Re: [PATCH 04/22] block: Abstract out bvec iterator

Ed L Cashin
2013-08-13T19:19:01Z

On Tue, Aug 13, 2013 at 11:51:58AM -0700, Kent Overstreet wrote:
> On Tue, Aug 13, 2013 at 10:03:04AM -0400, Ed Cashin wrote:
> > On Aug 9, 2013, Ed Cashin wrote:
> > > On Aug 8, 2013, at 9:05 PM, Kent Overstreet wrote:
> > > ...
> > > > It's in the for-jens branch now.
> > >
> > >
> > > Just examining the patches, I like the way it cleans up the aoe code. I
> > > had a question about a new BUG added by the for-jens branch the
> > > read-response handling path of the aoe driver.
> >
> > The aoe driver in linux-bcache/for-jens commit 4c36c973a8f45 is
> > passing my tests.
> >
> > Here is a patch against that branch illustrating my suggestion for
> > handling bad target responses gracefully.
>
> Thanks - shall I just fold that into the aoe immutable bvec patch?

Yes, that would be good, thanks.

Unfortunately, the way I usually send patches to vger didn't work
this time. It looks like the MTA didn't retry after the
greylisting used SMTP temporary failures. So I'm trying a
different way to send and including the same patch for the
benefit of the Cc list.

commit 2c39f50b1ee02e2ac07fd072a883a91713da53cc
Author: Ed Cashin <ecashin@coraid.com>
Date: Tue Aug 13 10:50:28 2013 -0400

aoe: bad AoE responses fail I/O without BUG

Instead of having a BUG when the AoE target does something wrong,
just fail the I/O and log the problem with rate limiting.

diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index cacd48e..b9916a6 100644
--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -1096,7 +1096,6 @@ bvcpy(struct sk_buff *skb, struct bio *bio, struct bvec_iter iter, long cnt)
int soff = 0;
struct bio_vec bv;

- BUG_ON(cnt > iter.bi_size);
iter.bi_size = cnt;

__bio_for_each_segment(bv, bio, iter, iter) {
@@ -1196,6 +1195,14 @@ noskb: if (buf)
clear_bit(BIO_UPTODATE, &buf->bio->bi_flags);
break;
}
+ if (n > f->iter.bi_size) {
+ pr_err_ratelimited("%s e%ld.%d. bytes=%ld need=%u\n",
+ "aoe: too-large data size in read from",
+ (long) d->aoemajor, d->aoeminor,
+ n, f->iter.bi_size);
+ clear_bit(BIO_UPTODATE, &buf->bio->bi_flags);
+ break;
+ }
bvcpy(skb, f->buf->bio, f->iter, n);
case ATA_CMD_PIO_WRITE:
case ATA_CMD_PIO_WRITE_EXT:

--
Ed