HAMMER 32/many: Record holes, initial undo API, initial reblocking code
[dragonfly.git] / 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 1.1 2008/03/18 05:19:16 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_mount_t hmp, 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 = hammer_get_root_volume(hmp, &error);
97         if (error)
98                 return(error);
99         ondisk = root_volume->ondisk;
100         undomap = &ondisk->vol0_blockmap[HAMMER_ZONE_UNDO_INDEX];
101         hammer_modify_volume(root_volume, NULL, 0); /* no undo recursion */
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(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(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         hammer_rel_volume(root_volume, 0);
173         return(error);
174 }
175