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md: factor out parsing of fixed-point numbers

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safe_delay_store can parse fixed point numbers (for fractions
of a second).  We will want to do that for another sysfs
file soon, so factor out the code.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2009-12-14 12:49:55 +11:00
parent f6af949c56
commit 72e02075a3
2 changed files with 44 additions and 23 deletions
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64
drivers/md/md.c
View file

@ -2763,6 +2763,47 @@ static void analyze_sbs(mddev_t * mddev)
}
}
/* Read a fixed-point number.
* Numbers in sysfs attributes should be in "standard" units where
* possible, so time should be in seconds.
* However we internally use a a much smaller unit such as
* milliseconds or jiffies.
* This function takes a decimal number with a possible fractional
* component, and produces an integer which is the result of
* multiplying that number by 10^'scale'.
* all without any floating-point arithmetic.
*/
int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale)
{
unsigned long result = 0;
long decimals = -1;
while (isdigit(*cp) || (*cp == '.' && decimals < 0)) {
if (*cp == '.')
decimals = 0;
else if (decimals < scale) {
unsigned int value;
value = *cp - '0';
result = result * 10 + value;
if (decimals >= 0)
decimals++;
}
cp++;
}
if (*cp == '\n')
cp++;
if (*cp)
return -EINVAL;
if (decimals < 0)
decimals = 0;
while (decimals < scale) {
result *= 10;
decimals ++;
}
*res = result;
return 0;
}
static void md_safemode_timeout(unsigned long data);
static ssize_t
@ -2774,31 +2815,10 @@ safe_delay_show(mddev_t *mddev, char *page)
static ssize_t
safe_delay_store(mddev_t *mddev, const char *cbuf, size_t len)
{
int scale=1;
int dot=0;
int i;
unsigned long msec;
char buf[30];
/* remove a period, and count digits after it */
if (len >= sizeof(buf))
if (strict_strtoul_scaled(cbuf, &msec, 3) < 0)
return -EINVAL;
strlcpy(buf, cbuf, sizeof(buf));
for (i=0; i<len; i++) {
if (dot) {
if (isdigit(buf[i])) {
buf[i-1] = buf[i];
scale *= 10;
}
buf[i] = 0;
} else if (buf[i] == '.') {
dot=1;
buf[i] = 0;
}
}
if (strict_strtoul(buf, 10, &msec) < 0)
return -EINVAL;
msec = (msec * 1000) / scale;
if (msec == 0)
mddev->safemode_delay = 0;
else {

3
drivers/md/md.h
View file

@ -463,6 +463,7 @@ extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
extern void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors);
extern int md_check_no_bitmap(mddev_t *mddev);
extern int md_integrity_register(mddev_t *mddev);
void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
extern void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
#endif /* _MD_MD_H */