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c995ab3cda
The LOGICAL_INO ioctl provides a backward mapping from extent bytenr and offset (encoded as a single logical address) to a list of extent refs. LOGICAL_INO complements TREE_SEARCH, which provides the forward mapping (extent ref -> extent bytenr and offset, or logical address). These are useful capabilities for programs that manipulate extents and extent references from userspace (e.g. dedup and defrag utilities). When the extents are uncompressed (and not encrypted and not other), check_extent_in_eb performs filtering of the extent refs to remove any extent refs which do not contain the same extent offset as the 'logical' parameter's extent offset. This prevents LOGICAL_INO from returning references to more than a single block. To find the set of extent references to an uncompressed extent from [a, b), userspace has to run a loop like this pseudocode: for (i = a; i < b; ++i) extent_ref_set += LOGICAL_INO(i); At each iteration of the loop (up to 32768 iterations for a 128M extent), data we are interested in is collected in the kernel, then deleted by the filter in check_extent_in_eb. When the extents are compressed (or encrypted or other), the 'logical' parameter must be an extent bytenr (the 'a' parameter in the loop). No filtering by extent offset is done (or possible?) so the result is the complete set of extent refs for the entire extent. This removes the need for the loop, since we get all the extent refs in one call. Add an 'ignore_offset' argument to iterate_inodes_from_logical, [...several levels of function call graph...], and check_extent_in_eb, so that we can disable the extent offset filtering for uncompressed extents. This flag can be set by an improved version of the LOGICAL_INO ioctl to get either behavior as desired. There is no functional change in this patch. The new flag is always false. Signed-off-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org> Reviewed-by: David Sterba <dsterba@suse.com> [ minor coding style fixes ] Signed-off-by: David Sterba <dsterba@suse.com>
90 lines
2.9 KiB
C
90 lines
2.9 KiB
C
/*
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* Copyright (C) 2011 STRATO. 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 __BTRFS_BACKREF__
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#define __BTRFS_BACKREF__
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#include <linux/btrfs.h>
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#include "ulist.h"
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#include "extent_io.h"
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struct inode_fs_paths {
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struct btrfs_path *btrfs_path;
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struct btrfs_root *fs_root;
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struct btrfs_data_container *fspath;
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};
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typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 root,
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void *ctx);
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int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
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struct btrfs_path *path, struct btrfs_key *found_key,
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u64 *flags);
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int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
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struct btrfs_key *key, struct btrfs_extent_item *ei,
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u32 item_size, u64 *out_root, u8 *out_level);
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int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
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u64 extent_item_objectid,
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u64 extent_offset, int search_commit_root,
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iterate_extent_inodes_t *iterate, void *ctx,
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bool ignore_offset);
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int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
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struct btrfs_path *path,
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iterate_extent_inodes_t *iterate, void *ctx,
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bool ignore_offset);
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int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);
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int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info, u64 bytenr,
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u64 time_seq, struct ulist **roots, bool ignore_offset);
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char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
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u32 name_len, unsigned long name_off,
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struct extent_buffer *eb_in, u64 parent,
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char *dest, u32 size);
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struct btrfs_data_container *init_data_container(u32 total_bytes);
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struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
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struct btrfs_path *path);
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void free_ipath(struct inode_fs_paths *ipath);
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int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
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u64 start_off, struct btrfs_path *path,
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struct btrfs_inode_extref **ret_extref,
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u64 *found_off);
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int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr);
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int __init btrfs_prelim_ref_init(void);
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void btrfs_prelim_ref_exit(void);
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struct prelim_ref {
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struct rb_node rbnode;
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u64 root_id;
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struct btrfs_key key_for_search;
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int level;
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int count;
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struct extent_inode_elem *inode_list;
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u64 parent;
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u64 wanted_disk_byte;
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};
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#endif
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