--- /dev/null
+From 4f4fd7c5798bbdd5a03a60f6269cf1177fbd11ef Mon Sep 17 00:00:00 2001
+From: Nigel Croxon <ncroxon@redhat.com>
+Date: Fri, 29 Mar 2019 10:46:15 -0700
+Subject: Don't jump to compute_result state from check_result state
+
+From: Nigel Croxon <ncroxon@redhat.com>
+
+commit 4f4fd7c5798bbdd5a03a60f6269cf1177fbd11ef upstream.
+
+Changing state from check_state_check_result to
+check_state_compute_result not only is unsafe but also doesn't
+appear to serve a valid purpose. A raid6 check should only be
+pushing out extra writes if doing repair and a mis-match occurs.
+The stripe dev management will already try and do repair writes
+for failing sectors.
+
+This patch makes the raid6 check_state_check_result handling
+work more like raid5's. If somehow too many failures for a
+check, just quit the check operation for the stripe. When any
+checks pass, don't try and use check_state_compute_result for
+a purpose it isn't needed for and is unsafe for. Just mark the
+stripe as in sync for passing its parity checks and let the
+stripe dev read/write code and the bad blocks list do their
+job handling I/O errors.
+
+Repro steps from Xiao:
+
+These are the steps to reproduce this problem:
+1. redefined OPT_MEDIUM_ERR_ADDR to 12000 in scsi_debug.c
+2. insmod scsi_debug.ko dev_size_mb=11000 max_luns=1 num_tgts=1
+3. mdadm --create /dev/md127 --level=6 --raid-devices=5 /dev/sde1 /dev/sde2 /dev/sde3 /dev/sde5 /dev/sde6
+sde is the disk created by scsi_debug
+4. echo "2" >/sys/module/scsi_debug/parameters/opts
+5. raid-check
+
+It panic:
+[ 4854.730899] md: data-check of RAID array md127
+[ 4854.857455] sd 5:0:0:0: [sdr] tag#80 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
+[ 4854.859246] sd 5:0:0:0: [sdr] tag#80 Sense Key : Medium Error [current]
+[ 4854.860694] sd 5:0:0:0: [sdr] tag#80 Add. Sense: Unrecovered read error
+[ 4854.862207] sd 5:0:0:0: [sdr] tag#80 CDB: Read(10) 28 00 00 00 2d 88 00 04 00 00
+[ 4854.864196] print_req_error: critical medium error, dev sdr, sector 11656 flags 0
+[ 4854.867409] sd 5:0:0:0: [sdr] tag#100 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
+[ 4854.869469] sd 5:0:0:0: [sdr] tag#100 Sense Key : Medium Error [current]
+[ 4854.871206] sd 5:0:0:0: [sdr] tag#100 Add. Sense: Unrecovered read error
+[ 4854.872858] sd 5:0:0:0: [sdr] tag#100 CDB: Read(10) 28 00 00 00 2e e0 00 00 08 00
+[ 4854.874587] print_req_error: critical medium error, dev sdr, sector 12000 flags 4000
+[ 4854.876456] sd 5:0:0:0: [sdr] tag#101 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
+[ 4854.878552] sd 5:0:0:0: [sdr] tag#101 Sense Key : Medium Error [current]
+[ 4854.880278] sd 5:0:0:0: [sdr] tag#101 Add. Sense: Unrecovered read error
+[ 4854.881846] sd 5:0:0:0: [sdr] tag#101 CDB: Read(10) 28 00 00 00 2e e8 00 00 08 00
+[ 4854.883691] print_req_error: critical medium error, dev sdr, sector 12008 flags 4000
+[ 4854.893927] sd 5:0:0:0: [sdr] tag#166 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
+[ 4854.896002] sd 5:0:0:0: [sdr] tag#166 Sense Key : Medium Error [current]
+[ 4854.897561] sd 5:0:0:0: [sdr] tag#166 Add. Sense: Unrecovered read error
+[ 4854.899110] sd 5:0:0:0: [sdr] tag#166 CDB: Read(10) 28 00 00 00 2e e0 00 00 10 00
+[ 4854.900989] print_req_error: critical medium error, dev sdr, sector 12000 flags 0
+[ 4854.902757] md/raid:md127: read error NOT corrected!! (sector 9952 on sdr1).
+[ 4854.904375] md/raid:md127: read error NOT corrected!! (sector 9960 on sdr1).
+[ 4854.906201] ------------[ cut here ]------------
+[ 4854.907341] kernel BUG at drivers/md/raid5.c:4190!
+
+raid5.c:4190 above is this BUG_ON:
+
+ handle_parity_checks6()
+ ...
+ BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
+
+Cc: <stable@vger.kernel.org> # v3.16+
+OriginalAuthor: David Jeffery <djeffery@redhat.com>
+Cc: Xiao Ni <xni@redhat.com>
+Tested-by: David Jeffery <djeffery@redhat.com>
+Signed-off-by: David Jeffy <djeffery@redhat.com>
+Signed-off-by: Nigel Croxon <ncroxon@redhat.com>
+Signed-off-by: Song Liu <songliubraving@fb.com>
+Signed-off-by: Jens Axboe <axboe@kernel.dk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/md/raid5.c | 19 ++++---------------
+ 1 file changed, 4 insertions(+), 15 deletions(-)
+
+--- a/drivers/md/raid5.c
++++ b/drivers/md/raid5.c
+@@ -3414,26 +3414,15 @@ static void handle_parity_checks6(struct
+ case check_state_check_result:
+ sh->check_state = check_state_idle;
+
++ if (s->failed > 1)
++ break;
+ /* handle a successful check operation, if parity is correct
+ * we are done. Otherwise update the mismatch count and repair
+ * parity if !MD_RECOVERY_CHECK
+ */
+ if (sh->ops.zero_sum_result == 0) {
+- /* both parities are correct */
+- if (!s->failed)
+- set_bit(STRIPE_INSYNC, &sh->state);
+- else {
+- /* in contrast to the raid5 case we can validate
+- * parity, but still have a failure to write
+- * back
+- */
+- sh->check_state = check_state_compute_result;
+- /* Returning at this point means that we may go
+- * off and bring p and/or q uptodate again so
+- * we make sure to check zero_sum_result again
+- * to verify if p or q need writeback
+- */
+- }
++ /* Any parity checked was correct */
++ set_bit(STRIPE_INSYNC, &sh->state);
+ } else {
+ atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
+ if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
projects / thirdparty / kernel / stable-queue.git / commitdiff
