switch fat to ->s_d_op, close exportfs races there

don't bother with lock_super() in fat_fill_super() callers, while
we are at it - there won't be any concurrency anyway.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 9 insertions, 18 deletions

diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
index 35ffe43..7114990 100644
--- a/fs/fat/namei_msdos.c
+++ b/fs/fat/namei_msdos.c
@@ -227,11 +227,7 @@ static struct dentry *msdos_lookup(struct inode *dir, struct dentry *dentry,
 	}
 out:
 	unlock_super(sb);
-	d_set_d_op(dentry, &msdos_dentry_operations);
-	dentry = d_splice_alias(inode, dentry);
-	if (dentry)
-		d_set_d_op(dentry, &msdos_dentry_operations);
-	return dentry;
+	return d_splice_alias(inode, dentry);
 
 error:
 	unlock_super(sb);
@@ -661,21 +657,16 @@ static const struct inode_operations msdos_dir_inode_operations = {
 	.getattr	= fat_getattr,
 };
 
-static int msdos_fill_super(struct super_block *sb, void *data, int silent)
+static void setup(struct super_block *sb)
 {
-	int res;
-
-	lock_super(sb);
-	res = fat_fill_super(sb, data, silent, &msdos_dir_inode_operations, 0);
-	if (res) {
-		unlock_super(sb);
-		return res;
-	}
-
+	sb->s_d_op = &msdos_dentry_operations;
 	sb->s_flags |= MS_NOATIME;
-	d_set_d_op(sb->s_root, &msdos_dentry_operations);
-	unlock_super(sb);
-	return 0;
+}
+
+static int msdos_fill_super(struct super_block *sb, void *data, int silent)
+{
+	return fat_fill_super(sb, data, silent, &msdos_dir_inode_operations,
+			     0, setup);
 }
 
 static struct dentry *msdos_mount(struct file_system_type *fs_type,