From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([222.73.24.84]:5408 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1758162AbcJYCLZ (ORCPT ); Mon, 24 Oct 2016 22:11:25 -0400 From: Qu Wenruo To: linux-btrfs@vger.kernel.org, dsterba@suse.cz Cc: David Sterba Subject: [PATCH v2 3/4] btrfs-progs: raid56: Introduce new function to calculate raid5 parity or data stripe Date: Tue, 25 Oct 2016 10:11:05 +0800 Message-Id: <20161025021106.30842-3-quwenruo@cn.fujitsu.com> In-Reply-To: <20161025021106.30842-1-quwenruo@cn.fujitsu.com> References: <20161025021106.30842-1-quwenruo@cn.fujitsu.com> MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Introduce new function raid5_gen_result() to calculate parity or data stripe. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- Changelog: v2: None --- disk-io.h | 1 + raid56.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 64 insertions(+) diff --git a/disk-io.h b/disk-io.h index 8ab36aa..245626c 100644 --- a/disk-io.h +++ b/disk-io.h @@ -192,5 +192,6 @@ int write_and_map_eb(struct btrfs_trans_handle *trans, struct btrfs_root *root, /* raid56.c */ void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs); +int raid5_gen_result(int nr_devs, size_t stripe_len, int dest, void **data); #endif diff --git a/raid56.c b/raid56.c index 833df5f..8c79c45 100644 --- a/raid56.c +++ b/raid56.c @@ -26,6 +26,8 @@ #include "kerncompat.h" #include "ctree.h" #include "disk-io.h" +#include "volumes.h" +#include "utils.h" /* * This is the C data type to use @@ -107,3 +109,64 @@ void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs) } } +static void xor_range(char *dst, const char*src, size_t size) +{ + /* Move to DWORD aligned */ + while (size && ((unsigned long)dst & sizeof(unsigned long))) { + *dst++ ^= *src++; + size--; + } + + /* DWORD aligned part */ + while (size >= sizeof(unsigned long)) { + *(unsigned long *)dst ^= *(unsigned long *)src; + src += sizeof(unsigned long); + dst += sizeof(unsigned long); + size -= sizeof(unsigned long); + } + /* Remaining */ + while (size) { + *dst++ ^= *src++; + size--; + } +} + +/* + * Generate desired data/parity stripe for RAID5 + * + * @nr_devs: Total number of devices, including parity + * @stripe_len: Stripe length + * @data: Data, with special layout: + * data[0]: Data stripe 0 + * data[nr_devs-2]: Last data stripe + * data[nr_devs-1]: RAID5 parity + * @dest: To generate which data. should follow above data layout + */ +int raid5_gen_result(int nr_devs, size_t stripe_len, int dest, void **data) +{ + int i; + char *buf = data[dest]; + + /* Validation check */ + if (stripe_len <= 0 || stripe_len != BTRFS_STRIPE_LEN) { + error("invalid parameter for %s", __func__); + return -EINVAL; + } + + if (dest >= nr_devs || nr_devs < 2) { + error("invalid parameter for %s", __func__); + return -EINVAL; + } + /* Shortcut for 2 devs RAID5, which is just RAID1 */ + if (nr_devs == 2) { + memcpy(data[dest], data[1 - dest], stripe_len); + return 0; + } + memset(buf, 0, stripe_len); + for (i = 0; i < nr_devs; i++) { + if (i == dest) + continue; + xor_range(buf, data[i], stripe_len); + } + return 0; +} -- 2.10.1