On 7/25/07, Al Viro <[email protected]> wrote:
On Wed, Jul 25, 2007 at 11:48:35AM +0800, rae l wrote:
> Why alloc_super use a static variable default_op?
> the static struct super_operations default_op is just all zeros, and
> just referenced as the initial value of a new allocated super_block,
> what does it for?
So that we would not have to care about ->s_op *ever* being NULL.
But is it valuable? Compared to a waste of sizeof(struct super_block)
bytes memory.
When some code want to refer fs_type->s_op, it almost always want to
refer some function pointer in s_op with fs_type->s_op->***, but all
pointers in default_op are all NULLs, what about this scenario?
and if you do grep s_op in the source code, you will found nowhere
will want to test s_op or dependent on s_op not NULL.
So my opinion is to remove default_ops, just keep new allocated s_op NULL.
--
Denis Cheng
Linux Application Developer
"One of my most productive days was throwing away 1000 lines of code."
- Ken Thompson.
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