From: Yu Kuai Date: Fri, 23 Jan 2026 18:26:22 +0000 (+0800) Subject: md/raid5: fix IO hang with degraded array with llbitmap X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cd1635d844d26471c56c0a432abdee12fc9ad735;p=thirdparty%2Fkernel%2Flinux.git md/raid5: fix IO hang with degraded array with llbitmap When llbitmap bit state is still unwritten, any new write should force rcw, as bitmap_ops->blocks_synced() is checked in handle_stripe_dirtying(). However, later the same check is missing in need_this_block(), causing stripe to deadloop during handling because handle_stripe() will decide to go to handle_stripe_fill(), meanwhile need_this_block() always return 0 and nothing is handled. Link: https://lore.kernel.org/linux-raid/20260123182623.3718551-2-yukuai@fnnas.com Fixes: 5ab829f1971d ("md/md-llbitmap: introduce new lockless bitmap") Signed-off-by: Yu Kuai Reviewed-by: Li Nan --- diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 6d408aaaacf37..8854e024f3113 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3751,9 +3751,14 @@ static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s, struct r5dev *dev = &sh->dev[disk_idx]; struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]], &sh->dev[s->failed_num[1]] }; + struct mddev *mddev = sh->raid_conf->mddev; + bool force_rcw = false; int i; - bool force_rcw = (sh->raid_conf->rmw_level == PARITY_DISABLE_RMW); + if (sh->raid_conf->rmw_level == PARITY_DISABLE_RMW || + (mddev->bitmap_ops && mddev->bitmap_ops->blocks_synced && + !mddev->bitmap_ops->blocks_synced(mddev, sh->sector))) + force_rcw = true; if (test_bit(R5_LOCKED, &dev->flags) || test_bit(R5_UPTODATE, &dev->flags))