Generate random u64 max number correctly, and make it an obdclass
function lu_prandom_u64_max().
Fixes:
7a707d4828 (libcfs: replace cfs_rand() with prandom_u32_max())
Signed-off-by: Lai Siyao <lai.siyao@whamcloud.com>
Change-Id: I2b94a42b42539be319f358d7af2a82dc8b26117c
Reviewed-on: https://review.whamcloud.com/35394
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
int lqos_add_tgt(struct lu_qos *qos, struct lu_tgt_desc *ltd);
int lqos_del_tgt(struct lu_qos *qos, struct lu_tgt_desc *ltd);
+u64 lu_prandom_u64_max(u64 ep_ro);
/** @} lu */
#endif /* __LUSTRE_LU_OBJECT_H */
total_weight += tgt->ltd_qos.ltq_weight;
}
- if (total_weight) {
-#if BITS_PER_LONG == 32
- rand = prandom_u32_max((u32)total_weight);
- /*
- * If total_weight > 32-bit, first generate the high
- * 32 bits of the random number, then add in the low
- * 32 bits (truncated to the upper limit, if needed)
- */
- if (total_weight > 0xffffffffULL)
- rand = prandom_u32_max((u32)(total_weight >> 32)) << 32;
- else
- rand = 0;
-
- if (rand == (total_weight & 0xffffffff00000000ULL))
- rand |= prandom_u32_max((u32)total_weight);
- else
- rand |= prandom_u32();
-
-#else
- rand = prandom_u32() | prandom_u32_max((u32)total_weight);
-#endif
- } else {
- rand = 0;
- }
+ rand = lu_prandom_u64_max(total_weight);
for (i = 0; i < lmv->desc.ld_tgt_count; i++) {
tgt = lmv->tgts[i];
cur_weight = 0;
rc = -ENOSPC;
- if (total_weight) {
-#if BITS_PER_LONG == 32
- rand = prandom_u32_max((u32)total_weight);
- /* If total_weight > 32-bit, first generate the high
- * 32 bits of the random number, then add in the low
- * 32 bits (truncated to the upper limit, if needed)
- */
- if (total_weight > 0xffffffffULL)
- rand = prandom_u32_max((u32)(total_weight >> 32)) << 32;
- else
- rand = 0;
-
- if (rand == (total_weight & 0xffffffff00000000ULL))
- rand |= prandom_u32_max((u32)total_weight);
- else
- rand |= prandom_u32();
-
-#else
- rand = prandom_u32() | prandom_u32_max((u32)total_weight);
-#endif
- } else {
- rand = 0;
- }
+ rand = lu_prandom_u64_max(total_weight);
/* On average, this will hit larger-weighted OSTs more often.
* 0-weight OSTs will always get used last (only when rand=0) */
#include <linux/module.h>
#include <linux/list.h>
+#include <linux/random.h>
#include <libcfs/libcfs.h>
#include <libcfs/libcfs_hash.h> /* hash_long() */
#include <libcfs/linux/linux-mem.h>
RETURN(rc);
}
EXPORT_SYMBOL(lqos_del_tgt);
+
+/**
+ * lu_prandom_u64_max - returns a pseudo-random u64 number in interval
+ * [0, ep_ro)
+ *
+ * \param[in] ep_ro right open interval endpoint
+ *
+ * \retval a pseudo-random 64-bit number that is in interval [0, ep_ro).
+ */
+u64 lu_prandom_u64_max(u64 ep_ro)
+{
+ u64 rand = 0;
+
+ if (ep_ro) {
+#if BITS_PER_LONG == 32
+ /*
+ * If ep_ro > 32-bit, first generate the high
+ * 32 bits of the random number, then add in the low
+ * 32 bits (truncated to the upper limit, if needed)
+ */
+ if (ep_ro > 0xffffffffULL)
+ rand = prandom_u32_max((u32)(ep_ro >> 32)) << 32;
+
+ if (rand == (ep_ro & 0xffffffff00000000ULL))
+ rand |= prandom_u32_max((u32)ep_ro);
+ else
+ rand |= prandom_u32();
+#else
+ rand = ((u64)prandom_u32() << 32 | prandom_u32()) % ep_ro;
+#endif
+ }
+
+ return rand;
+}
+EXPORT_SYMBOL(lu_prandom_u64_max);