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Subject[PATCH 026 of 29] md: md: replace STRIPE_OP_{BIODRAIN,PREXOR,POSTXOR} with 'reconstruct_states'

From: Dan Williams <dan.j.williams@intel.com>

Track the state of reconstruct operations (recalculating the parity block
usually due to incoming writes, or as part of array expansion) Reduces the
scope of the STRIPE_OP_{BIODRAIN,PREXOR,POSTXOR} flags to only tracking whether
a reconstruct operation has been requested via the ops_request field of struct
stripe_head_state.
This is the final step in the removal of ops.{pending,ack,complete,count}, i.e.
the STRIPE_OP_{BIODRAIN,PREXOR,POSTXOR} flags only request an operation and do
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>

### Diffstat output
./drivers/md/raid5.c | 204 +++++++++++++------------------------------
./include/linux/raid/raid5.h | 9 -
2 files changed, 63 insertions(+), 150 deletions(-)
diff .prev/drivers/md/raid5.c ./drivers/md/raid5.c
--- .prev/drivers/md/raid5.c 2008-06-27 16:42:34.000000000 +1000
+++ ./drivers/md/raid5.c 2008-06-27 16:42:36.000000000 +1000
@@ -122,6 +122,13 @@ static void return_io(struct bio *return

static void print_raid5_conf (raid5_conf_t *conf);

+static int stripe_operations_active(struct stripe_head *sh)
+{
+ return sh->check_state || sh->reconstruct_state ||
+ test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
+ test_bit(STRIPE_COMPUTE_RUN, &sh->state);
+}
+
static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
{
if (atomic_dec_and_test(&sh->count)) {
@@ -141,7 +148,7 @@ static void __release_stripe(raid5_conf_
}
md_wakeup_thread(conf->mddev->thread);
} else {
- BUG_ON(sh->ops.pending);
+ BUG_ON(stripe_operations_active(sh));
if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
atomic_dec(&conf->preread_active_stripes);
if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD)
@@ -243,7 +250,7 @@ static void init_stripe(struct stripe_he

BUG_ON(atomic_read(&sh->count) != 0);
BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
- BUG_ON(sh->ops.pending || sh->ops.ack || sh->ops.complete);
+ BUG_ON(stripe_operations_active(sh));

CHECK_DEVLOCK();
pr_debug("init_stripe called, stripe %llu\n",
@@ -344,47 +351,6 @@ static struct stripe_head *get_active_st
return sh;
}

-/* test_and_ack_op() ensures that we only dequeue an operation once */
-#define test_and_ack_op(op, pend) \
-do { \
- if (test_bit(op, &sh->ops.pending) && \
- !test_bit(op, &sh->ops.complete)) { \
- if (test_and_set_bit(op, &sh->ops.ack)) \
- clear_bit(op, &pend); \
- else \
- ack++; \
- } else \
- clear_bit(op, &pend); \
-} while (0)
-
-/* find new work to run, do not resubmit work that is already
- * in flight
- */
-static unsigned long get_stripe_work(struct stripe_head *sh)
-{
- unsigned long pending;
- int ack = 0;
-
- pending = sh->ops.pending;
-
- test_and_ack_op(STRIPE_OP_BIOFILL, pending);
- test_and_ack_op(STRIPE_OP_COMPUTE_BLK, pending);
- test_and_ack_op(STRIPE_OP_PREXOR, pending);
- test_and_ack_op(STRIPE_OP_BIODRAIN, pending);
- test_and_ack_op(STRIPE_OP_POSTXOR, pending);
- test_and_ack_op(STRIPE_OP_CHECK, pending);
-
- sh->ops.count -= ack;
- if (unlikely(sh->ops.count < 0)) {
- printk(KERN_ERR "pending: %#lx ops.pending: %#lx ops.ack: %#lx "
- "ops.complete: %#lx\n", pending, sh->ops.pending,
- sh->ops.ack, sh->ops.complete);
- BUG();
- }
-
- return pending;
-}
-
static void
raid5_end_read_request(struct bio *bi, int error);
static void
@@ -609,7 +575,7 @@ static void ops_complete_compute5(void *
}

static struct dma_async_tx_descriptor *
-ops_run_compute5(struct stripe_head *sh, unsigned long pending)
+ops_run_compute5(struct stripe_head *sh, unsigned long ops_request)
{
/* kernel stack size limits the total number of disks */
int disks = sh->disks;
@@ -640,7 +606,7 @@ ops_run_compute5(struct stripe_head *sh,
ops_complete_compute5, sh);

/* ack now if postxor is not set to be run */
- if (tx && !test_bit(STRIPE_OP_POSTXOR, &pending))
+ if (tx && !test_bit(STRIPE_OP_POSTXOR, &ops_request))
async_tx_ack(tx);

return tx;
@@ -652,8 +618,6 @@ static void ops_complete_prexor(void *st

pr_debug("%s: stripe %llu\n", __func__,
(unsigned long long)sh->sector);
-
- set_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
}

static struct dma_async_tx_descriptor *
@@ -686,7 +650,7 @@ ops_run_prexor(struct stripe_head *sh, s

static struct dma_async_tx_descriptor *
ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
- unsigned long pending)
+ unsigned long ops_request)
{
int disks = sh->disks;
int pd_idx = sh->pd_idx, i;
@@ -694,7 +658,7 @@ ops_run_biodrain(struct stripe_head *sh,
/* check if prexor is active which means only process blocks
* that are part of a read-modify-write (Wantprexor)
*/
- int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
+ int prexor = test_bit(STRIPE_OP_PREXOR, &ops_request);

pr_debug("%s: stripe %llu\n", __func__,
(unsigned long long)sh->sector);
@@ -744,7 +708,7 @@ static void ops_complete_postxor(void *s
pr_debug("%s: stripe %llu\n", __func__,
(unsigned long long)sh->sector);

- set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
+ sh->reconstruct_state = reconstruct_state_result;
set_bit(STRIPE_HANDLE, &sh->state);
release_stripe(sh);
}
@@ -763,16 +727,14 @@ static void ops_complete_write(void *str
set_bit(R5_UPTODATE, &dev->flags);
}

- set_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
- set_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
-
+ sh->reconstruct_state = reconstruct_state_drain_result;
set_bit(STRIPE_HANDLE, &sh->state);
release_stripe(sh);
}

static void
ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
- unsigned long pending)
+ unsigned long ops_request)
{
/* kernel stack size limits the total number of disks */
int disks = sh->disks;
@@ -780,7 +742,7 @@ ops_run_postxor(struct stripe_head *sh,

int count = 0, pd_idx = sh->pd_idx, i;
struct page *xor_dest;
- int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
+ int prexor = test_bit(STRIPE_OP_PREXOR, &ops_request);
unsigned long flags;
dma_async_tx_callback callback;

@@ -807,7 +769,7 @@ ops_run_postxor(struct stripe_head *sh,
}

/* check whether this postxor is part of a write */
- callback = test_bit(STRIPE_OP_BIODRAIN, &pending) ?
+ callback = test_bit(STRIPE_OP_BIODRAIN, &ops_request) ?
ops_complete_write : ops_complete_postxor;

/* 1/ if we prexor'd then the dest is reused as a source
@@ -868,8 +830,7 @@ static void ops_run_check(struct stripe_
ops_complete_check, sh);
}

-static void raid5_run_ops(struct stripe_head *sh, unsigned long pending,
- unsigned long ops_request)
+static void raid5_run_ops(struct stripe_head *sh, unsigned long ops_request)
{
int overlap_clear = 0, i, disks = sh->disks;
struct dma_async_tx_descriptor *tx = NULL;
@@ -880,18 +841,18 @@ static void raid5_run_ops(struct stripe_
}

if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request))
- tx = ops_run_compute5(sh, pending);
+ tx = ops_run_compute5(sh, ops_request);

- if (test_bit(STRIPE_OP_PREXOR, &pending))
+ if (test_bit(STRIPE_OP_PREXOR, &ops_request))
tx = ops_run_prexor(sh, tx);

- if (test_bit(STRIPE_OP_BIODRAIN, &pending)) {
- tx = ops_run_biodrain(sh, tx, pending);
+ if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
+ tx = ops_run_biodrain(sh, tx, ops_request);
overlap_clear++;
}

- if (test_bit(STRIPE_OP_POSTXOR, &pending))
- ops_run_postxor(sh, tx, pending);
+ if (test_bit(STRIPE_OP_POSTXOR, &ops_request))
+ ops_run_postxor(sh, tx, ops_request);

if (test_bit(STRIPE_OP_CHECK, &ops_request))
ops_run_check(sh);
@@ -1684,11 +1645,11 @@ static void compute_block_2(struct strip
}
}

-static int
-handle_write_operations5(struct stripe_head *sh, int rcw, int expand)
+static void
+handle_write_operations5(struct stripe_head *sh, struct stripe_head_state *s,
+ int rcw, int expand)
{
int i, pd_idx = sh->pd_idx, disks = sh->disks;
- int locked = 0;

if (rcw) {
/* if we are not expanding this is a proper write request, and
@@ -1696,12 +1657,12 @@ handle_write_operations5(struct stripe_h
* stripe cache
*/
if (!expand) {
- set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
- sh->ops.count++;
- }
+ sh->reconstruct_state = reconstruct_state_drain_run;
+ set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
+ } else
+ sh->reconstruct_state = reconstruct_state_run;

- set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
- sh->ops.count++;
+ set_bit(STRIPE_OP_POSTXOR, &s->ops_request);

for (i = disks; i--; ) {
struct r5dev *dev = &sh->dev[i];
@@ -1710,21 +1671,20 @@ handle_write_operations5(struct stripe_h
set_bit(R5_LOCKED, &dev->flags);
if (!expand)
clear_bit(R5_UPTODATE, &dev->flags);
- locked++;
+ s->locked++;
}
}
- if (locked + 1 == disks)
+ if (s->locked + 1 == disks)
if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
atomic_inc(&sh->raid_conf->pending_full_writes);
} else {
BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));

- set_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
- set_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
- set_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
-
- sh->ops.count += 3;
+ sh->reconstruct_state = reconstruct_state_drain_run;
+ set_bit(STRIPE_OP_PREXOR, &s->ops_request);
+ set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
+ set_bit(STRIPE_OP_POSTXOR, &s->ops_request);

for (i = disks; i--; ) {
struct r5dev *dev = &sh->dev[i];
@@ -1742,7 +1702,7 @@ handle_write_operations5(struct stripe_h
set_bit(R5_Wantprexor, &dev->flags);
set_bit(R5_LOCKED, &dev->flags);
clear_bit(R5_UPTODATE, &dev->flags);
- locked++;
+ s->locked++;
}
}
}
@@ -1752,13 +1712,11 @@ handle_write_operations5(struct stripe_h
*/
set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
- locked++;
+ s->locked++;

- pr_debug("%s: stripe %llu locked: %d pending: %lx\n",
+ pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
__func__, (unsigned long long)sh->sector,
- locked, sh->ops.pending);
-
- return locked;
+ s->locked, s->ops_request);
}

/*
@@ -2005,8 +1963,7 @@ static void handle_issuing_new_read_requ
* midst of changing due to a write
*/
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)) {
+ !sh->reconstruct_state) {
for (i = disks; i--; )
if (__handle_issuing_new_read_requests5(
sh, s, i, disks) == 0)
@@ -2211,7 +2168,7 @@ static void handle_issuing_new_write_req
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);
+ handle_write_operations5(sh, s, rcw == 0, 0);
}

static void handle_issuing_new_write_requests6(raid5_conf_t *conf,
@@ -2581,15 +2538,14 @@ static void handle_stripe5(struct stripe
struct bio *return_bi = NULL;
struct stripe_head_state s;
struct r5dev *dev;
- unsigned long pending = 0;
mdk_rdev_t *blocked_rdev = NULL;
int prexor;

memset(&s, 0, sizeof(s));
- pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d "
- "ops=%lx:%lx:%lx\n", (unsigned long long)sh->sector, sh->state,
- atomic_read(&sh->count), sh->pd_idx,
- sh->ops.pending, sh->ops.ack, sh->ops.complete);
+ pr_debug("handling stripe %llu, state=%#lx cnt=%d, pd_idx=%d check:%d "
+ "reconstruct:%d\n", (unsigned long long)sh->sector, sh->state,
+ atomic_read(&sh->count), sh->pd_idx, sh->check_state,
+ sh->reconstruct_state);

spin_lock(&sh->lock);
clear_bit(STRIPE_HANDLE, &sh->state);
@@ -2703,34 +2659,12 @@ static void handle_stripe5(struct stripe
/* Now we check to see if any write operations have recently
* completed
*/
-
- /* leave prexor set until postxor is done, allows us to distinguish
- * a rmw from a rcw during biodrain
- */
prexor = 0;
- if (test_bit(STRIPE_OP_PREXOR, &sh->ops.complete) &&
- test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
-
- prexor = 1;
- clear_bit(STRIPE_OP_PREXOR, &sh->ops.complete);
- clear_bit(STRIPE_OP_PREXOR, &sh->ops.ack);
- clear_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
-
+ if (sh->reconstruct_state == reconstruct_state_drain_result) {
+ sh->reconstruct_state = reconstruct_state_idle;
for (i = disks; i--; )
- clear_bit(R5_Wantprexor, &sh->dev[i].flags);
- }
-
- /* if only POSTXOR is set then this is an 'expand' postxor */
- if (test_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete) &&
- test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete)) {
-
- clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.complete);
- clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.ack);
- clear_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending);
-
- clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
- clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
- clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
+ prexor += test_and_clear_bit(R5_Wantprexor,
+ &sh->dev[i].flags);

/* All the 'written' buffers and the parity block are ready to
* be written back to disk
@@ -2763,8 +2697,7 @@ static void handle_stripe5(struct stripe
* 2/ A 'check' operation is in flight, as it may clobber the parity
* block.
*/
- if (s.to_write && !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending) &&
- !sh->check_state)
+ if (s.to_write && !sh->reconstruct_state && !sh->check_state)
handle_issuing_new_write_requests5(conf, sh, &s, disks);

/* maybe we need to check and possibly fix the parity for this stripe
@@ -2805,18 +2738,10 @@ static void handle_stripe5(struct stripe
}
}

- /* Finish postxor operations initiated by the expansion
- * process
- */
- if (test_bit(STRIPE_OP_POSTXOR, &sh->ops.complete) &&
- !test_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending)) {
-
+ /* Finish reconstruct operations initiated by the expansion process */
+ if (sh->reconstruct_state == reconstruct_state_result) {
+ sh->reconstruct_state = reconstruct_state_idle;
clear_bit(STRIPE_EXPANDING, &sh->state);
-
- clear_bit(STRIPE_OP_POSTXOR, &sh->ops.pending);
- clear_bit(STRIPE_OP_POSTXOR, &sh->ops.ack);
- clear_bit(STRIPE_OP_POSTXOR, &sh->ops.complete);
-
for (i = conf->raid_disks; i--; )
set_bit(R5_Wantwrite, &sh->dev[i].flags);
set_bit(R5_LOCKED, &dev->flags);
@@ -2824,15 +2749,13 @@ static void handle_stripe5(struct stripe
}

if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
- !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
+ !sh->reconstruct_state) {
/* Need to write out all blocks after computing parity */
sh->disks = conf->raid_disks;
sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
conf->raid_disks);
- s.locked += handle_write_operations5(sh, 1, 1);
- } else if (s.expanded &&
- s.locked == 0 &&
- !test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
+ handle_write_operations5(sh, &s, 1, 1);
+ } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
clear_bit(STRIPE_EXPAND_READY, &sh->state);
atomic_dec(&conf->reshape_stripes);
wake_up(&conf->wait_for_overlap);
@@ -2843,9 +2766,6 @@ static void handle_stripe5(struct stripe
!test_bit(STRIPE_COMPUTE_RUN, &sh->state))
handle_stripe_expansion(conf, sh, NULL);

- if (sh->ops.count)
- pending = get_stripe_work(sh);
-
unlock:
spin_unlock(&sh->lock);

@@ -2853,8 +2773,8 @@ static void handle_stripe5(struct stripe
if (unlikely(blocked_rdev))
md_wait_for_blocked_rdev(blocked_rdev, conf->mddev);

- if (pending || s.ops_request)
- raid5_run_ops(sh, pending, s.ops_request);
+ if (s.ops_request)
+ raid5_run_ops(sh, s.ops_request);

ops_run_io(sh, &s);

diff .prev/include/linux/raid/raid5.h ./include/linux/raid/raid5.h
--- .prev/include/linux/raid/raid5.h 2008-06-27 16:42:34.000000000 +1000
+++ ./include/linux/raid/raid5.h 2008-06-27 16:42:36.000000000 +1000
@@ -205,19 +205,12 @@ struct stripe_head {
int bm_seq; /* sequence number for bitmap flushes */
int disks; /* disks in stripe */
enum check_states check_state;
+ enum reconstruct_states reconstruct_state;
/* stripe_operations
- * @pending - pending ops flags (set for request->issue->complete)
- * @ack - submitted ops flags (set for issue->complete)
- * @complete - completed ops flags (set for complete)
* @target - STRIPE_OP_COMPUTE_BLK target
- * @count - raid5_runs_ops is set to run when this is non-zero
*/
struct stripe_operations {
- unsigned long pending;
- unsigned long ack;
- unsigned long complete;
int target;
- int count;
u32 zero_sum_result;
} ops;
struct r5dev {

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