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

Yang Xu
2019-07-17T09:44:34Z

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)
{
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