+ * the following set of functions are used to maintain per-thread
+ * cache of FID->ino mapping. this mechanism is needed to resolve
+ * FID to inode at dt_insert() which in turn stores ino in the
+ * directory entries to keep ldiskfs compatible with ext[34].
+ * due to locking-originated restrictions we can't lookup ino
+ * using LU cache (deadlock is possible). lookup using OI is quite
+ * expensive. so instead we maintain this cache and methods like
+ * dt_create() fill it. so in the majority of cases dt_insert() is
+ * able to find needed mapping in lockless manner.
+ */
+static struct osd_idmap_cache *
+osd_idc_find(const struct lu_env *env, struct osd_device *osd,
+ const struct lu_fid *fid)
+{
+ struct osd_thread_info *oti = osd_oti_get(env);
+ struct osd_idmap_cache *idc = oti->oti_ins_cache;
+ int i;
+ for (i = 0; i < oti->oti_ins_cache_used; i++) {
+ if (!lu_fid_eq(&idc[i].oic_fid, fid))
+ continue;
+ if (idc[i].oic_dev != osd)
+ continue;
+
+ return idc + i;
+ }
+
+ return NULL;
+}
+
+static struct osd_idmap_cache *
+osd_idc_add(const struct lu_env *env, struct osd_device *osd,
+ const struct lu_fid *fid)
+{
+ struct osd_thread_info *oti = osd_oti_get(env);
+ struct osd_idmap_cache *idc;
+ int i;
+
+ if (unlikely(oti->oti_ins_cache_used >= oti->oti_ins_cache_size)) {
+ i = oti->oti_ins_cache_size * 2;
+ if (i == 0)
+ i = OSD_INS_CACHE_SIZE;
+ OBD_ALLOC(idc, sizeof(*idc) * i);
+ if (idc == NULL)
+ return ERR_PTR(-ENOMEM);
+ if (oti->oti_ins_cache != NULL) {
+ memcpy(idc, oti->oti_ins_cache,
+ oti->oti_ins_cache_used * sizeof(*idc));
+ OBD_FREE(oti->oti_ins_cache,
+ oti->oti_ins_cache_used * sizeof(*idc));
+ }
+ oti->oti_ins_cache = idc;
+ oti->oti_ins_cache_size = i;
+ }
+
+ idc = oti->oti_ins_cache + oti->oti_ins_cache_used++;
+ idc->oic_fid = *fid;
+ idc->oic_dev = osd;
+ idc->oic_lid.oii_ino = 0;
+ idc->oic_lid.oii_gen = 0;
+ idc->oic_remote = 0;
+
+ return idc;
+}
+
+/*
+ * lookup mapping for the given fid in the cache, initialize a
+ * new one if not found. the initialization checks whether the
+ * object is local or remote. for local objects, OI is used to
+ * learn ino/generation. the function is used when the caller
+ * has no information about the object, e.g. at dt_insert().
+ */
+static struct osd_idmap_cache *
+osd_idc_find_or_init(const struct lu_env *env, struct osd_device *osd,
+ const struct lu_fid *fid)
+{
+ struct osd_idmap_cache *idc;
+ int rc;
+
+ idc = osd_idc_find(env, osd, fid);
+ LASSERT(!IS_ERR(idc));
+ if (idc != NULL)
+ return idc;
+
+ /* new mapping is needed */
+ idc = osd_idc_add(env, osd, fid);
+ if (IS_ERR(idc))
+ return idc;
+
+ /* initialize it */
+ rc = osd_remote_fid(env, osd, fid);
+ if (unlikely(rc < 0))
+ return ERR_PTR(rc);
+
+ if (rc == 0) {
+ /* the object is local, lookup in OI */
+ /* XXX: probably cheaper to lookup in LU first? */
+ rc = osd_oi_lookup(osd_oti_get(env), osd, fid,
+ &idc->oic_lid, 0);
+ if (unlikely(rc < 0)) {
+ CERROR("can't lookup: rc = %d\n", rc);
+ return ERR_PTR(rc);
+ }
+ } else {
+ /* the object is remote */
+ idc->oic_remote = 1;
+ }
+
+ return idc;
+}
+
+/*
+ * lookup mapping for given FID and fill it from the given object.
+ * the object is lolcal by definition.
+ */
+static int osd_idc_find_and_init(const struct lu_env *env,
+ struct osd_device *osd,
+ struct osd_object *obj)
+{
+ const struct lu_fid *fid = lu_object_fid(&obj->oo_dt.do_lu);
+ struct osd_idmap_cache *idc;
+
+ idc = osd_idc_find(env, osd, fid);
+ LASSERT(!IS_ERR(idc));
+ if (idc != NULL) {
+ if (obj->oo_inode == NULL)
+ return 0;
+ if (idc->oic_lid.oii_ino != obj->oo_inode->i_ino) {
+ LASSERT(idc->oic_lid.oii_ino == 0);
+ idc->oic_lid.oii_ino = obj->oo_inode->i_ino;
+ idc->oic_lid.oii_gen = obj->oo_inode->i_generation;
+ }
+ return 0;
+ }
+
+ /* new mapping is needed */
+ idc = osd_idc_add(env, osd, fid);
+ if (IS_ERR(idc))
+ return PTR_ERR(idc);
+
+ if (obj->oo_inode != NULL) {
+ idc->oic_lid.oii_ino = obj->oo_inode->i_ino;
+ idc->oic_lid.oii_gen = obj->oo_inode->i_generation;
+ }
+ return 0;
+}
+
+/*
git://git.whamcloud.com / fs / lustre-release.git / commitdiff