btrfs-list.c

/*
 * Copyright (C) 2010 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.
 */

#define _GNU_SOURCE
#ifndef __CHECKER__
#include <sys/ioctl.h>
#include <sys/mount.h>
#include "ioctl.h"
#endif
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#include <libgen.h>
#include "kerncompat.h"
#include "ctree.h"
#include "transaction.h"
#include "utils.h"

/* we store all the roots we find in an rbtree so that we can
 * search for them later.
 */
struct root_lookup {
	struct rb_root root;
};

/*
 * one of these for each root we find.
 */
struct root_info {
	struct rb_node rb_node;

	/* this root's id */
	u64 root_id;

	/* the id of the root that references this one */
	u64 ref_tree;

	/* the dir id we're in from ref_tree */
	u64 dir_id;

	/* path from the subvol we live in to this root, including the
	 * root's name.  This is null until we do the extra lookup ioctl.
	 */
	char *path;

	/* the name of this root in the directory it lives in */
	char name[];
};

static void root_lookup_init(struct root_lookup *tree)
{
	tree->root.rb_node = NULL;
}

static int comp_entry(struct root_info *entry, u64 root_id, u64 ref_tree)
{
	if (entry->root_id > root_id)
		return 1;
	if (entry->root_id < root_id)
		return -1;
	if (entry->ref_tree > ref_tree)
		return 1;
	if (entry->ref_tree < ref_tree)
		return -1;
	return 0;
}

/*
 * insert a new root into the tree.  returns the existing root entry
 * if one is already there.  Both root_id and ref_tree are used
 * as the key
 */
static struct rb_node *tree_insert(struct rb_root *root, u64 root_id,
				   u64 ref_tree, struct rb_node *node)
{
	struct rb_node ** p = &root->rb_node;
	struct rb_node * parent = NULL;
	struct root_info *entry;
	int comp;

	while(*p) {
		parent = *p;
		entry = rb_entry(parent, struct root_info, rb_node);

		comp = comp_entry(entry, root_id, ref_tree);

		if (comp < 0)
			p = &(*p)->rb_left;
		else if (comp > 0)
			p = &(*p)->rb_right;
		else
			return parent;
	}

	entry = rb_entry(parent, struct root_info, rb_node);
	rb_link_node(node, parent, p);
	rb_insert_color(node, root);
	return NULL;
}

/*
 * find a given root id in the tree.  We return the smallest one,
 * rb_next can be used to move forward looking for more if required
 */
static struct root_info *tree_search(struct rb_root *root, u64 root_id)
{
	struct rb_node * n = root->rb_node;
	struct root_info *entry;

	while(n) {
		entry = rb_entry(n, struct root_info, rb_node);

		if (entry->root_id < root_id)
			n = n->rb_left;
		else if (entry->root_id > root_id)
			n = n->rb_right;
		else {
			struct root_info *prev;
			struct rb_node *prev_n;
			while (1) {
				prev_n = rb_prev(n);
				if (!prev_n)
					break;
				prev = rb_entry(prev_n, struct root_info,
						      rb_node);
				if (prev->root_id != root_id)
					break;
				entry = prev;
				n = prev_n;
			}
			return entry;
		}
	}
	return NULL;
}

/*
 * this allocates a new root in the lookup tree.
 *
 * root_id should be the object id of the root
 *
 * ref_tree is the objectid of the referring root.
 *
 * dir_id is the directory in ref_tree where this root_id can be found.
 *
 * name is the name of root_id in that directory
 *
 * name_len is the length of name
 */
static int add_root(struct root_lookup *root_lookup,
		    u64 root_id, u64 ref_tree, u64 dir_id, char *name,
		    int name_len)
{
	struct root_info *ri;
	struct rb_node *ret;
	ri = malloc(sizeof(*ri) + name_len + 1);
	if (!ri) {
		printf("memory allocation failed\n");
		exit(1);
	}
	memset(ri, 0, sizeof(*ri) + name_len + 1);
	ri->path = NULL;
	ri->dir_id = dir_id;
	ri->root_id = root_id;
	ri->ref_tree = ref_tree;
	strncpy(ri->name, name, name_len);

	ret = tree_insert(&root_lookup->root, root_id, ref_tree, &ri->rb_node);
	if (ret) {
		printf("failed to insert tree %llu\n", (unsigned long long)root_id);
		exit(1);
	}
	return 0;
}

/*
 * for a given root_info, search through the root_lookup tree to construct
 * the full path name to it.
 *
 * This can't be called until all the root_info->path fields are filled
 * in by lookup_ino_path
 */
static int resolve_root(struct root_lookup *rl, struct root_info *ri, int print_parent)
{
	u64 top_id;
	u64 parent_id = 0;
	char *full_path = NULL;
	int len = 0;
	struct root_info *found;

	/*
	 * we go backwards from the root_info object and add pathnames
	 * from parent directories as we go.
	 */
	found = ri;
	while (1) {
		char *tmp;
		u64 next;
		int add_len = strlen(found->path);

		/* room for / and for null */
		tmp = malloc(add_len + 2 + len);
		if (full_path) {
			memcpy(tmp + add_len + 1, full_path, len);
			tmp[add_len] = '/';
			memcpy(tmp, found->path, add_len);
			tmp [add_len + len + 1] = '\0';
			free(full_path);
			full_path = tmp;
			len += add_len + 1;
		} else {
			full_path = strdup(found->path);
			len = add_len;
		}

		next = found->ref_tree;
		/* record the first parent */
		if ( parent_id == 0 ) {
			parent_id = next;
		}

		/* if the ref_tree refers to ourselves, we're at the top */
		if (next == found->root_id) {
			top_id = next;
			break;
		}

		/*
		 * if the ref_tree wasn't in our tree of roots, we're
		 * at the top
		 */
		found = tree_search(&rl->root, next);
		if (!found) {
			top_id = next;
			break;
		}
	}
	if (print_parent) {
		printf("ID %llu parent %llu top level %llu path %s\n",
		       (unsigned long long)ri->root_id, (unsigned long long)parent_id, (unsigned long long)top_id,
			full_path);
	} else {
		printf("ID %llu top level %llu path %s\n",
		       (unsigned long long)ri->root_id, (unsigned long long)top_id,
			full_path);
	}
	free(full_path);
	return 0;
}

/*
 * for a single root_info, ask the kernel to give us a path name
 * inside it's ref_root for the dir_id where it lives.
 *
 * This fills in root_info->path with the path to the directory and and
 * appends this root's name.
 */
static int lookup_ino_path(int fd, struct root_info *ri)
{
	struct btrfs_ioctl_ino_lookup_args args;
	int ret, e;

	if (ri->path)
		return 0;

	memset(&args, 0, sizeof(args));
	args.treeid = ri->ref_tree;
	args.objectid = ri->dir_id;

	ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
	e = errno;
	if (ret) {
		fprintf(stderr, "ERROR: Failed to lookup path for root %llu - %s\n",
			(unsigned long long)ri->ref_tree,
			strerror(e));
		return ret;
	}

	if (args.name[0]) {
		/*
		 * we're in a subdirectory of ref_tree, the kernel ioctl
		 * puts a / in there for us
		 */
		ri->path = malloc(strlen(ri->name) + strlen(args.name) + 1);
		if (!ri->path) {
			perror("malloc failed");
			exit(1);
		}
		strcpy(ri->path, args.name);
		strcat(ri->path, ri->name);
	} else {
		/* we're at the root of ref_tree */
		ri->path = strdup(ri->name);
		if (!ri->path) {
			perror("strdup failed");
			exit(1);
		}
	}
	return 0;
}

/* finding the generation for a given path is a two step process.
 * First we use the inode loookup routine to find out the root id
 *
 * Then we use the tree search ioctl to scan all the root items for a
 * given root id and spit out the latest generation we can find
 */
static u64 find_root_gen(int fd)
{
	struct btrfs_ioctl_ino_lookup_args ino_args;
	int ret;
	struct btrfs_ioctl_search_args args;
	struct btrfs_ioctl_search_key *sk = &args.key;
	struct btrfs_ioctl_search_header *sh;
	unsigned long off = 0;
	u64 max_found = 0;
	int i;
	int e;

	memset(&ino_args, 0, sizeof(ino_args));
	ino_args.objectid = BTRFS_FIRST_FREE_OBJECTID;

	/* this ioctl fills in ino_args->treeid */
	ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_args);
	e = errno;
	if (ret) {
		fprintf(stderr, "ERROR: Failed to lookup path for dirid %llu - %s\n",
			(unsigned long long)BTRFS_FIRST_FREE_OBJECTID,
			strerror(e));
		return 0;
	}

	memset(&args, 0, sizeof(args));

	sk->tree_id = 1;

	/*
	 * there may be more than one ROOT_ITEM key if there are
	 * snapshots pending deletion, we have to loop through
	 * them.
	 */
	sk->min_objectid = ino_args.treeid;
	sk->max_objectid = ino_args.treeid;
	sk->max_type = BTRFS_ROOT_ITEM_KEY;
	sk->min_type = BTRFS_ROOT_ITEM_KEY;
	sk->max_offset = (u64)-1;
	sk->max_transid = (u64)-1;
	sk->nr_items = 4096;

	while (1) {
		ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
		e = errno;
		if (ret < 0) {
			fprintf(stderr, "ERROR: can't perform the search - %s\n",
				strerror(e));
			return 0;
		}
		/* the ioctl returns the number of item it found in nr_items */
		if (sk->nr_items == 0)
			break;

		off = 0;
		for (i = 0; i < sk->nr_items; i++) {
			struct btrfs_root_item *item;
			sh = (struct btrfs_ioctl_search_header *)(args.buf +
								  off);

			off += sizeof(*sh);
			item = (struct btrfs_root_item *)(args.buf + off);
			off += sh->len;

			sk->min_objectid = sh->objectid;
			sk->min_type = sh->type;
			sk->min_offset = sh->offset;

			if (sh->objectid > ino_args.treeid)
				break;

			if (sh->objectid == ino_args.treeid &&
			    sh->type == BTRFS_ROOT_ITEM_KEY) {
				max_found = max(max_found,
						btrfs_root_generation(item));
			}
		}
		if (sk->min_offset < (u64)-1)
			sk->min_offset++;
		else
			break;

		if (sk->min_type != BTRFS_ROOT_ITEM_KEY)
			break;
		if (sk->min_objectid != BTRFS_ROOT_ITEM_KEY)
			break;
	}
	return max_found;
}

/* pass in a directory id and this will return
 * the full path of the parent directory inside its
 * subvolume root.
 *
 * It may return NULL if it is in the root, or an ERR_PTR if things
 * go badly.
 */
static char *__ino_resolve(int fd, u64 dirid)
{
	struct btrfs_ioctl_ino_lookup_args args;
	int ret;
	char *full;
	int e;

	memset(&args, 0, sizeof(args));
	args.objectid = dirid;

	ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args);
	e = errno;
	if (ret) {
		fprintf(stderr, "ERROR: Failed to lookup path for dirid %llu - %s\n",
			(unsigned long long)dirid, strerror(e) );
		return ERR_PTR(ret);
	}

	if (args.name[0]) {
		/*
		 * we're in a subdirectory of ref_tree, the kernel ioctl
		 * puts a / in there for us
		 */
		full = strdup(args.name);
		if (!full) {
			perror("malloc failed");
			return ERR_PTR(-ENOMEM);
		}
	} else {
		/* we're at the root of ref_tree */
		full = NULL;
	}
	return full;
}

/*
 * simple string builder, returning a new string with both
 * dirid and name
 */
char *build_name(char *dirid, char *name)
{
	char *full;
	if (!dirid)
		return strdup(name);

	full = malloc(strlen(dirid) + strlen(name) + 1);
	if (!full)
		return NULL;
	strcpy(full, dirid);
	strcat(full, name);
	return full;
}

/*
 * given an inode number, this returns the full path name inside the subvolume
 * to that file/directory.  cache_dirid and cache_name are used to
 * cache the results so we can avoid tree searches if a later call goes
 * to the same directory or file name
 */
static char *ino_resolve(int fd, u64 ino, u64 *cache_dirid, char **cache_name)

{
	u64 dirid;
	char *dirname;
	char *name;
	char *full;
	int ret;
	struct btrfs_ioctl_search_args args;
	struct btrfs_ioctl_search_key *sk = &args.key;
	struct btrfs_ioctl_search_header *sh;
	unsigned long off = 0;
	int namelen;
	int e;

	memset(&args, 0, sizeof(args));

	sk->tree_id = 0;

	/*
	 * step one, we search for the inode back ref.  We just use the first
	 * one
	 */
	sk->min_objectid = ino;
	sk->max_objectid = ino;
	sk->max_type = BTRFS_INODE_REF_KEY;
	sk->max_offset = (u64)-1;
	sk->min_type = BTRFS_INODE_REF_KEY;
	sk->max_transid = (u64)-1;
	sk->nr_items = 1;

	ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
	e = errno;
	if (ret < 0) {
		fprintf(stderr, "ERROR: can't perform the search - %s\n",
			strerror(e));
		return NULL;
	}
	/* the ioctl returns the number of item it found in nr_items */
	if (sk->nr_items == 0)
		return NULL;

	off = 0;
	sh = (struct btrfs_ioctl_search_header *)(args.buf + off);

	if (sh->type == BTRFS_INODE_REF_KEY) {
		struct btrfs_inode_ref *ref;
		dirid = sh->offset;

		ref = (struct btrfs_inode_ref *)(sh + 1);
		namelen = btrfs_stack_inode_ref_name_len(ref);

		name = (char *)(ref + 1);
		name = strndup(name, namelen);

		/* use our cached value */
		if (dirid == *cache_dirid && *cache_name) {
			dirname = *cache_name;
			goto build;
		}
	} else {
		return NULL;
	}
	/*
	 * the inode backref gives us the file name and the parent directory id.
	 * From here we use __ino_resolve to get the path to the parent
	 */
	dirname = __ino_resolve(fd, dirid);
build:
	full = build_name(dirname, name);
	if (*cache_name && dirname != *cache_name)
		free(*cache_name);

	*cache_name = dirname;
	*cache_dirid = dirid;
	free(name);

	return full;
}

int list_subvols(int fd, int print_parent, int get_default)
{
	struct root_lookup root_lookup;
	struct rb_node *n;
	int ret;
	struct btrfs_ioctl_search_args args;
	struct btrfs_ioctl_search_key *sk = &args.key;
	struct btrfs_ioctl_search_header *sh;
	struct btrfs_root_ref *ref;
	struct btrfs_dir_item *di;
	unsigned long off = 0;
	int name_len;
	char *name;
	u64 dir_id;
	u64 subvol_id = 0;
	int i;
	int e;

	root_lookup_init(&root_lookup);

	memset(&args, 0, sizeof(args));

	/* search in the tree of tree roots */
	sk->tree_id = 1;

	/*
	 * set the min and max to backref keys.  The search will
	 * only send back this type of key now.
	 */
	sk->max_type = BTRFS_ROOT_BACKREF_KEY;
	sk->min_type = BTRFS_ROOT_BACKREF_KEY;

	/*
	 * set all the other params to the max, we'll take any objectid
	 * and any trans
	 */
	sk->max_objectid = (u64)-1;
	sk->max_offset = (u64)-1;
	sk->max_transid = (u64)-1;

	/* just a big number, doesn't matter much */
	sk->nr_items = 4096;

	while(1) {
		ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
		e = errno;
		if (ret < 0) {
			fprintf(stderr, "ERROR: can't perform the search - %s\n",
				strerror(e));
			return ret;
		}
		/* the ioctl returns the number of item it found in nr_items */
		if (sk->nr_items == 0)
			break;

		off = 0;

		/*
		 * for each item, pull the key out of the header and then
		 * read the root_ref item it contains
		 */
		for (i = 0; i < sk->nr_items; i++) {
			sh = (struct btrfs_ioctl_search_header *)(args.buf +
								  off);
			off += sizeof(*sh);
			if (sh->type == BTRFS_ROOT_BACKREF_KEY) {
				ref = (struct btrfs_root_ref *)(args.buf + off);
				name_len = btrfs_stack_root_ref_name_len(ref);
				name = (char *)(ref + 1);
				dir_id = btrfs_stack_root_ref_dirid(ref);

				add_root(&root_lookup, sh->objectid, sh->offset,
					 dir_id, name, name_len);
			}

			off += sh->len;

			/*
			 * record the mins in sk so we can make sure the
			 * next search doesn't repeat this root
			 */
			sk->min_objectid = sh->objectid;
			sk->min_type = sh->type;
			sk->min_offset = sh->offset;
		}
		sk->nr_items = 4096;
		/* this iteration is done, step forward one root for the next
		 * ioctl
		 */
		if (sk->min_objectid < (u64)-1) {
			sk->min_objectid++;
			sk->min_type = BTRFS_ROOT_BACKREF_KEY;
			sk->min_offset = 0;
		} else
			break;
	}
	/*
	 * now we have an rbtree full of root_info objects, but we need to fill
	 * in their path names within the subvol that is referencing each one.
	 */
	n = rb_first(&root_lookup.root);
	while (n) {
		struct root_info *entry;
		int ret;
		entry = rb_entry(n, struct root_info, rb_node);
		ret = lookup_ino_path(fd, entry);
		if(ret < 0)
			return ret;
		n = rb_next(n);
	}

	memset(&args, 0, sizeof(args));

	/* search in the tree of tree roots */
	sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;

	/* search dir item */
	sk->max_type = BTRFS_DIR_ITEM_KEY;
	sk->min_type = BTRFS_DIR_ITEM_KEY;

	sk->max_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;
	sk->min_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;
	sk->max_offset = (u64)-1;
	sk->max_transid = (u64)-1;

	/* just a big number, doesn't matter much */
	sk->nr_items = 4096;

	/* try to get the objectid of default subvolume */
	if (get_default) {
		ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
		if (ret < 0) {
			fprintf(stderr, "ERROR: can't perform the search\n");
			return ret;
		}

		off = 0;
		/* go through each item to find dir item named "default" */
		for (i = 0; i < sk->nr_items; i++) {
			sh = (struct btrfs_ioctl_search_header *)(args.buf +
								  off);
			off += sizeof(*sh);
			if (sh->type == BTRFS_DIR_ITEM_KEY) {
				di = (struct btrfs_dir_item *)(args.buf + off);
				name_len = le16_to_cpu(di->name_len);
				name = (char *)di + sizeof(struct btrfs_dir_item);
				if (!strncmp("default", name, name_len)) {
					subvol_id = btrfs_disk_key_objectid(
						&di->location);
					break;
				}
			}

			off += sh->len;
		}
	}

	/* now that we have all the subvol-relative paths filled in,
	 * we have to string the subvols together so that we can get
	 * a path all the way back to the FS root
	 */
	n = rb_last(&root_lookup.root);
	while (n) {
		struct root_info *entry;
		entry = rb_entry(n, struct root_info, rb_node);
		if (!get_default)
			resolve_root(&root_lookup, entry, print_parent);
		/* we only want the default subvolume */
		else if (subvol_id == entry->root_id)
			resolve_root(&root_lookup, entry, print_parent);
		else if (subvol_id == 0)
			break;
		n = rb_prev(n);
	}

	return ret;
}

static int print_one_extent(int fd, struct btrfs_ioctl_search_header *sh,
			    struct btrfs_file_extent_item *item,
			    u64 found_gen, u64 *cache_dirid,
			    char **cache_dir_name, u64 *cache_ino,
			    char **cache_full_name)
{
	u64 len = 0;
	u64 disk_start = 0;
	u64 disk_offset = 0;
	u8 type;
	int compressed = 0;
	int flags = 0;
	char *name = NULL;

	if (sh->objectid == *cache_ino) {
		name = *cache_full_name;
	} else if (*cache_full_name) {
		free(*cache_full_name);
		*cache_full_name = NULL;
	}
	if (!name) {
		name = ino_resolve(fd, sh->objectid, cache_dirid,
				   cache_dir_name);
		*cache_full_name = name;
		*cache_ino = sh->objectid;
	}
	if (!name)
		return -EIO;

	type = btrfs_stack_file_extent_type(item);
	compressed = btrfs_stack_file_extent_compression(item);

	if (type == BTRFS_FILE_EXTENT_REG ||
	    type == BTRFS_FILE_EXTENT_PREALLOC) {
		disk_start = btrfs_stack_file_extent_disk_bytenr(item);
		disk_offset = btrfs_stack_file_extent_offset(item);
		len = btrfs_stack_file_extent_num_bytes(item);
	} else if (type == BTRFS_FILE_EXTENT_INLINE) {
		disk_start = 0;
		disk_offset = 0;
		len = btrfs_stack_file_extent_ram_bytes(item);
	} else {
		printf("unhandled extent type %d for inode %llu "
		       "file offset %llu gen %llu\n",
			type,
			(unsigned long long)sh->objectid,
			(unsigned long long)sh->offset,
			(unsigned long long)found_gen);

		return -EIO;
	}
	printf("inode %llu file offset %llu len %llu disk start %llu "
	       "offset %llu gen %llu flags ",
	       (unsigned long long)sh->objectid,
	       (unsigned long long)sh->offset,
	       (unsigned long long)len,
	       (unsigned long long)disk_start,
	       (unsigned long long)disk_offset,
	       (unsigned long long)found_gen);

	if (compressed) {
		printf("COMPRESS");
		flags++;
	}
	if (type == BTRFS_FILE_EXTENT_PREALLOC) {
		printf("%sPREALLOC", flags ? "|" : "");
		flags++;
	}
	if (type == BTRFS_FILE_EXTENT_INLINE) {
		printf("%sINLINE", flags ? "|" : "");
		flags++;
	}
	if (!flags)
		printf("NONE");

	printf(" %s\n", name);
	return 0;
}

int find_updated_files(int fd, u64 root_id, u64 oldest_gen)
{
	int ret;
	struct btrfs_ioctl_search_args args;
	struct btrfs_ioctl_search_key *sk = &args.key;
	struct btrfs_ioctl_search_header *sh;
	struct btrfs_file_extent_item *item;
	unsigned long off = 0;
	u64 found_gen;
	u64 max_found = 0;
	int i;
	int e;
	u64 cache_dirid = 0;
	u64 cache_ino = 0;
	char *cache_dir_name = NULL;
	char *cache_full_name = NULL;
	struct btrfs_file_extent_item backup;

	memset(&backup, 0, sizeof(backup));
	memset(&args, 0, sizeof(args));

	sk->tree_id = root_id;

	/*
	 * set all the other params to the max, we'll take any objectid
	 * and any trans
	 */
	sk->max_objectid = (u64)-1;
	sk->max_offset = (u64)-1;
	sk->max_transid = (u64)-1;
	sk->max_type = BTRFS_EXTENT_DATA_KEY;
	sk->min_transid = oldest_gen;
	/* just a big number, doesn't matter much */
	sk->nr_items = 4096;

	max_found = find_root_gen(fd);
	while(1) {
		ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
		e = errno;
		if (ret < 0) {
			fprintf(stderr, "ERROR: can't perform the search- %s\n",
				strerror(e));
			return ret;
		}
		/* the ioctl returns the number of item it found in nr_items */
		if (sk->nr_items == 0)
			break;

		off = 0;

		/*
		 * for each item, pull the key out of the header and then
		 * read the root_ref item it contains
		 */
		for (i = 0; i < sk->nr_items; i++) {
			sh = (struct btrfs_ioctl_search_header *)(args.buf +
								  off);
			off += sizeof(*sh);

			/*
			 * just in case the item was too big, pass something other
			 * than garbage
			 */
			if (sh->len == 0)
				item = &backup;
			else
				item = (struct btrfs_file_extent_item *)(args.buf +
								 off);
			found_gen = btrfs_stack_file_extent_generation(item);
			if (sh->type == BTRFS_EXTENT_DATA_KEY &&
			    found_gen >= oldest_gen) {
				print_one_extent(fd, sh, item, found_gen,
						 &cache_dirid, &cache_dir_name,
						 &cache_ino, &cache_full_name);
			}
			off += sh->len;

			/*
			 * record the mins in sk so we can make sure the
			 * next search doesn't repeat this root
			 */
			sk->min_objectid = sh->objectid;
			sk->min_offset = sh->offset;
			sk->min_type = sh->type;
		}
		sk->nr_items = 4096;
		if (sk->min_offset < (u64)-1)
			sk->min_offset++;
		else if (sk->min_objectid < (u64)-1) {
			sk->min_objectid++;
			sk->min_offset = 0;
			sk->min_type = 0;
		} else
			break;
	}
	free(cache_dir_name);
	free(cache_full_name);
	printf("transid marker was %llu\n", (unsigned long long)max_found);
	return ret;
}