sys/vfs/hammer/hammer_undo.c

   1 /*
   2  * Copyright (c) 2008 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_undo.c,v 1.3 2008/03/24 23:50:23 dillon Exp $
  35  */
  36
  37 /*
  38  * HAMMER undo - undo buffer/FIFO management.
  39  */
  40
  41 #include "hammer.h"
  42
  43 /*
  44  * Convert a zone-3 undo offset into a zone-2 buffer offset.
  45  */
  46 hammer_off_t
  47 hammer_undo_lookup(hammer_mount_t hmp, hammer_off_t zone3_off, int *errorp)
  48 {
  49         hammer_volume_t root_volume;
  50         hammer_blockmap_t undomap;
  51         struct hammer_blockmap_layer2 *layer2;
  52         hammer_off_t result_offset;
  53         int i;
  54
  55         KKASSERT((zone3_off & HAMMER_OFF_ZONE_MASK) == HAMMER_ZONE_UNDO);
  56         root_volume = hammer_get_root_volume(hmp, errorp);
  57         if (*errorp)
  58                 return(0);
  59         undomap = &root_volume->ondisk->vol0_blockmap[HAMMER_ZONE_UNDO_INDEX];
  60         KKASSERT(HAMMER_ZONE_DECODE(undomap->alloc_offset) == HAMMER_ZONE_UNDO_INDEX);
  61         KKASSERT (zone3_off < undomap->alloc_offset);
  62
  63         i = (zone3_off & HAMMER_OFF_SHORT_MASK) / HAMMER_LARGEBLOCK_SIZE;
  64         layer2 = &root_volume->ondisk->vol0_undo_array[i];
  65         result_offset = layer2->u.phys_offset +
  66                         (zone3_off & HAMMER_LARGEBLOCK_MASK64);
  67
  68         hammer_rel_volume(root_volume, 0);
  69         return(result_offset);
  70 }
  71
  72 /*
  73  * Generate an UNDO record for the block of data at the specified zone1
  74  * offset.
  75  */
  76 int
  77 hammer_generate_undo(hammer_transaction_t trans, hammer_off_t zone1_off,
  78                      void *base, int len)
  79 {
  80         hammer_volume_t root_volume;
  81         hammer_volume_ondisk_t ondisk;
  82         hammer_blockmap_t undomap;
  83         hammer_buffer_t buffer = NULL;
  84         struct hammer_blockmap_layer2 *layer2;
  85         hammer_fifo_undo_t undo;
  86         hammer_fifo_tail_t tail;
  87         hammer_off_t next_offset;
  88         hammer_off_t result_offset;
  89         int i;
  90         int error;
  91         int bytes;
  92
  93         bytes = ((len + 7) & ~7) + sizeof(struct hammer_fifo_undo) +
  94                 sizeof(struct hammer_fifo_tail);
  95
  96         root_volume = trans->rootvol;
  97         ondisk = root_volume->ondisk;
  98         undomap = &ondisk->vol0_blockmap[HAMMER_ZONE_UNDO_INDEX];
  99
 100         /* no undo recursion */
 101         hammer_modify_volume(NULL, root_volume, NULL, 0);
 102
 103         /*
 104          * Allocate space in the FIFO
 105          */
 106 again:
 107         next_offset = undomap->next_offset;
 108
 109         /*
 110          * Wrap next_offset
 111          */
 112         if (undomap->next_offset == undomap->alloc_offset) {
 113                 next_offset = HAMMER_ZONE_ENCODE(HAMMER_ZONE_UNDO_INDEX, 0);
 114                 undomap->next_offset = next_offset;
 115                 kprintf("undo zone's next_offset wrapped\n");
 116         }
 117
 118         i = (next_offset & HAMMER_OFF_SHORT_MASK) / HAMMER_LARGEBLOCK_SIZE;
 119         layer2 = &root_volume->ondisk->vol0_undo_array[i];
 120         result_offset = layer2->u.phys_offset +
 121                         (next_offset & HAMMER_LARGEBLOCK_MASK64);
 122
 123         undo = hammer_bread(trans->hmp, result_offset, &error, &buffer);
 124
 125         /*
 126          * We raced another thread, try again.
 127          */
 128         if (undomap->next_offset != next_offset)
 129                 goto again;
 130
 131         hammer_modify_buffer(NULL, buffer, NULL, 0);
 132
 133         /*
 134          * The FIFO entry would cross a buffer boundary, PAD to the end
 135          * of the buffer and try again.  Due to our data alignment, the
 136          * worst case (smallest) PAD record is 8 bytes.  PAD records only
 137          * populate the first 8 bytes of hammer_fifo_head and the tail may
 138          * be at the same offset as the head.
 139          */
 140         if ((result_offset ^ (result_offset + bytes)) & ~HAMMER_BUFMASK64) {
 141                 bytes = HAMMER_BUFSIZE - ((int)next_offset & HAMMER_BUFMASK);
 142                 tail = (void *)((char *)undo + bytes - sizeof(*tail));
 143                 if ((void *)undo != (void *)tail) {
 144                         tail->tail_signature = HAMMER_TAIL_SIGNATURE;
 145                         tail->tail_type = HAMMER_HEAD_TYPE_PAD;
 146                         tail->tail_size = bytes;
 147                 }
 148                 undo->head.hdr_signature = HAMMER_HEAD_SIGNATURE;
 149                 undo->head.hdr_type = HAMMER_HEAD_TYPE_PAD;
 150                 undo->head.hdr_size = bytes;
 151                 undomap->next_offset += bytes;
 152                 goto again;
 153         }
 154         if (hammer_debug_general & 0x0080)
 155                 kprintf("undo %016llx %d %d\n", result_offset, bytes, len);
 156
 157         /*
 158          * We're good, create the entry.
 159          */
 160         undo->head.hdr_signature = HAMMER_HEAD_SIGNATURE;
 161         undo->head.hdr_type = HAMMER_HEAD_TYPE_PAD;
 162         undo->head.hdr_size = bytes;
 163         undo->undo_offset = zone1_off;
 164         undo->undo_data_bytes = len;
 165         bcopy(base, undo + 1, len);
 166         undo->head.hdr_crc = crc32(undo, bytes);
 167
 168         undomap->next_offset += bytes;
 169
 170         if (buffer)
 171                 hammer_rel_buffer(buffer, 0);
 172         return(error);
 173 }
 174