fs/exofs/ore.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (C) 2005, 2006
  * Avishay Traeger (avishay@gmail.com)
  * Copyright (C) 2008, 2009
  * Boaz Harrosh <bharrosh@panasas.com>
  *
  * This file is part of exofs.
  *
  * exofs is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation.  Since it is based on ext2, and the only
  * valid version of GPL for the Linux kernel is version 2, the only valid
  * version of GPL for exofs is version 2.
  *
  * exofs is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with exofs; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */

 #include <linux/slab.h>
 #include <asm/div64.h>

 #include <scsi/osd_ore.h>

 #define ORE_ERR(fmt, a...) printk(KERN_ERR "ore: " fmt, ##a)

 #ifdef CONFIG_EXOFS_DEBUG
 #define ORE_DBGMSG(fmt, a...) \
 	printk(KERN_NOTICE "ore @%s:%d: " fmt, __func__, __LINE__, ##a)
 #else
 #define ORE_DBGMSG(fmt, a...) \
 	do { if (0) printk(fmt, ##a); } while (0)
 #endif

 /* u64 has problems with printk this will cast it to unsigned long long */
 #define _LLU(x) (unsigned long long)(x)

 #define ORE_DBGMSG2(M...) do {} while (0)
 /* #define ORE_DBGMSG2 ORE_DBGMSG */

 MODULE_AUTHOR("Boaz Harrosh <bharrosh@panasas.com>");
 MODULE_DESCRIPTION("Objects Raid Engine ore.ko");
 MODULE_LICENSE("GPL");

 static u8 *_ios_cred(struct ore_io_state *ios, unsigned index)
 {
 	return ios->comps->comps[index & ios->comps->single_comp].cred;
 }

 static struct osd_obj_id *_ios_obj(struct ore_io_state *ios, unsigned index)
 {
 	return &ios->comps->comps[index & ios->comps->single_comp].obj;
 }

 static struct osd_dev *_ios_od(struct ore_io_state *ios, unsigned index)
 {
 	return ios->comps->ods[index];
 }

 int  ore_get_rw_state(struct ore_layout *layout, struct ore_components *comps,
 		      bool is_reading, u64 offset, u64 length,
 		      struct ore_io_state **pios)
 {
 	struct ore_io_state *ios;

 	/*TODO: Maybe use kmem_cach per sbi of size
 	 * exofs_io_state_size(layout->s_numdevs)
 	 */
 	ios = kzalloc(ore_io_state_size(comps->numdevs), GFP_KERNEL);
 	if (unlikely(!ios)) {
 		ORE_DBGMSG("Failed kzalloc bytes=%d\n",
 			     ore_io_state_size(comps->numdevs));
 		*pios = NULL;
 		return -ENOMEM;
 	}

 	ios->layout = layout;
 	ios->comps = comps;
 	ios->offset = offset;
 	ios->length = length;
 	ios->reading = is_reading;

 	*pios = ios;
 	return 0;
 }
 EXPORT_SYMBOL(ore_get_rw_state);

 int  ore_get_io_state(struct ore_layout *layout, struct ore_components *comps,
 		      struct ore_io_state **ios)
 {
 	return ore_get_rw_state(layout, comps, true, 0, 0, ios);
 }
 EXPORT_SYMBOL(ore_get_io_state);

 void ore_put_io_state(struct ore_io_state *ios)
 {
 	if (ios) {
 		unsigned i;

 		for (i = 0; i < ios->numdevs; i++) {
 			struct ore_per_dev_state *per_dev = &ios->per_dev[i];

 			if (per_dev->or)
 				osd_end_request(per_dev->or);
 			if (per_dev->bio)
 				bio_put(per_dev->bio);
 		}

 		kfree(ios);
 	}
 }
 EXPORT_SYMBOL(ore_put_io_state);

 static void _sync_done(struct ore_io_state *ios, void *p)
 {
 	struct completion *waiting = p;

 	complete(waiting);
 }

 static void _last_io(struct kref *kref)
 {
 	struct ore_io_state *ios = container_of(
 					kref, struct ore_io_state, kref);

 	ios->done(ios, ios->private);
 }

 static void _done_io(struct osd_request *or, void *p)
 {
 	struct ore_io_state *ios = p;

 	kref_put(&ios->kref, _last_io);
 }

 static int ore_io_execute(struct ore_io_state *ios)
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	bool sync = (ios->done == NULL);
 	int i, ret;

 	if (sync) {
 		ios->done = _sync_done;
 		ios->private = &wait;
 	}

 	for (i = 0; i < ios->numdevs; i++) {
 		struct osd_request *or = ios->per_dev[i].or;
 		if (unlikely(!or))
 			continue;

 		ret = osd_finalize_request(or, 0, _ios_cred(ios, i), NULL);
 		if (unlikely(ret)) {
 			ORE_DBGMSG("Failed to osd_finalize_request() => %d\n",
 				     ret);
 			return ret;
 		}
 	}

 	kref_init(&ios->kref);

 	for (i = 0; i < ios->numdevs; i++) {
 		struct osd_request *or = ios->per_dev[i].or;
 		if (unlikely(!or))
 			continue;

 		kref_get(&ios->kref);
 		osd_execute_request_async(or, _done_io, ios);
 	}

 	kref_put(&ios->kref, _last_io);
 	ret = 0;

 	if (sync) {
 		wait_for_completion(&wait);
 		ret = ore_check_io(ios, NULL);
 	}
 	return ret;
 }

 static void _clear_bio(struct bio *bio)
 {
 	struct bio_vec *bv;
 	unsigned i;

 	__bio_for_each_segment(bv, bio, i, 0) {
 		unsigned this_count = bv->bv_len;

 		if (likely(PAGE_SIZE == this_count))
 			clear_highpage(bv->bv_page);
 		else
 			zero_user(bv->bv_page, bv->bv_offset, this_count);
 	}
 }

 int ore_check_io(struct ore_io_state *ios, u64 *resid)
 {
 	enum osd_err_priority acumulated_osd_err = 0;
 	int acumulated_lin_err = 0;
 	int i;

 	for (i = 0; i < ios->numdevs; i++) {
 		struct osd_sense_info osi;
 		struct osd_request *or = ios->per_dev[i].or;
 		int ret;

 		if (unlikely(!or))
 			continue;

 		ret = osd_req_decode_sense(or, &osi);
 		if (likely(!ret))
 			continue;

 		if (OSD_ERR_PRI_CLEAR_PAGES == osi.osd_err_pri) {
 			/* start read offset passed endof file */
 			_clear_bio(ios->per_dev[i].bio);
 			ORE_DBGMSG("start read offset passed end of file "
 				"offset=0x%llx, length=0x%llx\n",
 				_LLU(ios->per_dev[i].offset),
 				_LLU(ios->per_dev[i].length));

 			continue; /* we recovered */
 		}

 		if (osi.osd_err_pri >= acumulated_osd_err) {
 			acumulated_osd_err = osi.osd_err_pri;
 			acumulated_lin_err = ret;
 		}
 	}

 	/* TODO: raid specific residual calculations */
 	if (resid) {
 		if (likely(!acumulated_lin_err))
 			*resid = 0;
 		else
 			*resid = ios->length;
 	}

 	return acumulated_lin_err;
 }
 EXPORT_SYMBOL(ore_check_io);

 /*
  * L - logical offset into the file
  *
  * U - The number of bytes in a stripe within a group
  *
  *	U = stripe_unit * group_width
  *
  * T - The number of bytes striped within a group of component objects
  *     (before advancing to the next group)
  *
  *	T = stripe_unit * group_width * group_depth
  *
  * S - The number of bytes striped across all component objects
  *     before the pattern repeats
  *
  *	S = stripe_unit * group_width * group_depth * group_count
  *
  * M - The "major" (i.e., across all components) stripe number
  *
  *	M = L / S
  *
  * G - Counts the groups from the beginning of the major stripe
  *
  *	G = (L - (M * S)) / T	[or (L % S) / T]
  *
  * H - The byte offset within the group
  *
  *	H = (L - (M * S)) % T	[or (L % S) % T]
  *
  * N - The "minor" (i.e., across the group) stripe number
  *
  *	N = H / U
  *
  * C - The component index coresponding to L
  *
  *	C = (H - (N * U)) / stripe_unit + G * group_width
  *	[or (L % U) / stripe_unit + G * group_width]
  *
  * O - The component offset coresponding to L
  *
  *	O = L % stripe_unit + N * stripe_unit + M * group_depth * stripe_unit
  */
 struct _striping_info {
 	u64 obj_offset;
 	u64 group_length;
 	u64 M; /* for truncate */
 	unsigned dev;
 	unsigned unit_off;
 };

 static void _calc_stripe_info(struct ore_layout *layout, u64 file_offset,
 			      struct _striping_info *si)
 {
 	u32	stripe_unit = layout->stripe_unit;
 	u32	group_width = layout->group_width;
 	u64	group_depth = layout->group_depth;

 	u32	U = stripe_unit * group_width;
 	u64	T = U * group_depth;
 	u64	S = T * layout->group_count;
 	u64	M = div64_u64(file_offset, S);

 	/*
 	G = (L - (M * S)) / T
 	H = (L - (M * S)) % T
 	*/
 	u64	LmodS = file_offset - M * S;
 	u32	G = div64_u64(LmodS, T);
 	u64	H = LmodS - G * T;

 	u32	N = div_u64(H, U);

 	/* "H - (N * U)" is just "H % U" so it's bound to u32 */
 	si->dev = (u32)(H - (N * U)) / stripe_unit + G * group_width;
 	si->dev *= layout->mirrors_p1;

 	div_u64_rem(file_offset, stripe_unit, &si->unit_off);

 	si->obj_offset = si->unit_off + (N * stripe_unit) +
 				  (M * group_depth * stripe_unit);

 	si->group_length = T - H;
 	si->M = M;
 }

 static int _add_stripe_unit(struct ore_io_state *ios,  unsigned *cur_pg,
 		unsigned pgbase, struct ore_per_dev_state *per_dev,
 		int cur_len)
 {
 	unsigned pg = *cur_pg;
 	struct request_queue *q =
 			osd_request_queue(_ios_od(ios, per_dev->dev));

 	per_dev->length += cur_len;

 	if (per_dev->bio == NULL) {
 		unsigned pages_in_stripe = ios->layout->group_width *
 					(ios->layout->stripe_unit / PAGE_SIZE);
 		unsigned bio_size = (ios->nr_pages + pages_in_stripe) /
 						ios->layout->group_width;

 		per_dev->bio = bio_kmalloc(GFP_KERNEL, bio_size);
 		if (unlikely(!per_dev->bio)) {
 			ORE_DBGMSG("Failed to allocate BIO size=%u\n",
 				     bio_size);
 			return -ENOMEM;
 		}
 	}

 	while (cur_len > 0) {
 		unsigned pglen = min_t(unsigned, PAGE_SIZE - pgbase, cur_len);
 		unsigned added_len;

 		BUG_ON(ios->nr_pages <= pg);
 		cur_len -= pglen;

 		added_len = bio_add_pc_page(q, per_dev->bio, ios->pages[pg],
 					    pglen, pgbase);
 		if (unlikely(pglen != added_len))
 			return -ENOMEM;
 		pgbase = 0;
 		++pg;
 	}
 	BUG_ON(cur_len);

 	*cur_pg = pg;
 	return 0;
 }

 static int _prepare_one_group(struct ore_io_state *ios, u64 length,
 			      struct _striping_info *si)
 {
 	unsigned stripe_unit = ios->layout->stripe_unit;
 	unsigned mirrors_p1 = ios->layout->mirrors_p1;
 	unsigned devs_in_group = ios->layout->group_width * mirrors_p1;
 	unsigned dev = si->dev;
 	unsigned first_dev = dev - (dev % devs_in_group);
 	unsigned max_comp = ios->numdevs ? ios->numdevs - mirrors_p1 : 0;
 	unsigned cur_pg = ios->pages_consumed;
 	int ret = 0;

 	while (length) {
 		struct ore_per_dev_state *per_dev = &ios->per_dev[dev];
 		unsigned cur_len, page_off = 0;

 		if (!per_dev->length) {
 			per_dev->dev = dev;
 			if (dev < si->dev) {
 				per_dev->offset = si->obj_offset + stripe_unit -
 								   si->unit_off;
 				cur_len = stripe_unit;
 			} else if (dev == si->dev) {
 				per_dev->offset = si->obj_offset;
 				cur_len = stripe_unit - si->unit_off;
 				page_off = si->unit_off & ~PAGE_MASK;
 				BUG_ON(page_off && (page_off != ios->pgbase));
 			} else { /* dev > si->dev */
 				per_dev->offset = si->obj_offset - si->unit_off;
 				cur_len = stripe_unit;
 			}

 			if (max_comp < dev)
 				max_comp = dev;
 		} else {
 			cur_len = stripe_unit;
 		}
 		if (cur_len >= length)
 			cur_len = length;

 		ret = _add_stripe_unit(ios, &cur_pg, page_off , per_dev,
 				       cur_len);
 		if (unlikely(ret))
 			goto out;

 		dev += mirrors_p1;
 		dev = (dev % devs_in_group) + first_dev;

 		length -= cur_len;
 	}
 out:
 	ios->numdevs = max_comp + mirrors_p1;
 	ios->pages_consumed = cur_pg;
 	return ret;
 }

 static int _prepare_for_striping(struct ore_io_state *ios)
 {
 	u64 length = ios->length;
 	u64 offset = ios->offset;
 	struct _striping_info si;
 	int ret = 0;

 	if (!ios->pages) {
 		if (ios->kern_buff) {
 			struct ore_per_dev_state *per_dev = &ios->per_dev[0];

 			_calc_stripe_info(ios->layout, ios->offset, &si);
 			per_dev->offset = si.obj_offset;
 			per_dev->dev = si.dev;

 			/* no cross device without page array */
 			BUG_ON((ios->layout->group_width > 1) &&
 			       (si.unit_off + ios->length >
 				ios->layout->stripe_unit));
 		}
 		ios->numdevs = ios->layout->mirrors_p1;
 		return 0;
 	}

 	while (length) {
 		_calc_stripe_info(ios->layout, offset, &si);

 		if (length < si.group_length)
 			si.group_length = length;

 		ret = _prepare_one_group(ios, si.group_length, &si);
 		if (unlikely(ret))
 			goto out;

 		offset += si.group_length;
 		length -= si.group_length;
 	}

 out:
 	return ret;
 }

 int ore_create(struct ore_io_state *ios)
 {
 	int i, ret;

 	for (i = 0; i < ios->comps->numdevs; i++) {
 		struct osd_request *or;

 		or = osd_start_request(_ios_od(ios, i), GFP_KERNEL);
 		if (unlikely(!or)) {
 			ORE_ERR("%s: osd_start_request failed\n", __func__);
 			ret = -ENOMEM;
 			goto out;
 		}
 		ios->per_dev[i].or = or;
 		ios->numdevs++;

 		osd_req_create_object(or, _ios_obj(ios, i));
 	}
 	ret = ore_io_execute(ios);

 out:
 	return ret;
 }
 EXPORT_SYMBOL(ore_create);

 int ore_remove(struct ore_io_state *ios)
 {
 	int i, ret;

 	for (i = 0; i < ios->comps->numdevs; i++) {
 		struct osd_request *or;

 		or = osd_start_request(_ios_od(ios, i), GFP_KERNEL);
 		if (unlikely(!or)) {
 			ORE_ERR("%s: osd_start_request failed\n", __func__);
 			ret = -ENOMEM;
 			goto out;
 		}
 		ios->per_dev[i].or = or;
 		ios->numdevs++;

 		osd_req_remove_object(or, _ios_obj(ios, i));
 	}
 	ret = ore_io_execute(ios);

 out:
 	return ret;
 }
 EXPORT_SYMBOL(ore_remove);

 static int _write_mirror(struct ore_io_state *ios, int cur_comp)
 {
 	struct ore_per_dev_state *master_dev = &ios->per_dev[cur_comp];
 	unsigned dev = ios->per_dev[cur_comp].dev;
 	unsigned last_comp = cur_comp + ios->layout->mirrors_p1;
 	int ret = 0;

 	if (ios->pages && !master_dev->length)
 		return 0; /* Just an empty slot */

 	for (; cur_comp < last_comp; ++cur_comp, ++dev) {
 		struct ore_per_dev_state *per_dev = &ios->per_dev[cur_comp];
 		struct osd_request *or;

 		or = osd_start_request(_ios_od(ios, dev), GFP_KERNEL);
 		if (unlikely(!or)) {
 			ORE_ERR("%s: osd_start_request failed\n", __func__);
 			ret = -ENOMEM;
 			goto out;
 		}
 		per_dev->or = or;
 		per_dev->offset = master_dev->offset;

 		if (ios->pages) {
 			struct bio *bio;

 			if (per_dev != master_dev) {
 				bio = bio_kmalloc(GFP_KERNEL,
 						  master_dev->bio->bi_max_vecs);
 				if (unlikely(!bio)) {
 					ORE_DBGMSG(
 					      "Failed to allocate BIO size=%u\n",
 					      master_dev->bio->bi_max_vecs);
 					ret = -ENOMEM;
 					goto out;
 				}

 				__bio_clone(bio, master_dev->bio);
 				bio->bi_bdev = NULL;
 				bio->bi_next = NULL;
 				per_dev->length = master_dev->length;
 				per_dev->bio =  bio;
 				per_dev->dev = dev;
 			} else {
 				bio = master_dev->bio;
 				/* FIXME: bio_set_dir() */
 				bio->bi_rw |= REQ_WRITE;
 			}

 			osd_req_write(or, _ios_obj(ios, dev), per_dev->offset,
 				      bio, per_dev->length);
 			ORE_DBGMSG("write(0x%llx) offset=0x%llx "
 				      "length=0x%llx dev=%d\n",
 				     _LLU(_ios_obj(ios, dev)->id),
 				     _LLU(per_dev->offset),
 				     _LLU(per_dev->length), dev);
 		} else if (ios->kern_buff) {
 			ret = osd_req_write_kern(or, _ios_obj(ios, dev),
 						 per_dev->offset,
 						 ios->kern_buff, ios->length);
 			if (unlikely(ret))
 				goto out;
 			ORE_DBGMSG2("write_kern(0x%llx) offset=0x%llx "
 				      "length=0x%llx dev=%d\n",
 				     _LLU(_ios_obj(ios, dev)->id),
 				     _LLU(per_dev->offset),
 				     _LLU(ios->length), dev);
 		} else {
 			osd_req_set_attributes(or, _ios_obj(ios, dev));
 			ORE_DBGMSG2("obj(0x%llx) set_attributes=%d dev=%d\n",
 				     _LLU(_ios_obj(ios, dev)->id),
 				     ios->out_attr_len, dev);
 		}

 		if (ios->out_attr)
 			osd_req_add_set_attr_list(or, ios->out_attr,
 						  ios->out_attr_len);

 		if (ios->in_attr)
 			osd_req_add_get_attr_list(or, ios->in_attr,
 						  ios->in_attr_len);
 	}

 out:
 	return ret;
 }

 int ore_write(struct ore_io_state *ios)
 {
 	int i;
 	int ret;

 	ret = _prepare_for_striping(ios);
 	if (unlikely(ret))
 		return ret;

 	for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
 		ret = _write_mirror(ios, i);
 		if (unlikely(ret))
 			return ret;
 	}

 	ret = ore_io_execute(ios);
 	return ret;
 }
 EXPORT_SYMBOL(ore_write);

 static int _read_mirror(struct ore_io_state *ios, unsigned cur_comp)
 {
 	struct osd_request *or;
 	struct ore_per_dev_state *per_dev = &ios->per_dev[cur_comp];
 	struct osd_obj_id *obj = _ios_obj(ios, cur_comp);
 	unsigned first_dev = (unsigned)obj->id;

 	if (ios->pages && !per_dev->length)
 		return 0; /* Just an empty slot */

 	first_dev = per_dev->dev + first_dev % ios->layout->mirrors_p1;
 	or = osd_start_request(_ios_od(ios, first_dev), GFP_KERNEL);
 	if (unlikely(!or)) {
 		ORE_ERR("%s: osd_start_request failed\n", __func__);
 		return -ENOMEM;
 	}
 	per_dev->or = or;

 	if (ios->pages) {
 		osd_req_read(or, obj, per_dev->offset,
 				per_dev->bio, per_dev->length);
 		ORE_DBGMSG("read(0x%llx) offset=0x%llx length=0x%llx"
 			     " dev=%d\n", _LLU(obj->id),
 			     _LLU(per_dev->offset), _LLU(per_dev->length),
 			     first_dev);
 	} else if (ios->kern_buff) {
 		int ret = osd_req_read_kern(or, obj, per_dev->offset,
 					    ios->kern_buff, ios->length);
 		ORE_DBGMSG2("read_kern(0x%llx) offset=0x%llx "
 			      "length=0x%llx dev=%d ret=>%d\n",
 			      _LLU(obj->id), _LLU(per_dev->offset),
 			      _LLU(ios->length), first_dev, ret);
 		if (unlikely(ret))
 			return ret;
 	} else {
 		osd_req_get_attributes(or, obj);
 		ORE_DBGMSG2("obj(0x%llx) get_attributes=%d dev=%d\n",
 			      _LLU(obj->id),
 			      ios->in_attr_len, first_dev);
 	}
 	if (ios->out_attr)
 		osd_req_add_set_attr_list(or, ios->out_attr, ios->out_attr_len);

 	if (ios->in_attr)
 		osd_req_add_get_attr_list(or, ios->in_attr, ios->in_attr_len);

 	return 0;
 }

 int ore_read(struct ore_io_state *ios)
 {
 	int i;
 	int ret;

 	ret = _prepare_for_striping(ios);
 	if (unlikely(ret))
 		return ret;

 	for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
 		ret = _read_mirror(ios, i);
 		if (unlikely(ret))
 			return ret;
 	}

 	ret = ore_io_execute(ios);
 	return ret;
 }
 EXPORT_SYMBOL(ore_read);

 int extract_attr_from_ios(struct ore_io_state *ios, struct osd_attr *attr)
 {
 	struct osd_attr cur_attr = {.attr_page = 0}; /* start with zeros */
 	void *iter = NULL;
 	int nelem;

 	do {
 		nelem = 1;
 		osd_req_decode_get_attr_list(ios->per_dev[0].or,
 					     &cur_attr, &nelem, &iter);
 		if ((cur_attr.attr_page == attr->attr_page) &&
 		    (cur_attr.attr_id == attr->attr_id)) {
 			attr->len = cur_attr.len;
 			attr->val_ptr = cur_attr.val_ptr;
 			return 0;
 		}
 	} while (iter);

 	return -EIO;
 }
 EXPORT_SYMBOL(extract_attr_from_ios);

 static int _truncate_mirrors(struct ore_io_state *ios, unsigned cur_comp,
 			     struct osd_attr *attr)
 {
 	int last_comp = cur_comp + ios->layout->mirrors_p1;

 	for (; cur_comp < last_comp; ++cur_comp) {
 		struct ore_per_dev_state *per_dev = &ios->per_dev[cur_comp];
 		struct osd_request *or;

 		or = osd_start_request(_ios_od(ios, cur_comp), GFP_KERNEL);
 		if (unlikely(!or)) {
 			ORE_ERR("%s: osd_start_request failed\n", __func__);
 			return -ENOMEM;
 		}
 		per_dev->or = or;

 		osd_req_set_attributes(or, _ios_obj(ios, cur_comp));
 		osd_req_add_set_attr_list(or, attr, 1);
 	}

 	return 0;
 }

 struct _trunc_info {
 	struct _striping_info si;
 	u64 prev_group_obj_off;
 	u64 next_group_obj_off;

 	unsigned first_group_dev;
 	unsigned nex_group_dev;
 	unsigned max_devs;
 };

 void _calc_trunk_info(struct ore_layout *layout, u64 file_offset,
 		       struct _trunc_info *ti)
 {
 	unsigned stripe_unit = layout->stripe_unit;

 	_calc_stripe_info(layout, file_offset, &ti->si);

 	ti->prev_group_obj_off = ti->si.M * stripe_unit;
 	ti->next_group_obj_off = ti->si.M ? (ti->si.M - 1) * stripe_unit : 0;

 	ti->first_group_dev = ti->si.dev - (ti->si.dev % layout->group_width);
 	ti->nex_group_dev = ti->first_group_dev + layout->group_width;
 	ti->max_devs = layout->group_width * layout->group_count;
 }

 int ore_truncate(struct ore_layout *layout, struct ore_components *comps,
 		   u64 size)
 {
 	struct ore_io_state *ios;
 	struct exofs_trunc_attr {
 		struct osd_attr attr;
 		__be64 newsize;
 	} *size_attrs;
 	struct _trunc_info ti;
 	int i, ret;

 	ret = ore_get_io_state(layout, comps, &ios);
 	if (unlikely(ret))
 		return ret;

 	_calc_trunk_info(ios->layout, size, &ti);

 	size_attrs = kcalloc(ti.max_devs, sizeof(*size_attrs),
 			     GFP_KERNEL);
 	if (unlikely(!size_attrs)) {
 		ret = -ENOMEM;
 		goto out;
 	}

 	ios->numdevs = ios->comps->numdevs;

 	for (i = 0; i < ti.max_devs; ++i) {
 		struct exofs_trunc_attr *size_attr = &size_attrs[i];
 		u64 obj_size;

 		if (i < ti.first_group_dev)
 			obj_size = ti.prev_group_obj_off;
 		else if (i >= ti.nex_group_dev)
 			obj_size = ti.next_group_obj_off;
 		else if (i < ti.si.dev) /* dev within this group */
 			obj_size = ti.si.obj_offset +
 				      ios->layout->stripe_unit - ti.si.unit_off;
 		else if (i == ti.si.dev)
 			obj_size = ti.si.obj_offset;
 		else /* i > ti.dev */
 			obj_size = ti.si.obj_offset - ti.si.unit_off;

 		size_attr->newsize = cpu_to_be64(obj_size);
 		size_attr->attr = g_attr_logical_length;
 		size_attr->attr.val_ptr = &size_attr->newsize;

 		ORE_DBGMSG("trunc(0x%llx) obj_offset=0x%llx dev=%d\n",
 			     _LLU(comps->comps->obj.id), _LLU(obj_size), i);
 		ret = _truncate_mirrors(ios, i * ios->layout->mirrors_p1,
 					&size_attr->attr);
 		if (unlikely(ret))
 			goto out;
 	}
 	ret = ore_io_execute(ios);

 out:
 	kfree(size_attrs);
 	ore_put_io_state(ios);
 	return ret;
 }
 EXPORT_SYMBOL(ore_truncate);

 const struct osd_attr g_attr_logical_length = ATTR_DEF(
 	OSD_APAGE_OBJECT_INFORMATION, OSD_ATTR_OI_LOGICAL_LENGTH, 8);
 EXPORT_SYMBOL(g_attr_logical_length);
	/*
	* Copyright (C) 2005, 2006
	* Avishay Traeger (avishay@gmail.com)
	* Copyright (C) 2008, 2009
	* Boaz Harrosh <bharrosh@panasas.com>
	*
	* This file is part of exofs.
	*
	* exofs is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation. Since it is based on ext2, and the only
	* valid version of GPL for the Linux kernel is version 2, the only valid
	* version of GPL for exofs is version 2.
	*
	* exofs is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with exofs; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	#include <linux/slab.h>
	#include <asm/div64.h>

	#include <scsi/osd_ore.h>

	#define ORE_ERR(fmt, a...) printk(KERN_ERR "ore: " fmt, ##a)

	#ifdef CONFIG_EXOFS_DEBUG
	#define ORE_DBGMSG(fmt, a...) \
	printk(KERN_NOTICE "ore @%s:%d: " fmt, __func__, __LINE__, ##a)
	#else
	#define ORE_DBGMSG(fmt, a...) \
	do { if (0) printk(fmt, ##a); } while (0)
	#endif

	/* u64 has problems with printk this will cast it to unsigned long long */
	#define _LLU(x) (unsigned long long)(x)

	#define ORE_DBGMSG2(M...) do {} while (0)
	/* #define ORE_DBGMSG2 ORE_DBGMSG */

	MODULE_AUTHOR("Boaz Harrosh <bharrosh@panasas.com>");
	MODULE_DESCRIPTION("Objects Raid Engine ore.ko");
	MODULE_LICENSE("GPL");

	static u8 _ios_cred(struct ore_io_state ios, unsigned index)
	{
	return ios->comps->comps[index & ios->comps->single_comp].cred;
	}

	static struct osd_obj_id _ios_obj(struct ore_io_state ios, unsigned index)
	{
	return &ios->comps->comps[index & ios->comps->single_comp].obj;
	}

	static struct osd_dev _ios_od(struct ore_io_state ios, unsigned index)
	{
	return ios->comps->ods[index];
	}

	int ore_get_rw_state(struct ore_layout layout, struct ore_components comps,
	bool is_reading, u64 offset, u64 length,
	struct ore_io_state **pios)
	{
	struct ore_io_state *ios;

	/*TODO: Maybe use kmem_cach per sbi of size
	* exofs_io_state_size(layout->s_numdevs)
	*/
	ios = kzalloc(ore_io_state_size(comps->numdevs), GFP_KERNEL);
	if (unlikely(!ios)) {
	ORE_DBGMSG("Failed kzalloc bytes=%d\n",
	ore_io_state_size(comps->numdevs));
	*pios = NULL;
	return -ENOMEM;
	}

	ios->layout = layout;
	ios->comps = comps;
	ios->offset = offset;
	ios->length = length;
	ios->reading = is_reading;

	*pios = ios;
	return 0;
	}
	EXPORT_SYMBOL(ore_get_rw_state);

	int ore_get_io_state(struct ore_layout layout, struct ore_components comps,
	struct ore_io_state **ios)
	{
	return ore_get_rw_state(layout, comps, true, 0, 0, ios);
	}
	EXPORT_SYMBOL(ore_get_io_state);

	void ore_put_io_state(struct ore_io_state *ios)
	{
	if (ios) {
	unsigned i;

	for (i = 0; i < ios->numdevs; i++) {
	struct ore_per_dev_state *per_dev = &ios->per_dev[i];

	if (per_dev->or)
	osd_end_request(per_dev->or);
	if (per_dev->bio)
	bio_put(per_dev->bio);
	}

	kfree(ios);
	}
	}
	EXPORT_SYMBOL(ore_put_io_state);

	static void _sync_done(struct ore_io_state ios, void p)
	{
	struct completion *waiting = p;

	complete(waiting);
	}

	static void _last_io(struct kref *kref)
	{
	struct ore_io_state *ios = container_of(
	kref, struct ore_io_state, kref);

	ios->done(ios, ios->private);
	}

	static void _done_io(struct osd_request or, void p)
	{
	struct ore_io_state *ios = p;

	kref_put(&ios->kref, _last_io);
	}

	static int ore_io_execute(struct ore_io_state *ios)
	{
	DECLARE_COMPLETION_ONSTACK(wait);
	bool sync = (ios->done == NULL);
	int i, ret;

	if (sync) {
	ios->done = _sync_done;
	ios->private = &wait;
	}

	for (i = 0; i < ios->numdevs; i++) {
	struct osd_request *or = ios->per_dev[i].or;
	if (unlikely(!or))
	continue;

	ret = osd_finalize_request(or, 0, _ios_cred(ios, i), NULL);
	if (unlikely(ret)) {
	ORE_DBGMSG("Failed to osd_finalize_request() => %d\n",
	ret);
	return ret;
	}
	}

	kref_init(&ios->kref);

	for (i = 0; i < ios->numdevs; i++) {
	struct osd_request *or = ios->per_dev[i].or;
	if (unlikely(!or))
	continue;

	kref_get(&ios->kref);
	osd_execute_request_async(or, _done_io, ios);
	}

	kref_put(&ios->kref, _last_io);
	ret = 0;

	if (sync) {
	wait_for_completion(&wait);
	ret = ore_check_io(ios, NULL);
	}
	return ret;
	}

	static void _clear_bio(struct bio *bio)
	{
	struct bio_vec *bv;
	unsigned i;

	__bio_for_each_segment(bv, bio, i, 0) {
	unsigned this_count = bv->bv_len;

	if (likely(PAGE_SIZE == this_count))
	clear_highpage(bv->bv_page);
	else
	zero_user(bv->bv_page, bv->bv_offset, this_count);
	}
	}

	int ore_check_io(struct ore_io_state ios, u64 resid)
	{
	enum osd_err_priority acumulated_osd_err = 0;
	int acumulated_lin_err = 0;
	int i;

	for (i = 0; i < ios->numdevs; i++) {
	struct osd_sense_info osi;
	struct osd_request *or = ios->per_dev[i].or;
	int ret;

	if (unlikely(!or))
	continue;

	ret = osd_req_decode_sense(or, &osi);
	if (likely(!ret))
	continue;

	if (OSD_ERR_PRI_CLEAR_PAGES == osi.osd_err_pri) {
	/* start read offset passed endof file */
	_clear_bio(ios->per_dev[i].bio);
	ORE_DBGMSG("start read offset passed end of file "
	"offset=0x%llx, length=0x%llx\n",
	_LLU(ios->per_dev[i].offset),
	_LLU(ios->per_dev[i].length));

	continue; /* we recovered */
	}

	if (osi.osd_err_pri >= acumulated_osd_err) {
	acumulated_osd_err = osi.osd_err_pri;
	acumulated_lin_err = ret;
	}
	}

	/* TODO: raid specific residual calculations */
	if (resid) {
	if (likely(!acumulated_lin_err))
	*resid = 0;
	else
	*resid = ios->length;
	}

	return acumulated_lin_err;
	}
	EXPORT_SYMBOL(ore_check_io);

	/*
	* L - logical offset into the file
	*
	* U - The number of bytes in a stripe within a group
	*
	* U = stripe_unit * group_width
	*
	* T - The number of bytes striped within a group of component objects
	* (before advancing to the next group)
	*
	* T = stripe_unit * group_width * group_depth
	*
	* S - The number of bytes striped across all component objects
	* before the pattern repeats
	*
	* S = stripe_unit * group_width * group_depth * group_count
	*
	* M - The "major" (i.e., across all components) stripe number
	*
	* M = L / S
	*
	* G - Counts the groups from the beginning of the major stripe
	*
	* G = (L - (M * S)) / T [or (L % S) / T]
	*
	* H - The byte offset within the group
	*
	* H = (L - (M * S)) % T [or (L % S) % T]
	*
	* N - The "minor" (i.e., across the group) stripe number
	*
	* N = H / U
	*
	* C - The component index coresponding to L
	*
	* C = (H - (N * U)) / stripe_unit + G * group_width
	* [or (L % U) / stripe_unit + G * group_width]
	*
	* O - The component offset coresponding to L
	*
	* O = L % stripe_unit + N * stripe_unit + M * group_depth * stripe_unit
	*/
	struct _striping_info {
	u64 obj_offset;
	u64 group_length;
	u64 M; /* for truncate */
	unsigned dev;
	unsigned unit_off;
	};

	static void _calc_stripe_info(struct ore_layout *layout, u64 file_offset,
	struct _striping_info *si)
	{
	u32 stripe_unit = layout->stripe_unit;
	u32 group_width = layout->group_width;
	u64 group_depth = layout->group_depth;

	u32 U = stripe_unit * group_width;
	u64 T = U * group_depth;
	u64 S = T * layout->group_count;
	u64 M = div64_u64(file_offset, S);

	/*
	G = (L - (M * S)) / T
	H = (L - (M * S)) % T
	*/
	u64 LmodS = file_offset - M * S;
	u32 G = div64_u64(LmodS, T);
	u64 H = LmodS - G * T;

	u32 N = div_u64(H, U);

	/* "H - (N * U)" is just "H % U" so it's bound to u32 */
	si->dev = (u32)(H - (N * U)) / stripe_unit + G * group_width;
	si->dev *= layout->mirrors_p1;

	div_u64_rem(file_offset, stripe_unit, &si->unit_off);

	si->obj_offset = si->unit_off + (N * stripe_unit) +
	(M * group_depth * stripe_unit);

	si->group_length = T - H;
	si->M = M;
	}

	static int _add_stripe_unit(struct ore_io_state ios, unsigned cur_pg,
	unsigned pgbase, struct ore_per_dev_state *per_dev,
	int cur_len)
	{
	unsigned pg = *cur_pg;
	struct request_queue *q =
	osd_request_queue(_ios_od(ios, per_dev->dev));

	per_dev->length += cur_len;

	if (per_dev->bio == NULL) {
	unsigned pages_in_stripe = ios->layout->group_width *
	(ios->layout->stripe_unit / PAGE_SIZE);
	unsigned bio_size = (ios->nr_pages + pages_in_stripe) /
	ios->layout->group_width;

	per_dev->bio = bio_kmalloc(GFP_KERNEL, bio_size);
	if (unlikely(!per_dev->bio)) {
	ORE_DBGMSG("Failed to allocate BIO size=%u\n",
	bio_size);
	return -ENOMEM;
	}
	}

	while (cur_len > 0) {
	unsigned pglen = min_t(unsigned, PAGE_SIZE - pgbase, cur_len);
	unsigned added_len;

	BUG_ON(ios->nr_pages <= pg);
	cur_len -= pglen;

	added_len = bio_add_pc_page(q, per_dev->bio, ios->pages[pg],
	pglen, pgbase);
	if (unlikely(pglen != added_len))
	return -ENOMEM;
	pgbase = 0;
	++pg;
	}
	BUG_ON(cur_len);

	*cur_pg = pg;
	return 0;
	}

	static int _prepare_one_group(struct ore_io_state *ios, u64 length,
	struct _striping_info *si)
	{
	unsigned stripe_unit = ios->layout->stripe_unit;
	unsigned mirrors_p1 = ios->layout->mirrors_p1;
	unsigned devs_in_group = ios->layout->group_width * mirrors_p1;
	unsigned dev = si->dev;
	unsigned first_dev = dev - (dev % devs_in_group);
	unsigned max_comp = ios->numdevs ? ios->numdevs - mirrors_p1 : 0;
	unsigned cur_pg = ios->pages_consumed;
	int ret = 0;

	while (length) {
	struct ore_per_dev_state *per_dev = &ios->per_dev[dev];
	unsigned cur_len, page_off = 0;

	if (!per_dev->length) {
	per_dev->dev = dev;
	if (dev < si->dev) {
	per_dev->offset = si->obj_offset + stripe_unit -
	si->unit_off;
	cur_len = stripe_unit;
	} else if (dev == si->dev) {
	per_dev->offset = si->obj_offset;
	cur_len = stripe_unit - si->unit_off;
	page_off = si->unit_off & ~PAGE_MASK;
	BUG_ON(page_off && (page_off != ios->pgbase));
	} else { /* dev > si->dev */
	per_dev->offset = si->obj_offset - si->unit_off;
	cur_len = stripe_unit;
	}

	if (max_comp < dev)
	max_comp = dev;
	} else {
	cur_len = stripe_unit;
	}
	if (cur_len >= length)
	cur_len = length;

	ret = _add_stripe_unit(ios, &cur_pg, page_off , per_dev,
	cur_len);
	if (unlikely(ret))
	goto out;

	dev += mirrors_p1;
	dev = (dev % devs_in_group) + first_dev;

	length -= cur_len;
	}
	out:
	ios->numdevs = max_comp + mirrors_p1;
	ios->pages_consumed = cur_pg;
	return ret;
	}

	static int _prepare_for_striping(struct ore_io_state *ios)
	{
	u64 length = ios->length;
	u64 offset = ios->offset;
	struct _striping_info si;
	int ret = 0;

	if (!ios->pages) {
	if (ios->kern_buff) {
	struct ore_per_dev_state *per_dev = &ios->per_dev[0];

	_calc_stripe_info(ios->layout, ios->offset, &si);
	per_dev->offset = si.obj_offset;
	per_dev->dev = si.dev;

	/* no cross device without page array */
	BUG_ON((ios->layout->group_width > 1) &&
	(si.unit_off + ios->length >
	ios->layout->stripe_unit));
	}
	ios->numdevs = ios->layout->mirrors_p1;
	return 0;
	}

	while (length) {
	_calc_stripe_info(ios->layout, offset, &si);

	if (length < si.group_length)
	si.group_length = length;

	ret = _prepare_one_group(ios, si.group_length, &si);
	if (unlikely(ret))
	goto out;

	offset += si.group_length;
	length -= si.group_length;
	}

	out:
	return ret;
	}

	int ore_create(struct ore_io_state *ios)
	{
	int i, ret;

	for (i = 0; i < ios->comps->numdevs; i++) {
	struct osd_request *or;

	or = osd_start_request(_ios_od(ios, i), GFP_KERNEL);
	if (unlikely(!or)) {
	ORE_ERR("%s: osd_start_request failed\n", __func__);
	ret = -ENOMEM;
	goto out;
	}
	ios->per_dev[i].or = or;
	ios->numdevs++;

	osd_req_create_object(or, _ios_obj(ios, i));
	}
	ret = ore_io_execute(ios);

	out:
	return ret;
	}
	EXPORT_SYMBOL(ore_create);

	int ore_remove(struct ore_io_state *ios)
	{
	int i, ret;

	for (i = 0; i < ios->comps->numdevs; i++) {
	struct osd_request *or;

	or = osd_start_request(_ios_od(ios, i), GFP_KERNEL);
	if (unlikely(!or)) {
	ORE_ERR("%s: osd_start_request failed\n", __func__);
	ret = -ENOMEM;
	goto out;
	}
	ios->per_dev[i].or = or;
	ios->numdevs++;

	osd_req_remove_object(or, _ios_obj(ios, i));
	}
	ret = ore_io_execute(ios);

	out:
	return ret;
	}
	EXPORT_SYMBOL(ore_remove);

	static int _write_mirror(struct ore_io_state *ios, int cur_comp)
	{
	struct ore_per_dev_state *master_dev = &ios->per_dev[cur_comp];
	unsigned dev = ios->per_dev[cur_comp].dev;
	unsigned last_comp = cur_comp + ios->layout->mirrors_p1;
	int ret = 0;

	if (ios->pages && !master_dev->length)
	return 0; /* Just an empty slot */

	for (; cur_comp < last_comp; ++cur_comp, ++dev) {
	struct ore_per_dev_state *per_dev = &ios->per_dev[cur_comp];
	struct osd_request *or;

	or = osd_start_request(_ios_od(ios, dev), GFP_KERNEL);
	if (unlikely(!or)) {
	ORE_ERR("%s: osd_start_request failed\n", __func__);
	ret = -ENOMEM;
	goto out;
	}
	per_dev->or = or;
	per_dev->offset = master_dev->offset;

	if (ios->pages) {
	struct bio *bio;

	if (per_dev != master_dev) {
	bio = bio_kmalloc(GFP_KERNEL,
	master_dev->bio->bi_max_vecs);
	if (unlikely(!bio)) {
	ORE_DBGMSG(
	"Failed to allocate BIO size=%u\n",
	master_dev->bio->bi_max_vecs);
	ret = -ENOMEM;
	goto out;
	}

	__bio_clone(bio, master_dev->bio);
	bio->bi_bdev = NULL;
	bio->bi_next = NULL;
	per_dev->length = master_dev->length;
	per_dev->bio = bio;
	per_dev->dev = dev;
	} else {
	bio = master_dev->bio;
	/* FIXME: bio_set_dir() */
	bio->bi_rw \|= REQ_WRITE;
	}

	osd_req_write(or, _ios_obj(ios, dev), per_dev->offset,
	bio, per_dev->length);
	ORE_DBGMSG("write(0x%llx) offset=0x%llx "
	"length=0x%llx dev=%d\n",
	_LLU(_ios_obj(ios, dev)->id),
	_LLU(per_dev->offset),
	_LLU(per_dev->length), dev);
	} else if (ios->kern_buff) {
	ret = osd_req_write_kern(or, _ios_obj(ios, dev),
	per_dev->offset,
	ios->kern_buff, ios->length);
	if (unlikely(ret))
	goto out;
	ORE_DBGMSG2("write_kern(0x%llx) offset=0x%llx "
	"length=0x%llx dev=%d\n",
	_LLU(_ios_obj(ios, dev)->id),
	_LLU(per_dev->offset),
	_LLU(ios->length), dev);
	} else {
	osd_req_set_attributes(or, _ios_obj(ios, dev));
	ORE_DBGMSG2("obj(0x%llx) set_attributes=%d dev=%d\n",
	_LLU(_ios_obj(ios, dev)->id),
	ios->out_attr_len, dev);
	}

	if (ios->out_attr)
	osd_req_add_set_attr_list(or, ios->out_attr,
	ios->out_attr_len);

	if (ios->in_attr)
	osd_req_add_get_attr_list(or, ios->in_attr,
	ios->in_attr_len);
	}

	out:
	return ret;
	}

	int ore_write(struct ore_io_state *ios)
	{
	int i;
	int ret;

	ret = _prepare_for_striping(ios);
	if (unlikely(ret))
	return ret;

	for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
	ret = _write_mirror(ios, i);
	if (unlikely(ret))
	return ret;
	}

	ret = ore_io_execute(ios);
	return ret;
	}
	EXPORT_SYMBOL(ore_write);

	static int _read_mirror(struct ore_io_state *ios, unsigned cur_comp)
	{
	struct osd_request *or;
	struct ore_per_dev_state *per_dev = &ios->per_dev[cur_comp];
	struct osd_obj_id *obj = _ios_obj(ios, cur_comp);
	unsigned first_dev = (unsigned)obj->id;

	if (ios->pages && !per_dev->length)
	return 0; /* Just an empty slot */

	first_dev = per_dev->dev + first_dev % ios->layout->mirrors_p1;
	or = osd_start_request(_ios_od(ios, first_dev), GFP_KERNEL);
	if (unlikely(!or)) {
	ORE_ERR("%s: osd_start_request failed\n", __func__);
	return -ENOMEM;
	}
	per_dev->or = or;

	if (ios->pages) {
	osd_req_read(or, obj, per_dev->offset,
	per_dev->bio, per_dev->length);
	ORE_DBGMSG("read(0x%llx) offset=0x%llx length=0x%llx"
	" dev=%d\n", _LLU(obj->id),
	_LLU(per_dev->offset), _LLU(per_dev->length),
	first_dev);
	} else if (ios->kern_buff) {
	int ret = osd_req_read_kern(or, obj, per_dev->offset,
	ios->kern_buff, ios->length);
	ORE_DBGMSG2("read_kern(0x%llx) offset=0x%llx "
	"length=0x%llx dev=%d ret=>%d\n",
	_LLU(obj->id), _LLU(per_dev->offset),
	_LLU(ios->length), first_dev, ret);
	if (unlikely(ret))
	return ret;
	} else {
	osd_req_get_attributes(or, obj);
	ORE_DBGMSG2("obj(0x%llx) get_attributes=%d dev=%d\n",
	_LLU(obj->id),
	ios->in_attr_len, first_dev);
	}
	if (ios->out_attr)
	osd_req_add_set_attr_list(or, ios->out_attr, ios->out_attr_len);

	if (ios->in_attr)
	osd_req_add_get_attr_list(or, ios->in_attr, ios->in_attr_len);

	return 0;
	}

	int ore_read(struct ore_io_state *ios)
	{
	int i;
	int ret;

	ret = _prepare_for_striping(ios);
	if (unlikely(ret))
	return ret;

	for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
	ret = _read_mirror(ios, i);
	if (unlikely(ret))
	return ret;
	}

	ret = ore_io_execute(ios);
	return ret;
	}
	EXPORT_SYMBOL(ore_read);

	int extract_attr_from_ios(struct ore_io_state ios, struct osd_attr attr)
	{
	struct osd_attr cur_attr = {.attr_page = 0}; /* start with zeros */
	void *iter = NULL;
	int nelem;

	do {
	nelem = 1;
	osd_req_decode_get_attr_list(ios->per_dev[0].or,
	&cur_attr, &nelem, &iter);
	if ((cur_attr.attr_page == attr->attr_page) &&
	(cur_attr.attr_id == attr->attr_id)) {
	attr->len = cur_attr.len;
	attr->val_ptr = cur_attr.val_ptr;
	return 0;
	}
	} while (iter);

	return -EIO;
	}
	EXPORT_SYMBOL(extract_attr_from_ios);

	static int _truncate_mirrors(struct ore_io_state *ios, unsigned cur_comp,
	struct osd_attr *attr)
	{
	int last_comp = cur_comp + ios->layout->mirrors_p1;

	for (; cur_comp < last_comp; ++cur_comp) {
	struct ore_per_dev_state *per_dev = &ios->per_dev[cur_comp];
	struct osd_request *or;

	or = osd_start_request(_ios_od(ios, cur_comp), GFP_KERNEL);
	if (unlikely(!or)) {
	ORE_ERR("%s: osd_start_request failed\n", __func__);
	return -ENOMEM;
	}
	per_dev->or = or;

	osd_req_set_attributes(or, _ios_obj(ios, cur_comp));
	osd_req_add_set_attr_list(or, attr, 1);
	}

	return 0;
	}

	struct _trunc_info {
	struct _striping_info si;
	u64 prev_group_obj_off;
	u64 next_group_obj_off;

	unsigned first_group_dev;
	unsigned nex_group_dev;
	unsigned max_devs;
	};

	void _calc_trunk_info(struct ore_layout *layout, u64 file_offset,
	struct _trunc_info *ti)
	{
	unsigned stripe_unit = layout->stripe_unit;

	_calc_stripe_info(layout, file_offset, &ti->si);

	ti->prev_group_obj_off = ti->si.M * stripe_unit;
	ti->next_group_obj_off = ti->si.M ? (ti->si.M - 1) * stripe_unit : 0;

	ti->first_group_dev = ti->si.dev - (ti->si.dev % layout->group_width);
	ti->nex_group_dev = ti->first_group_dev + layout->group_width;
	ti->max_devs = layout->group_width * layout->group_count;
	}

	int ore_truncate(struct ore_layout layout, struct ore_components comps,
	u64 size)
	{
	struct ore_io_state *ios;
	struct exofs_trunc_attr {
	struct osd_attr attr;
	__be64 newsize;
	} *size_attrs;
	struct _trunc_info ti;
	int i, ret;

	ret = ore_get_io_state(layout, comps, &ios);
	if (unlikely(ret))
	return ret;

	_calc_trunk_info(ios->layout, size, &ti);

	size_attrs = kcalloc(ti.max_devs, sizeof(*size_attrs),
	GFP_KERNEL);
	if (unlikely(!size_attrs)) {
	ret = -ENOMEM;
	goto out;
	}

	ios->numdevs = ios->comps->numdevs;

	for (i = 0; i < ti.max_devs; ++i) {
	struct exofs_trunc_attr *size_attr = &size_attrs[i];
	u64 obj_size;

	if (i < ti.first_group_dev)
	obj_size = ti.prev_group_obj_off;
	else if (i >= ti.nex_group_dev)
	obj_size = ti.next_group_obj_off;
	else if (i < ti.si.dev) /* dev within this group */
	obj_size = ti.si.obj_offset +
	ios->layout->stripe_unit - ti.si.unit_off;
	else if (i == ti.si.dev)
	obj_size = ti.si.obj_offset;
	else /* i > ti.dev */
	obj_size = ti.si.obj_offset - ti.si.unit_off;

	size_attr->newsize = cpu_to_be64(obj_size);
	size_attr->attr = g_attr_logical_length;
	size_attr->attr.val_ptr = &size_attr->newsize;

	ORE_DBGMSG("trunc(0x%llx) obj_offset=0x%llx dev=%d\n",
	_LLU(comps->comps->obj.id), _LLU(obj_size), i);
	ret = _truncate_mirrors(ios, i * ios->layout->mirrors_p1,
	&size_attr->attr);
	if (unlikely(ret))
	goto out;
	}
	ret = ore_io_execute(ios);

	out:
	kfree(size_attrs);
	ore_put_io_state(ios);
	return ret;
	}
	EXPORT_SYMBOL(ore_truncate);

	const struct osd_attr g_attr_logical_length = ATTR_DEF(
	OSD_APAGE_OBJECT_INFORMATION, OSD_ATTR_OI_LOGICAL_LENGTH, 8);
	EXPORT_SYMBOL(g_attr_logical_length);