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Date: Fri, 27 Jun 2008 16:52:04 +1000
From: NeilBrown <neilb@...e.de>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Dan Williams <dan.j.williams@...el.com>
Subject: [PATCH 025 of 29] md: md: replace STRIPE_OP_COMPUTE_BLK with STRIPE_COMPUTE_RUN
From: Dan Williams <dan.j.williams@...el.com>
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 <dan.j.williams@...el.com>
Signed-off-by: Neil Brown <neilb@...e.de>
### Diffstat output
./drivers/md/raid5.c | 65 ++++++++++++++-------------------------------------
1 file changed, 18 insertions(+), 47 deletions(-)
diff .prev/drivers/md/raid5.c ./drivers/md/raid5.c
--- .prev/drivers/md/raid5.c 2008-06-27 16:22:05.000000000 +1000
+++ ./drivers/md/raid5.c 2008-06-27 16:22:06.000000000 +1000
@@ -604,8 +604,6 @@ static void ops_complete_compute5(void *
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_
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_req
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_req
(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_req
*/
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_requ
{
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_req
* 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_
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
* 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
*/
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
}
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
}
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:
--
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