LU-13599 mdt: fix mti_big_lmm buffer usage

The mti_big_lmm buffer can be used just as temporary buffer
in some cases. It should drop mti_big_lmm_used flag after
that to avoid assertion in mdt_big_attr_get().

This fix is extracted from bigger patch of LU-11025 in
master branch.

Lustre-change: https://review.whamcloud.com/37284
Lustre-commit: a336d7c7

Signed-off-by: Mikhail Pershin <mpershin@whamcloud.com>
Change-Id: I3718d6c413ef1d5f8242e548868602ef6476006e
Reviewed-on: https://review.whamcloud.com/39521

Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Stephane Thiell <sthiell@stanford.edu>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

lustre/mdt/mdt_handler.c

@@ -921,8 +921,8 @@ int mdt_big_xattr_get(struct mdt_thread_info *info, struct mdt_object *o,
 	RETURN(rc);
 }
 
-int mdt_stripe_get(struct mdt_thread_info *info, struct mdt_object *o,
-		   struct md_attr *ma, const char *name)
+int __mdt_stripe_get(struct mdt_thread_info *info, struct mdt_object *o,
+		     struct md_attr *ma, const char *name)
 {
 	struct md_object *next = mdt_object_child(o);
 	struct lu_buf    *buf = &info->mti_buf;
@@ -998,6 +998,40 @@ got:
 	return rc;
 }
 
+int mdt_stripe_get(struct mdt_thread_info *info, struct mdt_object *o,
+		   struct md_attr *ma, const char *name)
+{
+	int rc;
+
+	if (!info->mti_big_lmm) {
+		OBD_ALLOC(info->mti_big_lmm, PAGE_SIZE);
+		if (!info->mti_big_lmm)
+			return -ENOMEM;
+		info->mti_big_lmmsize = PAGE_SIZE;
+	}
+
+	if (strcmp(name, XATTR_NAME_LOV) == 0) {
+		ma->ma_lmm = info->mti_big_lmm;
+		ma->ma_lmm_size = info->mti_big_lmmsize;
+		ma->ma_valid &= ~MA_LOV;
+	} else if (strcmp(name, XATTR_NAME_LMV) == 0) {
+		ma->ma_lmv = info->mti_big_lmm;
+		ma->ma_lmv_size = info->mti_big_lmmsize;
+		ma->ma_valid &= ~MA_LMV;
+	} else {
+		LBUG();
+	}
+
+	LASSERT(!info->mti_big_lmm_used);
+	rc = __mdt_stripe_get(info, o, ma, name);
+	/* since big_lmm is always used here, clear 'used' flag to avoid
+	 * assertion in mdt_big_xattr_get().
+	 */
+	info->mti_big_lmm_used = 0;
+
+	return rc;
+}
+
 int mdt_attr_get_pfid(struct mdt_thread_info *info, struct mdt_object *o,
 		      struct lu_fid *pfid)
 {
@@ -1082,19 +1116,19 @@ int mdt_attr_get_complex(struct mdt_thread_info *info,
 	}
 
 	if (need & MA_LOV && (S_ISREG(mode) || S_ISDIR(mode))) {
-		rc = mdt_stripe_get(info, o, ma, XATTR_NAME_LOV);
+		rc = __mdt_stripe_get(info, o, ma, XATTR_NAME_LOV);
 		if (rc)
 			GOTO(out, rc);
 	}
 
 	if (need & MA_LMV && S_ISDIR(mode)) {
-		rc = mdt_stripe_get(info, o, ma, XATTR_NAME_LMV);
+		rc = __mdt_stripe_get(info, o, ma, XATTR_NAME_LMV);
 		if (rc != 0)
 			GOTO(out, rc);
 	}
 
 	if (need & MA_LMV_DEF && S_ISDIR(mode)) {
-		rc = mdt_stripe_get(info, o, ma, XATTR_NAME_DEFAULT_LMV);
+		rc = __mdt_stripe_get(info, o, ma, XATTR_NAME_DEFAULT_LMV);
 		if (rc != 0)
 			GOTO(out, rc);
 	}

lustre/mdt/mdt_internal.h

@@ -835,6 +835,8 @@ int mdt_attr_get_complex(struct mdt_thread_info *info,
 			 struct mdt_object *o, struct md_attr *ma);
 int mdt_big_xattr_get(struct mdt_thread_info *info, struct mdt_object *o,
 		      const char *name);
+int __mdt_stripe_get(struct mdt_thread_info *info, struct mdt_object *o,
+		     struct md_attr *ma, const char *name);
 int mdt_stripe_get(struct mdt_thread_info *info, struct mdt_object *o,
 		   struct md_attr *ma, const char *name);
 int mdt_attr_get_pfid(struct mdt_thread_info *info, struct mdt_object *o,

lustre/mdt/mdt_reint.c

@@ -1739,9 +1739,6 @@ static int mdt_migrate_object_lock(struct mdt_thread_info *info,
 		if (S_ISDIR(lu_object_attr(&obj->mot_obj))) {
 			struct md_attr *ma = &info->mti_attr;
 
-			ma->ma_lmv = info->mti_big_lmm;
-			ma->ma_lmv_size = info->mti_big_lmmsize;
-			ma->ma_valid = 0;
 			rc = mdt_stripe_get(info, obj, ma, XATTR_NAME_LMV);
 			if (rc) {
 				mdt_object_unlock(info, obj, lh, rc);
@@ -2011,16 +2008,6 @@ static int mdt_reint_migrate(struct mdt_thread_info *info,
 	if (IS_ERR(pobj))
 		GOTO(unlock_rename, rc = PTR_ERR(pobj));
 
-	if (unlikely(!info->mti_big_lmm)) {
-		info->mti_big_lmmsize = lmv_mds_md_size(64, LMV_MAGIC);
-		OBD_ALLOC(info->mti_big_lmm, info->mti_big_lmmsize);
-		if (!info->mti_big_lmm)
-			GOTO(put_parent, rc = -ENOMEM);
-	}
-
-	ma->ma_lmv = info->mti_big_lmm;
-	ma->ma_lmv_size = info->mti_big_lmmsize;
-	ma->ma_valid = 0;
 	rc = mdt_stripe_get(info, pobj, ma, XATTR_NAME_LMV);
 	if (rc)
 		GOTO(put_parent, rc);
@@ -2056,9 +2043,6 @@ static int mdt_reint_migrate(struct mdt_thread_info *info,
 
 	/* TODO: DoM migration is not supported yet */
 	if (S_ISREG(lu_object_attr(&sobj->mot_obj))) {
-		ma->ma_lmm = info->mti_big_lmm;
-		ma->ma_lmm_size = info->mti_big_lmmsize;
-		ma->ma_valid = 0;
 		rc = mdt_stripe_get(info, sobj, ma, XATTR_NAME_LOV);
 		if (rc)
 			GOTO(put_source, rc);
@@ -2226,10 +2210,6 @@ static int mdt_rename_determine_lock_order(struct mdt_thread_info *info,
 		return 0;
 
 	/* check whether sobj and tobj are sibling stripes */
-	ma->ma_need = MA_LMV;
-	ma->ma_valid = 0;
-	ma->ma_lmv = (union lmv_mds_md *)info->mti_xattr_buf;
-	ma->ma_lmv_size = sizeof(info->mti_xattr_buf);
 	rc = mdt_stripe_get(info, sobj, ma, XATTR_NAME_LMV);
 	if (rc)
 		return rc;

lustre/mdt/mdt_xattr.c

@@ -345,14 +345,6 @@ static int mdt_dir_layout_shrink(struct mdt_thread_info *info)
 	    mdt->mdt_enable_remote_dir_gid != -1)
 		RETURN(-EPERM);
 
-	/* mti_big_lmm is used to save LMV, but it may be uninitialized. */
-	if (unlikely(!info->mti_big_lmm)) {
-		info->mti_big_lmmsize = lmv_mds_md_size(64, LMV_MAGIC);
-		OBD_ALLOC(info->mti_big_lmm, info->mti_big_lmmsize);
-		if (!info->mti_big_lmm)
-			RETURN(-ENOMEM);
-	}
-
 	obj = mdt_object_find(env, mdt, rr->rr_fid1);
 	if (IS_ERR(obj))
 		RETURN(PTR_ERR(obj));
@@ -396,9 +388,6 @@ static int mdt_dir_layout_shrink(struct mdt_thread_info *info)
 	if (rc)
 		GOTO(unlock_pobj, rc);
 
-	ma->ma_lmv = info->mti_big_lmm;
-	ma->ma_lmv_size = info->mti_big_lmmsize;
-	ma->ma_valid = 0;
 	rc = mdt_stripe_get(info, obj, ma, XATTR_NAME_LMV);
 	if (rc)
 		GOTO(unlock_obj, rc);