mirror of
https://github.com/kdave/btrfs-progs
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5f9c5a23e5
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>
76 lines
2.0 KiB
C
76 lines
2.0 KiB
C
/*
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* Copyright (C) 2012 Alexander Block. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef SEND_UTILS_H_
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#define SEND_UTILS_H_
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#if BTRFS_FLAT_INCLUDES
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#include "ctree.h"
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#include "rbtree.h"
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#else
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#include <btrfs/ctree.h>
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#include <btrfs/rbtree.h>
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#endif /* BTRFS_FLAT_INCLUDES */
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#ifdef __cplusplus
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extern "C" {
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#endif
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enum subvol_search_type {
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subvol_search_by_root_id,
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subvol_search_by_uuid,
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subvol_search_by_received_uuid,
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subvol_search_by_path,
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};
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struct subvol_info {
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u64 root_id;
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u8 uuid[BTRFS_UUID_SIZE];
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u8 parent_uuid[BTRFS_UUID_SIZE];
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u8 received_uuid[BTRFS_UUID_SIZE];
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u64 ctransid;
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u64 otransid;
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u64 stransid;
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u64 rtransid;
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char *path;
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};
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struct subvol_uuid_search {
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int mnt_fd;
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};
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int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s);
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void subvol_uuid_search_finit(struct subvol_uuid_search *s);
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struct subvol_info *subvol_uuid_search(struct subvol_uuid_search *s,
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u64 root_id, const u8 *uuid, u64 transid,
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const char *path,
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enum subvol_search_type type);
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void subvol_uuid_search_add(struct subvol_uuid_search *s,
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struct subvol_info *si);
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int btrfs_subvolid_resolve(int fd, char *path, size_t path_len, u64 subvol_id);
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char *path_cat(const char *p1, const char *p2);
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char *path_cat3(const char *p1, const char *p2, const char *p3);
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#ifdef __cplusplus
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}
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#endif
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#endif /* SEND_UTILS_H_ */
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