4.4-stable review patch. If anyone has any objections, please let me know.
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From: NeilBrown neilb@suse.com
[ Upstream commit 235b6003fb28f0dd8e7ed8fbdb088bb548291766 ]
When reshaping a fully degraded raid5/raid6 to a larger nubmer of devices, the new device(s) are not in-sync and so that can make the newly grown stripe appear to be "failed". To avoid this, we set the R5_Expanded flag to say "Even though this device is not fully in-sync, this block is safe so don't treat the device as failed for this stripe". This flag is set for data devices, not not for parity devices.
Consequently, if you have a RAID6 with two devices that are partly recovered and a spare, and start a reshape to include the spare, then when the reshape gets past the point where the recovery was up to, it will think the stripes are failed and will get into an infinite loop, failing to make progress.
So when contructing parity on an EXPAND_READY stripe, set R5_Expanded.
Reported-by: Curt lightspd@gmail.com Signed-off-by: NeilBrown neilb@suse.com Signed-off-by: Shaohua Li shli@fb.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/raid5.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -1681,8 +1681,11 @@ static void ops_complete_reconstruct(voi struct r5dev *dev = &sh->dev[i];
if (dev->written || i == pd_idx || i == qd_idx) { - if (!discard && !test_bit(R5_SkipCopy, &dev->flags)) + if (!discard && !test_bit(R5_SkipCopy, &dev->flags)) { set_bit(R5_UPTODATE, &dev->flags); + if (test_bit(STRIPE_EXPAND_READY, &sh->state)) + set_bit(R5_Expanded, &dev->flags); + } if (fua) set_bit(R5_WantFUA, &dev->flags); if (sync)