On 09/22/2016 11:52 AM, Paolo Bonzini wrote: > From: Eric Blake <[email protected]> > > When qemu uses iscsi devices in sg mode, iscsilun->block_size > is left at 0. Prior to commits cf081fca and similar, when > block limits were tracked in sectors, this did not matter: > various block limits were just left at 0. But when we started > scaling by block size, this caused SIGFPE. >
> +++ b/block/iscsi.c > @@ -1813,19 +1813,23 @@ static void iscsi_refresh_limits(BlockDriverState > *bs, Error **errp) > > IscsiLun *iscsilun = bs->opaque; > uint64_t max_xfer_len = iscsilun->use_16_for_rw ? 0xffffffff : 0xffff; > + unsigned int block_size = MIN_NON_ZERO(BDRV_SECTOR_SIZE, > + iscsilun->block_size); > > - bs->bl.request_alignment = iscsilun->block_size; > + assert(iscsilun->block_size >= BDRV_SECTOR_SIZE || bs->sg); > + > + bs->bl.request_alignment = block_size; Ouch. If iscsilun->block_size is 4k, this ends up changing bs->bl.request_alignment to 512, which is wrong. :( If I'm in time, let's drop this from the pull request, and I'll send a followup patch. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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