lib: make tst_detach_device_by_fd() also close dev_fd

Since commit 18048c1af783 ("loop: Fix a race between loop detach and loop open")
detach operation is deferred to the last close of the device.

Make tst_detach_device_by_fd() also close dev_fd, and leave it up to
caller to re-open it for further use.

Closes: #1175

Reported-by: Gulam Mohamed <[email protected]>
Signed-off-by: Jan Stancek <[email protected]>
Reviewed-by: Petr Vorel <[email protected]>
Tested-by: Petr Vorel <[email protected]>
Reviewed-by: Li Wang <[email protected]>

include/tst_device.h

@@ -67,7 +67,9 @@ int tst_attach_device(const char *dev_path, const char *file_path);
 uint64_t tst_get_device_size(const char *dev_path);
 
 /*
- * Detaches a file from a loop device fd.
+ * Detaches a file from a loop device fd. @dev_fd needs to be the
+ * last descriptor opened. Call to this function will close it,
+ * it is up to caller to open it again for further usage.
  *
  * @dev_path Path to the loop device e.g. /dev/loop0
  * @dev_fd a open fd for the loop device

lib/tst_device.c

@@ -243,17 +243,23 @@ int tst_detach_device_by_fd(const char *dev, int dev_fd)
 
 	/* keep trying to clear LOOPDEV until we get ENXIO, a quick succession
 	 * of attach/detach might not give udev enough time to complete
+	 *
+	 * Since 18048c1af783 ("loop: Fix a race between loop detach and loop open")
+	 * device is detached only after last close.
 	 */
 	for (i = 0; i < 40; i++) {
 		ret = ioctl(dev_fd, LOOP_CLR_FD, 0);
 
-		if (ret && (errno == ENXIO))
+		if (ret && (errno == ENXIO)) {
+			SAFE_CLOSE(NULL, dev_fd);
 			return 0;
+		}
 
 		if (ret && (errno != EBUSY)) {
 			tst_resm(TWARN,
 				 "ioctl(%s, LOOP_CLR_FD, 0) unexpectedly failed with: %s",
 				 dev, tst_strerrno(errno));
+			SAFE_CLOSE(NULL, dev_fd);
 			return 1;
 		}
 
@@ -262,6 +268,7 @@ int tst_detach_device_by_fd(const char *dev, int dev_fd)
 
 	tst_resm(TWARN,
 		"ioctl(%s, LOOP_CLR_FD, 0) no ENXIO for too long", dev);
+	SAFE_CLOSE(NULL, dev_fd);
 	return 1;
 }
 
@@ -276,7 +283,6 @@ int tst_detach_device(const char *dev)
 	}
 
 	ret = tst_detach_device_by_fd(dev, dev_fd);
-	close(dev_fd);
 	return ret;
 }
 

testcases/kernel/syscalls/ioctl/ioctl09.c

@@ -88,6 +88,7 @@ static void verify_ioctl(void)
 	check_partition(2, true);
 
 	tst_detach_device_by_fd(dev_path, dev_fd);
+	dev_fd = SAFE_OPEN(dev_path, O_RDWR);
 	attach_flag = 0;
 }
 

testcases/kernel/syscalls/ioctl/ioctl_loop01.c

@@ -93,6 +93,7 @@ static void verify_ioctl_loop(void)
 	check_loop_value(0, LO_FLAGS_PARTSCAN, 0);
 
 	tst_detach_device_by_fd(dev_path, dev_fd);
+	dev_fd = SAFE_OPEN(dev_path, O_RDWR);
 	attach_flag = 0;
 }
 

testcases/kernel/syscalls/ioctl/ioctl_loop02.c

@@ -103,6 +103,7 @@ static void verify_ioctl_loop(unsigned int n)
 
 	SAFE_CLOSE(file_fd);
 	tst_detach_device_by_fd(dev_path, dev_fd);
+	dev_fd = SAFE_OPEN(dev_path, O_RDWR);
 	attach_flag = 0;
 }
 

testcases/kernel/syscalls/ioctl/ioctl_loop04.c

@@ -63,6 +63,7 @@ static void verify_ioctl_loop(void)
 
 	SAFE_CLOSE(file_fd);
 	tst_detach_device_by_fd(dev_path, dev_fd);
+	dev_fd = SAFE_OPEN(dev_path, O_RDWR);
 	unlink("test.img");
 	attach_flag = 0;
 }

testcases/kernel/syscalls/ioctl/ioctl_loop06.c

@@ -57,8 +57,10 @@ static void verify_ioctl_loop(unsigned int n)
 
 	if (TST_RET == 0) {
 		tst_res(TFAIL, "Set block size succeed unexpectedly");
-		if (tcases[n].ioctl_flag == LOOP_CONFIGURE)
+		if (tcases[n].ioctl_flag == LOOP_CONFIGURE) {
 			tst_detach_device_by_fd(dev_path, dev_fd);
+			dev_fd = SAFE_OPEN(dev_path, O_RDWR);
+		}
 		return;
 	}
 	if (TST_ERR == EINVAL)
@@ -87,6 +89,7 @@ static void run(unsigned int n)
 	}
 	if (attach_flag) {
 		tst_detach_device_by_fd(dev_path, dev_fd);
+		dev_fd = SAFE_OPEN(dev_path, O_RDWR);
 		attach_flag = 0;
 	}
 	loopconfig.block_size = *(tc->setvalue);

testcases/kernel/syscalls/ioctl/ioctl_loop07.c

@@ -73,6 +73,7 @@ static void verify_ioctl_loop(unsigned int n)
 	/*Reset*/
 	if (tc->ioctl_flag == LOOP_CONFIGURE) {
 		tst_detach_device_by_fd(dev_path, dev_fd);
+		dev_fd = SAFE_OPEN(dev_path, O_RDWR);
 	} else {
 		loopinfo.lo_sizelimit = 0;
 		TST_RETRY_FUNC(ioctl(dev_fd, LOOP_SET_STATUS, &loopinfo), TST_RETVAL_EQ0);
@@ -101,6 +102,7 @@ static void run(unsigned int n)
 	}
 	if (attach_flag) {
 		tst_detach_device_by_fd(dev_path, dev_fd);
+		dev_fd = SAFE_OPEN(dev_path, O_RDWR);
 		attach_flag = 0;
 	}
 	loopconfig.info.lo_sizelimit = tc->set_sizelimit;