releases/4.11.2/md-raid1-avoid-reusing-a-resync-bio-after-error-handling.patch

   1 From 0c9d5b127f695818c2c5a3868c1f28ca2969e905 Mon Sep 17 00:00:00 2001
   2 From: NeilBrown <neilb@suse.com>
   3 Date: Thu, 6 Apr 2017 12:06:37 +1000
   4 Subject: md/raid1: avoid reusing a resync bio after error handling.
   5
   6 From: NeilBrown <neilb@suse.com>
   7
   8 commit 0c9d5b127f695818c2c5a3868c1f28ca2969e905 upstream.
   9
  10 fix_sync_read_error() modifies a bio on a newly faulty
  11 device by setting bi_end_io to end_sync_write.
  12 This ensure that put_buf() will still call rdev_dec_pending()
  13 as required, but makes sure that subsequent code in
  14 fix_sync_read_error() doesn't try to read from the device.
  15
  16 Unfortunately this interacts badly with sync_request_write()
  17 which assumes that any bio with bi_end_io set to non-NULL
  18 other than end_sync_read is safe to write to.
  19
  20 As the device is now faulty it doesn't make sense to write.
  21 As the bio was recently used for a read, it is "dirty"
  22 and not suitable for immediate submission.
  23 In particular, ->bi_next might be non-NULL, which will cause
  24 generic_make_request() to complain.
  25
  26 Break this interaction by refusing to write to devices
  27 which are marked as Faulty.
  28
  29 Reported-and-tested-by: Michael Wang <yun.wang@profitbricks.com>
  30 Fixes: 2e52d449bcec ("md/raid1: add failfast handling for reads.")
  31 Signed-off-by: NeilBrown <neilb@suse.com>
  32 Signed-off-by: Shaohua Li <shli@fb.com>
  33 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  34
  35 ---
  36  drivers/md/raid1.c |    2 ++
  37  1 file changed, 2 insertions(+)
  38
  39 --- a/drivers/md/raid1.c
  40 +++ b/drivers/md/raid1.c
  41 @@ -2222,6 +2222,8 @@ static void sync_request_write(struct md
  42                      (i == r1_bio->read_disk ||
  43                       !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
  44                         continue;
  45 +               if (test_bit(Faulty, &conf->mirrors[i].rdev->flags))
  46 +                       continue;
  47
  48                 bio_set_op_attrs(wbio, REQ_OP_WRITE, 0);
  49                 if (test_bit(FailFast, &conf->mirrors[i].rdev->flags))