OK, so I finally got back to this. Just FYI, a slight adjustment to
the patch was needed (bitmap_info now has the max_write_behind field).
It's attached. You need both the barrier-retry-fix-2 patch that I
posted a while back and this one.
Thanks,
Paul
On Tue, Feb 1, 2011 at 8:04 PM, Paul Clements <paul.clements@xxxxxxxxxxx> wrote:
> On Tue, Feb 1, 2011 at 7:32 PM, NeilBrown <neilb@xxxxxxx> wrote:
>> On Tue, 1 Feb 2011 15:45:16 -0500 Paul Clements <paul.clements@xxxxxxxxxxx>
>> wrote:
>> Disabling behind-writes for all barrier requests would be quite easy, but it
>> might negate a lot of the value of behind writes
>
> Agreed...
>
>> I think the best option is to reject barrier writes if there are any
>> behind-write devices. That would be reasonably safe and reasonably
>> consistent.
>
> Yeah, I was leaning toward this.
>
>> So maybe something like this??
>
> Yes, I think that would work.
>
> Thanks,
> Paul
>
--- ./drivers/md/bitmap.c.PRISTINE 2011-02-23 17:40:26.633270814 -0500
+++ ./drivers/md/bitmap.c 2011-02-23 14:47:38.652434745 -0500
@@ -1298,8 +1298,7 @@ int bitmap_startwrite(struct bitmap *bit
if (bw > bitmap->behind_writes_used)
bitmap->behind_writes_used = bw;
- PRINTK(KERN_DEBUG "inc write-behind count %d/%d\n",
- bw, bitmap->max_write_behind);
+ PRINTK(KERN_DEBUG "inc write-behind count %d\n", bw);
}
while (sectors) {
@@ -1357,8 +1356,8 @@ void bitmap_endwrite(struct bitmap *bitm
if (!bitmap) return;
if (behind) {
atomic_dec(&bitmap->behind_writes);
- PRINTK(KERN_DEBUG "dec write-behind count %d/%d\n",
- atomic_read(&bitmap->behind_writes), bitmap->max_write_behind);
+ PRINTK(KERN_DEBUG "dec write-behind count %d\n",
+ atomic_read(&bitmap->behind_writes));
}
if (bitmap->mddev->degraded)
/* Never clear bits or update events_cleared when degraded */
@@ -1713,6 +1712,10 @@ int bitmap_create(mddev_t *mddev)
if (err)
goto error;
+ /* write behind and barrier write retries are not compatible */
+ if (mddev->bitmap_info.max_write_behind)
+ mddev->barriers_work = 0;
+
bitmap->daemon_lastrun = jiffies;
bitmap->chunkshift = ffz(~mddev->bitmap_info.chunksize);
