ovl: negate the ofs->share_whiteout boolean

The default common case is that whiteout sharing is enabled.
Change to storing the negated no_shared_whiteout state, so we will not
need to initialize it.

This is the first step towards removing all config and feature
initializations out of ovl_fill_super().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>

fs/overlayfs/dir.c

@@ -83,7 +83,7 @@ static struct dentry *ovl_whiteout(struct ovl_fs *ofs)
 		ofs->whiteout = whiteout;
 	}
 
-	if (ofs->share_whiteout) {
+	if (!ofs->no_shared_whiteout) {
 		whiteout = ovl_lookup_temp(ofs, workdir);
 		if (IS_ERR(whiteout))
 			goto out;
@@ -95,7 +95,7 @@ static struct dentry *ovl_whiteout(struct ovl_fs *ofs)
 		if (err != -EMLINK) {
 			pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n",
 				ofs->whiteout->d_inode->i_nlink, err);
-			ofs->share_whiteout = false;
+			ofs->no_shared_whiteout = true;
 		}
 		dput(whiteout);
 	}

fs/overlayfs/ovl_entry.h

@@ -86,7 +86,6 @@ struct ovl_fs {
 	/* Did we take the inuse lock? */
 	bool upperdir_locked;
 	bool workdir_locked;
-	bool share_whiteout;
 	/* Traps in ovl inode cache */
 	struct inode *workbasedir_trap;
 	struct inode *workdir_trap;
@@ -95,8 +94,9 @@ struct ovl_fs {
 	int xino_mode;
 	/* For allocation of non-persistent inode numbers */
 	atomic_long_t last_ino;
-	/* Whiteout dentry cache */
+	/* Shared whiteout cache */
 	struct dentry *whiteout;
+	bool no_shared_whiteout;
 	/* r/o snapshot of upperdir sb's only taken on volatile mounts */
 	errseq_t errseq;
 };

fs/overlayfs/super.c

@@ -1954,9 +1954,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 	if (!cred)
 		goto out_err;
 
-	/* Is there a reason anyone would want not to share whiteouts? */
-	ofs->share_whiteout = true;
-
 	ofs->config.index = ovl_index_def;
 	ofs->config.uuid = true;
 	ofs->config.nfs_export = ovl_nfs_export_def;