Date:	Wed, 1 Apr 2009 21:54:55 -0400
From:	Jeff Garzik <jeff@...zik.org>
To:	LKML <linux-kernel@...r.kernel.org>, linux-scsi@...r.kernel.org
Cc:	linux-fsdevel@...r.kernel.org, axboe@...nel.dk,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] osdblk: a Linux block device for OSD objects


As I promised in older exofs threads, here is a client for libosd
_other_ than exofs.  This block driver exports a single OSD object
as a Linux block device.

See the comment block at the top of the driver for usage instructions.



 drivers/block/Kconfig  |   16 +
 drivers/block/Makefile |    1 
 drivers/block/osdblk.c |  563 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 580 insertions(+)

diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index e7b8aa0..ff46b0e 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -298,6 +298,22 @@ config BLK_DEV_NBD
 
 	  If unsure, say N.
 
+config BLK_DEV_OSD
+	tristate "OSD object-as-blkdev support"
+	depends on SCSI_OSD_INITIATOR
+	---help---
+	  Saying Y or M here will allow the exporting of a single SCSI
+	  OSD (object-based storage) object as a Linux block device.
+
+	  For example, if you create a 2G object on an OSD device,
+	  you can then use this module to present that 2G object as
+	  a Linux block device.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called osdblk.
+
+	  If unsure, say N.
+
 config BLK_DEV_SX8
 	tristate "Promise SATA SX8 support"
 	depends on PCI
diff --git a/drivers/block/Makefile b/drivers/block/Makefile
index 3145141..859bf5d 100644
--- a/drivers/block/Makefile
+++ b/drivers/block/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_BLK_DEV_DAC960)	+= DAC960.o
 obj-$(CONFIG_XILINX_SYSACE)	+= xsysace.o
 obj-$(CONFIG_CDROM_PKTCDVD)	+= pktcdvd.o
 obj-$(CONFIG_SUNVDC)		+= sunvdc.o
+obj-$(CONFIG_BLK_DEV_OSD)	+= osdblk.o
 
 obj-$(CONFIG_BLK_DEV_UMEM)	+= umem.o
 obj-$(CONFIG_BLK_DEV_NBD)	+= nbd.o
diff --git a/drivers/block/osdblk.c b/drivers/block/osdblk.c
new file mode 100644
index 0000000..d3a2fb5
--- /dev/null
+++ b/drivers/block/osdblk.c
@@ -0,0 +1,563 @@
+
+/*
+   osdblk.c -- Export a single SCSI OSD object as a Linux block device
+
+
+   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.
+
+
+   Instructions for use
+   --------------------
+
+   1) Map a Linux block device to an existing OSD object.
+
+      In this example, we will use partition id 1234, object id 5678,
+      OSD device /dev/osd1.
+
+      $ echo "1234 5678 /dev/osd1" > /sys/class/osdblk/add
+
+
+   2) List all active blkdev<->object mappings.
+
+      In this example, we have performed step #1 twice, creating two blkdevs,
+      mapped to two separate OSD objects.
+
+      $ cat /sys/class/osdblk/list
+      0 174 1234 5678 /dev/osd1
+      1 179 1994 897123 /dev/osd0
+
+      The columns, in order, are:
+      - blkdev unique id
+      - blkdev assigned major
+      - OSD object partition id
+      - OSD object id
+      - OSD device
+
+
+   3) Remove an active blkdev<->object mapping.
+
+      $ echo 1 > /sys/class/osdblk/remove
+
+
+   NOTE:  The actual creation and deletion of OSD objects is outside the scope
+   of this driver.
+
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <scsi/osd_initiator.h>
+#include <scsi/osd_attributes.h>
+#include <scsi/osd_sec.h>
+
+#define DRV_NAME "osdblk"
+#define PFX DRV_NAME ": "
+
+struct osdblk_device;
+
+enum {
+	OSDBLK_MAX_DEVS		= 64,
+	OSDBLK_MINORS_PER_MAJOR	= 256,
+	OSDBLK_MAX_REQ		= 32,
+	OSDBLK_OP_TIMEOUT	= 4 * 60,
+};
+
+struct osdblk_request {
+	struct request		*rq;
+	struct bio		*bio;
+	struct osdblk_device	*osdev;
+	int			tag;
+	uint8_t			cred[OSD_CAP_LEN];
+};
+
+struct osdblk_device {
+	int			id;
+
+	int			major;
+	struct gendisk		*disk;
+	struct request_queue	*q;
+
+	struct osd_dev		*osd;
+
+	char			name[32];
+
+	spinlock_t		lock;
+
+	struct osd_obj_id	obj;
+	uint8_t			obj_cred[OSD_CAP_LEN];
+
+	struct osdblk_request	req[OSDBLK_MAX_REQ];
+
+	unsigned long		part_id;
+	unsigned long		obj_id;
+	char			osd_path[0];
+};
+
+static struct class *class_osdblk;		/* /sys/class/osdblk */
+static struct mutex ctl_mutex;	/* Serialize open/close/setup/teardown */
+static struct osdblk_device *osdblk_devs[OSDBLK_MAX_DEVS];
+
+static struct block_device_operations osdblk_bd_ops = {
+	.owner		= THIS_MODULE,
+};
+
+const struct osd_attr g_attr_logical_length = ATTR_DEF(
+	OSD_APAGE_OBJECT_INFORMATION, OSD_ATTR_OI_LOGICAL_LENGTH, 8);
+
+static void osd_make_credential(u8 cred_a[OSD_CAP_LEN],
+				const struct osd_obj_id *obj)
+{
+	osd_sec_init_nosec_doall_caps(cred_a, obj, false, true);
+}
+
+/*
+ * Perform a synchronous OSD operation.
+ */
+static int osd_sync_op(struct osd_request *or, int timeout, uint8_t *credential)
+{
+	int ret;
+
+	or->timeout = timeout;
+	ret = osd_finalize_request(or, 0, credential, NULL);
+	if (ret)
+		return ret;
+
+	ret = osd_execute_request(or);
+
+	/* osd_req_decode_sense(or, ret); */
+	return ret;
+}
+
+/*
+ * Perform an asynchronous OSD operation.
+ */
+static int osd_async_op(struct osd_request *or, osd_req_done_fn *async_done,
+		   void *caller_context, u8 *cred)
+{
+	int ret;
+
+	ret = osd_finalize_request(or, 0, cred, NULL);
+	if (ret)
+		return ret;
+
+	ret = osd_execute_request_async(or, async_done, caller_context);
+
+	return ret;
+}
+
+static int extract_attr_from_req(struct osd_request *or, 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(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 osdblk_get_obj_size(struct osdblk_device *osdev, u64 *size_out)
+{
+	struct osd_request *or;
+	struct osd_attr attr;
+	int ret;
+
+	osd_make_credential(osdev->obj_cred, &osdev->obj);
+
+	or = osd_start_request(osdev->osd, GFP_KERNEL);
+	if (!or)
+		return -ENOMEM;
+
+	osd_req_get_attributes(or, &osdev->obj);
+
+	osd_req_add_get_attr_list(or, &g_attr_logical_length, 1);
+
+	/* execute op synchronously */
+	ret = osd_sync_op(or, OSDBLK_OP_TIMEOUT, osdev->obj_cred);
+	if (ret)
+		goto out;
+
+	attr = g_attr_logical_length;
+	ret = extract_attr_from_req(or, &attr);
+	if (ret)
+		goto out;
+
+	*size_out = get_unaligned_be64(attr.val_ptr);
+
+out:
+	osd_end_request(or);
+	return ret;
+
+}
+
+static int osdblk_get_free_req(struct osdblk_device *osdev)
+{
+	int i;
+
+	for (i = 0; i < OSDBLK_MAX_REQ; i++) {
+		if (!osdev->req[i].rq)
+			return i;
+	}
+
+	return -1;
+}
+
+static void osdblk_end_request(struct osdblk_device *osdev,
+			       struct osdblk_request *orq,
+			       int error)
+{
+	struct request *rq = orq->rq;
+	int rc;
+
+	/* complete request, at block layer */
+	rc = __blk_end_request(rq, error, blk_rq_bytes(rq));
+
+	/* clear request slot for use */
+	osdev->req[orq->tag].rq = NULL;
+
+	/* restart queue, if necessary */
+	blk_start_queue(osdev->q);
+}
+
+static void osdblk_osd_complete(struct osd_request *or, void *private)
+{
+	struct osdblk_request *orq = private;
+	struct osd_sense_info osi;
+	int ret = osd_req_decode_sense(or, &osi);
+
+	if (ret)
+		ret = -EIO;
+
+	osd_end_request(or);
+	osdblk_end_request(orq->osdev, orq, ret);
+}
+
+static void osdblk_rq_fn(struct request_queue *q)
+{
+	struct osdblk_device *osdev = q->queuedata;
+	struct request *rq;
+	struct osdblk_request *orq;
+	struct osd_request *or;
+	struct bio *bio;
+	int rq_idx, do_write;
+
+	while (1) {
+		rq = elv_next_request(q);
+		if (!rq)
+			break;
+
+		do_write = (rq_data_dir(rq) == WRITE);
+
+		bio = bio_clone(rq->bio, GFP_NOIO);
+		if (!bio)
+			break;
+
+		rq_idx = osdblk_get_free_req(osdev);
+		if (rq_idx < 0) {
+			bio_put(bio);
+			blk_stop_queue(q);
+			break;
+		}
+
+		orq = &osdev->req[rq_idx];
+		orq->tag = rq_idx;
+		orq->rq = rq;
+		orq->bio = bio;
+		orq->osdev = osdev;
+
+		blkdev_dequeue_request(rq);
+
+		osd_make_credential(orq->cred, &osdev->obj);
+
+		or = osd_start_request(osdev->osd, GFP_NOIO);
+		if (!or) {
+			blk_requeue_request(q, rq);
+			bio_put(bio);
+			break;
+		}
+
+		if (do_write)
+			osd_req_write(or, &osdev->obj, bio,
+				      rq->sector * 512ULL);
+		else
+			osd_req_read(or, &osdev->obj, bio,
+				     rq->sector * 512ULL);
+
+		if (osd_async_op(or, osdblk_osd_complete, orq, orq->cred)) {
+			/* FIXME: leak OSD request 'or' ? */
+			blk_requeue_request(q, rq);
+			bio_put(bio);
+		}
+	}
+}
+
+static void osdblk_free_disk(struct osdblk_device *osdev)
+{
+	struct gendisk *disk = osdev->disk;
+
+	if (!disk)
+		return;
+
+	if (disk->flags & GENHD_FL_UP)
+		del_gendisk(disk);
+	if (disk->queue)
+		blk_cleanup_queue(disk->queue);
+	put_disk(disk);
+}
+
+static int osdblk_init_disk(struct osdblk_device *osdev)
+{
+	struct gendisk *disk;
+	struct request_queue *q;
+	int rc;
+	u64 obj_size = 0;
+
+	rc = osdblk_get_obj_size(osdev, &obj_size);
+	if (rc)
+		return rc;
+
+	disk = alloc_disk(OSDBLK_MINORS_PER_MAJOR);
+	if (!disk)
+		return -ENOMEM;
+
+	sprintf(disk->disk_name, DRV_NAME "/%d", osdev->id);
+	disk->major = osdev->major;
+	disk->first_minor = 0;
+	disk->fops = &osdblk_bd_ops;
+	disk->private_data = osdev;
+
+	q = blk_init_queue(osdblk_rq_fn, &osdev->lock);
+	if (!q) {
+		put_disk(disk);
+		return -ENOMEM;
+	}
+
+	disk->queue = q;
+
+	q->queuedata = osdev;
+
+	osdev->disk = disk;
+	osdev->q = q;
+
+	set_capacity(disk, obj_size);
+	add_disk(disk);
+
+	return 0;
+}
+
+/********************************************************************
+  /sys/class/osdblk/
+                     add	map OSD object to blkdev
+                     remove	unmap OSD object
+                     list	show mappings
+ *******************************************************************/
+
+static void class_osdblk_release(struct class *cls)
+{
+	kfree(cls);
+}
+
+static ssize_t class_osdblk_show(struct class *c, char *data)
+{
+	int n = 0;
+	int idx;
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+	for (idx = 0; idx < OSDBLK_MAX_DEVS; idx++) {
+		struct osdblk_device *osdev = osdblk_devs[idx];
+		if (!osdev)
+			continue;
+		n += sprintf(data+n, "%d %d %lu %lu %s\n",
+			osdev->id,
+			osdev->major,
+			osdev->part_id,
+			osdev->obj_id,
+			osdev->osd_path);
+	}
+	mutex_unlock(&ctl_mutex);
+	return n;
+}
+
+static ssize_t class_osdblk_add(struct class *c, const char *buf, size_t count)
+{
+	struct osdblk_device *osdev;
+	ssize_t rc;
+	int idx, irc;
+
+	osdev = kzalloc(sizeof(*osdev) + strlen(buf) + 1, GFP_KERNEL);
+	if (!osdev)
+		return -ENOMEM;
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+
+	for (idx = 0; idx < OSDBLK_MAX_DEVS; idx++) {
+		if (!osdblk_devs[idx]) {
+			osdblk_devs[idx] = osdev;
+			osdev->id = idx;
+			break;
+		}
+	}
+
+	mutex_unlock(&ctl_mutex);
+
+	if (idx == OSDBLK_MAX_DEVS) {
+		rc = -ENOSPC;
+		goto err_out;
+	}
+
+	if (sscanf(buf, "%lu %lu %s", &osdev->part_id, &osdev->obj_id,
+		   osdev->osd_path) != 3) {
+		rc = -EINVAL;
+		goto err_out_slot;
+	}
+
+	osdev->obj.partition = osdev->part_id;
+	osdev->obj.id = osdev->obj_id;
+
+	sprintf(osdev->name, DRV_NAME "%d", osdev->id);
+	spin_lock_init(&osdev->lock);
+
+	osdev->osd = osduld_path_lookup(osdev->osd_path);
+	if (IS_ERR(osdev->osd)) {
+		rc = PTR_ERR(osdev->osd);
+		goto err_out_slot;
+	}
+
+	irc = register_blkdev(0, osdev->name);
+	if (irc < 0) {
+		rc = irc;
+		goto err_out_osd;
+	}
+
+	osdev->major = irc;
+
+	rc = osdblk_init_disk(osdev);
+	if (rc)
+		goto err_out_blkdev;
+
+	return 0;
+
+err_out_blkdev:
+	unregister_blkdev(osdev->major, osdev->name);
+err_out_osd:
+	osduld_put_device(osdev->osd);
+err_out_slot:
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+	osdblk_devs[osdev->id] = NULL;
+	mutex_unlock(&ctl_mutex);
+err_out:
+	kfree(osdev);
+	return rc;
+}
+
+static ssize_t class_osdblk_remove(struct class *c, const char *buf,
+					size_t count)
+{
+	struct osdblk_device *osdev;
+	int target_id;
+
+	if (sscanf(buf, "%d", &target_id) != 1)
+		return -EINVAL;
+	if (target_id < 0 || target_id >= OSDBLK_MAX_DEVS)
+		return -EINVAL;
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+	osdev = osdblk_devs[target_id];
+	osdblk_devs[target_id] = NULL;
+	mutex_unlock(&ctl_mutex);
+
+	if (!osdev)
+		return -ENOENT;
+
+	osdblk_free_disk(osdev);
+	unregister_blkdev(osdev->major, osdev->name);
+	osduld_put_device(osdev->osd);
+	kfree(osdev);
+
+	return 0;
+}
+
+static struct class_attribute class_osdblk_attrs[] = {
+	__ATTR(add,	0200, NULL, class_osdblk_add),
+	__ATTR(remove,	0200, NULL, class_osdblk_remove),
+	__ATTR(list,	0444, class_osdblk_show, NULL),
+	__ATTR_NULL
+};
+
+static int osdblk_sysfs_init(void)
+{
+	int ret = 0;
+
+	/*
+	 * create control files in sysfs
+	 * /sys/class/osdblk/...
+	 */
+	class_osdblk = kzalloc(sizeof(*class_osdblk), GFP_KERNEL);
+	if (!class_osdblk)
+		return -ENOMEM;
+
+	class_osdblk->name = DRV_NAME;
+	class_osdblk->owner = THIS_MODULE;
+	class_osdblk->class_release = class_osdblk_release;
+	class_osdblk->class_attrs = class_osdblk_attrs;
+
+	ret = class_register(class_osdblk);
+	if (ret) {
+		kfree(class_osdblk);
+		class_osdblk = NULL;
+		printk(PFX "failed to create class osdblk\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static void osdblk_sysfs_cleanup(void)
+{
+	if (class_osdblk)
+		class_destroy(class_osdblk);
+	class_osdblk = NULL;
+}
+
+static int __init osdblk_init(void)
+{
+	int rc;
+
+	rc = osdblk_sysfs_init();
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+static void __exit osdblk_exit(void)
+{
+	osdblk_sysfs_cleanup();
+}
+
+module_init(osdblk_init);
+module_exit(osdblk_exit);
+
--
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