bsd/sys/buf.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
  23 /*
  24  * Copyright (c) 1982, 1986, 1989, 1993
  25  *      The Regents of the University of California.  All rights reserved.
  26  * (c) UNIX System Laboratories, Inc.
  27  * All or some portions of this file are derived from material licensed
  28  * to the University of California by American Telephone and Telegraph
  29  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  30  * the permission of UNIX System Laboratories, Inc.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  *
  60  *      @(#)buf.h       8.9 (Berkeley) 3/30/95
  61  */
  62
  63 #ifndef _SYS_BUF_H_
  64 #define _SYS_BUF_H_
  65 #include <sys/queue.h>
  66 #include <sys/errno.h>
  67
  68 #include <sys/vm.h>
  69
  70 #define NOLIST ((struct buf *)0x87654321)
  71
  72 #include <sys/cdefs.h>
  73
  74 /*
  75  * The buffer header describes an I/O operation in the kernel.
  76  */
  77 struct buf {
  78         LIST_ENTRY(buf) b_hash;         /* Hash chain. */
  79         LIST_ENTRY(buf) b_vnbufs;       /* Buffer's associated vnode. */
  80         TAILQ_ENTRY(buf) b_freelist;    /* Free list position if not active. */
  81         struct  proc *b_proc;           /* Associated proc; NULL if kernel. */
  82         volatile long   b_flags;        /* B_* flags. */
  83         int     b_error;                /* Errno value. */
  84         long    b_bufsize;              /* Allocated buffer size. */
  85         long    b_bcount;               /* Valid bytes in buffer. */
  86         long    b_resid;                /* Remaining I/O. */
  87         dev_t   b_dev;                  /* Device associated with buffer. */
  88         struct {
  89                 caddr_t b_addr;         /* Memory, superblocks, indirect etc.*/
  90         } b_un;
  91         void    *b_saveaddr;            /* Original b_addr for physio. */
  92         daddr_t b_lblkno;               /* Logical block number. */
  93         daddr_t b_blkno;                /* Underlying physical block number. */
  94                                         /* Function to call upon completion. */
  95         void    (*b_iodone) __P((struct buf *));
  96         struct  vnode *b_vp;            /* Device vnode. */
  97         int     b_dirtyoff;             /* Offset in buffer of dirty region. */
  98         int     b_dirtyend;             /* Offset of end of dirty region. */
  99         int     b_validoff;             /* Offset in buffer of valid region. */
 100         int     b_validend;             /* Offset of end of valid region. */
 101         struct  ucred *b_rcred;         /* Read credentials reference. */
 102         struct  ucred *b_wcred;         /* Write credentials reference. */
 103         int     b_timestamp;            /* timestamp for queuing operation */
 104         long    b_vectorcount;  /* number of vectors in b_vectorlist */
 105         void    *b_vectorlist;  /* vector list for I/O */
 106         void    *b_pagelist;    /* to save pagelist info */
 107         long    b_vects[2];             /* vectorlist when b_vectorcount is 1 */
 108         long    b_whichq;               /* the free list the buffer belongs to */
 109         TAILQ_ENTRY(buf)        b_act;  /* Device driver queue when active */
 110         void    *b_drvdata;             /* Device driver private use */
 111 };
 112
 113 /*
 114  * For portability with historic industry practice, the cylinder number has
 115  * to be maintained in the `b_resid' field.
 116  */
 117 #define b_cylinder b_resid              /* Cylinder number for disksort(). */
 118
 119 /* Device driver compatibility definitions. */
 120 #define b_active b_bcount               /* Driver queue head: drive active. */
 121 #define b_data   b_un.b_addr            /* b_un.b_addr is not changeable. */
 122 #define b_errcnt b_resid                /* Retry count while I/O in progress. */
 123 #define iodone   biodone                /* Old name for biodone. */
 124 #define iowait   biowait                /* Old name for biowait. */
 125
 126 /* cluster_io definitions for use with io bufs */
 127 #define b_uploffset  b_bufsize
 128 #define b_trans_head b_freelist.tqe_prev
 129 #define b_trans_next b_freelist.tqe_next
 130 #define b_real_bp    b_saveaddr
 131
 132 /*
 133  * These flags are kept in b_flags.
 134  */
 135 #define B_AGE           0x00000001      /* Move to age queue when I/O done. */
 136 #define B_NEEDCOMMIT    0x00000002      /* Append-write in progress. */
 137 #define B_ASYNC         0x00000004      /* Start I/O, do not wait. */
 138 #define B_BAD           0x00000008      /* Bad block revectoring in progress. */
 139 #define B_BUSY          0x00000010      /* I/O in progress. */
 140 #define B_CACHE         0x00000020      /* Bread found us in the cache. */
 141 #define B_CALL          0x00000040      /* Call b_iodone from biodone. */
 142 #define B_DELWRI        0x00000080      /* Delay I/O until buffer reused. */
 143 #define B_DIRTY         0x00000100      /* Dirty page to be pushed out async. */
 144 #define B_DONE          0x00000200      /* I/O completed. */
 145 #define B_EINTR         0x00000400      /* I/O was interrupted */
 146 #define B_ERROR         0x00000800      /* I/O error occurred. */
 147 #define B_WASDIRTY      0x00001000      /* page was found dirty in the VM cache */
 148 #define B_INVAL         0x00002000      /* Does not contain valid info. */
 149 #define B_LOCKED        0x00004000      /* Locked in core (not reusable). */
 150 #define B_NOCACHE       0x00008000      /* Do not cache block after use. */
 151 #define B_PAGEOUT       0x00010000      /* Page out indicator... */
 152 #define B_PGIN          0x00020000      /* Pagein op, so swap() can count it. */
 153 #define B_PHYS          0x00040000      /* I/O to user memory. */
 154 #define B_RAW           0x00080000      /* Set by physio for raw transfers. */
 155 #define B_READ          0x00100000      /* Read buffer. */
 156 #define B_TAPE          0x00200000      /* Magnetic tape I/O. */
 157 #define B_PAGELIST      0x00400000      /* Buffer describes pagelist I/O. */
 158 #define B_WANTED        0x00800000      /* Process wants this buffer. */
 159 #define B_WRITE         0x00000000      /* Write buffer (pseudo flag). */
 160 #define B_WRITEINPROG   0x01000000      /* Write in progress. */
 161 #define B_UNUSED0       0x02000000      /* Unused bit */
 162 #define B_UNUSED1       0x04000000      /* Unused bit */
 163 #define B_NEED_IODONE   0x08000000
 164                                                                 /* need to do a biodone on the */
 165                                                                 /* real_bp associated with a cluster_io */
 166 #define B_COMMIT_UPL    0x10000000
 167                                                                 /* commit pages in upl when */
 168                                                                 /* I/O completes/fails */
 169 #define B_ZALLOC        0x20000000      /* b_data is zalloc()ed */
 170 #define B_META          0x40000000      /* buffer contains meta-data. */
 171 #define B_VECTORLIST    0x80000000      /* Used by device drivers. */
 172
 173
 174 /*
 175  * Zero out the buffer's data area.
 176  */
 177 #define clrbuf(bp) {                                                    \
 178         bzero((bp)->b_data, (u_int)(bp)->b_bcount);                     \
 179         (bp)->b_resid = 0;                                              \
 180 }
 181
 182 /* Flags to low-level allocation routines. */
 183 #define B_CLRBUF        0x01    /* Request allocated buffer be cleared. */
 184 #define B_SYNC          0x02    /* Do all allocations synchronously. */
 185 #define B_NOBUFF        0x04    /* Do not allocate struct buf */
 186
 187 /* Flags for operation type in getblk() */
 188 #define BLK_READ        0x01    /* buffer for read */
 189 #define BLK_WRITE       0x02    /* buffer for write */
 190 #define BLK_PAGEIN      0x04    /* buffer for pagein */
 191 #define BLK_PAGEOUT     0x08    /* buffer for pageout */
 192 #define BLK_META        0x10    /* buffer for metadata */
 193 #define BLK_CLREAD      0x20    /* buffer for cluster read */
 194 #define BLK_CLWRITE     0x40    /* buffer for cluster write */
 195
 196 #ifdef KERNEL
 197 extern int nbuf;                        /* The number of buffer headers */
 198 extern struct buf *buf;         /* The buffer headers. */
 199
 200 /* Macros to clear/set/test flags. */
 201 #define SET(t, f)       (t) |= (f)
 202 #define CLR(t, f)       (t) &= ~(f)
 203 #define ISSET(t, f)     ((t) & (f))
 204
 205 /*
 206  * Definitions for the buffer free lists.
 207  */
 208 #define BQUEUES         5               /* number of free buffer queues */
 209
 210 #define BQ_LOCKED       0               /* super-blocks &c */
 211 #define BQ_LRU          1               /* lru, useful buffers */
 212 #define BQ_AGE          2               /* rubbish */
 213 #define BQ_EMPTY        3               /* buffer headers with no memory */
 214 #define BQ_META         4               /* buffer containing metadata */
 215
 216 __BEGIN_DECLS
 217 int     allocbuf __P((struct buf *, int));
 218 void    bawrite __P((struct buf *));
 219 void    bdwrite __P((struct buf *));
 220 void    biodone __P((struct buf *));
 221 int     biowait __P((struct buf *));
 222 int     bread __P((struct vnode *, daddr_t, int,
 223             struct ucred *, struct buf **));
 224 int     meta_bread __P((struct vnode *, daddr_t, int,
 225             struct ucred *, struct buf **));
 226 int     breada __P((struct vnode *, daddr_t, int, daddr_t, int,
 227             struct ucred *, struct buf **));
 228 int     breadn __P((struct vnode *, daddr_t, int, daddr_t *, int *, int,
 229             struct ucred *, struct buf **));
 230 void    brelse __P((struct buf *));
 231 void    bremfree __P((struct buf *));
 232 void    bufinit __P((void));
 233 int     bwrite __P((struct buf *));
 234 struct buf *getblk __P((struct vnode *, daddr_t, int, int, int, int));
 235 struct buf *geteblk __P((int));
 236 struct buf *incore __P((struct vnode *, daddr_t));
 237 u_int   minphys __P((struct buf *bp));
 238 int physio __P((void (*)(struct buf *), struct buf *, dev_t, int ,  u_int (*)(struct buf *), struct uio *, int ));
 239 int count_busy_buffers __P((void));
 240 struct buf *alloc_io_buf __P((struct vnode *vp));
 241 void free_io_buf __P((struct buf *bp));
 242 __END_DECLS
 243
 244 /*
 245  *      Stats on usefulness of the buffer cache
 246  */
 247 struct bufstats {
 248         long    bufs_incore;            /* found incore */
 249         long    bufs_busyincore;        /* found incore. was busy */
 250         long    bufs_vmhits;            /* not incore. found in VM */
 251         long    bufs_miss;                      /* not incore. not in VM */
 252         long    bufs_sleeps;            /* buffer starvation */
 253         long    bufs_eblk;                      /* Calls to geteblk */
 254         long    bufs_iobufmax;          /* Max. number of IO buffers used */
 255         long    bufs_iobufinuse;        /* number of IO buffers in use */
 256         long    bufs_iobufsleeps;       /* IO buffer starvation */
 257 };
 258
 259 #endif /* KERNEL */
 260 #endif /* !_SYS_BUF_H_ */