Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 756 insertions, 0 deletions

diff --git a/fs/exofs/ore_raid.c b/fs/exofs/ore_raid.c
new file mode 100644
index 000000000..199590f36
--- /dev/null
+++ b/fs/exofs/ore_raid.c
@@ -0,0 +1,756 @@
+/*
+ * 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;
+
+	/*
+	 * Desired allocation layout is, though when larger than PAGE_SIZE,
+	 * each struct __alloc_1p_arrays is separately allocated:
+
+	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;
+
+	*/
+
+	char *__a1pa;
+	char *__a1pa_end;
+
+	const size_t sizeof_stripe_pages_2d =
+		sizeof(struct __stripe_pages_2d) +
+		sizeof(struct __1_page_stripe) * pages_in_unit;
+	const size_t sizeof__a1pa =
+		ALIGN(sizeof(struct page *) * (2 * group_width) + data_devs,
+		      sizeof(void *));
+	const size_t sizeof__a1pa_arrays = sizeof__a1pa * pages_in_unit;
+	const size_t alloc_total = sizeof_stripe_pages_2d +
+				   sizeof__a1pa_arrays;
+
+	unsigned num_a1pa, alloc_size, i;
+
+	/* FIXME: check these numbers in ore_verify_layout */
+	BUG_ON(sizeof_stripe_pages_2d > PAGE_SIZE);
+	BUG_ON(sizeof__a1pa > PAGE_SIZE);
+
+	/*
+	 * If alloc_total would be larger than PAGE_SIZE, only allocate
+	 * as many a1pa items as would fill the rest of the page, instead
+	 * of the full pages_in_unit count.
+	 */
+	if (alloc_total > PAGE_SIZE) {
+		num_a1pa = (PAGE_SIZE - sizeof_stripe_pages_2d) / sizeof__a1pa;
+		alloc_size = sizeof_stripe_pages_2d + sizeof__a1pa * num_a1pa;
+	} else {
+		num_a1pa = pages_in_unit;
+		alloc_size = alloc_total;
+	}
+
+	*psp2d = sp2d = kzalloc(alloc_size, GFP_KERNEL);
+	if (unlikely(!sp2d)) {
+		ORE_DBGMSG("!! Failed to alloc sp2d size=%d\n", alloc_size);
+		return -ENOMEM;
+	}
+	/* From here Just call _sp2d_free */
+
+	/* Find start of a1pa area. */
+	__a1pa = (char *)sp2d + sizeof_stripe_pages_2d;
+	/* Find end of the _allocated_ a1pa area. */
+	__a1pa_end = __a1pa + alloc_size;
+
+	/* Allocate additionally needed a1pa items in PAGE_SIZE chunks. */
+	for (i = 0; i < pages_in_unit; ++i) {
+		struct __1_page_stripe *stripe = &sp2d->_1p_stripes[i];
+
+		if (unlikely(__a1pa >= __a1pa_end)) {
+			num_a1pa = min_t(unsigned, PAGE_SIZE / sizeof__a1pa,
+							pages_in_unit - i);
+			alloc_size = sizeof__a1pa * num_a1pa;
+
+			__a1pa = kzalloc(alloc_size, GFP_KERNEL);
+			if (unlikely(!__a1pa)) {
+				ORE_DBGMSG("!! Failed to _alloc_1p_arrays=%d\n",
+					   num_a1pa);
+				return -ENOMEM;
+			}
+			__a1pa_end = __a1pa + alloc_size;
+			/* First *pages is marked for kfree of the buffer */
+			stripe->alloc = true;
+		}
+
+		/*
+		 * Attach all _lp_stripes pointers to the allocation for
+		 * it which was either part of the original PAGE_SIZE
+		 * allocation or the subsequent allocation in this loop.
+		 */
+		stripe->pages = (void *)__a1pa;
+		stripe->scribble = stripe->pages + group_width;
+		stripe->page_is_read = (char *)stripe->scribble + group_width;
+		__a1pa += sizeof__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 *_1ps = &sp2d->_1p_stripes[p];
+
+		if (_1ps->write_count)
+			return p;
+	}
+
+	return ~0;
+}
+
+static unsigned _sp2d_max_pg(struct __stripe_pages_2d *sp2d)
+{
+	int p;
+
+	for (p = sp2d->pages_in_unit - 1; p >= 0; --p) {
+		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
+
+		if (_1ps->write_count)
+			return p;
+	}
+
+	return ~0;
+}
+
+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, tx_flags,
+			NULL, NULL, NULL, (addr_conv_t *)_1ps->scribble);
+
+		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++) {
+		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
+		/* NOTE: We wait for HW synchronously (I don't have such HW
+		 * to test with.) Is parallelism needed with today's multi
+		 * cores?
+		 */
+		async_tx_issue_pending(_1ps->tx);
+	}
+}
+
+void _ore_add_stripe_page(struct __stripe_pages_2d *sp2d,
+		       struct ore_striping_info *si, struct page *page)
+{
+	struct __1_page_stripe *_1ps;
+
+	sp2d->needed = true;
+
+	_1ps = &sp2d->_1p_stripes[si->cur_pg];
+	_1ps->pages[si->cur_comp] = page;
+	++_1ps->write_count;
+
+	si->cur_pg = (si->cur_pg + 1) % sp2d->pages_in_unit;
+	/* si->cur_comp is advanced outside at main loop */
+}
+
+void _ore_add_sg_seg(struct ore_per_dev_state *per_dev, unsigned cur_len,
+		     bool not_last)
+{
+	struct osd_sg_entry *sge;
+
+	ORE_DBGMSG("dev=%d cur_len=0x%x not_last=%d cur_sg=%d "
+		     "offset=0x%llx length=0x%x last_sgs_total=0x%x\n",
+		     per_dev->dev, cur_len, not_last, per_dev->cur_sg,
+		     _LLU(per_dev->offset), per_dev->length,
+		     per_dev->last_sgs_total);
+
+	if (!per_dev->cur_sg) {
+		sge = per_dev->sglist;
+
+		/* First time we prepare two entries */
+		if (per_dev->length) {
+			++per_dev->cur_sg;
+			sge->offset = per_dev->offset;
+			sge->len = per_dev->length;
+		} else {
+			/* Here the parity is the first unit of this object.
+			 * This happens every time we reach a parity device on
+			 * the same stripe as the per_dev->offset. We need to
+			 * just skip this unit.
+			 */
+			per_dev->offset += cur_len;
+			return;
+		}
+	} else {
+		/* finalize the last one */
+		sge = &per_dev->sglist[per_dev->cur_sg - 1];
+		sge->len = per_dev->length - per_dev->last_sgs_total;
+	}
+
+	if (not_last) {
+		/* Partly prepare the next one */
+		struct osd_sg_entry *next_sge = sge + 1;
+
+		++per_dev->cur_sg;
+		next_sge->offset = sge->offset + sge->len + cur_len;
+		/* Save cur len so we know how mutch was added next time */
+		per_dev->last_sgs_total = per_dev->length;
+		next_sge->len = 0;
+	} else if (!sge->len) {
+		/* Optimize for when the last unit is a parity */
+		--per_dev->cur_sg;
+	}
+}
+
+static int _alloc_read_4_write(struct ore_io_state *ios)
+{
+	struct ore_layout *layout = ios->layout;
+	int ret;
+	/* We want to only read those pages not in cache so worst case
+	 * is a stripe populated with every other page
+	 */
+	unsigned sgs_per_dev = ios->sp2d->pages_in_unit + 2;
+
+	ret = _ore_get_io_state(layout, ios->oc,
+				layout->group_width * layout->mirrors_p1,
+				sgs_per_dev, 0, &ios->ios_read_4_write);
+	return ret;
+}
+
+/* @si contains info of the to-be-inserted page. Update of @si should be
+ * maintained by caller. Specificaly si->dev, si->obj_offset, ...
+ */
+static int _add_to_r4w(struct ore_io_state *ios, struct ore_striping_info *si,
+		       struct page *page, unsigned pg_len)
+{
+	struct request_queue *q;
+	struct ore_per_dev_state *per_dev;
+	struct ore_io_state *read_ios;
+	unsigned first_dev = si->dev - (si->dev %
+			  (ios->layout->group_width * ios->layout->mirrors_p1));
+	unsigned comp = si->dev - first_dev;
+	unsigned added_len;
+
+	if (!ios->ios_read_4_write) {
+		int ret = _alloc_read_4_write(ios);
+
+		if (unlikely(ret))
+			return ret;
+	}
+
+	read_ios = ios->ios_read_4_write;
+	read_ios->numdevs = ios->layout->group_width * ios->layout->mirrors_p1;
+
+	per_dev = &read_ios->per_dev[comp];
+	if (!per_dev->length) {
+		per_dev->bio = bio_kmalloc(GFP_KERNEL,
+					   ios->sp2d->pages_in_unit);
+		if (unlikely(!per_dev->bio)) {
+			ORE_DBGMSG("Failed to allocate BIO size=%u\n",
+				     ios->sp2d->pages_in_unit);
+			return -ENOMEM;
+		}
+		per_dev->offset = si->obj_offset;
+		per_dev->dev = si->dev;
+	} else if (si->obj_offset != (per_dev->offset + per_dev->length)) {
+		u64 gap = si->obj_offset - (per_dev->offset + per_dev->length);
+
+		_ore_add_sg_seg(per_dev, gap, true);
+	}
+	q = osd_request_queue(ore_comp_dev(read_ios->oc, per_dev->dev));
+	added_len = bio_add_pc_page(q, per_dev->bio, page, pg_len,
+				    si->obj_offset % PAGE_SIZE);
+	if (unlikely(added_len != pg_len)) {
+		ORE_DBGMSG("Failed to bio_add_pc_page bi_vcnt=%d\n",
+			      per_dev->bio->bi_vcnt);
+		return -ENOMEM;
+	}
+
+	per_dev->length += pg_len;
+	return 0;
+}
+
+/* read the beginning of an unaligned first page */
+static int _add_to_r4w_first_page(struct ore_io_state *ios, struct page *page)
+{
+	struct ore_striping_info si;
+	unsigned pg_len;
+
+	ore_calc_stripe_info(ios->layout, ios->offset, 0, &si);
+
+	pg_len = si.obj_offset % PAGE_SIZE;
+	si.obj_offset -= pg_len;
+
+	ORE_DBGMSG("offset=0x%llx len=0x%x index=0x%lx dev=%x\n",
+		   _LLU(si.obj_offset), pg_len, page->index, si.dev);
+
+	return _add_to_r4w(ios, &si, page, pg_len);
+}
+
+/* read the end of an incomplete last page */
+static int _add_to_r4w_last_page(struct ore_io_state *ios, u64 *offset)
+{
+	struct ore_striping_info si;
+	struct page *page;
+	unsigned pg_len, p, c;
+
+	ore_calc_stripe_info(ios->layout, *offset, 0, &si);
+
+	p = si.cur_pg;
+	c = si.cur_comp;
+	page = ios->sp2d->_1p_stripes[p].pages[c];
+
+	pg_len = PAGE_SIZE - (si.unit_off % PAGE_SIZE);
+	*offset += pg_len;
+
+	ORE_DBGMSG("p=%d, c=%d next-offset=0x%llx len=0x%x dev=%x par_dev=%d\n",
+		   p, c, _LLU(*offset), pg_len, si.dev, si.par_dev);
+
+	BUG_ON(!page);
+
+	return _add_to_r4w(ios, &si, page, pg_len);
+}
+
+static void _mark_read4write_pages_uptodate(struct ore_io_state *ios, int ret)
+{
+	struct bio_vec *bv;
+	unsigned i, d;
+
+	/* loop on all devices all pages */
+	for (d = 0; d < ios->numdevs; d++) {
+		struct bio *bio = ios->per_dev[d].bio;
+
+		if (!bio)
+			continue;
+
+		bio_for_each_segment_all(bv, bio, i) {
+			struct page *page = bv->bv_page;
+
+			SetPageUptodate(page);
+			if (PageError(page))
+				ClearPageError(page);
+		}
+	}
+}
+
+/* read_4_write is hacked to read the start of the first stripe and/or
+ * the end of the last stripe. If needed, with an sg-gap at each device/page.
+ * It is assumed to be called after the to_be_written pages of the first stripe
+ * are populating ios->sp2d[][]
+ *
+ * NOTE: We call ios->r4w->lock_fn for all pages needed for parity calculations
+ * These pages are held at sp2d[p].pages[c] but with
+ * sp2d[p].page_is_read[c] = true. At _sp2d_reset these pages are
+ * ios->r4w->lock_fn(). The ios->r4w->lock_fn might signal that the page is
+ * @uptodate=true, so we don't need to read it, only unlock, after IO.
+ *
+ * TODO: The read_4_write should calc a need_to_read_pages_count, if bigger then
+ * to-be-written count, we should consider the xor-in-place mode.
+ * need_to_read_pages_count is the actual number of pages not present in cache.
+ * maybe "devs_in_group - ios->sp2d[p].write_count" is a good enough
+ * approximation? In this mode the read pages are put in the empty places of
+ * ios->sp2d[p][*], xor is calculated the same way. These pages are
+ * allocated/freed and don't go through cache
+ */
+static int _read_4_write_first_stripe(struct ore_io_state *ios)
+{
+	struct ore_striping_info read_si;
+	struct __stripe_pages_2d *sp2d = ios->sp2d;
+	u64 offset = ios->si.first_stripe_start;
+	unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;
+
+	if (offset == ios->offset) /* Go to start collect $200 */
+		goto read_last_stripe;
+
+	min_p = _sp2d_min_pg(sp2d);
+	max_p = _sp2d_max_pg(sp2d);
+
+	ORE_DBGMSG("stripe_start=0x%llx ios->offset=0x%llx min_p=%d max_p=%d\n",
+		   offset, ios->offset, min_p, max_p);
+
+	for (c = 0; ; c++) {
+		ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
+		read_si.obj_offset += min_p * PAGE_SIZE;
+		offset += min_p * PAGE_SIZE;
+		for (p = min_p; p <= max_p; p++) {
+			struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
+			struct page **pp = &_1ps->pages[c];
+			bool uptodate;
+
+			if (*pp) {
+				if (ios->offset % PAGE_SIZE)
+					/* Read the remainder of the page */
+					_add_to_r4w_first_page(ios, *pp);
+				/* to-be-written pages start here */
+				goto read_last_stripe;
+			}
+
+			*pp = ios->r4w->get_page(ios->private, offset,
+						 &uptodate);
+			if (unlikely(!*pp))
+				return -ENOMEM;
+
+			if (!uptodate)
+				_add_to_r4w(ios, &read_si, *pp, PAGE_SIZE);
+
+			/* Mark read-pages to be cache_released */
+			_1ps->page_is_read[c] = true;
+			read_si.obj_offset += PAGE_SIZE;
+			offset += PAGE_SIZE;
+		}
+		offset += (sp2d->pages_in_unit - p) * PAGE_SIZE;
+	}
+
+read_last_stripe:
+	return 0;
+}
+
+static int _read_4_write_last_stripe(struct ore_io_state *ios)
+{
+	struct ore_striping_info read_si;
+	struct __stripe_pages_2d *sp2d = ios->sp2d;
+	u64 offset;
+	u64 last_stripe_end;
+	unsigned bytes_in_stripe = ios->si.bytes_in_stripe;
+	unsigned c, p, min_p = sp2d->pages_in_unit, max_p = -1;
+
+	offset = ios->offset + ios->length;
+	if (offset % PAGE_SIZE)
+		_add_to_r4w_last_page(ios, &offset);
+		/* offset will be aligned to next page */
+
+	last_stripe_end = div_u64(offset + bytes_in_stripe - 1, bytes_in_stripe)
+				 * bytes_in_stripe;
+	if (offset == last_stripe_end) /* Optimize for the aligned case */
+		goto read_it;
+
+	ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
+	p = read_si.cur_pg;
+	c = read_si.cur_comp;
+
+	if (min_p == sp2d->pages_in_unit) {
+		/* Didn't do it yet */
+		min_p = _sp2d_min_pg(sp2d);
+		max_p = _sp2d_max_pg(sp2d);
+	}
+
+	ORE_DBGMSG("offset=0x%llx stripe_end=0x%llx min_p=%d max_p=%d\n",
+		   offset, last_stripe_end, min_p, max_p);
+
+	while (offset < last_stripe_end) {
+		struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
+
+		if ((min_p <= p) && (p <= max_p)) {
+			struct page *page;
+			bool uptodate;
+
+			BUG_ON(_1ps->pages[c]);
+			page = ios->r4w->get_page(ios->private, offset,
+						  &uptodate);
+			if (unlikely(!page))
+				return -ENOMEM;
+
+			_1ps->pages[c] = page;
+			/* Mark read-pages to be cache_released */
+			_1ps->page_is_read[c] = true;
+			if (!uptodate)
+				_add_to_r4w(ios, &read_si, page, PAGE_SIZE);
+		}
+
+		offset += PAGE_SIZE;
+		if (p == (sp2d->pages_in_unit - 1)) {
+			++c;
+			p = 0;
+			ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
+		} else {
+			read_si.obj_offset += PAGE_SIZE;
+			++p;
+		}
+	}
+
+read_it:
+	return 0;
+}
+
+static int _read_4_write_execute(struct ore_io_state *ios)
+{
+	struct ore_io_state *ios_read;
+	unsigned i;
+	int ret;
+
+	ios_read = ios->ios_read_4_write;
+	if (!ios_read)
+		return 0;
+
+	/* FIXME: Ugly to signal _sbi_read_mirror that we have bio(s). Change
+	 * to check for per_dev->bio
+	 */
+	ios_read->pages = ios->pages;
+
+	/* Now read these devices */
+	for (i = 0; i < ios_read->numdevs; i += ios_read->layout->mirrors_p1) {
+		ret = _ore_read_mirror(ios_read, i);
+		if (unlikely(ret))
+			return ret;
+	}
+
+	ret = ore_io_execute(ios_read); /* Synchronus execution */
+	if (unlikely(ret)) {
+		ORE_DBGMSG("!! ore_io_execute => %d\n", ret);
+		return ret;
+	}
+
+	_mark_read4write_pages_uptodate(ios_read, ret);
+	ore_put_io_state(ios_read);
+	ios->ios_read_4_write = NULL; /* Might need a reuse at last stripe */
+	return 0;
+}
+
+/* In writes @cur_len means length left. .i.e cur_len==0 is the last parity U */
+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, bool do_xor)
+{
+	if (ios->reading) {
+		if (per_dev->cur_sg >= ios->sgs_per_dev) {
+			ORE_DBGMSG("cur_sg(%d) >= sgs_per_dev(%d)\n" ,
+				per_dev->cur_sg, ios->sgs_per_dev);
+			return -ENOMEM;
+		}
+		_ore_add_sg_seg(per_dev, cur_len, true);
+	} else {
+		struct __stripe_pages_2d *sp2d = ios->sp2d;
+		struct page **pages = ios->parity_pages + ios->cur_par_page;
+		unsigned num_pages;
+		unsigned array_start = 0;
+		unsigned i;
+		int ret;
+
+		si->cur_pg = _sp2d_min_pg(sp2d);
+		num_pages  = _sp2d_max_pg(sp2d) + 1 - si->cur_pg;
+
+		if (!per_dev->length) {
+			per_dev->offset += si->cur_pg * PAGE_SIZE;
+			/* If first stripe, Read in all read4write pages
+			 * (if needed) before we calculate the first parity.
+			 */
+			if (do_xor)
+				_read_4_write_first_stripe(ios);
+		}
+		if (!cur_len && do_xor)
+			/* If last stripe r4w pages of last stripe */
+			_read_4_write_last_stripe(ios);
+		_read_4_write_execute(ios);
+
+		for (i = 0; i < num_pages; i++) {
+			pages[i] = _raid_page_alloc();
+			if (unlikely(!pages[i]))
+				return -ENOMEM;
+
+			++(ios->cur_par_page);
+		}
+
+		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,
+					   per_dev, num_pages * PAGE_SIZE);
+		if (unlikely(ret))
+			return ret;
+
+		if (do_xor) {
+			_gen_xor_unit(sp2d);
+			_sp2d_reset(sp2d, ios->r4w, ios->private);
+		}
+	}
+	return 0;
+}
+
+int _ore_post_alloc_raid_stuff(struct ore_io_state *ios)
+{
+	if (ios->parity_pages) {
+		struct ore_layout *layout = ios->layout;
+		unsigned pages_in_unit = layout->stripe_unit / PAGE_SIZE;
+
+		if (_sp2d_alloc(pages_in_unit, layout->group_width,
+				layout->parity, &ios->sp2d)) {
+			return -ENOMEM;
+		}
+	}
+	return 0;
+}
+
+void _ore_free_raid_stuff(struct ore_io_state *ios)
+{
+	if (ios->sp2d) { /* writing and raid */
+		unsigned i;
+
+		for (i = 0; i < ios->cur_par_page; i++) {
+			struct page *page = ios->parity_pages[i];
+
+			if (page)
+				_raid_page_free(page);
+		}
+		if (ios->extra_part_alloc)
+			kfree(ios->parity_pages);
+		/* If IO returned an error pages might need unlocking */
+		_sp2d_reset(ios->sp2d, ios->r4w, ios->private);
+		_sp2d_free(ios->sp2d);
+	} else {
+		/* Will only be set if raid reading && sglist is big */
+		if (ios->extra_part_alloc)
+			kfree(ios->per_dev[0].sglist);
+	}
+	if (ios->ios_read_4_write)
+		ore_put_io_state(ios->ios_read_4_write);
+}