From bd2ab67030e9116f1e4aae1289220255412b37fd Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 10 Apr 2008 21:29:27 -0700 Subject: md: close a livelock window in handle_parity_checks5 If a failure is detected after a parity check operation has been initiated, but before it completes handle_parity_checks5 will never quiesce operations on the stripe. Explicitly handle this case by "canceling" the parity check, i.e. clear the STRIPE_OP_CHECK flags and queue the stripe on the handle list again to refresh any non-uptodate blocks. Kernel versions >= 2.6.23 are susceptible. Cc: Cc: NeilBrown Signed-off-by: Dan Williams Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/raid5.c | 51 +++++++++++++++++++++++++++++---------------------- 1 file changed, 29 insertions(+), 22 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index c574cf5efb5..b162b839a66 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2348,25 +2348,15 @@ static void handle_issuing_new_write_requests6(raid5_conf_t *conf, static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh, struct stripe_head_state *s, int disks) { + int canceled_check = 0; + set_bit(STRIPE_HANDLE, &sh->state); - /* Take one of the following actions: - * 1/ start a check parity operation if (uptodate == disks) - * 2/ finish a check parity operation and act on the result - * 3/ skip to the writeback section if we previously - * initiated a recovery operation - */ - if (s->failed == 0 && - !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) { - if (!test_and_set_bit(STRIPE_OP_CHECK, &sh->ops.pending)) { - BUG_ON(s->uptodate != disks); - clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags); - sh->ops.count++; - s->uptodate--; - } else if ( - test_and_clear_bit(STRIPE_OP_CHECK, &sh->ops.complete)) { - clear_bit(STRIPE_OP_CHECK, &sh->ops.ack); - clear_bit(STRIPE_OP_CHECK, &sh->ops.pending); + /* complete a check operation */ + if (test_and_clear_bit(STRIPE_OP_CHECK, &sh->ops.complete)) { + clear_bit(STRIPE_OP_CHECK, &sh->ops.ack); + clear_bit(STRIPE_OP_CHECK, &sh->ops.pending); + if (s->failed == 0) { if (sh->ops.zero_sum_result == 0) /* parity is correct (on disc, * not in buffer any more) @@ -2391,7 +2381,8 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh, s->uptodate++; } } - } + } else + canceled_check = 1; /* STRIPE_INSYNC is not set */ } /* check if we can clear a parity disk reconstruct */ @@ -2404,12 +2395,28 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh, clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending); } + /* start a new check operation if there are no failures, the stripe is + * not insync, and a repair is not in flight + */ + if (s->failed == 0 && + !test_bit(STRIPE_INSYNC, &sh->state) && + !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) { + if (!test_and_set_bit(STRIPE_OP_CHECK, &sh->ops.pending)) { + BUG_ON(s->uptodate != disks); + clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags); + sh->ops.count++; + s->uptodate--; + } + } + /* Wait for check parity and compute block operations to complete - * before write-back + * before write-back. If a failure occurred while the check operation + * was in flight we need to cycle this stripe through handle_stripe + * since the parity block may not be uptodate */ - if (!test_bit(STRIPE_INSYNC, &sh->state) && - !test_bit(STRIPE_OP_CHECK, &sh->ops.pending) && - !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) { + if (!canceled_check && !test_bit(STRIPE_INSYNC, &sh->state) && + !test_bit(STRIPE_OP_CHECK, &sh->ops.pending) && + !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) { struct r5dev *dev; /* either failed parity check, or recovery is happening */ if (s->failed == 0) -- cgit