LU-5153 fld: lsf_lock in update_from_controller

[fs/lustre-release.git] / lustre / fld / fld_internal.h

diff --git a/lustre/fld/fld_internal.h b/lustre/fld/fld_internal.h
index 6b9c353..ae8dce1 100644 (file)
--- a/lustre/fld/fld_internal.h
+++ b/lustre/fld/fld_internal.h
@@ -35,6 +35,24 @@
  *
  * lustre/fld/fld_internal.h
  *
+ * Subsystem Description:
+ * FLD is FID Location Database, which stores where (IE, on which MDT)
+ * FIDs are located.
+ * The database is basically a record file, each record consists of a FID
+ * sequence range, MDT/OST index, and flags. The FLD for the whole FS
+ * is only stored on the sequence controller(MDT0) right now, but each target
+ * also has its local FLD, which only stores the local sequence.
+ *
+ * The FLD subsystem usually has two tasks:
+ * 1. maintain the database, i.e. when the sequence controller allocates
+ * new sequence ranges to some nodes, it will call the FLD API to insert the
+ * location information <sequence_range, node_index> in FLDB.
+ *
+ * 2. Handle requests from other nodes, i.e. if client needs to know where
+ * the FID is located, if it can not find the information in the local cache,
+ * it will send a FLD lookup RPC to the FLD service, and the FLD service will
+ * look up the FLDB entry and return the location information to client.
+ *
  * Author: Yury Umanets <umka@clusterfs.com>
  * Author: Tom WangDi <wangdi@clusterfs.com>
  */
@@ -68,11 +86,11 @@ struct lu_fld_hash {
 };
 
 struct fld_cache_entry {
-        cfs_list_t               fce_lru;
-        cfs_list_t               fce_list;
-        /**
-         * fld cache entries are sorted on range->lsr_start field. */
-        struct lu_seq_range      fce_range;
+       struct list_head        fce_lru;
+       struct list_head        fce_list;
+       /**
+        * fld cache entries are sorted on range->lsr_start field. */
+       struct lu_seq_range     fce_range;
 };
 
 struct fld_cache {
@@ -96,11 +114,11 @@ struct fld_cache {
 
         /**
          * LRU list fld entries. */
-        cfs_list_t               fci_lru;
+       struct list_head        fci_lru;
 
         /**
          * sorted fld entries. */
-        cfs_list_t               fci_entries_head;
+       struct list_head        fci_entries_head;
 
         /**
          * Cache statistics. */