[PATCH blktests] nvme/052: wait for namespace removal before recreating namespace

[Shin'ichiro Kawasaki]

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. For this purpose, add the new helper function
nvmf_wait_for_ns_removal(). To specify the namespace to wait for, get
the name of the namespace from nvmf_wait_for_ns(), and pass it to
nvmf_wait_for_ns_removal().

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: 077211a0e9ff ("nvme: add test for creating/deleting file-ns")
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki at wdc.com>
---
Nelay, Yi, thank you for the feedbacks for the discussion
thread at the Link. Here's the formal fix patch.

 tests/nvme/052 | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/tests/nvme/052 b/tests/nvme/052
index cf6061a..e1ac823 100755
--- a/tests/nvme/052
+++ b/tests/nvme/052
@@ -39,15 +39,32 @@ nvmf_wait_for_ns() {
 		ns=$(_find_nvme_ns "${uuid}")
 	done
 
+	echo "$ns"
 	return 0
 }
 
+nvmf_wait_for_ns_removal() {
+	local ns=$1 i
+
+	for ((i = 0; i < 10; i++)); do
+		if [[ ! -e /dev/$ns ]]; then
+			return
+		fi
+		sleep .1
+		echo "wait removal of $ns" >> "$FULL"
+	done
+
+	if [[ -e /dev/$ns ]]; then
+		echo "Failed to remove the namespace $ns"
+	fi
+}
+
 test() {
 	echo "Running ${TEST_NAME}"
 
 	_setup_nvmet
 
-	local iterations=20
+	local iterations=20 ns
 
 	_nvmet_target_setup
 
@@ -63,7 +80,7 @@ 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 "${uuid}"
+		ns=$(nvmf_wait_for_ns "${uuid}")
 		if [ $? -eq 1 ]; then
 			echo "FAIL"
 			rm "$(_nvme_def_file_path).$i"
@@ -71,6 +88,7 @@ test() {
 		fi
 
 		_remove_nvmet_ns "${def_subsysnqn}" "${i}"
+		nvmf_wait_for_ns_removal "$ns"
 		rm "$(_nvme_def_file_path).$i"
 	}
 	done
-- 
2.45.2