Re: [LTP] [PATCH 3/3] fanotify24: add mmap() and user page fault to test

[Petr Vorel <pvorel@suse.cz>]

Hi Amir,

> Commit 066e053fe208a ("fsnotify: add pre-content hooks on mmap()")
> in 6.14-rc7 added a pre-content hooh in mmap() before the final release
> of the fsnotify pre-content event feature.

> To test pre-content hook on mmap(), increase the size of the test file
> to 101 pages use mmap() to setup a buffer from the end of the test file.

> Change some of the test cases to allow the write() and use this buffer
> as the input buffer to write(), which tests deadlock avoidance by
> suppresing pre-content hook on user page faults.

> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> ---
>  .../kernel/syscalls/fanotify/fanotify24.c     | 41 ++++++++++++++++---
>  1 file changed, 35 insertions(+), 6 deletions(-)

> diff --git a/testcases/kernel/syscalls/fanotify/fanotify24.c b/testcases/kernel/syscalls/fanotify/fanotify24.c
> index 2d2479b39..3a76f2c1b 100644
> --- a/testcases/kernel/syscalls/fanotify/fanotify24.c
> +++ b/testcases/kernel/syscalls/fanotify/fanotify24.c
> @@ -46,6 +46,7 @@
>  static char fname[BUF_SIZE];
>  static char buf[BUF_SIZE];
>  static volatile int fd_notify;
> +static size_t page_sz;

>  static pid_t child_pid;

> @@ -68,7 +69,8 @@ static struct tcase {
>  		FAN_OPEN_PERM | FAN_PRE_ACCESS,
>  		{
>  			{FAN_OPEN_PERM, FAN_ALLOW},
> -			{FAN_PRE_ACCESS, FAN_DENY},
> +			{FAN_PRE_ACCESS, FAN_ALLOW},
> +			{FAN_PRE_ACCESS, FAN_ALLOW},

If I understand correctly, these doubled FAN_PRE_ACCESS, FAN_ALLOW are for
reusing the write buffer, right? Obviously it's needed but on the first look it
looks like error.

<snip>

Kind regards,
Petr

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