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| author | Dan Williams <dan.j.williams@intel.com> | 2007-09-24 10:06:13 -0700 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2007-09-24 13:23:35 -0700 |
| commit | e4d84909dd48b5e5806a5d18b881e1ca1610ba9b (patch) | |
| tree | 85aa712ebc034a31b9a2a5db2f0e7ce4951cb440 | |
| parent | 6247cdc2cd334dad0ea5428245a7d8f4b075f21e (diff) | |
| download | linux-3.10-e4d84909dd48b5e5806a5d18b881e1ca1610ba9b.tar.gz linux-3.10-e4d84909dd48b5e5806a5d18b881e1ca1610ba9b.tar.bz2 linux-3.10-e4d84909dd48b5e5806a5d18b881e1ca1610ba9b.zip | |
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.c | 17 |
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); } |