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authorLinus Torvalds <torvalds@linux-foundation.org>2013-09-10 13:06:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-10 13:06:15 -0700
commit7426d62871dafbeeed087d609c6469a515c88389 (patch)
tree7d935f360eeb5e78ba633238a29e9213c291aad7 /lib
parent4d7696f1b05f4aeb586c74868fe3da2731daca4b (diff)
parent7fff5e8f727285cf54e6aba10f31b196f207b98a (diff)
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Merge tag 'dm-3.12-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device-mapper updates from Mike Snitzer: "Add the ability to collect I/O statistics on user-defined regions of a device-mapper device. This dm-stats code required the reintroduction of a div64_u64_rem() helper, but as a separate method that doesn't slow down div64_u64() -- especially on 32-bit systems. Allow the error target to replace request-based DM devices (e.g. multipath) in addition to bio-based DM devices. Various other small code fixes and improvements to thin-provisioning, DM cache and the DM ioctl interface" * tag 'dm-3.12-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm stripe: silence a couple sparse warnings dm: add statistics support dm thin: always return -ENOSPC if no_free_space is set dm ioctl: cleanup error handling in table_load dm ioctl: increase granularity of type_lock when loading table dm ioctl: prevent rename to empty name or uuid dm thin: set pool read-only if breaking_sharing fails block allocation dm thin: prefix pool error messages with pool device name dm: allow error target to replace bio-based and request-based targets math64: New separate div64_u64_rem helper dm space map: optimise sm_ll_dec and sm_ll_inc dm btree: prefetch child nodes when walking tree for a dm_btree_del dm btree: use pop_frame in dm_btree_del to cleanup code dm cache: eliminate holes in cache structure dm cache: fix stacking of geometry limits dm thin: fix stacking of geometry limits dm thin: add data block size limits to Documentation dm cache: add data block size limits to code and Documentation dm cache: document metadata device is exclussive to a cache dm: stop using WQ_NON_REENTRANT
Diffstat (limited to 'lib')
-rw-r--r--lib/div64.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/lib/div64.c b/lib/div64.c
index a163b6caef73..4382ad77777e 100644
--- a/lib/div64.c
+++ b/lib/div64.c
@@ -79,6 +79,46 @@ EXPORT_SYMBOL(div_s64_rem);
#endif
/**
+ * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
+ * @dividend: 64bit dividend
+ * @divisor: 64bit divisor
+ * @remainder: 64bit remainder
+ *
+ * This implementation is a comparable to algorithm used by div64_u64.
+ * But this operation, which includes math for calculating the remainder,
+ * is kept distinct to avoid slowing down the div64_u64 operation on 32bit
+ * systems.
+ */
+#ifndef div64_u64_rem
+u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
+{
+ u32 high = divisor >> 32;
+ u64 quot;
+
+ if (high == 0) {
+ u32 rem32;
+ quot = div_u64_rem(dividend, divisor, &rem32);
+ *remainder = rem32;
+ } else {
+ int n = 1 + fls(high);
+ quot = div_u64(dividend >> n, divisor >> n);
+
+ if (quot != 0)
+ quot--;
+
+ *remainder = dividend - quot * divisor;
+ if (*remainder >= divisor) {
+ quot++;
+ *remainder -= divisor;
+ }
+ }
+
+ return quot;
+}
+EXPORT_SYMBOL(div64_u64_rem);
+#endif
+
+/**
* div64_u64 - unsigned 64bit divide with 64bit divisor
* @dividend: 64bit dividend
* @divisor: 64bit divisor