2 * Copyright (c) 2008 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
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8 * modification, are permitted provided that the following conditions
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13 * 2. Redistributions in binary form must reproduce the above copyright
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19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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34 * $DragonFly: src/sys/vfs/hammer/hammer_undo.c,v 1.4 2008/04/22 19:00:15 dillon Exp $
38 * HAMMER undo - undo buffer/FIFO management.
44 * Convert a zone-3 undo offset into a zone-2 buffer offset.
47 hammer_undo_lookup(hammer_mount_t hmp, hammer_off_t zone3_off, int *errorp)
49 hammer_volume_t root_volume;
50 hammer_blockmap_t undomap;
51 struct hammer_blockmap_layer2 *layer2;
52 hammer_off_t result_offset;
55 KKASSERT((zone3_off & HAMMER_OFF_ZONE_MASK) == HAMMER_ZONE_UNDO);
56 root_volume = hammer_get_root_volume(hmp, errorp);
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);
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);
68 hammer_rel_volume(root_volume, 0);
69 return(result_offset);
73 * Generate an UNDO record for the block of data at the specified zone1
77 hammer_generate_undo(hammer_transaction_t trans, hammer_io_t io,
78 hammer_off_t zone1_off, void *base, int len)
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;
93 bytes = ((len + 7) & ~7) + sizeof(struct hammer_fifo_undo) +
94 sizeof(struct hammer_fifo_tail);
96 root_volume = trans->rootvol;
97 ondisk = root_volume->ondisk;
98 undomap = &ondisk->vol0_blockmap[HAMMER_ZONE_UNDO_INDEX];
100 /* no undo recursion */
101 hammer_modify_volume(NULL, root_volume, NULL, 0);
104 * Allocate space in the FIFO
107 next_offset = undomap->next_offset;
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");
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);
123 undo = hammer_bread(trans->hmp, result_offset, &error, &buffer);
126 * We raced another thread, try again.
128 if (undomap->next_offset != next_offset)
131 hammer_modify_buffer(NULL, buffer, NULL, 0);
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.
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;
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;
154 if (hammer_debug_general & 0x0080)
155 kprintf("undo %016llx %d %d\n", result_offset, bytes, len);
158 * We're good, create the entry.
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->head.reserved01 = 0;
164 undo->head.hdr_crc = 0;
165 undo->undo_offset = zone1_off;
166 undo->undo_data_bytes = len;
167 bcopy(base, undo + 1, len);
168 undo->head.hdr_crc = crc32(undo, bytes);
171 * Update the undo offset space in the IO XXX
175 undomap->next_offset += bytes;
178 hammer_rel_buffer(buffer, 0);