Re: [LTP] [PATCH 2/2] fanotify13: Test watching overlayfs with FAN_REPORT_FID

[Petr Vorel <pvorel@suse.cz>]

Hi Amir,

Reviewed-by: Petr Vorel <pvorel@suse.cz>
Few notes below.

> Run test variants watching overlayfs (over all supported fs)
> and reporting events with fid.

> This requires overlayfs support for AT_HANDLE_FID (kernel 6.6) and
> even with AT_HANDLE_FID file handles, only inode marks are supported.

> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> ---
>  testcases/kernel/syscalls/fanotify/fanotify.h | 28 ++++++++++++-----
>  .../kernel/syscalls/fanotify/fanotify13.c     | 31 ++++++++++++++++---
>  2 files changed, 47 insertions(+), 12 deletions(-)

> diff --git a/testcases/kernel/syscalls/fanotify/fanotify.h b/testcases/kernel/syscalls/fanotify/fanotify.h
> index 78424a350..a8aec6597 100644
> --- a/testcases/kernel/syscalls/fanotify/fanotify.h
> +++ b/testcases/kernel/syscalls/fanotify/fanotify.h
> @@ -79,8 +79,11 @@ static inline int safe_fanotify_mark(const char *file, const int lineno,
>  /*
>   * Helper function used to obtain fsid and file_handle for a given path.
>   * Used by test files correlated to FAN_REPORT_FID functionality.
> + *
> + * Returns 0 if normal NFS file handles are supported.
> + * Returns AT_HANDLE_FID, of only non-decodeable file handles are supported.
s/ of / if /
I can fix this before merge.

Also I noticed (not related to this change) that #define AT_HANDLE_FID 0x200
added in dc7b1332ab into testcases/kernel/syscalls/fanotify/fanotify.h should
have been in include/lapi/fanotify.h (this file is for fallback definitions).
Tiny detail, which should be fixed afterwards.

>   */
> -static inline void fanotify_get_fid(const char *path, __kernel_fsid_t *fsid,
> +static inline int fanotify_get_fid(const char *path, __kernel_fsid_t *fsid,
>  				    struct file_handle *handle)
>  {
>  	int mount_id;
> @@ -93,6 +96,11 @@ static inline void fanotify_get_fid(const char *path, __kernel_fsid_t *fsid,

>  	if (name_to_handle_at(AT_FDCWD, path, handle, &mount_id, 0) == -1) {
>  		if (errno == EOPNOTSUPP) {
> +			/* Try to request non-decodeable fid instead */
> +			if (name_to_handle_at(AT_FDCWD, path, handle, &mount_id,
> +					      AT_HANDLE_FID) == 0)
> +				return AT_HANDLE_FID;
> +
>  			tst_brk(TCONF,
>  				"filesystem %s does not support file handles",
>  				tst_device->fs_type);
> @@ -100,6 +108,7 @@ static inline void fanotify_get_fid(const char *path, __kernel_fsid_t *fsid,
>  		tst_brk(TBROK | TERRNO,
>  			"name_to_handle_at(AT_FDCWD, %s, ...) failed", path);
>  	}
> +	return 0;
>  }

>  #ifndef FILEID_INVALID
> @@ -112,18 +121,21 @@ struct fanotify_fid_t {
>  	char buf[MAX_HANDLE_SZ];
>  };

> -static inline void fanotify_save_fid(const char *path,
> +static inline int fanotify_save_fid(const char *path,
>  				     struct fanotify_fid_t *fid)
>  {
>  	int *fh = (int *)(fid->handle.f_handle);
> +	int ret;

>  	fh[0] = fh[1] = fh[2] = 0;
>  	fid->handle.handle_bytes = MAX_HANDLE_SZ;
> -	fanotify_get_fid(path, &fid->fsid, &fid->handle);
> +	ret = fanotify_get_fid(path, &fid->fsid, &fid->handle);

>  	tst_res(TINFO,
>  		"fid(%s) = %x.%x.%x.%x.%x...", path, fid->fsid.val[0],
>  		fid->fsid.val[1], fh[0], fh[1], fh[2]);
> +
> +	return ret;
>  }
>  #endif /* HAVE_NAME_TO_HANDLE_AT */

> @@ -179,6 +191,7 @@ static inline int fanotify_events_supported_by_kernel(uint64_t mask,
>   * @return  0: fanotify supported both in kernel and on tested filesystem
>   * @return -1: @flags not supported in kernel
>   * @return -2: @flags not supported on tested filesystem (tested if @fname is not NULL)
> + * @return -3: @flags not supported on overlayfs (tested if @fname == OVL_MNT)
>   */
>  static inline int fanotify_init_flags_supported_on_fs(unsigned int flags, const char *fname)
>  {
> @@ -199,7 +212,7 @@ static inline int fanotify_init_flags_supported_on_fs(unsigned int flags, const

>  	if (fname && fanotify_mark(fd, FAN_MARK_ADD, FAN_ACCESS, AT_FDCWD, fname) < 0) {
>  		if (errno == ENODEV || errno == EOPNOTSUPP || errno == EXDEV) {
> -			rval = -2;
> +			rval = strcmp(fname, OVL_MNT) ? -2 : -3;
>  		} else {
>  			tst_brk(TBROK | TERRNO,
>  				"fanotify_mark (%d, FAN_MARK_ADD, ..., AT_FDCWD, %s) failed",
> @@ -269,10 +282,11 @@ static inline void fanotify_init_flags_err_msg(const char *flags_str,
>  	if (fail == -1)
>  		res_func(file, lineno, TCONF,
>  			 "%s not supported in kernel?", flags_str);
> -	if (fail == -2)
> +	if (fail == -2 || fail == -3)
>  		res_func(file, lineno, TCONF,
> -			 "%s not supported on %s filesystem",
> -			 flags_str, tst_device->fs_type);
> +			 "%s not supported on %s%s filesystem",
> +			 flags_str, fail == -3 ? "overlayfs over " : "",
> +			 tst_device->fs_type);
>  }

>  #define FANOTIFY_INIT_FLAGS_ERR_MSG(flags, fail) \
> diff --git a/testcases/kernel/syscalls/fanotify/fanotify13.c b/testcases/kernel/syscalls/fanotify/fanotify13.c
> index 4bcffaab2..4a7c2af23 100644
> --- a/testcases/kernel/syscalls/fanotify/fanotify13.c
> +++ b/testcases/kernel/syscalls/fanotify/fanotify13.c
> @@ -91,8 +91,10 @@ static struct test_case_t {

>  static int ovl_mounted;
>  static int bind_mounted;
> +static int ovl_bind_mounted;
>  static int nofid_fd;
>  static int fanotify_fd;
> +static int at_handle_fid;
>  static int filesystem_mark_unsupported;
>  static char events_buf[BUF_SIZE];
>  static struct event_t event_set[EVENT_MAX];
> @@ -113,8 +115,10 @@ static void get_object_stats(void)
>  {
>  	unsigned int i;

> -	for (i = 0; i < ARRAY_SIZE(objects); i++)
> -		fanotify_save_fid(objects[i].path, &objects[i].fid);
> +	for (i = 0; i < ARRAY_SIZE(objects); i++) {
> +		at_handle_fid |=
> +			fanotify_save_fid(objects[i].path, &objects[i].fid);
> +	}
>  }

>  static int setup_marks(unsigned int fd, struct test_case_t *tc)
> @@ -154,6 +158,11 @@ static void do_test(unsigned int number)
>  		return;
>  	}

> +	if (at_handle_fid && mark->flag != FAN_MARK_INODE) {
> +		tst_res(TCONF, "overlayfs does not support decodeable file handles required by %s", mark->name);
> +		return;
> +	}
> +
>  	if (filesystem_mark_unsupported && mark->flag & FAN_MARK_FILESYSTEM) {
>  		tst_res(TCONF, "FAN_MARK_FILESYSTEM not supported in kernel?");
>  		return;
> @@ -169,7 +178,7 @@ static void do_test(unsigned int number)
>  		goto out;

>  	/* Watching base fs - open files on overlayfs */
> -	if (tst_variant) {
> +	if (tst_variant && !ovl_bind_mounted) {
>  		if (mark->flag & FAN_MARK_MOUNT) {
>  			tst_res(TCONF, "overlayfs base fs cannot be watched with mount mark");
>  			goto out;
> @@ -191,7 +200,7 @@ static void do_test(unsigned int number)
>  			SAFE_CLOSE(fds[i]);
>  	}

> -	if (tst_variant)
> +	if (tst_variant && !ovl_bind_mounted)
>  		SAFE_UMOUNT(MOUNT_PATH);

>  	/* Read events from event queue */
> @@ -288,6 +297,8 @@ static void do_setup(void)
>  	 * Variant #0: watch base fs - open files on base fs
>  	 * Variant #1: watch lower fs - open lower files on overlayfs
>  	 * Variant #2: watch upper fs - open upper files on overlayfs
> +	 * Variant #3: watch overlayfs - open lower files on overlayfs
> +	 * Variant #4: watch overlayfs - open upper files on overlayfs
>  	 *
>  	 * Variants 1,2 test a bug whose fix bc2473c90fca ("ovl: enable fsnotify
>  	 * events on underlying real files") in kernel 6.5 is not likely to be
> @@ -295,6 +306,8 @@ static void do_setup(void)
>  	 * To avoid waiting for events that won't arrive when testing old kernels,
>  	 * require that kernel supports encoding fid with new flag AT_HADNLE_FID,
s/AT_HADNLE_FID/AT_HANDLE_FID/
(old typo)

>  	 * also merged to 6.5 and not likely to be backported to older kernels.
> +	 * Variants 3,4 test overlayfs watch with FAN_REPORT_FID, which also
> +	 * requires kernel with support for AT_HADNLE_FID.
s/AT_HADNLE_FID/AT_HANDLE_FID/
(new typo)
I can fix these during merge.

Kind regards,
Petr

>  	 */
>  	if (tst_variant) {
>  		REQUIRE_HANDLE_TYPE_SUPPORTED_BY_KERNEL(AT_HANDLE_FID);
> @@ -319,6 +332,12 @@ static void do_setup(void)
>  	/* Create file and directory objects for testing on base fs */
>  	create_objects();

> +	if (tst_variant > 2) {
> +		/* Setup watches on overlayfs */
> +		SAFE_MOUNT(OVL_MNT, MOUNT_PATH, "none", MS_BIND, NULL);
> +		ovl_bind_mounted = 1;
> +	}
> +
>  	/*
>  	 * Create a mark on first inode without FAN_REPORT_FID, to test
>  	 * uninitialized connector->fsid cache. This mark remains for all test
> @@ -337,6 +356,8 @@ static void do_cleanup(void)
>  		SAFE_CLOSE(nofid_fd);
>  	if (fanotify_fd > 0)
>  		SAFE_CLOSE(fanotify_fd);
> +	if (ovl_bind_mounted)
> +		SAFE_UMOUNT(MOUNT_PATH);
>  	if (bind_mounted) {
>  		SAFE_UMOUNT(MOUNT_PATH);
>  		SAFE_RMDIR(MOUNT_PATH);
> @@ -348,7 +369,7 @@ static void do_cleanup(void)
>  static struct tst_test test = {
>  	.test = do_test,
>  	.tcnt = ARRAY_SIZE(test_cases),
> -	.test_variants = 3,
> +	.test_variants = 5,
>  	.setup = do_setup,
>  	.cleanup = do_cleanup,
>  	.needs_root = 1,

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