staging/lustre/llite: Solve a race to access lli_has_smd in read case

In vvp_io_read_lock(), it used to decide if to add read lock by
checking lli_has_smd. Accessing lli_has_smd is racy when an empty
file is turned into raid0, therefore, it may result in read requests
are issued without corresponding lock.
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-on: http://review.whamcloud.com/12139
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5062Reviewed-by: Bobi Jam <bobijam@gmail.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/include/lclient.h

@@ -325,6 +325,7 @@ void ccc_lock_fini(const struct lu_env *env, struct cl_lock_slice *slice);
 int ccc_lock_enqueue(const struct lu_env *env,
 		     const struct cl_lock_slice *slice,
 		     struct cl_io *io, __u32 enqflags);
+int ccc_lock_use(const struct lu_env *env, const struct cl_lock_slice *slice);
 int ccc_lock_unuse(const struct lu_env *env, const struct cl_lock_slice *slice);
 int ccc_lock_wait(const struct lu_env *env, const struct cl_lock_slice *slice);
 int ccc_lock_fits_into(const struct lu_env *env,

drivers/staging/lustre/lustre/lclient/lcommon_cl.c

@@ -586,6 +586,12 @@ int ccc_lock_enqueue(const struct lu_env *env,
 	return 0;
 }
 
+int ccc_lock_use(const struct lu_env *env, const struct cl_lock_slice *slice)
+{
+	CLOBINVRNT(env, slice->cls_obj, ccc_object_invariant(slice->cls_obj));
+	return 0;
+}
+
 int ccc_lock_unuse(const struct lu_env *env, const struct cl_lock_slice *slice)
 {
 	CLOBINVRNT(env, slice->cls_obj, ccc_object_invariant(slice->cls_obj));

drivers/staging/lustre/lustre/llite/vvp_io.c

@@ -307,18 +307,13 @@ static int vvp_io_rw_lock(const struct lu_env *env, struct cl_io *io,
 static int vvp_io_read_lock(const struct lu_env *env,
 			    const struct cl_io_slice *ios)
 {
-	struct cl_io	 *io  = ios->cis_io;
-	struct ll_inode_info *lli = ll_i2info(ccc_object_inode(io->ci_obj));
+	struct cl_io	 *io = ios->cis_io;
+	struct cl_io_rw_common *rd = &io->u.ci_rd.rd;
 	int result;
 
-	/* XXX: Layer violation, we shouldn't see lsm at llite level. */
-	if (lli->lli_has_smd) /* lsm-less file doesn't need to lock */
-		result = vvp_io_rw_lock(env, io, CLM_READ,
-					io->u.ci_rd.rd.crw_pos,
-					io->u.ci_rd.rd.crw_pos +
-					io->u.ci_rd.rd.crw_count - 1);
-	else
-		result = 0;
+	result = vvp_io_rw_lock(env, io, CLM_READ, rd->crw_pos,
+				rd->crw_pos + rd->crw_count - 1);
+
 	return result;
 }
 

drivers/staging/lustre/lustre/llite/vvp_lock.c

@@ -71,6 +71,7 @@ static const struct cl_lock_operations vvp_lock_ops = {
 	.clo_fini      = ccc_lock_fini,
 	.clo_enqueue   = ccc_lock_enqueue,
 	.clo_wait      = ccc_lock_wait,
+	.clo_use       = ccc_lock_use,
 	.clo_unuse     = ccc_lock_unuse,
 	.clo_fits_into = ccc_lock_fits_into,
 	.clo_state     = ccc_lock_state,