[Devel] [PATCH RH9 5/5] dm-qcow2: Move qcow2_get_img_name() and qcow2_get_img_fd() out of mutex

[Kirill Tkhai]

Now it is protected by target ref, so we move them out.
This allows to avoid long hang in case of this functions
are called in parallel with backup.

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 drivers/md/dm-qcow2-cmd.c |   24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/md/dm-qcow2-cmd.c b/drivers/md/dm-qcow2-cmd.c
index c64ea325e52e..bb541e4707cf 100644
--- a/drivers/md/dm-qcow2-cmd.c
+++ b/drivers/md/dm-qcow2-cmd.c
@@ -315,24 +315,28 @@ int qcow2_message(struct dm_target *ti, unsigned int argc, char **argv,
 	if (argc < 1)
 		goto out;
 
-	ret = mutex_lock_killable(&tgt->ctl_mutex);
-	if (ret)
-		goto out;
-
-	if (!strcmp(argv[0], "get_errors")) {
-		ret = qcow2_get_errors(tgt, result, maxlen);
-	} else if (!strcmp(argv[0], "get_img_fd")) {
+	if (!strcmp(argv[0], "get_img_fd")) {
 		if (argc != 2 || kstrtou32(argv[1], 10, &val)) {
 			ret = -EINVAL;
-			goto unlock;
+			goto out;
 		}
 		ret = qcow2_get_img_fd(tgt, val, result, maxlen);
+		goto out;
 	} else if (!strcmp(argv[0], "get_img_name")) {
 		if (argc != 2 || kstrtou32(argv[1], 10, &val)) {
 			ret = -EINVAL;
-			goto unlock;
+			goto out;
 		}
 		ret = qcow2_get_img_name(tgt, val, result, maxlen);
+		goto out;
+	}
+
+	ret = mutex_lock_killable(&tgt->ctl_mutex);
+	if (ret)
+		goto out;
+
+	if (!strcmp(argv[0], "get_errors")) {
+		ret = qcow2_get_errors(tgt, result, maxlen);
 	} else if (!tgt->service_operations_allowed) {
 		ret = -EBUSY; /* Suspended */
 		/* Service operations goes below: */
@@ -343,7 +347,7 @@ int qcow2_message(struct dm_target *ti, unsigned int argc, char **argv,
 	} else {
 		ret = -ENOTTY;
 	}
-unlock:
+
 	mutex_unlock(&tgt->ctl_mutex);
 out:
 	return ret;