From ac4090d24c6a26211bc4523d920376e054d4f3f8 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 5 Aug 2008 15:54:13 +1000 Subject: [PATCH] Don't let a blocked_rdev interfere with read request in raid5/6 When we have externally managed metadata, we need to mark a failed device as 'Blocked' and not allow any writes until that device have been marked as faulty in the metadata and the Blocked flag has been removed. However it is perfectly OK to allow read requests when there is a Blocked device, and with a readonly array, there may not be any metadata-handler watching for blocked devices. So in raid5/raid6 only allow a Blocked device to interfere with Write request or resync. Read requests go through untouched. raid1 and raid10 already differentiate between read and write properly. Signed-off-by: NeilBrown --- drivers/md/raid5.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 17e0953c3c06..224de022e7c5 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2568,10 +2568,10 @@ static bool handle_stripe5(struct stripe_head *sh) if (dev->written) s.written++; rdev = rcu_dereference(conf->disks[i].rdev); - if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) { + if (blocked_rdev == NULL && + rdev && unlikely(test_bit(Blocked, &rdev->flags))) { blocked_rdev = rdev; atomic_inc(&rdev->nr_pending); - break; } if (!rdev || !test_bit(In_sync, &rdev->flags)) { /* The ReadError flag will just be confusing now */ @@ -2588,8 +2588,14 @@ static bool handle_stripe5(struct stripe_head *sh) rcu_read_unlock(); if (unlikely(blocked_rdev)) { - set_bit(STRIPE_HANDLE, &sh->state); - goto unlock; + if (s.syncing || s.expanding || s.expanded || + s.to_write || s.written) { + set_bit(STRIPE_HANDLE, &sh->state); + goto unlock; + } + /* There is nothing for the blocked_rdev to block */ + rdev_dec_pending(blocked_rdev, conf->mddev); + blocked_rdev = NULL; } if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) { @@ -2832,10 +2838,10 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page) if (dev->written) s.written++; rdev = rcu_dereference(conf->disks[i].rdev); - if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) { + if (blocked_rdev == NULL && + rdev && unlikely(test_bit(Blocked, &rdev->flags))) { blocked_rdev = rdev; atomic_inc(&rdev->nr_pending); - break; } if (!rdev || !test_bit(In_sync, &rdev->flags)) { /* The ReadError flag will just be confusing now */ @@ -2853,9 +2859,16 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page) rcu_read_unlock(); if (unlikely(blocked_rdev)) { - set_bit(STRIPE_HANDLE, &sh->state); - goto unlock; + if (s.syncing || s.expanding || s.expanded || + s.to_write || s.written) { + set_bit(STRIPE_HANDLE, &sh->state); + goto unlock; + } + /* There is nothing for the blocked_rdev to block */ + rdev_dec_pending(blocked_rdev, conf->mddev); + blocked_rdev = NULL; } + pr_debug("locked=%d uptodate=%d to_read=%d" " to_write=%d failed=%d failed_num=%d,%d\n", s.locked, s.uptodate, s.to_read, s.to_write, s.failed, -- 2.20.1