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

[Amir Goldstein]

On Tue, Jun 24, 2025 at 6:39 AM Wei Gao <wegao@suse.com> wrote:
>
> On Mon, Jun 23, 2025 at 09:37:17AM +0200, Amir Goldstein wrote:
> > 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
>
> For me this patch more looks like an improvement instead of a fix.
> Thanks for your patch.
>

It is a fix to the problem reported by Al Viro in the linked message.

Thanks,
Amir.