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

     /*-
      * Copyright (c) 2014 Gleb Smirnoff <glebius@FreeBSD.org>
      * Copyright (c) 2003-2004 Alan L. Cox <alc@cs.rice.edu>
      * All rights reserved.
      *
      * 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 AUTHOR 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 AUTHOR 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.
     *
     * $FreeBSD$
     */
    
    #ifndef _SYS_SF_BUF_H_
    #define _SYS_SF_BUF_H_
    
    struct sfstat {                         /* sendfile statistics */
            uint64_t        sf_syscalls;    /* times sendfile was called */
            uint64_t        sf_noiocnt;     /* times sendfile didn't require I/O */
            uint64_t        sf_iocnt;       /* times sendfile had to do disk I/O */
            uint64_t        sf_pages_read;  /* pages read as part of a request */
            uint64_t        sf_pages_valid; /* pages were valid for a request */
            uint64_t        sf_rhpages_requested;   /* readahead pages requested */
            uint64_t        sf_rhpages_read;        /* readahead pages read */
            uint64_t        sf_busy;        /* times aborted on a busy page */
            uint64_t        sf_allocfail;   /* times sfbuf allocation failed */
            uint64_t        sf_allocwait;   /* times sfbuf allocation had to wait */
    };
    
    #ifdef _KERNEL
    #include <sys/types.h>
    #include <sys/systm.h>
    #include <sys/counter.h>
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <vm/vm_page.h>
    
    /*
     * Sf_bufs, or sendfile(2) buffers provide a vm_page that is mapped
     * into kernel address space. Note, that they aren't used only
     * by sendfile(2)!
     *
     * Sf_bufs could be implemented as a feature of vm_page_t, but that
     * would require growth of the structure. That's why they are implemented
     * as a separate hash indexed by vm_page address. Implementation lives in
     * kern/subr_sfbuf.c. Meanwhile, most 64-bit machines have a physical map,
     * so they don't require this hash at all, thus ignore subr_sfbuf.c.
     *
     * Different 32-bit architectures demand different requirements on sf_buf
     * hash and functions. They request features in machine/vmparam.h, which
     * enable parts of this file. They can also optionally provide helpers in
     * machine/sf_buf.h
     *
     * Defines are:
     * SFBUF                This machine requires sf_buf hash.
     *                      subr_sfbuf.c should be compiled.
     * SFBUF_CPUSET         This machine can perform SFB_CPUPRIVATE mappings,
     *                      that do no invalidate cache on the rest of CPUs.
     * SFBUF_NOMD           This machine doesn't have machine/sf_buf.h
     *
     * SFBUF_OPTIONAL_DIRECT_MAP    Value of this define is used as boolean
     *                              variable that tells whether machine is
     *                              capable of direct map or not at runtime.
     * SFBUF_MAP            This machine provides its own sf_buf_map() and
     *                      sf_buf_unmap().
     * SFBUF_PROCESS_PAGE   This machine provides sf_buf_process_page()
     *                      function.
     */
    
    #ifdef SFBUF
    #if defined(SMP) && defined(SFBUF_CPUSET)
    #include <sys/_cpuset.h>
    #endif
    #include <sys/queue.h>
    
    struct sf_buf {
            LIST_ENTRY(sf_buf)      list_entry;     /* list of buffers */
            TAILQ_ENTRY(sf_buf)     free_entry;     /* list of buffers */
            vm_page_t               m;              /* currently mapped page */
            vm_offset_t             kva;            /* va of mapping */
            int                     ref_count;      /* usage of this mapping */
    #if defined(SMP) && defined(SFBUF_CPUSET)
            cpuset_t                cpumask;        /* where mapping is valid */
   #endif
   };
   #else /* ! SFBUF */
   struct sf_buf;
   #endif /* SFBUF */
   
   #ifndef SFBUF_NOMD
   #include <machine/sf_buf.h>
   #endif
   #ifdef SFBUF_OPTIONAL_DIRECT_MAP
   #include <machine/md_var.h>
   #endif
   
   #ifdef SFBUF
   struct sf_buf *sf_buf_alloc(struct vm_page *, int);
   void sf_buf_free(struct sf_buf *);
   void sf_buf_ref(struct sf_buf *);
   
   static inline vm_offset_t
   sf_buf_kva(struct sf_buf *sf)
   {
   #ifdef SFBUF_OPTIONAL_DIRECT_MAP
           if (SFBUF_OPTIONAL_DIRECT_MAP)
                   return (SFBUF_PHYS_DMAP(VM_PAGE_TO_PHYS((vm_page_t)sf)));
   #endif
   
           return (sf->kva);
   }
   
   static inline vm_page_t
   sf_buf_page(struct sf_buf *sf)
   {
   #ifdef SFBUF_OPTIONAL_DIRECT_MAP
           if (SFBUF_OPTIONAL_DIRECT_MAP)
                   return ((vm_page_t)sf);
   #endif
   
           return (sf->m);
   }
   
   #ifndef SFBUF_MAP
   #include <vm/pmap.h>
   
   static inline void
   sf_buf_map(struct sf_buf *sf, int flags)
   {
   
           pmap_qenter(sf->kva, &sf->m, 1);
   }
   
   static inline int
   sf_buf_unmap(struct sf_buf *sf)
   {
   
           return (0);
   }
   #endif /* SFBUF_MAP */
   
   #if defined(SMP) && defined(SFBUF_CPUSET)
   void sf_buf_shootdown(struct sf_buf *, int);
   #endif
   
   #ifdef SFBUF_PROCESS_PAGE
   boolean_t sf_buf_process_page(vm_page_t, void (*)(struct sf_buf *));
   #endif
   
   #else /* ! SFBUF */
   
   static inline struct sf_buf *
   sf_buf_alloc(struct vm_page *m, int pri)
   {
   
           return ((struct sf_buf *)m);
   }
   
   static inline void
   sf_buf_free(struct sf_buf *sf)
   {
   }
   
   static inline void
   sf_buf_ref(struct sf_buf *sf)
   {
   }
   #endif /* SFBUF */
   
   /*
    * Options to sf_buf_alloc() are specified through its flags argument.  This
    * argument's value should be the result of a bitwise or'ing of one or more
    * of the following values.
    */
   #define SFB_CATCH       1               /* Check signals if the allocation
                                              sleeps. */
   #define SFB_CPUPRIVATE  2               /* Create a CPU private mapping. */
   #define SFB_DEFAULT     0
   #define SFB_NOWAIT      4               /* Return NULL if all bufs are used. */
   
   extern counter_u64_t sfstat[sizeof(struct sfstat) / sizeof(uint64_t)];
   #define SFSTAT_ADD(name, val)   \
       counter_u64_add(sfstat[offsetof(struct sfstat, name) / sizeof(uint64_t)],\
           (val))
   #define SFSTAT_INC(name)        SFSTAT_ADD(name, 1)
   #endif /* _KERNEL */
   #endif /* !_SYS_SF_BUF_H_ */

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