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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/module.h>#include <linux/gfp.h>#include <linux/raid/pq.h>#include <linux/slab.h>#include <linux/static_call.h>#include <kunit/visibility.h>#include "algos.h"
#define RAID6_MAX_ALGOS 16static const struct raid6_calls *raid6_algos[RAID6_MAX_ALGOS];static unsigned int raid6_nr_algos;static const struct raid6_recov_calls *raid6_recov_algo;
/* Selected algorithm */DEFINE_STATIC_CALL_NULL(raid6_gen_syndrome_impl, *raid6_intx1.gen_syndrome);DEFINE_STATIC_CALL_NULL(raid6_xor_syndrome_impl, *raid6_intx1.xor_syndrome);DEFINE_STATIC_CALL_NULL(raid6_recov_2data_impl, *raid6_recov_intx1.data2);DEFINE_STATIC_CALL_NULL(raid6_recov_datap_impl, *raid6_recov_intx1.datap);
/** * raid6_gen_syndrome - generate RAID6 P/Q parity * @disks: number of "disks" to operate on including parity * @bytes: length in bytes of each vector * @ptrs: @disks size array of memory pointers * * Generate @bytes worth of RAID6 P and Q parity in @ptrs[@disks - 2] and * @ptrs[@disks - 1] respectively from the memory pointed to by @ptrs[0] to * @ptrs[@disks - 3]. * * @disks must be at least 4, and the memory pointed to by each member of @ptrs * must be at least 64-byte aligned. @bytes must be non-zero and a multiple of * 512. * * See https://kernel.org/pub/linux/kernel/people/hpa/raid6.pdf for underlying * algorithm. */void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs){ WARN_ON_ONCE(!in_task() || irqs_disabled() || softirq_count()); WARN_ON_ONCE(bytes & 511); WARN_ON_ONCE(disks < RAID6_MIN_DISKS);
static_call(raid6_gen_syndrome_impl)(disks, bytes, ptrs);}EXPORT_SYMBOL_GPL(raid6_gen_syndrome);
/** * raid6_xor_syndrome - update RAID6 P/Q parity * @disks: number of "disks" to operate on including parity * @start: first index into @disk to update * @stop: last index into @disk to update * @bytes: length in bytes of each vector * @ptrs: @disks size array of memory pointers * * Update @bytes worth of RAID6 P and Q parity in @ptrs[@disks - 2] and * @ptrs[@disks - 1] respectively for the memory pointed to by * @ptrs[@start..@stop]. * * This is used to update parity in place using the following sequence: * * 1) call raid6_xor_syndrome(disk, start, stop, ...) for the existing data. * 2) update the the data in @ptrs[@start..@stop]. * 3) call raid6_xor_syndrome(disk, start, stop, ...) for the new data. * * Data between @start and @stop that is not changed should be filled * with a pointer to the kernel zero page. * * @disks must be at least 4, and the memory pointed to by each member of @ptrs * must be at least 64-byte aligned. @bytes must be non-zero and a multiple of * 512. @stop must be larger or equal to @start. */void raid6_xor_syndrome(int disks, int start, int stop, size_t bytes, void **ptrs){ WARN_ON_ONCE(!in_task() || irqs_disabled() || softirq_count()); WARN_ON_ONCE(bytes & 511); WARN_ON_ONCE(disks < RAID6_MIN_DISKS); WARN_ON_ONCE(stop < start);
static_call(raid6_xor_syndrome_impl)(disks, start, stop, bytes, ptrs);}EXPORT_SYMBOL_GPL(raid6_xor_syndrome);
/* * raid6_can_xor_syndrome - check if raid6_xor_syndrome() can be used * * Returns %true if raid6_can_xor_syndrome() can be used, else %false. */bool raid6_can_xor_syndrome(void){ return !!static_call_query(raid6_xor_syndrome_impl);}EXPORT_SYMBOL_GPL(raid6_can_xor_syndrome);
/** * raid6_recov_2data - recover two missing data disks * @disks: number of "disks" to operate on including parity * @bytes: length in bytes of each vector * @faila: first failed data disk index * @failb: second failed data disk index * @ptrs: @disks size array of memory pointers * * Rebuild @bytes of missing data in @ptrs[@faila] and @ptrs[@failb] from the * data in the remaining disks and the two parities pointed to by the other * indices between 0 and @disks - 1 in @ptrs. @disks includes the data disks * and the two parities. @faila must be smaller than @failb. * * Memory pointed to by each pointer in @ptrs must be page aligned and is * limited to %PAGE_SIZE. */void raid6_recov_2data(int disks, size_t bytes, int faila, int failb, void **ptrs){ WARN_ON_ONCE(!in_task() || irqs_disabled() || softirq_count()); WARN_ON_ONCE(bytes & 511); WARN_ON_ONCE(bytes > PAGE_SIZE); WARN_ON_ONCE(failb <= faila);
static_call(raid6_recov_2data_impl)(disks, bytes, faila, failb, ptrs);}EXPORT_SYMBOL_GPL(raid6_recov_2data);
/** * raid6_recov_datap - recover a missing data disk and missing P-parity * @disks: number of "disks" to operate on including parity * @bytes: length in bytes of each vector * @faila: failed data disk index * @ptrs: @disks size array of memory pointers * * Rebuild @bytes of missing data in @ptrs[@faila] and the missing P-parity in * @ptrs[@disks - 2] from the data in the remaining disks and the Q-parity * pointed to by the other indices between 0 and @disks - 1 in @ptrs. @disks * includes the data disks and the two parities. * * Memory pointed to by each pointer in @ptrs must be page aligned and is * limited to %PAGE_SIZE. */void raid6_recov_datap(int disks, size_t bytes, int faila, void **ptrs){ WARN_ON_ONCE(!in_task() || irqs_disabled() || softirq_count()); WARN_ON_ONCE(bytes & 511); WARN_ON_ONCE(bytes > PAGE_SIZE);
static_call(raid6_recov_datap_impl)(disks, bytes, faila, ptrs);}EXPORT_SYMBOL_GPL(raid6_recov_datap);
#define RAID6_TIME_JIFFIES_LG2 4#define RAID6_TEST_DISKS 8
static int raid6_choose_gen(void *(*const dptrs)[RAID6_TEST_DISKS], const int disks){ /* work on the second half of the disks */ int start = (disks >> 1) - 1, stop = disks - 3; const struct raid6_calls *best = NULL; unsigned long bestgenperf = 0; unsigned int i;
for (i = 0; i < raid6_nr_algos; i++) { const struct raid6_calls *algo = raid6_algos[i]; unsigned long perf = 0, j0, j1;
preempt_disable(); j0 = jiffies; while ((j1 = jiffies) == j0) cpu_relax(); while (time_before(jiffies, j1 + (1<<RAID6_TIME_JIFFIES_LG2))) { algo->gen_syndrome(disks, PAGE_SIZE, *dptrs); perf++; } preempt_enable();
if (perf > bestgenperf) { bestgenperf = perf; best = algo; } pr_info("raid6: %-8s gen() %5ld MB/s\n", algo->name, (perf * HZ * (disks-2)) >> (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2)); }
if (!best) { pr_err("raid6: Yikes! No algorithm found!\n"); return -EINVAL; }
static_call_update(raid6_gen_syndrome_impl, best->gen_syndrome); static_call_update(raid6_xor_syndrome_impl, best->xor_syndrome);
pr_info("raid6: using algorithm %s gen() %ld MB/s\n", best->name, (bestgenperf * HZ * (disks - 2)) >> (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
if (best->xor_syndrome) { unsigned long perf = 0, j0, j1;
preempt_disable(); j0 = jiffies; while ((j1 = jiffies) == j0) cpu_relax(); while (time_before(jiffies, j1 + (1 << RAID6_TIME_JIFFIES_LG2))) { best->xor_syndrome(disks, start, stop, PAGE_SIZE, *dptrs); perf++; } preempt_enable();
pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n", (perf * HZ * (disks - 2)) >> (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1)); }
return 0;}
/* Try to pick the best algorithm *//* This code uses the gfmul table as convenient data set to abuse */
static int __init raid6_select_algo(void){ const int disks = RAID6_TEST_DISKS; char *disk_ptr, *p; void *dptrs[RAID6_TEST_DISKS]; int i, cycle; int error;
if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK) || raid6_nr_algos == 1) { pr_info("raid6: skipped pq benchmark and selected %s\n", raid6_algos[raid6_nr_algos - 1]->name); static_call_update(raid6_gen_syndrome_impl, raid6_algos[raid6_nr_algos - 1]->gen_syndrome); static_call_update(raid6_xor_syndrome_impl, raid6_algos[raid6_nr_algos - 1]->xor_syndrome); return 0; }
/* prepare the buffer and fill it circularly with gfmul table */ disk_ptr = kmalloc(PAGE_SIZE * RAID6_TEST_DISKS, GFP_KERNEL); if (!disk_ptr) { pr_err("raid6: Yikes! No memory available.\n"); return -ENOMEM; }
p = disk_ptr; for (i = 0; i < disks; i++) dptrs[i] = p + PAGE_SIZE * i;
cycle = ((disks - 2) * PAGE_SIZE) / 65536; for (i = 0; i < cycle; i++) { memcpy(p, raid6_gfmul, 65536); p += 65536; }
if ((disks - 2) * PAGE_SIZE % 65536) memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
/* select raid gen_syndrome function */ error = raid6_choose_gen(&dptrs, disks);
kfree(disk_ptr);
return error;}
/* * Register a RAID6 P/Q generation algorithm. The most optimized/unrolled * implementation should be registered last so it will be selected when the * boot-time benchmark is disabled. */void __init raid6_algo_add(const struct raid6_calls *algo){ if (WARN_ON_ONCE(raid6_nr_algos == RAID6_MAX_ALGOS)) return; raid6_algos[raid6_nr_algos++] = algo;}
void __init raid6_algo_add_default(void){ raid6_algo_add(&raid6_intx1); raid6_algo_add(&raid6_intx2); raid6_algo_add(&raid6_intx4); raid6_algo_add(&raid6_intx8);}
void __init raid6_recov_algo_add(const struct raid6_recov_calls *algo){ if (WARN_ON_ONCE(raid6_recov_algo)) return; raid6_recov_algo = algo;}
#ifdef CONFIG_RAID6_PQ_ARCH#include "pq_arch.h"#elsestatic inline void arch_raid6_init(void){ raid6_algo_add_default();}#endif /* CONFIG_RAID6_PQ_ARCH */
static int __init raid6_init(void){ /* * Architectures providing arch_raid6_init must add all PQ generation * algorithms they want to consider in arch_raid6_init(), including * the generic ones using raid6_algo_add_default() if wanted. */ arch_raid6_init();
/* * Architectures don't have to set a recovery algorithm, we'll just pick * the generic integer one if none was set. */ if (!raid6_recov_algo) raid6_recov_algo = &raid6_recov_intx1; static_call_update(raid6_recov_2data_impl, raid6_recov_algo->data2); static_call_update(raid6_recov_datap_impl, raid6_recov_algo->datap); pr_info("raid6: using %s recovery algorithm\n", raid6_recov_algo->name);
return raid6_select_algo();}
static void __exit raid6_exit(void){}
subsys_initcall(raid6_init);module_exit(raid6_exit);MODULE_LICENSE("GPL");MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
#if IS_ENABLED(CONFIG_RAID6_PQ_KUNIT_TEST)const struct raid6_calls *raid6_algo_find(unsigned int idx){ if (idx >= raid6_nr_algos) { /* * Always include the simplest generic integer implementation in * the unit tests as a baseline. */ if (idx == raid6_nr_algos && raid6_algos[0] != &raid6_intx1) return &raid6_intx1; return NULL; } return raid6_algos[idx];}EXPORT_SYMBOL_IF_KUNIT(raid6_algo_find);
const struct raid6_recov_calls *raid6_recov_algo_find(unsigned int idx){ switch (idx) { case 0: /* always test the generic integer implementation */ return &raid6_recov_intx1; case 1: /* test the optimized implementation if there is one */ if (raid6_recov_algo != &raid6_recov_intx1) return raid6_recov_algo; return NULL; default: return NULL; }}EXPORT_SYMBOL_IF_KUNIT(raid6_recov_algo_find);#endif /* CONFIG_RAID6_PQ_KUNIT_TEST */