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2024-01-05 071106ecf68c401173c58808b1cf5f68cc50d390 
 kernel/fs/overlayfs/util.c
....@@ -1,10 +1,7 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  * Copyright (C) 2011 Novell Inc.
34  * Copyright (C) 2016 Red Hat, Inc.
4
- *
5
- * This program is free software; you can redistribute it and/or modify it
6
- * under the terms of the GNU General Public License version 2 as published by
7
- * the Free Software Foundation.
85  */
96 
107 #include <linux/fs.h>
....@@ -21,13 +18,13 @@
2118 int ovl_want_write(struct dentry *dentry)
2219 {
2320 	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
24
-	return mnt_want_write(ofs->upper_mnt);
21
+	return mnt_want_write(ovl_upper_mnt(ofs));
2522 }
2623 
2724 void ovl_drop_write(struct dentry *dentry)
2825 {
2926 	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
30
-	mnt_drop_write(ofs->upper_mnt);
27
+	mnt_drop_write(ovl_upper_mnt(ofs));
3128 }
3229 
3330 struct dentry *ovl_workdir(struct dentry *dentry)
....@@ -45,28 +42,10 @@
4542 	return override_creds(ofs->creator_cred);
4643 }
4744 
48
-void ovl_revert_creds(const struct cred *old_cred)
45
+void ovl_revert_creds(struct super_block *sb, const struct cred *old_cred)
4946 {
5047 	if (old_cred)
5148 		revert_creds(old_cred);
52
-}
53
-
54
-ssize_t ovl_vfs_getxattr(struct dentry *dentry, const char *name, void *buf,
55
-			 size_t size)
56
-{
57
-	return __vfs_getxattr(dentry, d_inode(dentry), name, buf, size);
58
-}
59
-
60
-struct super_block *ovl_same_sb(struct super_block *sb)
61
-{
62
-	struct ovl_fs *ofs = sb->s_fs_info;
63
-
64
-	if (!ofs->numlowerfs)
65
-		return ofs->upper_mnt->mnt_sb;
66
-	else if (ofs->numlowerfs == 1 && !ofs->upper_mnt)
67
-		return ofs->lower_fs[0].sb;
68
-	else
69
-		return NULL;
7049 }
7150 
7251 /*
....@@ -79,8 +58,7 @@
7958  */
8059 int ovl_can_decode_fh(struct super_block *sb)
8160 {
82
-	if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry ||
83
-	    uuid_is_null(&sb->s_uuid))
61
+	if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry)
8462 		return 0;
8563 
8664 	return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
....@@ -120,11 +98,43 @@
12098 	return oe;
12199 }
122100 
101
+#define OVL_D_REVALIDATE (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE)
102
+
123103 bool ovl_dentry_remote(struct dentry *dentry)
124104 {
125
-	return dentry->d_flags &
126
-		(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
127
-		 DCACHE_OP_REAL);
105
+	return dentry->d_flags & OVL_D_REVALIDATE;
106
+}
107
+
108
+void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry)
109
+{
110
+	if (!ovl_dentry_remote(realdentry))
111
+		return;
112
+
113
+	spin_lock(&dentry->d_lock);
114
+	dentry->d_flags |= realdentry->d_flags & OVL_D_REVALIDATE;
115
+	spin_unlock(&dentry->d_lock);
116
+}
117
+
118
+void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry)
119
+{
120
+	return ovl_dentry_init_flags(dentry, upperdentry, OVL_D_REVALIDATE);
121
+}
122
+
123
+void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
124
+			   unsigned int mask)
125
+{
126
+	struct ovl_entry *oe = OVL_E(dentry);
127
+	unsigned int i, flags = 0;
128
+
129
+	if (upperdentry)
130
+		flags |= upperdentry->d_flags;
131
+	for (i = 0; i < oe->numlower; i++)
132
+		flags |= oe->lowerstack[i].dentry->d_flags;
133
+
134
+	spin_lock(&dentry->d_lock);
135
+	dentry->d_flags &= ~mask;
136
+	dentry->d_flags |= flags & mask;
137
+	spin_unlock(&dentry->d_lock);
128138 }
129139 
130140 bool ovl_dentry_weird(struct dentry *dentry)
....@@ -164,7 +174,7 @@
164174 {
165175 	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
166176 
167
-	path->mnt = ofs->upper_mnt;
177
+	path->mnt = ovl_upper_mnt(ofs);
168178 	path->dentry = ovl_dentry_upper(dentry);
169179 }
170180 
....@@ -216,7 +226,7 @@
216226 	return oe->numlower ? oe->lowerstack[0].dentry : NULL;
217227 }
218228 
219
-struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
229
+const struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
220230 {
221231 	struct ovl_entry *oe = dentry->d_fsdata;
222232 
....@@ -416,24 +426,6 @@
416426 	oi->redirect = redirect;
417427 }
418428 
419
-void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
420
-		    struct dentry *lowerdentry, struct dentry *lowerdata)
421
-{
422
-	struct inode *realinode = d_inode(upperdentry ?: lowerdentry);
423
-
424
-	if (upperdentry)
425
-		OVL_I(inode)->__upperdentry = upperdentry;
426
-	if (lowerdentry)
427
-		OVL_I(inode)->lower = igrab(d_inode(lowerdentry));
428
-	if (lowerdata)
429
-		OVL_I(inode)->lowerdata = igrab(d_inode(lowerdata));
430
-
431
-	ovl_copyattr(realinode, inode);
432
-	ovl_copyflags(realinode, inode);
433
-	if (!inode->i_ino)
434
-		inode->i_ino = realinode->i_ino;
435
-}
436
-
437429 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
438430 {
439431 	struct inode *upperinode = d_inode(upperdentry);
....@@ -446,25 +438,25 @@
446438 	smp_wmb();
447439 	OVL_I(inode)->__upperdentry = upperdentry;
448440 	if (inode_unhashed(inode)) {
449
-		if (!inode->i_ino)
450
-			inode->i_ino = upperinode->i_ino;
451441 		inode->i_private = upperinode;
452442 		__insert_inode_hash(inode, (unsigned long) upperinode);
453443 	}
454444 }
455445 
456
-static void ovl_dentry_version_inc(struct dentry *dentry, bool impurity)
446
+static void ovl_dir_version_inc(struct dentry *dentry, bool impurity)
457447 {
458448 	struct inode *inode = d_inode(dentry);
459449 
460450 	WARN_ON(!inode_is_locked(inode));
451
+	WARN_ON(!d_is_dir(dentry));
461452 	/*
462
-	 * Version is used by readdir code to keep cache consistent.  For merge
463
-	 * dirs all changes need to be noted.  For non-merge dirs, cache only
464
-	 * contains impure (ones which have been copied up and have origins)
465
-	 * entries, so only need to note changes to impure entries.
453
+	 * Version is used by readdir code to keep cache consistent.
454
+	 * For merge dirs (or dirs with origin) all changes need to be noted.
455
+	 * For non-merge dirs, cache contains only impure entries (i.e. ones
456
+	 * which have been copied up and have origins), so only need to note
457
+	 * changes to impure entries.
466458 	 */
467
-	if (OVL_TYPE_MERGE(ovl_path_type(dentry)) || impurity)
459
+	if (!ovl_dir_is_real(dentry) || impurity)
468460 		OVL_I(inode)->version++;
469461 }
470462 
....@@ -473,7 +465,7 @@
473465 	/* Copy mtime/ctime */
474466 	ovl_copyattr(d_inode(ovl_dentry_upper(dentry)), d_inode(dentry));
475467 
476
-	ovl_dentry_version_inc(dentry, impurity);
468
+	ovl_dir_version_inc(dentry, impurity);
477469 }
478470 
479471 u64 ovl_dentry_version_get(struct dentry *dentry)
....@@ -493,7 +485,32 @@
493485 
494486 struct file *ovl_path_open(struct path *path, int flags)
495487 {
496
-	return dentry_open(path, flags | O_NOATIME, current_cred());
488
+	struct inode *inode = d_inode(path->dentry);
489
+	int err, acc_mode;
490
+
491
+	if (flags & ~(O_ACCMODE | O_LARGEFILE))
492
+		BUG();
493
+
494
+	switch (flags & O_ACCMODE) {
495
+	case O_RDONLY:
496
+		acc_mode = MAY_READ;
497
+		break;
498
+	case O_WRONLY:
499
+		acc_mode = MAY_WRITE;
500
+		break;
501
+	default:
502
+		BUG();
503
+	}
504
+
505
+	err = inode_permission(inode, acc_mode | MAY_OPEN);
506
+	if (err)
507
+		return ERR_PTR(err);
508
+
509
+	/* O_NOATIME is an optimization, don't fail if not permitted */
510
+	if (inode_owner_or_capable(inode))
511
+		flags |= O_NOATIME;
512
+
513
+	return dentry_open(path, flags, current_cred());
497514 }
498515 
499516 /* Caller should hold ovl_inode->lock */
....@@ -536,13 +553,13 @@
536553 
537554 int ovl_copy_up_start(struct dentry *dentry, int flags)
538555 {
539
-	struct ovl_inode *oi = OVL_I(d_inode(dentry));
556
+	struct inode *inode = d_inode(dentry);
540557 	int err;
541558 
542
-	err = mutex_lock_interruptible(&oi->lock);
559
+	err = ovl_inode_lock_interruptible(inode);
543560 	if (!err && ovl_already_copied_up_locked(dentry, flags)) {
544561 		err = 1; /* Already copied up */
545
-		mutex_unlock(&oi->lock);
562
+		ovl_inode_unlock(inode);
546563 	}
547564 
548565 	return err;
....@@ -550,14 +567,14 @@
550567 
551568 void ovl_copy_up_end(struct dentry *dentry)
552569 {
553
-	mutex_unlock(&OVL_I(d_inode(dentry))->lock);
570
+	ovl_inode_unlock(d_inode(dentry));
554571 }
555572 
556
-bool ovl_check_origin_xattr(struct dentry *dentry)
573
+bool ovl_check_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry)
557574 {
558575 	ssize_t res;
559576 
560
-	res = ovl_vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
577
+	res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_ORIGIN, NULL, 0);
561578 
562579 	/* Zero size value means "copied up but origin unknown" */
563580 	if (res >= 0)
....@@ -566,7 +583,8 @@
566583 	return false;
567584 }
568585 
569
-bool ovl_check_dir_xattr(struct dentry *dentry, const char *name)
586
+bool ovl_check_dir_xattr(struct super_block *sb, struct dentry *dentry,
587
+			 enum ovl_xattr ox)
570588 {
571589 	ssize_t res;
572590 	char val;
....@@ -574,15 +592,36 @@
574592 	if (!d_is_dir(dentry))
575593 		return false;
576594 
577
-	res = ovl_vfs_getxattr(dentry, name, &val, 1);
595
+	res = ovl_do_getxattr(OVL_FS(sb), dentry, ox, &val, 1);
578596 	if (res == 1 && val == 'y')
579597 		return true;
580598 
581599 	return false;
582600 }
583601 
602
+#define OVL_XATTR_OPAQUE_POSTFIX	"opaque"
603
+#define OVL_XATTR_REDIRECT_POSTFIX	"redirect"
604
+#define OVL_XATTR_ORIGIN_POSTFIX	"origin"
605
+#define OVL_XATTR_IMPURE_POSTFIX	"impure"
606
+#define OVL_XATTR_NLINK_POSTFIX		"nlink"
607
+#define OVL_XATTR_UPPER_POSTFIX		"upper"
608
+#define OVL_XATTR_METACOPY_POSTFIX	"metacopy"
609
+
610
+#define OVL_XATTR_TAB_ENTRY(x) \
611
+	[x] = OVL_XATTR_PREFIX x ## _POSTFIX
612
+
613
+const char *ovl_xattr_table[] = {
614
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_OPAQUE),
615
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_REDIRECT),
616
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_ORIGIN),
617
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_IMPURE),
618
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_NLINK),
619
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_UPPER),
620
+	OVL_XATTR_TAB_ENTRY(OVL_XATTR_METACOPY),
621
+};
622
+
584623 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
585
-		       const char *name, const void *value, size_t size,
624
+		       enum ovl_xattr ox, const void *value, size_t size,
586625 		       int xerr)
587626 {
588627 	int err;
....@@ -591,10 +630,10 @@
591630 	if (ofs->noxattr)
592631 		return xerr;
593632 
594
-	err = ovl_do_setxattr(upperdentry, name, value, size, 0);
633
+	err = ovl_do_setxattr(ofs, upperdentry, ox, value, size);
595634 
596635 	if (err == -EOPNOTSUPP) {
597
-		pr_warn("overlayfs: cannot set %s xattr on upper\n", name);
636
+		pr_warn("cannot set %s xattr on upper\n", ovl_xattr(ofs, ox));
598637 		ofs->noxattr = true;
599638 		return xerr;
600639 	}
....@@ -619,21 +658,6 @@
619658 		ovl_set_flag(OVL_IMPURE, d_inode(dentry));
620659 
621660 	return err;
622
-}
623
-
624
-void ovl_set_flag(unsigned long flag, struct inode *inode)
625
-{
626
-	set_bit(flag, &OVL_I(inode)->flags);
627
-}
628
-
629
-void ovl_clear_flag(unsigned long flag, struct inode *inode)
630
-{
631
-	clear_bit(flag, &OVL_I(inode)->flags);
632
-}
633
-
634
-bool ovl_test_flag(unsigned long flag, struct inode *inode)
635
-{
636
-	return test_bit(flag, &OVL_I(inode)->flags);
637661 }
638662 
639663 /**
....@@ -718,7 +742,7 @@
718742 
719743 	inode = d_inode(upperdentry);
720744 	if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) {
721
-		pr_warn_ratelimited("overlayfs: cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
745
+		pr_warn_ratelimited("cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
722746 				    upperdentry, inode->i_ino, inode->i_nlink);
723747 		/*
724748 		 * We either have a bug with persistent union nlink or a lower
....@@ -741,7 +765,8 @@
741765 		index = NULL;
742766 	} else if (ovl_index_all(dentry->d_sb)) {
743767 		/* Whiteout orphan index to block future open by handle */
744
-		err = ovl_cleanup_and_whiteout(indexdir, dir, index);
768
+		err = ovl_cleanup_and_whiteout(OVL_FS(dentry->d_sb),
769
+					       dir, index);
745770 	} else {
746771 		/* Cleanup orphan index entries */
747772 		err = ovl_cleanup(dir, index);
....@@ -757,7 +782,7 @@
757782 	return;
758783 
759784 fail:
760
-	pr_err("overlayfs: cleanup index of '%pd2' failed (%i)\n", dentry, err);
785
+	pr_err("cleanup index of '%pd2' failed (%i)\n", dentry, err);
761786 	goto out;
762787 }
763788 
....@@ -765,14 +790,14 @@
765790  * Operations that change overlay inode and upper inode nlink need to be
766791  * synchronized with copy up for persistent nlink accounting.
767792  */
768
-int ovl_nlink_start(struct dentry *dentry, bool *locked)
793
+int ovl_nlink_start(struct dentry *dentry)
769794 {
770
-	struct ovl_inode *oi = OVL_I(d_inode(dentry));
795
+	struct inode *inode = d_inode(dentry);
771796 	const struct cred *old_cred;
772797 	int err;
773798 
774
-	if (!d_inode(dentry))
775
-		return 0;
799
+	if (WARN_ON(!inode))
800
+		return -ENOENT;
776801 
777802 	/*
778803 	 * With inodes index is enabled, we store the union overlay nlink
....@@ -794,11 +819,11 @@
794819 			return err;
795820 	}
796821 
797
-	err = mutex_lock_interruptible(&oi->lock);
822
+	err = ovl_inode_lock_interruptible(inode);
798823 	if (err)
799824 		return err;
800825 
801
-	if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, d_inode(dentry)))
826
+	if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
802827 		goto out;
803828 
804829 	old_cred = ovl_override_creds(dentry->d_sb);
....@@ -809,31 +834,28 @@
809834 	 * value relative to the upper inode nlink in an upper inode xattr.
810835 	 */
811836 	err = ovl_set_nlink_upper(dentry);
812
-	ovl_revert_creds(old_cred);
837
+	ovl_revert_creds(dentry->d_sb, old_cred);
813838 
814839 out:
815840 	if (err)
816
-		mutex_unlock(&oi->lock);
817
-	else
818
-		*locked = true;
841
+		ovl_inode_unlock(inode);
819842 
820843 	return err;
821844 }
822845 
823
-void ovl_nlink_end(struct dentry *dentry, bool locked)
846
+void ovl_nlink_end(struct dentry *dentry)
824847 {
825
-	if (locked) {
826
-		if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) &&
827
-		    d_inode(dentry)->i_nlink == 0) {
828
-			const struct cred *old_cred;
848
+	struct inode *inode = d_inode(dentry);
829849 
830
-			old_cred = ovl_override_creds(dentry->d_sb);
831
-			ovl_cleanup_index(dentry);
832
-			ovl_revert_creds(old_cred);
833
-		}
850
+	if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) {
851
+		const struct cred *old_cred;
834852 
835
-		mutex_unlock(&OVL_I(d_inode(dentry))->lock);
853
+		old_cred = ovl_override_creds(dentry->d_sb);
854
+		ovl_cleanup_index(dentry);
855
+		ovl_revert_creds(dentry->d_sb, old_cred);
836856 	}
857
+
858
+	ovl_inode_unlock(inode);
837859 }
838860 
839861 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
....@@ -851,12 +873,12 @@
851873 err_unlock:
852874 	unlock_rename(workdir, upperdir);
853875 err:
854
-	pr_err("overlayfs: failed to lock workdir+upperdir\n");
876
+	pr_err("failed to lock workdir+upperdir\n");
855877 	return -EIO;
856878 }
857879 
858880 /* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
859
-int ovl_check_metacopy_xattr(struct dentry *dentry)
881
+int ovl_check_metacopy_xattr(struct ovl_fs *ofs, struct dentry *dentry)
860882 {
861883 	ssize_t res;
862884 
....@@ -864,7 +886,7 @@
864886 	if (!S_ISREG(d_inode(dentry)->i_mode))
865887 		return 0;
866888 
867
-	res = ovl_vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0);
889
+	res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_METACOPY, NULL, 0);
868890 	if (res < 0) {
869891 		if (res == -ENODATA || res == -EOPNOTSUPP)
870892 			return 0;
....@@ -873,7 +895,7 @@
873895 
874896 	return 1;
875897 out:
876
-	pr_warn_ratelimited("overlayfs: failed to get metacopy (%zi)\n", res);
898
+	pr_warn_ratelimited("failed to get metacopy (%zi)\n", res);
877899 	return res;
878900 }
879901 
....@@ -893,49 +915,27 @@
893915 	return (oe->numlower > 1);
894916 }
895917 
896
-ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value,
897
-		     size_t padding)
898
-{
899
-	ssize_t res;
900
-	char *buf = NULL;
901
-
902
-	res = ovl_vfs_getxattr(dentry, name, NULL, 0);
903
-	if (res < 0) {
904
-		if (res == -ENODATA || res == -EOPNOTSUPP)
905
-			return -ENODATA;
906
-		goto fail;
907
-	}
908
-
909
-	if (res != 0) {
910
-		buf = kzalloc(res + padding, GFP_KERNEL);
911
-		if (!buf)
912
-			return -ENOMEM;
913
-
914
-		res = ovl_vfs_getxattr(dentry, name, buf, res);
915
-		if (res < 0)
916
-			goto fail;
917
-	}
918
-	*value = buf;
919
-
920
-	return res;
921
-
922
-fail:
923
-	pr_warn_ratelimited("overlayfs: failed to get xattr %s: err=%zi)\n",
924
-			    name, res);
925
-	kfree(buf);
926
-	return res;
927
-}
928
-
929
-char *ovl_get_redirect_xattr(struct dentry *dentry, int padding)
918
+char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct dentry *dentry,
919
+			     int padding)
930920 {
931921 	int res;
932922 	char *s, *next, *buf = NULL;
933923 
934
-	res = ovl_getxattr(dentry, OVL_XATTR_REDIRECT, &buf, padding + 1);
935
-	if (res == -ENODATA)
924
+	res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_REDIRECT, NULL, 0);
925
+	if (res == -ENODATA || res == -EOPNOTSUPP)
936926 		return NULL;
937927 	if (res < 0)
938
-		return ERR_PTR(res);
928
+		goto fail;
929
+	if (res == 0)
930
+		goto invalid;
931
+
932
+	buf = kzalloc(res + padding + 1, GFP_KERNEL);
933
+	if (!buf)
934
+		return ERR_PTR(-ENOMEM);
935
+
936
+	res = ovl_do_getxattr(ofs, dentry, OVL_XATTR_REDIRECT, buf, res);
937
+	if (res < 0)
938
+		goto fail;
939939 	if (res == 0)
940940 		goto invalid;
941941 
....@@ -952,8 +952,39 @@
952952 
953953 	return buf;
954954 invalid:
955
-	pr_warn_ratelimited("overlayfs: invalid redirect (%s)\n", buf);
955
+	pr_warn_ratelimited("invalid redirect (%s)\n", buf);
956956 	res = -EINVAL;
957
+	goto err_free;
958
+fail:
959
+	pr_warn_ratelimited("failed to get redirect (%i)\n", res);
960
+err_free:
957961 	kfree(buf);
958962 	return ERR_PTR(res);
959963 }
964
+
965
+/*
966
+ * ovl_sync_status() - Check fs sync status for volatile mounts
967
+ *
968
+ * Returns 1 if this is not a volatile mount and a real sync is required.
969
+ *
970
+ * Returns 0 if syncing can be skipped because mount is volatile, and no errors
971
+ * have occurred on the upperdir since the mount.
972
+ *
973
+ * Returns -errno if it is a volatile mount, and the error that occurred since
974
+ * the last mount. If the error code changes, it'll return the latest error
975
+ * code.
976
+ */
977
+
978
+int ovl_sync_status(struct ovl_fs *ofs)
979
+{
980
+	struct vfsmount *mnt;
981
+
982
+	if (ovl_should_sync(ofs))
983
+		return 1;
984
+
985
+	mnt = ovl_upper_mnt(ofs);
986
+	if (!mnt)
987
+		return 0;
988
+
989
+	return errseq_check(&mnt->mnt_sb->s_wb_err, ofs->errseq);
990
+}