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