md: factor out parsing of fixed-point numbers

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>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index c56c64d..93287f8 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -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))
-               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)
+       if (strict_strtoul_scaled(cbuf, &msec, 3) < 0)
                return -EINVAL;
-       msec = (msec * 1000) / scale;
        if (msec == 0)
                mddev->safemode_delay = 0;
        else {

diff --git a/drivers/md/md.h b/drivers/md/md.h
index df69295..b5c3069 100644 (file)
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -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 */