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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 1.10 2005/06/10 23:59:33 dillon Exp $
48 #ifndef _SYS_GLOBALDATA_H_
49 #include <sys/globaldata.h> /* curthread */
52 #ifndef _SYS_THREAD2_H_
53 #include <sys/thread2.h> /* crit_*() functions */
59 #define BUF_LOCKINIT(bp) \
60 lockinit(&(bp)->b_lock, 0, buf_wmesg, 0, 0)
64 * Get a lock sleeping non-interruptably until it becomes available.
67 BUF_LOCK(struct buf *bp, int locktype)
73 lwkt_gettoken(&ilock, &buftimetoken);
74 locktype |= LK_INTERLOCK;
75 bp->b_lock.lk_wmesg = buf_wmesg;
76 bp->b_lock.lk_prio = 0; /* tsleep flags */
77 /* bp->b_lock.lk_timo = 0; not necessary */
78 ret = lockmgr(&(bp)->b_lock, locktype, &ilock, curthread);
83 * Get a lock sleeping with specified interruptably and timeout.
86 BUF_TIMELOCK(struct buf *bp, int locktype, char *wmesg, int catch, int timo)
92 lwkt_gettoken(&ilock, &buftimetoken);
93 locktype |= LK_INTERLOCK | LK_TIMELOCK;
94 bp->b_lock.lk_wmesg = wmesg;
95 bp->b_lock.lk_prio = catch; /* tsleep flags */
96 bp->b_lock.lk_timo = timo;
97 ret = lockmgr(&(bp)->b_lock, locktype, &ilock, curthread);
102 * Release a lock. Only the acquiring process may free the lock unless
103 * it has been handed off to biodone.
106 BUF_UNLOCK(struct buf *bp)
109 lockmgr(&(bp)->b_lock, LK_RELEASE, NULL, curthread);
114 * When initiating asynchronous I/O, change ownership of the lock to the
115 * kernel. Once done, the lock may legally released by biodone. The
116 * original owning process can no longer acquire it recursively, but must
117 * wait until the I/O is completed and the lock has been freed by biodone.
120 BUF_KERNPROC(struct buf *bp)
122 struct thread *td = curthread;
124 if (bp->b_lock.lk_lockholder == td)
126 bp->b_lock.lk_lockholder = LK_KERNTHREAD;
129 * Find out the number of references to a lock.
131 * The non-blocking version should only be used for assertions in cases
132 * where the buffer is expected to be owned or otherwise data stable.
135 BUF_REFCNT(struct buf *bp)
140 ret = lockcount(&(bp)->b_lock);
146 BUF_REFCNTNB(struct buf *bp)
148 return (lockcountnb(&(bp)->b_lock));
152 * Free a buffer lock.
154 #define BUF_LOCKFREE(bp) \
155 if (BUF_REFCNTNB(bp) > 0) \
156 panic("free locked buf")
159 bufq_init(struct buf_queue_head *head)
161 TAILQ_INIT(&head->queue);
162 head->last_pblkno = 0;
163 head->insert_point = NULL;
164 head->switch_point = NULL;
168 bufq_insert_tail(struct buf_queue_head *head, struct buf *bp)
170 if ((bp->b_flags & B_ORDERED) != 0) {
171 head->insert_point = bp;
172 head->switch_point = NULL;
174 TAILQ_INSERT_TAIL(&head->queue, bp, b_act);
178 bufq_remove(struct buf_queue_head *head, struct buf *bp)
180 if (bp == head->switch_point)
181 head->switch_point = TAILQ_NEXT(bp, b_act);
182 if (bp == head->insert_point) {
183 head->insert_point = TAILQ_PREV(bp, buf_queue, b_act);
184 if (head->insert_point == NULL)
185 head->last_pblkno = 0;
186 } else if (bp == TAILQ_FIRST(&head->queue))
187 head->last_pblkno = bp->b_pblkno;
188 TAILQ_REMOVE(&head->queue, bp, b_act);
189 if (TAILQ_FIRST(&head->queue) == head->switch_point)
190 head->switch_point = NULL;
193 static __inline struct buf *
194 bufq_first(struct buf_queue_head *head)
196 return (TAILQ_FIRST(&head->queue));
201 #endif /* !_SYS_BUF2_H_ */