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

     /*      $NetBSD: buf.h,v 1.80 2005/02/26 22:25:34 perry Exp $   */
     
     /*-
      * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
      * NASA Ames Research Center.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the NetBSD
     *      Foundation, Inc. and its contributors.
     * 4. Neither the name of The NetBSD Foundation nor the names of its
     *    contributors may be used to endorse or promote products derived
     *    from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     * POSSIBILITY OF SUCH DAMAGE.
     */
    
    /*
     * Copyright (c) 1982, 1986, 1989, 1993
     *      The Regents of the University of California.  All rights reserved.
     * (c) UNIX System Laboratories, Inc.
     * All or some portions of this file are derived from material licensed
     * to the University of California by American Telephone and Telegraph
     * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     * the permission of UNIX System Laboratories, Inc.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)buf.h       8.9 (Berkeley) 3/30/95
     */
    
    #ifndef _SYS_BUF_H_
    #define _SYS_BUF_H_
    
    #include <sys/pool.h>
    #include <sys/queue.h>
    #include <sys/lock.h>
    
    struct buf;
    struct mount;
    struct vnode;
    
    #define NOLIST ((struct buf *)0x87654321)
    
    /*
     * To avoid including <ufs/ffs/softdep.h>
     */
    LIST_HEAD(workhead, worklist);
    
    
    /*
     * These are currently used only by the soft dependency code, hence
     * are stored once in a global variable. If other subsystems wanted
     * to use these hooks, a pointer to a set of bio_ops could be added
     * to each buffer.
    */
   struct bio_ops {
           void    (*io_start)(struct buf *);
           void    (*io_complete)(struct buf *);
           void    (*io_deallocate)(struct buf *);
           int     (*io_fsync)(struct vnode *, int);
           int     (*io_sync)(struct mount *);
           void    (*io_movedeps)(struct buf *, struct buf *);
           int     (*io_countdeps)(struct buf *, int);
           void    (*io_pageiodone)(struct buf *);
   };
   
   /*
    * The buffer header describes an I/O operation in the kernel.
    */
   struct buf {
           TAILQ_ENTRY(buf) b_actq;        /* Device driver queue when active. */
           struct simplelock b_interlock;  /* Lock for b_flags changes */
           volatile int b_flags;           /* B_* flags. */
           int     b_error;                /* Errno value. */
           int     b_prio;                 /* Hint for buffer queue discipline. */
           int     b_bufsize;              /* Allocated buffer size. */
           int     b_bcount;               /* Valid bytes in buffer. */
           int     b_resid;                /* Remaining I/O. */
           dev_t   b_dev;                  /* Device associated with buffer. */
           struct {
                   caddr_t b_addr;         /* Memory, superblocks, indirect etc. */
           } b_un;
           daddr_t b_blkno;                /* Underlying physical block number
                                              (partition relative) */
           daddr_t b_rawblkno;             /* Raw underlying physical block
                                              number (not partition relative) */
                                           /* Function to call upon completion. */
           void    (*b_iodone)(struct buf *);
           struct  proc *b_proc;           /* Associated proc if B_PHYS set. */
           struct  vnode *b_vp;            /* File vnode. */
           struct  workhead b_dep;         /* List of filesystem dependencies. */
           void    *b_saveaddr;            /* Original b_addr for physio. */
   
           /*
            * private data for owner.
            *  - buffer cache buffers are owned by corresponding filesystem.
            *  - non-buffer cache buffers are owned by subsystem which
            *    allocated them. (filesystem, disk driver, etc)
            */
           union {
                   void *bf_private;
                   off_t bf_dcookie;       /* NFS: Offset cookie if dir block */
           } b_fspriv;
   #define b_private       b_fspriv.bf_private
   #define b_dcookie       b_fspriv.bf_dcookie
   
           /*
            * buffer cache specific data
            */
           LIST_ENTRY(buf) b_hash;         /* Hash chain. */
           LIST_ENTRY(buf) b_vnbufs;       /* Buffer's associated vnode. */
           TAILQ_ENTRY(buf) b_freelist;    /* Free list position if not active. */
           daddr_t b_lblkno;               /* Logical block number. */
           int b_freelistindex;            /* Free list index. (BQ_) */
   };
   
   #define BUF_INIT(bp)                                                    \
   do {                                                                    \
           LIST_INIT(&(bp)->b_dep);                                        \
           simple_lock_init(&(bp)->b_interlock);                           \
           (bp)->b_dev = NODEV;                                            \
           BIO_SETPRIO((bp), BPRIO_DEFAULT);                               \
   } while (/*CONSTCOND*/0)
   
   /*
    * For portability with historic industry practice, the cylinder number has
    * to be maintained in the `b_resid' field.
    */
   #define b_cylinder b_resid              /* Cylinder number for disksort(). */
   
   /* Device driver compatibility definitions. */
   #define b_data   b_un.b_addr            /* b_un.b_addr is not changeable. */
   
   /*
    * These flags are kept in b_flags.
    */
   #define B_AGE           0x00000001      /* Move to age queue when I/O done. */
   #define B_ASYNC         0x00000004      /* Start I/O, do not wait. */
   #define B_BAD           0x00000008      /* Bad block revectoring in progress. */
   #define B_BUSY          0x00000010      /* I/O in progress. */
   #define B_SCANNED       0x00000020      /* Block already pushed during sync */
   #define B_CALL          0x00000040      /* Call b_iodone from biodone. */
   #define B_DELWRI        0x00000080      /* Delay I/O until buffer reused. */
   #define B_DIRTY         0x00000100      /* Dirty page to be pushed out async. */
   #define B_DONE          0x00000200      /* I/O completed. */
   #define B_EINTR         0x00000400      /* I/O was interrupted */
   #define B_ERROR         0x00000800      /* I/O error occurred. */
   #define B_GATHERED      0x00001000      /* LFS: already in a segment. */
   #define B_INVAL         0x00002000      /* Does not contain valid info. */
   #define B_LOCKED        0x00004000      /* Locked in core (not reusable). */
   #define B_NOCACHE       0x00008000      /* Do not cache block after use. */
   #define B_CACHE         0x00020000      /* Bread found us in the cache. */
   #define B_PHYS          0x00040000      /* I/O to user memory. */
   #define B_RAW           0x00080000      /* Set by physio for raw transfers. */
   #define B_READ          0x00100000      /* Read buffer. */
   #define B_TAPE          0x00200000      /* Magnetic tape I/O. */
   #define B_WANTED        0x00800000      /* Process wants this buffer. */
   #define B_WRITE         0x00000000      /* Write buffer (pseudo flag). */
   #define B_XXX           0x02000000      /* Debugging flag. */
   #define B_VFLUSH        0x04000000      /* Buffer is being synced. */
   
   #define BUF_FLAGBITS \
       "\2\1AGE\3ASYNC\4BAD\5BUSY\6SCANNED\7CALL\10DELWRI" \
       "\11DIRTY\12DONE\13EINTR\14ERROR\15GATHERED\16INVAL\17LOCKED\20NOCACHE" \
       "\22CACHE\23PHYS\24RAW\25READ\26TAPE\30WANTED\32XXX\33VFLUSH"
   
   
   /*
    * This structure describes a clustered I/O.  It is stored in the b_saveaddr
    * field of the buffer on which I/O is done.  At I/O completion, cluster
    * callback uses the structure to parcel I/O's to individual buffers, and
    * then free's this structure.
    */
   struct cluster_save {
           long    bs_bcount;              /* Saved b_bcount. */
           long    bs_bufsize;             /* Saved b_bufsize. */
           void    *bs_saveaddr;           /* Saved b_addr. */
           int     bs_nchildren;           /* Number of associated buffers. */
           struct buf **bs_children;       /* List of associated buffers. */
   };
   
   /*
    * Zero out the buffer's data area.
    */
   #define clrbuf(bp)                                                      \
   do {                                                                    \
           memset((bp)->b_data, 0, (u_int)(bp)->b_bcount);                 \
           (bp)->b_resid = 0;                                              \
   } while (/* CONSTCOND */ 0)
   
   /* Flags to low-level allocation routines. */
   #define B_CLRBUF        0x01    /* Request allocated buffer be cleared. */
   #define B_SYNC          0x02    /* Do all allocations synchronously. */
   #define B_METAONLY      0x04    /* Return indirect block buffer. */
   
   #ifdef _KERNEL
   
   #define BIO_GETPRIO(bp)         ((bp)->b_prio)
   #define BIO_SETPRIO(bp, prio)   (bp)->b_prio = (prio)
   #define BIO_COPYPRIO(bp1, bp2)  BIO_SETPRIO(bp1, BIO_GETPRIO(bp2))
   
   #define BPRIO_NPRIO             3
   #define BPRIO_TIMECRITICAL      2
   #define BPRIO_TIMELIMITED       1
   #define BPRIO_TIMENONCRITICAL   0
   #define BPRIO_DEFAULT           BPRIO_TIMELIMITED
   
   extern  struct bio_ops bioops;
   extern  u_int nbuf;             /* The number of buffer headers */
   extern  struct buf *buf;        /* The buffer headers. */
   extern  char *buffers;          /* The buffer contents. */
   extern  u_int bufpages;         /* Number of memory pages in the buffer pool. */
   
   /*
    * Pool of I/O buffers.  Access to this pool must be protected with
    * splbio().
    */
   extern  struct pool bufpool;
   
   __BEGIN_DECLS
   void    allocbuf(struct buf *, int, int);
   void    bawrite(struct buf *);
   void    bdirty(struct buf *);
   void    bdwrite(struct buf *);
   void    biodone(struct buf *);
   int     biowait(struct buf *);
   int     bread(struct vnode *, daddr_t, int, struct ucred *, struct buf **);
   int     breada(struct vnode *, daddr_t, int, daddr_t, int, struct ucred *,
                  struct buf **);
   int     breadn(struct vnode *, daddr_t, int, daddr_t *, int *, int,
                  struct ucred *, struct buf **);
   void    brelse(struct buf *);
   void    bremfree(struct buf *);
   void    bufinit(void);
   int     bwrite(struct buf *);
   struct buf *getblk(struct vnode *, daddr_t, int, int, int);
   struct buf *geteblk(int);
   struct buf *getnewbuf(int, int, int);
   struct buf *incore(struct vnode *, daddr_t);
   
   void    minphys(struct buf *);
   int     physio(void (*)(struct buf *), struct buf *, dev_t, int,
                  void (*)(struct buf *), struct uio *);
   
   void    brelvp(struct buf *);
   void    reassignbuf(struct buf *, struct vnode *);
   void    bgetvp(struct vnode *, struct buf *);
   int     buf_syncwait(void);
   u_long  buf_memcalc(void);
   int     buf_drain(int);
   int     buf_setvalimit(vsize_t);
   #ifdef DDB
   void    vfs_buf_print(struct buf *, int, void (*)(const char *, ...));
   #endif
   
   __END_DECLS
   #endif
   #endif /* !_SYS_BUF_H_ */

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