Re: [PATCH] Prevent large file writeback starvation

[Andrew Morton <akpm@osdl.org>]

David Chinner <dgc@sgi.com> wrote:
>
> > So to fix both these problems we need to be smarter about terminating the
> > wb_kupdate() loop.  Something like "loop until no expired inodes have been
> > written".
> > 
> > Wildly untested patch:
> 
> Wildly untested assertion - it won't fix my case for the same reason I'm seeing
> the current code not working - we abort higher up in writeback_inodes()
> on the age check.

You mean that we're in the state

a) big-dirty-expired inode is on s_dirty

b) small-dirty-not-expired inode is on s_io

sync_sb_inodes() sees the small-dirty-not-expired inode on s_io and gives up?


In which case, yes, perhaps leaving big-dirty-expired inode on s_io is the
right thing to do.  But should we be checking that it has expired before
deciding to do this?  We don't want to get in a situation where continuous
overwriting of a large file causes other files on that fs to never be
written out.