On Monday February 5, [EMAIL PROTECTED] wrote:
> On Mon, 05 Feb 2007 20:08:39 -0800 "Kai" <[EMAIL PROTECTED]> wrote:
>
> You hit two bugs. It seems that raid5 is submitting BIOs which are larger
> than the device can accept. In response someone (probably the block layer)
> caused a page to come unlocked twice, possibly by running bi_end_io twice
> against the same BIO.
At least two bugs... there should be a prize for that :-)
Raid5 was definitely submitting a bio that was too big for the device,
and then when it got an error and went to try it the old-fashioned way
(lots of little Bi's through the stripe-cache) it messed up.
Whether that is what trigger the double-unlock I'm not yet sure.
This patch should fix the worst of the offences, but I'd like to
experiment and think a bit more before I submit it to stable.
And probably test it too - as yet I have only compile and brain
tested.
What is the chunk-size on your raid5? Presumably at least 128k ?
NeilBrown
### Diffstat output
./drivers/md/raid5.c | 40 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 38 insertions(+), 2 deletions(-)
diff .prev/drivers/md/raid5.c ./drivers/md/raid5.c
--- .prev/drivers/md/raid5.c 2007-02-06 16:16:39.000000000 +1100
+++ ./drivers/md/raid5.c 2007-02-06 16:20:57.000000000 +1100
@@ -2669,6 +2669,27 @@ static int raid5_align_endio(struct bio
return 0;
}
+static int bio_fits_rdev(struct bio *bi)
+{
+ request_queue_t *q = bdev_get_queue(bi->bi_bdev);
+
+ if ((bi->bi_size>>9) > q->max_sectors)
+ return 0;
+ blk_recount_segments(q, bi);
+ if (bi->bi_phys_segments > q->max_phys_segments ||
+ bi->bi_hw_segments > q->max_hw_segments)
+ return 0;
+
+ if (q->merge_bvec_fn)
+ /* it's too hard to apply the merge_bvec_fn at this stage,
+ * just just give up
+ */
+ return 0;
+
+ return 1;
+}
+
+
static int chunk_aligned_read(request_queue_t *q, struct bio * raid_bio)
{
mddev_t *mddev = q->queuedata;
@@ -2715,6 +2736,13 @@ static int chunk_aligned_read(request_qu
align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
align_bi->bi_sector += rdev->data_offset;
+ if (!bio_fits_rdev(align_bi)) {
+ /* too big in some way */
+ bio_put(align_bi);
+ rdev_dec_pending(rdev, mddev);
+ return 0;
+ }
+
spin_lock_irq(&conf->device_lock);
wait_event_lock_irq(conf->wait_for_stripe,
conf->quiesce == 0,
@@ -3107,7 +3135,9 @@ static int retry_aligned_read(raid5_con
last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
for (; logical_sector < last_sector;
- logical_sector += STRIPE_SECTORS, scnt++) {
+ logical_sector += STRIPE_SECTORS,
+ sector += STRIPE_SECTORS,
+ scnt++) {
if (scnt < raid_bio->bi_hw_segments)
/* already done this stripe */
@@ -3123,7 +3153,13 @@ static int retry_aligned_read(raid5_con
}
set_bit(R5_ReadError, &sh->dev[dd_idx].flags);
- add_stripe_bio(sh, raid_bio, dd_idx, 0);
+ if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
+ release_stripe(sh);
+ raid_bio->bi_hw_segments = scnt;
+ conf->retry_read_aligned = raid_bio;
+ return handled;
+ }
+
handle_stripe(sh, NULL);
release_stripe(sh);
handled++;
-
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