module/os/linux/spl/spl-shrinker.c

   1 /*
   2  *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
   3  *  Copyright (C) 2007 The Regents of the University of California.
   4  *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
   5  *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
   6  *  UCRL-CODE-235197
   7  *
   8  *  This file is part of the SPL, Solaris Porting Layer.
   9  *
  10  *  The SPL is free software; you can redistribute it and/or modify it
  11  *  under the terms of the GNU General Public License as published by the
  12  *  Free Software Foundation; either version 2 of the License, or (at your
  13  *  option) any later version.
  14  *
  15  *  The SPL is distributed in the hope that it will be useful, but WITHOUT
  16  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  18  *  for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License along
  21  *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
  22  *
  23  *  Solaris Porting Layer (SPL) Shrinker Implementation.
  24  */
  25
  26 #include <sys/kmem.h>
  27 #include <sys/shrinker.h>
  28
  29 #ifdef HAVE_SINGLE_SHRINKER_CALLBACK
  30 /* 3.0-3.11: single shrink() callback, which we wrap to carry both functions */
  31 struct spl_shrinker_wrap {
  32         struct shrinker shrinker;
  33         spl_shrinker_cb countfunc;
  34         spl_shrinker_cb scanfunc;
  35 };
  36
  37 static int
  38 spl_shrinker_single_cb(struct shrinker *shrinker, struct shrink_control *sc)
  39 {
  40         struct spl_shrinker_wrap *sw = (struct spl_shrinker_wrap *)shrinker;
  41
  42         if (sc->nr_to_scan != 0)
  43                 (void) sw->scanfunc(&sw->shrinker, sc);
  44         return (sw->countfunc(&sw->shrinker, sc));
  45 }
  46 #endif
  47
  48 struct shrinker *
  49 spl_register_shrinker(const char *name, spl_shrinker_cb countfunc,
  50     spl_shrinker_cb scanfunc, int seek_cost)
  51 {
  52         struct shrinker *shrinker;
  53
  54         /* allocate shrinker */
  55 #if defined(HAVE_SHRINKER_REGISTER)
  56         /* 6.7: kernel will allocate the shrinker for us */
  57         shrinker = shrinker_alloc(0, name);
  58 #elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
  59         /* 3.12-6.6: we allocate the shrinker  */
  60         shrinker = kmem_zalloc(sizeof (struct shrinker), KM_SLEEP);
  61 #elif defined(HAVE_SINGLE_SHRINKER_CALLBACK)
  62         /* 3.0-3.11: allocate a wrapper */
  63         struct spl_shrinker_wrap *sw =
  64             kmem_zalloc(sizeof (struct spl_shrinker_wrap), KM_SLEEP);
  65         shrinker = &sw->shrinker;
  66 #else
  67         /* 2.x-2.6.22, or a newer shrinker API has been introduced. */
  68 #error "Unknown shrinker API"
  69 #endif
  70
  71         if (shrinker == NULL)
  72                 return (NULL);
  73
  74         /* set callbacks */
  75 #ifdef HAVE_SINGLE_SHRINKER_CALLBACK
  76         sw->countfunc = countfunc;
  77         sw->scanfunc = scanfunc;
  78         shrinker->shrink = spl_shrinker_single_cb;
  79 #else
  80         shrinker->count_objects = countfunc;
  81         shrinker->scan_objects = scanfunc;
  82 #endif
  83
  84         /* set params */
  85         shrinker->seeks = seek_cost;
  86
  87         /* register with kernel */
  88 #if defined(HAVE_SHRINKER_REGISTER)
  89         shrinker_register(shrinker);
  90 #elif defined(HAVE_REGISTER_SHRINKER_VARARG)
  91         register_shrinker(shrinker, name);
  92 #else
  93         register_shrinker(shrinker);
  94 #endif
  95
  96         return (shrinker);
  97 }
  98 EXPORT_SYMBOL(spl_register_shrinker);
  99
 100 void
 101 spl_unregister_shrinker(struct shrinker *shrinker)
 102 {
 103 #if defined(HAVE_SHRINKER_REGISTER)
 104         shrinker_free(shrinker);
 105 #elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
 106         unregister_shrinker(shrinker);
 107         kmem_free(shrinker, sizeof (struct shrinker));
 108 #elif defined(HAVE_SINGLE_SHRINKER_CALLBACK)
 109         unregister_shrinker(shrinker);
 110         kmem_free(shrinker, sizeof (struct spl_shrinker_wrap));
 111 #else
 112 #error "Unknown shrinker API"
 113 #endif
 114 }
 115 EXPORT_SYMBOL(spl_unregister_shrinker);