staging: erofs: no need to take page lock in readdir

VFS will take inode_lock for readdir, therefore no need to
take page lock in readdir at all just as the majority of
other generic filesystems.
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/erofs/dir.c

@@ -98,7 +98,6 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 		if (IS_ERR(dentry_page))
 			continue;
 
-		lock_page(dentry_page);
 		de = (struct erofs_dirent *)kmap(dentry_page);
 
 		nameoff = le16_to_cpu(de->nameoff);
@@ -128,7 +127,6 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 skip_this:
 		kunmap(dentry_page);
 
-		unlock_page(dentry_page);
 		put_page(dentry_page);
 
 		ctx->pos = blknr_to_addr(i) + ofs;