fs/reiser4/plugin/dir/hashed_dir.c

   1 /* Copyright 2001, 2002, 2003, 2004 by Hans Reiser, licensing governed by
   2  * reiser4/README */
   3
   4 /* Directory plugin using hashes (see fs/reiser4/plugin/hash.c) to map file
   5    names to the files. */
   6
   7 /*
   8  * Hashed directory logically consists of persistent directory
   9  * entries. Directory entry is a pair of a file name and a key of stat-data of
  10  * a file that has this name in the given directory.
  11  *
  12  * Directory entries are stored in the tree in the form of directory
  13  * items. Directory item should implement dir_entry_ops portion of item plugin
  14  * interface (see plugin/item/item.h). Hashed directory interacts with
  15  * directory item plugin exclusively through dir_entry_ops operations.
  16  *
  17  * Currently there are two implementations of directory items: "simple
  18  * directory item" (plugin/item/sde.[ch]), and "compound directory item"
  19  * (plugin/item/cde.[ch]) with the latter being the default.
  20  *
  21  * There is, however some delicate way through which directory code interferes
  22  * with item plugin: key assignment policy. A key for a directory item is
  23  * chosen by directory code, and as described in kassign.c, this key contains
  24  * a portion of file name. Directory item uses this knowledge to avoid storing
  25  * this portion of file name twice: in the key and in the directory item body.
  26  *
  27  */
  28
  29 #include "../../inode.h"
  30
  31 void complete_entry_key(const struct inode *, const char *name,
  32                         int len, reiser4_key * result);
  33
  34 /* this is implementation of build_entry_key method of dir
  35    plugin for HASHED_DIR_PLUGIN_ID
  36  */
  37 void build_entry_key_hashed(const struct inode *dir,    /* directory where entry is
  38                                                          * (or will be) in.*/
  39                             const struct qstr *qname,   /* name of file referenced
  40                                                          * by this entry */
  41                             reiser4_key * result        /* resulting key of directory
  42                                                          * entry */ )
  43 {
  44         const char *name;
  45         int len;
  46
  47         assert("nikita-1139", dir != NULL);
  48         assert("nikita-1140", qname != NULL);
  49         assert("nikita-1141", qname->name != NULL);
  50         assert("nikita-1142", result != NULL);
  51
  52         name = qname->name;
  53         len = qname->len;
  54
  55         assert("nikita-2867", strlen(name) == len);
  56
  57         reiser4_key_init(result);
  58         /* locality of directory entry's key is objectid of parent
  59            directory */
  60         set_key_locality(result, get_inode_oid(dir));
  61         /* minor packing locality is constant */
  62         set_key_type(result, KEY_FILE_NAME_MINOR);
  63         /* dot is special case---we always want it to be first entry in
  64            a directory. Actually, we just want to have smallest
  65            directory entry.
  66          */
  67         if (len == 1 && name[0] == '.')
  68                 return;
  69
  70         /* initialize part of entry key which depends on file name */
  71         complete_entry_key(dir, name, len, result);
  72 }
  73
  74 /* Local variables:
  75    c-indentation-style: "K&R"
  76    mode-name: "LC"
  77    c-basic-offset: 8
  78    tab-width: 8
  79    fill-column: 120
  80    End:
  81 */