Re: How does the disk buffer cache work?

[Andrew Morton <akpm@digeo.com>]

Matthew Zahorik wrote:
> 
> On Mon, 30 Dec 2002, Andrew Morton wrote:
> 
> > > [.. the next function call in read_cache_page() is lock_page(), which we
> > > hang forever on ..]
> >
> > lock_page() will sleep until the page is unlocked.  The page is unlocked
> > from end_buffer_io_sync(), which is called from within the context of
> > the disk device driver's interrupt handler.
> 
> Okay, I'll track it down there.  Probably the driver not calling
> end_buffer_io_sync() when timed out.  When the bad drive is detached,
> things work fine - leading me to believe that hardware and interrupt
> routing wise things are okay.
> 

It won't call end_buffer_io_sync() explicitly - it calls the function which
is pointed at by the relevant buffer's b_end_io vector.  Typically that
will point at end_buffer_io_aysnc() or end_buffer_io_sync()