1 files changed, 1057 insertions, 0 deletions

diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
new file mode 100644
index 00000000000..9cf208df1f2
--- /dev/null
+++ b/fs/nfs/objlayout/objio_osd.c
@@ -0,0 +1,1057 @@
+/*
+ *  pNFS Objects layout implementation over open-osd initiator library
+ *
+ *  Copyright (C) 2009 Panasas Inc. [year of first publication]
+ *  All rights reserved.
+ *
+ *  Benny Halevy <bhalevy@panasas.com>
+ *  Boaz Harrosh <bharrosh@panasas.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  See the file COPYING included with this distribution for more details.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions
+ *  are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. Neither the name of the Panasas company nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/module.h>
+#include <scsi/osd_initiator.h>
+
+#include "objlayout.h"
+
+#define NFSDBG_FACILITY         NFSDBG_PNFS_LD
+
+#define _LLU(x) ((unsigned long long)x)
+
+enum { BIO_MAX_PAGES_KMALLOC =
+		(PAGE_SIZE - sizeof(struct bio)) / sizeof(struct bio_vec),
+};
+
+struct objio_dev_ent {
+	struct nfs4_deviceid_node id_node;
+	struct osd_dev *od;
+};
+
+static void
+objio_free_deviceid_node(struct nfs4_deviceid_node *d)
+{
+	struct objio_dev_ent *de = container_of(d, struct objio_dev_ent, id_node);
+
+	dprintk("%s: free od=%p\n", __func__, de->od);
+	osduld_put_device(de->od);
+	kfree(de);
+}
+
+static struct objio_dev_ent *_dev_list_find(const struct nfs_server *nfss,
+	const struct nfs4_deviceid *d_id)
+{
+	struct nfs4_deviceid_node *d;
+	struct objio_dev_ent *de;
+
+	d = nfs4_find_get_deviceid(nfss->pnfs_curr_ld, nfss->nfs_client, d_id);
+	if (!d)
+		return NULL;
+
+	de = container_of(d, struct objio_dev_ent, id_node);
+	return de;
+}
+
+static struct objio_dev_ent *
+_dev_list_add(const struct nfs_server *nfss,
+	const struct nfs4_deviceid *d_id, struct osd_dev *od,
+	gfp_t gfp_flags)
+{
+	struct nfs4_deviceid_node *d;
+	struct objio_dev_ent *de = kzalloc(sizeof(*de), gfp_flags);
+	struct objio_dev_ent *n;
+
+	if (!de) {
+		dprintk("%s: -ENOMEM od=%p\n", __func__, od);
+		return NULL;
+	}
+
+	dprintk("%s: Adding od=%p\n", __func__, od);
+	nfs4_init_deviceid_node(&de->id_node,
+				nfss->pnfs_curr_ld,
+				nfss->nfs_client,
+				d_id);
+	de->od = od;
+
+	d = nfs4_insert_deviceid_node(&de->id_node);
+	n = container_of(d, struct objio_dev_ent, id_node);
+	if (n != de) {
+		dprintk("%s: Race with other n->od=%p\n", __func__, n->od);
+		objio_free_deviceid_node(&de->id_node);
+		de = n;
+	}
+
+	atomic_inc(&de->id_node.ref);
+	return de;
+}
+
+struct caps_buffers {
+	u8 caps_key[OSD_CRYPTO_KEYID_SIZE];
+	u8 creds[OSD_CAP_LEN];
+};
+
+struct objio_segment {
+	struct pnfs_layout_segment lseg;
+
+	struct pnfs_osd_object_cred *comps;
+
+	unsigned mirrors_p1;
+	unsigned stripe_unit;
+	unsigned group_width;	/* Data stripe_units without integrity comps */
+	u64 group_depth;
+	unsigned group_count;
+
+	unsigned max_io_size;
+
+	unsigned comps_index;
+	unsigned num_comps;
+	/* variable length */
+	struct objio_dev_ent *ods[];
+};
+
+static inline struct objio_segment *
+OBJIO_LSEG(struct pnfs_layout_segment *lseg)
+{
+	return container_of(lseg, struct objio_segment, lseg);
+}
+
+struct objio_state;
+typedef ssize_t (*objio_done_fn)(struct objio_state *ios);
+
+struct objio_state {
+	/* Generic layer */
+	struct objlayout_io_state ol_state;
+
+	struct objio_segment *layout;
+
+	struct kref kref;
+	objio_done_fn done;
+	void *private;
+
+	unsigned long length;
+	unsigned numdevs; /* Actually used devs in this IO */
+	/* A per-device variable array of size numdevs */
+	struct _objio_per_comp {
+		struct bio *bio;
+		struct osd_request *or;
+		unsigned long length;
+		u64 offset;
+		unsigned dev;
+	} per_dev[];
+};
+
+/* Send and wait for a get_device_info of devices in the layout,
+   then look them up with the osd_initiator library */
+static struct objio_dev_ent *_device_lookup(struct pnfs_layout_hdr *pnfslay,
+				struct objio_segment *objio_seg, unsigned comp,
+				gfp_t gfp_flags)
+{
+	struct pnfs_osd_deviceaddr *deviceaddr;
+	struct nfs4_deviceid *d_id;
+	struct objio_dev_ent *ode;
+	struct osd_dev *od;
+	struct osd_dev_info odi;
+	int err;
+
+	d_id = &objio_seg->comps[comp].oc_object_id.oid_device_id;
+
+	ode = _dev_list_find(NFS_SERVER(pnfslay->plh_inode), d_id);
+	if (ode)
+		return ode;
+
+	err = objlayout_get_deviceinfo(pnfslay, d_id, &deviceaddr, gfp_flags);
+	if (unlikely(err)) {
+		dprintk("%s: objlayout_get_deviceinfo dev(%llx:%llx) =>%d\n",
+			__func__, _DEVID_LO(d_id), _DEVID_HI(d_id), err);
+		return ERR_PTR(err);
+	}
+
+	odi.systemid_len = deviceaddr->oda_systemid.len;
+	if (odi.systemid_len > sizeof(odi.systemid)) {
+		err = -EINVAL;
+		goto out;
+	} else if (odi.systemid_len)
+		memcpy(odi.systemid, deviceaddr->oda_systemid.data,
+		       odi.systemid_len);
+	odi.osdname_len	 = deviceaddr->oda_osdname.len;
+	odi.osdname	 = (u8 *)deviceaddr->oda_osdname.data;
+
+	if (!odi.osdname_len && !odi.systemid_len) {
+		dprintk("%s: !odi.osdname_len && !odi.systemid_len\n",
+			__func__);
+		err = -ENODEV;
+		goto out;
+	}
+
+	od = osduld_info_lookup(&odi);
+	if (unlikely(IS_ERR(od))) {
+		err = PTR_ERR(od);
+		dprintk("%s: osduld_info_lookup => %d\n", __func__, err);
+		goto out;
+	}
+
+	ode = _dev_list_add(NFS_SERVER(pnfslay->plh_inode), d_id, od,
+			    gfp_flags);
+
+out:
+	dprintk("%s: return=%d\n", __func__, err);
+	objlayout_put_deviceinfo(deviceaddr);
+	return err ? ERR_PTR(err) : ode;
+}
+
+static int objio_devices_lookup(struct pnfs_layout_hdr *pnfslay,
+	struct objio_segment *objio_seg,
+	gfp_t gfp_flags)
+{
+	unsigned i;
+	int err;
+
+	/* lookup all devices */
+	for (i = 0; i < objio_seg->num_comps; i++) {
+		struct objio_dev_ent *ode;
+
+		ode = _device_lookup(pnfslay, objio_seg, i, gfp_flags);
+		if (unlikely(IS_ERR(ode))) {
+			err = PTR_ERR(ode);
+			goto out;
+		}
+		objio_seg->ods[i] = ode;
+	}
+	err = 0;
+
+out:
+	dprintk("%s: return=%d\n", __func__, err);
+	return err;
+}
+
+static int _verify_data_map(struct pnfs_osd_layout *layout)
+{
+	struct pnfs_osd_data_map *data_map = &layout->olo_map;
+	u64 stripe_length;
+	u32 group_width;
+
+/* FIXME: Only raid0 for now. if not go through MDS */
+	if (data_map->odm_raid_algorithm != PNFS_OSD_RAID_0) {
+		printk(KERN_ERR "Only RAID_0 for now\n");
+		return -ENOTSUPP;
+	}
+	if (0 != (data_map->odm_num_comps % (data_map->odm_mirror_cnt + 1))) {
+		printk(KERN_ERR "Data Map wrong, num_comps=%u mirrors=%u\n",
+			  data_map->odm_num_comps, data_map->odm_mirror_cnt);
+		return -EINVAL;
+	}
+
+	if (data_map->odm_group_width)
+		group_width = data_map->odm_group_width;
+	else
+		group_width = data_map->odm_num_comps /
+						(data_map->odm_mirror_cnt + 1);
+
+	stripe_length = (u64)data_map->odm_stripe_unit * group_width;
+	if (stripe_length >= (1ULL << 32)) {
+		printk(KERN_ERR "Total Stripe length(0x%llx)"
+			  " >= 32bit is not supported\n", _LLU(stripe_length));
+		return -ENOTSUPP;
+	}
+
+	if (0 != (data_map->odm_stripe_unit & ~PAGE_MASK)) {
+		printk(KERN_ERR "Stripe Unit(0x%llx)"
+			  " must be Multples of PAGE_SIZE(0x%lx)\n",
+			  _LLU(data_map->odm_stripe_unit), PAGE_SIZE);
+		return -ENOTSUPP;
+	}
+
+	return 0;
+}
+
+static void copy_single_comp(struct pnfs_osd_object_cred *cur_comp,
+			     struct pnfs_osd_object_cred *src_comp,
+			     struct caps_buffers *caps_p)
+{
+	WARN_ON(src_comp->oc_cap_key.cred_len > sizeof(caps_p->caps_key));
+	WARN_ON(src_comp->oc_cap.cred_len > sizeof(caps_p->creds));
+
+	*cur_comp = *src_comp;
+
+	memcpy(caps_p->caps_key, src_comp->oc_cap_key.cred,
+	       sizeof(caps_p->caps_key));
+	cur_comp->oc_cap_key.cred = caps_p->caps_key;
+
+	memcpy(caps_p->creds, src_comp->oc_cap.cred,
+	       sizeof(caps_p->creds));
+	cur_comp->oc_cap.cred = caps_p->creds;
+}
+
+int objio_alloc_lseg(struct pnfs_layout_segment **outp,
+	struct pnfs_layout_hdr *pnfslay,
+	struct pnfs_layout_range *range,
+	struct xdr_stream *xdr,
+	gfp_t gfp_flags)
+{
+	struct objio_segment *objio_seg;
+	struct pnfs_osd_xdr_decode_layout_iter iter;
+	struct pnfs_osd_layout layout;
+	struct pnfs_osd_object_cred *cur_comp, src_comp;
+	struct caps_buffers *caps_p;
+	int err;
+
+	err = pnfs_osd_xdr_decode_layout_map(&layout, &iter, xdr);
+	if (unlikely(err))
+		return err;
+
+	err = _verify_data_map(&layout);
+	if (unlikely(err))
+		return err;
+
+	objio_seg = kzalloc(sizeof(*objio_seg) +
+			    sizeof(objio_seg->ods[0]) * layout.olo_num_comps +
+			    sizeof(*objio_seg->comps) * layout.olo_num_comps +
+			    sizeof(struct caps_buffers) * layout.olo_num_comps,
+			    gfp_flags);
+	if (!objio_seg)
+		return -ENOMEM;
+
+	objio_seg->comps = (void *)(objio_seg->ods + layout.olo_num_comps);
+	cur_comp = objio_seg->comps;
+	caps_p = (void *)(cur_comp + layout.olo_num_comps);
+	while (pnfs_osd_xdr_decode_layout_comp(&src_comp, &iter, xdr, &err))
+		copy_single_comp(cur_comp++, &src_comp, caps_p++);
+	if (unlikely(err))
+		goto err;
+
+	objio_seg->num_comps = layout.olo_num_comps;
+	objio_seg->comps_index = layout.olo_comps_index;
+	err = objio_devices_lookup(pnfslay, objio_seg, gfp_flags);
+	if (err)
+		goto err;
+
+	objio_seg->mirrors_p1 = layout.olo_map.odm_mirror_cnt + 1;
+	objio_seg->stripe_unit = layout.olo_map.odm_stripe_unit;
+	if (layout.olo_map.odm_group_width) {
+		objio_seg->group_width = layout.olo_map.odm_group_width;
+		objio_seg->group_depth = layout.olo_map.odm_group_depth;
+		objio_seg->group_count = layout.olo_map.odm_num_comps /
+						objio_seg->mirrors_p1 /
+						objio_seg->group_width;
+	} else {
+		objio_seg->group_width = layout.olo_map.odm_num_comps /
+						objio_seg->mirrors_p1;
+		objio_seg->group_depth = -1;
+		objio_seg->group_count = 1;
+	}
+
+	/* Cache this calculation it will hit for every page */
+	objio_seg->max_io_size = (BIO_MAX_PAGES_KMALLOC * PAGE_SIZE -
+				  objio_seg->stripe_unit) *
+				 objio_seg->group_width;
+
+	*outp = &objio_seg->lseg;
+	return 0;
+
+err:
+	kfree(objio_seg);
+	dprintk("%s: Error: return %d\n", __func__, err);
+	*outp = NULL;
+	return err;
+}
+
+void objio_free_lseg(struct pnfs_layout_segment *lseg)
+{
+	int i;
+	struct objio_segment *objio_seg = OBJIO_LSEG(lseg);
+
+	for (i = 0; i < objio_seg->num_comps; i++) {
+		if (!objio_seg->ods[i])
+			break;
+		nfs4_put_deviceid_node(&objio_seg->ods[i]->id_node);
+	}
+	kfree(objio_seg);
+}
+
+int objio_alloc_io_state(struct pnfs_layout_segment *lseg,
+			 struct objlayout_io_state **outp,
+			 gfp_t gfp_flags)
+{
+	struct objio_segment *objio_seg = OBJIO_LSEG(lseg);
+	struct objio_state *ios;
+	const unsigned first_size = sizeof(*ios) +
+				objio_seg->num_comps * sizeof(ios->per_dev[0]);
+	const unsigned sec_size = objio_seg->num_comps *
+						sizeof(ios->ol_state.ioerrs[0]);
+
+	ios = kzalloc(first_size + sec_size, gfp_flags);
+	if (unlikely(!ios))
+		return -ENOMEM;
+
+	ios->layout = objio_seg;
+	ios->ol_state.ioerrs = ((void *)ios) + first_size;
+	ios->ol_state.num_comps = objio_seg->num_comps;
+
+	*outp = &ios->ol_state;
+	return 0;
+}
+
+void objio_free_io_state(struct objlayout_io_state *ol_state)
+{
+	struct objio_state *ios = container_of(ol_state, struct objio_state,
+					       ol_state);
+
+	kfree(ios);
+}
+
+enum pnfs_osd_errno osd_pri_2_pnfs_err(enum osd_err_priority oep)
+{
+	switch (oep) {
+	case OSD_ERR_PRI_NO_ERROR:
+		return (enum pnfs_osd_errno)0;
+
+	case OSD_ERR_PRI_CLEAR_PAGES:
+		BUG_ON(1);
+		return 0;
+
+	case OSD_ERR_PRI_RESOURCE:
+		return PNFS_OSD_ERR_RESOURCE;
+	case OSD_ERR_PRI_BAD_CRED:
+		return PNFS_OSD_ERR_BAD_CRED;
+	case OSD_ERR_PRI_NO_ACCESS:
+		return PNFS_OSD_ERR_NO_ACCESS;
+	case OSD_ERR_PRI_UNREACHABLE:
+		return PNFS_OSD_ERR_UNREACHABLE;
+	case OSD_ERR_PRI_NOT_FOUND:
+		return PNFS_OSD_ERR_NOT_FOUND;
+	case OSD_ERR_PRI_NO_SPACE:
+		return PNFS_OSD_ERR_NO_SPACE;
+	default:
+		WARN_ON(1);
+		/* fallthrough */
+	case OSD_ERR_PRI_EIO:
+		return PNFS_OSD_ERR_EIO;
+	}
+}
+
+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);
+	}
+}
+
+static int _io_check(struct objio_state *ios, bool is_write)
+{
+	enum osd_err_priority oep = OSD_ERR_PRI_NO_ERROR;
+	int lin_ret = 0;
+	int i;
+
+	for (i = 0; i <  ios->numdevs; i++) {
+		struct osd_sense_info osi;
+		struct osd_request *or = ios->per_dev[i].or;
+		unsigned dev;
+		int ret;
+
+		if (!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 */
+			BUG_ON(is_write);
+			_clear_bio(ios->per_dev[i].bio);
+			dprintk("%s: start read offset passed end of file "
+				"offset=0x%llx, length=0x%lx\n", __func__,
+				_LLU(ios->per_dev[i].offset),
+				ios->per_dev[i].length);
+
+			continue; /* we recovered */
+		}
+		dev = ios->per_dev[i].dev;
+		objlayout_io_set_result(&ios->ol_state, dev,
+					&ios->layout->comps[dev].oc_object_id,
+					osd_pri_2_pnfs_err(osi.osd_err_pri),
+					ios->per_dev[i].offset,
+					ios->per_dev[i].length,
+					is_write);
+
+		if (osi.osd_err_pri >= oep) {
+			oep = osi.osd_err_pri;
+			lin_ret = ret;
+		}
+	}
+
+	return lin_ret;
+}
+
+/*
+ * Common IO state helpers.
+ */
+static void _io_free(struct objio_state *ios)
+{
+	unsigned i;
+
+	for (i = 0; i < ios->numdevs; i++) {
+		struct _objio_per_comp *per_dev = &ios->per_dev[i];
+
+		if (per_dev->or) {
+			osd_end_request(per_dev->or);
+			per_dev->or = NULL;
+		}
+
+		if (per_dev->bio) {
+			bio_put(per_dev->bio);
+			per_dev->bio = NULL;
+		}
+	}
+}
+
+struct osd_dev *_io_od(struct objio_state *ios, unsigned dev)
+{
+	unsigned min_dev = ios->layout->comps_index;
+	unsigned max_dev = min_dev + ios->layout->num_comps;
+
+	BUG_ON(dev < min_dev || max_dev <= dev);
+	return ios->layout->ods[dev - min_dev]->od;
+}
+
+struct _striping_info {
+	u64 obj_offset;
+	u64 group_length;
+	unsigned dev;
+	unsigned unit_off;
+};
+
+static void _calc_stripe_info(struct objio_state *ios, u64 file_offset,
+			      struct _striping_info *si)
+{
+	u32	stripe_unit = ios->layout->stripe_unit;
+	u32	group_width = ios->layout->group_width;
+	u64	group_depth = ios->layout->group_depth;
+	u32	U = stripe_unit * group_width;
+
+	u64	T = U * group_depth;
+	u64	S = T * ios->layout->group_count;
+	u64	M = div64_u64(file_offset, S);
+
+	/*
+	G = (L - (M * S)) / T
+	H = (L - (M * S)) % T
+	*/
+	u64	LmodU = file_offset - M * S;
+	u32	G = div64_u64(LmodU, T);
+	u64	H = LmodU - G * T;
+
+	u32	N = div_u64(H, U);
+
+	div_u64_rem(file_offset, stripe_unit, &si->unit_off);
+	si->obj_offset = si->unit_off + (N * stripe_unit) +
+				  (M * group_depth * stripe_unit);
+
+	/* "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 *= ios->layout->mirrors_p1;
+
+	si->group_length = T - H;
+}
+
+static int _add_stripe_unit(struct objio_state *ios,  unsigned *cur_pg,
+		unsigned pgbase, struct _objio_per_comp *per_dev, int cur_len,
+		gfp_t gfp_flags)
+{
+	unsigned pg = *cur_pg;
+	struct request_queue *q =
+			osd_request_queue(_io_od(ios, per_dev->dev));
+
+	per_dev->length += cur_len;
+
+	if (per_dev->bio == NULL) {
+		unsigned stripes = ios->layout->num_comps /
+						     ios->layout->mirrors_p1;
+		unsigned pages_in_stripe = stripes *
+				      (ios->layout->stripe_unit / PAGE_SIZE);
+		unsigned bio_size = (ios->ol_state.nr_pages + pages_in_stripe) /
+				    stripes;
+
+		if (BIO_MAX_PAGES_KMALLOC < bio_size)
+			bio_size = BIO_MAX_PAGES_KMALLOC;
+
+		per_dev->bio = bio_kmalloc(gfp_flags, bio_size);
+		if (unlikely(!per_dev->bio)) {
+			dprintk("Faild 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->ol_state.nr_pages <= pg);
+		cur_len -= pglen;
+
+		added_len = bio_add_pc_page(q, per_dev->bio,
+					ios->ol_state.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 objio_state *ios, u64 length,
+			      struct _striping_info *si, unsigned *last_pg,
+			      gfp_t gfp_flags)
+{
+	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 = *last_pg;
+	int ret = 0;
+
+	while (length) {
+		struct _objio_per_comp *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->ol_state.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, gfp_flags);
+		if (unlikely(ret))
+			goto out;
+
+		dev += mirrors_p1;
+		dev = (dev % devs_in_group) + first_dev;
+
+		length -= cur_len;
+		ios->length += cur_len;
+	}
+out:
+	ios->numdevs = max_comp + mirrors_p1;
+	*last_pg = cur_pg;
+	return ret;
+}
+
+static int _io_rw_pagelist(struct objio_state *ios, gfp_t gfp_flags)
+{
+	u64 length = ios->ol_state.count;
+	u64 offset = ios->ol_state.offset;
+	struct _striping_info si;
+	unsigned last_pg = 0;
+	int ret = 0;
+
+	while (length) {
+		_calc_stripe_info(ios, offset, &si);
+
+		if (length < si.group_length)
+			si.group_length = length;
+
+		ret = _prepare_one_group(ios, si.group_length, &si, &last_pg, gfp_flags);
+		if (unlikely(ret))
+			goto out;
+
+		offset += si.group_length;
+		length -= si.group_length;
+	}
+
+out:
+	if (!ios->length)
+		return ret;
+
+	return 0;
+}
+
+static ssize_t _sync_done(struct objio_state *ios)
+{
+	struct completion *waiting = ios->private;
+
+	complete(waiting);
+	return 0;
+}
+
+static void _last_io(struct kref *kref)
+{
+	struct objio_state *ios = container_of(kref, struct objio_state, kref);
+
+	ios->done(ios);
+}
+
+static void _done_io(struct osd_request *or, void *p)
+{
+	struct objio_state *ios = p;
+
+	kref_put(&ios->kref, _last_io);
+}
+
+static ssize_t _io_exec(struct objio_state *ios)
+{
+	DECLARE_COMPLETION_ONSTACK(wait);
+	ssize_t status = 0; /* sync status */
+	unsigned i;
+	objio_done_fn saved_done_fn = ios->done;
+	bool sync = ios->ol_state.sync;
+
+	if (sync) {
+		ios->done = _sync_done;
+		ios->private = &wait;
+	}
+
+	kref_init(&ios->kref);
+
+	for (i = 0; i < ios->numdevs; i++) {
+		struct osd_request *or = ios->per_dev[i].or;
+
+		if (!or)
+			continue;
+
+		kref_get(&ios->kref);
+		osd_execute_request_async(or, _done_io, ios);
+	}
+
+	kref_put(&ios->kref, _last_io);
+
+	if (sync) {
+		wait_for_completion(&wait);
+		status = saved_done_fn(ios);
+	}
+
+	return status;
+}
+
+/*
+ * read
+ */
+static ssize_t _read_done(struct objio_state *ios)
+{
+	ssize_t status;
+	int ret = _io_check(ios, false);
+
+	_io_free(ios);
+
+	if (likely(!ret))
+		status = ios->length;
+	else
+		status = ret;
+
+	objlayout_read_done(&ios->ol_state, status, ios->ol_state.sync);
+	return status;
+}
+
+static int _read_mirrors(struct objio_state *ios, unsigned cur_comp)
+{
+	struct osd_request *or = NULL;
+	struct _objio_per_comp *per_dev = &ios->per_dev[cur_comp];
+	unsigned dev = per_dev->dev;
+	struct pnfs_osd_object_cred *cred =
+			&ios->layout->comps[dev];
+	struct osd_obj_id obj = {
+		.partition = cred->oc_object_id.oid_partition_id,
+		.id = cred->oc_object_id.oid_object_id,
+	};
+	int ret;
+
+	or = osd_start_request(_io_od(ios, dev), GFP_KERNEL);
+	if (unlikely(!or)) {
+		ret = -ENOMEM;
+		goto err;
+	}
+	per_dev->or = or;
+
+	osd_req_read(or, &obj, per_dev->offset, per_dev->bio, per_dev->length);
+
+	ret = osd_finalize_request(or, 0, cred->oc_cap.cred, NULL);
+	if (ret) {
+		dprintk("%s: Faild to osd_finalize_request() => %d\n",
+			__func__, ret);
+		goto err;
+	}
+
+	dprintk("%s:[%d] dev=%d obj=0x%llx start=0x%llx length=0x%lx\n",
+		__func__, cur_comp, dev, obj.id, _LLU(per_dev->offset),
+		per_dev->length);
+
+err:
+	return ret;
+}
+
+static ssize_t _read_exec(struct objio_state *ios)
+{
+	unsigned i;
+	int ret;
+
+	for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
+		if (!ios->per_dev[i].length)
+			continue;
+		ret = _read_mirrors(ios, i);
+		if (unlikely(ret))
+			goto err;
+	}
+
+	ios->done = _read_done;
+	return _io_exec(ios); /* In sync mode exec returns the io status */
+
+err:
+	_io_free(ios);
+	return ret;
+}
+
+ssize_t objio_read_pagelist(struct objlayout_io_state *ol_state)
+{
+	struct objio_state *ios = container_of(ol_state, struct objio_state,
+					       ol_state);
+	int ret;
+
+	ret = _io_rw_pagelist(ios, GFP_KERNEL);
+	if (unlikely(ret))
+		return ret;
+
+	return _read_exec(ios);
+}
+
+/*
+ * write
+ */
+static ssize_t _write_done(struct objio_state *ios)
+{
+	ssize_t status;
+	int ret = _io_check(ios, true);
+
+	_io_free(ios);
+
+	if (likely(!ret)) {
+		/* FIXME: should be based on the OSD's persistence model
+		 * See OSD2r05 Section 4.13 Data persistence model */
+		ios->ol_state.committed = NFS_FILE_SYNC;
+		status = ios->length;
+	} else {
+		status = ret;
+	}
+
+	objlayout_write_done(&ios->ol_state, status, ios->ol_state.sync);
+	return status;
+}
+
+static int _write_mirrors(struct objio_state *ios, unsigned cur_comp)
+{
+	struct _objio_per_comp *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;
+
+	for (; cur_comp < last_comp; ++cur_comp, ++dev) {
+		struct osd_request *or = NULL;
+		struct pnfs_osd_object_cred *cred =
+					&ios->layout->comps[dev];
+		struct osd_obj_id obj = {
+			.partition = cred->oc_object_id.oid_partition_id,
+			.id = cred->oc_object_id.oid_object_id,
+		};
+		struct _objio_per_comp *per_dev = &ios->per_dev[cur_comp];
+		struct bio *bio;
+
+		or = osd_start_request(_io_od(ios, dev), GFP_NOFS);
+		if (unlikely(!or)) {
+			ret = -ENOMEM;
+			goto err;
+		}
+		per_dev->or = or;
+
+		if (per_dev != master_dev) {
+			bio = bio_kmalloc(GFP_NOFS,
+					  master_dev->bio->bi_max_vecs);
+			if (unlikely(!bio)) {
+				dprintk("Faild to allocate BIO size=%u\n",
+					master_dev->bio->bi_max_vecs);
+				ret = -ENOMEM;
+				goto err;
+			}
+
+			__bio_clone(bio, master_dev->bio);
+			bio->bi_bdev = NULL;
+			bio->bi_next = NULL;
+			per_dev->bio = bio;
+			per_dev->dev = dev;
+			per_dev->length = master_dev->length;
+			per_dev->offset =  master_dev->offset;
+		} else {
+			bio = master_dev->bio;
+			bio->bi_rw |= REQ_WRITE;
+		}
+
+		osd_req_write(or, &obj, per_dev->offset, bio, per_dev->length);
+
+		ret = osd_finalize_request(or, 0, cred->oc_cap.cred, NULL);
+		if (ret) {
+			dprintk("%s: Faild to osd_finalize_request() => %d\n",
+				__func__, ret);
+			goto err;
+		}
+
+		dprintk("%s:[%d] dev=%d obj=0x%llx start=0x%llx length=0x%lx\n",
+			__func__, cur_comp, dev, obj.id, _LLU(per_dev->offset),
+			per_dev->length);
+	}
+
+err:
+	return ret;
+}
+
+static ssize_t _write_exec(struct objio_state *ios)
+{
+	unsigned i;
+	int ret;
+
+	for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
+		if (!ios->per_dev[i].length)
+			continue;
+		ret = _write_mirrors(ios, i);
+		if (unlikely(ret))
+			goto err;
+	}
+
+	ios->done = _write_done;
+	return _io_exec(ios); /* In sync mode exec returns the io->status */
+
+err:
+	_io_free(ios);
+	return ret;
+}
+
+ssize_t objio_write_pagelist(struct objlayout_io_state *ol_state, bool stable)
+{
+	struct objio_state *ios = container_of(ol_state, struct objio_state,
+					       ol_state);
+	int ret;
+
+	/* TODO: ios->stable = stable; */
+	ret = _io_rw_pagelist(ios, GFP_NOFS);
+	if (unlikely(ret))
+		return ret;
+
+	return _write_exec(ios);
+}
+
+static bool objio_pg_test(struct nfs_pageio_descriptor *pgio,
+			  struct nfs_page *prev, struct nfs_page *req)
+{
+	if (!pnfs_generic_pg_test(pgio, prev, req))
+		return false;
+
+	return pgio->pg_count + req->wb_bytes <=
+			OBJIO_LSEG(pgio->pg_lseg)->max_io_size;
+}
+
+static struct pnfs_layoutdriver_type objlayout_type = {
+	.id = LAYOUT_OSD2_OBJECTS,
+	.name = "LAYOUT_OSD2_OBJECTS",
+	.flags                   = PNFS_LAYOUTRET_ON_SETATTR,
+
+	.alloc_layout_hdr        = objlayout_alloc_layout_hdr,
+	.free_layout_hdr         = objlayout_free_layout_hdr,
+
+	.alloc_lseg              = objlayout_alloc_lseg,
+	.free_lseg               = objlayout_free_lseg,
+
+	.read_pagelist           = objlayout_read_pagelist,
+	.write_pagelist          = objlayout_write_pagelist,
+	.pg_test                 = objio_pg_test,
+
+	.free_deviceid_node	 = objio_free_deviceid_node,
+
+	.encode_layoutcommit	 = objlayout_encode_layoutcommit,
+	.encode_layoutreturn     = objlayout_encode_layoutreturn,
+};
+
+MODULE_DESCRIPTION("pNFS Layout Driver for OSD2 objects");
+MODULE_AUTHOR("Benny Halevy <bhalevy@panasas.com>");
+MODULE_LICENSE("GPL");
+
+static int __init
+objlayout_init(void)
+{
+	int ret = pnfs_register_layoutdriver(&objlayout_type);
+
+	if (ret)
+		printk(KERN_INFO
+			"%s: Registering OSD pNFS Layout Driver failed: error=%d\n",
+			__func__, ret);
+	else
+		printk(KERN_INFO "%s: Registered OSD pNFS Layout Driver\n",
+			__func__);
+	return ret;
+}
+
+static void __exit
+objlayout_exit(void)
+{
+	pnfs_unregister_layoutdriver(&objlayout_type);
+	printk(KERN_INFO "%s: Unregistered OSD pNFS Layout Driver\n",
+	       __func__);
+}
+
+module_init(objlayout_init);
+module_exit(objlayout_exit);