Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e4d84909dd48b5e5806a5d18b881e1ca1610ba9b
Commit: e4d84909dd48b5e5806a5d18b881e1ca1610ba9b
Parent: 6247cdc2cd334dad0ea5428245a7d8f4b075f21e
Author: Dan Williams <[EMAIL PROTECTED]>
AuthorDate: Mon Sep 24 10:06:13 2007 -0700
Committer: Dan Williams <[EMAIL PROTECTED]>
CommitDate: Mon Sep 24 13:23:35 2007 -0700
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 <[EMAIL PROTECTED]>
[EMAIL PROTECTED]: simpler fix for bug 1 than moving code]
Signed-off-by: NeilBrown <[EMAIL PROTECTED]>
Signed-off-by: Dan Williams <[EMAIL PROTECTED]>
---
drivers/md/raid5.c | 17 +++++++----------
1 files changed, 7 insertions(+), 10 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 4d63773..f96dea9 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);
}
-
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