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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 1.17 2006/05/05 20:15:01 dillon Exp $
48 #ifndef _SYS_GLOBALDATA_H_
49 #include <sys/globaldata.h> /* curthread */
51 #ifndef _SYS_THREAD2_H_
52 #include <sys/thread2.h> /* crit_*() functions */
54 #ifndef _SYS_SPINLOCK2_H_
55 #include <sys/spinlock2.h> /* crit_*() functions */
61 #define BUF_LOCKINIT(bp) \
62 lockinit(&(bp)->b_lock, buf_wmesg, 0, 0)
66 * Get a lock sleeping non-interruptably until it becomes available.
68 * XXX lk_wmesg can race, but should not result in any operational issues.
71 BUF_LOCK(struct buf *bp, int locktype)
73 bp->b_lock.lk_wmesg = buf_wmesg;
74 return (lockmgr(&(bp)->b_lock, locktype));
77 * Get a lock sleeping with specified interruptably and timeout.
79 * XXX lk_timo can race against other entities calling BUF_TIMELOCK,
80 * but will not interfere with entities calling BUF_LOCK since LK_TIMELOCK
81 * will not be set in that case.
83 * XXX lk_wmesg can race, but should not result in any operational issues.
86 BUF_TIMELOCK(struct buf *bp, int locktype, char *wmesg, int timo)
88 bp->b_lock.lk_wmesg = wmesg;
89 bp->b_lock.lk_timo = timo;
90 return (lockmgr(&(bp)->b_lock, locktype | LK_TIMELOCK));
93 * Release a lock. Only the acquiring process may free the lock unless
94 * it has been handed off to biodone.
97 BUF_UNLOCK(struct buf *bp)
99 lockmgr(&(bp)->b_lock, LK_RELEASE);
103 * When initiating asynchronous I/O, change ownership of the lock to the
104 * kernel. Once done, the lock may legally released by biodone. The
105 * original owning process can no longer acquire it recursively, but must
106 * wait until the I/O is completed and the lock has been freed by biodone.
109 BUF_KERNPROC(struct buf *bp)
111 lockmgr_kernproc(&(bp)->b_lock);
114 * Find out the number of references to a lock.
116 * The non-blocking version should only be used for assertions in cases
117 * where the buffer is expected to be owned or otherwise data stable.
120 BUF_REFCNT(struct buf *bp)
122 return (lockcount(&(bp)->b_lock));
126 BUF_REFCNTNB(struct buf *bp)
128 return (lockcountnb(&(bp)->b_lock));
132 * Free a buffer lock.
134 #define BUF_LOCKFREE(bp) \
135 if (BUF_REFCNTNB(bp) > 0) \
136 panic("free locked buf")
139 bioq_init(struct bio_queue_head *head)
141 TAILQ_INIT(&head->queue);
142 head->last_offset = 0;
143 head->insert_point = NULL;
144 head->switch_point = NULL;
148 bioq_insert_tail(struct bio_queue_head *head, struct bio *bio)
150 if ((bio->bio_buf->b_flags & B_ORDERED) != 0) {
151 head->insert_point = bio;
152 head->switch_point = NULL;
154 TAILQ_INSERT_TAIL(&head->queue, bio, bio_act);
158 bioq_remove(struct bio_queue_head *head, struct bio *bio)
160 if (bio == head->switch_point)
161 head->switch_point = TAILQ_NEXT(bio, bio_act);
162 if (bio == head->insert_point) {
163 head->insert_point = TAILQ_PREV(bio, bio_queue, bio_act);
164 if (head->insert_point == NULL)
165 head->last_offset = 0;
166 } else if (bio == TAILQ_FIRST(&head->queue))
167 head->last_offset = bio->bio_offset;
168 TAILQ_REMOVE(&head->queue, bio, bio_act);
169 if (TAILQ_FIRST(&head->queue) == head->switch_point)
170 head->switch_point = NULL;
173 static __inline struct bio *
174 bioq_first(struct bio_queue_head *head)
176 return (TAILQ_FIRST(&head->queue));
181 #endif /* !_SYS_BUF2_H_ */