fatfs: switch write_lock to read_lock in fat_ioctl_get_attributes

There is no need to hold write_lock in fat_ioctl_get_attributes.
write_lock may make an impact on concurrency of fat_ioctl_get_attributes.
Signed-off-by: Yubo Feng <fengyubo3@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Link: http://lkml.kernel.org/r/1593308053-12702-1-git-send-email-fengyubo3@huawei.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/fat/file.c

@@ -25,9 +25,9 @@ static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
 {
 	u32 attr;
 
-	inode_lock(inode);
+	inode_lock_shared(inode);
 	attr = fat_make_attrs(inode);
-	inode_unlock(inode);
+	inode_unlock_shared(inode);
 
 	return put_user(attr, user_attr);
 }