Scheduling and processing the asynchronous computations.
handle_stripe will compute a block when a backing disk has failed. Since both
RAID-5/6 use the same ops_complete_compute() we should set the second
computation target in RAID-5 to (-1) [no target].
Signed-off-by: Yuri Tikhonov <yur@xxxxxxxxxxx>
Signed-off-by: Mikhail Cherkashin <mike@xxxxxxxxxxx>
--
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 3e8f896..f0f8d7f 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2770,6 +2770,7 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
set_bit(R5_Wantcompute, &dev->flags);
sh->ops.target = disk_idx;
+ sh->ops.target2 = -1; /* no second target */
s->req_compute = 1;
sh->ops.count++;
/* Careful: from this point on 'uptodate' is in the eye
@@ -2830,63 +2831,138 @@ static void handle_issuing_new_read_requests5(struct stripe_head *sh,
set_bit(STRIPE_HANDLE, &sh->state);
}
-static void handle_issuing_new_read_requests6(struct stripe_head *sh,
+/* __handle_issuing_new_read_requests6 - returns 0 if there are no more disks
+ * to process
+ */
+static int __handle_issuing_new_read_requests6(struct stripe_head *sh,
struct stripe_head_state *s, struct r6_state *r6s,
- int disks)
+ int disk_idx, int disks)
{
- int i;
struct stripe_queue *sq = sh->sq;
+ struct r5dev *dev = &sh->dev[disk_idx];
+ struct r5_queue_dev *dev_q = &sq->dev[disk_idx];
+ struct r5dev *failed_dev[2] = { &sh->dev[r6s->failed_num[0]],
+ &sh->dev[r6s->failed_num[1]]};
+ struct r5_queue_dev *failed_dev_q[2] = { &sq->dev[r6s->failed_num[0]],
+ &sq->dev[r6s->failed_num[1]]};
- for (i = disks; i--; ) {
- struct r5dev *dev = &sh->dev[i];
- struct r5_queue_dev *dev_q = &sq->dev[i];
+ /* don't schedule compute operations or reads on
+ * the parity blocks while a check is in flight
+ */
+ if ((disk_idx == sq->pd_idx || disk_idx == r6s->qd_idx) &&
+ test_bit(STRIPE_OP_CHECK, &sh->ops.pending))
+ return ~0;
- if (!test_bit(R5_LOCKED, &dev->flags) &&
- !test_bit(R5_UPTODATE, &dev->flags) &&
- (dev_q->toread || (dev_q->towrite &&
- !test_bit(R5_OVERWRITE, &dev->flags)) ||
- s->syncing || s->expanding ||
- (s->failed >= 1 &&
- (sq->dev[r6s->failed_num[0]].toread ||
- s->to_write)) ||
- (s->failed >= 2 &&
- (sq->dev[r6s->failed_num[1]].toread ||
- s->to_write)))) {
- /* we would like to get this block, possibly
- * by computing it, but we might not be able to
+ /* 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_q->toread ||
+ (dev_q->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
+ s->syncing || s->expanding ||
+ (s->failed >= 1 && (failed_dev_q[0]->toread ||
+ (failed_dev_q[0]->towrite &&
+ !test_bit(R5_OVERWRITE,&failed_dev[0]->flags)))) ||
+ (s->failed >= 2 && (failed_dev_q[1]->toread ||
+ (failed_dev_q[1]->towrite &&
+ !test_bit(R5_OVERWRITE,&failed_dev[1]->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 blocks re-reads until check
+ * operations have quiesced.
+ */
+ if ((s->uptodate == disks-1) &&
+ !test_bit(STRIPE_OP_CHECK, &sh->ops.pending)) {
+ pr_debug("Computing stripe %llu block %d\n",
+ (unsigned long long)sh->sector, disk_idx);
+ set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
+ set_bit(R5_Wantcompute, &dev->flags);
+ sh->ops.target = disk_idx;
+ sh->ops.target2 = -1; /* no second target */
+ s->req_compute = 1;
+ sh->ops.count++;
+ /* Careful: from this point on 'uptodate' is in the eye of
+ * raid_run_ops which services 'compute' operations before
+ * writes. R5_Wantcompute flags a block that will be R5_UPTODATE
+ * by the time it is needed for a subsequent operation.
*/
- if (s->uptodate == disks-1) {
- pr_debug("Computing stripe %llu block %d\n",
- (unsigned long long)sh->sector, i);
- compute_block_1(sh, i, 0);
- s->uptodate++;
- } else if ( s->uptodate == disks-2 && s->failed >= 2 ) {
- /* Computing 2-failure is *very* expensive; only
- * do it if failed >= 2
- */
- int other;
- for (other = disks; other--; ) {
- if (other == i)
- continue;
- if (!test_bit(R5_UPTODATE,
- &sh->dev[other].flags))
- break;
- }
- BUG_ON(other < 0);
- pr_debug("Computing stripe %llu blocks %d,%d\n",
- (unsigned long long)sh->sector,
- i, other);
- compute_block_2(sh, i, other);
- s->uptodate += 2;
- } else if (test_bit(R5_Insync, &dev->flags)) {
- set_bit(R5_LOCKED, &dev->flags);
- set_bit(R5_Wantread, &dev->flags);
- s->locked++;
- pr_debug("Reading block %d (sync=%d)\n",
- i, s->syncing);
+ s->uptodate++;
+ return 0; /* s->uptodate + s->compute == disks */
+ } else if ( s->uptodate == disks-2 && s->failed >= 2 ) {
+ /* Computing 2-failure is *very* expensive; only
+ * do it if failed >= 2
+ */
+ int other;
+ for (other = disks; other--; ) {
+ if (other == disk_idx)
+ continue;
+ if (!test_bit(R5_UPTODATE, &sh->dev[other].flags))
+ break;
}
+ BUG_ON(other < 0);
+ pr_debug("Computing stripe %llu blocks %d,%d\n",
+ (unsigned long long)sh->sector,
+ disk_idx, other);
+ set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
+ set_bit(R5_Wantcompute, &dev->flags);
+ set_bit(R5_Wantcompute, &sh->dev[other].flags);
+ sh->ops.target = disk_idx;
+ sh->ops.target2 = other;
+ s->req_compute = 1;
+ sh->ops.count++;
+ s->uptodate += 2;
+ } else if ((s->uptodate < disks-2) &&
+ 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) FIXME
+ */
+ set_bit(R5_LOCKED, &dev->flags);
+ set_bit(R5_Wantread, &dev->flags);
+ if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
+ sh->ops.count++;
+ s->locked++;
+ pr_debug("Reading block %d (sync=%d)\n", disk_idx,
+ s->syncing);
}
}
+
+ return ~0;
+}
+
+static void handle_issuing_new_read_requests6(struct stripe_head *sh,
+ struct stripe_head_state *s, struct r6_state *r6s,
+ int disks)
+{
+ int i;
+
+ /* Clear completed compute operations. Parity recovery
+ * (STRIPE_OP_MOD_REPAIR_PD) implies a write-back which is handled
+ * later on in this routine
+ */
+ if (test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.complete) &&
+ !test_bit(STRIPE_OP_MOD_REPAIR_PD, &sh->ops.pending)) {
+ 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_POSTXOR, &sh->ops.pending)) {
+ for (i = disks; i--;)
+ if (!__handle_issuing_new_read_requests6(sh, s, r6s,
+ i, disks))
+ break;
+ }
set_bit(STRIPE_HANDLE, &sh->state);
}
@@ -3079,11 +3155,11 @@ static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
for (i = disks; i--; ) {
struct r5dev *dev = &sh->dev[i];
/* Would I have to read this buffer for reconstruct_write */
- if (!test_bit(R5_OVERWRITE, &dev->flags)
- && i != pd_idx && i != qd_idx
- && (!test_bit(R5_LOCKED, &dev->flags)
- ) &&
- !test_bit(R5_UPTODATE, &dev->flags)) {
+ if (!test_bit(R5_OVERWRITE, &dev->flags) &&
+ i != pd_idx && i != qd_idx &&
+ !test_bit(R5_LOCKED, &dev->flags) &&
+ !test_bit(R5_UPTODATE, &dev->flags) &&
+ !test_bit(R5_Wantcompute, &dev->flags)) {
if (test_bit(R5_Insync, &dev->flags)) rcw++;
else {
pr_debug("raid6: must_compute: "
@@ -3100,18 +3176,19 @@ static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
/* want reconstruct write, but need to get some data */
for (i = disks; i--; ) {
struct r5dev *dev = &sh->dev[i];
- if (!test_bit(R5_OVERWRITE, &dev->flags)
- && !(s->failed == 0 && (i == pd_idx || i == qd_idx))
- && !test_bit(R5_LOCKED, &dev->flags) &&
+ if (!(!test_bit(R5_OVERWRITE, &dev->flags) &&
+ !(s->failed == 0 && (i == pd_idx || i == qd_idx)) &&
+ !test_bit(R5_LOCKED, &dev->flags) &&
!test_bit(R5_UPTODATE, &dev->flags) &&
- test_bit(R5_Insync, &dev->flags)) {
- pr_debug("Read_old stripe %llu "
- "block %d for Reconstruct\n",
- (unsigned long long)sh->sector, i);
- set_bit(R5_LOCKED, &dev->flags);
- set_bit(R5_Wantread, &dev->flags);
- s->locked++;
- }
+ !test_bit(R5_Wantcompute, &dev->flags) &&
+ test_bit(R5_Insync, &dev->flags)))
+ continue;
+ pr_debug("Read_old stripe %llu "
+ "block %d for Reconstruct\n",
+ (unsigned long long)sh->sector, i);
+ set_bit(R5_LOCKED, &dev->flags);
+ set_bit(R5_Wantread, &dev->flags);
+ s->locked++;
}
/* now if nothing is locked, and if we have enough data, we can start a
* write request
@@ -3131,13 +3208,26 @@ static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
case 0:
BUG();
case 1:
- compute_block_1(sh, r6s->failed_num[0], 0);
+ set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
+ set_bit(R5_Wantcompute,
+ &sh->dev[r6s->failed_num[0]].flags);
+ sh->ops.target = r6s->failed_num[0];
+ sh->ops.target2 = -1; /* no second target */
+ s->req_compute = 1;
+ sh->ops.count++;
break;
case 2:
- compute_block_2(sh, r6s->failed_num[0],
- r6s->failed_num[1]);
+ set_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending);
+ set_bit(R5_Wantcompute,
+ &sh->dev[r6s->failed_num[0]].flags);
+ set_bit(R5_Wantcompute,
+ &sh->dev[r6s->failed_num[1]].flags);
+ sh->ops.target = r6s->failed_num[0];
+ sh->ops.target2 = r6s->failed_num[1];
+ s->req_compute = 1;
+ sh->ops.count++;
break;
- default: /* This request should have been failed? */
+ default:
BUG();
}
}
@@ -3737,6 +3827,8 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
if (test_bit(R5_LOCKED, &dev->flags)) s.locked++;
if (test_bit(R5_UPTODATE, &dev->flags)) s.uptodate++;
+ if (test_bit(R5_Wantcompute, &dev->flags))
+ BUG_ON(++s.compute > 2);
if (dev_q->toread)
s.to_read++;
@@ -3803,7 +3895,8 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
* or to load a block that is being partially written.
*/
if (s.to_read || s.non_overwrite || (s.to_write && s.failed) ||
- (s.syncing && (s.uptodate < disks)) || s.expanding)
+ (s.syncing && (s.uptodate + s.compute < disks)) || s.expanding ||
+ test_bit(STRIPE_OP_COMPUTE_BLK, &sh->ops.pending))
handle_issuing_new_read_requests6(sh, &s, &r6s, disks);
/* Now we check to see if any write operations have recently
--
Yuri Tikhonov, Senior Software Engineer
Emcraft Systems, www.emcraft.com
-
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