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md: replace STRIPE_OP_COMPUTE_BLK with STRIPE_COMPUTE_RUN
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From: Dan Williams <dan.j.williams@intel.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@intel.com>
Signed-off-by: Neil Brown <neilb@suse.de>
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Dan Williams authored and Neil Brown committed Jun 27, 2008
1 parent 83de75c commit 976ea8d
Showing 1 changed file with 18 additions and 47 deletions.
65 changes: 18 additions & 47 deletions drivers/md/raid5.c
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Original file line number Diff line number Diff line change
Expand Up @@ -604,8 +604,6 @@ static void ops_complete_compute5(void *stripe_head_ref)
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);
}
Expand Down Expand Up @@ -881,8 +879,7 @@ static void raid5_run_ops(struct stripe_head *sh, unsigned long pending,
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))
Expand Down Expand Up @@ -1960,12 +1957,6 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
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 ||
Expand All @@ -1974,23 +1965,16 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
(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
Expand All @@ -1999,12 +1983,7 @@ static int __handle_issuing_new_read_requests5(struct stripe_head *sh,
*/
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++;
Expand All @@ -2021,20 +2000,13 @@ static void handle_issuing_new_read_requests5(struct stripe_head *sh,
{
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)
Expand Down Expand Up @@ -2236,10 +2208,9 @@ static void handle_issuing_new_write_requests5(raid5_conf_t *conf,
* 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);
}

Expand Down Expand Up @@ -2410,6 +2381,7 @@ static void handle_parity_checks5(raid5_conf_t *conf, struct stripe_head *sh,
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);
Expand Down Expand Up @@ -2725,8 +2697,7 @@ static void handle_stripe5(struct stripe_head *sh)
* 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
Expand Down Expand Up @@ -2803,7 +2774,7 @@ static void handle_stripe5(struct stripe_head *sh)
*/
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);

Expand Down Expand Up @@ -2869,7 +2840,7 @@ static void handle_stripe5(struct stripe_head *sh)
}

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)
Expand Down Expand Up @@ -3089,7 +3060,7 @@ static void handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
}

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:
Expand Down

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