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a37f232b7b
Due to the complex nature of btrfs extent tree, when we want to iterate
all backrefs of one extent, this involves quite a lot of work, like
searching the EXTENT_ITEM/METADATA_ITEM, iteration through inline and keyed
backrefs.
Normally this would result in a complex code, something like:
btrfs_search_slot()
/* Ensure we are at EXTENT_ITEM/METADATA_ITEM */
while (1) { /* Loop for extent tree items */
while (ptr < end) { /* Loop for inlined items */
/* Real work here */
}
next:
ret = btrfs_next_item()
/* Ensure we're still at keyed item for specified bytenr */
}
The idea of btrfs_backref_iter is to avoid such complex and hard to
read code structure, but something like the following:
iter = btrfs_backref_iter_alloc();
ret = btrfs_backref_iter_start(iter, bytenr);
if (ret < 0)
goto out;
for (; ; ret = btrfs_backref_iter_next(iter)) {
/* Real work here */
}
out:
btrfs_backref_iter_free(iter);
This patch is just the skeleton + btrfs_backref_iter_start() code.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
120 lines
3.4 KiB
C
120 lines
3.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2011 STRATO. All rights reserved.
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*/
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#ifndef BTRFS_BACKREF_H
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#define BTRFS_BACKREF_H
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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_leafs(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 **leafs,
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const u64 *extent_item_pos, bool ignore_offset);
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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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struct ulist *roots, struct ulist *tmp_ulist);
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int __init btrfs_prelim_ref_init(void);
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void __cold 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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/*
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* Iterate backrefs of one extent.
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*
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* Now it only supports iteration of tree block in commit root.
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*/
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struct btrfs_backref_iter {
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u64 bytenr;
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struct btrfs_path *path;
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struct btrfs_fs_info *fs_info;
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struct btrfs_key cur_key;
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u32 item_ptr;
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u32 cur_ptr;
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u32 end_ptr;
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};
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struct btrfs_backref_iter *btrfs_backref_iter_alloc(
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struct btrfs_fs_info *fs_info, gfp_t gfp_flag);
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static inline void btrfs_backref_iter_free(struct btrfs_backref_iter *iter)
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{
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if (!iter)
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return;
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btrfs_free_path(iter->path);
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kfree(iter);
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}
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int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr);
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static inline void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
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{
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iter->bytenr = 0;
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iter->item_ptr = 0;
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iter->cur_ptr = 0;
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iter->end_ptr = 0;
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btrfs_release_path(iter->path);
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memset(&iter->cur_key, 0, sizeof(iter->cur_key));
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}
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#endif
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