[LTP] [PATCH] fanotify10, fanotify23: fix cleanup of vfs_cache_pressure

[Amir Goldstein]

Avoid setting vfs_cache_pressure to zero if test was not run
because kernel does not support fanotify.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/linux-fsdevel/20250622215140.GX1880847@ZenIV/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 testcases/kernel/syscalls/fanotify/fanotify10.c | 8 ++++----
 testcases/kernel/syscalls/fanotify/fanotify23.c | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/testcases/kernel/syscalls/fanotify/fanotify10.c b/testcases/kernel/syscalls/fanotify/fanotify10.c
index ccb4f55df..2d33416f3 100644
--- a/testcases/kernel/syscalls/fanotify/fanotify10.c
+++ b/testcases/kernel/syscalls/fanotify/fanotify10.c
@@ -102,7 +102,6 @@ static int ignore_mark_unsupported;
 #define DROP_CACHES_FILE "/proc/sys/vm/drop_caches"
 #define CACHE_PRESSURE_FILE "/proc/sys/vm/vfs_cache_pressure"
 
-static int old_cache_pressure;
 static pid_t child_pid;
 static int bind_mount_created;
 static unsigned int num_classes = NUM_CLASSES;
@@ -925,7 +924,6 @@ static void setup(void)
 	SAFE_MKDIR(MNT2_PATH, 0755);
 	mount_cycle();
 
-	SAFE_FILE_SCANF(CACHE_PRESSURE_FILE, "%d", &old_cache_pressure);
 	/* Set high priority for evicting inodes */
 	SAFE_FILE_PRINTF(CACHE_PRESSURE_FILE, "500");
 }
@@ -939,8 +937,6 @@ static void cleanup(void)
 	if (bind_mount_created)
 		SAFE_UMOUNT(MNT2_PATH);
 
-	SAFE_FILE_PRINTF(CACHE_PRESSURE_FILE, "%d", old_cache_pressure);
-
 	for (i = 0; i < max_file_multi; i++) {
 		char path[PATH_MAX];
 
@@ -972,6 +968,10 @@ static struct tst_test test = {
 		TEST_APP,
 		NULL
 	},
+	.save_restore = (const struct tst_path_val[]) {
+		{CACHE_PRESSURE_FILE, NULL, TST_SR_TCONF},
+		{}
+	},
 	.tags = (const struct tst_tag[]) {
 		{"linux-git", "9bdda4e9cf2d"},
 		{"linux-git", "2f02fd3fa13e"},
diff --git a/testcases/kernel/syscalls/fanotify/fanotify23.c b/testcases/kernel/syscalls/fanotify/fanotify23.c
index 26c9e87fb..36c7779da 100644
--- a/testcases/kernel/syscalls/fanotify/fanotify23.c
+++ b/testcases/kernel/syscalls/fanotify/fanotify23.c
@@ -35,7 +35,6 @@
 #define DROP_CACHES_FILE "/proc/sys/vm/drop_caches"
 #define CACHE_PRESSURE_FILE "/proc/sys/vm/vfs_cache_pressure"
 
-static int old_cache_pressure;
 static int fd_notify;
 
 static unsigned long long event_set[EVENT_MAX];
@@ -234,7 +233,6 @@ static void setup(void)
 						FAN_MARK_FILESYSTEM,
 						FAN_ATTRIB, MOUNT_PATH);
 
-	SAFE_FILE_SCANF(CACHE_PRESSURE_FILE, "%d", &old_cache_pressure);
 	/* Set high priority for evicting inodes */
 	SAFE_FILE_PRINTF(CACHE_PRESSURE_FILE, "500");
 }
@@ -243,8 +241,6 @@ static void cleanup(void)
 {
 	if (fd_notify > 0)
 		SAFE_CLOSE(fd_notify);
-
-	SAFE_FILE_PRINTF(CACHE_PRESSURE_FILE, "%d", old_cache_pressure);
 }
 
 static struct tst_test test = {
@@ -259,6 +255,10 @@ static struct tst_test test = {
 		{.type = "ext2"},
 		{}
 	},
+	.save_restore = (const struct tst_path_val[]) {
+		{CACHE_PRESSURE_FILE, NULL, TST_SR_TCONF},
+		{}
+	},
 };
 
 #else
-- 
2.43.0