From 976ea8d475675da6e86bd434328814ccbf5ae641 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Sat, 28 Jun 2008 08:32:03 +1000 Subject: [PATCH] md: replace STRIPE_OP_COMPUTE_BLK with STRIPE_COMPUTE_RUN From: Dan Williams Track the state of compute operations (recalculating a block from all the other blocks in a stripe) with a state flag. Reduces the scope of the STRIPE_OP_COMPUTE_BLK flag to only tracking whether a compute operation has been requested via the ops_request field of struct stripe_head_state. Note, the compute operation that is performed in the course of doing a 'repair' operation (check the parity block, recalculate it and write it back if the check result is not zero) is tracked separately with the 'check_state' variable. Compute operations are held off while a 'check' is in progress, and moving this check out to handle_issuing_new_read_requests5 the helper routine __handle_issuing_new_read_requests5 can be simplified. This is another step towards the removal of ops.{pending,ack,complete,count}, i.e. STRIPE_OP_COMPUTE_BLK only requests an operation and does not track the state of the operation. Signed-off-by: Dan Williams Signed-off-by: Neil Brown --- drivers/md/raid5.c | 65 +++++++++++++--------------------------------- 1 file changed, 18 insertions(+), 47 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index b9c0a32a4f95..835046bf384e 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -604,8 +604,6 @@ static void ops_complete_compute5(void *stripe_head_ref) clear_bit(STRIPE_COMPUTE_RUN, &sh->state); if (sh->check_state == check_state_compute_run) sh->check_state = check_state_compute_result; - else - set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete); set_bit(STRIPE_HANDLE, &sh->state); release_stripe(sh); } @@ -881,8 +879,7 @@ static void raid5_run_ops(struct stripe_head *sh, unsigned long pending, overlap_clear++; } - if (test_bit(STRIPE_OP_COMPUTE_BLK, &pending) || - test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) + if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) tx = ops_run_compute5(sh, pending); if (test_bit(STRIPE_OP_PREXOR, &pending)) @@ -1960,12 +1957,6 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh, struct r5dev *dev = &sh->dev[disk_idx]; struct r5dev *failed_dev = &sh->dev[s->failed_num]; - /* don't schedule compute operations or reads on the parity block while - * a check is in flight - */ - if (disk_idx == sh->pd_idx && sh->check_state) - return ~0; - /* is the data in this block needed, and can we get it? */ if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) && (dev->toread || @@ -1974,23 +1965,16 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh, (failed_dev->toread || (failed_dev->towrite && !test_bit(R5_OVERWRITE, &failed_dev->flags) ))))) { - /* 1/ We would like to get this block, possibly by computing it, - * but we might not be able to. - * - * 2/ Since parity check operations potentially make the parity - * block !uptodate it will need to be refreshed before any - * compute operations on data disks are scheduled. - * - * 3/ We hold off parity block re-reads until check operations - * have quiesced. + /* We would like to get this block, possibly by computing it, + * otherwise read it if the backing disk is insync */ - if ((s->uptodate == disks - 1) && !sh->check_state && + if ((s->uptodate == disks - 1) && (s->failed && disk_idx == s->failed_num)) { - set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending); + set_bit(STRIPE_COMPUTE_RUN, &sh->state); + set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request); set_bit(R5_Wantcompute, &dev->flags); sh->ops.target = disk_idx; s->req_compute = 1; - sh->ops.count++; /* Careful: from this point on 'uptodate' is in the eye * of raid5_run_ops which services 'compute' operations * before writes. R5_Wantcompute flags a block that will @@ -1999,12 +1983,7 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh, */ s->uptodate++; return 0; /* uptodate + compute == disks */ - } else if ((s->uptodate < disks - 1) && - test_bit(R5_Insync, &dev->flags)) { - /* Note: we hold off compute operations while checks are - * in flight, but we still prefer 'compute' over 'read' - * hence we only read if (uptodate < * disks-1) - */ + } else if (test_bit(R5_Insync, &dev->flags)) { set_bit(R5_LOCKED, &dev->flags); set_bit(R5_Wantread, &dev->flags); s->locked++; @@ -2021,20 +2000,13 @@ static void handle_issuing_new_read_requests5(struct stripe_head *sh, { int i; - /* Clear completed compute operations */ - if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete)) { - clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete); - clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.ack); - clear_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending); - } - /* look for blocks to read/compute, skip this if a compute * is already in flight, or if the stripe contents are in the * midst of changing due to a write */ - if (!test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) && - !test_bit(STRIPE_OP_PREXOR, &sh->ops.pending) && - !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) { + if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state && + !test_bit(STRIPE_OP_PREXOR, &sh->ops.pending) && + !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) { for (i = disks; i--; ) if (__handle_issuing_new_read_requests5( sh, s, i, disks) == 0) @@ -2236,10 +2208,9 @@ static void handle_issuing_new_write_requests5(raid5_conf_t *conf, * simultaneously. If this is not the case then new writes need to be * held off until the compute completes. */ - if ((s->req_compute || - !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) && - (s->locked == 0 && (rcw == 0 || rmw == 0) && - !test_bit(STRIPE_BIT_DELAY, &sh->state))) + if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) && + (s->locked == 0 && (rcw == 0 || rmw == 0) && + !test_bit(STRIPE_BIT_DELAY, &sh->state))) s->locked += handle_write_operations5(sh, rcw == 0, 0); } @@ -2410,6 +2381,7 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh, set_bit(STRIPE_INSYNC, &sh->state); else { sh->check_state = check_state_compute_run; + set_bit(STRIPE_COMPUTE_RUN, &sh->state); set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request); set_bit(R5_Wantcompute, &sh->dev[sh->pd_idx].flags); @@ -2725,8 +2697,7 @@ static void handle_stripe5(struct stripe_head *sh) * or to load a block that is being partially written. */ if (s.to_read || s.non_overwrite || - (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding || - test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) + (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding) handle_issuing_new_read_requests5(sh, &s, disks); /* Now we check to see if any write operations have recently @@ -2803,7 +2774,7 @@ static void handle_stripe5(struct stripe_head *sh) */ if (sh->check_state || (s.syncing && s.locked == 0 && - !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending) && + !test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !test_bit(STRIPE_INSYNC, &sh->state))) handle_parity_checks5(conf, sh, &s, disks); @@ -2869,7 +2840,7 @@ static void handle_stripe5(struct stripe_head *sh) } if (s.expanding && s.locked == 0 && - !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) + !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) handle_stripe_expansion(conf, sh, NULL); if (sh->ops.count) @@ -3089,7 +3060,7 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page) } if (s.expanding && s.locked == 0 && - !test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending)) + !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) handle_stripe_expansion(conf, sh, &r6s); unlock: