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 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 1982, 1986, 1989, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  * (c) UNIX System Laboratories, Inc.
    7  * All or some portions of this file are derived from material licensed
    8  * to the University of California by American Telephone and Telegraph
    9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   10  * the permission of UNIX System Laboratories, Inc.
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  * 1. Redistributions of source code must retain the above copyright
   16  *    notice, this list of conditions and the following disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  * 3. Neither the name of the University nor the names of its contributors
   21  *    may be used to endorse or promote products derived from this software
   22  *    without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  *      @(#)buf.h       8.9 (Berkeley) 3/30/95
   37  * $FreeBSD: stable/12/sys/sys/buf.h 333576 2018-05-13 09:47:28Z kib $
   38  */
   39 
   40 #ifndef _SYS_BUF_H_
   41 #define _SYS_BUF_H_
   42 
   43 #include <sys/bufobj.h>
   44 #include <sys/queue.h>
   45 #include <sys/lock.h>
   46 #include <sys/lockmgr.h>
   47 
   48 struct bio;
   49 struct buf;
   50 struct bufobj;
   51 struct mount;
   52 struct vnode;
   53 struct uio;
   54 
   55 /*
   56  * To avoid including <ufs/ffs/softdep.h> 
   57  */   
   58 LIST_HEAD(workhead, worklist);
   59 /*
   60  * These are currently used only by the soft dependency code, hence
   61  * are stored once in a global variable. If other subsystems wanted
   62  * to use these hooks, a pointer to a set of bio_ops could be added
   63  * to each buffer.
   64  */
   65 extern struct bio_ops {
   66         void    (*io_start)(struct buf *);
   67         void    (*io_complete)(struct buf *);
   68         void    (*io_deallocate)(struct buf *);
   69         int     (*io_countdeps)(struct buf *, int);
   70 } bioops;
   71 
   72 struct vm_object;
   73 struct vm_page;
   74 
   75 typedef uint32_t b_xflags_t;
   76 
   77 /*
   78  * The buffer header describes an I/O operation in the kernel.
   79  *
   80  * NOTES:
   81  *      b_bufsize, b_bcount.  b_bufsize is the allocation size of the
   82  *      buffer, either DEV_BSIZE or PAGE_SIZE aligned.  b_bcount is the
   83  *      originally requested buffer size and can serve as a bounds check
   84  *      against EOF.  For most, but not all uses, b_bcount == b_bufsize.
   85  *
   86  *      b_dirtyoff, b_dirtyend.  Buffers support piecemeal, unaligned
   87  *      ranges of dirty data that need to be written to backing store.
   88  *      The range is typically clipped at b_bcount ( not b_bufsize ).
   89  *
   90  *      b_resid.  Number of bytes remaining in I/O.  After an I/O operation
   91  *      completes, b_resid is usually 0 indicating 100% success.
   92  *
   93  *      All fields are protected by the buffer lock except those marked:
   94  *              V - Protected by owning bufobj lock
   95  *              Q - Protected by the buf queue lock
   96  *              D - Protected by an dependency implementation specific lock
   97  */
   98 struct buf {
   99         struct bufobj   *b_bufobj;
  100         long            b_bcount;
  101         void            *b_caller1;
  102         caddr_t         b_data;
  103         int             b_error;
  104         uint16_t        b_iocmd;        /* BIO_* bio_cmd from bio.h */
  105         uint16_t        b_ioflags;      /* BIO_* bio_flags from bio.h */
  106         off_t           b_iooffset;
  107         long            b_resid;
  108         void    (*b_iodone)(struct buf *);
  109         void    (*b_ckhashcalc)(struct buf *);
  110         uint64_t        b_ckhash;       /* B_CKHASH requested check-hash */
  111         daddr_t b_blkno;                /* Underlying physical block number. */
  112         off_t   b_offset;               /* Offset into file. */
  113         TAILQ_ENTRY(buf) b_bobufs;      /* (V) Buffer's associated vnode. */
  114         uint32_t        b_vflags;       /* (V) BV_* flags */
  115         uint8_t         b_qindex;       /* (Q) buffer queue index */
  116         uint8_t         b_domain;       /* (Q) buf domain this resides in */
  117         uint16_t        b_subqueue;     /* (Q) per-cpu q if any */
  118         uint32_t        b_flags;        /* B_* flags. */
  119         b_xflags_t b_xflags;            /* extra flags */
  120         struct lock b_lock;             /* Buffer lock */
  121         long    b_bufsize;              /* Allocated buffer size. */
  122         int     b_runningbufspace;      /* when I/O is running, pipelining */
  123         int     b_kvasize;              /* size of kva for buffer */
  124         int     b_dirtyoff;             /* Offset in buffer of dirty region. */
  125         int     b_dirtyend;             /* Offset of end of dirty region. */
  126         caddr_t b_kvabase;              /* base kva for buffer */
  127         daddr_t b_lblkno;               /* Logical block number. */
  128         struct  vnode *b_vp;            /* Device vnode. */
  129         struct  ucred *b_rcred;         /* Read credentials reference. */
  130         struct  ucred *b_wcred;         /* Write credentials reference. */
  131         union {
  132                 TAILQ_ENTRY(buf) b_freelist; /* (Q) */
  133                 struct {
  134                         void    (*b_pgiodone)(void *, vm_page_t *, int, int);
  135                         int     b_pgbefore;
  136                         int     b_pgafter;
  137                 };
  138         };
  139         union   cluster_info {
  140                 TAILQ_HEAD(cluster_list_head, buf) cluster_head;
  141                 TAILQ_ENTRY(buf) cluster_entry;
  142         } b_cluster;
  143         struct  vm_page *b_pages[btoc(MAXPHYS)];
  144         int             b_npages;
  145         struct  workhead b_dep;         /* (D) List of filesystem dependencies. */
  146         void    *b_fsprivate1;
  147         void    *b_fsprivate2;
  148         void    *b_fsprivate3;
  149 
  150 #if defined(FULL_BUF_TRACKING)
  151 #define BUF_TRACKING_SIZE       32
  152 #define BUF_TRACKING_ENTRY(x)   ((x) & (BUF_TRACKING_SIZE - 1))
  153         const char      *b_io_tracking[BUF_TRACKING_SIZE];
  154         uint32_t        b_io_tcnt;
  155 #elif defined(BUF_TRACKING)
  156         const char      *b_io_tracking;
  157 #endif
  158 };
  159 
  160 #define b_object        b_bufobj->bo_object
  161 
  162 /*
  163  * These flags are kept in b_flags.
  164  *
  165  * Notes:
  166  *
  167  *      B_ASYNC         VOP calls on bp's are usually async whether or not
  168  *                      B_ASYNC is set, but some subsystems, such as NFS, like 
  169  *                      to know what is best for the caller so they can
  170  *                      optimize the I/O.
  171  *
  172  *      B_PAGING        Indicates that bp is being used by the paging system or
  173  *                      some paging system and that the bp is not linked into
  174  *                      the b_vp's clean/dirty linked lists or ref counts.
  175  *                      Buffer vp reassignments are illegal in this case.
  176  *
  177  *      B_CACHE         This may only be set if the buffer is entirely valid.
  178  *                      The situation where B_DELWRI is set and B_CACHE is
  179  *                      clear MUST be committed to disk by getblk() so 
  180  *                      B_DELWRI can also be cleared.  See the comments for
  181  *                      getblk() in kern/vfs_bio.c.  If B_CACHE is clear,
  182  *                      the caller is expected to clear BIO_ERROR and B_INVAL,
  183  *                      set BIO_READ, and initiate an I/O.
  184  *
  185  *                      The 'entire buffer' is defined to be the range from
  186  *                      0 through b_bcount.
  187  *
  188  *      B_MALLOC        Request that the buffer be allocated from the malloc
  189  *                      pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
  190  *
  191  *      B_CLUSTEROK     This flag is typically set for B_DELWRI buffers
  192  *                      by filesystems that allow clustering when the buffer
  193  *                      is fully dirty and indicates that it may be clustered
  194  *                      with other adjacent dirty buffers.  Note the clustering
  195  *                      may not be used with the stage 1 data write under NFS
  196  *                      but may be used for the commit rpc portion.
  197  *
  198  *      B_VMIO          Indicates that the buffer is tied into an VM object.
  199  *                      The buffer's data is always PAGE_SIZE aligned even
  200  *                      if b_bufsize and b_bcount are not.  ( b_bufsize is 
  201  *                      always at least DEV_BSIZE aligned, though ).
  202  *
  203  *      B_DIRECT        Hint that we should attempt to completely free
  204  *                      the pages underlying the buffer.  B_DIRECT is
  205  *                      sticky until the buffer is released and typically
  206  *                      only has an effect when B_RELBUF is also set.
  207  *
  208  */
  209 
  210 #define B_AGE           0x00000001      /* Move to age queue when I/O done. */
  211 #define B_NEEDCOMMIT    0x00000002      /* Append-write in progress. */
  212 #define B_ASYNC         0x00000004      /* Start I/O, do not wait. */
  213 #define B_DIRECT        0x00000008      /* direct I/O flag (pls free vmio) */
  214 #define B_DEFERRED      0x00000010      /* Skipped over for cleaning */
  215 #define B_CACHE         0x00000020      /* Bread found us in the cache. */
  216 #define B_VALIDSUSPWRT  0x00000040      /* Valid write during suspension. */
  217 #define B_DELWRI        0x00000080      /* Delay I/O until buffer reused. */
  218 #define B_CKHASH        0x00000100      /* checksum hash calculated on read */
  219 #define B_DONE          0x00000200      /* I/O completed. */
  220 #define B_EINTR         0x00000400      /* I/O was interrupted */
  221 #define B_NOREUSE       0x00000800      /* Contents not reused once released. */
  222 #define B_REUSE         0x00001000      /* Contents reused, second chance. */
  223 #define B_INVAL         0x00002000      /* Does not contain valid info. */
  224 #define B_BARRIER       0x00004000      /* Write this and all preceding first. */
  225 #define B_NOCACHE       0x00008000      /* Do not cache block after use. */
  226 #define B_MALLOC        0x00010000      /* malloced b_data */
  227 #define B_CLUSTEROK     0x00020000      /* Pagein op, so swap() can count it. */
  228 #define B_00040000      0x00040000      /* Available flag. */
  229 #define B_00080000      0x00080000      /* Available flag. */
  230 #define B_00100000      0x00100000      /* Available flag. */
  231 #define B_00200000      0x00200000      /* Available flag. */
  232 #define B_RELBUF        0x00400000      /* Release VMIO buffer. */
  233 #define B_FS_FLAG1      0x00800000      /* Available flag for FS use. */
  234 #define B_NOCOPY        0x01000000      /* Don't copy-on-write this buf. */
  235 #define B_INFREECNT     0x02000000      /* buf is counted in numfreebufs */
  236 #define B_PAGING        0x04000000      /* volatile paging I/O -- bypass VMIO */
  237 #define B_MANAGED       0x08000000      /* Managed by FS. */
  238 #define B_RAM           0x10000000      /* Read ahead mark (flag) */
  239 #define B_VMIO          0x20000000      /* VMIO flag */
  240 #define B_CLUSTER       0x40000000      /* pagein op, so swap() can count it */
  241 #define B_REMFREE       0x80000000      /* Delayed bremfree */
  242 
  243 #define PRINT_BUF_FLAGS "\2\40remfree\37cluster\36vmio\35ram\34managed" \
  244         "\33paging\32infreecnt\31nocopy\30b23\27relbuf\26b21\25b20" \
  245         "\24b19\23b18\22clusterok\21malloc\20nocache\17b14\16inval" \
  246         "\15reuse\14noreuse\13eintr\12done\11b8\10delwri" \
  247         "\7validsuspwrt\6cache\5deferred\4direct\3async\2needcommit\1age"
  248 
  249 /*
  250  * These flags are kept in b_xflags.
  251  *
  252  * BX_FSPRIV reserves a set of eight flags that may be used by individual
  253  * filesystems for their own purpose. Their specific definitions are
  254  * found in the header files for each filesystem that uses them.
  255  */
  256 #define BX_VNDIRTY      0x00000001      /* On vnode dirty list */
  257 #define BX_VNCLEAN      0x00000002      /* On vnode clean list */
  258 #define BX_BKGRDWRITE   0x00000010      /* Do writes in background */
  259 #define BX_BKGRDMARKER  0x00000020      /* Mark buffer for splay tree */
  260 #define BX_ALTDATA      0x00000040      /* Holds extended data */
  261 #define BX_FSPRIV       0x00FF0000      /* filesystem-specific flags mask */
  262 
  263 #define PRINT_BUF_XFLAGS "\2\7altdata\6bkgrdmarker\5bkgrdwrite\2clean\1dirty"
  264 
  265 #define NOOFFSET        (-1LL)          /* No buffer offset calculated yet */
  266 
  267 /*
  268  * These flags are kept in b_vflags.
  269  */
  270 #define BV_SCANNED      0x00000001      /* VOP_FSYNC funcs mark written bufs */
  271 #define BV_BKGRDINPROG  0x00000002      /* Background write in progress */
  272 #define BV_BKGRDWAIT    0x00000004      /* Background write waiting */
  273 #define BV_BKGRDERR     0x00000008      /* Error from background write */
  274 
  275 #define PRINT_BUF_VFLAGS "\2\4bkgrderr\3bkgrdwait\2bkgrdinprog\1scanned"
  276 
  277 #ifdef _KERNEL
  278 /*
  279  * Buffer locking
  280  */
  281 extern const char *buf_wmesg;           /* Default buffer lock message */
  282 #define BUF_WMESG "bufwait"
  283 #include <sys/proc.h>                   /* XXX for curthread */
  284 #include <sys/mutex.h>
  285 
  286 /*
  287  * Initialize a lock.
  288  */
  289 #define BUF_LOCKINIT(bp)                                                \
  290         lockinit(&(bp)->b_lock, PRIBIO + 4, buf_wmesg, 0, 0)
  291 /*
  292  *
  293  * Get a lock sleeping non-interruptably until it becomes available.
  294  */
  295 #define BUF_LOCK(bp, locktype, interlock)                               \
  296         _lockmgr_args_rw(&(bp)->b_lock, (locktype), (interlock),        \
  297             LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT,         \
  298             LOCK_FILE, LOCK_LINE)
  299 
  300 /*
  301  * Get a lock sleeping with specified interruptably and timeout.
  302  */
  303 #define BUF_TIMELOCK(bp, locktype, interlock, wmesg, catch, timo)       \
  304         _lockmgr_args_rw(&(bp)->b_lock, (locktype) | LK_TIMELOCK,       \
  305             (interlock), (wmesg), (PRIBIO + 4) | (catch), (timo),       \
  306             LOCK_FILE, LOCK_LINE)
  307 
  308 /*
  309  * Release a lock. Only the acquiring process may free the lock unless
  310  * it has been handed off to biodone.
  311  */
  312 #define BUF_UNLOCK(bp) do {                                             \
  313         KASSERT(((bp)->b_flags & B_REMFREE) == 0,                       \
  314             ("BUF_UNLOCK %p while B_REMFREE is still set.", (bp)));     \
  315                                                                         \
  316         (void)_lockmgr_args(&(bp)->b_lock, LK_RELEASE, NULL,            \
  317             LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT,         \
  318             LOCK_FILE, LOCK_LINE);                                      \
  319 } while (0)
  320 
  321 /*
  322  * Check if a buffer lock is recursed.
  323  */
  324 #define BUF_LOCKRECURSED(bp)                                            \
  325         lockmgr_recursed(&(bp)->b_lock)
  326 
  327 /*
  328  * Check if a buffer lock is currently held.
  329  */
  330 #define BUF_ISLOCKED(bp)                                                \
  331         lockstatus(&(bp)->b_lock)
  332 /*
  333  * Free a buffer lock.
  334  */
  335 #define BUF_LOCKFREE(bp)                                                \
  336         lockdestroy(&(bp)->b_lock)
  337 
  338 /*
  339  * Print informations on a buffer lock.
  340  */
  341 #define BUF_LOCKPRINTINFO(bp)                                           \
  342         lockmgr_printinfo(&(bp)->b_lock)
  343 
  344 /*
  345  * Buffer lock assertions.
  346  */
  347 #if defined(INVARIANTS) && defined(INVARIANT_SUPPORT)
  348 #define BUF_ASSERT_LOCKED(bp)                                           \
  349         _lockmgr_assert(&(bp)->b_lock, KA_LOCKED, LOCK_FILE, LOCK_LINE)
  350 #define BUF_ASSERT_SLOCKED(bp)                                          \
  351         _lockmgr_assert(&(bp)->b_lock, KA_SLOCKED, LOCK_FILE, LOCK_LINE)
  352 #define BUF_ASSERT_XLOCKED(bp)                                          \
  353         _lockmgr_assert(&(bp)->b_lock, KA_XLOCKED, LOCK_FILE, LOCK_LINE)
  354 #define BUF_ASSERT_UNLOCKED(bp)                                         \
  355         _lockmgr_assert(&(bp)->b_lock, KA_UNLOCKED, LOCK_FILE, LOCK_LINE)
  356 #define BUF_ASSERT_HELD(bp)
  357 #define BUF_ASSERT_UNHELD(bp)
  358 #else
  359 #define BUF_ASSERT_LOCKED(bp)
  360 #define BUF_ASSERT_SLOCKED(bp)
  361 #define BUF_ASSERT_XLOCKED(bp)
  362 #define BUF_ASSERT_UNLOCKED(bp)
  363 #define BUF_ASSERT_HELD(bp)
  364 #define BUF_ASSERT_UNHELD(bp)
  365 #endif
  366 
  367 #ifdef _SYS_PROC_H_     /* Avoid #include <sys/proc.h> pollution */
  368 /*
  369  * When initiating asynchronous I/O, change ownership of the lock to the
  370  * kernel. Once done, the lock may legally released by biodone. The
  371  * original owning process can no longer acquire it recursively, but must
  372  * wait until the I/O is completed and the lock has been freed by biodone.
  373  */
  374 #define BUF_KERNPROC(bp)                                                \
  375         _lockmgr_disown(&(bp)->b_lock, LOCK_FILE, LOCK_LINE)
  376 #endif
  377 
  378 #endif /* _KERNEL */
  379 
  380 struct buf_queue_head {
  381         TAILQ_HEAD(buf_queue, buf) queue;
  382         daddr_t last_pblkno;
  383         struct  buf *insert_point;
  384         struct  buf *switch_point;
  385 };
  386 
  387 /*
  388  * This structure describes a clustered I/O. 
  389  */
  390 struct cluster_save {
  391         long    bs_bcount;              /* Saved b_bcount. */
  392         long    bs_bufsize;             /* Saved b_bufsize. */
  393         int     bs_nchildren;           /* Number of associated buffers. */
  394         struct buf **bs_children;       /* List of associated buffers. */
  395 };
  396 
  397 #ifdef _KERNEL
  398 
  399 static __inline int
  400 bwrite(struct buf *bp)
  401 {
  402 
  403         KASSERT(bp->b_bufobj != NULL, ("bwrite: no bufobj bp=%p", bp));
  404         KASSERT(bp->b_bufobj->bo_ops != NULL, ("bwrite: no bo_ops bp=%p", bp));
  405         KASSERT(bp->b_bufobj->bo_ops->bop_write != NULL,
  406             ("bwrite: no bop_write bp=%p", bp));
  407         return (BO_WRITE(bp->b_bufobj, bp));
  408 }
  409 
  410 static __inline void
  411 bstrategy(struct buf *bp)
  412 {
  413 
  414         KASSERT(bp->b_bufobj != NULL, ("bstrategy: no bufobj bp=%p", bp));
  415         KASSERT(bp->b_bufobj->bo_ops != NULL,
  416             ("bstrategy: no bo_ops bp=%p", bp));
  417         KASSERT(bp->b_bufobj->bo_ops->bop_strategy != NULL,
  418             ("bstrategy: no bop_strategy bp=%p", bp));
  419         BO_STRATEGY(bp->b_bufobj, bp);
  420 }
  421 
  422 static __inline void
  423 buf_start(struct buf *bp)
  424 {
  425         if (bioops.io_start)
  426                 (*bioops.io_start)(bp);
  427 }
  428 
  429 static __inline void
  430 buf_complete(struct buf *bp)
  431 {
  432         if (bioops.io_complete)
  433                 (*bioops.io_complete)(bp);
  434 }
  435 
  436 static __inline void
  437 buf_deallocate(struct buf *bp)
  438 {
  439         if (bioops.io_deallocate)
  440                 (*bioops.io_deallocate)(bp);
  441 }
  442 
  443 static __inline int
  444 buf_countdeps(struct buf *bp, int i)
  445 {
  446         if (bioops.io_countdeps)
  447                 return ((*bioops.io_countdeps)(bp, i));
  448         else
  449                 return (0);
  450 }
  451 
  452 static __inline void
  453 buf_track(struct buf *bp, const char *location)
  454 {
  455 
  456 #if defined(FULL_BUF_TRACKING)
  457         bp->b_io_tracking[BUF_TRACKING_ENTRY(bp->b_io_tcnt++)] = location;
  458 #elif defined(BUF_TRACKING)
  459         bp->b_io_tracking = location;
  460 #endif
  461 }
  462 
  463 #endif /* _KERNEL */
  464 
  465 /*
  466  * Zero out the buffer's data area.
  467  */
  468 #define clrbuf(bp) {                                                    \
  469         bzero((bp)->b_data, (u_int)(bp)->b_bcount);                     \
  470         (bp)->b_resid = 0;                                              \
  471 }
  472 
  473 /*
  474  * Flags for getblk's last parameter.
  475  */
  476 #define GB_LOCK_NOWAIT  0x0001          /* Fail if we block on a buf lock. */
  477 #define GB_NOCREAT      0x0002          /* Don't create a buf if not found. */
  478 #define GB_NOWAIT_BD    0x0004          /* Do not wait for bufdaemon. */
  479 #define GB_UNMAPPED     0x0008          /* Do not mmap buffer pages. */
  480 #define GB_KVAALLOC     0x0010          /* But allocate KVA. */
  481 #define GB_CKHASH       0x0020          /* If reading, calc checksum hash */
  482 #define GB_NOSPARSE     0x0040          /* Do not instantiate holes */
  483 
  484 #ifdef _KERNEL
  485 extern int      nbuf;                   /* The number of buffer headers */
  486 extern long     maxswzone;              /* Max KVA for swap structures */
  487 extern long     maxbcache;              /* Max KVA for buffer cache */
  488 extern int      maxbcachebuf;           /* Max buffer cache block size */
  489 extern long     runningbufspace;
  490 extern long     hibufspace;
  491 extern int      dirtybufthresh;
  492 extern int      bdwriteskip;
  493 extern int      dirtybufferflushes;
  494 extern int      altbufferflushes;
  495 extern int      nswbuf;                 /* Number of swap I/O buffer headers. */
  496 extern int      cluster_pbuf_freecnt;   /* Number of pbufs for clusters */
  497 extern int      vnode_pbuf_freecnt;     /* Number of pbufs for vnode pager */
  498 extern int      vnode_async_pbuf_freecnt; /* Number of pbufs for vnode pager,
  499                                              asynchronous reads */
  500 extern caddr_t  unmapped_buf;   /* Data address for unmapped buffers. */
  501 
  502 static inline int
  503 buf_mapped(struct buf *bp)
  504 {
  505 
  506         return (bp->b_data != unmapped_buf);
  507 }
  508 
  509 void    runningbufwakeup(struct buf *);
  510 void    waitrunningbufspace(void);
  511 caddr_t kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est);
  512 void    bufinit(void);
  513 void    bufshutdown(int);
  514 void    bdata2bio(struct buf *bp, struct bio *bip);
  515 void    bwillwrite(void);
  516 int     buf_dirty_count_severe(void);
  517 void    bremfree(struct buf *);
  518 void    bremfreef(struct buf *);        /* XXX Force bremfree, only for nfs. */
  519 #define bread(vp, blkno, size, cred, bpp) \
  520             breadn_flags(vp, blkno, size, NULL, NULL, 0, cred, 0, NULL, bpp)
  521 #define bread_gb(vp, blkno, size, cred, gbflags, bpp) \
  522             breadn_flags(vp, blkno, size, NULL, NULL, 0, cred, \
  523                 gbflags, NULL, bpp)
  524 #define breadn(vp, blkno, size, rablkno, rabsize, cnt, cred, bpp) \
  525             breadn_flags(vp, blkno, size, rablkno, rabsize, cnt, cred, \
  526                 0, NULL, bpp)
  527 int     breadn_flags(struct vnode *, daddr_t, int, daddr_t *, int *, int,
  528             struct ucred *, int, void (*)(struct buf *), struct buf **);
  529 void    bdwrite(struct buf *);
  530 void    bawrite(struct buf *);
  531 void    babarrierwrite(struct buf *);
  532 int     bbarrierwrite(struct buf *);
  533 void    bdirty(struct buf *);
  534 void    bundirty(struct buf *);
  535 void    bufstrategy(struct bufobj *, struct buf *);
  536 void    brelse(struct buf *);
  537 void    bqrelse(struct buf *);
  538 int     vfs_bio_awrite(struct buf *);
  539 void    vfs_drain_busy_pages(struct buf *bp);
  540 struct buf *     getpbuf(int *);
  541 struct buf *incore(struct bufobj *, daddr_t);
  542 struct buf *gbincore(struct bufobj *, daddr_t);
  543 struct buf *getblk(struct vnode *, daddr_t, int, int, int, int);
  544 int     getblkx(struct vnode *vp, daddr_t blkno, int size, int slpflag,
  545             int slptimeo, int flags, struct buf **bpp);
  546 struct buf *geteblk(int, int);
  547 int     bufwait(struct buf *);
  548 int     bufwrite(struct buf *);
  549 void    bufdone(struct buf *);
  550 void    bd_speedup(void);
  551 
  552 int     cluster_read(struct vnode *, u_quad_t, daddr_t, long,
  553             struct ucred *, long, int, int, struct buf **);
  554 int     cluster_wbuild(struct vnode *, long, daddr_t, int, int);
  555 void    cluster_write(struct vnode *, struct buf *, u_quad_t, int, int);
  556 void    vfs_bio_brelse(struct buf *bp, int ioflags);
  557 void    vfs_bio_bzero_buf(struct buf *bp, int base, int size);
  558 void    vfs_bio_clrbuf(struct buf *);
  559 void    vfs_bio_set_flags(struct buf *bp, int ioflags);
  560 void    vfs_bio_set_valid(struct buf *, int base, int size);
  561 void    vfs_busy_pages(struct buf *, int clear_modify);
  562 void    vfs_unbusy_pages(struct buf *);
  563 int     vmapbuf(struct buf *, int);
  564 void    vunmapbuf(struct buf *);
  565 void    relpbuf(struct buf *, int *);
  566 void    brelvp(struct buf *);
  567 void    bgetvp(struct vnode *, struct buf *);
  568 void    pbgetbo(struct bufobj *bo, struct buf *bp);
  569 void    pbgetvp(struct vnode *, struct buf *);
  570 void    pbrelbo(struct buf *);
  571 void    pbrelvp(struct buf *);
  572 int     allocbuf(struct buf *bp, int size);
  573 void    reassignbuf(struct buf *);
  574 struct  buf *trypbuf(int *);
  575 void    bwait(struct buf *, u_char, const char *);
  576 void    bdone(struct buf *);
  577 
  578 typedef daddr_t (vbg_get_lblkno_t)(struct vnode *, vm_ooffset_t);
  579 typedef int (vbg_get_blksize_t)(struct vnode *, daddr_t);
  580 int     vfs_bio_getpages(struct vnode *vp, struct vm_page **ma, int count,
  581             int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
  582             vbg_get_blksize_t get_blksize);
  583 
  584 #endif /* _KERNEL */
  585 
  586 #endif /* !_SYS_BUF_H_ */

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