[LTP] [PATCH v5 1/3] lib: alter find_free_loopdev()

Amir Goldstein
2019-07-17T10:14:21Z

On Wed, Jul 17, 2019 at 12:45 PM Yang Xu <xuyang2018.jy@cn.fujitsu.com> wrote:
>
> Alter find_free_loopdev() to tst_find_free_loopdev(path, path_len),
> it passes the dev_path inside of the tst_device.c and NULL from other
> tests. It returns the free loopdev minor (and -1 for no free loopdev).
> We can call tst_find_free_loopdev(NULL, 0) to get a free minor number
> without changing lib internal state.
>
> Signed-off-by: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> ---
> doc/test-writing-guidelines.txt | 12 ++++++++++++
> include/tst_device.h | 5 +++++
> lib/tst_device.c | 34 +++++++++++++++++----------------
> 3 files changed, 35 insertions(+), 16 deletions(-)
>
> diff --git a/doc/test-writing-guidelines.txt b/doc/test-writing-guidelines.txt
> index 4b1e7d25b..c65c707e6 100644
> --- a/doc/test-writing-guidelines.txt
> +++ b/doc/test-writing-guidelines.txt
> @@ -1045,6 +1045,18 @@ IMPORTANT: All testcases should use 'tst_umount()' instead of 'umount(2)' to
> -------------------------------------------------------------------------------
> #include "tst_test.h"
>
> +int tst_find_free_loopdev(const char *path, size_t path_len);
> +-------------------------------------------------------------------------------
> +
> +This function finds a free loopdev and returns the free loopdev minor (-1 for no
> +free loopdev). If path is non-NULL, it will be filled with free loopdev path.
> +We can call tst_find_free_loopdev(NULL, 0) in tests to get a free minor number
> +without changing lib internal state.
> +
> +[source,c]
> +-------------------------------------------------------------------------------
> +#include "tst_test.h"
> +
> unsigned long tst_dev_bytes_written(const char *dev);
> -------------------------------------------------------------------------------
>
> diff --git a/include/tst_device.h b/include/tst_device.h
> index 61902b7e0..42b9fa95b 100644
> --- a/include/tst_device.h
> +++ b/include/tst_device.h
> @@ -44,6 +44,11 @@ int tst_umount(const char *path);
> */
> int tst_clear_device(const char *dev);
>
> +/*
> + * Finds a free loop device for use and returns the free loopdev minor(-1 for no
> + * free loopdev). If path is non-NULL, it will be filled with free loopdev path.
> + */
> +int tst_find_free_loopdev(const char *path, size_t path_len);
> /*
> * Reads test block device stat file and returns the bytes written since the
> * last call of this function.
> diff --git a/lib/tst_device.c b/lib/tst_device.c
> index 65fcc1337..f2516fb08 100644
> --- a/lib/tst_device.c
> +++ b/lib/tst_device.c
> @@ -53,22 +53,22 @@ static const char *dev_variants[] = {
> "/dev/block/loop%i"
> };
>
> -static int set_dev_path(int dev)
> +static int set_dev_path(int dev, char *path, size_t path_len)
> {
> unsigned int i;
> struct stat st;
>
> for (i = 0; i < ARRAY_SIZE(dev_variants); i++) {
> - snprintf(dev_path, sizeof(dev_path), dev_variants[i], dev);
> + snprintf(path, path_len, dev_variants[i], dev);
>
> - if (stat(dev_path, &st) == 0 && S_ISBLK(st.st_mode))
> + if (stat(path, &st) == 0 && S_ISBLK(st.st_mode))
> return 1;
> }
>
> return 0;
> }
>
> -static int find_free_loopdev(void)
> +int tst_find_free_loopdev(char *path, size_t path_len)

Another option is to leave this function internal and export a wrapper
for the exact needed functionality:

/* Just find a free minor number */
int tst_find_free_loopdev(void)
{
return find_free_loopdev(NULL, 0);
}

I don't mind wither way.

> {
> int ctl_fd, dev_fd, rc, i;
> struct loop_info loopinfo;
> @@ -80,12 +80,14 @@ static int find_free_loopdev(void)
> rc = ioctl(ctl_fd, LOOP_CTL_GET_FREE);
> close(ctl_fd);
> if (rc >= 0) {
> - set_dev_path(rc);
> - tst_resm(TINFO, "Found free device '%s'", dev_path);
> - return 0;
> + if (path)
> + set_dev_path(rc, path, path_len);
> + tst_resm(TINFO, "Found free device %d '%s'",
> + rc, path ?: "");
> + return rc;
> }
> tst_resm(TINFO, "Couldn't find free loop device");
> - return 1;
> + return -1;
> }
>
> switch (errno) {
> @@ -104,24 +106,24 @@ static int find_free_loopdev(void)
> * Older way is to iterate over /dev/loop%i and /dev/loop/%i and try
> * LOOP_GET_STATUS ioctl() which fails for free loop devices.
> */
> - for (i = 0; i < 256; i++) {
> + for (i = 0; path && i < 256; i++) {
>
> - if (!set_dev_path(i))
> + if (!set_dev_path(i, path, path_len))
> continue;
>
> - dev_fd = open(dev_path, O_RDONLY);
> + dev_fd = open(path, O_RDONLY);
>
> if (dev_fd < 0)
> continue;
>
> if (ioctl(dev_fd, LOOP_GET_STATUS, &loopinfo) == 0) {
> - tst_resm(TINFO, "Device '%s' in use", dev_path);
> + tst_resm(TINFO, "Device '%s' in use", path);
> } else {
> if (errno != ENXIO)
> continue;
> - tst_resm(TINFO, "Found free device '%s'", dev_path);
> + tst_resm(TINFO, "Found free device '%s'", path);
> close(dev_fd);
> - return 0;
> + return i;
> }
>
> close(dev_fd);
> @@ -129,7 +131,7 @@ static int find_free_loopdev(void)
>
> tst_resm(TINFO, "No free devices found");
>
> - return 1;
> + return -1;
> }
>
> static int attach_device(const char *dev, const char *file)
> @@ -274,7 +276,7 @@ const char *tst_acquire_device__(unsigned int size)
> return NULL;
> }
>
> - if (find_free_loopdev())
> + if (tst_find_free_loopdev(dev_path, sizeof(dev_path)) == -1)
> return NULL;
>
> if (attach_device(dev_path, DEV_FILE))
> --
> 2.18.1
>
>
>