[v1] Add tst_dev_block_size utility

Added tst_dev_block_size function in tst_device.c and updated
c-test-api.txt documentation.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.de>
---
 doc/c-test-api.txt            | 11 ++++
 include/tst_device.h          |  7 +++
 lib/newlib_tests/tst_device.c | 95 +++++++++++++++++++++++++++--------
 lib/tst_device.c              | 15 ++++++
 4 files changed, 108 insertions(+), 20 deletions(-)

Hi! Please ignore this implementation, since it's not using fallback 
lapi/loop.h and it causes build issues with kernel < 4.13

On 1/14/22 15:25, Andrea Cervesato wrote:
> Added tst_dev_block_size function in tst_device.c and updated
> c-test-api.txt documentation.
>
> Signed-off-by: Andrea Cervesato<andrea.cervesato@suse.de>
> ---
>   doc/c-test-api.txt            | 11 ++++
>   include/tst_device.h          |  7 +++
>   lib/newlib_tests/tst_device.c | 95 +++++++++++++++++++++++++++--------
>   lib/tst_device.c              | 15 ++++++
>   4 files changed, 108 insertions(+), 20 deletions(-)
>
> diff --git a/doc/c-test-api.txt b/doc/c-test-api.txt
> index 123d3f1fc..0cb391a0a 100644
> --- a/doc/c-test-api.txt
> +++ b/doc/c-test-api.txt
> @@ -1034,6 +1034,17 @@ uint64_t tst_get_device_size(const char *dev_path);
>   This function gets size of the given block device, it checks the 'dev_path' is
>   valid first, if yes, return the size in MB, otherwise return -1.
>   
> +[source,c]
> +-------------------------------------------------------------------------------
> +#include "tst_test.h"
> +
> +int tst_dev_block_size(const char *path);
> +-------------------------------------------------------------------------------
> +
> +This function returns the size of a single IO block for the specific `path`.
> +It finds the device where `path` is located and then uses `ioctl` to get a
> +single device block size.
> +
>   1.16 Formatting a device with a filesystem
>   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   
> diff --git a/include/tst_device.h b/include/tst_device.h
> index 72c560c02..bf0fb5320 100644
> --- a/include/tst_device.h
> +++ b/include/tst_device.h
> @@ -112,4 +112,11 @@ void tst_purge_dir(const char *path);
>    */
>   void tst_find_backing_dev(const char *path, char *dev);
>   
> +/*
> + * Returns the size of a single IO block for the specific path
> + * @path   Path to find the block size
> + * @return Size of the block size
> + */
> +int tst_dev_block_size(const char *path);
> +
>   #endif	/* TST_DEVICE_H__ */
> diff --git a/lib/newlib_tests/tst_device.c b/lib/newlib_tests/tst_device.c
> index 0bee0a939..1f754e63d 100644
> --- a/lib/newlib_tests/tst_device.c
> +++ b/lib/newlib_tests/tst_device.c
> @@ -1,47 +1,102 @@
>   // SPDX-License-Identifier: GPL-2.0-or-later
>   /*
>    * Copyright (c) 2016 Linux Test Project
> + * Copyright (C) 2021 SUSE LLC Andrea Cervesato<andrea.cervesato@suse.com>
>    */
> +#define _GNU_SOURCE
>   
>   #include <stdlib.h>
>   #include <sys/mount.h>
>   #include <stdint.h>
> +#include <stdio.h>
> +#include <linux/loop.h>
> +#include <time.h>
>   
>   #include "tst_test.h"
>   
> -static void do_test(void)
> +#define PAGESIZE 2048
> +#define DEV_MIN_SIZE 300
> +
> +static char *mntpoint;
> +static uint64_t ltp_dev_size;
> +
> +static void setup(void)
>   {
>   	int fd;
> -	const char *dev;
> -	char block_dev[100];
> -	uint64_t ltp_dev_size;
> +	int ret;
>   
> -	dev = tst_device->dev;
> -	if (!dev)
> -		tst_brk(TCONF, "Failed to acquire test device");
> +	ret = asprintf(&mntpoint, "%s/mnt", tst_get_tmpdir());
> +	if (ret < 0)
> +		tst_brk(TBROK, "asprintf failure");
>   
> -	SAFE_MKFS(dev, "ext2", NULL, NULL);
> +	while ((fd = SAFE_OPEN(tst_device->dev, O_RDONLY, 0666)) < 0)
> +		usleep(100);
>   
> -	fd = SAFE_OPEN(dev, O_RDONLY);
>   	SAFE_IOCTL(fd, BLKGETSIZE64, &ltp_dev_size);
> +	SAFE_IOCTL(fd, LOOP_SET_BLOCK_SIZE, PAGESIZE);
>   	SAFE_CLOSE(fd);
>   
> -	if (ltp_dev_size/1024/1024 == 300)
> -		tst_res(TPASS, "Got expected device size");
> +	SAFE_MKFS(tst_device->dev, tst_device->fs_type, NULL, NULL);
> +
> +	SAFE_MKDIR(mntpoint, 0777);
> +	SAFE_MOUNT(tst_device->dev, mntpoint, tst_device->fs_type, 0, 0);
> +}
> +
> +static void cleanup(void)
> +{
> +	if (tst_is_mounted(mntpoint))
> +		SAFE_UMOUNT(mntpoint);
> +}
> +
> +static void test_dev_min_size(void)
> +{
> +	uint64_t size;
> +
> +	size = ltp_dev_size / 1024 / 1024;
> +
> +	if (size == DEV_MIN_SIZE)
> +		tst_res(TPASS, "Got expected device size %lu", size);
> +	else
> +		tst_res(TFAIL, "Expected device size is %d but got %lu", DEV_MIN_SIZE, size);
> +}
> +
> +static void test_tst_find_backing_dev(void)
> +{
> +	char block_dev[100];
> +
> +	tst_find_backing_dev(mntpoint, block_dev);
> +
> +	if (!strcmp(tst_device->dev, block_dev))
> +		tst_res(TPASS, "%s belongs to %s block dev", mntpoint, block_dev);
>   	else
> -		tst_res(TFAIL, "Got unexpected device size");
> -
> -	tst_find_backing_dev("/boot", block_dev);
> -	tst_res(TPASS, "/boot belongs to %s block dev", block_dev);
> -	tst_find_backing_dev("/", block_dev);
> -	tst_res(TPASS, "/ belongs to %s block dev", block_dev);
> -	tst_find_backing_dev("/tmp", block_dev);
> -	tst_find_backing_dev("/boot/xuyang", block_dev);
> +		tst_res(TFAIL, "%s should belong to %s, but %s is returned", mntpoint, tst_device->dev, block_dev);
> +}
> +
> +static void test_tst_dev_block_size(void)
> +{
> +	int block_size;
> +
> +	block_size = tst_dev_block_size(mntpoint);
> +
> +	if (block_size == PAGESIZE)
> +		tst_res(TPASS, "%s has %d block size", mntpoint, block_size);
> +	else
> +		tst_res(TFAIL, "%s has %d block size, but expected is %i", mntpoint, block_size, PAGESIZE);
> +}
> +
> +static void do_test(void)
> +{
> +	test_dev_min_size();
> +	test_tst_find_backing_dev();
> +	test_tst_dev_block_size();
>   }
>   
>   static struct tst_test test = {
>   	.needs_root = 1,
>   	.needs_device = 1,
> -	.dev_min_size = 300,
> +	.needs_tmpdir = 1,
> +	.dev_min_size = DEV_MIN_SIZE,
>   	.test_all = do_test,
> +	.setup = setup,
> +	.cleanup = cleanup,
>   };
> diff --git a/lib/tst_device.c b/lib/tst_device.c
> index 73e70d26e..1ef667fa0 100644
> --- a/lib/tst_device.c
> +++ b/lib/tst_device.c
> @@ -547,3 +547,18 @@ void tst_find_backing_dev(const char *path, char *dev)
>   	if (S_ISBLK(buf.st_mode) != 1)
>   		tst_brkm(TCONF, NULL, "dev(%s) isn't a block dev", dev);
>   }
> +
> +int tst_dev_block_size(const char *path)
> +{
> +	int fd;
> +	int size;
> +	char dev_name[1024];
> +
> +	tst_find_backing_dev(path, dev_name);
> +
> +	fd = SAFE_OPEN(NULL, dev_name, O_RDONLY);
> +	SAFE_IOCTL(NULL, fd, BLKSSZGET, &size);
> +	SAFE_CLOSE(NULL, fd);
> +
> +	return size;
> +}