path: root/fs/exofs/ore_raid.c

/*
 * Copyright (C) 2011
 * Boaz Harrosh <ooo@electrozaur.com>
 *
 * This file is part of the objects raid engine (ore).
 *
 * It is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * You should have received a copy of the GNU General Public License
 * along with "ore". If not, write to the Free Software Foundation, Inc:
 *	"Free Software Foundation <info@fsf.org>"
 */

#include <linux/gfp.h>
#include <linux/async_tx.h>

#include "ore_raid.h"

#undef ORE_DBGMSG2
#define ORE_DBGMSG2 ORE_DBGMSG

static struct page *_raid_page_alloc(void)
{
	return alloc_page(GFP_KERNEL);
}

static void _raid_page_free(struct page *p)
{
	__free_page(p);
}

/* This struct is forward declare in ore_io_state, but is private to here.
 * It is put on ios->sp2d for RAID5/6 writes only. See _gen_xor_unit.
 *
 * __stripe_pages_2d is a 2d array of pages, and it is also a corner turn.
 * Ascending page index access is sp2d(p-minor, c-major). But storage is
 * sp2d[p-minor][c-major], so it can be properlly presented to the async-xor
 * API.
 */
struct __stripe_pages_2d {
	/* Cache some hot path repeated calculations */
	unsigned parity;
	unsigned data_devs;
	unsigned pages_in_unit;

	bool needed ;

	/* Array size is pages_in_unit (layout->stripe_unit / PAGE_SIZE) */
	struct __1_page_stripe {
		bool alloc;
		unsigned write_count;
		struct async_submit_ctl submit;
		struct dma_async_tx_descriptor *tx;

		/* The size of this array is data_devs + parity */
		struct page **pages;
		struct page **scribble;
		/* bool array, size of this array is data_devs */
		char *page_is_read;
	} _1p_stripes[];
};

/* This can get bigger then a page. So support multiple page allocations
 * _sp2d_free should be called even if _sp2d_alloc fails (by returning
 * none-zero).
 */
static int _sp2d_alloc(unsigned pages_in_unit, unsigned group_width,
		       unsigned parity, struct __stripe_pages_2d **psp2d)
{
	struct __stripe_pages_2d *sp2d;
	unsigned data_devs = group_width - parity;
	struct _alloc_all_bytes {
		struct __alloc_stripe_pages_2d {
			struct __stripe_pages_2d sp2d;
			struct __1_page_stripe _1p_stripes[pages_in_unit];
		} __asp2d;
		struct __alloc_1p_arrays {
			struct page *pages[group_width];
			struct page *scribble[group_width];
			char page_is_read[data_devs];
		} __a1pa[pages_in_unit];
	} *_aab;
	struct __alloc_1p_arrays *__a1pa;
	struct __alloc_1p_arrays *__a1pa_end;
	const unsigned sizeof__a1pa = sizeof(_aab->__a1pa[0]);
	unsigned num_a1pa, alloc_size, i;

	/* FIXME: check these numbers in ore_verify_layout */
	BUG_ON(sizeof(_aab->__asp2d) > PAGE_SIZE);
	BUG_ON(sizeof__a1pa > PAGE_SIZE);

	if (sizeof(*_aab) > PAGE_SIZE) {
		num_a1pa = (PAGE_SIZE - sizeof(_aab->__asp2d)) / sizeof__a1pa;
		alloc_size = sizeof(_aab->__asp2d) + sizeof__a1pa * num_a1pa;
	} else {
		num_a1pa = pages_in_unit;
		alloc_size = sizeof(*_aab);
	}

	_aab = kzalloc(alloc_size, GFP_KERNEL);
	if (unlikely(!_aab)) {
		ORE_DBGMSG("!! Failed to alloc sp2d size=%d\n", alloc_size);
		return -ENOMEM;
	}

	sp2d = &_aab->__asp2d.sp2d;
	*psp2d = sp2d; /* From here Just call _sp2d_free */

	__a1pa = _aab->__a1pa;
	__a1pa_end = __a1pa + num_a1pa;

	for (i = 0; i < pages_in_unit; ++i) {
		if (unlikely(__a1pa >= __a1pa_end)) {
			num_a1pa = min_t(unsigned, PAGE_SIZE / sizeof__a1pa,
							pages_in_unit - i);

			__a1pa = kcalloc(num_a1pa, sizeof__a1pa, GFP_KERNEL);
			if (unlikely(!__a1pa)) {
				ORE_DBGMSG("!! Failed to _alloc_1p_arrays=%d\n",
					   num_a1pa);
				return -ENOMEM;
			}
			__a1pa_end = __a1pa + num_a1pa;
			/* First *pages is marked for kfree of the buffer */
			sp2d->_1p_stripes[i].alloc = true;
		}

		sp2d->_1p_stripes[i].pages = __a1pa->pages;
		sp2d->_1p_stripes[i].scribble = __a1pa->scribble ;
		sp2d->_1p_stripes[i].page_is_read = __a1pa->page_is_read;
		++__a1pa;
	}

	sp2d->parity = parity;
	sp2d->data_devs = data_devs;
	sp2d->pages_in_unit = pages_in_unit;
	return 0;
}

static void _sp2d_reset(struct __stripe_pages_2d *sp2d,
			const struct _ore_r4w_op *r4w, void *priv)
{
	unsigned data_devs = sp2d->data_devs;
	unsigned group_width = data_devs + sp2d->parity;
	int p, c;

	if (!sp2d->needed)
		return;

	for (c = data_devs - 1; c >= 0; --c)
		for (p = sp2d->pages_in_unit - 1; p >= 0; --p) {
			struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

			if (_1ps->page_is_read[c]) {
				struct page *page = _1ps->pages[c];

				r4w->put_page(priv, page);
				_1ps->page_is_read[c] = false;
			}
		}

	for (p = 0; p < sp2d->pages_in_unit; p++) {
		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];

		memset(_1ps->pages, 0, group_width * sizeof(*_1ps->pages));
		_1ps->write_count = 0;
		_1ps->tx = NULL;
	}

	sp2d->needed = false;
}

static void _sp2d_free(struct __stripe_pages_2d *sp2d)
{
	unsigned i;

	if (!sp2d)
		return;

	for (i = 0; i < sp2d->pages_in_unit; ++i) {
		if (sp2d->_1p_stripes[i].alloc)
			kfree(sp2d->_1p_stripes[i].pages);
	}

	kfree(sp2d);
}

static unsigned _sp2d_min_pg(struct __stripe_pages_2d *sp2d)
{
	unsigned p;

	for (p = 0; p < sp2d->pages_in_unit; p++) {
		struct __1_page_stripe