The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/buf.h

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    1 /*      $NetBSD: buf.h,v 1.72 2004/02/28 06:28:47 yamt Exp $    */
    2 
    3 /*-
    4  * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
    9  * NASA Ames Research Center.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 3. All advertising materials mentioning features or use of this software
   20  *    must display the following acknowledgement:
   21  *      This product includes software developed by the NetBSD
   22  *      Foundation, Inc. and its contributors.
   23  * 4. Neither the name of The NetBSD Foundation nor the names of its
   24  *    contributors may be used to endorse or promote products derived
   25  *    from this software without specific prior written permission.
   26  *
   27  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   28  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   29  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   30  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   31  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   37  * POSSIBILITY OF SUCH DAMAGE.
   38  */
   39 
   40 /*
   41  * Copyright (c) 1982, 1986, 1989, 1993
   42  *      The Regents of the University of California.  All rights reserved.
   43  * (c) UNIX System Laboratories, Inc.
   44  * All or some portions of this file are derived from material licensed
   45  * to the University of California by American Telephone and Telegraph
   46  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   47  * the permission of UNIX System Laboratories, Inc.
   48  *
   49  * Redistribution and use in source and binary forms, with or without
   50  * modification, are permitted provided that the following conditions
   51  * are met:
   52  * 1. Redistributions of source code must retain the above copyright
   53  *    notice, this list of conditions and the following disclaimer.
   54  * 2. Redistributions in binary form must reproduce the above copyright
   55  *    notice, this list of conditions and the following disclaimer in the
   56  *    documentation and/or other materials provided with the distribution.
   57  * 3. Neither the name of the University nor the names of its contributors
   58  *    may be used to endorse or promote products derived from this software
   59  *    without specific prior written permission.
   60  *
   61  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   62  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   63  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   64  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   65  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   66  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   67  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   68  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   69  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   70  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   71  * SUCH DAMAGE.
   72  *
   73  *      @(#)buf.h       8.9 (Berkeley) 3/30/95
   74  */
   75 
   76 #ifndef _SYS_BUF_H_
   77 #define _SYS_BUF_H_
   78 
   79 #include <sys/pool.h>
   80 #include <sys/queue.h>
   81 #include <sys/lock.h>
   82 
   83 struct buf;
   84 struct mount;
   85 struct vnode;
   86 
   87 #define NOLIST ((struct buf *)0x87654321)
   88 
   89 /*
   90  * To avoid including <ufs/ffs/softdep.h> 
   91  */   
   92 LIST_HEAD(workhead, worklist);
   93 
   94 /*
   95  * Device driver buffer queue.
   96  */
   97 struct bufq_state {
   98         void (*bq_put)(struct bufq_state *, struct buf *);
   99         struct buf *(*bq_get)(struct bufq_state *, int);
  100         void *bq_private;
  101         int bq_flags;                   /* Flags from bufq_alloc() */
  102 };
  103 
  104 /*
  105  * Flags for bufq_alloc.
  106  */
  107 #define BUFQ_SORT_RAWBLOCK      0x0001  /* Sort by b_rawblkno */
  108 #define BUFQ_SORT_CYLINDER      0x0002  /* Sort by b_cylinder, b_rawblkno */
  109 
  110 #define BUFQ_FCFS               0x0010  /* First-come first-serve */
  111 #define BUFQ_DISKSORT           0x0020  /* Min seek sort */
  112 #define BUFQ_READ_PRIO          0x0030  /* Min seek and read priority */
  113 #define BUFQ_PRIOCSCAN          0x0040  /* Per-priority CSCAN */
  114 
  115 #define BUFQ_SORT_MASK          0x000f
  116 #define BUFQ_METHOD_MASK        0x00f0
  117 
  118 #ifdef _KERNEL
  119 
  120 extern int bufq_disk_default_strat;
  121 #define BUFQ_DISK_DEFAULT_STRAT()       bufq_disk_default_strat
  122 void    bufq_alloc(struct bufq_state *, int);
  123 void    bufq_free(struct bufq_state *);
  124 
  125 #define BUFQ_PUT(bufq, bp) \
  126         (*(bufq)->bq_put)((bufq), (bp)) /* Put buffer in queue */
  127 #define BUFQ_GET(bufq) \
  128         (*(bufq)->bq_get)((bufq), 1)    /* Get and remove buffer from queue */
  129 #define BUFQ_PEEK(bufq) \
  130         (*(bufq)->bq_get)((bufq), 0)    /* Get buffer from queue */
  131 
  132 #endif /* _KERNEL */
  133 
  134 /*
  135  * These are currently used only by the soft dependency code, hence
  136  * are stored once in a global variable. If other subsystems wanted
  137  * to use these hooks, a pointer to a set of bio_ops could be added
  138  * to each buffer.
  139  */
  140 struct bio_ops {
  141         void    (*io_start)(struct buf *);
  142         void    (*io_complete)(struct buf *);
  143         void    (*io_deallocate)(struct buf *);
  144         int     (*io_fsync)(struct vnode *);
  145         int     (*io_sync)(struct mount *);
  146         void    (*io_movedeps)(struct buf *, struct buf *);
  147         int     (*io_countdeps)(struct buf *, int);
  148         void    (*io_pageiodone)(struct buf *);
  149 };
  150 
  151 /*
  152  * The buffer header describes an I/O operation in the kernel.
  153  */
  154 struct buf {
  155         TAILQ_ENTRY(buf) b_actq;        /* Device driver queue when active. */
  156         struct simplelock b_interlock;  /* Lock for b_flags changes */
  157         volatile long   b_flags;        /* B_* flags. */
  158         int     b_error;                /* Errno value. */
  159         int     b_prio;                 /* Hint for buffer queue discipline. */
  160         long    b_bufsize;              /* Allocated buffer size. */
  161         long    b_bcount;               /* Valid bytes in buffer. */
  162         long    b_resid;                /* Remaining I/O. */
  163         dev_t   b_dev;                  /* Device associated with buffer. */
  164         struct {
  165                 caddr_t b_addr;         /* Memory, superblocks, indirect etc. */
  166         } b_un;
  167         daddr_t b_blkno;                /* Underlying physical block number
  168                                            (partition relative) */
  169         daddr_t b_rawblkno;             /* Raw underlying physical block
  170                                            number (not partition relative) */
  171                                         /* Function to call upon completion. */
  172         void    (*b_iodone)(struct buf *);
  173         struct  proc *b_proc;           /* Associated proc if B_PHYS set. */
  174         struct  vnode *b_vp;            /* File vnode. */
  175         struct  workhead b_dep;         /* List of filesystem dependencies. */
  176         void    *b_saveaddr;            /* Original b_addr for physio. */
  177 
  178         /*
  179          * private data for owner.
  180          *  - buffer cache buffers are owned by corresponding filesystem.
  181          *  - non-buffer cache buffers are owned by subsystem which
  182          *    allocated them. (filesystem, disk driver, etc)
  183          */
  184         union {
  185                 void *bf_private;
  186                 off_t bf_dcookie;       /* NFS: Offset cookie if dir block */
  187         } b_fspriv;
  188 #define b_private       b_fspriv.bf_private
  189 #define b_dcookie       b_fspriv.bf_dcookie
  190 
  191         /*
  192          * buffer cache specific data
  193          */
  194         LIST_ENTRY(buf) b_hash;         /* Hash chain. */
  195         LIST_ENTRY(buf) b_vnbufs;       /* Buffer's associated vnode. */
  196         TAILQ_ENTRY(buf) b_freelist;    /* Free list position if not active. */
  197         daddr_t b_lblkno;               /* Logical block number. */
  198 };
  199 
  200 #define BUF_INIT(bp)                                                    \
  201 do {                                                                    \
  202         LIST_INIT(&(bp)->b_dep);                                        \
  203         simple_lock_init(&(bp)->b_interlock);                           \
  204         (bp)->b_dev = NODEV;                                            \
  205         BIO_SETPRIO((bp), BPRIO_DEFAULT);                               \
  206 } while (/*CONSTCOND*/0)
  207 
  208 /*
  209  * For portability with historic industry practice, the cylinder number has
  210  * to be maintained in the `b_resid' field.
  211  */
  212 #define b_cylinder b_resid              /* Cylinder number for disksort(). */
  213 
  214 /* Device driver compatibility definitions. */
  215 #define b_data   b_un.b_addr            /* b_un.b_addr is not changeable. */
  216 
  217 /*
  218  * These flags are kept in b_flags.
  219  */
  220 #define B_AGE           0x00000001      /* Move to age queue when I/O done. */
  221 #define B_ASYNC         0x00000004      /* Start I/O, do not wait. */
  222 #define B_BAD           0x00000008      /* Bad block revectoring in progress. */
  223 #define B_BUSY          0x00000010      /* I/O in progress. */
  224 #define B_SCANNED       0x00000020      /* Block already pushed during sync */
  225 #define B_CALL          0x00000040      /* Call b_iodone from biodone. */
  226 #define B_DELWRI        0x00000080      /* Delay I/O until buffer reused. */
  227 #define B_DIRTY         0x00000100      /* Dirty page to be pushed out async. */
  228 #define B_DONE          0x00000200      /* I/O completed. */
  229 #define B_EINTR         0x00000400      /* I/O was interrupted */
  230 #define B_ERROR         0x00000800      /* I/O error occurred. */
  231 #define B_GATHERED      0x00001000      /* LFS: already in a segment. */
  232 #define B_INVAL         0x00002000      /* Does not contain valid info. */
  233 #define B_LOCKED        0x00004000      /* Locked in core (not reusable). */
  234 #define B_NOCACHE       0x00008000      /* Do not cache block after use. */
  235 #define B_CACHE         0x00020000      /* Bread found us in the cache. */
  236 #define B_PHYS          0x00040000      /* I/O to user memory. */
  237 #define B_RAW           0x00080000      /* Set by physio for raw transfers. */
  238 #define B_READ          0x00100000      /* Read buffer. */
  239 #define B_TAPE          0x00200000      /* Magnetic tape I/O. */
  240 #define B_WANTED        0x00800000      /* Process wants this buffer. */
  241 #define B_WRITE         0x00000000      /* Write buffer (pseudo flag). */
  242 #define B_XXX           0x02000000      /* Debugging flag. */
  243 #define B_VFLUSH        0x04000000      /* Buffer is being synced. */
  244 
  245 /*
  246  * This structure describes a clustered I/O.  It is stored in the b_saveaddr
  247  * field of the buffer on which I/O is done.  At I/O completion, cluster
  248  * callback uses the structure to parcel I/O's to individual buffers, and
  249  * then free's this structure.
  250  */
  251 struct cluster_save {
  252         long    bs_bcount;              /* Saved b_bcount. */
  253         long    bs_bufsize;             /* Saved b_bufsize. */
  254         void    *bs_saveaddr;           /* Saved b_addr. */
  255         int     bs_nchildren;           /* Number of associated buffers. */
  256         struct buf **bs_children;       /* List of associated buffers. */
  257 };
  258 
  259 /*
  260  * Zero out the buffer's data area.
  261  */
  262 #define clrbuf(bp)                                                      \
  263 do {                                                                    \
  264         memset((bp)->b_data, 0, (u_int)(bp)->b_bcount);                 \
  265         (bp)->b_resid = 0;                                              \
  266 } while (/* CONSTCOND */ 0)
  267 
  268 /* Flags to low-level allocation routines. */
  269 #define B_CLRBUF        0x01    /* Request allocated buffer be cleared. */
  270 #define B_SYNC          0x02    /* Do all allocations synchronously. */
  271 
  272 #ifdef _KERNEL
  273 
  274 #define BIO_GETPRIO(bp)         ((bp)->b_prio)
  275 #define BIO_SETPRIO(bp, prio)   (bp)->b_prio = (prio)
  276 #define BIO_COPYPRIO(bp1, bp2)  BIO_SETPRIO(bp1, BIO_GETPRIO(bp2))
  277 
  278 #define BPRIO_NPRIO             3
  279 #define BPRIO_TIMECRITICAL      2
  280 #define BPRIO_TIMELIMITED       1
  281 #define BPRIO_TIMENONCRITICAL   0
  282 #define BPRIO_DEFAULT           BPRIO_TIMELIMITED
  283 
  284 extern  struct bio_ops bioops;
  285 extern  u_int nbuf;             /* The number of buffer headers */
  286 extern  struct buf *buf;        /* The buffer headers. */
  287 extern  char *buffers;          /* The buffer contents. */
  288 extern  u_int bufpages;         /* Number of memory pages in the buffer pool. */
  289 
  290 /*
  291  * Pool of I/O buffers.  Access to this pool must be protected with
  292  * splbio().
  293  */
  294 extern  struct pool bufpool;
  295 
  296 __BEGIN_DECLS
  297 void    allocbuf(struct buf *, int, int);
  298 void    bawrite(struct buf *);
  299 void    bdirty(struct buf *);
  300 void    bdwrite(struct buf *);
  301 void    biodone(struct buf *);
  302 int     biowait(struct buf *);
  303 int     bread(struct vnode *, daddr_t, int, struct ucred *, struct buf **);
  304 int     breada(struct vnode *, daddr_t, int, daddr_t, int, struct ucred *,
  305                struct buf **);
  306 int     breadn(struct vnode *, daddr_t, int, daddr_t *, int *, int,
  307                struct ucred *, struct buf **);
  308 void    brelse(struct buf *);
  309 void    bremfree(struct buf *);
  310 void    bufinit(void);
  311 int     bwrite(struct buf *);
  312 struct buf *getblk(struct vnode *, daddr_t, int, int, int);
  313 struct buf *geteblk(int);
  314 struct buf *getnewbuf(int, int, int);
  315 struct buf *incore(struct vnode *, daddr_t);
  316 
  317 void    minphys(struct buf *);
  318 int     physio(void (*)(struct buf *), struct buf *, dev_t, int,
  319                void (*)(struct buf *), struct uio *);
  320 
  321 void    brelvp(struct buf *);
  322 void    reassignbuf(struct buf *, struct vnode *);
  323 void    bgetvp(struct vnode *, struct buf *);
  324 int     buf_syncwait(void);
  325 u_long  buf_memcalc(void);
  326 int     buf_drain(int);
  327 int     buf_setvalimit(vsize_t);
  328 #ifdef DDB
  329 void    vfs_buf_print(struct buf *, int, void (*)(const char *, ...));
  330 #endif
  331 __END_DECLS
  332 #endif
  333 #endif /* !_SYS_BUF_H_ */

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