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

     /*     $NetBSD: buf.h,v 1.110 2008/07/31 05:38:05 simonb Exp $ */
     
     /*-
      * Copyright (c) 1999, 2000, 2007 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, and by Andrew Doran.
     *
     * 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.
     *
     * 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/mutex.h>
    #include <sys/condvar.h>
    #if defined(_KERNEL)
    #include <sys/workqueue.h>
    #endif /* defined(_KERNEL) */
    
    struct buf;
    struct mount;
    struct vnode;
    struct kauth_cred;
    
    #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 *);
   };
   
   extern kmutex_t bufcache_lock;
   extern kmutex_t buffer_lock;
   
   /*
    * The buffer header describes an I/O operation in the kernel.
    *
    * Field markings and the corresponding locks:
    *
    * b    thread of execution that holds BC_BUSY, does not correspond
    *        directly to any particular LWP
    * c    bufcache_lock
    * l    b_objlock
    *
    * For buffers associated with a vnode, b_objlock points to vp->v_interlock.
    * If not associated with a vnode, it points to the generic buffer_lock.
    */
   struct buf {
           union {
                   TAILQ_ENTRY(buf) u_actq;
   #if defined(_KERNEL) /* u_work is smaller than u_actq. XXX */
                   struct work u_work;
   #endif /* defined(_KERNEL) */
           } b_u;                                  /* b: device driver queue */
   #define b_actq  b_u.u_actq
   #define b_work  b_u.u_work
           void                    (*b_iodone)(struct buf *);/* b: call when done */
           int                     b_error;        /* b: errno value. */
           int                     b_resid;        /* b: remaining I/O. */
           u_int                   b_flags;        /* b: B_* flags */
           int                     b_prio;         /* b: priority for queue */
           int                     b_bufsize;      /* b: allocated size */
           int                     b_bcount;       /* b: valid bytes in buffer */
           dev_t                   b_dev;          /* b: associated device */
           void                    *b_data;        /* b: fs private data */
           daddr_t                 b_blkno;        /* b: physical block number
                                                         (partition relative) */
           daddr_t                 b_rawblkno;     /* b: raw physical block number
                                                         (volume relative) */
           struct proc             *b_proc;        /* b: proc if BB_PHYS */
           void                    *b_saveaddr;    /* b: saved b_data for physio */
   
           /*
            * b: 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)
            */
           void    *b_private;
           off_t   b_dcookie;              /* NFS: Offset cookie if dir block */
   
           kcondvar_t              b_busy;         /* c: threads waiting on buf */
           u_int                   b_refcnt;       /* c: refcount for b_busy */
           struct workhead         b_dep;          /* c: softdep */
           LIST_ENTRY(buf)         b_hash;         /* c: hash chain */
           LIST_ENTRY(buf)         b_vnbufs;       /* c: associated vnode */
           TAILQ_ENTRY(buf)        b_freelist;     /* c: position if not active */
           LIST_ENTRY(buf)         b_wapbllist;    /* c: transaction buffer list */
           daddr_t                 b_lblkno;       /* c: logical block number */
           int                     b_freelistindex;/* c: free list index (BQ_) */
           u_int                   b_cflags;       /* c: BC_* flags */
           struct vnode            *b_vp;          /* c: file vnode */
   
           kcondvar_t              b_done;         /* o: waiting on completion */
           u_int                   b_oflags;       /* o: BO_* flags */
           kmutex_t                *b_objlock;     /* o: completion lock */
   };
   
   /*
    * 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(). */
   
   /*
    * These flags are kept in b_cflags (owned by buffer cache).
    */
   #define BC_AGE          0x00000001      /* Move to age queue when I/O done. */
   #define BC_BUSY         0x00000010      /* I/O in progress. */
   #define BC_SCANNED      0x00000020      /* Block already pushed during sync */
   #define BC_INVAL        0x00002000      /* Does not contain valid info. */
   #define BC_NOCACHE      0x00008000      /* Do not cache block after use. */
   #define BC_WANTED       0x00800000      /* Process wants this buffer. */
   #define BC_VFLUSH       0x04000000      /* Buffer is being synced. */
   
   /*
    * These flags are kept in b_oflags (owned by associated object).
    */
   #define BO_DELWRI       0x00000080      /* Delay I/O until buffer reused. */
   #define BO_DONE         0x00000200      /* I/O completed. */
   
   /*
    * These flags are kept in b_flags (owned by buffer holder).
    */
   #define B_WRITE         0x00000000      /* Write buffer (pseudo flag). */
   #define B_ASYNC         0x00000004      /* Start I/O, do not wait. */
   #define B_COWDONE       0x00000400      /* Copy-on-write already done. */
   #define B_GATHERED      0x00001000      /* LFS: already in a segment. */
   #define B_LOCKED        0x00004000      /* Locked in core (not reusable). */
   #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_DEVPRIVATE    0x02000000      /* Device driver private flag. */
   
   #define BUF_FLAGBITS \
       "\2\1AGE\3ASYNC\4BAD\5BUSY\6SCANNED\10DELWRI" \
       "\12DONE\13COWDONE\15GATHERED\16INVAL\17LOCKED\20NOCACHE" \
       "\23PHYS\24RAW\25READ\32DEVPRIVATE\33VFLUSH"
   
   /* Avoid weird code due to B_WRITE being a "pseudo flag" */
   #define BUF_ISREAD(bp)  (((bp)->b_flags & B_READ) == B_READ)
   #define BUF_ISWRITE(bp) (((bp)->b_flags & B_READ) == B_WRITE)
   
   /*
    * 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. */
   #define B_CONTIG        0x08    /* Allocate file contiguously. */
   
   /* Flags to bread(), breadn() and breada(). */
   #define B_MODIFY        0x01    /* Hint: caller might modify 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  const struct bio_ops *bioopsp;
   extern  u_int nbuf;             /* The number of buffer headers */
   
   /*
    * Definitions for the buffer free lists.
    */
   #define BQUEUES         4               /* number of free buffer queues */
   
   #define BQ_LOCKED       0               /* super-blocks &c */
   #define BQ_LRU          1               /* lru, useful buffers */
   #define BQ_AGE          2               /* rubbish */
   #define BQ_EMPTY        3               /* buffer headers with no memory */
   
   struct bqueue {
           TAILQ_HEAD(, buf) bq_queue;
           uint64_t bq_bytes;
           buf_t *bq_marker;
   };
   
   extern struct bqueue bufqueues[BQUEUES];
   extern struct simplelock bqueue_slock;
   
   __BEGIN_DECLS
   int     allocbuf(buf_t *, int, int);
   void    bawrite(buf_t *);
   void    bdirty(buf_t *);
   void    bdwrite(buf_t *);
   void    biodone(buf_t *);
   int     biowait(buf_t *);
   int     bread(struct vnode *, daddr_t, int, struct kauth_cred *, int, buf_t **);
   int     breada(struct vnode *, daddr_t, int, daddr_t, int, struct kauth_cred *,
                  int, buf_t **);
   int     breadn(struct vnode *, daddr_t, int, daddr_t *, int *, int,
                  struct kauth_cred *, int, buf_t **);
   void    brelsel(buf_t *, int);
   void    brelse(buf_t *, int);
   void    bremfree(buf_t *);
   void    bufinit(void);
   void    bufinit2(void);
   int     bwrite(buf_t *);
   buf_t   *getblk(struct vnode *, daddr_t, int, int, int);
   buf_t   *geteblk(int);
   buf_t   *incore(struct vnode *, daddr_t);
   
   void    minphys(buf_t *);
   int     physio(void (*)(buf_t *), buf_t *, dev_t, int,
                  void (*)(buf_t *), struct uio *);
   
   void    brelvp(buf_t *);
   void    reassignbuf(buf_t *, struct vnode *);
   void    bgetvp(struct vnode *, buf_t *);
   int     buf_syncwait(void);
   u_long  buf_memcalc(void);
   int     buf_drain(int);
   int     buf_setvalimit(vsize_t);
   #ifdef DDB
   void    vfs_buf_print(buf_t *, int, void (*)(const char *, ...));
   #endif
   buf_t   *getiobuf(struct vnode *, bool);
   void    putiobuf(buf_t *);
   void    buf_init(buf_t *);
   void    buf_destroy(buf_t *);
   int     bbusy(buf_t *, bool, int, kmutex_t *);
   
   void    nestiobuf_iodone(buf_t *);
   void    nestiobuf_setup(buf_t *, buf_t *, int, size_t);
   void    nestiobuf_done(buf_t *, int, int);
   
   __END_DECLS
   #endif /* _KERNEL */
   #endif /* !_SYS_BUF_H_ */

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