diff options
author | Qu Wenruo <quwenruo@cn.fujitsu.com> | 2016-09-30 13:04:56 +0800 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2016-12-14 15:06:33 +0100 |
commit | ef67f448c725f8ebc02660067e37911bd6dc8e4c (patch) | |
tree | bd6d9cb82310c40b2cf77a847f064bc2e9f6b526 /raid56.c | |
parent | 144a19145e248513c7a676defad59836830535c6 (diff) |
btrfs-progs: raid56: Introduce new function to calculate raid5 parity or data stripe
Introduce new function raid5_gen_result() to calculate parity or data
stripe.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'raid56.c')
-rw-r--r-- | raid56.c | 63 |
1 files changed, 63 insertions, 0 deletions
@@ -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; +} |