kernel - Fix excessive mbuf use in nfs_realign()
[dragonfly.git] / sys / vfs / hammer / hammer_cursor.h
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1/*
2 * Copyright (c) 2007 The DragonFly Project. All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
5c8d05e2 34 * $DragonFly: src/sys/vfs/hammer/hammer_cursor.h,v 1.26 2008/08/06 15:38:58 dillon Exp $
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35 */
36
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37struct hammer_cmirror;
38
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39/*
40 * The hammer_cursor structure is the primary in-memory management structure
41 * for B-Tree operations.
42 *
43 * The most important issue to make note of is that a hammer_cursor is a
44 * tracking structure. Any active hammer_cursor structure will be linked into
45 * hammer_node based lists and B-Tree operations executed by unrelated
46 * treads MAY MODIFY YOUR CURSOR when you are not holding an exclusive
47 * lock on the cursor's nodes.
48 *
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49 * The cursor module maintains a shared lock on cursor->node and
50 * cursor->parent.
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51 */
52struct hammer_cursor {
53 /*
54 * Parent B-Tree node, current B-Tree node, and related element
55 * indices.
56 */
36f82b23 57 hammer_transaction_t trans;
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58 hammer_node_t parent;
59 int parent_index;
6a37e7e4 60
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61 hammer_node_t node;
62 int index;
8cd0a023 63
6a37e7e4 64 /*
4e17f465 65 * Set if a deadlock occurs. hammer_done_cursor() will block on
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66 * this after releasing parent and node, before returning. See
67 * also hammer_recover_cursor().
6a37e7e4 68 */
b3bad96f 69 TAILQ_ENTRY(hammer_cursor) deadlk_entry;
6a37e7e4 70 hammer_node_t deadlk_node;
b84de5af 71 hammer_record_t deadlk_rec;
6a37e7e4 72
b33e2cc0 73 /*
9582c7da 74 * Set along with HAMMER_CURSOR_CREATE_CHECK when doing an as-of
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75 * search. If ENOENT is returned and the flag is set, the caller
76 * must iterate with a new delete_tid.
77 */
9582c7da 78 hammer_tid_t create_check;
b33e2cc0 79
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80 /*
81 * Pointer to the current node's bounds. Typically points to the
82 * appropriate boundary elements in the parent or points to bounds
83 * stored in the cluster. The right-boundary is range-exclusive.
84 */
85 hammer_base_elm_t left_bound;
86 hammer_base_elm_t right_bound;
87
88 /*
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89 * Key or key range governing search. The cursor code may adjust
90 * key_beg/key_end if asof is non-zero.
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91 */
92 struct hammer_base_elm key_beg;
93 struct hammer_base_elm key_end;
d5530d22 94 hammer_tid_t asof;
4c038e17 95 struct hammer_cmirror *cmirror;
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96
97 /*
98 * Related data and record references. Note that the related buffers
99 * can be NULL when data and/or record is not, typically indicating
100 * information referenced via an in-memory record.
101 */
47197d71 102 struct hammer_buffer *data_buffer; /* extended data */
11ad5ade 103 struct hammer_btree_leaf_elm *leaf;
40043e7f 104 union hammer_data_ondisk *data;
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105
106 /*
107 * Iteration and extraction control variables
108 */
109 int flags;
3214ade6 110 int rec_generation;
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111
112 /*
113 * Merged in-memory/on-disk iterations also use these fields.
114 */
115 struct hammer_inode *ip;
116 struct hammer_record *iprec;
117};
118
119typedef struct hammer_cursor *hammer_cursor_t;
120
11ad5ade 121#define HAMMER_CURSOR_GET_LEAF 0x0001
a89aec1b 122#define HAMMER_CURSOR_GET_DATA 0x0002
b84de5af 123#define HAMMER_CURSOR_BACKEND 0x0004 /* cursor run by backend */
a89aec1b 124#define HAMMER_CURSOR_INSERT 0x0008 /* adjust for insert */
b84de5af 125#define HAMMER_CURSOR_DELETE_VISIBILITY 0x0010 /* special del-on-disk recs */
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126#define HAMMER_CURSOR_END_INCLUSIVE 0x0020 /* key_end is inclusive */
127#define HAMMER_CURSOR_END_EXCLUSIVE 0x0040 /* key_end is exclusive (def) */
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128
129#define HAMMER_CURSOR_ATEDISK 0x0100
130#define HAMMER_CURSOR_ATEMEM 0x0200
131#define HAMMER_CURSOR_DISKEOF 0x0400
132#define HAMMER_CURSOR_MEMEOF 0x0800
5c8d05e2 133#define HAMMER_CURSOR_RETEST 0x1000 /* retest current element */
c82af904 134#define HAMMER_CURSOR_MIRROR_FILTERED 0x2000 /* mirror_tid filter */
d5530d22 135#define HAMMER_CURSOR_ASOF 0x4000 /* as-of lookup */
9582c7da 136#define HAMMER_CURSOR_CREATE_CHECK 0x8000 /* as-of lookup */
8cd0a023 137
11ad5ade 138#define HAMMER_CURSOR_PRUNING 0x00010000
2f85fa4d 139#define HAMMER_CURSOR_REBLOCKING 0x00020000
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140#define HAMMER_CURSOR_TRACKED 0x00040000
141#define HAMMER_CURSOR_TRACKED_RIPOUT 0x00080000
3214ade6 142#define HAMMER_CURSOR_LASTWASMEM 0x00100000 /* hammer_ip_next logic */
6dc17446 143#define HAMMER_CURSOR_ITERATE_CHECK 0x00200000
11ad5ade 144
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145/*
146 * Flags we can clear when reusing a cursor (we can clear all of them)
147 */
148#define HAMMER_CURSOR_INITMASK (~0)
149
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150/*
151 * Mirror scan extension structure. Caller sets mirror_tid to restrict
152 * the scan. If the iteration is able to skip one or more internal nodes
153 * it returns an internal node with skip_beg/end set to the skipped range.
154 *
155 * If the first element of an internal node is skipped skip_beg will use
156 * the left_bound inherited from the parent, and the same for the last
157 * element. This is because gaps can develop in the bounds.
158 */
159struct hammer_cmirror {
160 hammer_tid_t mirror_tid;
161 struct hammer_base_elm skip_beg;
162 struct hammer_base_elm skip_end;
163};
164
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165/*
166 * NOTE: iprec can be NULL, but the address-of does not indirect through
167 * it so we are ok.
168 */
169#define hammer_cursor_inmem(cursor) \
170 ((cursor)->leaf == &(cursor)->iprec->leaf)
171#define hammer_cursor_ondisk(cursor) \
172 ((cursor)->leaf != &(cursor)->iprec->leaf)
173