Re: [RFC][PATCH] ext3: don't read inode block if the buffer has a write error

Linus Torvalds
2008-06-24T03:02:36Z

On Mon, 23 Jun 2008, Andrew Morton wrote:
> > I don't know why it was done like this, or if anybody actually tested
> > any of it, but AFAIKS the best way to fix this is to simply not
> > clear any uptodate bits upon write errors.
>
> There's a plausible-sounding reason for this behaviour which I forgot
> about three years ago. Maybe Linus remembers?

We have to drop the data at _some_ point. Maybe some errors are transient,
but a whole lot aren't. Jank out your USB memory stick, and those writes
will continue fail. So you can't just keep things dirty - and that also
implies that the buffer sure as heck isn't up-to-date either.

Yes, we could haev a "retry once or twice", but quite frankly, that has
always been left to the low-level driver. By the time the buffer cache or
page cache sees the error, it should be considered more than "transient",
and the data in memory is simply not _useful_ any more.

So clearing the uptodate bit seems to be the logical thing to do. But on
the other hand, it's probably not helping much either, so I don't
personally care if we keep it "uptodate" - as long as the dirty bit
doesn't get set, and as long as there is *some* way to get rid of the bad
buffer later.

Linus