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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 1.7 2004/03/01 06:33:19 dillon Exp $
48 #ifndef _SYS_GLOBALDATA_H_
49 #include <sys/globaldata.h> /* curthread */
55 #define BUF_LOCKINIT(bp) \
56 lockinit(&(bp)->b_lock, 0, buf_wmesg, 0, 0)
60 * Get a lock sleeping non-interruptably until it becomes available.
62 static __inline int BUF_LOCK (struct buf *, int);
64 BUF_LOCK(struct buf *bp, int locktype)
70 lwkt_gettoken(&ilock, &buftimetoken);
71 locktype |= LK_INTERLOCK;
72 bp->b_lock.lk_wmesg = buf_wmesg;
73 bp->b_lock.lk_prio = 0; /* tsleep flags */
74 /* bp->b_lock.lk_timo = 0; not necessary */
75 ret = lockmgr(&(bp)->b_lock, locktype, &ilock, curthread);
80 * Get a lock sleeping with specified interruptably and timeout.
82 static __inline int BUF_TIMELOCK (struct buf *, int, char *, int, int);
84 BUF_TIMELOCK(struct buf *bp, int locktype, char *wmesg, int catch, int timo)
90 lwkt_gettoken(&ilock, &buftimetoken);
91 locktype |= LK_INTERLOCK | LK_TIMELOCK;
92 bp->b_lock.lk_wmesg = wmesg;
93 bp->b_lock.lk_prio = catch; /* tsleep flags */
94 bp->b_lock.lk_timo = timo;
95 ret = lockmgr(&(bp)->b_lock, locktype, &ilock, curthread);
100 * Release a lock. Only the acquiring process may free the lock unless
101 * it has been handed off to biodone.
103 static __inline void BUF_UNLOCK (struct buf *);
105 BUF_UNLOCK(struct buf *bp)
110 lockmgr(&(bp)->b_lock, LK_RELEASE, NULL, curthread);
115 * Free a buffer lock.
117 #define BUF_LOCKFREE(bp) \
118 if (BUF_REFCNT(bp) > 0) \
119 panic("free locked buf")
121 * When initiating asynchronous I/O, change ownership of the lock to the
122 * kernel. Once done, the lock may legally released by biodone. The
123 * original owning process can no longer acquire it recursively, but must
124 * wait until the I/O is completed and the lock has been freed by biodone.
126 static __inline void BUF_KERNPROC (struct buf *);
128 BUF_KERNPROC(struct buf *bp)
130 struct thread *td = curthread;
132 if (bp->b_lock.lk_lockholder == td)
134 bp->b_lock.lk_lockholder = LK_KERNTHREAD;
137 * Find out the number of references to a lock.
139 static __inline int BUF_REFCNT (struct buf *);
141 BUF_REFCNT(struct buf *bp)
146 ret = lockcount(&(bp)->b_lock);
152 bufq_init(struct buf_queue_head *head)
154 TAILQ_INIT(&head->queue);
155 head->last_pblkno = 0;
156 head->insert_point = NULL;
157 head->switch_point = NULL;
161 bufq_insert_tail(struct buf_queue_head *head, struct buf *bp)
163 if ((bp->b_flags & B_ORDERED) != 0) {
164 head->insert_point = bp;
165 head->switch_point = NULL;
167 TAILQ_INSERT_TAIL(&head->queue, bp, b_act);
171 bufq_remove(struct buf_queue_head *head, struct buf *bp)
173 if (bp == head->switch_point)
174 head->switch_point = TAILQ_NEXT(bp, b_act);
175 if (bp == head->insert_point) {
176 head->insert_point = TAILQ_PREV(bp, buf_queue, b_act);
177 if (head->insert_point == NULL)
178 head->last_pblkno = 0;
179 } else if (bp == TAILQ_FIRST(&head->queue))
180 head->last_pblkno = bp->b_pblkno;
181 TAILQ_REMOVE(&head->queue, bp, b_act);
182 if (TAILQ_FIRST(&head->queue) == head->switch_point)
183 head->switch_point = NULL;
186 static __inline struct buf *
187 bufq_first(struct buf_queue_head *head)
189 return (TAILQ_FIRST(&head->queue));
194 #endif /* !_SYS_BUF2_H_ */