btrfs-progs/send-utils.h

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/*
* Copyright (C) 2012 Alexander Block. 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.
*/
#ifndef __BTRFS_SEND_UTILS_H__
#define __BTRFS_SEND_UTILS_H__
#if BTRFS_FLAT_INCLUDES
#include "kerncompat.h"
#include "ctree.h"
#include "rbtree.h"
#else
#include <btrfs/kerncompat.h>
#include <btrfs/ctree.h>
#include <btrfs/rbtree.h>
#endif /* BTRFS_FLAT_INCLUDES */
#ifdef __cplusplus
extern "C" {
#endif
/*
* Compatibility code for kernels < 3.12; the UUID tree is not available there
* and we have to do the slow search. This should be deprecated someday.
*/
#define BTRFS_COMPAT_SEND_NO_UUID_TREE 1
enum subvol_search_type {
subvol_search_by_root_id,
subvol_search_by_uuid,
subvol_search_by_received_uuid,
subvol_search_by_path,
};
struct subvol_info {
#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
struct rb_node rb_root_id_node;
struct rb_node rb_local_node;
struct rb_node rb_received_node;
struct rb_node rb_path_node;
#endif
u64 root_id;
u8 uuid[BTRFS_UUID_SIZE];
u8 parent_uuid[BTRFS_UUID_SIZE];
u8 received_uuid[BTRFS_UUID_SIZE];
u64 ctransid;
u64 otransid;
u64 stransid;
u64 rtransid;
char *path;
};
struct subvol_uuid_search {
Btrfs-progs: use UUID tree for send/receive This commit changes the btrfs send/receive commands to use the UUID tree to map UUIDs to subvolumes, and to use the root tree to map subvolume IDs to paths. Now these tools start fast and are independent on the number of subvolules/snapshot that exist. Before this commit, mapping UUIDs to subvolume IDs was an operation with a high effort. The algorithm even had quadratic effort (based on the number of existing subvolumes). E.g. with 15,000 subvolumes it took much more than 5 minutes on a state of the art XEON CPU to start btrfs send or receive before these tools were able to send or receive the first byte). Even linear effort instead of the current quadratic effort would be too much since it would be a waste. And these data structures to allow mapping UUIDs to subvolume IDs had been created every time a btrfs send/receive instance was started. It is much more efficient to maintain a searchable persistent data structure in the filesystem, one that is updated whenever a subvolume/snapshot is created and deleted, and when the received subvolume UUID is set by the btrfs-receive tool. Therefore kernel code was added that is able to maintain data structures in the filesystem that allow to quickly search for a given UUID and to retrieve data that is assigned to this UUID, like which subvolume ID is related to this UUID. Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: David Sterba <dsterba@suse.cz> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
2013-06-26 15:17:57 +00:00
int mnt_fd;
#ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
int uuid_tree_existed;
struct rb_root root_id_subvols;
struct rb_root local_subvols;
struct rb_root received_subvols;
struct rb_root path_subvols;
#endif
};
int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s);
void subvol_uuid_search_finit(struct subvol_uuid_search *s);
/*
* Search for a subvolume by given type (received uuid, root id, path), returns
* pointer to newly allocated struct subvol_info or NULL in case it's not found
* or there was another error. This ambiguity of error value is fixed by
* subvol_uuid_search2 that returns a negative errno in case of an error, of a
* valid pointer otherwise.
*
* This function will be deprecated in the future, please consider using v2 in
* new code unless you need to keep backward compatibility with older
* btrfs-progs.
*/
struct subvol_info *subvol_uuid_search(struct subvol_uuid_search *s,
u64 root_id, const u8 *uuid, u64 transid,
const char *path,
enum subvol_search_type type);
struct subvol_info *subvol_uuid_search2(struct subvol_uuid_search *s,
u64 root_id, const u8 *uuid, u64 transid,
const char *path,
enum subvol_search_type type);
void subvol_uuid_search_add(struct subvol_uuid_search *s,
struct subvol_info *si);
int btrfs_subvolid_resolve(int fd, char *path, size_t path_len, u64 subvol_id);
/*
* DEPRECATED: the functions path_cat and path_cat3 are unsafe and should not
* be used, use the _out variants and always check the return code.
*/
__attribute__((deprecated))
char *path_cat(const char *p1, const char *p2);
__attribute__((deprecated))
char *path_cat3(const char *p1, const char *p2, const char *p3);
int path_cat_out(char *out, const char *p1, const char *p2);
int path_cat3_out(char *out, const char *p1, const char *p2, const char *p3);
#ifdef __cplusplus
}
#endif
#endif