Re: [PATCH] btrfs: call mark_inode_dirty when i_size is updated

[Chris Mason <chris.mason@oracle.com>]

On Mon, 2009-02-02 at 20:00 +0900, Hisashi Hifumi wrote:
> Hi Chris.
> 
> I think it is needed to call mark_inode_dirty() when file size expands
> in order to flush metadata updates to HDD through sync() syscall or
> background_writeout().
> 

Thanks for reading through this code and sending the patch.

I find the I_DIRTY flags one of the more confusing parts of the generic
fs writeback cdoe.  But, I think what happens is the
btrfs_set_page_dirty function calls __set_page_dirty_nobuffers() which
does:

if (mapping->host) {
     /* !PageAnon && !swapper_space */
      __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
}

This should be enough to make sure the btrfs inodes are processed by
background writeout and sync().  Please let me know if I'm misreading
things.

-chris