OVL_MNT: put overlayfs lower, upper, work, mnt dir in separated mountpoint

Some tests are mounting overlayfs internally and run tests on it. This mount can fail if the filesystem we are running on does not support overlay mount upon it. For example, we are already running tests on overlayfs or NFS, or CIFS. Test will report broken and failure.

Fixing this by put overlayfs dirs in a separaed mountpoint, like readahead02 by Amir.

Signed-off-by Xiong Zhou <[email protected]>

 testcases/kernel/syscalls/inotify/inotify07.c | 24 +++++++++++------

testcases/kernel/syscalls/execveat/execveat03.c +8 -1

-#define OVL_MNT "ovl"
+#define MNTPOINT	"mntpoint"
+#define OVL_LOWER	MNTPOINT"/lower"
+#define OVL_UPPER	MNTPOINT"/upper"
+#define OVL_WORK	MNTPOINT"/work"
+#define OVL_MNT		MNTPOINT"/ovl"
+
 #define TEST_APP "execveat_child"
 #define TEST_FILE_PATH OVL_MNT"/"TEST_APP
 
+static const char mntpoint[] = MNTPOINT;
+
 static int ovl_mounted;
 
 static void do_child(void)

--- a/testcases/kernel/syscalls/execveat/execveat03.c

testcases/kernel/syscalls/execveat/execveat03.c +0 -7

-	/* Setup an overlay mount with lower file */
-	SAFE_MKDIR("lower", 0755);
-	SAFE_MKDIR("upper", 0755);
-	SAFE_MKDIR("work", 0755);
-	SAFE_MKDIR(OVL_MNT, 0755);
-	ret = mount("overlay", OVL_MNT, "overlay", 0,
-		    "lowerdir=lower,upperdir=upper,workdir=work");

Hi Murphy,

Quoted 1 line

--- a/testcases/kernel/syscalls/execveat/execveat03.c

...

Quoted 10 lines

testcases/kernel/syscalls/execveat/execveat03.c +0 -10

-	/* Setup an overlay mount with lower file */
-	SAFE_MKDIR("lower", 0755);
-	SAFE_MKDIR("upper", 0755);
-	SAFE_MKDIR("work", 0755);
-	SAFE_MKDIR(OVL_MNT, 0755);
-	ret = mount("overlay", OVL_MNT, "overlay", 0,
-		    "lowerdir=lower,upperdir=upper,workdir=work");
-	if (ret < 0) {
-		if (errno == ENODEV) {
-			tst_brk(TCONF,

testcases/kernel/syscalls/execveat/execveat03.c static void verify_execveat(void) · line 93

Quoted 7 lines

testcases/kernel/syscalls/execveat/execveat03.c +2 -5

-				"overlayfs is not configured in this kernel.");
-		}
-		tst_brk(TBROK | TERRNO, "overlayfs mount failed");
-	}
-	ovl_mounted = 1;
+	if (setup_overlay(1) == 0)
+		ovl_mounted = 1;

Here you change test behavior on ENODEV.

+ more info at 1st patch.

Kind regards,
Petr

To create overlayfs dirs, and mount overlayfs if needed.

...

lib/tst_fs_setup.c line 29

Quoted 13 lines

lib/tst_fs_setup.c new file +13 -0

+int setup_overlay(int mountovl)
+{
+	int ret;
+
+	/* Setup an overlay mount with lower dir and file */
+	SAFE_MKDIR(OVL_LOWER, 0755);
+	SAFE_MKDIR(OVL_UPPER, 0755);
+	SAFE_MKDIR(OVL_WORK, 0755);
+	SAFE_MKDIR(OVL_MNT, 0755);
+
+	/* Only create dirs, do not mount */
+	if (mountovl == 0)
+		return 0;

Instead of having int parameter, there could be create_overlay_dirs() and mount_overlay(), which would call create_overlay_dirs(). (no need to lookup meaning of parameter).

lib/tst_fs_setup.c line 37

Quoted 8 lines

lib/tst_fs_setup.c new file +8 -0

+
+	ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
+		    ",upperdir="OVL_UPPER",workdir="OVL_WORK);
+	if (ret < 0) {
+		if (errno == ENODEV) {
+			tst_res(TINFO,
+				"overlayfs is not configured in this kernel.");
+			return 1;

First I thought we'd implement it as a test flag (member of struct tst_test). When we have it as separate function I wonder whether we could TCONF on ENODEV instead of TINFO and return. Maybe there could be here for int strict parameter, where 1 would be force safe (i.e. TCONF), otherwise only TINFO.
This could also to have SAFE_MOUNT_OVERLAY() macro which would use mount_overlay(). Similar approach as SAFE_SEND() and safe_send().

+++ b/testcases/kernel/syscalls/inotify/inotify07.c

(quoted diff) +1 -7

-#define OVL_MNT "ovl"
 #define DIR_NAME "test_dir"
 #define DIR_PATH OVL_MNT"/"DIR_NAME
 #define FILE_NAME "test_file"
 #define FILE_PATH OVL_MNT"/"DIR_NAME"/"FILE_NAME
 
 static int ovl_mounted;
+static const char mntpoint[] = OVL_BASE_MNTPOINT;
 
 static struct event_t event_set[EVENT_MAX];

@@ -164,14 +164,11 @@ static void setup(void)
 	int ret;
 
 	/* Setup an overlay mount with lower dir and file */
-	SAFE_MKDIR("lower", 0755);
-	SAFE_MKDIR("lower/"DIR_NAME, 0755);
-	SAFE_TOUCH("lower/"DIR_NAME"/"FILE_NAME, 0644, NULL);
-	SAFE_MKDIR("upper", 0755);
-	SAFE_MKDIR("work", 0755);
-	SAFE_MKDIR(OVL_MNT, 0755);

Hi Murphy,

Quoted 26 lines

...

lib/tst_fs_setup.c line 29

Quoted 13 lines

lib/tst_fs_setup.c new file +13 -0

+int setup_overlay(int mountovl)
+{
+   int ret;
+
+   /* Setup an overlay mount with lower dir and file */
+   SAFE_MKDIR(OVL_LOWER, 0755);
+   SAFE_MKDIR(OVL_UPPER, 0755);
+   SAFE_MKDIR(OVL_WORK, 0755);
+   SAFE_MKDIR(OVL_MNT, 0755);
+
+   /* Only create dirs, do not mount */
+   if (mountovl == 0)
+           return 0;

Instead of having int parameter, there could be create_overlay_dirs() and mount_overlay(), which would call create_overlay_dirs(). (no need to lookup meaning of parameter).

lib/tst_fs_setup.c line 37

Quoted 8 lines

lib/tst_fs_setup.c new file +8 -0

+
+   ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
+               ",upperdir="OVL_UPPER",workdir="OVL_WORK);
+   if (ret < 0) {
+           if (errno == ENODEV) {
+                   tst_res(TINFO,
+                           "overlayfs is not configured in this kernel.");
+                   return 1;

Quoted 6 lines

First I thought we'd implement it as a test flag (member of struct tst_test). When we have it as separate function I wonder whether we could TCONF on ENODEV instead of TINFO and return. Maybe there could be here for int strict parameter, where 1 would be force safe (i.e. TCONF), otherwise only TINFO.
This could also to have SAFE_MOUNT_OVERLAY() macro which would use mount_overlay(). Similar approach as SAFE_SEND() and safe_send().

From next patch:

Quoted 22 lines

+++ b/testcases/kernel/syscalls/inotify/inotify07.c

(quoted diff) +1 -7

-#define OVL_MNT "ovl"
 #define DIR_NAME "test_dir"
 #define DIR_PATH OVL_MNT"/"DIR_NAME
 #define FILE_NAME "test_file"
 #define FILE_PATH OVL_MNT"/"DIR_NAME"/"FILE_NAME
 
 static int ovl_mounted;
+static const char mntpoint[] = OVL_BASE_MNTPOINT;
 
 static struct event_t event_set[EVENT_MAX];

@@ -164,14 +164,11 @@ static void setup(void)
      int ret;
 
      /* Setup an overlay mount with lower dir and file */
-     SAFE_MKDIR("lower", 0755);
-     SAFE_MKDIR("lower/"DIR_NAME, 0755);
-     SAFE_TOUCH("lower/"DIR_NAME"/"FILE_NAME, 0644, NULL);
-     SAFE_MKDIR("upper", 0755);
-     SAFE_MKDIR("work", 0755);
-     SAFE_MKDIR(OVL_MNT, 0755);

Review static void setup(void) · line 174

Quoted 10 lines

(quoted diff) +5 -2

-     ret = mount("overlay", OVL_MNT, "overlay", 0,
-                 "lowerdir=lower,upperdir=upper,workdir=work");
+     setup_overlay(0);
+     SAFE_MKDIR(OVL_LOWER"/"DIR_NAME, 0755);
+     SAFE_TOUCH(OVL_LOWER"/"DIR_NAME"/"FILE_NAME, 0644, NULL);
+     ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
+                 ",upperdir="OVL_UPPER",workdir="OVL_WORK);
      if (ret < 0) {
              if (errno == ENODEV) {
                      tst_brk(TCONF,

In here in inotify07.c and in inotify08.c you create dirs (0 parameter) for because you it's needed to create more dirs. Than the rest (mount, TCONF on ENODEV, TBROK otherwise) is still copy pasted. I wonder how to move everything into setup_overlay() helper. Maybe struct with files or directories and permissions to for touch/mkdir? With this, int mountovl dir create_overlay_dirs() might not be needed.

I liked your idea of create_overlay_dirs/mount_overlay better. It is more flexible for future tests that may want to umount and mount overlay several times and the setup of lower/upper files could be very different in future tests, not limited to just creating files (maybe symlinks, xattr).
The experience from xfstests overlay tests suggests that the create_overlay_dirs/mount_overlay helpers are a good model to follow.

Thanks,
Amir.

Hi Amir, Murphy,

Quoted 7 lines

I liked your idea of create_overlay_dirs/mount_overlay better. It is more flexible for future tests that may want to umount and mount overlay several times and the setup of lower/upper files could be very different in future tests, not limited to just creating files (maybe symlinks, xattr).
The experience from xfstests overlay tests suggests that the create_overlay_dirs/mount_overlay helpers are a good model to follow.

Thanks for ideas, agree with it.

Other thing is to have const char *file, const int lineno as first parameters for mount_overlay_() and create mount_overlay() and SAFE_MOUNT_OVERLAY() as macros, which would use it. See tst_mkfs{_,}() as examples.

Quoted 3 lines

Thanks,
Amir.

Kind regards,
Petr

Hi Murphy,

Quoted 18 lines

...

lib/tst_fs_setup.c line 29

Quoted 13 lines

lib/tst_fs_setup.c new file +13 -0

+int setup_overlay(int mountovl)
+{
+	int ret;
+
+	/* Setup an overlay mount with lower dir and file */
+	SAFE_MKDIR(OVL_LOWER, 0755);
+	SAFE_MKDIR(OVL_UPPER, 0755);
+	SAFE_MKDIR(OVL_WORK, 0755);
+	SAFE_MKDIR(OVL_MNT, 0755);
+
+	/* Only create dirs, do not mount */
+	if (mountovl == 0)
+		return 0;

Instead of having int parameter, there could be create_overlay_dirs() and mount_overlay(), which would call create_overlay_dirs(). (no need to lookup meaning of parameter).

Quoted 14 lines

lib/tst_fs_setup.c line 37

Quoted 8 lines

lib/tst_fs_setup.c new file +8 -0

+
+	ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
+		    ",upperdir="OVL_UPPER",workdir="OVL_WORK);
+	if (ret < 0) {
+		if (errno == ENODEV) {
+			tst_res(TINFO,
+				"overlayfs is not configured in this kernel.");
+			return 1;

First I thought we'd implement it as a test flag (member of struct tst_test). When we have it as separate function I wonder whether we could TCONF on ENODEV instead of TINFO and return. Maybe there could be here for int strict parameter, where 1 would be force safe (i.e. TCONF), otherwise only TINFO.
This could also to have SAFE_MOUNT_OVERLAY() macro which would use mount_overlay(). Similar approach as SAFE_SEND() and safe_send().

From next patch:

Quoted 28 lines

+++ b/testcases/kernel/syscalls/inotify/inotify07.c

(quoted diff) +5 -9

-#define OVL_MNT "ovl"
 #define DIR_NAME "test_dir"
 #define DIR_PATH OVL_MNT"/"DIR_NAME
 #define FILE_NAME "test_file"
 #define FILE_PATH OVL_MNT"/"DIR_NAME"/"FILE_NAME
 
 static int ovl_mounted;
+static const char mntpoint[] = OVL_BASE_MNTPOINT;
 
 static struct event_t event_set[EVENT_MAX];

@@ -164,14 +164,11 @@ static void setup(void)
 	int ret;
 
 	/* Setup an overlay mount with lower dir and file */
-	SAFE_MKDIR("lower", 0755);
-	SAFE_MKDIR("lower/"DIR_NAME, 0755);
-	SAFE_TOUCH("lower/"DIR_NAME"/"FILE_NAME, 0644, NULL);
-	SAFE_MKDIR("upper", 0755);
-	SAFE_MKDIR("work", 0755);
-	SAFE_MKDIR(OVL_MNT, 0755);
-	ret = mount("overlay", OVL_MNT, "overlay", 0,
-		    "lowerdir=lower,upperdir=upper,workdir=work");
+	setup_overlay(0);
+	SAFE_MKDIR(OVL_LOWER"/"DIR_NAME, 0755);
+	SAFE_TOUCH(OVL_LOWER"/"DIR_NAME"/"FILE_NAME, 0644, NULL);
+	ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER

Review static void setup(void) · line 174

Quoted 4 lines

(quoted diff) +1 -0

+		    ",upperdir="OVL_UPPER",workdir="OVL_WORK);
 	if (ret < 0) {
 		if (errno == ENODEV) {
 			tst_brk(TCONF,

In here in inotify07.c and in inotify08.c you create dirs (0 parameter) for because you it's needed to create more dirs. Than the rest (mount, TCONF on ENODEV, TBROK otherwise) is still copy pasted. I wonder how to move everything into setup_overlay() helper. Maybe struct with files or directories and permissions

to for touch/mkdir? With this, int mountovl dir create_overlay_dirs() might not be needed.

Kind regards,
Petr

Quoted 11 lines

Review

Quoted 7 lines

(quoted diff) +4 -0

+	SAFE_MKDIR(OVL_LOWER"/"DIR_NAME, 0755);
+	SAFE_TOUCH(OVL_LOWER"/"DIR_NAME"/"FILE_NAME, 0644, NULL);
+	ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
+		    ",upperdir="OVL_UPPER",workdir="OVL_WORK);
 	if (ret < 0) {
 		if (errno == ENODEV) {
 			tst_brk(TCONF,

In here in inotify07.c and in inotify08.c you create dirs (0 parameter) for because you it's needed to create more dirs. Than the rest (mount, TCONF on ENODEV, TBROK otherwise) is still copy pasted. I wonder how to move everything into setup_overlay() helper. Maybe struct with files or directories and permissions

If we define a struct to put names amd modes in it then pass to helper, we still need to write all these OVL macros in the testcase to defile the struct. So we need to write all the _same_ macros in every testcase where needed.

In this case, it's against my intention of this patch: dedupe duplicated lines.

Your struct idea is great when handling the different files that need to be created in different testcases. However I'd like to do it in a simpler way. Only make necessary dirs in the helper, let the testcases to create the other dirs they want themselves.

Thanks,
Murphy

Hi Murphy,

Quoted 1 line

To create overlayfs dirs, and mount overlayfs if needed.

...

lib/tst_fs_setup.c line 29

Quoted 13 lines

lib/tst_fs_setup.c new file +13 -0

+int setup_overlay(int mountovl)
+{
+	int ret;
+
+	/* Setup an overlay mount with lower dir and file */
+	SAFE_MKDIR(OVL_LOWER, 0755);
+	SAFE_MKDIR(OVL_UPPER, 0755);
+	SAFE_MKDIR(OVL_WORK, 0755);
+	SAFE_MKDIR(OVL_MNT, 0755);
+
+	/* Only create dirs, do not mount */
+	if (mountovl == 0)
+		return 0;

Instead of having int parameter, there could be create_overlay_dirs() and mount_overlay(), which would call create_overlay_dirs(). (no need to lookup meaning of parameter).

lib/tst_fs_setup.c line 37

Quoted 8 lines

lib/tst_fs_setup.c new file +8 -0

+
+	ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
+		    ",upperdir="OVL_UPPER",workdir="OVL_WORK);
+	if (ret < 0) {
+		if (errno == ENODEV) {
+			tst_res(TINFO,
+				"overlayfs is not configured in this kernel.");
+			return 1;

First I thought we'd implement it as a test flag (member of struct tst_test). When we have it as separate function I wonder whether we could TCONF on ENODEV instead of TINFO and return. Maybe there could be here for int strict parameter,

where 1 would be force safe (i.e. TCONF), otherwise only TINFO.
This could also to have SAFE_MOUNT_OVERLAY() macro which would use mount_overlay(). Similar approach as SAFE_SEND() and safe_send().

lib/tst_fs_setup.c line 42

Quoted 5 lines

lib/tst_fs_setup.c new file +5 -0

+		}
+		tst_brk(TBROK | TERRNO, "overlayfs mount failed");
+	}
+	return 0;
+}

Kind regards,
Petr

Quoted 10 lines

lib/tst_fs_setup.c line 37

Quoted 7 lines

lib/tst_fs_setup.c new file +7 -0

+	ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
+		    ",upperdir="OVL_UPPER",workdir="OVL_WORK);
+	if (ret < 0) {
+		if (errno == ENODEV) {
+			tst_res(TINFO,
+				"overlayfs is not configured in this kernel.");
+			return 1;

First I thought we'd implement it as a test flag (member of struct tst_test). When we have it as separate function I wonder whether we could TCONF on ENODEV instead of TINFO and return. Maybe there could be here for int strict parameter,

The return value is referenced in the testcase to determine whether to run tests in overlayfs. It's needed.

If this strict parameter is only for different wording on NODEV. Is it necessary ?

Hi Murphy,

Quoted 11 lines

Quoted 10 lines

lib/tst_fs_setup.c line 37

Quoted 7 lines

+ ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER

lib/tst_fs_setup.c new file +6 -0

+             ",upperdir="OVL_UPPER",workdir="OVL_WORK);
+ if (ret < 0) {
+         if (errno == ENODEV) {
+                 tst_res(TINFO,
+                         "overlayfs is not configured in this kernel.");
+                 return 1;

First I thought we'd implement it as a test flag (member of struct tst_test). When we have it as separate function I wonder whether we could TCONF on ENODEV instead of TINFO and return. Maybe there could be here for int strict parameter,

Quoted 5 lines

The return value is referenced in the testcase to determine whether to run tests in overlayfs. It's needed.

If this strict parameter is only for different wording on NODEV. Is it necessary ?

I'll recap my suggestions:
1) I like having macros to help reduce some parameters, this does not block functions being flexible (which requires parameters).
2) Having helper function create_overlay_dirs() used separately, than parameter in single function (Amir [1] suggestion makes sense).

Something like this, just a suggestion:

int create_overlay_dirs()

{
        SAFE_MKDIR(OVL_LOWER, 0755);
        ...
        return ret;
}

int mount_overlay(const char *file, const int lineno, int safe)

{
        ...
        if (create_overlay_dirs())
                tst_brk(TCONF, "...");

        ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
                    ",upperdir="OVL_UPPER",workdir="OVL_WORK);
        if (ret < 0) {
                if (errno == ENODEV) {
                        /*
                         * TODO: maybe safe is confusing as we use tst_brk(TBROK anyway),
                         * + sometimes tst_res(TCONF, ..) would be preferred over
                         * tst_brk(TCONF, ...)
                         */
                        if (safe)
                                tst_brk(TCONF,
                                        "overlayfs is not configured in this kernel.");
                        } else {
                                tst_res(TINFO,
                                        "overlayfs is not configured in this kernel.");
                                return 1;
                        }
                }
                tst_brk(TBROK | TERRNO, "overlayfs mount failed");
        }
}

#define SAFE_MOUNT_OVERLAY() \
        mount_overlay(__FILE__, __LINE__, 1);

#define TST_MOUNT_OVERLAY() \
        mount_overlay(__FILE__, __LINE__, 0);

Quoted 5 lines

#define SAFE_MOUNT_OVERLAY() \
        mount_overlay(__FILE__, __LINE__, 1);

#define TST_MOUNT_OVERLAY() \
        mount_overlay(__FILE__, __LINE__, 0);

I like this version of the helpers/macros.

I would change TST_MOUNT_OVERLAY to
(mount_overlay(__FILE__, __LINE__, 0) == 0)
so that it could be used like this:

ovl_mounted = TST_MOUNT_OVERLAY(...)

Uses of SAFE_MOUNT_OVERLAY() should not check return value could even place (void) in front of mount_overlay to enforce that.

Test that use SAFE_MOUNT_OVERLAY() should either have no variable ovl_mounted or set it after SAFE_MOUNT_OVERLAY() without checking return value.

Thanks,
Amir.

Hi Amir,

thanks for your suggestions, highly appreciated :).
...

Quoted 7 lines

Quoted 5 lines

#define SAFE_MOUNT_OVERLAY() \
        mount_overlay(__FILE__, __LINE__, 1);

#define TST_MOUNT_OVERLAY() \
        mount_overlay(__FILE__, __LINE__, 0);

Quoted 7 lines

I like this version of the helpers/macros.

I would change TST_MOUNT_OVERLAY to
(mount_overlay(__FILE__, __LINE__, 0) == 0)
so that it could be used like this:

ovl_mounted = TST_MOUNT_OVERLAY(...)

+1

Quoted 2 lines

Uses of SAFE_MOUNT_OVERLAY() should not check return value could even place (void) in front of mount_overlay to enforce that.

If we don't care, then it could be?

#define SAFE_MOUNT_OVERLAY() \
	(void) mount_overlay(__FILE__, __LINE__, 1);

I mean there is always mount_overlay() for special cases, macros should be here to make easier common usage.

Quoted 3 lines

Test that use SAFE_MOUNT_OVERLAY() should either have no variable ovl_mounted or set it after SAFE_MOUNT_OVERLAY() without checking return value.

+1

Quoted 2 lines

Thanks,
Amir.

Kind regards,
Petr

Hi Murphy, Amir, Cyril,

just a suggestion to apply diff below:

1) mount_overlay(): you don't actually use lineno and safe in error messages tst_fs_setup.c: In function ‘mount_overlay’:
tst_fs_setup.c:26:31: warning: unused parameter ‘file’ [-Wunused-parameter]
int mount_overlay(const char *file, const int lineno, int safe)

                   ~~~~~~~~~~~~^~~~

tst_fs_setup.c:26:47: warning: unused parameter ‘lineno’ [-Wunused-parameter]
int mount_overlay(const char *file, const int lineno, int safe)

2) mount_overlay(): return ret from mount (usually -1) instead of 1 (in case anybody is interested).

3) mount_overlay(): earlier return 0 after checking ENODEV saves us one shift right (but might look as error, as tst_res() is usually followed by return).

4) create_overlay_dirs(): checks for OVL_LOWER and thus can be called in mount_overlay() without any check. This saves us calling it before {SAFE,TST}_MOUNT_OVERLAY() in execveat03.c and readahead02.c

5) removed unused headers (<stdint.h>, <stdio.h>, <stdlib.h>, <sys/vfs.h>), is any of them needed and the need masked by it's include in tst_test.h?

5) other cleanup

TODO:
I'm still not sure about ovl_mounted. There is static int mntpoint_mounted in lib/tst_test.c, which does umount. tst_test->mntpoint, I guess we should use it. WDYT?

Quoted 6 lines

5) other cleanup

TODO:
I'm still not sure about ovl_mounted. There is static int mntpoint_mounted in lib/tst_test.c, which does umount. tst_test->mntpoint, I guess we should use it. WDYT?

It's not exactly the same as mntpoint_mounted.
In readahead02 ovl_mounted is used to decide whether to run test only on base fs or on base fs and also on overlayfs. Or maybe I did not understand what you mean.
For other tests ovl_moutned is only used for cleanup and could probably be replaced with mntpoint_mounted.

Thanks,
Amir.

Hi Murphy, Amir, Cyril,

just a suggestion to apply diff below:

1) mount_overlay(): you don't actually use lineno and safe in error messages tst_fs_setup.c: In function ‘mount_overlay’:
tst_fs_setup.c:26:31: warning: unused parameter ‘file’ [-Wunused-parameter]
int mount_overlay(const char *file, const int lineno, int safe)

                   ~~~~~~~~~~~~^~~~

tst_fs_setup.c:26:47: warning: unused parameter ‘lineno’ [-Wunused-parameter]
int mount_overlay(const char *file, const int lineno, int safe)

2) mount_overlay(): return ret from mount (usually -1) instead of 1 (in case anybody is interested).

3) mount_overlay(): earlier return 0 after checking ENODEV saves us one shift right (but might look as error, as tst_res() is usually followed by return).

4) create_overlay_dirs(): checks for OVL_LOWER and thus can be called in mount_overlay() without any check. This saves us calling it before {SAFE,TST}_MOUNT_OVERLAY() in execveat03.c and readahead02.c

5) removed unused headers (<stdint.h>, <stdio.h>, <stdlib.h>, <sys/vfs.h>), is any of them needed and the need masked by it's include in tst_test.h?

5) other cleanup

TODO:
I'm still not sure about ovl_mounted. There is static int mntpoint_mounted in lib/tst_test.c, which does umount. tst_test->mntpoint, I guess we should use it. WDYT?

Kind regards,
Petr
---
* diff to first commit:

tst_fs_setup.c +27 -27

index de09c7135..60dedc283 100644
@@ -1,46 +1,46 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * DESCRIPTION
- *	A place for setup filesystem helpers.
- */
 
-#include <stdint.h>
+#include <dirent.h>
 #include <errno.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/vfs.h>
 #include <sys/mount.h>
 
 #define TST_NO_DEFAULT_MAIN
 #include "tst_test.h"
 #include "tst_fs.h"
 
+#define TST_FS_SETUP_OVERLAYFS_MSG "overlayfs is not configured in this kernel"
+#define TST_FS_SETUP_OVERLAYFS_CONFIG "lowerdir="OVL_LOWER",upperdir="OVL_UPPER",workdir="OVL_WORK
+
 void create_overlay_dirs(void)
 {
-	SAFE_MKDIR(OVL_LOWER, 0755);
-	SAFE_MKDIR(OVL_UPPER, 0755);
-	SAFE_MKDIR(OVL_WORK, 0755);
-	SAFE_MKDIR(OVL_MNT, 0755);
+	DIR* dir = opendir(OVL_BASE_MNTPOINT);
+	if (!dir) {
+		SAFE_MKDIR(OVL_LOWER, 0755);
+		SAFE_MKDIR(OVL_UPPER, 0755);
+		SAFE_MKDIR(OVL_WORK, 0755);
+		SAFE_MKDIR(OVL_MNT, 0755);
+	}
 }
 
 int mount_overlay(const char *file, const int lineno, int safe)
 {
-	int ret = 0;
-	char *cfgmsg = "overlayfs is not configured in this kernel.";
-
-	ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
-		    ",upperdir="OVL_UPPER",workdir="OVL_WORK);
-	if (ret < 0) {
-		if (errno == ENODEV) {
-			if (safe) {
-				tst_brk(TCONF, cfgmsg);
-			} else {
-				tst_res(TINFO, cfgmsg);
-				return 1;
-			}
+	int ret;
+
+	create_overlay_dirs();
+
+	ret = mount("overlay", OVL_MNT, "overlay", 0, TST_FS_SETUP_OVERLAYFS_CONFIG);
+
+	if (!ret)
+		return 0;
+
+	if (errno == ENODEV) {
+		if (safe) {
+			tst_brk(TCONF, "%s:%d: " TST_FS_SETUP_OVERLAYFS_MSG, file, lineno);
 		} else {
-			tst_brk(TBROK | TERRNO, "overlayfs mount failed");
+			tst_res(TINFO, "%s:%d: " TST_FS_SETUP_OVERLAYFS_MSG, file, lineno);
 		}
+	} else {
+		tst_brk(TBROK | TERRNO, "overlayfs mount failed");
 	}
-	return 0;
+	return ret;
 }

* diff to second commit:

kernel/syscalls/execveat/execveat03.c +0 -2

index 446ff4f1d..eb088bc4c 100644
@@ -88,8 +88,6 @@ static void verify_execveat(void)
 static void setup(void)
 {
 	check_execveat();
-
-	create_overlay_dirs();
 	SAFE_MOUNT_OVERLAY();
 	ovl_mounted = 1;
 }

kernel/syscalls/inotify/inotify08.c +1 -1

index 929ed08f1..9433315e2 100644
@@ -165,7 +165,7 @@ static void setup(void)
 	if (fd_notify < 0) {
 		if (errno == ENOSYS) {
 			tst_brk(TCONF,
-				"inotify is not configured in this kernel.");
+				"inotify is not configured in this kernel");
 		} else {
 			tst_brk(TBROK | TERRNO,
 				"inotify_init () failed");

kernel/syscalls/readahead/readahead02.c +0 -1

index db95c2b01..f6e07173d 100644
@@ -388,7 +388,6 @@ static void setup(void)
 	setup_readahead_length();
 	tst_res(TINFO, "readahead length: %d", readahead_length);
 
-	create_overlay_dirs();
 	ovl_mounted = TST_MOUNT_OVERLAY();
 }

Quoted 4 lines

TODO:
I'm still not sure about ovl_mounted. There is static int mntpoint_mounted in lib/tst_test.c, which does umount. tst_test->mntpoint, I guess we should use it. WDYT?

mntpoint_mounted is tracking mount status of a separated mountpoint which is the base for creating overlay dirs and overlay mountpoint. This separated mountpoint is setup from scratch, grab dev, mfks etc. It's separated from runltp -d DIR. This is why this patch is needed.

Overlayfs is mounted on this separated mountpoint. Testcases need to umount overlayfs in cleanup if setup overlay successfully. That's why ovl_mounted is needed.

How about SAFE_UMOUNT_OVERLAY ignoring EINVAL ?

Thanks!
M

Hi Amir, Murphy,

Quoted 9 lines

Quoted 4 lines

TODO:
I'm still not sure about ovl_mounted. There is static int mntpoint_mounted in lib/tst_test.c, which does umount. tst_test->mntpoint, I guess we should use it. WDYT?

mntpoint_mounted is tracking mount status of a separated mountpoint which is the base for creating overlay dirs and overlay mountpoint. This separated mountpoint is setup from scratch, grab dev, mfks etc. It's separated from runltp -d DIR. This is why this patch is needed.

Quoted 5 lines

Overlayfs is mounted on this separated mountpoint. Testcases need to umount overlayfs in cleanup if setup overlay successfully. That's why ovl_mounted is needed.

How about SAFE_UMOUNT_OVERLAY ignoring EINVAL ?

I don't see much benefits, when we have SAFE_UMOUNT(). More useful looks to me for simple cases move ovl_mounted and SAFE_UMOUNT(OVL_MNT) to library (the only thing needed would be some flag for struct tst_test e.g. .mount_overlay = 1).

Quoted 3 lines

Thanks!
M

Kind regards,
Petr

Some tests are mounting overlayfs internally and run tests on it. This mount can fail if the filesystem we are running on does not support overlay mount upon it. For example, we are already running tests on overlayfs or NFS, or CIFS. Test will report broken and failure.

Fixing this by put overlayfs dirs in a separated mountpoint, like in readahead02 by Amir.

Suggested-by Petr Vorel <[email protected]>

Suggested-by Amir Goldstein <[email protected]>

Signed-off-by Murphy Zhou <[email protected]>

---
 .../kernel/syscalls/execveat/execveat03.c     | 31 ++--------------
 testcases/kernel/syscalls/inotify/inotify07.c | 33 ++++-------------
 testcases/kernel/syscalls/inotify/inotify08.c | 37 +++++--------------
 .../kernel/syscalls/readahead/readahead02.c   | 33 ++---------------
 4 files changed, 26 insertions(+), 108 deletions(-)

testcases/kernel/syscalls/execveat/execveat03.c +4 -27

index def33923b..7df1b0faa 100644
@@ -55,11 +55,10 @@
 #include "lapi/fcntl.h"
 #include "execveat.h"
 
-#define OVL_MNT "ovl"
 #define TEST_APP "execveat_child"
 #define TEST_FILE_PATH OVL_MNT"/"TEST_APP
 
-static int ovl_mounted;
+static const char mntpoint[] = OVL_BASE_MNTPOINT;
 
 static void do_child(void)
 {

@@ -86,31 +85,7 @@ static void verify_execveat(void)
 
 static void setup(void)
 {
-       int ret;
-
        check_execveat();
-
-       /* Setup an overlay mount with lower file */
-       SAFE_MKDIR("lower", 0755);
-       SAFE_MKDIR("upper", 0755);
-       SAFE_MKDIR("work", 0755);
-       SAFE_MKDIR(OVL_MNT, 0755);
-       ret = mount("overlay", OVL_MNT, "overlay", 0,
-                   "lowerdir=lower,upperdir=upper,workdir=work");
-       if (ret < 0) {
-               if (errno == ENODEV) {
-                       tst_brk(TCONF,
-                               "overlayfs is not configured in this kernel.");
-               }
-               tst_brk(TBROK | TERRNO, "overlayfs mount failed");
-       }
-       ovl_mounted = 1;
-}
-
-static void cleanup(void)
-{
-       if (ovl_mounted)
-               SAFE_UMOUNT(OVL_MNT);
 }
 
 static const char *const resource_files[] = {

@@ -121,10 +96,12 @@ static const char *const resource_files[] = {
 static struct tst_test test = {
        .needs_root = 1,
        .needs_tmpdir = 1,
+       .mount_device = 1,
+       .needs_overlay = 1,
+       .mntpoint = mntpoint,
        .forks_child = 1,
        .child_needs_reinit = 1,
        .setup = setup,
-       .cleanup = cleanup,
        .test_all = verify_execveat,
        .resource_files = resource_files,
 };

testcases/kernel/syscalls/inotify/inotify07.c +8 -25

index 96370b5cf..47817cd42 100644
@@ -73,13 +73,12 @@ struct event_t {
        unsigned int mask;
 };
 
-#define OVL_MNT "ovl"
 #define DIR_NAME "test_dir"
 #define DIR_PATH OVL_MNT"/"DIR_NAME
 #define FILE_NAME "test_file"
 #define FILE_PATH OVL_MNT"/"DIR_NAME"/"FILE_NAME
 
-static int ovl_mounted;
+static const char mntpoint[] = OVL_BASE_MNTPOINT;
 
 static struct event_t event_set[EVENT_MAX];
 

@@ -161,27 +160,12 @@ void verify_inotify(void)
 static void setup(void)
 {
        struct stat buf;
-       int ret;
 
        /* Setup an overlay mount with lower dir and file */
-       SAFE_MKDIR("lower", 0755);
-       SAFE_MKDIR("lower/"DIR_NAME, 0755);
-       SAFE_TOUCH("lower/"DIR_NAME"/"FILE_NAME, 0644, NULL);
-       SAFE_MKDIR("upper", 0755);
-       SAFE_MKDIR("work", 0755);
-       SAFE_MKDIR(OVL_MNT, 0755);
-       ret = mount("overlay", OVL_MNT, "overlay", 0,
-                   "lowerdir=lower,upperdir=upper,workdir=work");
-       if (ret < 0) {
-               if (errno == ENODEV) {
-                       tst_brk(TCONF,
-                               "overlayfs is not configured in this kernel.");
-               } else {
-                       tst_brk(TBROK | TERRNO,
-                               "overlayfs mount failed");
-               }
-       }
-       ovl_mounted = 1;
+       SAFE_UMOUNT(OVL_MNT);
+       SAFE_MKDIR(OVL_LOWER"/"DIR_NAME, 0755);
+       SAFE_TOUCH(OVL_LOWER"/"DIR_NAME"/"FILE_NAME, 0644, NULL);
+       SAFE_MOUNT_OVERLAY();
 
        fd_notify = myinotify_init1(O_NONBLOCK);
        if (fd_notify < 0) {

@@ -221,19 +205,18 @@ static void cleanup(void)
        if (reap_wd && myinotify_rm_watch(fd_notify, wd) < 0) {
                tst_res(TWARN,
                        "inotify_rm_watch (%d, %d) failed,", fd_notify, wd);
-
        }
 
        if (fd_notify > 0)
                SAFE_CLOSE(fd_notify);
-
-       if (ovl_mounted)
-               SAFE_UMOUNT(OVL_MNT);
 }
 
 static struct tst_test test = {
        .needs_root = 1,
        .needs_tmpdir = 1,
+       .mount_device = 1,
+       .needs_overlay = 1,
+       .mntpoint = mntpoint,
        .setup = setup,
        .cleanup = cleanup,
        .test_all = verify_inotify,

testcases/kernel/syscalls/inotify/inotify08.c +10 -27

index acdb95345..067c01dbb 100644
@@ -74,11 +74,10 @@ struct event_t {
        unsigned int mask;
 };
 
-#define OVL_MNT "ovl"
 #define FILE_NAME "test_file"
 #define FILE_PATH OVL_MNT"/"FILE_NAME
 
-static int ovl_mounted;
+static const char mntpoint[] = OVL_BASE_MNTPOINT;
 
 static struct event_t event_set[EVENT_MAX];
 

@@ -104,8 +103,8 @@ void verify_inotify(void)
        test_cnt++;
 
        /* Make sure events on upper/lower do not show in overlay watch */
-       SAFE_TOUCH("lower/"FILE_NAME, 0644, NULL);
-       SAFE_TOUCH("upper/"FILE_NAME, 0644, NULL);
+       SAFE_TOUCH(OVL_LOWER"/"FILE_NAME, 0644, NULL);
+       SAFE_TOUCH(OVL_UPPER"/"FILE_NAME, 0644, NULL);
 
        int len = read(fd_notify, event_buf, EVENT_BUF_LEN);
        if (len == -1 && errno != EAGAIN) {

@@ -154,32 +153,17 @@ void verify_inotify(void)
 static void setup(void)
 {
        struct stat buf;
-       int ret;
 
        /* Setup an overlay mount with lower file */
-       SAFE_MKDIR("lower", 0755);
-       SAFE_TOUCH("lower/"FILE_NAME, 0644, NULL);
-       SAFE_MKDIR("upper", 0755);
-       SAFE_MKDIR("work", 0755);
-       SAFE_MKDIR(OVL_MNT, 0755);
-       ret = mount("overlay", OVL_MNT, "overlay", 0,
-                   "lowerdir=lower,upperdir=upper,workdir=work");
-       if (ret < 0) {
-               if (errno == ENODEV) {
-                       tst_brk(TCONF,
-                               "overlayfs is not configured in this kernel.");
-               } else {
-                       tst_brk(TBROK | TERRNO,
-                               "overlayfs mount failed");
-               }
-       }
-       ovl_mounted = 1;
+       SAFE_UMOUNT(OVL_MNT);
+       SAFE_TOUCH(OVL_LOWER"/"FILE_NAME, 0644, NULL);
+       SAFE_MOUNT_OVERLAY();
 
        fd_notify = myinotify_init1(O_NONBLOCK);
        if (fd_notify < 0) {
                if (errno == ENOSYS) {
                        tst_brk(TCONF,
-                               "inotify is not configured in this kernel.");
+                               "inotify is not configured in this kernel");
                } else {
                        tst_brk(TBROK | TERRNO,
                                "inotify_init () failed");

@@ -217,19 +201,18 @@ static void cleanup(void)
        if (reap_wd && myinotify_rm_watch(fd_notify, wd) < 0) {
                tst_res(TWARN,
                        "inotify_rm_watch (%d, %d) failed,", fd_notify, wd);
-
        }
 
        if (fd_notify > 0)
                SAFE_CLOSE(fd_notify);
-
-       if (ovl_mounted)
-               SAFE_UMOUNT(OVL_MNT);
 }
 
 static struct tst_test test = {
        .needs_root = 1,
        .needs_tmpdir = 1,
+       .mount_device = 1,
+       .needs_overlay = 1,
+       .mntpoint = mntpoint,
        .setup = setup,
        .cleanup = cleanup,
        .test_all = verify_inotify,

testcases/kernel/syscalls/readahead/readahead02.c +4 -30

index 39ddbd583..f6e07173d 100644
@@ -44,16 +44,11 @@ static int pagesize;
 static unsigned long cached_max;
 static int ovl_mounted;
 
-#define MNTPOINT        "mntpoint"
-#define OVL_LOWER      MNTPOINT"/lower"
-#define OVL_UPPER      MNTPOINT"/upper"
-#define OVL_WORK       MNTPOINT"/work"
-#define OVL_MNT                MNTPOINT"/ovl"
 static int readahead_length  = 4096;
 static char sys_bdi_ra_path[PATH_MAX];
 static int orig_bdi_limit;
 
-static const char mntpoint[] = MNTPOINT;
+static const char mntpoint[] = OVL_BASE_MNTPOINT;
 
 static struct tst_option options[] = {
        {"s:", &opt_fsizestr, "-s    testfile size (default 64MB)"},

@@ -132,7 +127,8 @@ static void create_testfile(int use_overlay)
        char *tmp;
        size_t i;
 
-       sprintf(testfile, "%s/testfile", use_overlay ? OVL_MNT : MNTPOINT);
+       sprintf(testfile, "%s/testfile",
+               use_overlay ? OVL_MNT : OVL_BASE_MNTPOINT);
        tst_res(TINFO, "creating test file of size: %zu", testfile_size);
        tmp = SAFE_MALLOC(pagesize);
 

@@ -329,27 +325,6 @@ static void test_readahead(unsigned int n)
        }
 }
 
-static void setup_overlay(void)
-{
-       int ret;
-
-       /* Setup an overlay mount with lower dir and file */
-       SAFE_MKDIR(OVL_LOWER, 0755);
-       SAFE_MKDIR(OVL_UPPER, 0755);
-       SAFE_MKDIR(OVL_WORK, 0755);
-       SAFE_MKDIR(OVL_MNT, 0755);
-       ret = mount("overlay", OVL_MNT, "overlay", 0, "lowerdir="OVL_LOWER
-                   ",upperdir="OVL_UPPER",workdir="OVL_WORK);
-       if (ret < 0) {
-               if (errno == ENODEV) {
-                       tst_res(TINFO,
-                               "overlayfs is not configured in this kernel.");
-                       return;
-               }
-               tst_brk(TBROK | TERRNO, "overlayfs mount failed");
-       }
-       ovl_mounted = 1;
-}
 
 /*
  * We try raising bdi readahead limit as much as we can. We write

@@ -413,7 +388,7 @@ static void setup(void)
        setup_readahead_length();
        tst_res(TINFO, "readahead length: %d", readahead_length);
 
-       setup_overlay();
+       ovl_mounted = TST_MOUNT_OVERLAY();
 }
 
 static void cleanup(void)
--

2.21.0

Introduce tst_test->needs_overlay;
Define constraints of needed overlayfs dirs; create_overlay_dirs() to create lower/upper/work dirs; mount_overlay() to mount overlayfs;
SAFE_MOUNT_OVERLAY macro to mount overlayfs safely, tst_brk TCONF if mount fail with errno ENODEV;
TST_MOUNT_OVERLAY macro to mount overlayfs and return 0 if succeeds;

Suggested-by Petr Vorel <[email protected]>

Suggested-by Amir Goldstein <[email protected]>

Signed-off-by Murphy Zhou <[email protected]>

---

v5:
Introduce tst_test->needs_overlay to mount and umount overlay Several other fixes suggested by Petr
Update execveat03, inotify07/8 to use needs_overlay
v4:
Update ENODEV handle logic
Define TST_MOUNT_OVERLAY and SAFE_MOUNT_OVERLAY macros Change helper names
v3:
Split setup to 2 parts: creating files and mounting. Use macro SAFE_MOUNT_OVERLAYFS.
Handle ENODEV differently for 4 testcases we have modified.
v2:
define constraints in header file.
add a setup helper to create dirs and mount.

 include/safe_file_ops_fn.h  |  4 ++++
 include/tst_fs.h            |  6 +++++
 include/tst_safe_file_ops.h |  6 +++++
 include/tst_test.h          |  1 +
 lib/tst_fs_setup.c          | 48 +++++++++++++++++++++++++++++++++++++
 lib/tst_test.c              | 15 ++++++++++++
 6 files changed, 80 insertions(+)
 create mode 100644 lib/tst_fs_setup.c

include/safe_file_ops_fn.h +4 -0

index 35ec4fb1f..052fb1b9a 100644
@@ -76,4 +76,8 @@ void safe_touch(const char *file, const int lineno,
                const char *pathname,
                mode_t mode, const struct timespec times[2]);
 
+/* helper functions to setup overlayfs mountpoint */
+void create_overlay_dirs(void);
+int mount_overlay(const char *file, const int lineno, int skip);
+
 #endif /* SAFE_FILE_OPS_FN */

include/tst_fs.h +6 -0

index b2b19ada6..ebca065c6 100644
@@ -50,6 +50,12 @@ enum {
        TST_GB = 1073741824,
 };
 
+#define OVL_BASE_MNTPOINT        "mntpoint"
+#define OVL_LOWER      OVL_BASE_MNTPOINT"/lower"
+#define OVL_UPPER      OVL_BASE_MNTPOINT"/upper"
+#define OVL_WORK       OVL_BASE_MNTPOINT"/work"
+#define OVL_MNT                OVL_BASE_MNTPOINT"/ovl"
+
 /*
  * @path: path is the pathname of any file within the mounted file system
  * @mult: mult should be TST_KB, TST_MB or TST_GB

include/tst_safe_file_ops.h +6 -0

index 5c3fea4e2..b62a7447f 100644
@@ -59,4 +59,10 @@
        safe_touch(__FILE__, __LINE__, NULL, \
                        (pathname), (mode), (times))
 
+#define SAFE_MOUNT_OVERLAY() \
+       ((void) mount_overlay(__FILE__, __LINE__, 1))
+
+#define TST_MOUNT_OVERLAY() \
+       (mount_overlay(__FILE__, __LINE__, 0) == 0)
+
 #endif /* TST_SAFE_FILE_OPS */

include/tst_test.h +1 -0

index e4b935c45..f3b8901a2 100644
@@ -121,6 +121,7 @@ struct tst_test {
        int needs_root:1;
        int forks_child:1;
        int needs_device:1;
+       int needs_overlay:1;
        int needs_checkpoints:1;
        int format_device:1;
        int mount_device:1;

lib/tst_fs_setup.c new file +11 -0

new file mode 100644
index 000000000..e8ae929d7
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <dirent.h>
+#include <errno.h>
+#include <sys/mount.h>
+
+#define TST_NO_DEFAULT_MAIN
+#include "tst_test.h"
+#include "tst_fs.h"
+
+#define TST_FS_SETUP_OVERLAYFS_MSG "overlayfs is not configured in this kernel"

Quoted 9 lines · Murphy Zhou

Introduce tst_test->needs_overlay;
Define constraints of needed overlayfs dirs; create_overlay_dirs() to create lower/upper/work dirs; mount_overlay() to mount overlayfs;
SAFE_MOUNT_OVERLAY macro to mount overlayfs safely, tst_brk TCONF if mount fail with errno ENODEV;
TST_MOUNT_OVERLAY macro to mount overlayfs and return 0 if succeeds;

Quoted 4 lines

Suggested-by Petr Vorel <[email protected]>

Suggested-by Amir Goldstein <[email protected]>

Signed-off-by Murphy Zhou <[email protected]>

---

Very nice! just one minor comment, otherwise

Reviewed-by Amir Goldstein <[email protected]>

Quoted 102 lines

v5:
Introduce tst_test->needs_overlay to mount and umount overlay Several other fixes suggested by Petr
Update execveat03, inotify07/8 to use needs_overlay
v4:
Update ENODEV handle logic
Define TST_MOUNT_OVERLAY and SAFE_MOUNT_OVERLAY macros Change helper names
v3:
Split setup to 2 parts: creating files and mounting. Use macro SAFE_MOUNT_OVERLAYFS.
Handle ENODEV differently for 4 testcases we have modified.
v2:
define constraints in header file.
add a setup helper to create dirs and mount.

 include/safe_file_ops_fn.h  |  4 ++++
 include/tst_fs.h            |  6 +++++
 include/tst_safe_file_ops.h |  6 +++++
 include/tst_test.h          |  1 +
 lib/tst_fs_setup.c          | 48 +++++++++++++++++++++++++++++++++++++
 lib/tst_test.c              | 15 ++++++++++++
 6 files changed, 80 insertions(+)
 create mode 100644 lib/tst_fs_setup.c

include/safe_file_ops_fn.h +4 -0

index 35ec4fb1f..052fb1b9a 100644
@@ -76,4 +76,8 @@ void safe_touch(const char *file, const int lineno,
                const char *pathname,
                mode_t mode, const struct timespec times[2]);
 
+/* helper functions to setup overlayfs mountpoint */
+void create_overlay_dirs(void);
+int mount_overlay(const char *file, const int lineno, int skip);
+
 #endif /* SAFE_FILE_OPS_FN */

include/tst_fs.h +6 -0

index b2b19ada6..ebca065c6 100644
@@ -50,6 +50,12 @@ enum {
        TST_GB = 1073741824,
 };
 
+#define OVL_BASE_MNTPOINT        "mntpoint"
+#define OVL_LOWER      OVL_BASE_MNTPOINT"/lower"
+#define OVL_UPPER      OVL_BASE_MNTPOINT"/upper"
+#define OVL_WORK       OVL_BASE_MNTPOINT"/work"
+#define OVL_MNT                OVL_BASE_MNTPOINT"/ovl"
+
 /*
  * @path: path is the pathname of any file within the mounted file system
  * @mult: mult should be TST_KB, TST_MB or TST_GB

include/tst_safe_file_ops.h +6 -0

index 5c3fea4e2..b62a7447f 100644
@@ -59,4 +59,10 @@
        safe_touch(__FILE__, __LINE__, NULL, \
                        (pathname), (mode), (times))
 
+#define SAFE_MOUNT_OVERLAY() \
+       ((void) mount_overlay(__FILE__, __LINE__, 1))
+
+#define TST_MOUNT_OVERLAY() \
+       (mount_overlay(__FILE__, __LINE__, 0) == 0)
+
 #endif /* TST_SAFE_FILE_OPS */

include/tst_test.h +1 -0

index e4b935c45..f3b8901a2 100644
@@ -121,6 +121,7 @@ struct tst_test {
        int needs_root:1;
        int forks_child:1;
        int needs_device:1;
+       int needs_overlay:1;
        int needs_checkpoints:1;
        int format_device:1;
        int mount_device:1;

lib/tst_fs_setup.c new file +15 -0

new file mode 100644
index 000000000..e8ae929d7
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <dirent.h>
+#include <errno.h>
+#include <sys/mount.h>
+
+#define TST_NO_DEFAULT_MAIN
+#include "tst_test.h"
+#include "tst_fs.h"
+
+#define TST_FS_SETUP_OVERLAYFS_MSG "overlayfs is not configured in this kernel"
+#define TST_FS_SETUP_OVERLAYFS_CONFIG "lowerdir="OVL_LOWER",upperdir="OVL_UPPER",workdir="OVL_WORK
+
+void create_overlay_dirs(void)
+{