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  * Copyright (c) 1982, 1986, 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)buf.h       8.9 (Berkeley) 3/30/95
   35  * $FreeBSD: releng/11.2/sys/sys/buf.h 331722 2018-03-29 02:50:57Z eadler $
   36  */
   37 
   38 #ifndef _SYS_BUF_H_
   39 #define _SYS_BUF_H_
   40 
   41 #include <sys/bufobj.h>
   42 #include <sys/queue.h>
   43 #include <sys/lock.h>
   44 #include <sys/lockmgr.h>
   45 
   46 struct bio;
   47 struct buf;
   48 struct bufobj;
   49 struct mount;
   50 struct vnode;
   51 struct uio;
   52 
   53 /*
   54  * To avoid including <ufs/ffs/softdep.h> 
   55  */   
   56 LIST_HEAD(workhead, worklist);
   57 /*
   58  * These are currently used only by the soft dependency code, hence
   59  * are stored once in a global variable. If other subsystems wanted
   60  * to use these hooks, a pointer to a set of bio_ops could be added
   61  * to each buffer.
   62  */
   63 extern struct bio_ops {
   64         void    (*io_start)(struct buf *);
   65         void    (*io_complete)(struct buf *);
   66         void    (*io_deallocate)(struct buf *);
   67         int     (*io_countdeps)(struct buf *, int);
   68 } bioops;
   69 
   70 struct vm_object;
   71 struct vm_page;
   72 
   73 typedef unsigned char b_xflags_t;
   74 
   75 /*
   76  * The buffer header describes an I/O operation in the kernel.
   77  *
   78  * NOTES:
   79  *      b_bufsize, b_bcount.  b_bufsize is the allocation size of the
   80  *      buffer, either DEV_BSIZE or PAGE_SIZE aligned.  b_bcount is the
   81  *      originally requested buffer size and can serve as a bounds check
   82  *      against EOF.  For most, but not all uses, b_bcount == b_bufsize.
   83  *
   84  *      b_dirtyoff, b_dirtyend.  Buffers support piecemeal, unaligned
   85  *      ranges of dirty data that need to be written to backing store.
   86  *      The range is typically clipped at b_bcount ( not b_bufsize ).
   87  *
   88  *      b_resid.  Number of bytes remaining in I/O.  After an I/O operation
   89  *      completes, b_resid is usually 0 indicating 100% success.
   90  *
   91  *      All fields are protected by the buffer lock except those marked:
   92  *              V - Protected by owning bufobj lock
   93  *              Q - Protected by the buf queue lock
   94  *              D - Protected by an dependency implementation specific lock
   95  */
   96 struct buf {
   97         struct bufobj   *b_bufobj;
   98         long            b_bcount;
   99         void            *b_caller1;
  100         caddr_t         b_data;
  101         int             b_error;
  102         uint16_t        b_iocmd;        /* BIO_* bio_cmd from bio.h */
  103         uint16_t        b_ioflags;      /* BIO_* bio_flags from bio.h */
  104         off_t           b_iooffset;
  105         long            b_resid;
  106         void    (*b_iodone)(struct buf *);
  107         daddr_t b_blkno;                /* Underlying physical block number. */
  108         off_t   b_offset;               /* Offset into file. */
  109         TAILQ_ENTRY(buf) b_bobufs;      /* (V) Buffer's associated vnode. */
  110         uint32_t        b_vflags;       /* (V) BV_* flags */
  111         unsigned short b_qindex;        /* (Q) buffer queue index */
  112         uint32_t        b_flags;        /* B_* flags. */
  113         b_xflags_t b_xflags;            /* extra flags */
  114         struct lock b_lock;             /* Buffer lock */
  115         long    b_bufsize;              /* Allocated buffer size. */
  116         int     b_runningbufspace;      /* when I/O is running, pipelining */
  117         int     b_kvasize;              /* size of kva for buffer */
  118         int     b_dirtyoff;             /* Offset in buffer of dirty region. */
  119         int     b_dirtyend;             /* Offset of end of dirty region. */
  120         caddr_t b_kvabase;              /* base kva for buffer */
  121         daddr_t b_lblkno;               /* Logical block number. */
  122         struct  vnode *b_vp;            /* Device vnode. */
  123         struct  ucred *b_rcred;         /* Read credentials reference. */
  124         struct  ucred *b_wcred;         /* Write credentials reference. */
  125         union {
  126                 TAILQ_ENTRY(buf) b_freelist; /* (Q) */
  127                 struct {
  128                         void    (*b_pgiodone)(void *, vm_page_t *, int, int);
  129                         int     b_pgbefore;
  130                         int     b_pgafter;
  131                 };
  132         };
  133         union   cluster_info {
  134                 TAILQ_HEAD(cluster_list_head, buf) cluster_head;
  135                 TAILQ_ENTRY(buf) cluster_entry;
  136         } b_cluster;
  137         struct  vm_page *b_pages[btoc(MAXPHYS)];
  138         int             b_npages;
  139         struct  workhead b_dep;         /* (D) List of filesystem dependencies. */
  140         void    *b_fsprivate1;
  141         void    *b_fsprivate2;
  142         void    *b_fsprivate3;
  143         int     b_pin_count;
  144 };
  145 
  146 #define b_object        b_bufobj->bo_object
  147 
  148 /*
  149  * These flags are kept in b_flags.
  150  *
  151  * Notes:
  152  *
  153  *      B_ASYNC         VOP calls on bp's are usually async whether or not
  154  *                      B_ASYNC is set, but some subsystems, such as NFS, like 
  155  *                      to know what is best for the caller so they can
  156  *                      optimize the I/O.
  157  *
  158  *      B_PAGING        Indicates that bp is being used by the paging system or
  159  *                      some paging system and that the bp is not linked into
  160  *                      the b_vp's clean/dirty linked lists or ref counts.
  161  *                      Buffer vp reassignments are illegal in this case.
  162  *
  163  *      B_CACHE         This may only be set if the buffer is entirely valid.
  164  *                      The situation where B_DELWRI is set and B_CACHE is
  165  *                      clear MUST be committed to disk by getblk() so 
  166  *                      B_DELWRI can also be cleared.  See the comments for
  167  *                      getblk() in kern/vfs_bio.c.  If B_CACHE is clear,
  168  *                      the caller is expected to clear BIO_ERROR and B_INVAL,
  169  *                      set BIO_READ, and initiate an I/O.
  170  *
  171  *                      The 'entire buffer' is defined to be the range from
  172  *                      0 through b_bcount.
  173  *
  174  *      B_MALLOC        Request that the buffer be allocated from the malloc
  175  *                      pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
  176  *
  177  *      B_CLUSTEROK     This flag is typically set for B_DELWRI buffers
  178  *                      by filesystems that allow clustering when the buffer
  179  *                      is fully dirty and indicates that it may be clustered
  180  *                      with other adjacent dirty buffers.  Note the clustering
  181  *                      may not be used with the stage 1 data write under NFS
  182  *                      but may be used for the commit rpc portion.
  183  *
  184  *      B_VMIO          Indicates that the buffer is tied into an VM object.
  185  *                      The buffer's data is always PAGE_SIZE aligned even
  186  *                      if b_bufsize and b_bcount are not.  ( b_bufsize is 
  187  *                      always at least DEV_BSIZE aligned, though ).
  188  *
  189  *      B_DIRECT        Hint that we should attempt to completely free
  190  *                      the pages underlying the buffer.  B_DIRECT is
  191  *                      sticky until the buffer is released and typically
  192  *                      only has an effect when B_RELBUF is also set.
  193  *
  194  */
  195 
  196 #define B_AGE           0x00000001      /* Move to age queue when I/O done. */
  197 #define B_NEEDCOMMIT    0x00000002      /* Append-write in progress. */
  198 #define B_ASYNC         0x00000004      /* Start I/O, do not wait. */
  199 #define B_DIRECT        0x00000008      /* direct I/O flag (pls free vmio) */
  200 #define B_DEFERRED      0x00000010      /* Skipped over for cleaning */
  201 #define B_CACHE         0x00000020      /* Bread found us in the cache. */
  202 #define B_VALIDSUSPWRT  0x00000040      /* Valid write during suspension. */
  203 #define B_DELWRI        0x00000080      /* Delay I/O until buffer reused. */
  204 #define B_00000100      0x00000100      /* Available flag. */
  205 #define B_DONE          0x00000200      /* I/O completed. */
  206 #define B_EINTR         0x00000400      /* I/O was interrupted */
  207 #define B_NOREUSE       0x00000800      /* Contents not reused once released. */
  208 #define B_00001000      0x00001000      /* Available flag. */
  209 #define B_INVAL         0x00002000      /* Does not contain valid info. */
  210 #define B_BARRIER       0x00004000      /* Write this and all preceding first. */
  211 #define B_NOCACHE       0x00008000      /* Do not cache block after use. */
  212 #define B_MALLOC        0x00010000      /* malloced b_data */
  213 #define B_CLUSTEROK     0x00020000      /* Pagein op, so swap() can count it. */
  214 #define B_00040000      0x00040000      /* Available flag. */
  215 #define B_00080000      0x00080000      /* Available flag. */
  216 #define B_00100000      0x00100000      /* Available flag. */
  217 #define B_00200000      0x00200000      /* Available flag. */
  218 #define B_RELBUF        0x00400000      /* Release VMIO buffer. */
  219 #define B_FS_FLAG1      0x00800000      /* Available flag for FS use. */
  220 #define B_NOCOPY        0x01000000      /* Don't copy-on-write this buf. */
  221 #define B_INFREECNT     0x02000000      /* buf is counted in numfreebufs */
  222 #define B_PAGING        0x04000000      /* volatile paging I/O -- bypass VMIO */
  223 #define B_MANAGED       0x08000000      /* Managed by FS. */
  224 #define B_RAM           0x10000000      /* Read ahead mark (flag) */
  225 #define B_VMIO          0x20000000      /* VMIO flag */
  226 #define B_CLUSTER       0x40000000      /* pagein op, so swap() can count it */
  227 #define B_REMFREE       0x80000000      /* Delayed bremfree */
  228 
  229 #define PRINT_BUF_FLAGS "\2\40remfree\37cluster\36vmio\35ram\34managed" \
  230         "\33paging\32infreecnt\31nocopy\30b23\27relbuf\26b21\25b20" \
  231         "\24b19\23b18\22clusterok\21malloc\20nocache\17b14\16inval" \
  232         "\15b12\14noreuse\13eintr\12done\11b8\10delwri" \
  233         "\7validsuspwrt\6cache\5deferred\4direct\3async\2needcommit\1age"
  234 
  235 /*
  236  * These flags are kept in b_xflags.
  237  */
  238 #define BX_VNDIRTY      0x00000001      /* On vnode dirty list */
  239 #define BX_VNCLEAN      0x00000002      /* On vnode clean list */
  240 #define BX_BKGRDWRITE   0x00000010      /* Do writes in background */
  241 #define BX_BKGRDMARKER  0x00000020      /* Mark buffer for splay tree */
  242 #define BX_ALTDATA      0x00000040      /* Holds extended data */
  243 
  244 #define PRINT_BUF_XFLAGS "\2\7altdata\6bkgrdmarker\5bkgrdwrite\2clean\1dirty"
  245 
  246 #define NOOFFSET        (-1LL)          /* No buffer offset calculated yet */
  247 
  248 /*
  249  * These flags are kept in b_vflags.
  250  */
  251 #define BV_SCANNED      0x00000001      /* VOP_FSYNC funcs mark written bufs */
  252 #define BV_BKGRDINPROG  0x00000002      /* Background write in progress */
  253 #define BV_BKGRDWAIT    0x00000004      /* Background write waiting */
  254 #define BV_BKGRDERR     0x00000008      /* Error from background write */
  255 
  256 #define PRINT_BUF_VFLAGS "\2\4bkgrderr\3bkgrdwait\2bkgrdinprog\1scanned"
  257 
  258 #ifdef _KERNEL
  259 /*
  260  * Buffer locking
  261  */
  262 extern const char *buf_wmesg;           /* Default buffer lock message */
  263 #define BUF_WMESG "bufwait"
  264 #include <sys/proc.h>                   /* XXX for curthread */
  265 #include <sys/mutex.h>
  266 
  267 /*
  268  * Initialize a lock.
  269  */
  270 #define BUF_LOCKINIT(bp)                                                \
  271         lockinit(&(bp)->b_lock, PRIBIO + 4, buf_wmesg, 0, 0)
  272 /*
  273  *
  274  * Get a lock sleeping non-interruptably until it becomes available.
  275  */
  276 #define BUF_LOCK(bp, locktype, interlock)                               \
  277         _lockmgr_args_rw(&(bp)->b_lock, (locktype), (interlock),        \
  278             LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT,         \
  279             LOCK_FILE, LOCK_LINE)
  280 
  281 /*
  282  * Get a lock sleeping with specified interruptably and timeout.
  283  */
  284 #define BUF_TIMELOCK(bp, locktype, interlock, wmesg, catch, timo)       \
  285         _lockmgr_args_rw(&(bp)->b_lock, (locktype) | LK_TIMELOCK,       \
  286             (interlock), (wmesg), (PRIBIO + 4) | (catch), (timo),       \
  287             LOCK_FILE, LOCK_LINE)
  288 
  289 /*
  290  * Release a lock. Only the acquiring process may free the lock unless
  291  * it has been handed off to biodone.
  292  */
  293 #define BUF_UNLOCK(bp) do {                                             \
  294         KASSERT(((bp)->b_flags & B_REMFREE) == 0,                       \
  295             ("BUF_UNLOCK %p while B_REMFREE is still set.", (bp)));     \
  296                                                                         \
  297         (void)_lockmgr_args(&(bp)->b_lock, LK_RELEASE, NULL,            \
  298             LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT,         \
  299             LOCK_FILE, LOCK_LINE);                                      \
  300 } while (0)
  301 
  302 /*
  303  * Check if a buffer lock is recursed.
  304  */
  305 #define BUF_LOCKRECURSED(bp)                                            \
  306         lockmgr_recursed(&(bp)->b_lock)
  307 
  308 /*
  309  * Check if a buffer lock is currently held.
  310  */
  311 #define BUF_ISLOCKED(bp)                                                \
  312         lockstatus(&(bp)->b_lock)
  313 /*
  314  * Free a buffer lock.
  315  */
  316 #define BUF_LOCKFREE(bp)                                                \
  317         lockdestroy(&(bp)->b_lock)
  318 
  319 /*
  320  * Print informations on a buffer lock.
  321  */
  322 #define BUF_LOCKPRINTINFO(bp)                                           \
  323         lockmgr_printinfo(&(bp)->b_lock)
  324 
  325 /*
  326  * Buffer lock assertions.
  327  */
  328 #if defined(INVARIANTS) && defined(INVARIANT_SUPPORT)
  329 #define BUF_ASSERT_LOCKED(bp)                                           \
  330         _lockmgr_assert(&(bp)->b_lock, KA_LOCKED, LOCK_FILE, LOCK_LINE)
  331 #define BUF_ASSERT_SLOCKED(bp)                                          \
  332         _lockmgr_assert(&(bp)->b_lock, KA_SLOCKED, LOCK_FILE, LOCK_LINE)
  333 #define BUF_ASSERT_XLOCKED(bp)                                          \
  334         _lockmgr_assert(&(bp)->b_lock, KA_XLOCKED, LOCK_FILE, LOCK_LINE)
  335 #define BUF_ASSERT_UNLOCKED(bp)                                         \
  336         _lockmgr_assert(&(bp)->b_lock, KA_UNLOCKED, LOCK_FILE, LOCK_LINE)
  337 #define BUF_ASSERT_HELD(bp)
  338 #define BUF_ASSERT_UNHELD(bp)
  339 #else
  340 #define BUF_ASSERT_LOCKED(bp)
  341 #define BUF_ASSERT_SLOCKED(bp)
  342 #define BUF_ASSERT_XLOCKED(bp)
  343 #define BUF_ASSERT_UNLOCKED(bp)
  344 #define BUF_ASSERT_HELD(bp)
  345 #define BUF_ASSERT_UNHELD(bp)
  346 #endif
  347 
  348 #ifdef _SYS_PROC_H_     /* Avoid #include <sys/proc.h> pollution */
  349 /*
  350  * When initiating asynchronous I/O, change ownership of the lock to the
  351  * kernel. Once done, the lock may legally released by biodone. The
  352  * original owning process can no longer acquire it recursively, but must
  353  * wait until the I/O is completed and the lock has been freed by biodone.
  354  */
  355 #define BUF_KERNPROC(bp)                                                \
  356         _lockmgr_disown(&(bp)->b_lock, LOCK_FILE, LOCK_LINE)
  357 #endif
  358 
  359 /*
  360  * Find out if the lock has waiters or not.
  361  */
  362 #define BUF_LOCKWAITERS(bp)                                             \
  363         lockmgr_waiters(&(bp)->b_lock)
  364 
  365 #endif /* _KERNEL */
  366 
  367 struct buf_queue_head {
  368         TAILQ_HEAD(buf_queue, buf) queue;
  369         daddr_t last_pblkno;
  370         struct  buf *insert_point;
  371         struct  buf *switch_point;
  372 };
  373 
  374 /*
  375  * This structure describes a clustered I/O. 
  376  */
  377 struct cluster_save {
  378         long    bs_bcount;              /* Saved b_bcount. */
  379         long    bs_bufsize;             /* Saved b_bufsize. */
  380         int     bs_nchildren;           /* Number of associated buffers. */
  381         struct buf **bs_children;       /* List of associated buffers. */
  382 };
  383 
  384 #ifdef _KERNEL
  385 
  386 static __inline int
  387 bwrite(struct buf *bp)
  388 {
  389 
  390         KASSERT(bp->b_bufobj != NULL, ("bwrite: no bufobj bp=%p", bp));
  391         KASSERT(bp->b_bufobj->bo_ops != NULL, ("bwrite: no bo_ops bp=%p", bp));
  392         KASSERT(bp->b_bufobj->bo_ops->bop_write != NULL,
  393             ("bwrite: no bop_write bp=%p", bp));
  394         return (BO_WRITE(bp->b_bufobj, bp));
  395 }
  396 
  397 static __inline void
  398 bstrategy(struct buf *bp)
  399 {
  400 
  401         KASSERT(bp->b_bufobj != NULL, ("bstrategy: no bufobj bp=%p", bp));
  402         KASSERT(bp->b_bufobj->bo_ops != NULL,
  403             ("bstrategy: no bo_ops bp=%p", bp));
  404         KASSERT(bp->b_bufobj->bo_ops->bop_strategy != NULL,
  405             ("bstrategy: no bop_strategy bp=%p", bp));
  406         BO_STRATEGY(bp->b_bufobj, bp);
  407 }
  408 
  409 static __inline void
  410 buf_start(struct buf *bp)
  411 {
  412         if (bioops.io_start)
  413                 (*bioops.io_start)(bp);
  414 }
  415 
  416 static __inline void
  417 buf_complete(struct buf *bp)
  418 {
  419         if (bioops.io_complete)
  420                 (*bioops.io_complete)(bp);
  421 }
  422 
  423 static __inline void
  424 buf_deallocate(struct buf *bp)
  425 {
  426         if (bioops.io_deallocate)
  427                 (*bioops.io_deallocate)(bp);
  428 }
  429 
  430 static __inline int
  431 buf_countdeps(struct buf *bp, int i)
  432 {
  433         if (bioops.io_countdeps)
  434                 return ((*bioops.io_countdeps)(bp, i));
  435         else
  436                 return (0);
  437 }
  438 
  439 #endif /* _KERNEL */
  440 
  441 /*
  442  * Zero out the buffer's data area.
  443  */
  444 #define clrbuf(bp) {                                                    \
  445         bzero((bp)->b_data, (u_int)(bp)->b_bcount);                     \
  446         (bp)->b_resid = 0;                                              \
  447 }
  448 
  449 /*
  450  * Flags for getblk's last parameter.
  451  */
  452 #define GB_LOCK_NOWAIT  0x0001          /* Fail if we block on a buf lock. */
  453 #define GB_NOCREAT      0x0002          /* Don't create a buf if not found. */
  454 #define GB_NOWAIT_BD    0x0004          /* Do not wait for bufdaemon. */
  455 #define GB_UNMAPPED     0x0008          /* Do not mmap buffer pages. */
  456 #define GB_KVAALLOC     0x0010          /* But allocate KVA. */
  457 
  458 #ifdef _KERNEL
  459 extern int      nbuf;                   /* The number of buffer headers */
  460 extern long     maxswzone;              /* Max KVA for swap structures */
  461 extern long     maxbcache;              /* Max KVA for buffer cache */
  462 extern int      maxbcachebuf;           /* Max buffer cache block size */
  463 extern long     runningbufspace;
  464 extern long     hibufspace;
  465 extern int      dirtybufthresh;
  466 extern int      bdwriteskip;
  467 extern int      dirtybufferflushes;
  468 extern int      altbufferflushes;
  469 extern int      nswbuf;                 /* Number of swap I/O buffer headers. */
  470 extern int      cluster_pbuf_freecnt;   /* Number of pbufs for clusters */
  471 extern int      vnode_pbuf_freecnt;     /* Number of pbufs for vnode pager */
  472 extern int      vnode_async_pbuf_freecnt; /* Number of pbufs for vnode pager,
  473                                              asynchronous reads */
  474 extern caddr_t  unmapped_buf;   /* Data address for unmapped buffers. */
  475 
  476 static inline int
  477 buf_mapped(struct buf *bp)
  478 {
  479 
  480         return (bp->b_data != unmapped_buf);
  481 }
  482 
  483 void    runningbufwakeup(struct buf *);
  484 void    waitrunningbufspace(void);
  485 caddr_t kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est);
  486 void    bufinit(void);
  487 void    bufshutdown(int);
  488 void    bdata2bio(struct buf *bp, struct bio *bip);
  489 void    bwillwrite(void);
  490 int     buf_dirty_count_severe(void);
  491 void    bremfree(struct buf *);
  492 void    bremfreef(struct buf *);        /* XXX Force bremfree, only for nfs. */
  493 #define bread(vp, blkno, size, cred, bpp) \
  494             breadn_flags(vp, blkno, size, NULL, NULL, 0, cred, 0, bpp)
  495 #define bread_gb(vp, blkno, size, cred, gbflags, bpp) \
  496             breadn_flags(vp, blkno, size, NULL, NULL, 0, cred, \
  497                 gbflags, bpp)
  498 #define breadn(vp, blkno, size, rablkno, rabsize, cnt, cred, bpp) \
  499             breadn_flags(vp, blkno, size, rablkno, rabsize, cnt, cred, 0, bpp)
  500 int     breadn_flags(struct vnode *, daddr_t, int, daddr_t *, int *, int,
  501             struct ucred *, int, struct buf **);
  502 void    breada(struct vnode *, daddr_t *, int *, int, struct ucred *);
  503 void    bdwrite(struct buf *);
  504 void    bawrite(struct buf *);
  505 void    babarrierwrite(struct buf *);
  506 int     bbarrierwrite(struct buf *);
  507 void    bdirty(struct buf *);
  508 void    bundirty(struct buf *);
  509 void    bufstrategy(struct bufobj *, struct buf *);
  510 void    brelse(struct buf *);
  511 void    bqrelse(struct buf *);
  512 int     vfs_bio_awrite(struct buf *);
  513 void    vfs_drain_busy_pages(struct buf *bp);
  514 struct buf *     getpbuf(int *);
  515 struct buf *incore(struct bufobj *, daddr_t);
  516 struct buf *gbincore(struct bufobj *, daddr_t);
  517 struct buf *getblk(struct vnode *, daddr_t, int, int, int, int);
  518 struct buf *geteblk(int, int);
  519 int     bufwait(struct buf *);
  520 int     bufwrite(struct buf *);
  521 void    bufdone(struct buf *);
  522 void    bufdone_finish(struct buf *);
  523 void    bd_speedup(void);
  524 
  525 int     cluster_read(struct vnode *, u_quad_t, daddr_t, long,
  526             struct ucred *, long, int, int, struct buf **);
  527 int     cluster_wbuild(struct vnode *, long, daddr_t, int, int);
  528 void    cluster_write(struct vnode *, struct buf *, u_quad_t, int, int);
  529 void    vfs_bio_brelse(struct buf *bp, int ioflags);
  530 void    vfs_bio_bzero_buf(struct buf *bp, int base, int size);
  531 void    vfs_bio_clrbuf(struct buf *);
  532 void    vfs_bio_set_flags(struct buf *bp, int ioflags);
  533 void    vfs_bio_set_valid(struct buf *, int base, int size);
  534 void    vfs_busy_pages(struct buf *, int clear_modify);
  535 void    vfs_unbusy_pages(struct buf *);
  536 int     vmapbuf(struct buf *, int);
  537 void    vunmapbuf(struct buf *);
  538 void    relpbuf(struct buf *, int *);
  539 void    brelvp(struct buf *);
  540 void    bgetvp(struct vnode *, struct buf *);
  541 void    pbgetbo(struct bufobj *bo, struct buf *bp);
  542 void    pbgetvp(struct vnode *, struct buf *);
  543 void    pbrelbo(struct buf *);
  544 void    pbrelvp(struct buf *);
  545 int     allocbuf(struct buf *bp, int size);
  546 void    reassignbuf(struct buf *);
  547 struct  buf *trypbuf(int *);
  548 void    bwait(struct buf *, u_char, const char *);
  549 void    bdone(struct buf *);
  550 void    bpin(struct buf *);
  551 void    bunpin(struct buf *);
  552 void    bunpin_wait(struct buf *);
  553 
  554 typedef daddr_t (vbg_get_lblkno_t)(struct vnode *, vm_ooffset_t);
  555 typedef int (vbg_get_blksize_t)(struct vnode *, daddr_t);
  556 int     vfs_bio_getpages(struct vnode *vp, struct vm_page **ma, int count,
  557             int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
  558             vbg_get_blksize_t get_blksize);
  559 
  560 #endif /* _KERNEL */
  561 
  562 #endif /* !_SYS_BUF_H_ */

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