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

     /*
      * 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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. 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
     * $FreeBSD$
     */
    
    #ifndef _SYS_BUF_H_
    #define _SYS_BUF_H_
    
    #include <sys/queue.h>
    
    struct buf;
    struct mount;
    struct vnode;
    
    /*
     * 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.
     */
    extern struct bio_ops {
            void    (*io_start) __P((struct buf *));
            void    (*io_complete) __P((struct buf *));
            void    (*io_deallocate) __P((struct buf *));
            int     (*io_fsync) __P((struct vnode *));
            int     (*io_sync) __P((struct mount *));
    } bioops;
    
    struct iodone_chain {
            long    ic_prev_flags;
            void    (*ic_prev_iodone) __P((struct buf *));
            void    *ic_prev_iodone_chain;
            struct {
                    long    ia_long;
                    void    *ia_ptr;
            }       ic_args[5];
    };
    
    /*
     * The buffer header describes an I/O operation in the kernel.
     */
    struct buf {
            LIST_ENTRY(buf) b_hash;         /* Hash chain. */
            TAILQ_ENTRY(buf) b_vnbufs;      /* Buffer's associated vnode. */
            TAILQ_ENTRY(buf) b_freelist;    /* Free list position if not active. */
            TAILQ_ENTRY(buf) b_act;         /* Device driver queue when active. *new* */
            struct  proc *b_proc;           /* Associated proc; NULL if kernel. */
            long    b_flags;                /* B_* flags. */
            unsigned short b_qindex;        /* buffer queue index */
            unsigned char b_usecount;       /* buffer use count */
            unsigned char b_xflags;         /* extra flags */
            int     b_error;                /* Errno value. */
            long    b_bufsize;              /* Allocated buffer size. */
            long    b_bcount;               /* Valid bytes in buffer. */
            long    b_resid;                /* Remaining I/O. */
            dev_t   b_dev;                  /* Device associated with buffer. */
            caddr_t b_data;                 /* Memory, superblocks, indirect etc. */
            caddr_t b_kvabase;              /* base kva for buffer */
            int     b_kvasize;              /* size of kva for buffer */
           daddr_t b_lblkno;               /* Logical block number. */
           daddr_t b_blkno;                /* Underlying physical block number. */
           off_t   b_offset;               /* Offset into file */
                                           /* Function to call upon completion. */
           void    (*b_iodone) __P((struct buf *));
                                           /* For nested b_iodone's. */
           struct  iodone_chain *b_iodone_chain;
           struct  vnode *b_vp;            /* Device vnode. */
           int     b_dirtyoff;             /* Offset in buffer of dirty region. */
           int     b_dirtyend;             /* Offset of end of dirty region. */
           struct  ucred *b_rcred;         /* Read credentials reference. */
           struct  ucred *b_wcred;         /* Write credentials reference. */
           int     b_validoff;             /* Offset in buffer of valid region. */
           int     b_validend;             /* Offset of end of valid region. */
           daddr_t b_pblkno;               /* physical block number */
           void    *b_saveaddr;            /* Original b_addr for physio. */
           caddr_t b_savekva;              /* saved kva for transfer while bouncing */
           void    *b_driver1;             /* for private use by the driver */
           void    *b_driver2;             /* for private use by the driver */
           void    *b_spc;
           union   cluster_info {
                   TAILQ_HEAD(cluster_list_head, buf) cluster_head;
                   TAILQ_ENTRY(buf) cluster_entry;
           } b_cluster;
           struct  vm_page *b_pages[btoc(MAXPHYS)];
           int             b_npages;
           struct  workhead b_dep;         /* List of filesystem dependencies. */
   };
   
   /*
    * These flags are kept in b_flags.
    */
   #define B_AGE           0x00000001      /* Move to age queue when I/O done. */
   #define B_NEEDCOMMIT    0x00000002      /* Append-write in progress. */
   #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_CACHE         0x00000020      /* Bread found us in the cache. */
   #define B_CALL          0x00000040      /* Call b_iodone from biodone. */
   #define B_DELWRI        0x00000080      /* Delay I/O until buffer reused. */
   #define B_FREEBUF       0x00000100      /* Instruct driver: free blocks */
   #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_SCANNED       0x00001000      /* VOP_FSYNC funcs mark written bufs */
   #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_MALLOC        0x00010000      /* malloced b_data */
   #define B_CLUSTEROK     0x00020000      /* Pagein op, so swap() can count it. */
   #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_DIRTY         0x00200000      /* Needs writing later. */
   #define B_RELBUF        0x00400000      /* Release VMIO buffer. */
   #define B_WANTED        0x00800000      /* Process wants this buffer. */
   #define B_WRITE         0x00000000      /* Write buffer (pseudo flag). */
   #define B_WRITEINPROG   0x01000000      /* Write in progress. */
   #define B_XXX           0x02000000      /* Debugging flag. */
   #define B_PAGING        0x04000000      /* volatile paging I/O -- bypass VMIO */
   #define B_ORDERED       0x08000000      /* Must guarantee I/O ordering */
   #define B_RAM           0x10000000      /* Read ahead mark (flag) */
   #define B_VMIO          0x20000000      /* VMIO flag */
   #define B_CLUSTER       0x40000000      /* pagein op, so swap() can count it */
   #define B_AVAIL1        0x80000000      /* Available flag */
   
   #define PRINT_BUF_FLAGS "\2\40avail1\37cluster\36vmio\35ram\34ordered" \
           "\33paging\32xxx\31writeinprog\30wanted\27relbuf\26dirty" \
           "\25read\24raw\23phys\22clusterok\21malloc\20nocache" \
           "\17locked\16inval\15avail2\14error\13eintr\12done\11freebuf" \
           "\10delwri\7call\6cache\5busy\4bad\3async\2needcommit\1age"
   
   /*
    * These flags are kept in b_xflags.
    */
   #define B_VNDIRTY       0x01            /* On vnode dirty list */
   #define B_VNCLEAN       0x02            /* On vnode clean list */
   
   #define NOOFFSET        (-1LL)          /* No buffer offset calculated yet */
   
   struct buf_queue_head {
           TAILQ_HEAD(buf_queue, buf) queue;
           daddr_t last_pblkno;
           struct  buf *insert_point;
           struct  buf *switch_point;
   };
   
   /*
    * 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. */
   };
   
   static __inline void bufq_init __P((struct buf_queue_head *head));
   
   static __inline void bufq_insert_tail __P((struct buf_queue_head *head,
                                              struct buf *bp));
   
   static __inline void bufq_remove __P((struct buf_queue_head *head,
                                         struct buf *bp));
   
   static __inline struct buf *bufq_first __P((struct buf_queue_head *head));
   
   static __inline void
   bufq_init(struct buf_queue_head *head)
   {
           TAILQ_INIT(&head->queue);
           head->last_pblkno = 0;
           head->insert_point = NULL;
           head->switch_point = NULL;
   }
   
   static __inline void
   bufq_insert_tail(struct buf_queue_head *head, struct buf *bp)
   {
           if ((bp->b_flags & B_ORDERED) != 0) {
                   head->insert_point = bp;
                   head->switch_point = NULL;
           }
           TAILQ_INSERT_TAIL(&head->queue, bp, b_act);
   }
   
   static __inline void
   bufq_remove(struct buf_queue_head *head, struct buf *bp)
   {
           if (bp == head->switch_point)
                   head->switch_point = TAILQ_NEXT(bp, b_act);
           if (bp == head->insert_point) {
                   head->insert_point = TAILQ_PREV(bp, buf_queue, b_act);
                   if (head->insert_point == NULL)
                           head->last_pblkno = 0;
           } else if (bp == TAILQ_FIRST(&head->queue))
                   head->last_pblkno = bp->b_pblkno;
           TAILQ_REMOVE(&head->queue, bp, b_act);
           if (TAILQ_FIRST(&head->queue) == head->switch_point)
                   head->switch_point = NULL;
   }
   
   static __inline struct buf *
   bufq_first(struct buf_queue_head *head)
   {
           return (TAILQ_FIRST(&head->queue));
   }
   
   
   /*
    * number of buffer hash entries
    */
   #define BUFHSZ 512
   
   /*
    * buffer hash table calculation, originally by David Greenman
    */
   #define BUFHASH(vnp, bn)        \
           (&bufhashtbl[(((uintptr_t)(vnp) >> 7)+(int)(bn)) % BUFHSZ])
   
   /*
    * Definitions for the buffer free lists.
    */
   #define BUFFER_QUEUES   6       /* number of free buffer queues */
   
   #define QUEUE_NONE      0       /* on no queue */
   #define QUEUE_LOCKED    1       /* locked buffers */
   #define QUEUE_LRU       2       /* useful buffers */
   #define QUEUE_VMIO      3       /* VMIO buffers */
   #define QUEUE_AGE       4       /* not-useful buffers */
   #define QUEUE_EMPTY     5       /* empty buffer headers*/
   
   /*
    * Zero out the buffer's data area.
    */
   #define clrbuf(bp) {                                                    \
           bzero((bp)->b_data, (u_int)(bp)->b_bcount);                     \
           (bp)->b_resid = 0;                                              \
   }
   
   /* Flags to low-level allocation routines. */
   #define B_CLRBUF        0x01    /* Request allocated buffer be cleared. */
   #define B_SYNC          0x02    /* Do all allocations synchronously. */
   
   #ifdef KERNEL
   extern int      nbuf;                   /* The number of buffer headers */
   extern struct   buf *buf;               /* The buffer headers. */
   extern char     *buffers;               /* The buffer contents. */
   extern int      bufpages;               /* Number of memory pages in the buffer pool. */
   extern struct   buf *swbuf;             /* Swap I/O buffer headers. */
   extern int      nswbuf;                 /* Number of swap I/O buffer headers. */
   extern int      needsbuffer, numdirtybuffers;
   extern TAILQ_HEAD(swqueue, buf) bswlist;
   extern TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES];
   
   struct uio;
   
   void    bufinit __P((void));
   void    bremfree __P((struct buf *));
   int     bread __P((struct vnode *, daddr_t, int,
               struct ucred *, struct buf **));
   int     breadn __P((struct vnode *, daddr_t, int, daddr_t *, int *, int,
               struct ucred *, struct buf **));
   int     bwrite __P((struct buf *));
   void    bdwrite __P((struct buf *));
   void    bawrite __P((struct buf *));
   void    bdirty __P((struct buf *));
   int     bowrite __P((struct buf *));
   void    brelse __P((struct buf *));
   void    bqrelse __P((struct buf *));
   int     vfs_bio_awrite __P((struct buf *));
   struct buf *     getpbuf __P((void));
   struct buf *incore __P((struct vnode *, daddr_t));
   struct buf *gbincore __P((struct vnode *, daddr_t));
   int     inmem __P((struct vnode *, daddr_t));
   struct buf *getblk __P((struct vnode *, daddr_t, int, int, int));
   struct buf *geteblk __P((int));
   int     allocbuf __P((struct buf *, int));
   int     biowait __P((struct buf *));
   void    biodone __P((struct buf *));
   
   void    cluster_callback __P((struct buf *));
   int     cluster_read __P((struct vnode *, u_quad_t, daddr_t, long,
               struct ucred *, long, int, struct buf **));
   int     cluster_wbuild __P((struct vnode *, long, daddr_t, int));
   void    cluster_write __P((struct buf *, u_quad_t));
   int     physio __P((void (*)(struct buf *), struct buf *, dev_t, 
               int, u_int (*)(struct buf *), struct uio *));
   u_int   minphys __P((struct buf *));
   void    vfs_bio_clrbuf __P((struct buf *));
   void    vfs_busy_pages __P((struct buf *, int clear_modify));
   void    vfs_unbusy_pages __P((struct buf *));
   void    vwakeup __P((struct buf *));
   void    vmapbuf __P((struct buf *));
   void    vunmapbuf __P((struct buf *));
   void    relpbuf __P((struct buf *));
   void    brelvp __P((struct buf *));
   void    bgetvp __P((struct vnode *, struct buf *));
   void    pbgetvp __P((struct vnode *, struct buf *));
   void    pbrelvp __P((struct buf *));
   void    reassignbuf __P((struct buf *, struct vnode *));
   struct  buf *trypbuf __P((void));
   void    vfs_bio_need_satisfy __P((void));
   #endif /* KERNEL */
   
   #endif /* !_SYS_BUF_H_ */

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