[Devel] [PATCH rh7] ploop: push_backup: copy stop status back to userspace

[Maxim Patlasov]

ploop_push_backup_stop() calls ploop_pb_destroy(). The latter saves the
return code of ploop_pb_stop() in ctl.status. But we have to do copy_to_user()
afterwards to make it visible in userspace.

Overall, if in userspace ioctl(PLOOP_IOC_PUSH_BACKUP_STOP) succeeded, the user
can check ctl.status to see how it went. Possible values are:
  0 -- OK
 >0 -- number of suspended requests "in flight"
 <0 -- a reason (like -ENOMEM or -EBADF) why CBT merge failed.

https://jira.sw.ru/browse/PSBM-47429

Signed-off-by: Maxim Patlasov <mpatlasov at virtuozzo.com>
---
 drivers/block/ploop/dev.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 880907f..96f7850 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -4683,6 +4683,7 @@ static int ploop_push_backup_stop(struct ploop_device *plo, unsigned long arg)
 {
 	struct ploop_pushbackup_desc *pbd = plo->pbd;
 	struct ploop_push_backup_stop_ctl ctl;
+	int ret;
 
 	if (plo->maintenance_type != PLOOP_MNTN_PUSH_BACKUP)
 		return -EINVAL;
@@ -4696,7 +4697,11 @@ static int ploop_push_backup_stop(struct ploop_device *plo, unsigned long arg)
 		return -EINVAL;
 	}
 
-	return ploop_pb_destroy(plo, &ctl.status);
+	ret = ploop_pb_destroy(plo, &ctl.status);
+	if (ret)
+		return ret;
+
+	return copy_to_user((void*)arg, &ctl, sizeof(ctl));
 }
 
 static int ploop_ioctl(struct block_device *bdev, fmode_t fmode, unsigned int cmd,