[PATCH 10/16] md: satisfy raid5 read requests via raid5_run_ops

Dan Williams
2007-05-02T06:19:45Z

Use raid5_run_ops to carry out the memory copies for a raid5 read request.

Changelog:
* cleanup to_read and to_fill accounting
* do not fail reads that have reached the cache

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---

drivers/md/raid5.c | 61 ++++++++++++++++++++++++++--------------------------
1 files changed, 30 insertions(+), 31 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f8a4522..6bde174 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1998,7 +1998,7 @@ static void handle_stripe5(struct stripe_head *sh)
int i;
int syncing, expanding, expanded;
int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
- int compute=0, req_compute=0, non_overwrite=0;
+ int to_fill=0, compute=0, req_compute=0, non_overwrite=0;
int failed_num=0;
struct r5dev *dev;
unsigned long pending=0;
@@ -2022,37 +2022,29 @@ static void handle_stripe5(struct stripe_head *sh)
dev = &sh->dev[i];
clear_bit(R5_Insync, &dev->flags);

- PRINTK("check %d: state 0x%lx read %p write %p written %p\n",
- i, dev->flags, dev->toread, dev->towrite, dev->written);
- /* maybe we can reply to a read */
- if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread) {
- struct bio *rbi, *rbi2;
- PRINTK("Return read for disc %d\n", i);
- spin_lock_irq(&conf->device_lock);
- rbi = dev->toread;
- dev->toread = NULL;
- if (test_and_clear_bit(R5_Overlap, &dev->flags))
- wake_up(&conf->wait_for_overlap);
- spin_unlock_irq(&conf->device_lock);
- while (rbi && rbi->bi_sector < dev->sector + STRIPE_SECTORS) {
- copy_data(0, rbi, dev->page, dev->sector);
- rbi2 = r5_next_bio(rbi, dev->sector);
- spin_lock_irq(&conf->device_lock);
- if (--rbi->bi_phys_segments == 0) {
- rbi->bi_next = return_bi;
- return_bi = rbi;
- }
- spin_unlock_irq(&conf->device_lock);
- rbi = rbi2;
- }
- }
+ PRINTK("check %d: state 0x%lx toread %p read %p write %p written %p\n",
+ i, dev->flags, dev->toread, dev->read, dev->towrite, dev->written);
+
+ /* maybe we can request a biofill operation
+ *
+ * new wantfill requests are only permitted while
+ * STRIPE_OP_BIOFILL is clear
+ */
+ if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
+ !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
+ set_bit(R5_Wantfill, &dev->flags);

/* now count some things */
if (test_bit(R5_LOCKED, &dev->flags)) locked++;
if (test_bit(R5_UPTODATE, &dev->flags)) uptodate++;
+
+ if (test_bit(R5_Wantfill, &dev->flags))
+ to_fill++;
+ else if (dev->toread)
+ to_read++;
+
if (test_bit(R5_Wantcompute, &dev->flags)) BUG_ON(++compute > 1);

- if (dev->toread) to_read++;
if (dev->towrite) {
to_write++;
if (!test_bit(R5_OVERWRITE, &dev->flags))
@@ -2073,9 +2065,13 @@ static void handle_stripe5(struct stripe_head *sh)
set_bit(R5_Insync, &dev->flags);
}
rcu_read_unlock();
+
+ if (to_fill && !test_and_set_bit(STRIPE_OP_BIOFILL, &sh->ops.pending))
+ sh->ops.count++;
+
PRINTK("locked=%d uptodate=%d to_read=%d"
- " to_write=%d failed=%d failed_num=%d\n",
- locked, uptodate, to_read, to_write, failed, failed_num);
+ " to_write=%d to_fill=%d failed=%d failed_num=%d\n",
+ locked, uptodate, to_read, to_write, to_fill, failed, failed_num);
/* check if the array has lost two devices and, if so, some requests might
* need to be failed
*/
@@ -2127,9 +2123,12 @@ static void handle_stripe5(struct stripe_head *sh)
bi = bi2;
}

- /* fail any reads if this device is non-operational */
- if (!test_bit(R5_Insync, &sh->dev[i].flags) ||
- test_bit(R5_ReadError, &sh->dev[i].flags)) {
+ /* fail any reads if this device is non-operational and
+ * the data has not reached the cache yet.
+ */
+ if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
+ (!test_bit(R5_Insync, &sh->dev[i].flags) ||
+ test_bit(R5_ReadError, &sh->dev[i].flags))) {
bi = sh->dev[i].toread;
sh->dev[i].toread = NULL;
if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))