Re: Stale super_blocks in 2.2

[Phil Auld <pauld@egenera.com>]

Alan Cox wrote:
> 
> > That can be a problem for fiber channel devices. I saw some issues with
> > invalidate_buffers and page caching discussed in 2.4 space. Any reasons
> > come to mind why I shouldn't call invalidate on the the way down instead
> > (or in addition)?
> 
> The I/O completed a few seconds later anyway when bdflush got around to
> writing the data back out. I dont plan to change 2.2. 2.4 doesnt do that
> optimisation which is annoying in a few cases and a lot less suprising in
> others

Sure, the I/O completes, but the buffer_head is still in memory, valid and
uptodate.
On a subsequent mount the super_block comes from memory not disk. This works
as long as nobody else mounted that file system in between. 

I can make the changes needed. I was really curious if you, or anyone else,
thought there might be page caching issues involved with invalidating on the way
down.

Thanks the time,

Phil


------------------------------------------------------
Philip R. Auld,Ph.D.                  Techinical Staff
Egenera Corp.                        pauld@egenera.com
165 Forest St, Marlboro, MA 01752        (508)786-9444