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authorDan Williams <dan.j.williams@intel.com>2007-09-24 10:06:13 -0700
committerDan Williams <dan.j.williams@intel.com>2007-09-24 13:23:35 -0700
commite4d84909dd48b5e5806a5d18b881e1ca1610ba9b (patch)
tree85aa712ebc034a31b9a2a5db2f0e7ce4951cb440
parent6247cdc2cd334dad0ea5428245a7d8f4b075f21e (diff)
downloadlinux-e4d84909dd48b5e5806a5d18b881e1ca1610ba9b.tar.gz
raid5: fix 2 bugs in ops_complete_biofill
1/ ops_complete_biofill tried to avoid calling handle_stripe since all the state necessary to return read completions is available. However the process of determining whether more read requests are pending requires locking the stripe (to block add_stripe_bio from updating dev->toead). ops_complete_biofill can run in tasklet context, so rather than upgrading all the stripe locks from spin_lock to spin_lock_bh this patch just unconditionally reschedules handle_stripe after completing the read request. 2/ ops_complete_biofill needlessly qualified processing R5_Wantfill with dev->toread. The result being that the 'biofill' pending bit is cleared before handling the pending read-completions on dev->read. R5_Wantfill can be unconditionally handled because the 'biofill' pending bit prevents new R5_Wantfill requests from being seen by ops_run_biofill and ops_complete_biofill. Found-by: Yuri Tikhonov <yur@emcraft.com> [neilb@suse.de: simpler fix for bug 1 than moving code] Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
-rw-r--r--drivers/md/raid5.c17
1 files changed, 7 insertions, 10 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 4d63773ee73..f96dea975fa 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -514,7 +514,7 @@ static void ops_complete_biofill(void *stripe_head_ref)
struct stripe_head *sh = stripe_head_ref;
struct bio *return_bi = NULL;
raid5_conf_t *conf = sh->raid_conf;
- int i, more_to_read = 0;
+ int i;
pr_debug("%s: stripe %llu\n", __FUNCTION__,
(unsigned long long)sh->sector);
@@ -522,16 +522,14 @@ static void ops_complete_biofill(void *stripe_head_ref)
/* clear completed biofills */
for (i = sh->disks; i--; ) {
struct r5dev *dev = &sh->dev[i];
- /* check if this stripe has new incoming reads */
- if (dev->toread)
- more_to_read++;
/* acknowledge completion of a biofill operation */
- /* and check if we need to reply to a read request
- */
- if (test_bit(R5_Wantfill, &dev->flags) && !dev->toread) {
+ /* and check if we need to reply to a read request,
+ * new R5_Wantfill requests are held off until
+ * !test_bit(STRIPE_OP_BIOFILL, &sh->ops.pending)
+ */
+ if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
struct bio *rbi, *rbi2;
- clear_bit(R5_Wantfill, &dev->flags);
/* The access to dev->read is outside of the
* spin_lock_irq(&conf->device_lock), but is protected
@@ -558,8 +556,7 @@ static void ops_complete_biofill(void *stripe_head_ref)
return_io(return_bi);
- if (more_to_read)
- set_bit(STRIPE_HANDLE, &sh->state);
+ set_bit(STRIPE_HANDLE, &sh->state);
release_stripe(sh);
}