lustre/lvfs/fsfilt.c

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