sys/vfs/hammer/hammer_cursor.h

   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  *
  34  * $DragonFly: src/sys/vfs/hammer/hammer_cursor.h,v 1.24 2008/07/07 00:24:31 dillon Exp $
  35  */
  36
  37 /*
  38  * The hammer_cursor structure is the primary in-memory management structure
  39  * for B-Tree operations.
  40  *
  41  * The most important issue to make note of is that a hammer_cursor is a
  42  * tracking structure.  Any active hammer_cursor structure will be linked into
  43  * hammer_node based lists and B-Tree operations executed by unrelated
  44  * treads MAY MODIFY YOUR CURSOR when you are not holding an exclusive
  45  * lock on the cursor's nodes.
  46  *
  47  * The cursor module maintains a shared lock on cursor->node and
  48  * cursor->parent.
  49  */
  50 struct hammer_cursor {
  51         /*
  52          * Parent B-Tree node, current B-Tree node, and related element
  53          * indices.
  54          */
  55         hammer_transaction_t trans;
  56         hammer_node_t   parent;
  57         int             parent_index;
  58
  59         hammer_node_t   node;
  60         int             index;
  61
  62         /*
  63          * Set if a deadlock occurs.  hammer_done_cursor() will block on
  64          * this after releasing parent and node, before returning.  See
  65          * also hammer_recover_cursor().
  66          */
  67         TAILQ_ENTRY(hammer_cursor) deadlk_entry;
  68         hammer_node_t deadlk_node;
  69         hammer_record_t deadlk_rec;
  70
  71         /*
  72          * Set along with HAMMER_CURSOR_CREATE_CHECK when doing an as-of
  73          * search.  If ENOENT is returned and the flag is set, the caller
  74          * must iterate with a new delete_tid.
  75          */
  76         hammer_tid_t  create_check;
  77
  78         /*
  79          * Pointer to the current node's bounds.  Typically points to the
  80          * appropriate boundary elements in the parent or points to bounds
  81          * stored in the cluster.  The right-boundary is range-exclusive.
  82          */
  83         hammer_base_elm_t left_bound;
  84         hammer_base_elm_t right_bound;
  85
  86         /*
  87          * Key or key range governing search.  The cursor code may adjust
  88          * key_beg/key_end if asof is non-zero.
  89          */
  90         struct hammer_base_elm key_beg;
  91         struct hammer_base_elm key_end;
  92         hammer_tid_t    asof;
  93         hammer_tid_t    mirror_tid;
  94
  95         /*
  96          * Related data and record references.  Note that the related buffers
  97          * can be NULL when data and/or record is not, typically indicating
  98          * information referenced via an in-memory record.
  99          */
 100         struct hammer_buffer *data_buffer;      /* extended data */
 101         struct hammer_btree_leaf_elm *leaf;
 102         union hammer_data_ondisk *data;
 103
 104         /*
 105          * Iteration and extraction control variables
 106          */
 107         int flags;
 108
 109         /*
 110          * Merged in-memory/on-disk iterations also use these fields.
 111          */
 112         struct hammer_inode *ip;
 113         struct hammer_record *iprec;
 114 };
 115
 116 typedef struct hammer_cursor *hammer_cursor_t;
 117
 118 #define HAMMER_CURSOR_GET_LEAF          0x0001
 119 #define HAMMER_CURSOR_GET_DATA          0x0002
 120 #define HAMMER_CURSOR_BACKEND           0x0004  /* cursor run by backend */
 121 #define HAMMER_CURSOR_INSERT            0x0008  /* adjust for insert */
 122 #define HAMMER_CURSOR_DELETE_VISIBILITY 0x0010  /* special del-on-disk recs */
 123 #define HAMMER_CURSOR_END_INCLUSIVE     0x0020  /* key_end is inclusive */
 124 #define HAMMER_CURSOR_END_EXCLUSIVE     0x0040  /* key_end is exclusive (def) */
 125
 126 #define HAMMER_CURSOR_ATEDISK           0x0100
 127 #define HAMMER_CURSOR_ATEMEM            0x0200
 128 #define HAMMER_CURSOR_DISKEOF           0x0400
 129 #define HAMMER_CURSOR_MEMEOF            0x0800
 130 #define HAMMER_CURSOR_DELBTREE          0x1000  /* ip_delete from b-tree */
 131 #define HAMMER_CURSOR_MIRROR_FILTERED   0x2000  /* mirror_tid filter */
 132 #define HAMMER_CURSOR_ASOF              0x4000  /* as-of lookup */
 133 #define HAMMER_CURSOR_CREATE_CHECK      0x8000  /* as-of lookup */
 134
 135 #define HAMMER_CURSOR_PRUNING           0x00010000
 136 #define HAMMER_CURSOR_REBLOCKING        0x00020000
 137 #define HAMMER_CURSOR_TRACKED           0x00040000
 138 #define HAMMER_CURSOR_TRACKED_RIPOUT    0x00080000
 139
 140 /*
 141  * Flags we can clear when reusing a cursor (we can clear all of them)
 142  */
 143 #define HAMMER_CURSOR_INITMASK          (~0)
 144
 145 /*
 146  * NOTE: iprec can be NULL, but the address-of does not indirect through
 147  * it so we are ok.
 148  */
 149 #define hammer_cursor_inmem(cursor)             \
 150                         ((cursor)->leaf == &(cursor)->iprec->leaf)
 151 #define hammer_cursor_ondisk(cursor)            \
 152                         ((cursor)->leaf != &(cursor)->iprec->leaf)
 153