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?
+ }
+
if (pio->ret > 0) {
ploop_pio_advance(pio, pio->ret);
ploop_queue_resubmit(pio);
- return;
- } else {
- pio->bi_status = BLK_STS_IOERR;
- goto check_da;
}
+ return;
}
if (static_branch_unlikely(&ploop_standby_check))
ploop_check_standby_mode(pio->ploop, pio->ret);
pio->bi_status = errno_to_blk_status(pio->ret);
}
-check_da:
if (pio->is_data_alloc) {
completed = ploop_data_pio_end(pio);
if (!completed)
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