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md: common infrastructure for running operations with raid5_run_ops 

All the handle_stripe operations that are to be transitioned to use
raid5_run_ops need a method to coherently gather work under the stripe-lock
and hand that work off to raid5_run_ops.  The 'get_stripe_work' routine
runs under the lock to read all the bits in sh->ops.pending that do not
have the corresponding bit set in sh->ops.ack.  This modified 'pending'
bitmap is then passed to raid5_run_ops for processing.

The transition from 'ack' to 'completion' does not need similar protection
as the existing release_stripe infrastructure will guarantee that
handle_stripe will run again after a completion bit is set, and
handle_stripe can tolerate a sh->ops.completed bit being set while the lock
is held.

A call to async_tx_issue_pending_all() is added to raid5d to kick the
offload engines once all pending stripe operations work has been submitted.
This enables batching of the submission and completion of operations.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-By: NeilBrown <neilb@suse.de>
This commit is contained in:
Dan Williams 2007-01-02 13:52:30 -07:00
parent 91c0092484
commit d84e0f10d3
1 changed files with 58 additions and 9 deletions
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67
drivers/md/raid5.c
View File

@ -141,6 +141,7 @@ static void __release_stripe(raid5_conf_t *conf, struct stripe_head *sh)
}
md_wakeup_thread(conf->mddev->thread);
} else {
BUG_ON(sh->ops.pending);
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)
@ -242,7 +243,8 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int
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);
CHECK_DEVLOCK();
pr_debug("init_stripe called, stripe %llu\n",
(unsigned long long)sh->sector);
@ -258,11 +260,11 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int
for (i = sh->disks; i--; ) {
struct r5dev *dev = &sh->dev[i];
if (dev->toread || dev->towrite || dev->written ||
if (dev->toread || dev->read || dev->towrite || dev->written ||
test_bit(R5_LOCKED, &dev->flags)) {
printk("sector=%llx i=%d %p %p %p %d\n",
printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
(unsigned long long)sh->sector, i, dev->toread,
dev->towrite, dev->written,
dev->read, dev->towrite, dev->written,
test_bit(R5_LOCKED, &dev->flags));
BUG();
}
@ -342,6 +344,44 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
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);
if (test_and_clear_bit(STRIPE_OP_IO, &sh->ops.pending))
ack++;
sh->ops.count -= ack;
BUG_ON(sh->ops.count < 0);
return pending;
}
static int
raid5_end_read_request(struct bio *bi, unsigned int bytes_done, int error);
static int
@ -2494,7 +2534,6 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
* schedule a write of some buffers
* return confirmation of parity correctness
*
* Parity calculations are done inside the stripe lock
* buffers are taken off read_list or write_list, and bh_cache buffers
* get BH_Lock set before the stripe lock is released.
*
@ -2507,11 +2546,13 @@ static void handle_stripe5(struct stripe_head *sh)
struct bio *return_bi = NULL;
struct stripe_head_state s;
struct r5dev *dev;
unsigned long pending = 0;
memset(&s, 0, sizeof(s));
pr_debug("handling stripe %llu, cnt=%d, pd_idx=%d\n",
(unsigned long long)sh->sector, atomic_read(&sh->count),
sh->pd_idx);
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);
spin_lock(&sh->lock);
clear_bit(STRIPE_HANDLE, &sh->state);
@ -2674,8 +2715,14 @@ static void handle_stripe5(struct stripe_head *sh)
if (s.expanding && s.locked == 0)
handle_stripe_expansion(conf, sh, NULL);
if (sh->ops.count)
pending = get_stripe_work(sh);
spin_unlock(&sh->lock);
if (pending)
raid5_run_ops(sh, pending);
return_io(return_bi);
for (i=disks; i-- ;) {
@ -3798,8 +3845,10 @@ static void raid5d (mddev_t *mddev)
handled++;
}
if (list_empty(&conf->handle_list))
if (list_empty(&conf->handle_list)) {
async_tx_issue_pending_all();
break;
}
first = conf->handle_list.next;
sh = list_entry(first, struct stripe_head, lru);