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38 * @(#)buf.h 8.9 (Berkeley) 3/30/95
39 * $FreeBSD: src/sys/sys/buf.h,v 1.88.2.10 2003/01/25 19:02:23 dillon Exp $
40 * $DragonFly: src/sys/sys/buf2.h,v 1.18 2006/05/20 02:42:13 dillon Exp $
49 #include <sys/buf.h> /* crit_*() functions */
51 #ifndef _SYS_GLOBALDATA_H_
52 #include <sys/globaldata.h> /* curthread */
54 #ifndef _SYS_THREAD2_H_
55 #include <sys/thread2.h> /* crit_*() functions */
57 #ifndef _SYS_SPINLOCK2_H_
58 #include <sys/spinlock2.h> /* crit_*() functions */
64 #define BUF_LOCKINIT(bp) \
65 lockinit(&(bp)->b_lock, buf_wmesg, 0, 0)
69 * Get a lock sleeping non-interruptably until it becomes available.
71 * XXX lk_wmesg can race, but should not result in any operational issues.
74 BUF_LOCK(struct buf
*bp
, int locktype
)
76 bp
->b_lock
.lk_wmesg
= buf_wmesg
;
77 return (lockmgr(&(bp
)->b_lock
, locktype
));
80 * Get a lock sleeping with specified interruptably and timeout.
82 * XXX lk_timo can race against other entities calling BUF_TIMELOCK,
83 * but will not interfere with entities calling BUF_LOCK since LK_TIMELOCK
84 * will not be set in that case.
86 * XXX lk_wmesg can race, but should not result in any operational issues.
89 BUF_TIMELOCK(struct buf
*bp
, int locktype
, char *wmesg
, int timo
)
91 bp
->b_lock
.lk_wmesg
= wmesg
;
92 bp
->b_lock
.lk_timo
= timo
;
93 return (lockmgr(&(bp
)->b_lock
, locktype
| LK_TIMELOCK
));
96 * Release a lock. Only the acquiring process may free the lock unless
97 * it has been handed off to biodone.
100 BUF_UNLOCK(struct buf
*bp
)
102 lockmgr(&(bp
)->b_lock
, LK_RELEASE
);
106 * When initiating asynchronous I/O, change ownership of the lock to the
107 * kernel. Once done, the lock may legally released by biodone. The
108 * original owning process can no longer acquire it recursively, but must
109 * wait until the I/O is completed and the lock has been freed by biodone.
112 BUF_KERNPROC(struct buf
*bp
)
114 lockmgr_kernproc(&(bp
)->b_lock
);
117 * Find out the number of references to a lock.
119 * The non-blocking version should only be used for assertions in cases
120 * where the buffer is expected to be owned or otherwise data stable.
123 BUF_REFCNT(struct buf
*bp
)
125 return (lockcount(&(bp
)->b_lock
));
129 BUF_REFCNTNB(struct buf
*bp
)
131 return (lockcountnb(&(bp
)->b_lock
));
135 * Free a buffer lock.
137 #define BUF_LOCKFREE(bp) \
138 if (BUF_REFCNTNB(bp) > 0) \
139 panic("free locked buf")
142 bioq_init(struct bio_queue_head
*head
)
144 TAILQ_INIT(&head
->queue
);
145 head
->last_offset
= 0;
146 head
->insert_point
= NULL
;
147 head
->switch_point
= NULL
;
151 bioq_insert_tail(struct bio_queue_head
*head
, struct bio
*bio
)
153 if ((bio
->bio_buf
->b_flags
& B_ORDERED
) != 0) {
154 head
->insert_point
= bio
;
155 head
->switch_point
= NULL
;
157 TAILQ_INSERT_TAIL(&head
->queue
, bio
, bio_act
);
161 bioq_remove(struct bio_queue_head
*head
, struct bio
*bio
)
163 if (bio
== head
->switch_point
)
164 head
->switch_point
= TAILQ_NEXT(bio
, bio_act
);
165 if (bio
== head
->insert_point
) {
166 head
->insert_point
= TAILQ_PREV(bio
, bio_queue
, bio_act
);
167 if (head
->insert_point
== NULL
)
168 head
->last_offset
= 0;
169 } else if (bio
== TAILQ_FIRST(&head
->queue
))
170 head
->last_offset
= bio
->bio_offset
;
171 TAILQ_REMOVE(&head
->queue
, bio
, bio_act
);
172 if (TAILQ_FIRST(&head
->queue
) == head
->switch_point
)
173 head
->switch_point
= NULL
;
176 static __inline
struct bio
*
177 bioq_first(struct bio_queue_head
*head
)
179 return (TAILQ_FIRST(&head
->queue
));
184 #endif /* !_SYS_BUF2_H_ */