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| author | Dan Williams <dan.j.williams@intel.com> | 2008-06-28 08:32:09 +1000 |
|---|---|---|
| committer | Neil Brown <neilb@notabene.brown> | 2008-06-28 08:32:09 +1000 |
| commit | 7b3a871ed995270268a481404454ceafe1a87478 (patch) | |
| tree | 1d86a84bd885f6c24213dd84b5406a38597b457e /drivers/md | |
| parent | d8ee0728b5b30d7a6f62c399a95e953616d31f23 (diff) | |
| download | linux-7b3a871ed995270268a481404454ceafe1a87478.tar.gz linux-7b3a871ed995270268a481404454ceafe1a87478.tar.bz2 linux-7b3a871ed995270268a481404454ceafe1a87478.zip | |
md: handle operation chaining in raid5_run_ops
From: Dan Williams <dan.j.williams@intel.com>
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 <dan.j.williams@intel.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid5.c | 15 |
1 files 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); |