Partial parity is calculated as follows:
- reconstruct-write case:
xor data from all not updated disks in a stripe
- read-modify-write case:
xor old data and parity from all updated disks in a stripe
Implement it using the async_tx API and integrate into raid_run_ops().
It must be called when we still have access to old data, so do it when
STRIPE_OP_BIODRAIN is set, but before ops_run_prexor5(). The result is
stored into sh->ppl_page.
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx>
---
drivers/md/raid5.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 75 insertions(+)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 77a503d3..2169de5 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1941,6 +1941,49 @@ static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu
&sh->ops.zero_sum_result, percpu->spare_page, &submit);
}
+static struct dma_async_tx_descriptor *
+ops_run_partial_parity(struct stripe_head *sh, struct raid5_percpu *percpu,
+ struct dma_async_tx_descriptor *tx)
+{
+ int disks = sh->disks;
+ struct page **xor_srcs = flex_array_get(percpu->scribble, 0);
+ int count = 0, pd_idx = sh->pd_idx, i;
+ struct async_submit_ctl submit;
+
+ if (test_bit(STRIPE_FULL_WRITE, &sh->state))
+ return tx;
+
+ if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
+ for (i = disks; i--;) {
+ struct r5dev *dev = &sh->dev[i];
+ if (test_bit(R5_Wantdrain, &dev->flags)
+ || i == pd_idx)
+ xor_srcs[count++] = dev->page;
+ }
+ } else if (sh->reconstruct_state == reconstruct_state_drain_run) {
+ for (i = disks; i--;) {
+ struct r5dev *dev = &sh->dev[i];
+ if (test_bit(R5_UPTODATE, &dev->flags))
+ xor_srcs[count++] = dev->page;
+ }
+ } else {
+ return tx;
+ }
+
+ init_async_submit(&submit, ASYNC_TX_XOR_ZERO_DST, tx,
+ NULL, sh, flex_array_get(percpu->scribble, 0)
+ + sizeof(struct page *) * (sh->disks + 2));
+
+ if (count == 1)
+ tx = async_memcpy(sh->ppl_page, xor_srcs[0], 0, 0, PAGE_SIZE,
+ &submit);
+ else
+ tx = async_xor(sh->ppl_page, xor_srcs, 0, count, PAGE_SIZE,
+ &submit);
+
+ return tx;
+}
+
static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
{
int overlap_clear = 0, i, disks = sh->disks;
@@ -1971,6 +2014,11 @@ static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
async_tx_ack(tx);
}
+ if (test_bit(STRIPE_OP_BIODRAIN, &ops_request) &&
+ test_bit(MD_HAS_PPL, &conf->mddev->flags) &&
+ conf->disks[sh->pd_idx].rdev)
+ tx = ops_run_partial_parity(sh, percpu, tx);
+
if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
if (level < 6)
tx = ops_run_prexor5(sh, percpu, tx);
@@ -3042,6 +3090,33 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
goto overlap;
+ /*
+ * PPL does not allow writes to different disks in the same stripe when
+ * they are not next to each other. Not really an overlap, but
+ * wait_for_overlap can be used to handle this.
+ */
+ if (forwrite && test_bit(MD_HAS_PPL, &conf->mddev->flags)) {
+ int i;
+ int di = 0;
+ int first = -1, last = -1;
+ int count = 0;
+ for (i = 0; i < sh->disks; i++) {
+ if (i == sh->pd_idx)
+ continue;
+
+ if (sh->dev[i].towrite || i == dd_idx) {
+ count++;
+ if (first < 0)
+ first = di;
+ last = di;
+ }
+ di++;
+ }
+
+ if (last > first && (last - first > count - 1))
+ goto overlap;
+ }
+
if (!forwrite || previous)
clear_bit(STRIPE_BATCH_READY, &sh->state);
--
2.10.1
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