Currently push_backup device cannot be stopped if any process
in a system is waiting next push block via push_backup_read. This
means we have to kill that process or thread to release push_backup
device, as it holds pb->ctl_rwsem.
Change code so push_backup is marked !alive and all waiters are
woken up before acquiring the lock. This is safe to do as pb->alive
is only used for determining if we should postpone new I/O and
process user push_backup_read/push_backup_write. All operations
like releasing I/O or memory will be done with acquired lock as
soon as all kicked readers exit syscall.
Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com>
---
drivers/md/dm-push-backup.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/md/dm-push-backup.c b/drivers/md/dm-push-backup.c
index 1500d0681cee..bd021560a3e9 100644
--- a/drivers/md/dm-push-backup.c
+++ b/drivers/md/dm-push-backup.c
@@ -575,6 +575,17 @@ static int pb_message(struct dm_target *ti, unsigned int
argc, char **argv,
if (argc < 1)
goto out;
+ if (!strcmp(argv[0], "push_backup_stop")) {
+ if (argc != 1)
+ goto out;
+
+ if (!pb->map)
+ return -EBADF;
+
+ pb->alive = false;
+ wake_up_interruptible(&pb->waitq); /* pb->alive = false */
+ }
+
write = msg_wants_down_write(argv[0]);
if (write)
ret = down_write_killable(&pb->ctl_rwsem);
@@ -593,8 +604,6 @@ static int pb_message(struct dm_target *ti, unsigned int
argc, char **argv,
goto unlock;
ret = push_backup_start(pb, val, (void *)val2);
} else if (!strcmp(argv[0], "push_backup_stop")) {
- if (argc != 1)
- goto unlock;
ret = push_backup_stop(pb, result, maxlen);
} else if (!strcmp(argv[0], "push_backup_read")) {
if (argc != 1)
--
2.31.1
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