LU-13388 lod: unprotected access to component entries

a race is possible between setattr, which may want to traverse
the component set, and the layout_change, which may change the
component set if SEL is enabled. Take an UPDATE lock on layout
write operation.

HPE-bug-id: LUS-8146
Signed-off-by: Vitaly Fertman <c17818@cray.com>
Change-Id: Idf8a5c3d423707043153892f607cdd54099d9579
Reviewed-by: Alexey Lyashkov <c17817@cray.com>
Reviewed-by: Andriy Skulysh <c17819@cray.com>
Tested-by: Elena Gryaznova <c17455@cray.com>
Reviewed-on: https://es-gerrit.dev.cray.com/156681
Reviewed-on: https://review.whamcloud.com/38069
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/mdt/mdt_handler.c b/lustre/mdt/mdt_handler.c
index bfec8e1..4deb40e 100644 (file)
--- a/lustre/mdt/mdt_handler.c
+++ b/lustre/mdt/mdt_handler.c
@@ -1498,10 +1498,15 @@ int mdt_layout_change(struct mdt_thread_info *info, struct mdt_object *obj,
 
        if (rc > 0) {
                /* not resent */
+               __u64 lockpart = MDS_INODELOCK_LAYOUT;
+
+               /* take layout lock to prepare layout change */
+               if (layout->mlc_opc == MD_LAYOUT_WRITE)
+                       lockpart |= MDS_INODELOCK_UPDATE;
+
                mdt_lock_handle_init(lhc);
                mdt_lock_reg_init(lhc, LCK_EX);
-               rc = mdt_reint_object_lock(info, obj, lhc, MDS_INODELOCK_LAYOUT,
-                                          false);
+               rc = mdt_reint_object_lock(info, obj, lhc, lockpart, false);
                if (rc)
                        RETURN(rc);
        }