On Mon, 8 Jul 2013 16:25:14 -0400 Joe Lawrence <joe.lawrence@xxxxxxxxxxx> wrote: > bio_copy_data() cannot execute on a fully completed source (or > destination) bio. MD RAID1 is recycling a completed read bio for RAID > repair purposes and needs to fix up the source and destination bios for > bio_copy_data(): in particular, the io-vector index needs to be rewound > and the bios unchained. > > Suggested-by: NeilBrown <neilb@xxxxxxx> > Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx> Thanks Joe. Jens: are you happy with this? If so is it OK for me to forward to Linus and -stable for 3.10, or would you rather? The follow-on patch which uses the so avoid a crash is http://marc.info/?l=linux-raid&m=137331514131503&w=2 (This is sitting near the top of "git://neil.brown.name/md for-next" if you want to cherry-pick it). Thanks, NeilBrown > --- > drivers/md/raid1.c | 28 +++++----------------------- > 1 file changed, 5 insertions(+), 23 deletions(-) > > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c > index 6e17f81..bb1e80f 100644 > --- a/drivers/md/raid1.c > +++ b/drivers/md/raid1.c > @@ -1861,7 +1861,6 @@ static int process_checks(struct r1bio *r1_bio) > int j; > struct bio *pbio = r1_bio->bios[primary]; > struct bio *sbio = r1_bio->bios[i]; > - int size; > > if (sbio->bi_end_io != end_sync_read) > continue; > @@ -1887,28 +1886,11 @@ static int process_checks(struct r1bio *r1_bio) > rdev_dec_pending(conf->mirrors[i].rdev, mddev); > continue; > } > - /* fixup the bio for reuse */ > - bio_reset(sbio); > - sbio->bi_vcnt = vcnt; > - sbio->bi_size = r1_bio->sectors << 9; > - sbio->bi_sector = r1_bio->sector + > - conf->mirrors[i].rdev->data_offset; > - sbio->bi_bdev = conf->mirrors[i].rdev->bdev; > - sbio->bi_end_io = end_sync_read; > - sbio->bi_private = r1_bio; > - > - size = sbio->bi_size; > - for (j = 0; j < vcnt ; j++) { > - struct bio_vec *bi; > - bi = &sbio->bi_io_vec[j]; > - bi->bv_offset = 0; > - if (size > PAGE_SIZE) > - bi->bv_len = PAGE_SIZE; > - else > - bi->bv_len = size; > - size -= PAGE_SIZE; > - } > - > + /* copy pbio io_vec data into sbio, but first reset io_vec > + * index and unchain both */ > + bio_rewind(pbio); > + bio_rewind(sbio); > + pbio->bi_next = sbio->bi_next = NULL; > bio_copy_data(sbio, pbio); > } > return 0;
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