From 7b3a871ed995270268a481404454ceafe1a87478 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Sat, 28 Jun 2008 08:32:09 +1000 Subject: [PATCH] md: handle operation chaining in raid5_run_ops From: Dan Williams Neil said: > At the end of ops_run_compute5 you have: > /* ack now if postxor is not set to be run */ > if (tx && !test_bit(STRIPE_OP_POSTXOR, &s->ops_run)) > async_tx_ack(tx); > > It looks odd having that test there. Would it fit in raid5_run_ops > better? The intended global interpretation is that raid5_run_ops can build a chain of xor and memcpy operations. When MD registers the compute-xor it tells async_tx to keep the operation handle around so that another item in the dependency chain can be submitted. If we are just computing a block to satisfy a read then we can terminate the chain immediately. raid5_run_ops gives a better context for this test since it cares about the entire chain. Signed-off-by: Dan Williams Signed-off-by: Neil Brown --- drivers/md/raid5.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index c71246061c0e..456c3c2c961d 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -574,8 +574,7 @@ static void ops_complete_compute5(void *stripe_head_ref) release_stripe(sh); } -static struct dma_async_tx_descriptor * -ops_run_compute5(struct stripe_head *sh, unsigned long ops_request) +static struct dma_async_tx_descriptor *ops_run_compute5(struct stripe_head *sh) { /* kernel stack size limits the total number of disks */ int disks = sh->disks; @@ -605,10 +604,6 @@ ops_run_compute5(struct stripe_head *sh, unsigned long ops_request) ASYNC_TX_XOR_ZERO_DST, NULL, ops_complete_compute5, sh); - /* ack now if postxor is not set to be run */ - if (tx && !test_bit(STRIPE_OP_POSTXOR, &ops_request)) - async_tx_ack(tx); - return tx; } @@ -813,8 +808,12 @@ static void raid5_run_ops(struct stripe_head *sh, unsigned long ops_request) overlap_clear++; } - if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) - tx = ops_run_compute5(sh, ops_request); + if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) { + tx = ops_run_compute5(sh); + /* terminate the chain if postxor is not set to be run */ + if (tx && !test_bit(STRIPE_OP_POSTXOR, &ops_request)) + async_tx_ack(tx); + } if (test_bit(STRIPE_OP_PREXOR, &ops_request)) tx = ops_run_prexor(sh, tx); -- 2.20.1