Moved, renamed, and deleted files

The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.

1 files changed, 2633 insertions, 0 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
new file mode 100644
index 00000000..013c7a54
--- /dev/null
+++ b/drivers/block/rbd.c
@@ -0,0 +1,2633 @@
+/*
+   rbd.c -- Export ceph rados objects as a Linux block device
+
+
+   based on drivers/block/osdblk.c:
+
+   Copyright 2009 Red Hat, Inc.
+
+   This program 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.
+
+   This program 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 this program; see the file COPYING.  If not, write to
+   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+
+
+   For usage instructions, please refer to:
+
+                 Documentation/ABI/testing/sysfs-bus-rbd
+
+ */
+
+#include <linux/ceph/libceph.h>
+#include <linux/ceph/osd_client.h>
+#include <linux/ceph/mon_client.h>
+#include <linux/ceph/decode.h>
+#include <linux/parser.h>
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+
+#include "rbd_types.h"
+
+/*
+ * The basic unit of block I/O is a sector.  It is interpreted in a
+ * number of contexts in Linux (blk, bio, genhd), but the default is
+ * universally 512 bytes.  These symbols are just slightly more
+ * meaningful than the bare numbers they represent.
+ */
+#define	SECTOR_SHIFT	9
+#define	SECTOR_SIZE	(1ULL << SECTOR_SHIFT)
+
+#define RBD_DRV_NAME "rbd"
+#define RBD_DRV_NAME_LONG "rbd (rados block device)"
+
+#define RBD_MINORS_PER_MAJOR	256		/* max minors per blkdev */
+
+#define RBD_MAX_MD_NAME_LEN	(RBD_MAX_OBJ_NAME_LEN + sizeof(RBD_SUFFIX))
+#define RBD_MAX_POOL_NAME_LEN	64
+#define RBD_MAX_SNAP_NAME_LEN	32
+#define RBD_MAX_OPT_LEN		1024
+
+#define RBD_SNAP_HEAD_NAME	"-"
+
+/*
+ * An RBD device name will be "rbd#", where the "rbd" comes from
+ * RBD_DRV_NAME above, and # is a unique integer identifier.
+ * MAX_INT_FORMAT_WIDTH is used in ensuring DEV_NAME_LEN is big
+ * enough to hold all possible device names.
+ */
+#define DEV_NAME_LEN		32
+#define MAX_INT_FORMAT_WIDTH	((5 * sizeof (int)) / 2 + 1)
+
+#define RBD_NOTIFY_TIMEOUT_DEFAULT 10
+
+/*
+ * block device image metadata (in-memory version)
+ */
+struct rbd_image_header {
+	u64 image_size;
+	char block_name[32];
+	__u8 obj_order;
+	__u8 crypt_type;
+	__u8 comp_type;
+	struct ceph_snap_context *snapc;
+	size_t snap_names_len;
+	u64 snap_seq;
+	u32 total_snaps;
+
+	char *snap_names;
+	u64 *snap_sizes;
+
+	u64 obj_version;
+};
+
+struct rbd_options {
+	int	notify_timeout;
+};
+
+/*
+ * an instance of the client.  multiple devices may share an rbd client.
+ */
+struct rbd_client {
+	struct ceph_client	*client;
+	struct rbd_options	*rbd_opts;
+	struct kref		kref;
+	struct list_head	node;
+};
+
+/*
+ * a request completion status
+ */
+struct rbd_req_status {
+	int done;
+	int rc;
+	u64 bytes;
+};
+
+/*
+ * a collection of requests
+ */
+struct rbd_req_coll {
+	int			total;
+	int			num_done;
+	struct kref		kref;
+	struct rbd_req_status	status[0];
+};
+
+/*
+ * a single io request
+ */
+struct rbd_request {
+	struct request		*rq;		/* blk layer request */
+	struct bio		*bio;		/* cloned bio */
+	struct page		**pages;	/* list of used pages */
+	u64			len;
+	int			coll_index;
+	struct rbd_req_coll	*coll;
+};
+
+struct rbd_snap {
+	struct	device		dev;
+	const char		*name;
+	size_t			size;
+	struct list_head	node;
+	u64			id;
+};
+
+/*
+ * a single device
+ */
+struct rbd_device {
+	int			id;		/* blkdev unique id */
+
+	int			major;		/* blkdev assigned major */
+	struct gendisk		*disk;		/* blkdev's gendisk and rq */
+	struct request_queue	*q;
+
+	struct rbd_client	*rbd_client;
+
+	char			name[DEV_NAME_LEN]; /* blkdev name, e.g. rbd3 */
+
+	spinlock_t		lock;		/* queue lock */
+
+	struct rbd_image_header	header;
+	char			obj[RBD_MAX_OBJ_NAME_LEN]; /* rbd image name */
+	int			obj_len;
+	char			obj_md_name[RBD_MAX_MD_NAME_LEN]; /* hdr nm. */
+	char			pool_name[RBD_MAX_POOL_NAME_LEN];
+	int			poolid;
+
+	struct ceph_osd_event   *watch_event;
+	struct ceph_osd_request *watch_request;
+
+	/* protects updating the header */
+	struct rw_semaphore     header_rwsem;
+	char                    snap_name[RBD_MAX_SNAP_NAME_LEN];
+	u32 cur_snap;	/* index+1 of current snapshot within snap context
+			   0 - for the head */
+	int read_only;
+
+	struct list_head	node;
+
+	/* list of snapshots */
+	struct list_head	snaps;
+
+	/* sysfs related */
+	struct device		dev;
+};
+
+static DEFINE_MUTEX(ctl_mutex);	  /* Serialize open/close/setup/teardown */
+
+static LIST_HEAD(rbd_dev_list);    /* devices */
+static DEFINE_SPINLOCK(rbd_dev_list_lock);
+
+static LIST_HEAD(rbd_client_list);		/* clients */
+static DEFINE_SPINLOCK(rbd_client_list_lock);
+
+static int __rbd_init_snaps_header(struct rbd_device *rbd_dev);
+static void rbd_dev_release(struct device *dev);
+static ssize_t rbd_snap_add(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf,
+			    size_t count);
+static void __rbd_remove_snap_dev(struct rbd_device *rbd_dev,
+				  struct rbd_snap *snap);
+
+static ssize_t rbd_add(struct bus_type *bus, const char *buf,
+		       size_t count);
+static ssize_t rbd_remove(struct bus_type *bus, const char *buf,
+			  size_t count);
+
+static struct bus_attribute rbd_bus_attrs[] = {
+	__ATTR(add, S_IWUSR, NULL, rbd_add),
+	__ATTR(remove, S_IWUSR, NULL, rbd_remove),
+	__ATTR_NULL
+};
+
+static struct bus_type rbd_bus_type = {
+	.name		= "rbd",
+	.bus_attrs	= rbd_bus_attrs,
+};
+
+static void rbd_root_dev_release(struct device *dev)
+{
+}
+
+static struct device rbd_root_dev = {
+	.init_name =    "rbd",
+	.release =      rbd_root_dev_release,
+};
+
+
+static struct device *rbd_get_dev(struct rbd_device *rbd_dev)
+{
+	return get_device(&rbd_dev->dev);
+}
+
+static void rbd_put_dev(struct rbd_device *rbd_dev)
+{
+	put_device(&rbd_dev->dev);
+}
+
+static int __rbd_update_snaps(struct rbd_device *rbd_dev);
+
+static int rbd_open(struct block_device *bdev, fmode_t mode)
+{
+	struct rbd_device *rbd_dev = bdev->bd_disk->private_data;
+
+	rbd_get_dev(rbd_dev);
+
+	set_device_ro(bdev, rbd_dev->read_only);
+
+	if ((mode & FMODE_WRITE) && rbd_dev->read_only)
+		return -EROFS;
+
+	return 0;
+}
+
+static int rbd_release(struct gendisk *disk, fmode_t mode)
+{
+	struct rbd_device *rbd_dev = disk->private_data;
+
+	rbd_put_dev(rbd_dev);
+
+	return 0;
+}
+
+static const struct block_device_operations rbd_bd_ops = {
+	.owner			= THIS_MODULE,
+	.open			= rbd_open,
+	.release		= rbd_release,
+};
+
+/*
+ * Initialize an rbd client instance.
+ * We own *opt.
+ */
+static struct rbd_client *rbd_client_create(struct ceph_options *opt,
+					    struct rbd_options *rbd_opts)
+{
+	struct rbd_client *rbdc;
+	int ret = -ENOMEM;
+
+	dout("rbd_client_create\n");
+	rbdc = kmalloc(sizeof(struct rbd_client), GFP_KERNEL);
+	if (!rbdc)
+		goto out_opt;
+
+	kref_init(&rbdc->kref);
+	INIT_LIST_HEAD(&rbdc->node);
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+
+	rbdc->client = ceph_create_client(opt, rbdc, 0, 0);
+	if (IS_ERR(rbdc->client))
+		goto out_mutex;
+	opt = NULL; /* Now rbdc->client is responsible for opt */
+
+	ret = ceph_open_session(rbdc->client);
+	if (ret < 0)
+		goto out_err;
+
+	rbdc->rbd_opts = rbd_opts;
+
+	spin_lock(&rbd_client_list_lock);
+	list_add_tail(&rbdc->node, &rbd_client_list);
+	spin_unlock(&rbd_client_list_lock);
+
+	mutex_unlock(&ctl_mutex);
+
+	dout("rbd_client_create created %p\n", rbdc);
+	return rbdc;
+
+out_err:
+	ceph_destroy_client(rbdc->client);
+out_mutex:
+	mutex_unlock(&ctl_mutex);
+	kfree(rbdc);
+out_opt:
+	if (opt)
+		ceph_destroy_options(opt);
+	return ERR_PTR(ret);
+}
+
+/*
+ * Find a ceph client with specific addr and configuration.
+ */
+static struct rbd_client *__rbd_client_find(struct ceph_options *opt)
+{
+	struct rbd_client *client_node;
+
+	if (opt->flags & CEPH_OPT_NOSHARE)
+		return NULL;
+
+	list_for_each_entry(client_node, &rbd_client_list, node)
+		if (ceph_compare_options(opt, client_node->client) == 0)
+			return client_node;
+	return NULL;
+}
+
+/*
+ * mount options
+ */
+enum {
+	Opt_notify_timeout,
+	Opt_last_int,
+	/* int args above */
+	Opt_last_string,
+	/* string args above */
+};
+
+static match_table_t rbdopt_tokens = {
+	{Opt_notify_timeout, "notify_timeout=%d"},
+	/* int args above */
+	/* string args above */
+	{-1, NULL}
+};
+
+static int parse_rbd_opts_token(char *c, void *private)
+{
+	struct rbd_options *rbdopt = private;
+	substring_t argstr[MAX_OPT_ARGS];
+	int token, intval, ret;
+
+	token = match_token(c, rbdopt_tokens, argstr);
+	if (token < 0)
+		return -EINVAL;
+
+	if (token < Opt_last_int) {
+		ret = match_int(&argstr[0], &intval);
+		if (ret < 0) {
+			pr_err("bad mount option arg (not int) "
+			       "at '%s'\n", c);
+			return ret;
+		}
+		dout("got int token %d val %d\n", token, intval);
+	} else if (token > Opt_last_int && token < Opt_last_string) {
+		dout("got string token %d val %s\n", token,
+		     argstr[0].from);
+	} else {
+		dout("got token %d\n", token);
+	}
+
+	switch (token) {
+	case Opt_notify_timeout:
+		rbdopt->notify_timeout = intval;
+		break;
+	default:
+		BUG_ON(token);
+	}
+	return 0;
+}
+
+/*
+ * Get a ceph client with specific addr and configuration, if one does
+ * not exist create it.
+ */
+static struct rbd_client *rbd_get_client(const char *mon_addr,
+					 size_t mon_addr_len,
+					 char *options)
+{
+	struct rbd_client *rbdc;
+	struct ceph_options *opt;
+	struct rbd_options *rbd_opts;
+
+	rbd_opts = kzalloc(sizeof(*rbd_opts), GFP_KERNEL);
+	if (!rbd_opts)
+		return ERR_PTR(-ENOMEM);
+
+	rbd_opts->notify_timeout = RBD_NOTIFY_TIMEOUT_DEFAULT;
+
+	opt = ceph_parse_options(options, mon_addr,
+				mon_addr + mon_addr_len,
+				parse_rbd_opts_token, rbd_opts);
+	if (IS_ERR(opt)) {
+		kfree(rbd_opts);
+		return ERR_CAST(opt);
+	}
+
+	spin_lock(&rbd_client_list_lock);
+	rbdc = __rbd_client_find(opt);
+	if (rbdc) {
+		/* using an existing client */
+		kref_get(&rbdc->kref);
+		spin_unlock(&rbd_client_list_lock);
+
+		ceph_destroy_options(opt);
+		kfree(rbd_opts);
+
+		return rbdc;
+	}
+	spin_unlock(&rbd_client_list_lock);
+
+	rbdc = rbd_client_create(opt, rbd_opts);
+
+	if (IS_ERR(rbdc))
+		kfree(rbd_opts);
+
+	return rbdc;
+}
+
+/*
+ * Destroy ceph client
+ *
+ * Caller must hold rbd_client_list_lock.
+ */
+static void rbd_client_release(struct kref *kref)
+{
+	struct rbd_client *rbdc = container_of(kref, struct rbd_client, kref);
+
+	dout("rbd_release_client %p\n", rbdc);
+	list_del(&rbdc->node);
+
+	ceph_destroy_client(rbdc->client);
+	kfree(rbdc->rbd_opts);
+	kfree(rbdc);
+}
+
+/*
+ * Drop reference to ceph client node. If it's not referenced anymore, release
+ * it.
+ */
+static void rbd_put_client(struct rbd_device *rbd_dev)
+{
+	spin_lock(&rbd_client_list_lock);
+	kref_put(&rbd_dev->rbd_client->kref, rbd_client_release);
+	spin_unlock(&rbd_client_list_lock);
+	rbd_dev->rbd_client = NULL;
+}
+
+/*
+ * Destroy requests collection
+ */
+static void rbd_coll_release(struct kref *kref)
+{
+	struct rbd_req_coll *coll =
+		container_of(kref, struct rbd_req_coll, kref);
+
+	dout("rbd_coll_release %p\n", coll);
+	kfree(coll);
+}
+
+/*
+ * Create a new header structure, translate header format from the on-disk
+ * header.
+ */
+static int rbd_header_from_disk(struct rbd_image_header *header,
+				 struct rbd_image_header_ondisk *ondisk,
+				 int allocated_snaps,
+				 gfp_t gfp_flags)
+{
+	int i;
+	u32 snap_count;
+
+	if (memcmp(ondisk, RBD_HEADER_TEXT, sizeof(RBD_HEADER_TEXT)))
+		return -ENXIO;
+
+	snap_count = le32_to_cpu(ondisk->snap_count);
+	header->snapc = kmalloc(sizeof(struct ceph_snap_context) +
+				snap_count * sizeof (*ondisk),
+				gfp_flags);
+	if (!header->snapc)
+		return -ENOMEM;
+
+	header->snap_names_len = le64_to_cpu(ondisk->snap_names_len);
+	if (snap_count) {
+		header->snap_names = kmalloc(header->snap_names_len,
+					     GFP_KERNEL);
+		if (!header->snap_names)
+			goto err_snapc;
+		header->snap_sizes = kmalloc(snap_count * sizeof(u64),
+					     GFP_KERNEL);
+		if (!header->snap_sizes)
+			goto err_names;
+	} else {
+		header->snap_names = NULL;
+		header->snap_sizes = NULL;
+	}
+	memcpy(header->block_name, ondisk->block_name,
+	       sizeof(ondisk->block_name));
+
+	header->image_size = le64_to_cpu(ondisk->image_size);
+	header->obj_order = ondisk->options.order;
+	header->crypt_type = ondisk->options.crypt_type;
+	header->comp_type = ondisk->options.comp_type;
+
+	atomic_set(&header->snapc->nref, 1);
+	header->snap_seq = le64_to_cpu(ondisk->snap_seq);
+	header->snapc->num_snaps = snap_count;
+	header->total_snaps = snap_count;
+
+	if (snap_count && allocated_snaps == snap_count) {
+		for (i = 0; i < snap_count; i++) {
+			header->snapc->snaps[i] =
+				le64_to_cpu(ondisk->snaps[i].id);
+			header->snap_sizes[i] =
+				le64_to_cpu(ondisk->snaps[i].image_size);
+		}
+
+		/* copy snapshot names */
+		memcpy(header->snap_names, &ondisk->snaps[i],
+			header->snap_names_len);
+	}
+
+	return 0;
+
+err_names:
+	kfree(header->snap_names);
+err_snapc:
+	kfree(header->snapc);
+	return -ENOMEM;
+}
+
+static int snap_index(struct rbd_image_header *header, int snap_num)
+{
+	return header->total_snaps - snap_num;
+}
+
+static u64 cur_snap_id(struct rbd_device *rbd_dev)
+{
+	struct rbd_image_header *header = &rbd_dev->header;
+
+	if (!rbd_dev->cur_snap)
+		return 0;
+
+	return header->snapc->snaps[snap_index(header, rbd_dev->cur_snap)];
+}
+
+static int snap_by_name(struct rbd_image_header *header, const char *snap_name,
+			u64 *seq, u64 *size)
+{
+	int i;
+	char *p = header->snap_names;
+
+	for (i = 0; i < header->total_snaps; i++) {
+		if (!strcmp(snap_name, p)) {
+
+			/* Found it.  Pass back its id and/or size */
+
+			if (seq)
+				*seq = header->snapc->snaps[i];
+			if (size)
+				*size = header->snap_sizes[i];
+			return i;
+		}
+		p += strlen(p) + 1;	/* Skip ahead to the next name */
+	}
+	return -ENOENT;
+}
+
+static int rbd_header_set_snap(struct rbd_device *dev, u64 *size)
+{
+	struct rbd_image_header *header = &dev->header;
+	struct ceph_snap_context *snapc = header->snapc;
+	int ret = -ENOENT;
+
+	BUILD_BUG_ON(sizeof (dev->snap_name) < sizeof (RBD_SNAP_HEAD_NAME));
+
+	down_write(&dev->header_rwsem);
+
+	if (!memcmp(dev->snap_name, RBD_SNAP_HEAD_NAME,
+		    sizeof (RBD_SNAP_HEAD_NAME))) {
+		if (header->total_snaps)
+			snapc->seq = header->snap_seq;
+		else
+			snapc->seq = 0;
+		dev->cur_snap = 0;
+		dev->read_only = 0;
+		if (size)
+			*size = header->image_size;
+	} else {
+		ret = snap_by_name(header, dev->snap_name, &snapc->seq, size);
+		if (ret < 0)
+			goto done;
+
+		dev->cur_snap = header->total_snaps - ret;
+		dev->read_only = 1;
+	}
+
+	ret = 0;
+done:
+	up_write(&dev->header_rwsem);
+	return ret;
+}
+
+static void rbd_header_free(struct rbd_image_header *header)
+{
+	kfree(header->snapc);
+	kfree(header->snap_names);
+	kfree(header->snap_sizes);
+}
+
+/*
+ * get the actual striped segment name, offset and length
+ */
+static u64 rbd_get_segment(struct rbd_image_header *header,
+			   const char *block_name,
+			   u64 ofs, u64 len,
+			   char *seg_name, u64 *segofs)
+{
+	u64 seg = ofs >> header->obj_order;
+
+	if (seg_name)
+		snprintf(seg_name, RBD_MAX_SEG_NAME_LEN,
+			 "%s.%012llx", block_name, seg);
+
+	ofs = ofs & ((1 << header->obj_order) - 1);
+	len = min_t(u64, len, (1 << header->obj_order) - ofs);
+
+	if (segofs)
+		*segofs = ofs;
+
+	return len;
+}
+
+static int rbd_get_num_segments(struct rbd_image_header *header,
+				u64 ofs, u64 len)
+{
+	u64 start_seg = ofs >> header->obj_order;
+	u64 end_seg = (ofs + len - 1) >> header->obj_order;
+	return end_seg - start_seg + 1;
+}
+
+/*
+ * returns the size of an object in the image
+ */
+static u64 rbd_obj_bytes(struct rbd_image_header *header)
+{
+	return 1 << header->obj_order;
+}
+
+/*
+ * bio helpers
+ */
+
+static void bio_chain_put(struct bio *chain)
+{
+	struct bio *tmp;
+
+	while (chain) {
+		tmp = chain;
+		chain = chain->bi_next;
+		bio_put(tmp);
+	}
+}
+
+/*
+ * zeros a bio chain, starting at specific offset
+ */
+static void zero_bio_chain(struct bio *chain, int start_ofs)
+{
+	struct bio_vec *bv;
+	unsigned long flags;
+	void *buf;
+	int i;
+	int pos = 0;
+
+	while (chain) {
+		bio_for_each_segment(bv, chain, i) {
+			if (pos + bv->bv_len > start_ofs) {
+				int remainder = max(start_ofs - pos, 0);
+				buf = bvec_kmap_irq(bv, &flags);
+				memset(buf + remainder, 0,
+				       bv->bv_len - remainder);
+				bvec_kunmap_irq(buf, &flags);
+			}
+			pos += bv->bv_len;
+		}
+
+		chain = chain->bi_next;
+	}
+}
+
+/*
+ * bio_chain_clone - clone a chain of bios up to a certain length.
+ * might return a bio_pair that will need to be released.
+ */
+static struct bio *bio_chain_clone(struct bio **old, struct bio **next,
+				   struct bio_pair **bp,
+				   int len, gfp_t gfpmask)
+{
+	struct bio *tmp, *old_chain = *old, *new_chain = NULL, *tail = NULL;
+	int total = 0;
+
+	if (*bp) {
+		bio_pair_release(*bp);
+		*bp = NULL;
+	}
+
+	while (old_chain && (total < len)) {
+		tmp = bio_kmalloc(gfpmask, old_chain->bi_max_vecs);
+		if (!tmp)
+			goto err_out;
+
+		if (total + old_chain->bi_size > len) {
+			struct bio_pair *bp;
+
+			/*
+			 * this split can only happen with a single paged bio,
+			 * split_bio will BUG_ON if this is not the case
+			 */
+			dout("bio_chain_clone split! total=%d remaining=%d"
+			     "bi_size=%d\n",
+			     (int)total, (int)len-total,
+			     (int)old_chain->bi_size);
+
+			/* split the bio. We'll release it either in the next
+			   call, or it will have to be released outside */
+			bp = bio_split(old_chain, (len - total) / SECTOR_SIZE);
+			if (!bp)
+				goto err_out;
+
+			__bio_clone(tmp, &bp->bio1);
+
+			*next = &bp->bio2;
+		} else {
+			__bio_clone(tmp, old_chain);
+			*next = old_chain->bi_next;
+		}
+
+		tmp->bi_bdev = NULL;
+		gfpmask &= ~__GFP_WAIT;
+		tmp->bi_next = NULL;
+
+		if (!new_chain) {
+			new_chain = tail = tmp;
+		} else {
+			tail->bi_next = tmp;
+			tail = tmp;
+		}
+		old_chain = old_chain->bi_next;
+
+		total += tmp->bi_size;
+	}
+
+	BUG_ON(total < len);
+
+	if (tail)
+		tail->bi_next = NULL;
+
+	*old = old_chain;
+
+	return new_chain;
+
+err_out:
+	dout("bio_chain_clone with err\n");
+	bio_chain_put(new_chain);
+	return NULL;
+}
+
+/*
+ * helpers for osd request op vectors.
+ */
+static int rbd_create_rw_ops(struct ceph_osd_req_op **ops,
+			    int num_ops,
+			    int opcode,
+			    u32 payload_len)
+{
+	*ops = kzalloc(sizeof(struct ceph_osd_req_op) * (num_ops + 1),
+		       GFP_NOIO);
+	if (!*ops)
+		return -ENOMEM;
+	(*ops)[0].op = opcode;
+	/*
+	 * op extent offset and length will be set later on
+	 * in calc_raw_layout()
+	 */
+	(*ops)[0].payload_len = payload_len;
+	return 0;
+}
+
+static void rbd_destroy_ops(struct ceph_osd_req_op *ops)
+{
+	kfree(ops);
+}
+
+static void rbd_coll_end_req_index(struct request *rq,
+				   struct rbd_req_coll *coll,
+				   int index,
+				   int ret, u64 len)
+{
+	struct request_queue *q;
+	int min, max, i;
+
+	dout("rbd_coll_end_req_index %p index %d ret %d len %lld\n",
+	     coll, index, ret, len);
+
+	if (!rq)
+		return;
+
+	if (!coll) {
+		blk_end_request(rq, ret, len);
+		return;
+	}
+
+	q = rq->q;
+
+	spin_lock_irq(q->queue_lock);
+	coll->status[index].done = 1;
+	coll->status[index].rc = ret;
+	coll->status[index].bytes = len;
+	max = min = coll->num_done;
+	while (max < coll->total && coll->status[max].done)
+		max++;
+
+	for (i = min; i<max; i++) {
+		__blk_end_request(rq, coll->status[i].rc,
+				  coll->status[i].bytes);
+		coll->num_done++;
+		kref_put(&coll->kref, rbd_coll_release);
+	}
+	spin_unlock_irq(q->queue_lock);
+}
+
+static void rbd_coll_end_req(struct rbd_request *req,
+			     int ret, u64 len)
+{
+	rbd_coll_end_req_index(req->rq, req->coll, req->coll_index, ret, len);
+}
+
+/*
+ * Send ceph osd request
+ */
+static int rbd_do_request(struct request *rq,
+			  struct rbd_device *dev,
+			  struct ceph_snap_context *snapc,
+			  u64 snapid,
+			  const char *obj, u64 ofs, u64 len,
+			  struct bio *bio,
+			  struct page **pages,
+			  int num_pages,
+			  int flags,
+			  struct ceph_osd_req_op *ops,
+			  int num_reply,
+			  struct rbd_req_coll *coll,
+			  int coll_index,
+			  void (*rbd_cb)(struct ceph_osd_request *req,
+					 struct ceph_msg *msg),
+			  struct ceph_osd_request **linger_req,
+			  u64 *ver)
+{
+	struct ceph_osd_request *req;
+	struct ceph_file_layout *layout;
+	int ret;
+	u64 bno;
+	struct timespec mtime = CURRENT_TIME;
+	struct rbd_request *req_data;
+	struct ceph_osd_request_head *reqhead;
+	struct ceph_osd_client *osdc;
+
+	req_data = kzalloc(sizeof(*req_data), GFP_NOIO);
+	if (!req_data) {
+		if (coll)
+			rbd_coll_end_req_index(rq, coll, coll_index,
+					       -ENOMEM, len);
+		return -ENOMEM;
+	}
+
+	if (coll) {
+		req_data->coll = coll;
+		req_data->coll_index = coll_index;
+	}
+
+	dout("rbd_do_request obj=%s ofs=%lld len=%lld\n", obj, len, ofs);
+
+	down_read(&dev->header_rwsem);
+
+	osdc = &dev->rbd_client->client->osdc;
+	req = ceph_osdc_alloc_request(osdc, flags, snapc, ops,
+					false, GFP_NOIO, pages, bio);
+	if (!req) {
+		up_read(&dev->header_rwsem);
+		ret = -ENOMEM;
+		goto done_pages;
+	}
+
+	req->r_callback = rbd_cb;
+
+	req_data->rq = rq;
+	req_data->bio = bio;
+	req_data->pages = pages;
+	req_data->len = len;
+
+	req->r_priv = req_data;
+
+	reqhead = req->r_request->front.iov_base;
+	reqhead->snapid = cpu_to_le64(CEPH_NOSNAP);
+
+	strncpy(req->r_oid, obj, sizeof(req->r_oid));
+	req->r_oid_len = strlen(req->r_oid);
+
+	layout = &req->r_file_layout;
+	memset(layout, 0, sizeof(*layout));
+	layout->fl_stripe_unit = cpu_to_le32(1 << RBD_MAX_OBJ_ORDER);
+	layout->fl_stripe_count = cpu_to_le32(1);
+	layout->fl_object_size = cpu_to_le32(1 << RBD_MAX_OBJ_ORDER);
+	layout->fl_pg_preferred = cpu_to_le32(-1);
+	layout->fl_pg_pool = cpu_to_le32(dev->poolid);
+	ceph_calc_raw_layout(osdc, layout, snapid, ofs, &len, &bno,
+				req, ops);
+
+	ceph_osdc_build_request(req, ofs, &len,
+				ops,
+				snapc,
+				&mtime,
+				req->r_oid, req->r_oid_len);
+	up_read(&dev->header_rwsem);
+
+	if (linger_req) {
+		ceph_osdc_set_request_linger(osdc, req);
+		*linger_req = req;
+	}
+
+	ret = ceph_osdc_start_request(osdc, req, false);
+	if (ret < 0)
+		goto done_err;
+
+	if (!rbd_cb) {
+		ret = ceph_osdc_wait_request(osdc, req);
+		if (ver)
+			*ver = le64_to_cpu(req->r_reassert_version.version);
+		dout("reassert_ver=%lld\n",
+		     le64_to_cpu(req->r_reassert_version.version));
+		ceph_osdc_put_request(req);
+	}
+	return ret;
+
+done_err:
+	bio_chain_put(req_data->bio);
+	ceph_osdc_put_request(req);
+done_pages:
+	rbd_coll_end_req(req_data, ret, len);
+	kfree(req_data);
+	return ret;
+}
+
+/*
+ * Ceph osd op callback
+ */
+static void rbd_req_cb(struct ceph_osd_request *req, struct ceph_msg *msg)
+{
+	struct rbd_request *req_data = req->r_priv;
+	struct ceph_osd_reply_head *replyhead;
+	struct ceph_osd_op *op;
+	__s32 rc;
+	u64 bytes;
+	int read_op;
+
+	/* parse reply */
+	replyhead = msg->front.iov_base;
+	WARN_ON(le32_to_cpu(replyhead->num_ops) == 0);
+	op = (void *)(replyhead + 1);
+	rc = le32_to_cpu(replyhead->result);
+	bytes = le64_to_cpu(op->extent.length);
+	read_op = (le32_to_cpu(op->op) == CEPH_OSD_OP_READ);
+
+	dout("rbd_req_cb bytes=%lld readop=%d rc=%d\n", bytes, read_op, rc);
+
+	if (rc == -ENOENT && read_op) {
+		zero_bio_chain(req_data->bio, 0);
+		rc = 0;
+	} else if (rc == 0 && read_op && bytes < req_data->len) {
+		zero_bio_chain(req_data->bio, bytes);
+		bytes = req_data->len;
+	}
+
+	rbd_coll_end_req(req_data, rc, bytes);
+
+	if (req_data->bio)
+		bio_chain_put(req_data->bio);
+
+	ceph_osdc_put_request(req);
+	kfree(req_data);
+}
+
+static void rbd_simple_req_cb(struct ceph_osd_request *req, struct ceph_msg *msg)
+{
+	ceph_osdc_put_request(req);
+}
+
+/*
+ * Do a synchronous ceph osd operation
+ */
+static int rbd_req_sync_op(struct rbd_device *dev,
+			   struct ceph_snap_context *snapc,
+			   u64 snapid,
+			   int opcode,
+			   int flags,
+			   struct ceph_osd_req_op *orig_ops,
+			   int num_reply,
+			   const char *obj,
+			   u64 ofs, u64 len,
+			   char *buf,
+			   struct ceph_osd_request **linger_req,
+			   u64 *ver)
+{
+	int ret;
+	struct page **pages;
+	int num_pages;
+	struct ceph_osd_req_op *ops = orig_ops;
+	u32 payload_len;
+
+	num_pages = calc_pages_for(ofs , len);
+	pages = ceph_alloc_page_vector(num_pages, GFP_KERNEL);
+	if (IS_ERR(pages))
+		return PTR_ERR(pages);
+
+	if (!orig_ops) {
+		payload_len = (flags & CEPH_OSD_FLAG_WRITE ? len : 0);
+		ret = rbd_create_rw_ops(&ops, 1, opcode, payload_len);
+		if (ret < 0)
+			goto done;
+
+		if ((flags & CEPH_OSD_FLAG_WRITE) && buf) {
+			ret = ceph_copy_to_page_vector(pages, buf, ofs, len);
+			if (ret < 0)
+				goto done_ops;
+		}
+	}
+
+	ret = rbd_do_request(NULL, dev, snapc, snapid,
+			  obj, ofs, len, NULL,
+			  pages, num_pages,
+			  flags,
+			  ops,
+			  2,
+			  NULL, 0,
+			  NULL,
+			  linger_req, ver);
+	if (ret < 0)
+		goto done_ops;
+
+	if ((flags & CEPH_OSD_FLAG_READ) && buf)
+		ret = ceph_copy_from_page_vector(pages, buf, ofs, ret);
+
+done_ops:
+	if (!orig_ops)
+		rbd_destroy_ops(ops);
+done:
+	ceph_release_page_vector(pages, num_pages);
+	return ret;
+}
+
+/*
+ * Do an asynchronous ceph osd operation
+ */
+static int rbd_do_op(struct request *rq,
+		     struct rbd_device *rbd_dev ,
+		     struct ceph_snap_context *snapc,
+		     u64 snapid,
+		     int opcode, int flags, int num_reply,
+		     u64 ofs, u64 len,
+		     struct bio *bio,
+		     struct rbd_req_coll *coll,
+		     int coll_index)
+{
+	char *seg_name;
+	u64 seg_ofs;
+	u64 seg_len;
+	int ret;
+	struct ceph_osd_req_op *ops;
+	u32 payload_len;
+
+	seg_name = kmalloc(RBD_MAX_SEG_NAME_LEN + 1, GFP_NOIO);
+	if (!seg_name)
+		return -ENOMEM;
+
+	seg_len = rbd_get_segment(&rbd_dev->header,
+				  rbd_dev->header.block_name,
+				  ofs, len,
+				  seg_name, &seg_ofs);
+
+	payload_len = (flags & CEPH_OSD_FLAG_WRITE ? seg_len : 0);
+
+	ret = rbd_create_rw_ops(&ops, 1, opcode, payload_len);
+	if (ret < 0)
+		goto done;
+
+	/* we've taken care of segment sizes earlier when we
+	   cloned the bios. We should never have a segment
+	   truncated at this point */
+	BUG_ON(seg_len < len);
+
+	ret = rbd_do_request(rq, rbd_dev, snapc, snapid,
+			     seg_name, seg_ofs, seg_len,
+			     bio,
+			     NULL, 0,
+			     flags,
+			     ops,
+			     num_reply,
+			     coll, coll_index,
+			     rbd_req_cb, 0, NULL);
+
+	rbd_destroy_ops(ops);
+done:
+	kfree(seg_name);
+	return ret;
+}
+
+/*
+ * Request async osd write
+ */
+static int rbd_req_write(struct request *rq,
+			 struct rbd_device *rbd_dev,
+			 struct ceph_snap_context *snapc,
+			 u64 ofs, u64 len,
+			 struct bio *bio,
+			 struct rbd_req_coll *coll,
+			 int coll_index)
+{
+	return rbd_do_op(rq, rbd_dev, snapc, CEPH_NOSNAP,
+			 CEPH_OSD_OP_WRITE,
+			 CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
+			 2,
+			 ofs, len, bio, coll, coll_index);
+}
+
+/*
+ * Request async osd read
+ */
+static int rbd_req_read(struct request *rq,
+			 struct rbd_device *rbd_dev,
+			 u64 snapid,
+			 u64 ofs, u64 len,
+			 struct bio *bio,
+			 struct rbd_req_coll *coll,
+			 int coll_index)
+{
+	return rbd_do_op(rq, rbd_dev, NULL,
+			 (snapid ? snapid : CEPH_NOSNAP),
+			 CEPH_OSD_OP_READ,
+			 CEPH_OSD_FLAG_READ,
+			 2,
+			 ofs, len, bio, coll, coll_index);
+}
+
+/*
+ * Request sync osd read
+ */
+static int rbd_req_sync_read(struct rbd_device *dev,
+			  struct ceph_snap_context *snapc,
+			  u64 snapid,
+			  const char *obj,
+			  u64 ofs, u64 len,
+			  char *buf,
+			  u64 *ver)
+{
+	return rbd_req_sync_op(dev, NULL,
+			       (snapid ? snapid : CEPH_NOSNAP),
+			       CEPH_OSD_OP_READ,
+			       CEPH_OSD_FLAG_READ,
+			       NULL,
+			       1, obj, ofs, len, buf, NULL, ver);
+}
+
+/*
+ * Request sync osd watch
+ */
+static int rbd_req_sync_notify_ack(struct rbd_device *dev,
+				   u64 ver,
+				   u64 notify_id,
+				   const char *obj)
+{
+	struct ceph_osd_req_op *ops;
+	struct page **pages = NULL;
+	int ret;
+
+	ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_NOTIFY_ACK, 0);
+	if (ret < 0)
+		return ret;
+
+	ops[0].watch.ver = cpu_to_le64(dev->header.obj_version);
+	ops[0].watch.cookie = notify_id;
+	ops[0].watch.flag = 0;
+
+	ret = rbd_do_request(NULL, dev, NULL, CEPH_NOSNAP,
+			  obj, 0, 0, NULL,
+			  pages, 0,
+			  CEPH_OSD_FLAG_READ,
+			  ops,
+			  1,
+			  NULL, 0,
+			  rbd_simple_req_cb, 0, NULL);
+
+	rbd_destroy_ops(ops);
+	return ret;
+}
+
+static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
+{
+	struct rbd_device *dev = (struct rbd_device *)data;
+	int rc;
+
+	if (!dev)
+		return;
+
+	dout("rbd_watch_cb %s notify_id=%lld opcode=%d\n", dev->obj_md_name,
+		notify_id, (int)opcode);
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+	rc = __rbd_update_snaps(dev);
+	mutex_unlock(&ctl_mutex);
+	if (rc)
+		pr_warning(RBD_DRV_NAME "%d got notification but failed to "
+			   " update snaps: %d\n", dev->major, rc);
+
+	rbd_req_sync_notify_ack(dev, ver, notify_id, dev->obj_md_name);
+}
+
+/*
+ * Request sync osd watch
+ */
+static int rbd_req_sync_watch(struct rbd_device *dev,
+			      const char *obj,
+			      u64 ver)
+{
+	struct ceph_osd_req_op *ops;
+	struct ceph_osd_client *osdc = &dev->rbd_client->client->osdc;
+
+	int ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_WATCH, 0);
+	if (ret < 0)
+		return ret;
+
+	ret = ceph_osdc_create_event(osdc, rbd_watch_cb, 0,
+				     (void *)dev, &dev->watch_event);
+	if (ret < 0)
+		goto fail;
+
+	ops[0].watch.ver = cpu_to_le64(ver);
+	ops[0].watch.cookie = cpu_to_le64(dev->watch_event->cookie);
+	ops[0].watch.flag = 1;
+
+	ret = rbd_req_sync_op(dev, NULL,
+			      CEPH_NOSNAP,
+			      0,
+			      CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
+			      ops,
+			      1, obj, 0, 0, NULL,
+			      &dev->watch_request, NULL);
+
+	if (ret < 0)
+		goto fail_event;
+
+	rbd_destroy_ops(ops);
+	return 0;
+
+fail_event:
+	ceph_osdc_cancel_event(dev->watch_event);
+	dev->watch_event = NULL;
+fail:
+	rbd_destroy_ops(ops);
+	return ret;
+}
+
+/*
+ * Request sync osd unwatch
+ */
+static int rbd_req_sync_unwatch(struct rbd_device *dev,
+				const char *obj)
+{
+	struct ceph_osd_req_op *ops;
+
+	int ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_WATCH, 0);
+	if (ret < 0)
+		return ret;
+
+	ops[0].watch.ver = 0;
+	ops[0].watch.cookie = cpu_to_le64(dev->watch_event->cookie);
+	ops[0].watch.flag = 0;
+
+	ret = rbd_req_sync_op(dev, NULL,
+			      CEPH_NOSNAP,
+			      0,
+			      CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
+			      ops,
+			      1, obj, 0, 0, NULL, NULL, NULL);
+
+	rbd_destroy_ops(ops);
+	ceph_osdc_cancel_event(dev->watch_event);
+	dev->watch_event = NULL;
+	return ret;
+}
+
+struct rbd_notify_info {
+	struct rbd_device *dev;
+};
+
+static void rbd_notify_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
+{
+	struct rbd_device *dev = (struct rbd_device *)data;
+	if (!dev)
+		return;
+
+	dout("rbd_notify_cb %s notify_id=%lld opcode=%d\n", dev->obj_md_name,
+		notify_id, (int)opcode);
+}
+
+/*
+ * Request sync osd notify
+ */
+static int rbd_req_sync_notify(struct rbd_device *dev,
+		          const char *obj)
+{
+	struct ceph_osd_req_op *ops;
+	struct ceph_osd_client *osdc = &dev->rbd_client->client->osdc;
+	struct ceph_osd_event *event;
+	struct rbd_notify_info info;
+	int payload_len = sizeof(u32) + sizeof(u32);
+	int ret;
+
+	ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_NOTIFY, payload_len);
+	if (ret < 0)
+		return ret;
+
+	info.dev = dev;
+
+	ret = ceph_osdc_create_event(osdc, rbd_notify_cb, 1,
+				     (void *)&info, &event);
+	if (ret < 0)
+		goto fail;
+
+	ops[0].watch.ver = 1;
+	ops[0].watch.flag = 1;
+	ops[0].watch.cookie = event->cookie;
+	ops[0].watch.prot_ver = RADOS_NOTIFY_VER;
+	ops[0].watch.timeout = 12;
+
+	ret = rbd_req_sync_op(dev, NULL,
+			       CEPH_NOSNAP,
+			       0,
+			       CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
+			       ops,
+			       1, obj, 0, 0, NULL, NULL, NULL);
+	if (ret < 0)
+		goto fail_event;
+
+	ret = ceph_osdc_wait_event(event, CEPH_OSD_TIMEOUT_DEFAULT);
+	dout("ceph_osdc_wait_event returned %d\n", ret);
+	rbd_destroy_ops(ops);
+	return 0;
+
+fail_event:
+	ceph_osdc_cancel_event(event);
+fail:
+	rbd_destroy_ops(ops);
+	return ret;
+}
+
+/*
+ * Request sync osd read
+ */
+static int rbd_req_sync_exec(struct rbd_device *dev,
+			     const char *obj,
+			     const char *cls,
+			     const char *method,
+			     const char *data,
+			     int len,
+			     u64 *ver)
+{
+	struct ceph_osd_req_op *ops;
+	int cls_len = strlen(cls);
+	int method_len = strlen(method);
+	int ret = rbd_create_rw_ops(&ops, 1, CEPH_OSD_OP_CALL,
+				    cls_len + method_len + len);
+	if (ret < 0)
+		return ret;
+
+	ops[0].cls.class_name = cls;
+	ops[0].cls.class_len = (__u8)cls_len;
+	ops[0].cls.method_name = method;
+	ops[0].cls.method_len = (__u8)method_len;
+	ops[0].cls.argc = 0;
+	ops[0].cls.indata = data;
+	ops[0].cls.indata_len = len;
+
+	ret = rbd_req_sync_op(dev, NULL,
+			       CEPH_NOSNAP,
+			       0,
+			       CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK,
+			       ops,
+			       1, obj, 0, 0, NULL, NULL, ver);
+
+	rbd_destroy_ops(ops);
+
+	dout("cls_exec returned %d\n", ret);
+	return ret;
+}
+
+static struct rbd_req_coll *rbd_alloc_coll(int num_reqs)
+{
+	struct rbd_req_coll *coll =
+			kzalloc(sizeof(struct rbd_req_coll) +
+			        sizeof(struct rbd_req_status) * num_reqs,
+				GFP_ATOMIC);
+
+	if (!coll)
+		return NULL;
+	coll->total = num_reqs;
+	kref_init(&coll->kref);
+	return coll;
+}
+
+/*
+ * block device queue callback
+ */
+static void rbd_rq_fn(struct request_queue *q)
+{
+	struct rbd_device *rbd_dev = q->queuedata;
+	struct request *rq;
+	struct bio_pair *bp = NULL;
+
+	while ((rq = blk_fetch_request(q))) {
+		struct bio *bio;
+		struct bio *rq_bio, *next_bio = NULL;
+		bool do_write;
+		int size, op_size = 0;
+		u64 ofs;
+		int num_segs, cur_seg = 0;
+		struct rbd_req_coll *coll;
+
+		/* peek at request from block layer */
+		if (!rq)
+			break;
+
+		dout("fetched request\n");
+
+		/* filter out block requests we don't understand */
+		if ((rq->cmd_type != REQ_TYPE_FS)) {
+			__blk_end_request_all(rq, 0);
+			continue;
+		}
+
+		/* deduce our operation (read, write) */
+		do_write = (rq_data_dir(rq) == WRITE);
+
+		size = blk_rq_bytes(rq);
+		ofs = blk_rq_pos(rq) * SECTOR_SIZE;
+		rq_bio = rq->bio;
+		if (do_write && rbd_dev->read_only) {
+			__blk_end_request_all(rq, -EROFS);
+			continue;
+		}
+
+		spin_unlock_irq(q->queue_lock);
+
+		dout("%s 0x%x bytes at 0x%llx\n",
+		     do_write ? "write" : "read",
+		     size, blk_rq_pos(rq) * SECTOR_SIZE);
+
+		num_segs = rbd_get_num_segments(&rbd_dev->header, ofs, size);
+		coll = rbd_alloc_coll(num_segs);
+		if (!coll) {
+			spin_lock_irq(q->queue_lock);
+			__blk_end_request_all(rq, -ENOMEM);
+			continue;
+		}
+
+		do {
+			/* a bio clone to be passed down to OSD req */
+			dout("rq->bio->bi_vcnt=%d\n", rq->bio->bi_vcnt);
+			op_size = rbd_get_segment(&rbd_dev->header,
+						  rbd_dev->header.block_name,
+						  ofs, size,
+						  NULL, NULL);
+			kref_get(&coll->kref);
+			bio = bio_chain_clone(&rq_bio, &next_bio, &bp,
+					      op_size, GFP_ATOMIC);
+			if (!bio) {
+				rbd_coll_end_req_index(rq, coll, cur_seg,
+						       -ENOMEM, op_size);
+				goto next_seg;
+			}
+
+
+			/* init OSD command: write or read */
+			if (do_write)
+				rbd_req_write(rq, rbd_dev,
+					      rbd_dev->header.snapc,
+					      ofs,
+					      op_size, bio,
+					      coll, cur_seg);
+			else
+				rbd_req_read(rq, rbd_dev,
+					     cur_snap_id(rbd_dev),
+					     ofs,
+					     op_size, bio,
+					     coll, cur_seg);
+
+next_seg:
+			size -= op_size;
+			ofs += op_size;
+
+			cur_seg++;
+			rq_bio = next_bio;
+		} while (size > 0);
+		kref_put(&coll->kref, rbd_coll_release);
+
+		if (bp)
+			bio_pair_release(bp);
+		spin_lock_irq(q->queue_lock);
+	}
+}
+
+/*
+ * a queue callback. Makes sure that we don't create a bio that spans across
+ * multiple osd objects. One exception would be with a single page bios,
+ * which we handle later at bio_chain_clone
+ */
+static int rbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
+			  struct bio_vec *bvec)
+{
+	struct rbd_device *rbd_dev = q->queuedata;
+	unsigned int chunk_sectors;
+	sector_t sector;
+	unsigned int bio_sectors;
+	int max;
+
+	chunk_sectors = 1 << (rbd_dev->header.obj_order - SECTOR_SHIFT);
+	sector = bmd->bi_sector + get_start_sect(bmd->bi_bdev);
+	bio_sectors = bmd->bi_size >> SECTOR_SHIFT;
+
+	max =  (chunk_sectors - ((sector & (chunk_sectors - 1))
+				 + bio_sectors)) << SECTOR_SHIFT;
+	if (max < 0)
+		max = 0; /* bio_add cannot handle a negative return */
+	if (max <= bvec->bv_len && bio_sectors == 0)
+		return bvec->bv_len;
+	return max;
+}
+
+static void rbd_free_disk(struct rbd_device *rbd_dev)
+{
+	struct gendisk *disk = rbd_dev->disk;
+
+	if (!disk)
+		return;
+
+	rbd_header_free(&rbd_dev->header);
+
+	if (disk->flags & GENHD_FL_UP)
+		del_gendisk(disk);
+	if (disk->queue)
+		blk_cleanup_queue(disk->queue);
+	put_disk(disk);
+}
+
+/*
+ * reload the ondisk the header 
+ */
+static int rbd_read_header(struct rbd_device *rbd_dev,
+			   struct rbd_image_header *header)
+{
+	ssize_t rc;
+	struct rbd_image_header_ondisk *dh;
+	int snap_count = 0;
+	u64 ver;
+	size_t len;
+
+	/*
+	 * First reads the fixed-size header to determine the number
+	 * of snapshots, then re-reads it, along with all snapshot
+	 * records as well as their stored names.
+	 */
+	len = sizeof (*dh);
+	while (1) {
+		dh = kmalloc(len, GFP_KERNEL);
+		if (!dh)
+			return -ENOMEM;
+
+		rc = rbd_req_sync_read(rbd_dev,
+				       NULL, CEPH_NOSNAP,
+				       rbd_dev->obj_md_name,
+				       0, len,
+				       (char *)dh, &ver);
+		if (rc < 0)
+			goto out_dh;
+
+		rc = rbd_header_from_disk(header, dh, snap_count, GFP_KERNEL);
+		if (rc < 0) {
+			if (rc == -ENXIO)
+				pr_warning("unrecognized header format"
+					   " for image %s", rbd_dev->obj);
+			goto out_dh;
+		}
+
+		if (snap_count == header->total_snaps)
+			break;
+
+		snap_count = header->total_snaps;
+		len = sizeof (*dh) +
+			snap_count * sizeof(struct rbd_image_snap_ondisk) +
+			header->snap_names_len;
+
+		rbd_header_free(header);
+		kfree(dh);
+	}
+	header->obj_version = ver;
+
+out_dh:
+	kfree(dh);
+	return rc;
+}
+
+/*
+ * create a snapshot
+ */
+static int rbd_header_add_snap(struct rbd_device *dev,
+			       const char *snap_name,
+			       gfp_t gfp_flags)
+{
+	int name_len = strlen(snap_name);
+	u64 new_snapid;
+	int ret;
+	void *data, *p, *e;
+	u64 ver;
+	struct ceph_mon_client *monc;
+
+	/* we should create a snapshot only if we're pointing at the head */
+	if (dev->cur_snap)
+		return -EINVAL;
+
+	monc = &dev->rbd_client->client->monc;
+	ret = ceph_monc_create_snapid(monc, dev->poolid, &new_snapid);
+	dout("created snapid=%lld\n", new_snapid);
+	if (ret < 0)
+		return ret;
+
+	data = kmalloc(name_len + 16, gfp_flags);
+	if (!data)
+		return -ENOMEM;
+
+	p = data;
+	e = data + name_len + 16;
+
+	ceph_encode_string_safe(&p, e, snap_name, name_len, bad);
+	ceph_encode_64_safe(&p, e, new_snapid, bad);
+
+	ret = rbd_req_sync_exec(dev, dev->obj_md_name, "rbd", "snap_add",
+				data, p - data, &ver);
+
+	kfree(data);
+
+	if (ret < 0)
+		return ret;
+
+	dev->header.snapc->seq =  new_snapid;
+
+	return 0;
+bad:
+	return -ERANGE;
+}
+
+static void __rbd_remove_all_snaps(struct rbd_device *rbd_dev)
+{
+	struct rbd_snap *snap;
+
+	while (!list_empty(&rbd_dev->snaps)) {
+		snap = list_first_entry(&rbd_dev->snaps, struct rbd_snap, node);
+		__rbd_remove_snap_dev(rbd_dev, snap);
+	}
+}
+
+/*
+ * only read the first part of the ondisk header, without the snaps info
+ */
+static int __rbd_update_snaps(struct rbd_device *rbd_dev)
+{
+	int ret;
+	struct rbd_image_header h;
+	u64 snap_seq;
+	int follow_seq = 0;
+
+	ret = rbd_read_header(rbd_dev, &h);
+	if (ret < 0)
+		return ret;
+
+	/* resized? */
+	set_capacity(rbd_dev->disk, h.image_size / SECTOR_SIZE);
+
+	down_write(&rbd_dev->header_rwsem);
+
+	snap_seq = rbd_dev->header.snapc->seq;
+	if (rbd_dev->header.total_snaps &&
+	    rbd_dev->header.snapc->snaps[0] == snap_seq)
+		/* pointing at the head, will need to follow that
+		   if head moves */
+		follow_seq = 1;
+
+	kfree(rbd_dev->header.snapc);
+	kfree(rbd_dev->header.snap_names);
+	kfree(rbd_dev->header.snap_sizes);
+
+	rbd_dev->header.total_snaps = h.total_snaps;
+	rbd_dev->header.snapc = h.snapc;
+	rbd_dev->header.snap_names = h.snap_names;
+	rbd_dev->header.snap_names_len = h.snap_names_len;
+	rbd_dev->header.snap_sizes = h.snap_sizes;
+	if (follow_seq)
+		rbd_dev->header.snapc->seq = rbd_dev->header.snapc->snaps[0];
+	else
+		rbd_dev->header.snapc->seq = snap_seq;
+
+	ret = __rbd_init_snaps_header(rbd_dev);
+
+	up_write(&rbd_dev->header_rwsem);
+
+	return ret;
+}
+
+static int rbd_init_disk(struct rbd_device *rbd_dev)
+{
+	struct gendisk *disk;
+	struct request_queue *q;
+	int rc;
+	u64 segment_size;
+	u64 total_size = 0;
+
+	/* contact OSD, request size info about the object being mapped */
+	rc = rbd_read_header(rbd_dev, &rbd_dev->header);
+	if (rc)
+		return rc;
+
+	/* no need to lock here, as rbd_dev is not registered yet */
+	rc = __rbd_init_snaps_header(rbd_dev);
+	if (rc)
+		return rc;
+
+	rc = rbd_header_set_snap(rbd_dev, &total_size);
+	if (rc)
+		return rc;
+
+	/* create gendisk info */
+	rc = -ENOMEM;
+	disk = alloc_disk(RBD_MINORS_PER_MAJOR);
+	if (!disk)
+		goto out;
+
+	snprintf(disk->disk_name, sizeof(disk->disk_name), RBD_DRV_NAME "%d",
+		 rbd_dev->id);
+	disk->major = rbd_dev->major;
+	disk->first_minor = 0;
+	disk->fops = &rbd_bd_ops;
+	disk->private_data = rbd_dev;
+
+	/* init rq */
+	rc = -ENOMEM;
+	q = blk_init_queue(rbd_rq_fn, &rbd_dev->lock);
+	if (!q)
+		goto out_disk;
+
+	/* We use the default size, but let's be explicit about it. */
+	blk_queue_physical_block_size(q, SECTOR_SIZE);
+
+	/* set io sizes to object size */
+	segment_size = rbd_obj_bytes(&rbd_dev->header);
+	blk_queue_max_hw_sectors(q, segment_size / SECTOR_SIZE);
+	blk_queue_max_segment_size(q, segment_size);
+	blk_queue_io_min(q, segment_size);
+	blk_queue_io_opt(q, segment_size);
+
+	blk_queue_merge_bvec(q, rbd_merge_bvec);
+	disk->queue = q;
+
+	q->queuedata = rbd_dev;
+
+	rbd_dev->disk = disk;
+	rbd_dev->q = q;
+
+	/* finally, announce the disk to the world */
+	set_capacity(disk, total_size / SECTOR_SIZE);
+	add_disk(disk);
+
+	pr_info("%s: added with size 0x%llx\n",
+		disk->disk_name, (unsigned long long)total_size);
+	return 0;
+
+out_disk:
+	put_disk(disk);
+out:
+	return rc;
+}
+
+/*
+  sysfs
+*/
+
+static struct rbd_device *dev_to_rbd_dev(struct device *dev)
+{
+	return container_of(dev, struct rbd_device, dev);
+}
+
+static ssize_t rbd_size_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+
+	return sprintf(buf, "%llu\n", (unsigned long long)rbd_dev->header.image_size);
+}
+
+static ssize_t rbd_major_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+
+	return sprintf(buf, "%d\n", rbd_dev->major);
+}
+
+static ssize_t rbd_client_id_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+
+	return sprintf(buf, "client%lld\n",
+			ceph_client_id(rbd_dev->rbd_client->client));
+}
+
+static ssize_t rbd_pool_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+
+	return sprintf(buf, "%s\n", rbd_dev->pool_name);
+}
+
+static ssize_t rbd_name_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+
+	return sprintf(buf, "%s\n", rbd_dev->obj);
+}
+
+static ssize_t rbd_snap_show(struct device *dev,
+			     struct device_attribute *attr,
+			     char *buf)
+{
+	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+
+	return sprintf(buf, "%s\n", rbd_dev->snap_name);
+}
+
+static ssize_t rbd_image_refresh(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf,
+				 size_t size)
+{
+	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+	int rc;
+	int ret = size;
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+
+	rc = __rbd_update_snaps(rbd_dev);
+	if (rc < 0)
+		ret = rc;
+
+	mutex_unlock(&ctl_mutex);
+	return ret;
+}
+
+static DEVICE_ATTR(size, S_IRUGO, rbd_size_show, NULL);
+static DEVICE_ATTR(major, S_IRUGO, rbd_major_show, NULL);
+static DEVICE_ATTR(client_id, S_IRUGO, rbd_client_id_show, NULL);
+static DEVICE_ATTR(pool, S_IRUGO, rbd_pool_show, NULL);
+static DEVICE_ATTR(name, S_IRUGO, rbd_name_show, NULL);
+static DEVICE_ATTR(refresh, S_IWUSR, NULL, rbd_image_refresh);
+static DEVICE_ATTR(current_snap, S_IRUGO, rbd_snap_show, NULL);
+static DEVICE_ATTR(create_snap, S_IWUSR, NULL, rbd_snap_add);
+
+static struct attribute *rbd_attrs[] = {
+	&dev_attr_size.attr,
+	&dev_attr_major.attr,
+	&dev_attr_client_id.attr,
+	&dev_attr_pool.attr,
+	&dev_attr_name.attr,
+	&dev_attr_current_snap.attr,
+	&dev_attr_refresh.attr,
+	&dev_attr_create_snap.attr,
+	NULL
+};
+
+static struct attribute_group rbd_attr_group = {
+	.attrs = rbd_attrs,
+};
+
+static const struct attribute_group *rbd_attr_groups[] = {
+	&rbd_attr_group,
+	NULL
+};
+
+static void rbd_sysfs_dev_release(struct device *dev)
+{
+}
+
+static struct device_type rbd_device_type = {
+	.name		= "rbd",
+	.groups		= rbd_attr_groups,
+	.release	= rbd_sysfs_dev_release,
+};
+
+
+/*
+  sysfs - snapshots
+*/
+
+static ssize_t rbd_snap_size_show(struct device *dev,
+				  struct device_attribute *attr,
+				  char *buf)
+{
+	struct rbd_snap *snap = container_of(dev, struct rbd_snap, dev);
+
+	return sprintf(buf, "%zd\n", snap->size);
+}
+
+static ssize_t rbd_snap_id_show(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	struct rbd_snap *snap = container_of(dev, struct rbd_snap, dev);
+
+	return sprintf(buf, "%llu\n", (unsigned long long) snap->id);
+}
+
+static DEVICE_ATTR(snap_size, S_IRUGO, rbd_snap_size_show, NULL);
+static DEVICE_ATTR(snap_id, S_IRUGO, rbd_snap_id_show, NULL);
+
+static struct attribute *rbd_snap_attrs[] = {
+	&dev_attr_snap_size.attr,
+	&dev_attr_snap_id.attr,
+	NULL,
+};
+
+static struct attribute_group rbd_snap_attr_group = {
+	.attrs = rbd_snap_attrs,
+};
+
+static void rbd_snap_dev_release(struct device *dev)
+{
+	struct rbd_snap *snap = container_of(dev, struct rbd_snap, dev);
+	kfree(snap->name);
+	kfree(snap);
+}
+
+static const struct attribute_group *rbd_snap_attr_groups[] = {
+	&rbd_snap_attr_group,
+	NULL
+};
+
+static struct device_type rbd_snap_device_type = {
+	.groups		= rbd_snap_attr_groups,
+	.release	= rbd_snap_dev_release,
+};
+
+static void __rbd_remove_snap_dev(struct rbd_device *rbd_dev,
+				  struct rbd_snap *snap)
+{
+	list_del(&snap->node);
+	device_unregister(&snap->dev);
+}
+
+static int rbd_register_snap_dev(struct rbd_device *rbd_dev,
+				  struct rbd_snap *snap,
+				  struct device *parent)
+{
+	struct device *dev = &snap->dev;
+	int ret;
+
+	dev->type = &rbd_snap_device_type;
+	dev->parent = parent;
+	dev->release = rbd_snap_dev_release;
+	dev_set_name(dev, "snap_%s", snap->name);
+	ret = device_register(dev);
+
+	return ret;
+}
+
+static int __rbd_add_snap_dev(struct rbd_device *rbd_dev,
+			      int i, const char *name,
+			      struct rbd_snap **snapp)
+{
+	int ret;
+	struct rbd_snap *snap = kzalloc(sizeof(*snap), GFP_KERNEL);
+	if (!snap)
+		return -ENOMEM;
+	snap->name = kstrdup(name, GFP_KERNEL);
+	snap->size = rbd_dev->header.snap_sizes[i];
+	snap->id = rbd_dev->header.snapc->snaps[i];
+	if (device_is_registered(&rbd_dev->dev)) {
+		ret = rbd_register_snap_dev(rbd_dev, snap,
+					     &rbd_dev->dev);
+		if (ret < 0)
+			goto err;
+	}
+	*snapp = snap;
+	return 0;
+err:
+	kfree(snap->name);
+	kfree(snap);
+	return ret;
+}
+
+/*
+ * search for the previous snap in a null delimited string list
+ */
+const char *rbd_prev_snap_name(const char *name, const char *start)
+{
+	if (name < start + 2)
+		return NULL;
+
+	name -= 2;
+	while (*name) {
+		if (name == start)
+			return start;
+		name--;
+	}
+	return name + 1;
+}
+
+/*
+ * compare the old list of snapshots that we have to what's in the header
+ * and update it accordingly. Note that the header holds the snapshots
+ * in a reverse order (from newest to oldest) and we need to go from
+ * older to new so that we don't get a duplicate snap name when
+ * doing the process (e.g., removed snapshot and recreated a new
+ * one with the same name.
+ */
+static int __rbd_init_snaps_header(struct rbd_device *rbd_dev)
+{
+	const char *name, *first_name;
+	int i = rbd_dev->header.total_snaps;
+	struct rbd_snap *snap, *old_snap = NULL;
+	int ret;
+	struct list_head *p, *n;
+
+	first_name = rbd_dev->header.snap_names;
+	name = first_name + rbd_dev->header.snap_names_len;
+
+	list_for_each_prev_safe(p, n, &rbd_dev->snaps) {
+		u64 cur_id;
+
+		old_snap = list_entry(p, struct rbd_snap, node);
+
+		if (i)
+			cur_id = rbd_dev->header.snapc->snaps[i - 1];
+
+		if (!i || old_snap->id < cur_id) {
+			/* old_snap->id was skipped, thus was removed */
+			__rbd_remove_snap_dev(rbd_dev, old_snap);
+			continue;
+		}
+		if (old_snap->id == cur_id) {
+			/* we have this snapshot already */
+			i--;
+			name = rbd_prev_snap_name(name, first_name);
+			continue;
+		}
+		for (; i > 0;
+		     i--, name = rbd_prev_snap_name(name, first_name)) {
+			if (!name) {
+				WARN_ON(1);
+				return -EINVAL;
+			}
+			cur_id = rbd_dev->header.snapc->snaps[i];
+			/* snapshot removal? handle it above */
+			if (cur_id >= old_snap->id)
+				break;
+			/* a new snapshot */
+			ret = __rbd_add_snap_dev(rbd_dev, i - 1, name, &snap);
+			if (ret < 0)
+				return ret;
+
+			/* note that we add it backward so using n and not p */
+			list_add(&snap->node, n);
+			p = &snap->node;
+		}
+	}
+	/* we're done going over the old snap list, just add what's left */
+	for (; i > 0; i--) {
+		name = rbd_prev_snap_name(name, first_name);
+		if (!name) {
+			WARN_ON(1);
+			return -EINVAL;
+		}
+		ret = __rbd_add_snap_dev(rbd_dev, i - 1, name, &snap);
+		if (ret < 0)
+			return ret;
+		list_add(&snap->node, &rbd_dev->snaps);
+	}
+
+	return 0;
+}
+
+static int rbd_bus_add_dev(struct rbd_device *rbd_dev)
+{
+	int ret;
+	struct device *dev;
+	struct rbd_snap *snap;
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+	dev = &rbd_dev->dev;
+
+	dev->bus = &rbd_bus_type;
+	dev->type = &rbd_device_type;
+	dev->parent = &rbd_root_dev;
+	dev->release = rbd_dev_release;
+	dev_set_name(dev, "%d", rbd_dev->id);
+	ret = device_register(dev);
+	if (ret < 0)
+		goto out;
+
+	list_for_each_entry(snap, &rbd_dev->snaps, node) {
+		ret = rbd_register_snap_dev(rbd_dev, snap,
+					     &rbd_dev->dev);
+		if (ret < 0)
+			break;
+	}
+out:
+	mutex_unlock(&ctl_mutex);
+	return ret;
+}
+
+static void rbd_bus_del_dev(struct rbd_device *rbd_dev)
+{
+	device_unregister(&rbd_dev->dev);
+}
+
+static int rbd_init_watch_dev(struct rbd_device *rbd_dev)
+{
+	int ret, rc;
+
+	do {
+		ret = rbd_req_sync_watch(rbd_dev, rbd_dev->obj_md_name,
+					 rbd_dev->header.obj_version);
+		if (ret == -ERANGE) {
+			mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+			rc = __rbd_update_snaps(rbd_dev);
+			mutex_unlock(&ctl_mutex);
+			if (rc < 0)
+				return rc;
+		}
+	} while (ret == -ERANGE);
+
+	return ret;
+}
+
+static atomic64_t rbd_id_max = ATOMIC64_INIT(0);
+
+/*
+ * Get a unique rbd identifier for the given new rbd_dev, and add
+ * the rbd_dev to the global list.  The minimum rbd id is 1.
+ */
+static void rbd_id_get(struct rbd_device *rbd_dev)
+{
+	rbd_dev->id = atomic64_inc_return(&rbd_id_max);
+
+	spin_lock(&rbd_dev_list_lock);
+	list_add_tail(&rbd_dev->node, &rbd_dev_list);
+	spin_unlock(&rbd_dev_list_lock);
+}
+
+/*
+ * Remove an rbd_dev from the global list, and record that its
+ * identifier is no longer in use.
+ */
+static void rbd_id_put(struct rbd_device *rbd_dev)
+{
+	struct list_head *tmp;
+	int rbd_id = rbd_dev->id;
+	int max_id;
+
+	BUG_ON(rbd_id < 1);
+
+	spin_lock(&rbd_dev_list_lock);
+	list_del_init(&rbd_dev->node);
+
+	/*
+	 * If the id being "put" is not the current maximum, there
+	 * is nothing special we need to do.
+	 */
+	if (rbd_id != atomic64_read(&rbd_id_max)) {
+		spin_unlock(&rbd_dev_list_lock);
+		return;
+	}
+
+	/*
+	 * We need to update the current maximum id.  Search the
+	 * list to find out what it is.  We're more likely to find
+	 * the maximum at the end, so search the list backward.
+	 */
+	max_id = 0;
+	list_for_each_prev(tmp, &rbd_dev_list) {
+		struct rbd_device *rbd_dev;
+
+		rbd_dev = list_entry(tmp, struct rbd_device, node);
+		if (rbd_id > max_id)
+			max_id = rbd_id;
+	}
+	spin_unlock(&rbd_dev_list_lock);
+
+	/*
+	 * The max id could have been updated by rbd_id_get(), in
+	 * which case it now accurately reflects the new maximum.
+	 * Be careful not to overwrite the maximum value in that
+	 * case.
+	 */
+	atomic64_cmpxchg(&rbd_id_max, rbd_id, max_id);
+}
+
+/*
+ * Skips over white space at *buf, and updates *buf to point to the
+ * first found non-space character (if any). Returns the length of
+ * the token (string of non-white space characters) found.  Note
+ * that *buf must be terminated with '\0'.
+ */
+static inline size_t next_token(const char **buf)
+{
+        /*
+        * These are the characters that produce nonzero for
+        * isspace() in the "C" and "POSIX" locales.
+        */
+        const char *spaces = " \f\n\r\t\v";
+
+        *buf += strspn(*buf, spaces);	/* Find start of token */
+
+	return strcspn(*buf, spaces);   /* Return token length */
+}
+
+/*
+ * Finds the next token in *buf, and if the provided token buffer is
+ * big enough, copies the found token into it.  The result, if
+ * copied, is guaranteed to be terminated with '\0'.  Note that *buf
+ * must be terminated with '\0' on entry.
+ *
+ * Returns the length of the token found (not including the '\0').
+ * Return value will be 0 if no token is found, and it will be >=
+ * token_size if the token would not fit.
+ *
+ * The *buf pointer will be updated to point beyond the end of the
+ * found token.  Note that this occurs even if the token buffer is
+ * too small to hold it.
+ */
+static inline size_t copy_token(const char **buf,
+				char *token,
+				size_t token_size)
+{
+        size_t len;
+
+	len = next_token(buf);
+	if (len < token_size) {
+		memcpy(token, *buf, len);
+		*(token + len) = '\0';
+	}
+	*buf += len;
+
+        return len;
+}
+
+/*
+ * This fills in the pool_name, obj, obj_len, snap_name, obj_len,
+ * rbd_dev, rbd_md_name, and name fields of the given rbd_dev, based
+ * on the list of monitor addresses and other options provided via
+ * /sys/bus/rbd/add.
+ */
+static int rbd_add_parse_args(struct rbd_device *rbd_dev,
+			      const char *buf,
+			      const char **mon_addrs,
+			      size_t *mon_addrs_size,
+			      char *options,
+			      size_t options_size)
+{
+	size_t	len;
+
+	/* The first four tokens are required */
+
+	len = next_token(&buf);
+	if (!len)
+		return -EINVAL;
+	*mon_addrs_size = len + 1;
+	*mon_addrs = buf;
+
+	buf += len;
+
+	len = copy_token(&buf, options, options_size);
+	if (!len || len >= options_size)
+		return -EINVAL;
+
+	len = copy_token(&buf, rbd_dev->pool_name, sizeof (rbd_dev->pool_name));
+	if (!len || len >= sizeof (rbd_dev->pool_name))
+		return -EINVAL;
+
+	len = copy_token(&buf, rbd_dev->obj, sizeof (rbd_dev->obj));
+	if (!len || len >= sizeof (rbd_dev->obj))
+		return -EINVAL;
+
+	/* We have the object length in hand, save it. */
+
+	rbd_dev->obj_len = len;
+
+	BUILD_BUG_ON(RBD_MAX_MD_NAME_LEN
+				< RBD_MAX_OBJ_NAME_LEN + sizeof (RBD_SUFFIX));
+	sprintf(rbd_dev->obj_md_name, "%s%s", rbd_dev->obj, RBD_SUFFIX);
+
+	/*
+	 * The snapshot name is optional, but it's an error if it's
+	 * too long.  If no snapshot is supplied, fill in the default.
+	 */
+	len = copy_token(&buf, rbd_dev->snap_name, sizeof (rbd_dev->snap_name));
+	if (!len)
+		memcpy(rbd_dev->snap_name, RBD_SNAP_HEAD_NAME,
+			sizeof (RBD_SNAP_HEAD_NAME));
+	else if (len >= sizeof (rbd_dev->snap_name))
+		return -EINVAL;
+
+	return 0;
+}
+
+static ssize_t rbd_add(struct bus_type *bus,
+		       const char *buf,
+		       size_t count)
+{
+	struct rbd_device *rbd_dev;
+	const char *mon_addrs = NULL;
+	size_t mon_addrs_size = 0;
+	char *options = NULL;
+	struct ceph_osd_client *osdc;
+	int rc = -ENOMEM;
+
+	if (!try_module_get(THIS_MODULE))
+		return -ENODEV;
+
+	rbd_dev = kzalloc(sizeof(*rbd_dev), GFP_KERNEL);
+	if (!rbd_dev)
+		goto err_nomem;
+	options = kmalloc(count, GFP_KERNEL);
+	if (!options)
+		goto err_nomem;
+
+	/* static rbd_device initialization */
+	spin_lock_init(&rbd_dev->lock);
+	INIT_LIST_HEAD(&rbd_dev->node);
+	INIT_LIST_HEAD(&rbd_dev->snaps);
+	init_rwsem(&rbd_dev->header_rwsem);
+
+	init_rwsem(&rbd_dev->header_rwsem);
+
+	/* generate unique id: find highest unique id, add one */
+	rbd_id_get(rbd_dev);
+
+	/* Fill in the device name, now that we have its id. */
+	BUILD_BUG_ON(DEV_NAME_LEN
+			< sizeof (RBD_DRV_NAME) + MAX_INT_FORMAT_WIDTH);
+	sprintf(rbd_dev->name, "%s%d", RBD_DRV_NAME, rbd_dev->id);
+
+	/* parse add command */
+	rc = rbd_add_parse_args(rbd_dev, buf, &mon_addrs, &mon_addrs_size,
+				options, count);
+	if (rc)
+		goto err_put_id;
+
+	rbd_dev->rbd_client = rbd_get_client(mon_addrs, mon_addrs_size - 1,
+						options);
+	if (IS_ERR(rbd_dev->rbd_client)) {
+		rc = PTR_ERR(rbd_dev->rbd_client);
+		goto err_put_id;
+	}
+
+	/* pick the pool */
+	osdc = &rbd_dev->rbd_client->client->osdc;
+	rc = ceph_pg_poolid_by_name(osdc->osdmap, rbd_dev->pool_name);
+	if (rc < 0)
+		goto err_out_client;
+	rbd_dev->poolid = rc;
+
+	/* register our block device */
+	rc = register_blkdev(0, rbd_dev->name);
+	if (rc < 0)
+		goto err_out_client;
+	rbd_dev->major = rc;
+
+	rc = rbd_bus_add_dev(rbd_dev);
+	if (rc)
+		goto err_out_blkdev;
+
+	/*
+	 * At this point cleanup in the event of an error is the job
+	 * of the sysfs code (initiated by rbd_bus_del_dev()).
+	 *
+	 * Set up and announce blkdev mapping.
+	 */
+	rc = rbd_init_disk(rbd_dev);
+	if (rc)
+		goto err_out_bus;
+
+	rc = rbd_init_watch_dev(rbd_dev);
+	if (rc)
+		goto err_out_bus;
+
+	return count;
+
+err_out_bus:
+	/* this will also clean up rest of rbd_dev stuff */
+
+	rbd_bus_del_dev(rbd_dev);
+	kfree(options);
+	return rc;
+
+err_out_blkdev:
+	unregister_blkdev(rbd_dev->major, rbd_dev->name);
+err_out_client:
+	rbd_put_client(rbd_dev);
+err_put_id:
+	rbd_id_put(rbd_dev);
+err_nomem:
+	kfree(options);
+	kfree(rbd_dev);
+
+	dout("Error adding device %s\n", buf);
+	module_put(THIS_MODULE);
+
+	return (ssize_t) rc;
+}
+
+static struct rbd_device *__rbd_get_dev(unsigned long id)
+{
+	struct list_head *tmp;
+	struct rbd_device *rbd_dev;
+
+	spin_lock(&rbd_dev_list_lock);
+	list_for_each(tmp, &rbd_dev_list) {
+		rbd_dev = list_entry(tmp, struct rbd_device, node);
+		if (rbd_dev->id == id) {
+			spin_unlock(&rbd_dev_list_lock);
+			return rbd_dev;
+		}
+	}
+	spin_unlock(&rbd_dev_list_lock);
+	return NULL;
+}
+
+static void rbd_dev_release(struct device *dev)
+{
+	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+
+	if (rbd_dev->watch_request) {
+		struct ceph_client *client = rbd_dev->rbd_client->client;
+
+		ceph_osdc_unregister_linger_request(&client->osdc,
+						    rbd_dev->watch_request);
+	}
+	if (rbd_dev->watch_event)
+		rbd_req_sync_unwatch(rbd_dev, rbd_dev->obj_md_name);
+
+	rbd_put_client(rbd_dev);
+
+	/* clean up and free blkdev */
+	rbd_free_disk(rbd_dev);
+	unregister_blkdev(rbd_dev->major, rbd_dev->name);
+
+	/* done with the id, and with the rbd_dev */
+	rbd_id_put(rbd_dev);
+	kfree(rbd_dev);
+
+	/* release module ref */
+	module_put(THIS_MODULE);
+}
+
+static ssize_t rbd_remove(struct bus_type *bus,
+			  const char *buf,
+			  size_t count)
+{
+	struct rbd_device *rbd_dev = NULL;
+	int target_id, rc;
+	unsigned long ul;
+	int ret = count;
+
+	rc = strict_strtoul(buf, 10, &ul);
+	if (rc)
+		return rc;
+
+	/* convert to int; abort if we lost anything in the conversion */
+	target_id = (int) ul;
+	if (target_id != ul)
+		return -EINVAL;
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+
+	rbd_dev = __rbd_get_dev(target_id);
+	if (!rbd_dev) {
+		ret = -ENOENT;
+		goto done;
+	}
+
+	__rbd_remove_all_snaps(rbd_dev);
+	rbd_bus_del_dev(rbd_dev);
+
+done:
+	mutex_unlock(&ctl_mutex);
+	return ret;
+}
+
+static ssize_t rbd_snap_add(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf,
+			    size_t count)
+{
+	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
+	int ret;
+	char *name = kmalloc(count + 1, GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+
+	snprintf(name, count, "%s", buf);
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+
+	ret = rbd_header_add_snap(rbd_dev,
+				  name, GFP_KERNEL);
+	if (ret < 0)
+		goto err_unlock;
+
+	ret = __rbd_update_snaps(rbd_dev);
+	if (ret < 0)
+		goto err_unlock;
+
+	/* shouldn't hold ctl_mutex when notifying.. notify might
+	   trigger a watch callback that would need to get that mutex */
+	mutex_unlock(&ctl_mutex);
+
+	/* make a best effort, don't error if failed */
+	rbd_req_sync_notify(rbd_dev, rbd_dev->obj_md_name);
+
+	ret = count;
+	kfree(name);
+	return ret;
+
+err_unlock:
+	mutex_unlock(&ctl_mutex);
+	kfree(name);
+	return ret;
+}
+
+/*
+ * create control files in sysfs
+ * /sys/bus/rbd/...
+ */
+static int rbd_sysfs_init(void)
+{
+	int ret;
+
+	ret = device_register(&rbd_root_dev);
+	if (ret < 0)
+		return ret;
+
+	ret = bus_register(&rbd_bus_type);
+	if (ret < 0)
+		device_unregister(&rbd_root_dev);
+
+	return ret;
+}
+
+static void rbd_sysfs_cleanup(void)
+{
+	bus_unregister(&rbd_bus_type);
+	device_unregister(&rbd_root_dev);
+}
+
+int __init rbd_init(void)
+{
+	int rc;
+
+	rc = rbd_sysfs_init();
+	if (rc)
+		return rc;
+	pr_info("loaded " RBD_DRV_NAME_LONG "\n");
+	return 0;
+}
+
+void __exit rbd_exit(void)
+{
+	rbd_sysfs_cleanup();
+}
+
+module_init(rbd_init);
+module_exit(rbd_exit);
+
+MODULE_AUTHOR("Sage Weil <sage@newdream.net>");
+MODULE_AUTHOR("Yehuda Sadeh <yehuda@hq.newdream.net>");
+MODULE_DESCRIPTION("rados block device");
+
+/* following authorship retained from original osdblk.c */
+MODULE_AUTHOR("Jeff Garzik <jeff@garzik.org>");
+
+MODULE_LICENSE("GPL");