From: ChangSyun Peng <allenp...@synology.com>
commit a1c6ae3d9f3dd6aa5981a332a6f700cf1c25edef upstream.
In degraded raid5, we need to read parity to do reconstruct-write when
data disks fail. However, we can not read parity from
handle_stripe_dirtying() in force reconstruct-write mode.
Reproducible Steps:
1. Create degraded raid5
mdadm -C /dev/md2 --assume-clean -l5 -n3 /dev/sda2 /dev/sdb2 missing
2. Set rmw_level to 0
echo 0 > /sys/block/md2/md/rmw_level
3. IO to raid5
Now some io may be stuck in raid5. We can use handle_stripe_fill() to read
the parity in this situation.
Cc: <sta...@vger.kernel.org> # v4.4+
Reviewed-by: Alex Wu <ale...@synology.com>
Reviewed-by: BingJing Chang <bingji...@synology.com>
Reviewed-by: Danny Shih <dannys...@synology.com>
Signed-off-by: ChangSyun Peng <allenp...@synology.com>
Signed-off-by: Song Liu <songliubrav...@fb.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/md/raid5.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3596,6 +3596,7 @@ static int need_this_block(struct stripe
* is missing/faulty, then we need to read everything we can.
*/
if (sh->raid_conf->level != 6 &&
+ sh->raid_conf->rmw_level != PARITY_DISABLE_RMW &&
sh->sector < sh->raid_conf->mddev->recovery_cp)
/* reconstruct-write isn't being forced */
return 0;
@@ -4832,7 +4833,7 @@ static void handle_stripe(struct stripe_
* or to load a block that is being partially written.
*/
if (s.to_read || s.non_overwrite
- || (conf->level == 6 && s.to_write && s.failed)
+ || (s.to_write && s.failed)
|| (s.syncing && (s.uptodate + s.compute < disks))
|| s.replacing
|| s.expanding)
