FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_disk.c
1 /*
2 * ----------------------------------------------------------------------------
3 * "THE BEER-WARE LICENSE" (Revision 42):
4 * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
5 * can do whatever you want with this stuff. If we meet some day, and you think
6 * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
7 * ----------------------------------------------------------------------------
8 */
9
10 #include <sys/cdefs.h>
11 __FBSDID("$FreeBSD: releng/5.3/sys/kern/subr_disk.c 136588 2004-10-16 08:43:07Z cvs2svn $");
12
13 #include "opt_geom.h"
14
15 #include <sys/param.h>
16 #include <sys/systm.h>
17 #include <sys/bio.h>
18 #include <sys/conf.h>
19 #include <sys/disk.h>
20 #include <geom/geom_disk.h>
21
22 /*-
23 * Disk error is the preface to plaintive error messages
24 * about failing disk transfers. It prints messages of the form
25 * "hp0g: BLABLABLA cmd=read fsbn 12345 of 12344-12347"
26 * blkdone should be -1 if the position of the error is unknown.
27 * The message is printed with printf.
28 */
29 void
30 disk_err(struct bio *bp, const char *what, int blkdone, int nl)
31 {
32 daddr_t sn;
33
34 if (bp->bio_dev != NULL)
35 printf("%s: %s ", devtoname(bp->bio_dev), what);
36 else if (bp->bio_disk != NULL)
37 printf("%s%d: %s ",
38 bp->bio_disk->d_name, bp->bio_disk->d_unit, what);
39 else
40 printf("disk??: %s ", what);
41 switch(bp->bio_cmd) {
42 case BIO_READ: printf("cmd=read "); break;
43 case BIO_WRITE: printf("cmd=write "); break;
44 case BIO_DELETE: printf("cmd=delete "); break;
45 case BIO_GETATTR: printf("cmd=getattr "); break;
46 default: printf("cmd=%x ", bp->bio_cmd); break;
47 }
48 sn = bp->bio_pblkno;
49 if (bp->bio_bcount <= DEV_BSIZE) {
50 printf("fsbn %jd%s", (intmax_t)sn, nl ? "\n" : "");
51 return;
52 }
53 if (blkdone >= 0) {
54 sn += blkdone;
55 printf("fsbn %jd of ", (intmax_t)sn);
56 }
57 printf("%jd-%jd", (intmax_t)bp->bio_pblkno,
58 (intmax_t)(bp->bio_pblkno + (bp->bio_bcount - 1) / DEV_BSIZE));
59 if (nl)
60 printf("\n");
61 }
62
63 /*
64 * BIO queue implementation
65 */
66
67 void
68 bioq_init(struct bio_queue_head *head)
69 {
70 TAILQ_INIT(&head->queue);
71 head->last_offset = 0;
72 head->insert_point = NULL;
73 head->switch_point = NULL;
74 }
75
76 void
77 bioq_remove(struct bio_queue_head *head, struct bio *bp)
78 {
79 if (bp == head->switch_point)
80 head->switch_point = TAILQ_NEXT(bp, bio_queue);
81 if (bp == head->insert_point) {
82 head->insert_point = TAILQ_PREV(bp, bio_queue, bio_queue);
83 if (head->insert_point == NULL)
84 head->last_offset = 0;
85 } else if (bp == TAILQ_FIRST(&head->queue))
86 head->last_offset = bp->bio_offset;
87 TAILQ_REMOVE(&head->queue, bp, bio_queue);
88 if (TAILQ_FIRST(&head->queue) == head->switch_point)
89 head->switch_point = NULL;
90 }
91
92 void
93 bioq_flush(struct bio_queue_head *head, struct devstat *stp, int error)
94 {
95 struct bio *bp;
96
97 for (;;) {
98 bp = bioq_first(head);
99 if (bp == NULL)
100 break;
101 bioq_remove(head, bp);
102 biofinish(bp, stp, error);
103 }
104 }
105
106 void
107 bioq_insert_tail(struct bio_queue_head *head, struct bio *bp)
108 {
109
110 TAILQ_INSERT_TAIL(&head->queue, bp, bio_queue);
111 }
112
113 struct bio *
114 bioq_first(struct bio_queue_head *head)
115 {
116
117 return (TAILQ_FIRST(&head->queue));
118 }
119
120
121 /*
122 * Seek sort for disks.
123 *
124 * The buf_queue keep two queues, sorted in ascending block order. The first
125 * queue holds those requests which are positioned after the current block
126 * (in the first request); the second, which starts at queue->switch_point,
127 * holds requests which came in after their block number was passed. Thus
128 * we implement a one way scan, retracting after reaching the end of the drive
129 * to the first request on the second queue, at which time it becomes the
130 * first queue.
131 *
132 * A one-way scan is natural because of the way UNIX read-ahead blocks are
133 * allocated.
134 */
135
136 void
137 bioq_disksort(bioq, bp)
138 struct bio_queue_head *bioq;
139 struct bio *bp;
140 {
141 struct bio *bq;
142 struct bio *bn;
143 struct bio *be;
144
145 be = TAILQ_LAST(&bioq->queue, bio_queue);
146 /*
147 * If the queue is empty or we are an
148 * ordered transaction, then it's easy.
149 */
150 if ((bq = bioq_first(bioq)) == NULL) {
151 bioq_insert_tail(bioq, bp);
152 return;
153 } else if (bioq->insert_point != NULL) {
154
155 /*
156 * A certain portion of the list is
157 * "locked" to preserve ordering, so
158 * we can only insert after the insert
159 * point.
160 */
161 bq = bioq->insert_point;
162 } else {
163
164 /*
165 * If we lie before the last removed (currently active)
166 * request, and are not inserting ourselves into the
167 * "locked" portion of the list, then we must add ourselves
168 * to the second request list.
169 */
170 if (bp->bio_offset < bioq->last_offset) {
171
172 bq = bioq->switch_point;
173 /*
174 * If we are starting a new secondary list,
175 * then it's easy.
176 */
177 if (bq == NULL) {
178 bioq->switch_point = bp;
179 bioq_insert_tail(bioq, bp);
180 return;
181 }
182 /*
183 * If we lie ahead of the current switch point,
184 * insert us before the switch point and move
185 * the switch point.
186 */
187 if (bp->bio_offset < bq->bio_offset) {
188 bioq->switch_point = bp;
189 TAILQ_INSERT_BEFORE(bq, bp, bio_queue);
190 return;
191 }
192 } else {
193 if (bioq->switch_point != NULL)
194 be = TAILQ_PREV(bioq->switch_point,
195 bio_queue, bio_queue);
196 /*
197 * If we lie between last_offset and bq,
198 * insert before bq.
199 */
200 if (bp->bio_offset < bq->bio_offset) {
201 TAILQ_INSERT_BEFORE(bq, bp, bio_queue);
202 return;
203 }
204 }
205 }
206
207 /*
208 * Request is at/after our current position in the list.
209 * Optimize for sequential I/O by seeing if we go at the tail.
210 */
211 if (bp->bio_offset > be->bio_offset) {
212 TAILQ_INSERT_AFTER(&bioq->queue, be, bp, bio_queue);
213 return;
214 }
215
216 /* Otherwise, insertion sort */
217 while ((bn = TAILQ_NEXT(bq, bio_queue)) != NULL) {
218
219 /*
220 * We want to go after the current request if it is the end
221 * of the first request list, or if the next request is a
222 * larger cylinder than our request.
223 */
224 if (bn == bioq->switch_point
225 || bp->bio_offset < bn->bio_offset)
226 break;
227 bq = bn;
228 }
229 TAILQ_INSERT_AFTER(&bioq->queue, bq, bp, bio_queue);
230 }
231
232
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