lustre/obdclass/fsfilt.c

   1 #define EXPORT_SYMTAB
   2 #define DEBUG_SUBSYSTEM S_FILTER
   3
   4 #include <linux/fs.h>
   5 #include <linux/jbd.h>
   6 #include <linux/module.h>
   7 #include <linux/kmod.h>
   8 #include <linux/slab.h>
   9 #include <linux/kp30.h>
  10 #include <linux/lustre_fsfilt.h>
  11
  12 LIST_HEAD(fsfilt_types);
  13
  14 static struct fsfilt_operations *fsfilt_search_type(const char *type)
  15 {
  16         struct fsfilt_operations *found;
  17         struct list_head *p;
  18
  19         list_for_each(p, &fsfilt_types) {
  20                 found = list_entry(p, struct fsfilt_operations, fs_list);
  21                 if (!strcmp(found->fs_type, type)) {
  22                         return found;
  23                 }
  24         }
  25         return NULL;
  26 }
  27
  28 int fsfilt_register_ops(struct fsfilt_operations *fs_ops)
  29 {
  30         struct fsfilt_operations *found;
  31
  32         /* lock fsfilt_types list */
  33         if ((found = fsfilt_search_type(fs_ops->fs_type))) {
  34                 if (found != fs_ops) {
  35                         CERROR("different operations for type %s\n",
  36                                fs_ops->fs_type);
  37                         /* unlock fsfilt_types list */
  38                         RETURN(-EEXIST);
  39                 }
  40         } else {
  41                 PORTAL_MODULE_USE;
  42                 list_add(&fs_ops->fs_list, &fsfilt_types);
  43         }
  44
  45         /* unlock fsfilt_types list */
  46         return 0;
  47 }
  48
  49 void fsfilt_unregister_ops(struct fsfilt_operations *fs_ops)
  50 {
  51         struct list_head *p;
  52
  53         /* lock fsfilt_types list */
  54         list_for_each(p, &fsfilt_types) {
  55                 struct fsfilt_operations *found;
  56
  57                 found = list_entry(p, typeof(*found), fs_list);
  58                 if (found == fs_ops) {
  59                         list_del(p);
  60                         PORTAL_MODULE_UNUSE;
  61                         break;
  62                 }
  63         }
  64         /* unlock fsfilt_types list */
  65 }
  66
  67 struct fsfilt_operations *fsfilt_get_ops(char *type)
  68 {
  69         struct fsfilt_operations *fs_ops;
  70
  71         /* lock fsfilt_types list */
  72         if (!(fs_ops = fsfilt_search_type(type))) {
  73                 char name[32];
  74                 int rc;
  75
  76                 snprintf(name, sizeof(name) - 1, "fsfilt_%s", type);
  77                 name[sizeof(name) - 1] = '\0';
  78
  79                 if ((rc = request_module(name))) {
  80                         fs_ops = fsfilt_search_type(type);
  81                         CDEBUG(D_INFO, "Loaded module '%s'\n", name);
  82                         if (!fs_ops)
  83                                 rc = -ENOENT;
  84                 }
  85
  86                 if (rc) {
  87                         CERROR("Can't find fsfilt_%s interface\n", name);
  88                         RETURN(ERR_PTR(rc));
  89                         /* unlock fsfilt_types list */
  90                 }
  91         }
  92         __MOD_INC_USE_COUNT(fs_ops->fs_owner);
  93         /* unlock fsfilt_types list */
  94
  95         return fs_ops;
  96 }
  97
  98 void fsfilt_put_ops(struct fsfilt_operations *fs_ops)
  99 {
 100         __MOD_DEC_USE_COUNT(fs_ops->fs_owner);
 101 }
 102
 103
 104 EXPORT_SYMBOL(fsfilt_register_ops);
 105 EXPORT_SYMBOL(fsfilt_unregister_ops);
 106 EXPORT_SYMBOL(fsfilt_get_ops);
 107 EXPORT_SYMBOL(fsfilt_put_ops);