sys/sys/buf2.h

   1 /*
   2  * Copyright (c) 1982, 1986, 1989, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * (c) UNIX System Laboratories, Inc.
   5  * All or some portions of this file are derived from material licensed
   6  * to the University of California by American Telephone and Telegraph
   7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   8  * the permission of UNIX System Laboratories, Inc.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  *
  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 $
  41  */
  42
  43 #ifndef _SYS_BUF2_H_
  44 #define _SYS_BUF2_H_
  45
  46 #ifdef _KERNEL
  47
  48 #ifndef _SYS_BUF_H_
  49 #include <sys/buf.h>            /* crit_*() functions */
  50 #endif
  51 #ifndef _SYS_GLOBALDATA_H_
  52 #include <sys/globaldata.h>     /* curthread */
  53 #endif
  54 #ifndef _SYS_THREAD2_H_
  55 #include <sys/thread2.h>        /* crit_*() functions */
  56 #endif
  57 #ifndef _SYS_SPINLOCK2_H_
  58 #include <sys/spinlock2.h>      /* crit_*() functions */
  59 #endif
  60
  61 /*
  62  * Initialize a lock.
  63  */
  64 #define BUF_LOCKINIT(bp) \
  65         lockinit(&(bp)->b_lock, buf_wmesg, 0, 0)
  66
  67 /*
  68  *
  69  * Get a lock sleeping non-interruptably until it becomes available.
  70  *
  71  * XXX lk_wmesg can race, but should not result in any operational issues.
  72  */
  73 static __inline int
  74 BUF_LOCK(struct buf *bp, int locktype)
  75 {
  76         bp->b_lock.lk_wmesg = buf_wmesg;
  77         return (lockmgr(&(bp)->b_lock, locktype));
  78 }
  79 /*
  80  * Get a lock sleeping with specified interruptably and timeout.
  81  *
  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.
  85  *
  86  * XXX lk_wmesg can race, but should not result in any operational issues.
  87  */
  88 static __inline int
  89 BUF_TIMELOCK(struct buf *bp, int locktype, char *wmesg, int timo)
  90 {
  91         bp->b_lock.lk_wmesg = wmesg;
  92         bp->b_lock.lk_timo = timo;
  93         return (lockmgr(&(bp)->b_lock, locktype | LK_TIMELOCK));
  94 }
  95 /*
  96  * Release a lock. Only the acquiring process may free the lock unless
  97  * it has been handed off to biodone.
  98  */
  99 static __inline void
 100 BUF_UNLOCK(struct buf *bp)
 101 {
 102         lockmgr(&(bp)->b_lock, LK_RELEASE);
 103 }
 104
 105 /*
 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.
 110  */
 111 static __inline void
 112 BUF_KERNPROC(struct buf *bp)
 113 {
 114         lockmgr_kernproc(&(bp)->b_lock);
 115 }
 116 /*
 117  * Find out the number of references to a lock.
 118  *
 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.
 121  */
 122 static __inline int
 123 BUF_REFCNT(struct buf *bp)
 124 {
 125         return (lockcount(&(bp)->b_lock));
 126 }
 127
 128 static __inline int
 129 BUF_REFCNTNB(struct buf *bp)
 130 {
 131         return (lockcountnb(&(bp)->b_lock));
 132 }
 133
 134 /*
 135  * Free a buffer lock.
 136  */
 137 #define BUF_LOCKFREE(bp)                        \
 138         if (BUF_REFCNTNB(bp) > 0)               \
 139                 panic("free locked buf")
 140
 141 static __inline void
 142 bioq_init(struct bio_queue_head *head)
 143 {
 144         TAILQ_INIT(&head->queue);
 145         head->last_offset = 0;
 146         head->insert_point = NULL;
 147         head->switch_point = NULL;
 148 }
 149
 150 static __inline void
 151 bioq_insert_tail(struct bio_queue_head *head, struct bio *bio)
 152 {
 153         if ((bio->bio_buf->b_flags & B_ORDERED) != 0) {
 154                 head->insert_point = bio;
 155                 head->switch_point = NULL;
 156         }
 157         TAILQ_INSERT_TAIL(&head->queue, bio, bio_act);
 158 }
 159
 160 static __inline void
 161 bioq_remove(struct bio_queue_head *head, struct bio *bio)
 162 {
 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;
 174 }
 175
 176 static __inline struct bio *
 177 bioq_first(struct bio_queue_head *head)
 178 {
 179         return (TAILQ_FIRST(&head->queue));
 180 }
 181
 182 #endif /* _KERNEL */
 183
 184 #endif /* !_SYS_BUF2_H_ */