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git.saurik.com Git - apple/xnu.git/blob - bsd/kern/subr_disk.c
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60 * @(#)ufs_disksubr.c 8.5 (Berkeley) 1/21/94
63 #include <sys/param.h>
64 #include <sys/systm.h>
66 #include <sys/disklabel.h>
67 #include <sys/syslog.h>
70 * Seek sort for disks. We depend on the driver which calls us using b_resid
71 * as the current cylinder number.
73 * The argument ap structure holds a b_actf activity chain pointer on which we
74 * keep two queues, sorted in ascending cylinder order. The first queue holds
75 * those requests which are positioned after the current cylinder (in the first
76 * request); the second holds requests which came in after their cylinder number
77 * was passed. Thus we implement a one way scan, retracting after reaching the
78 * end of the drive to the first request on the second queue, at which time it
79 * becomes the first queue.
81 * A one-way scan is natural because of the way UNIX read-ahead blocks are
86 * For portability with historic industry practice, the
87 * cylinder number has to be maintained in the `b_resid'
90 #define b_cylinder b_resid
94 register struct buf
*ap
, *bp
;
96 register struct buf
*bq
;
98 /* If the queue is empty, then it's easy. */
99 if (ap
->b_actf
== NULL
) {
106 * If we lie after the first (currently active) request, then we
107 * must locate the second request list and add ourselves to it.
110 if (bp
->b_cylinder
< bq
->b_cylinder
) {
113 * Check for an ``inversion'' in the normally ascending
114 * cylinder numbers, indicating the start of the second
117 if (bq
->b_actf
->b_cylinder
< bq
->b_cylinder
) {
119 * Search the second request list for the first
120 * request at a larger cylinder number. We go
121 * before that; if there is no such request, we
126 bq
->b_actf
->b_cylinder
)
128 if (bp
->b_cylinder
==
129 bq
->b_actf
->b_cylinder
&&
130 bp
->b_blkno
< bq
->b_actf
->b_blkno
)
133 } while (bq
->b_actf
);
134 goto insert
; /* after last */
139 * No inversions... we will go after the last, and
140 * be the first request in the second request list.
145 * Request is at/after the current request...
146 * sort in the first request list.
150 * We want to go after the current request if there is an
151 * inversion after it (i.e. it is the end of the first
152 * request list), or if the next request is a larger cylinder
155 if (bq
->b_actf
->b_cylinder
< bq
->b_cylinder
||
156 bp
->b_cylinder
< bq
->b_actf
->b_cylinder
||
157 (bp
->b_cylinder
== bq
->b_actf
->b_cylinder
&&
158 bp
->b_blkno
< bq
->b_actf
->b_blkno
))
163 * Neither a second list nor a larger request... we go at the end of
164 * the first list, which is the same as the end of the whole schebang.
166 insert
: bp
->b_actf
= bq
->b_actf
;
170 /* encoding of disk minor numbers, should be elsewhere... */
171 #define dkunit(dev) (minor(dev) >> 3)
172 #define dkpart(dev) (minor(dev) & 07)
173 #define dkminor(unit, part) (((unit) << 3) | (part))
176 * Compute checksum for disk label.
180 register struct disklabel
*lp
;
182 register u_short
*start
, *end
;
183 register u_short sum
= 0;
185 start
= (u_short
*)lp
;
186 end
= (u_short
*)&lp
->d_partitions
[lp
->d_npartitions
];
193 * Disk error is the preface to plaintive error messages
194 * about failing disk transfers. It prints messages of the form
196 hp0g: hard error reading fsbn 12345 of 12344-12347 (hp0 bn %d cn %d tn %d sn %d)
198 * if the offset of the error in the transfer and a disk label
199 * are both available. blkdone should be -1 if the position of the error
200 * is unknown; the disklabel pointer may be null from drivers that have not
201 * been converted to use them. The message is printed with printf
202 * if pri is LOG_PRINTF, otherwise it uses log at the specified priority.
203 * The message should be completed (with at least a newline) with printf
204 * or addlog, respectively. There is no trailing space.
207 diskerr(bp
, dname
, what
, pri
, blkdone
, lp
)
208 register struct buf
*bp
;
211 register struct disklabel
*lp
;
213 int unit
= dkunit(bp
->b_dev
), part
= dkpart(bp
->b_dev
);
214 register void (*pr
) __P((const char *, ...));
215 char partname
= 'a' + part
;
218 if (pri
!= LOG_PRINTF
) {
223 (*pr
)("%s%d%c: %s %sing fsbn ", dname
, unit
, partname
, what
,
224 bp
->b_flags
& B_READ
? "read" : "writ");
226 if (bp
->b_bcount
<= DEV_BSIZE
)
233 (*pr
)("%d-%d", bp
->b_blkno
,
234 bp
->b_blkno
+ (bp
->b_bcount
- 1) / DEV_BSIZE
);
236 if (lp
&& (blkdone
>= 0 || bp
->b_bcount
<= lp
->d_secsize
)) {
238 sn
*= DEV_BSIZE
/ lp
->d_secsize
; /* XXX */
240 sn
+= lp
->d_partitions
[part
].p_offset
;
241 (*pr
)(" (%s%d bn %d; cn %d", dname
, unit
, sn
,
242 sn
/ lp
->d_secpercyl
);
243 sn
%= lp
->d_secpercyl
;
244 (*pr
)(" tn %d sn %d)", sn
/ lp
->d_nsectors
, sn
% lp
->d_nsectors
);