Re: [PATCH 4/5] writeback: remove pages_skipped accounting in __block_write_full_page()

Andrew Morton
2007-10-04T21:27:33Z

On Tue, 02 Oct 2007 16:41:47 +0800
Fengguang Wu <wfg@mail.ustc.edu.cn> wrote:

> This patch fixes this bug. Though I'm not sure why __block_write_full_page()
> is called only to do nothing and who actually issued the writeback for us.

kjourald wrote the page's buffers back (ext3 in ordered-data mode). The VM
didn't know about that, so we have a PageDirty page which has clean
buffers.

We rely upon the VFS writeback code to "discover" that this dirty page has
clean buffers: the VFS will attempt to write the dirty page and will end up
marking the page clean without performing any IO.