On Mon, Feb 11, 2019 at 1:11 AM Jinpu Wang <jinpu.wang@xxxxxxxxxxxxxxx> wrote:
>
> >
> > sync_request_write no longer submits writes to a Faulty device. This has
> > the unfortunate side effect that bitmap bits can be incorrectly cleared
> > if a recovery is interrupted (previously, end_sync_write would have
> > prevented this). This means the next recovery may not copy everything
> > it should, potentially corrupting data.
> >
> > Add a function for doing the proper md_bitmap_end_sync, called from
> > end_sync_write and the Faulty case in sync_request_write.
> >
> > Fixes: 0c9d5b127f69 ("md/raid1: avoid reusing a resync bio after error
> > handling.")
> > Signed-off-by: Nate Dailey <nate.dailey@xxxxxxxxxxx>
Thanks Jinpu! I will take care of this patch and cc stable.
Would you like to add your Reviewed-by/Tested-by/Acked-by?
Song
> > ---
> > drivers/md/raid1.c | 28 ++++++++++++++++++----------
> > 1 file changed, 18 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> > index 1d54109071cc..fa47249fa3e4 100644
> > --- a/drivers/md/raid1.c
> > +++ b/drivers/md/raid1.c
> > @@ -1863,6 +1863,20 @@ static void end_sync_read(struct bio *bio)
> > reschedule_retry(r1_bio);
> > }
> >
> > +static void abort_sync_write(struct mddev *mddev, struct r1bio *r1_bio)
> > +{
> > + sector_t sync_blocks = 0;
> > + sector_t s = r1_bio->sector;
> > + long sectors_to_go = r1_bio->sectors;
> > +
> > + /* make sure these bits don't get cleared. */
> > + do {
> > + md_bitmap_end_sync(mddev->bitmap, s, &sync_blocks, 1);
> > + s += sync_blocks;
> > + sectors_to_go -= sync_blocks;
> > + } while (sectors_to_go > 0);
> > +}
> > +
> > static void end_sync_write(struct bio *bio)
> > {
> > int uptodate = !bio->bi_status;
> > @@ -1874,15 +1888,7 @@ static void end_sync_write(struct bio *bio)
> > struct md_rdev *rdev = conf->mirrors[find_bio_disk(r1_bio, bio)].rdev;
> >
> > if (!uptodate) {
> > - sector_t sync_blocks = 0;
> > - sector_t s = r1_bio->sector;
> > - long sectors_to_go = r1_bio->sectors;
> > - /* make sure these bits doesn't get cleared. */
> > - do {
> > - md_bitmap_end_sync(mddev->bitmap, s, &sync_blocks, 1);
> > - s += sync_blocks;
> > - sectors_to_go -= sync_blocks;
> > - } while (sectors_to_go > 0);
> > + abort_sync_write(mddev, r1_bio);
> > set_bit(WriteErrorSeen, &rdev->flags);
> > if (!test_and_set_bit(WantReplacement, &rdev->flags))
> > set_bit(MD_RECOVERY_NEEDED, &
> > @@ -2172,8 +2178,10 @@ static void sync_request_write(struct mddev
> > *mddev, struct r1bio *r1_bio)
> > (i == r1_bio->read_disk ||
> > !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
> > continue;
> > - if (test_bit(Faulty, &conf->mirrors[i].rdev->flags))
> > + if (test_bit(Faulty, &conf->mirrors[i].rdev->flags)) {
> > + abort_sync_write(mddev, r1_bio);
> > continue;
> > + }
> >
> > bio_set_op_attrs(wbio, REQ_OP_WRITE, 0);
> > if (test_bit(FailFast, &conf->mirrors[i].rdev->flags))
> > --
> > 2.19.1
>
> Thanks Nate, the patch looks good to me!
>
> Do you have a reproducer for the bug here? It would good to have a
> test case in blktest or mdadm test.
>
> As this could lead to data corruption, it should go to stable 4.14+, I
> guess Liu Song will mark it for stable :)
>
> Thanks.
>
> --
> Jack Wang
> Linux Kernel Developer
>
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