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-rw-r--r--fs/exofs/ore.c835
1 files changed, 835 insertions, 0 deletions
diff --git a/fs/exofs/ore.c b/fs/exofs/ore.c
new file mode 100644
index 000000000000..25305af88198
--- /dev/null
+++ b/fs/exofs/ore.c
@@ -0,0 +1,835 @@
+/*
+ * 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);