_NEWLINE;
 	regex_t match_reg, *mreg = NULL;
 	char reg_err[256];
+	int list_roots = 0;
 
-	while ((opt = getopt(argc, argv, "sviot:u:df:r:cm:")) != -1) {
+	while ((opt = getopt(argc, argv, "sviot:u:df:r:cm:l")) != -1) {
 		switch (opt) {
 			case 's':
 				get_snaps = 1;
@@ -975,13 +1047,19 @@ int main(int argc, char **argv)
 			case 'm':
 				match_regstr = optarg;
 				break;
+			case 'l':
+				list_roots = 1;
+				break;
 			default:
 				usage();
 				exit(1);
 		}
 	}
 
-	if (optind + 1 >= argc) {
+	if (!list_roots && optind + 1 >= argc) {
+		usage();
+		exit(1);
+	} else if (list_roots && optind >= argc) {
 		usage();
 		exit(1);
 	}
@@ -995,10 +1073,13 @@ int main(int argc, char **argv)
 		return -EBUSY;
 	}
 
-	root = open_fs(argv[optind], tree_location, super_mirror);
+	root = open_fs(argv[optind], tree_location, super_mirror, list_roots);
 	if (root == NULL)
 		return 1;
 
+	if (list_roots)
+		goto out;
+
 	if (fs_location != 0) {
 		free_extent_buffer(root->node);
 		root->node = read_tree_block(root, fs_location, 4096, 0);
-- 
1.7.6.233.gd79bc