lustre/mdc: comments on LOOKUP and PERM lock

Add more comments for MDS_INODELOCK_PERM and
MDS_INODELOCK_LOOKUP

Signed-off-by: wang di <di.wang@intel.com>
Reviewed-on: http://review.whamcloud.com/7937
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3240
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/include/lustre/lustre_idl.h b/drivers/staging/lustre/lustre/include/lustre/lustre_idl.h
index 4183a359f1f5356bd36f0a9f5fb8fad3c7423215..4c70c060b15870c15b0cbf436bc7aedcc2239dc4 100644 (file)
--- a/drivers/staging/lustre/lustre/include/lustre/lustre_idl.h
+++ b/drivers/staging/lustre/lustre/include/lustre/lustre_idl.h
@@ -2116,12 +2116,24 @@ extern void lustre_swab_generic_32s (__u32 *val);
 #define DISP_OPEN_LEASE      0x04000000
 
 /* INODE LOCK PARTS */
-#define MDS_INODELOCK_LOOKUP 0x000001       /* dentry, mode, owner, group */
-#define MDS_INODELOCK_UPDATE 0x000002       /* size, links, timestamps */
-#define MDS_INODELOCK_OPEN   0x000004       /* For opened files */
-#define MDS_INODELOCK_LAYOUT 0x000008       /* for layout */
-#define MDS_INODELOCK_PERM   0x000010       /* for permission */
-#define MDS_INODELOCK_XATTR  0x000020       /* extended attributes */
+#define MDS_INODELOCK_LOOKUP 0x000001  /* For namespace, dentry etc, and also
+                                        * was used to protect permission (mode,
+                                        * owner, group etc) before 2.4. */
+#define MDS_INODELOCK_UPDATE 0x000002  /* size, links, timestamps */
+#define MDS_INODELOCK_OPEN   0x000004  /* For opened files */
+#define MDS_INODELOCK_LAYOUT 0x000008  /* for layout */
+
+/* The PERM bit is added int 2.4, and it is used to protect permission(mode,
+ * owner, group, acl etc), so to separate the permission from LOOKUP lock.
+ * Because for remote directories(in DNE), these locks will be granted by
+ * different MDTs(different ldlm namespace).
+ *
+ * For local directory, MDT will always grant UPDATE_LOCK|PERM_LOCK together.
+ * For Remote directory, the master MDT, where the remote directory is, will
+ * grant UPDATE_LOCK|PERM_LOCK, and the remote MDT, where the name entry is,
+ * will grant LOOKUP_LOCK. */
+#define MDS_INODELOCK_PERM   0x000010
+#define MDS_INODELOCK_XATTR  0x000020  /* extended attributes */
 
 #define MDS_INODELOCK_MAXSHIFT 5
 /* This FULL lock is useful to take on unlink sort of operations */

diff --git a/drivers/staging/lustre/lustre/mdc/mdc_locks.c b/drivers/staging/lustre/lustre/mdc/mdc_locks.c
index 1336d4750c377ff1621af78bd2c8be36f7eabe93..d9017a579a322ce2dbde03ac7d3228700dcd4e71 100644 (file)
--- a/drivers/staging/lustre/lustre/mdc/mdc_locks.c
+++ b/drivers/staging/lustre/lustre/mdc/mdc_locks.c
@@ -1072,6 +1072,9 @@ int mdc_revalidate_lock(struct obd_export *exp, struct lookup_intent *it,
                         * locks, there's no easy way to match all of them here,
                         * so an extra RPC would be performed to fetch all
                         * of those bits at once for now. */
+                       /* For new MDTs(> 2.4), UPDATE|PERM should be enough,
+                        * but for old MDTs (< 2.4), permission is covered
+                        * by LOOKUP lock, so it needs to match all bits here.*/
                        policy.l_inodebits.bits = MDS_INODELOCK_UPDATE |
                                                  MDS_INODELOCK_LOOKUP |
                                                  MDS_INODELOCK_PERM;