exofs: Rename raid engine from exofs/ios.c => ore

ORE stands for "Objects Raid Engine"

This patch is a mechanical rename of everything that was in ios.c
and its API declaration to an ore.c and an osd_ore.h header. The ore
engine will later be used by the pnfs objects layout driver.

* File ios.c => ore.c

* Declaration of types and API are moved from exofs.h to a new
  osd_ore.h

* All used types are prefixed by ore_ from their exofs_ name.

* Shift includes from exofs.h to osd_ore.h so osd_ore.h is
  independent, include it from exofs.h.

Other than a pure rename there are no other changes. Next patch
will move the ore into it's own module and will export the API
to be used by exofs and later the layout driver

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

1 files changed, 820 insertions, 0 deletions

diff --git a/fs/exofs/ore.c b/fs/exofs/ore.c
new file mode 100644
index 000000000000..3a000084cd21
--- /dev/null
+++ b/fs/exofs/ore.c
@@ -0,0 +1,820 @@
+/*
+ * 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 */
+
+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;
+}
+
+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);
+}
+
+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);
+	}
+}
+
+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;
+}
+
+/*
+ * 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;
+}
+
+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;
+}
+
+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;
+}
+
+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;
+}
+
+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;
+}
+
+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;
+}
+
+const struct osd_attr g_attr_logical_length = ATTR_DEF(
+	OSD_APAGE_OBJECT_INFORMATION, OSD_ATTR_OI_LOGICAL_LENGTH, 8);