>From 7a3031f86cfc70e1c102045c410640645c298b8c Mon Sep 17 00:00:00 2001
From: Bian Yu <bianyu@xxxxxxxxxxx>
Date: Fri, 23 Aug 2013 10:43:28 -0400
Subject: [PATCH] When hit a read error, retry request with R5_ReadNoMerge flag.
Because of block layer merge, one bio fails will cause other bios
which belongs to the same request fails, so raid5_end_read_request
will record all these bios as badblocks.
If retry request with R5_ReadNoMerge flag to avoid bios merge,
badblocks can only record sector which is bad exactly.
test:
hdparm --yes-i-know-what-i-am-doing --make-bad-sector 300000 /dev/sdb
mdadm -C /dev/md0 -l5 -n3 /dev/sd[bcd] --assume-clean
mdadm /dev/md0 -f /dev/sdd
mdadm /dev/md0 -r /dev/sdd
mdadm --zero-superblock /dev/sdd
mdadm /dev/md0 -a /dev/sdd
1. Without this patch:
cat /sys/block/md0/md/rd*/bad_blocks
299776 256
299776 256
2. With this patch:
cat /sys/block/md0/md/rd*/bad_blocks
300000 8
300000 8
Signed-off-by: Bian Yu <bianyu@xxxxxxxxxxx>
---
drivers/md/raid5.c | 26 +++++++++++++-------------
1 files changed, 13 insertions(+), 13 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 840d0dd..796ad52 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1875,21 +1875,21 @@ static void raid5_end_read_request(struct bio
* bi, int error)
mdname(conf->mddev), bdn);
else
retry = 1;
- if (retry)
- if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
+ if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
+ if (retry) {
set_bit(R5_ReadError, &sh->dev[i].flags);
clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
- } else
- set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
- else {
- clear_bit(R5_ReadError, &sh->dev[i].flags);
- clear_bit(R5_ReWrite, &sh->dev[i].flags);
- if (!(set_bad
- && test_bit(In_sync, &rdev->flags)
- && rdev_set_badblocks(
- rdev, sh->sector, STRIPE_SECTORS, 0)))
- md_error(conf->mddev, rdev);
- }
+ } else {
+ clear_bit(R5_ReadError, &sh->dev[i].flags);
+ clear_bit(R5_ReWrite, &sh->dev[i].flags);
+ if (!(set_bad
+ && test_bit(In_sync, &rdev->flags)
+ && rdev_set_badblocks(rdev,
+ sh->sector, STRIPE_SECTORS, 0)))
+ md_error(conf->mddev, rdev);
+ }
+ } else
+ set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
}
rdev_dec_pending(rdev, conf->mddev);
clear_bit(R5_LOCKED, &sh->dev[i].flags);
--
1.7.1
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