nvme/052: wait for namespace removal before recreating namespace

The CKI project reported that the test case nvme/052 fails occasionally
with the errors below:

  nvme/052 (tr=loop) (Test file-ns creation/deletion under one subsystem) [failed]
      runtime    ...  22.209s
      --- tests/nvme/052.out    2024-07-30 18:38:29.041716566 -0400
      +++
+/mnt/tests/gitlab.com/redhat/centos-stream/tests/kernel/kernel-tests/-/archive/production/kernel-t\
ests-production.zip/storage/blktests/nvme/nvme-loop/blktests
+/results/nodev_tr_loop/nvme/052.out.bad        2024-07-30 18:45:35.438067452 -0400
      @@ -1,2 +1,4 @@
       Running nvme/052
      +cat: /sys/block/nvme1n2/uuid: No such file or directory
      +cat: /sys/block/nvme1n2/uuid: No such file or directory
       Test complete

The test case repeats creating and removing namespaces. When the test
case removes the namespace by echoing 0 to the sysfs enable file, this
echo write does not wait for the completion of the namespace removal.
Before the removal completes, the test case recreates the namespace.
At this point, the sysfs uuid file for the old namespace still exists.
The test case misunderstands that the the sysfs uuid file would be for
the recreated namespace, and tries to read it. However, the removal
process for the old namespace deletes the sysfs uuid file at this point.
Then the read attempt fails and results in the errors.

To avoid the failure, wait for the namespace removal before recreating
the namespace. Modify nvmf_wait_for_ns() so that it can wait for
namespace creation and removal. Call nvmf_wait_for_ns() for removal
after _remove_nvmet_ns() call. While at it, reduce the wait time unit
from 1 second to 0.1 second to shorten test time.

The test case intends to catch the regression fixed by the kernel commit
ff0ffe5b7c3c ("nvme: fix namespace removal list"). I reverted the commit
from the kernel v6.11-rc4, then confirmed that the test case still can
catch the regression with this change.

Link: https://lore.kernel.org/linux-block/tczctp5tkr34o3k3f4dlyhuutgp2ycex6gdbjuqx4trn6ewm2i@qbkza3yr5wdd/
Fixes: 077211a ("nvme: add test for creating/deleting file-ns")
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>

tests/nvme/052

@@ -20,23 +20,27 @@ set_conditions() {
 	_set_nvme_trtype "$@"
 }
 
+# Wait for the namespace with specified uuid to fulfill the specified condtion,
+# "created" or "removed".
 nvmf_wait_for_ns() {
 	local ns
 	local timeout="5"
 	local uuid="$1"
+	local condition="$2"
 
-	ns=$(_find_nvme_ns "${uuid}")
+	ns=$(_find_nvme_ns "${uuid}" 2>> "$FULL")
 
 	start_time=$(date +%s)
-	while [[ -z "$ns" ]]; do
-		sleep 1
+	while [[ -z "$ns" && "$condition" == created ]] ||
+		      [[ -n "$ns" && "$condition" == removed ]]; do
+		sleep .1
 		end_time=$(date +%s)
 		if (( end_time - start_time > timeout )); then
 			echo "namespace with uuid \"${uuid}\" not " \
-				"found within ${timeout} seconds"
+				"${condition} within ${timeout} seconds"
 			return 1
 		fi
-		ns=$(_find_nvme_ns "${uuid}")
+		ns=$(_find_nvme_ns "${uuid}" 2>> "$FULL")
 	done
 
 	return 0
@@ -63,14 +67,21 @@ test() {
 		_create_nvmet_ns "${def_subsysnqn}" "${i}" "$(_nvme_def_file_path).$i" "${uuid}"
 
 		# wait until async request is processed and ns is created
-		nvmf_wait_for_ns "${uuid}"
-		if [ $? -eq 1 ]; then
+		if ! nvmf_wait_for_ns "${uuid}" created; then
 			echo "FAIL"
 			rm "$(_nvme_def_file_path).$i"
 			break
 		fi
 
 		_remove_nvmet_ns "${def_subsysnqn}" "${i}"
+
+		# wait until async request is processed and ns is removed
+		if ! nvmf_wait_for_ns "${uuid}" removed; then
+			echo "FAIL"
+			rm "$(_nvme_def_file_path).$i"
+			break
+		fi
+
 		rm "$(_nvme_def_file_path).$i"
 	}
 	done