[dm-devel] [PATCH 1/2] blkdev: fix merge_bvec_fn return value checks
Neil Brown
neilb at suse.de
Mon Mar 8 05:43:36 UTC 2010
On Fri, 5 Mar 2010 17:37:16 +0000
Alasdair G Kergon <agk at redhat.com> wrote:
> On Thu, Mar 04, 2010 at 06:59:21PM +0100, Lars Ellenberg wrote:
> > + /* Restricting max_sectors is not enough.
> > + * If someone uses bio_add_page to add 8 disjunct 512 byte
> > + * partial pages to a bio, it would succeed,
> > + * but could still cross a border of whatever restrictions
> > + * are below us (raid0 stripe boundary). An attempted
> > + * bio_split would not succeed, because bi_vcnt is 8.
> > + * E.g. the xen io layer is known to trigger this.
> > + */
>
> Sounds plausible.
>
> Do you or anyone readingt his have example messages demonstrating the failure
> when this patch is not applied?
Yes. This
http://marc.info/?l=linux-raid&m=126672681521073&w=2
almost certainly refers to that problem.
NeilBrown
>
> Alasdair.
>
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