On 13.12.24 15:24, Andrey Zhadchenko wrote:
On 12/13/24 14:20, Alexander Atanasov wrote:
On 13.12.24 15:17, Andrey Zhadchenko wrote:
On 12/5/24 22:56, Alexander Atanasov wrote:
direct IO write result ENOTBLK or 0(in ext4 case) means
retry IO in buffered mode. We wrongly assumed that it is
a short write and handled it incorrectly
Since we can not retry in buffered mode, code is not ready
for it. Take a different route. This error happens if
page invalidation fails, which is a very rare situation.
So call synchronize_rcu() and just resubmit pio.
https://virtuozzo.atlassian.net/browse/VSTOR-91821
Suggested-by: Alexey Kuznetsov <kuz...@virtuozzo.com>
Signed-off-by: Alexander Atanasov <alexander.atana...@virtuozzo.com>
---
drivers/md/dm-ploop-map.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index a03e1af3fd87..482022d6b60b 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -1312,24 +1312,31 @@ static void ploop_data_rw_complete(struct
pio *pio)
bool completed;
if (pio->ret != pio->bi_iter.bi_size) {
- if (pio->ret >= 0) {
- /* Partial IO */
- WARN_ON_ONCE(pio->ret == 0);
- /* Do not resubmit zero length pio */
+ if (pio->ret >= 0 || pio->ret == -ENOTBLK) {
+ /* Partial IO or request to retry in buffered mode */
+ if (pio->ret == 0 || pio->ret == -ENOTBLK) {
+ /*
+ * ENOTBLK means we should retry in buffered io
+ * but we can not, so try again in DIO
+ * ext4 returns 0 for ENOTBLK
+ */
+ struct ploop *ploop = pio->ploop;
+
+ PL_ERR("ret = 0 bi_size=%d\n", pio->bi_iter.bi_size);
+ synchronize_rcu();
+ ploop_queue_resubmit(pio);
Can this re-occur the second or third time? Should we limit how many
times we can resubmit?
It should not, it happens very rarely - even if we add a limit we do
not have what else to do in that case, can not do buffered IO which
will results in dirty pages and make this appear even more .
Well I think we should end the pio with error then. Otherwise we may
have forever stuck request
I've added a retry logic and end pio with IO error if it fails 3 times -
so there is no stuck request.
--
Regards,
Alexander Atanasov
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