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ore: Support for raid 6

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This simple patch adds support for raid6 to the ORE.
Most operations and calculations where already for the general
case. Only things left:
* call async_gen_syndrome() in the case of raid6
  (NOTE that the raid6 math is the one supported by the Linux Kernel
   see: crypto/async_tx/async_pq.c)
* call _ore_add_parity_unit() twice with only last call generating
  the redundancy pages.

* Fix couple BUGS in old code
  a. In reads when parity==2 it can happen that per_dev->length=0
     but per_dev->offset was set and adjusted by _ore_add_sg_seg().
     Don't let it be overwritten.
  b. The all 'cur_comp > starting_dev' thing to determine if:
       "per_dev->offset is in the current stripe number or the
       next one."
     Was a complete raid5/4 accident. When parity==2 this is not
     at all true usually. All we need to do is increment si->ob_offset
     once we pass by the first parity device.
     (This also greatly simplifies the code, amen)
  c. Calculation of si->dev rotation can overflow when parity==2.

* Then last enable raid6 in ore_verify_layout()

I want to deeply thank Daniel Gryniewicz who found first all the
bugs in the old raid code, and inspired these patches:
	Inspired-by Daniel Gryniewicz <dang@linuxbox.com>

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
This commit is contained in:
Boaz Harrosh
2014-05-22 14:48:15 +03:00
parent 455682ce54
commit ce5d36aac2
4 changed files with 80 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
fs/exofs/ore_raid.c
View File

@@ -218,20 +218,28 @@ static unsigned _sp2d_max_pg(struct __stripe_pages_2d *sp2d)
static void _gen_xor_unit(struct __stripe_pages_2d *sp2d)
{
unsigned p;
unsigned tx_flags = ASYNC_TX_ACK;
if (sp2d->parity == 1)
tx_flags |= ASYNC_TX_XOR_ZERO_DST;
for (p = 0; p < sp2d->pages_in_unit; p++) {
struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
if (!_1ps->write_count)
continue;
init_async_submit(&_1ps->submit,
ASYNC_TX_XOR_ZERO_DST | ASYNC_TX_ACK,
init_async_submit(&_1ps->submit, tx_flags,
NULL, NULL, NULL, (addr_conv_t *)_1ps->scribble);
/* TODO: raid6 */
_1ps->tx = async_xor(_1ps->pages[sp2d->data_devs], _1ps->pages,
0, sp2d->data_devs, PAGE_SIZE,
&_1ps->submit);
if (sp2d->parity == 1)
_1ps->tx = async_xor(_1ps->pages[sp2d->data_devs],
_1ps->pages, 0, sp2d->data_devs,
PAGE_SIZE, &_1ps->submit);
else /* parity == 2 */
_1ps->tx = async_gen_syndrome(_1ps->pages, 0,
sp2d->data_devs + sp2d->parity,
PAGE_SIZE, &_1ps->submit);
}
for (p = 0; p < sp2d->pages_in_unit; p++) {
@@ -616,7 +624,7 @@ static int _read_4_write_execute(struct ore_io_state *ios)
int _ore_add_parity_unit(struct ore_io_state *ios,
struct ore_striping_info *si,
struct ore_per_dev_state *per_dev,
unsigned cur_len)
unsigned cur_len, bool do_xor)
{
if (ios->reading) {
if (per_dev->cur_sg >= ios->sgs_per_dev) {
@@ -641,9 +649,11 @@ int _ore_add_parity_unit(struct ore_io_state *ios,
/* If first stripe, Read in all read4write pages
* (if needed) before we calculate the first parity.
*/
_read_4_write_first_stripe(ios);
if (do_xor)
_read_4_write_first_stripe(ios);
}
if (!cur_len) /* If last stripe r4w pages of last stripe */
if (!cur_len && do_xor)
/* If last stripe r4w pages of last stripe */
_read_4_write_last_stripe(ios);
_read_4_write_execute(ios);
@@ -655,7 +665,7 @@ int _ore_add_parity_unit(struct ore_io_state *ios,
++(ios->cur_par_page);
}
BUG_ON(si->cur_comp != sp2d->data_devs);
BUG_ON(si->cur_comp < sp2d->data_devs);
BUG_ON(si->cur_pg + num_pages > sp2d->pages_in_unit);
ret = _ore_add_stripe_unit(ios, &array_start, 0, pages,
@@ -663,9 +673,10 @@ int _ore_add_parity_unit(struct ore_io_state *ios,
if (unlikely(ret))
return ret;
/* TODO: raid6 if (last_parity_dev) */
_gen_xor_unit(sp2d);
_sp2d_reset(sp2d, ios->r4w, ios->private);
if (do_xor) {
_gen_xor_unit(sp2d);
_sp2d_reset(sp2d, ios->r4w, ios->private);
}
}
return 0;
}