X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=lustre%2Flod%2Flod_dev.c;h=96d2ac9c13a0544d272168b1e22bbd36a47e0223;hb=0de931bb0c66f397a0d9f4b66830cb1050015c9b;hp=e63c6ed1f35c1f8d6efa56f360310de599bfee49;hpb=8d3c7316fc94297e1d92f4ec31cf941a389f6f82;p=fs%2Flustre-release.git

diff --git a/lustre/lod/lod_dev.c b/lustre/lod/lod_dev.c
index e63c6ed..96d2ac9 100644
--- a/lustre/lod/lod_dev.c
+++ b/lustre/lod/lod_dev.c
@@ -37,6 +37,56 @@
  * Author: Alex Zhuravlev <alexey.zhuravlev@intel.com>
  * Author: Mikhail Pershin <mike.pershin@intel.com>
  */
+/**
+ * The Logical Object Device (LOD) layer manages access to striped
+ * objects (both regular files and directories). It implements the DT
+ * device and object APIs and is responsible for creating, storing,
+ * and loading striping information as an extended attribute of the
+ * underlying OSD object. LOD is the server side analog of the LOV and
+ * LMV layers on the client side.
+ *
+ * Metadata LU object stack (layers of the same compound LU object,
+ * all have the same FID):
+ *
+ *        MDT
+ *         |      MD API
+ *        MDD
+ *         |      DT API
+ *        LOD
+ *       /   \    DT API
+ *     OSD   OSP
+ *
+ * During LOD object initialization the localness or remoteness of the
+ * object FID dictates the choice between OSD and OSP.
+ *
+ * An LOD object (file or directory) with N stripes (each has a
+ * different FID):
+ *
+ *          LOD
+ *           |
+ *   +---+---+---+...+
+ *   |   |   |   |   |
+ *   S0  S1  S2  S3  S(N-1)  OS[DP] objects, seen as DT objects by LOD
+ *
+ * When upper layers must access an object's stripes (which are
+ * themselves OST or MDT LU objects) LOD finds these objects by their
+ * FIDs and stores them as an array of DT object pointers on the
+ * object. Declarations and operations on LOD objects are received by
+ * LOD (as DT object operations) and performed on the underlying
+ * OS[DP] object and (as needed) on the stripes. From the perspective
+ * of LOD, a stripe-less file (created by mknod() or open with
+ * O_LOV_DELAY_CREATE) is an object which does not yet have stripes,
+ * while a non-striped directory (created by mkdir()) is an object
+ * which will never have stripes.
+ *
+ * The LOD layer also implements a small subset of the OBD device API
+ * to support MDT stack initialization and finalization (an MDD device
+ * connects and disconnects itself to and from the underlying LOD
+ * device), and pool management. In turn LOD uses the OBD device API
+ * to connect it self to the underlying OSD, and to connect itself to
+ * OSP devices representing the MDTs and OSTs that bear the stripes of
+ * its objects.
+ */
 
 #define DEBUG_SUBSYSTEM S_MDS
 
@@ -142,7 +192,7 @@ static int lod_cleanup_desc_tgts(const struct lu_env *env,
 {
 	struct lu_device  *next;
 	int rc = 0;
-	int i;
+	unsigned int i;
 
 	lod_getref(ltd);
 	if (ltd->ltd_tgts_size <= 0) {
@@ -335,7 +385,8 @@ static int lod_recovery_complete(const struct lu_env *env,
 {
 	struct lod_device   *lod = lu2lod_dev(dev);
 	struct lu_device    *next = &lod->lod_child->dd_lu_dev;
-	int		     i, rc;
+	unsigned int	     i;
+	int		     rc;
 	ENTRY;
 
 	LASSERT(lod->lod_recovery_completed == 0);
@@ -469,7 +520,8 @@ static int lod_sync(const struct lu_env *env, struct dt_device *dev)
 {
 	struct lod_device   *lod = dt2lod_dev(dev);
 	struct lod_ost_desc *ost;
-	int                  rc = 0, i;
+	unsigned int         i;
+	int                  rc = 0;
 	ENTRY;
 
 	lod_getref(&lod->lod_ost_descs);
@@ -814,6 +866,7 @@ static void lod_key_fini(const struct lu_context *ctx,
 		info->lti_ea_store = NULL;
 		info->lti_ea_store_size = 0;
 	}
+	lu_buf_free(&info->lti_linkea_buf);
 	OBD_FREE_PTR(info);
 }
 
@@ -852,7 +905,8 @@ static int lod_obd_get_info(const struct lu_env *env, struct obd_export *exp,
 		struct obd_device	*obd = exp->exp_obd;
 		struct lod_device	*d;
 		struct lod_ost_desc	*ost;
-		int			i, rc = 1;
+		unsigned int		i;
+		int			rc = 1;
 
 		if (!obd->obd_set_up || obd->obd_stopping)
 			RETURN(-EAGAIN);