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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 1.14 2006/03/02 19:26:17 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, NULL, curthread));
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,
94 * Release a lock. Only the acquiring process may free the lock unless
95 * it has been handed off to biodone.
98 BUF_UNLOCK(struct buf *bp)
100 lockmgr(&(bp)->b_lock, LK_RELEASE, NULL, curthread);
104 * When initiating asynchronous I/O, change ownership of the lock to the
105 * kernel. Once done, the lock may legally released by biodone. The
106 * original owning process can no longer acquire it recursively, but must
107 * wait until the I/O is completed and the lock has been freed by biodone.
110 BUF_KERNPROC(struct buf *bp)
112 struct thread *td = curthread;
114 if (bp->b_lock.lk_lockholder == td)
116 bp->b_lock.lk_lockholder = LK_KERNTHREAD;
119 * Find out the number of references to a lock.
121 * The non-blocking version should only be used for assertions in cases
122 * where the buffer is expected to be owned or otherwise data stable.
125 BUF_REFCNT(struct buf *bp)
127 return (lockcount(&(bp)->b_lock));
131 BUF_REFCNTNB(struct buf *bp)
133 return (lockcountnb(&(bp)->b_lock));
137 * Free a buffer lock.
139 #define BUF_LOCKFREE(bp) \
140 if (BUF_REFCNTNB(bp) > 0) \
141 panic("free locked buf")
144 bioq_init(struct bio_queue_head *head)
146 TAILQ_INIT(&head->queue);
147 head->last_blkno = 0;
148 head->insert_point = NULL;
149 head->switch_point = NULL;
153 bioq_insert_tail(struct bio_queue_head *head, struct bio *bio)
155 if ((bio->bio_buf->b_flags & B_ORDERED) != 0) {
156 head->insert_point = bio;
157 head->switch_point = NULL;
159 TAILQ_INSERT_TAIL(&head->queue, bio, bio_act);
163 bioq_remove(struct bio_queue_head *head, struct bio *bio)
165 if (bio == head->switch_point)
166 head->switch_point = TAILQ_NEXT(bio, bio_act);
167 if (bio == head->insert_point) {
168 head->insert_point = TAILQ_PREV(bio, bio_queue, bio_act);
169 if (head->insert_point == NULL)
170 head->last_blkno = 0;
171 } else if (bio == TAILQ_FIRST(&head->queue))
172 head->last_blkno = bio->bio_blkno;
173 TAILQ_REMOVE(&head->queue, bio, bio_act);
174 if (TAILQ_FIRST(&head->queue) == head->switch_point)
175 head->switch_point = NULL;
178 static __inline struct bio *
179 bioq_first(struct bio_queue_head *head)
181 return (TAILQ_FIRST(&head->queue));
186 #endif /* !_SYS_BUF2_H_ */