fs/reiser4/plugin/tail_policy.c

   1 /* Copyright 2001, 2002, 2003 by Hans Reiser, licensing governed by
   2  * reiser4/README */
   3
   4 /* Formatting policy plugins */
   5
   6 /*
   7  * Formatting policy plugin is used by object plugin (of regular file) to
   8  * convert file between two representations.
   9  *
  10  * Currently following policies are implemented:
  11  *  never store file in formatted nodes
  12  *  always store file in formatted nodes
  13  *  store file in formatted nodes if file is smaller than 4 blocks (default)
  14  */
  15
  16 #include "../tree.h"
  17 #include "../inode.h"
  18 #include "../super.h"
  19 #include "object.h"
  20 #include "plugin.h"
  21 #include "node/node.h"
  22 #include "plugin_header.h"
  23
  24 #include <linux/pagemap.h>
  25 #include <linux/fs.h>           /* For struct inode */
  26
  27 /**
  28  * have_formatting_never -
  29  * @inode:
  30  * @size:
  31  *
  32  *
  33  */
  34 /* Never store file's tail as direct item */
  35 /* Audited by: green(2002.06.12) */
  36 static int have_formatting_never(const struct inode *inode UNUSED_ARG
  37                       /* inode to operate on */ ,
  38                       loff_t size UNUSED_ARG /* new object size */ )
  39 {
  40         return 0;
  41 }
  42
  43 /* Always store file's tail as direct item */
  44 /* Audited by: green(2002.06.12) */
  45 static int
  46 have_formatting_always(const struct inode *inode UNUSED_ARG
  47                        /* inode to operate on */ ,
  48                        loff_t size UNUSED_ARG /* new object size */ )
  49 {
  50         return 1;
  51 }
  52
  53 /* This function makes test if we should store file denoted @inode as tails only or
  54    as extents only. */
  55 static int
  56 have_formatting_default(const struct inode *inode UNUSED_ARG
  57                         /* inode to operate on */ ,
  58                         loff_t size /* new object size */ )
  59 {
  60         assert("umka-1253", inode != NULL);
  61
  62         if (size > inode->i_sb->s_blocksize * 4)
  63                 return 0;
  64
  65         return 1;
  66 }
  67
  68 /* tail plugins */
  69 formatting_plugin formatting_plugins[LAST_TAIL_FORMATTING_ID] = {
  70         [NEVER_TAILS_FORMATTING_ID] = {
  71                 .h = {
  72                         .type_id = REISER4_FORMATTING_PLUGIN_TYPE,
  73                         .id = NEVER_TAILS_FORMATTING_ID,
  74                         .pops = NULL,
  75                         .label = "never",
  76                         .desc = "Never store file's tail",
  77                         .linkage = {NULL, NULL}
  78                 },
  79                 .have_tail = have_formatting_never
  80         },
  81         [ALWAYS_TAILS_FORMATTING_ID] = {
  82                 .h = {
  83                         .type_id = REISER4_FORMATTING_PLUGIN_TYPE,
  84                         .id = ALWAYS_TAILS_FORMATTING_ID,
  85                         .pops = NULL,
  86                         .label = "always",
  87                         .desc = "Always store file's tail",
  88                         .linkage = {NULL, NULL}
  89                 },
  90                 .have_tail = have_formatting_always
  91         },
  92         [SMALL_FILE_FORMATTING_ID] = {
  93                 .h = {
  94                         .type_id = REISER4_FORMATTING_PLUGIN_TYPE,
  95                         .id = SMALL_FILE_FORMATTING_ID,
  96                         .pops = NULL,
  97                         .label = "4blocks",
  98                         .desc = "store files shorter than 4 blocks in tail items",
  99                         .linkage = {NULL, NULL}
 100                 },
 101                 .have_tail = have_formatting_default
 102         }
 103 };
 104
 105 /*
 106  * Local variables:
 107  * c-indentation-style: "K&R"
 108  * mode-name: "LC"
 109  * c-basic-offset: 8
 110  * tab-width: 8
 111  * fill-column: 79
 112  * End:
 113  */