Here is my latest dm-userspace kernel code. This has a lot of
cleanups and fixes since the last version. We have been successfully
using this version for a while and believe it to be quite stable and
well-performing. It is not intended to be in final form, but I think
it should be close to functionally complete.
I will post the updated userspace code shortly.
--
Dan Smith
IBM Linux Technology Center
Open Hypervisor Team
email: danms@xxxxxxxxxx
Signed-off-by: Dan Smith <danms@xxxxxxxxxx>
diff -Naur linux-2.6.18-orig/drivers/md/dm-user.h linux-2.6.18-dmu/drivers/md/dm-user.h
--- linux-2.6.18-orig/drivers/md/dm-user.h 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.18-dmu/drivers/md/dm-user.h 2006-09-28 13:49:18.000000000 -0700
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) International Business Machines Corp., 2006
+ * Author: Dan Smith <danms@xxxxxxxxxx>
+ *
+ * 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; under version 2 of the License.
+ *
+ * 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; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#ifndef __DM_USER_H
+#define __DM_USER_H
+
+#include <linux/hardirq.h>
+
+#define DMU_KEY_LEN 256
+
+extern struct target_type userspace_target;
+extern mempool_t *request_pool;
+extern dev_t dmu_dev;
+extern spinlock_t devices_lock;
+extern struct list_head devices;
+
+#define DMU_CP_HASH 1024
+
+/*
+ * A block device that we can send bios to
+ */
+struct target_device {
+ struct list_head list; /* Our place in the targets list */
+ struct block_device *bdev; /* The target block_device */
+ struct kref users; /* Self-destructing reference count */
+};
+
+/*
+ * A dm-userspace device, which consists of multiple targets sharing a
+ * common key
+ */
+struct dmu_device {
+ struct list_head list; /* Our place in the devices list */
+
+ spinlock_t lock; /* Protects all the fields below */
+
+ /* We need to protect the TX list with a separate lock that is
+ * always used with IRQs disabled because it is locked from
+ * inside the endio function
+ */
+ spinlock_t tx_lock;
+ struct list_head tx_requests; /* Requests to send to userspace */
+
+ struct list_head rx_requests; /* Requests waiting for reply */
+
+ struct semaphore cp_sem; /* Protection for cp_requests */
+ struct list_head cp_requests; /* Requests waiting to be copied */
+
+ /* Accounting */
+ atomic_t t_reqs; /* Waiting to be sent to userspace */
+ atomic_t r_reqs; /* Waiting for a response from uspace*/
+ atomic_t f_reqs; /* Submitted, waiting for endio */
+ atomic_t total; /* Total requests allocated */
+
+ atomic_t idcounter; /* Counter for making request IDs */
+
+ struct list_head target_devs; /* List of devices we can target */
+
+ void *transport_private; /* Private data for userspace comms */
+
+ char key[DMU_KEY_LEN]; /* Unique name string for device */
+ struct kref users; /* Self-destructing reference count */
+
+ wait_queue_head_t wqueue; /* To block while waiting for reqs */
+ wait_queue_head_t lowmem; /* To block while waiting for memory */
+
+ uint64_t block_size; /* Block size for this device */
+ uint64_t block_mask; /* Mask for offset in block */
+ unsigned int block_shift; /* Shift to convert to/from block */
+
+ struct kcopyd_client *kcopy; /* Interface to kcopyd */
+};
+
+struct dmu_request {
+ struct list_head list; /* Our place on the request queue */
+ struct list_head copy; /* Our place on the copy list */
+ struct dmu_device *dev; /* The DMU device that owns us */
+
+ int type; /* Type of request */
+ uint32_t flags; /* Attribute flags */
+ uint64_t id; /* Unique ID for sync with userspace */
+ union {
+ uint64_t block; /* The block in question */
+ } u;
+
+ struct list_head deps; /* Requests depending on this one */
+ struct bio *bio; /* The bio this request represents */
+
+ struct work_struct task; /* Async task to run for this req */
+
+ struct dmu_msg_map_response response; /* FIXME: Clean this up */
+};
+
+
+/* Find and grab a reference to a target device */
+struct target_device *find_target(struct dmu_device *dev,
+ dev_t devno);
+/* Character device transport functions */
+int register_chardev_transport(struct dmu_device *dev);
+void unregister_chardev_transport(struct dmu_device *dev);
+int init_chardev_transport(void);
+void cleanup_chardev_transport(void);
+void write_chardev_transport_info(struct dmu_device *dev,
+ char *buf, unsigned int maxlen);
+
+/* Return the block number for @sector */
+static inline u64 dmu_block(struct dmu_device *dev,
+ sector_t sector)
+{
+ return sector >> dev->block_shift;
+}
+
+/* Return the sector offset in a block for @sector */
+static inline u64 dmu_sector_offset(struct dmu_device *dev,
+ sector_t sector)
+{
+ return sector & dev->block_mask;
+}
+
+/* Return the starting sector for @block */
+static inline u64 dmu_sector(struct dmu_device *dev,
+ uint64_t block)
+{
+ return block << dev->block_shift;
+}
+
+/* Increase the usage count for @dev */
+static inline void get_dev(struct dmu_device *dev)
+{
+ kref_get(&dev->users);
+}
+
+/* Decrease the usage count for @dev */
+void destroy_dmu_device(struct kref *ref);
+static inline void put_dev(struct dmu_device *dev)
+{
+ kref_put(&dev->users, destroy_dmu_device);
+}
+
+#endif
diff -Naur linux-2.6.18-orig/drivers/md/dm-userspace.c linux-2.6.18-dmu/drivers/md/dm-userspace.c
--- linux-2.6.18-orig/drivers/md/dm-userspace.c 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.18-dmu/drivers/md/dm-userspace.c 2006-09-28 13:49:18.000000000 -0700
@@ -0,0 +1,585 @@
+/*
+ * Copyright (C) International Business Machines Corp., 2006
+ * Author: Dan Smith <danms@xxxxxxxxxx>
+ *
+ * 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; under version 2 of the License.
+ *
+ * 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; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/types.h>
+#include <linux/poll.h>
+
+#include <linux/dm-userspace.h>
+
+#include "dm.h"
+#include "dm-bio-list.h"
+#include "kcopyd.h"
+#include "dm-user.h"
+
+#define DMU_COPY_PAGES 256
+
+#define DM_MSG_PREFIX "dm-userspace"
+
+static kmem_cache_t *request_cache;
+mempool_t *request_pool;
+
+spinlock_t devices_lock;
+LIST_HEAD(devices);
+
+/* Device number for the control device */
+dev_t dmu_dev;
+
+/* Add a request to a device's request queue */
+static void add_tx_request(struct dmu_device *dev,
+ struct dmu_request *req)
+{
+ unsigned long flags;
+
+ BUG_ON(!list_empty(&req->list));
+
+ spin_lock_irqsave(&dev->tx_lock, flags);
+ list_add_tail(&req->list, &dev->tx_requests);
+ atomic_inc(&dev->t_reqs);
+ spin_unlock_irqrestore(&dev->tx_lock, flags);
+
+ wake_up(&dev->wqueue);
+}
+
+static void endio_worker(void *data)
+{
+ struct dmu_request *req = data;
+ struct dmu_device *dev = req->dev;
+
+ spin_lock(&dev->lock);
+ if (list_empty(&req->list) && list_empty(&req->copy)) {
+ mempool_free(req, request_pool);
+ atomic_dec(&dev->f_reqs);
+ atomic_dec(&dev->total);
+ wake_up_interruptible(&dev->lowmem);
+ } else {
+ PREPARE_WORK(&req->task, endio_worker, req);
+ schedule_work(&req->task);
+ }
+ spin_unlock(&dev->lock);
+}
+
+/* Return an already-bound target device */
+struct target_device *find_target(struct dmu_device *dev,
+ dev_t devno)
+{
+ struct target_device *target, *match = NULL;
+
+ spin_lock(&dev->lock);
+ list_for_each_entry(target, &dev->target_devs, list) {
+ if (target->bdev->bd_dev == devno) {
+ match = target;
+ break;
+ }
+ }
+ spin_unlock(&dev->lock);
+
+ return match;
+}
+
+/* Find a new target device and bind it to our device */
+static struct target_device *get_target(struct dmu_device *dev,
+ dev_t devno)
+{
+ struct target_device *target;
+ struct block_device *bdev;
+
+ target = find_target(dev, devno);
+ if (target)
+ return target;
+
+ bdev = open_by_devnum(devno, FMODE_READ | FMODE_WRITE);
+ if (IS_ERR(bdev)) {
+ DMERR("Unable to lookup device %x", devno);
+ return NULL;
+ }
+
+ target = kmalloc(sizeof(*target), GFP_KERNEL);
+ if (!target) {
+ DMERR("Unable to alloc new target device");
+ return NULL;
+ }
+
+ target->bdev = bdev;
+ INIT_LIST_HEAD(&target->list);
+
+ if (in_interrupt())
+ printk("%s in irq\n", __FUNCTION__);
+
+ spin_lock(&dev->lock);
+ list_add_tail(&target->list, &dev->target_devs);
+ spin_unlock(&dev->lock);
+
+ return target;
+}
+
+/* Caller must hold dev->lock */
+static void put_target(struct dmu_device *dev,
+ struct target_device *target)
+{
+ list_del(&target->list);
+
+ bd_release(target->bdev);
+ blkdev_put(target->bdev);
+
+ kfree(target);
+}
+
+void destroy_dmu_device(struct kref *ref)
+{
+ struct dmu_device *dev;
+ struct list_head *cursor, *next;
+
+ dev = container_of(ref, struct dmu_device, users);
+
+ spin_lock(&devices_lock);
+ list_del(&dev->list);
+ spin_unlock(&devices_lock);
+
+ list_for_each_safe(cursor, next, &dev->target_devs) {
+ struct target_device *target;
+
+ target = list_entry(cursor,
+ struct target_device,
+ list);
+
+ put_target(dev, target);
+ }
+
+ list_for_each_safe(cursor, next, &dev->tx_requests) {
+ struct dmu_request *req;
+
+ req = list_entry(cursor,
+ struct dmu_request,
+ list);
+
+ DMERR("Failing unsent bio");
+ bio_io_error(req->bio, req->bio->bi_size);
+
+ list_del(&req->list);
+
+ mempool_free(req, request_pool);
+ }
+
+ list_for_each_safe(cursor, next, &dev->rx_requests) {
+ struct dmu_request *req;
+
+ req = list_entry(cursor,
+ struct dmu_request,
+ list);
+
+ DMERR("Failing bio");
+ req->flags = 0;
+ bio_io_error(req->bio, req->bio->bi_size);
+
+ list_del(&req->list);
+
+ mempool_free(req, request_pool);
+ }
+
+ list_for_each_safe(cursor, next, &dev->cp_requests) {
+ struct dmu_request *req;
+
+ req = list_entry(cursor,
+ struct dmu_request,
+ list);
+
+ DMERR("Failing bio");
+ req->flags = 0;
+ bio_io_error(req->bio, req->bio->bi_size);
+
+ list_del(&req->list);
+
+ mempool_free(req, request_pool);
+ }
+
+ kcopyd_client_destroy(dev->kcopy);
+ unregister_chardev_transport(dev);
+
+ kfree(dev);
+}
+
+static int init_dmu_device(struct dmu_device *dev, u32 block_size)
+{
+ int ret;
+
+ init_waitqueue_head(&dev->wqueue);
+ init_waitqueue_head(&dev->lowmem);
+ INIT_LIST_HEAD(&dev->list);
+ INIT_LIST_HEAD(&dev->target_devs);
+ kref_init(&dev->users);
+ spin_lock_init(&dev->lock);
+ spin_lock_init(&dev->tx_lock);
+
+ INIT_LIST_HEAD(&dev->tx_requests);
+ INIT_LIST_HEAD(&dev->rx_requests);
+ INIT_LIST_HEAD(&dev->cp_requests);
+
+ dev->block_size = block_size;
+ dev->block_mask = block_size - 1;
+ dev->block_shift = ffs(block_size) - 1;
+
+ atomic_set(&dev->t_reqs, 0);
+ atomic_set(&dev->r_reqs, 0);
+ atomic_set(&dev->f_reqs, 0);
+ atomic_set(&dev->total, 0);
+ atomic_set(&dev->idcounter, 0);
+
+ init_MUTEX(&dev->cp_sem);
+
+ ret = kcopyd_client_create(DMU_COPY_PAGES, &dev->kcopy);
+ if (ret) {
+ DMERR("Failed to initialize kcopyd client");
+ return 0;
+ }
+
+ return 1;
+}
+
+static struct dmu_device *new_dmu_device(char *key,
+ struct dm_target *ti,
+ u32 block_size)
+{
+ struct dmu_device *dev;
+ int ret;
+
+ dev = kmalloc(sizeof(*dev), GFP_KERNEL);
+ if (dev == NULL) {
+ DMERR("Failed to allocate new userspace device");
+ return NULL;
+ }
+
+ if (!init_dmu_device(dev, block_size))
+ goto bad1;
+
+ snprintf(dev->key, DMU_KEY_LEN, "%s", key);
+
+ ret = register_chardev_transport(dev);
+ if (!ret)
+ goto bad2;
+
+ spin_lock(&devices_lock);
+ list_add(&dev->list, &devices);
+ spin_unlock(&devices_lock);
+
+ return dev;
+
+ bad2:
+ put_dev(dev);
+ bad1:
+ kfree(dev);
+ DMERR("Failed to create device");
+ return NULL;
+}
+
+static struct dmu_device *find_dmu_device(const char *key)
+{
+ struct dmu_device *dev;
+ struct dmu_device *match = NULL;
+
+ spin_lock(&devices_lock);
+
+ list_for_each_entry(dev, &devices, list) {
+ spin_lock(&dev->lock);
+ if (strncmp(dev->key, key, DMU_KEY_LEN) == 0) {
+ match = dev;
+ spin_unlock(&dev->lock);
+ break;
+ }
+ spin_unlock(&dev->lock);
+ }
+
+ spin_unlock(&devices_lock);
+
+ return match;
+}
+
+static int dmu_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+ uint64_t block_size;
+ struct dmu_device *dev;
+ char *device_key;
+ char *block_size_param;
+ int target_idx = 2;
+
+ if (argc < 3) {
+ ti->error = "Invalid argument count";
+ return -EINVAL;
+ }
+
+ device_key = argv[0];
+ block_size_param = argv[1];
+
+ block_size = simple_strtoul(block_size_param, NULL, 10) / 512;
+
+ dev = find_dmu_device(device_key);
+ if (dev == NULL) {
+ dev = new_dmu_device(device_key,
+ ti,
+ block_size);
+ if (dev == NULL) {
+ ti->error = "Failed to create device";
+ goto bad;
+ }
+ } else {
+ get_dev(dev);
+ }
+
+ spin_lock(&dev->lock);
+ if (dev->block_size != block_size) {
+ ti->error = "Invalid block size";
+ goto bad;
+ }
+ spin_unlock(&dev->lock);
+
+ /* Resolve target devices */
+ do {
+ int maj, min;
+ sscanf(argv[target_idx], "%i:%i", &maj, &min);
+ if (!get_target(dev, MKDEV(maj, min))) {
+ DMERR("Failed to find target device %i:%i (%s)",
+ maj, min, argv[target_idx]);
+ goto out;
+ }
+ } while (++target_idx < argc);
+
+ ti->private = dev;
+ ti->split_io = block_size;
+
+ return 0;
+
+ bad:
+ if (dev) {
+ spin_unlock(&dev->lock);
+ }
+ out:
+ if (dev) {
+ put_dev(dev);
+ }
+
+ return -EINVAL;
+}
+
+static void dmu_dtr(struct dm_target *ti)
+{
+ struct dmu_device *dev = (struct dmu_device *) ti->private;
+
+ put_dev(dev);
+}
+
+static void init_req(struct dmu_device *dev,
+ struct bio *bio,
+ struct dmu_request *req)
+{
+ req->id = (uint64_t) atomic_add_return(1, &dev->idcounter);
+
+ req->type = DM_USERSPACE_MAP_BLOCK_REQ;
+ req->dev = dev;
+ req->bio = bio;
+ req->u.block = dmu_block(dev, bio->bi_sector);
+ req->flags = 0;
+ INIT_LIST_HEAD(&req->deps);
+ INIT_LIST_HEAD(&req->list);
+ INIT_LIST_HEAD(&req->copy);
+
+ if (bio_rw(bio))
+ dmu_set_flag(&req->flags, DMU_FLAG_WR);
+}
+
+static int dmu_map(struct dm_target *ti, struct bio *bio,
+ union map_info *map_context)
+{
+ struct dmu_device *dev = (struct dmu_device *) ti->private;
+ struct dmu_request *req;
+
+ if (unlikely(bio_barrier(bio))) {
+ printk("Refusing bio barrier\n");
+ return -EOPNOTSUPP;
+ }
+
+ wait_event_interruptible(dev->lowmem,
+ atomic_read(&dev->total) <= 20000);
+
+ req = mempool_alloc(request_pool, GFP_NOIO);
+ if (!req) {
+ DMERR("Failed to alloc request");
+ return -1;
+ }
+
+ atomic_inc(&dev->total);
+
+ map_context->ptr = req;
+
+ init_req(dev, bio, req);
+
+ add_tx_request(dev, req);
+
+ return 0;
+}
+
+static int dmu_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned int maxlen)
+{
+ struct dmu_device *dev = (struct dmu_device *) ti->private;
+
+ /* FIXME: Remove after debug */
+ spin_lock(&dev->lock);
+ printk("Requests: %u t:%u r:%u f:%u (%c%c%c)\n",
+ atomic_read(&dev->total),
+ atomic_read(&dev->t_reqs),
+ atomic_read(&dev->r_reqs),
+ atomic_read(&dev->f_reqs),
+ list_empty(&dev->tx_requests) ? ' ':'T',
+ list_empty(&dev->rx_requests) ? ' ':'R',
+ list_empty(&dev->cp_requests) ? ' ':'C');
+ spin_unlock(&dev->lock);
+
+
+ switch (type) {
+ case STATUSTYPE_INFO:
+ write_chardev_transport_info(dev, result, maxlen);
+ break;
+
+ case STATUSTYPE_TABLE:
+ snprintf(result, maxlen, "%s %llu",
+ dev->key,
+ dev->block_size * 512);
+ break;
+ }
+
+ return 0;
+}
+
+static int dmu_end_io(struct dm_target *ti, struct bio *bio,
+ int error, union map_info *map_context)
+{
+ struct dmu_request *req = map_context->ptr;
+ int ret = 0;
+
+ if (error)
+ return -1;
+
+ if (dmu_get_flag(&req->flags, DMU_FLAG_SYNC)) {
+ req->type = DM_USERSPACE_MAP_DONE;
+ add_tx_request(req->dev, req);
+ ret = 1;
+ } else {
+ INIT_WORK(&req->task, endio_worker, req);
+ schedule_work(&req->task);
+ }
+
+ return ret;
+}
+
+struct target_type userspace_target = {
+ .name = "userspace",
+ .version = {0, 1, 0},
+ .module = THIS_MODULE,
+ .ctr = dmu_ctr,
+ .dtr = dmu_dtr,
+ .map = dmu_map,
+ .status = dmu_status,
+ .end_io = dmu_end_io
+};
+
+int __init dm_userspace_init(void)
+{
+ int r = dm_register_target(&userspace_target);
+ if (r < 0) {
+ DMERR("Register failed %d", r);
+ return 0;
+ }
+
+ spin_lock_init(&devices_lock);
+
+ request_cache =
+ kmem_cache_create("dm-userspace-requests",
+ sizeof(struct dmu_request),
+ __alignof__ (struct dmu_request),
+ 0, NULL, NULL);
+ if (!request_cache) {
+ DMERR("Failed to allocate request cache");
+ goto bad;
+ }
+
+ request_pool = mempool_create(64,
+ mempool_alloc_slab, mempool_free_slab,
+ request_cache);
+ if (!request_pool) {
+ DMERR("Failed to allocate request pool");
+ goto bad2;
+ }
+
+ r = init_chardev_transport();
+ if (!r)
+ goto bad3;
+
+ return 1;
+
+ bad3:
+ mempool_destroy(request_pool);
+ bad2:
+ kmem_cache_destroy(request_cache);
+ bad:
+ dm_unregister_target(&userspace_target);
+
+ return 0;
+}
+
+void __exit dm_userspace_exit(void)
+{
+ int r;
+ struct list_head *cursor, *next;
+ struct dmu_device *dev;
+
+ spin_lock(&devices_lock);
+
+ list_for_each_safe(cursor, next, &devices) {
+ dev = list_entry(cursor, struct dmu_device, list);
+ list_del(cursor);
+ destroy_dmu_device(&dev->users);
+ DMERR("Destroying hanging device %s", dev->key);
+ }
+
+ spin_unlock(&devices_lock);
+
+ cleanup_chardev_transport();
+
+ mempool_destroy(request_pool);
+ kmem_cache_destroy(request_cache);
+
+ r = dm_unregister_target(&userspace_target);
+ if (r < 0)
+ DMERR("unregister failed %d", r);
+}
+
+module_init(dm_userspace_init);
+module_exit(dm_userspace_exit);
+
+MODULE_DESCRIPTION(DM_NAME " userspace target");
+MODULE_AUTHOR("Dan Smith");
+MODULE_LICENSE("GPL");
diff -Naur linux-2.6.18-orig/drivers/md/dm-userspace-chardev.c linux-2.6.18-dmu/drivers/md/dm-userspace-chardev.c
--- linux-2.6.18-orig/drivers/md/dm-userspace-chardev.c 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.18-dmu/drivers/md/dm-userspace-chardev.c 2006-09-28 13:49:18.000000000 -0700
@@ -0,0 +1,598 @@
+/*
+ * Copyright (C) International Business Machines Corp., 2006
+ * Author: Dan Smith <danms@xxxxxxxxxx>
+ *
+ * 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; under version 2 of the License.
+ *
+ * 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; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#include <linux/spinlock.h>
+#include <linux/blkdev.h>
+#include <linux/mempool.h>
+#include <linux/dm-userspace.h>
+#include <linux/list.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/poll.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <asm/uaccess.h>
+
+#include "dm.h"
+#include "dm-bio-list.h"
+#include "kcopyd.h"
+#include "dm-user.h"
+
+#define DM_MSG_PREFIX "dm-userspace"
+
+/* This allows for a cleaner separation between the dm-userspace
+ * device-mapper target, and the userspace transport used. Right now,
+ * only a chardev transport exists, but it's possible that there could
+ * be more in the future
+ */
+struct chardev_transport {
+ struct cdev cdev;
+ dev_t ctl_dev;
+ struct dmu_device *parent;
+};
+
+static struct dmu_request *find_rx_request(struct dmu_device *dev,
+ uint64_t id)
+{
+ struct dmu_request *req, *next, *match = NULL;
+
+ spin_lock(&dev->lock);
+ list_for_each_entry_safe(req, next, &dev->rx_requests, list) {
+ if (req->id == id) {
+ list_del_init(&req->list);
+ match = req;
+ atomic_dec(&dev->r_reqs);
+ break;
+ }
+ }
+ spin_unlock(&dev->lock);
+
+ return match;
+}
+
+static int have_pending_requests(struct dmu_device *dev)
+{
+ return atomic_read(&dev->t_reqs) != 0;
+}
+
+static int send_userspace_message(uint8_t __user *buffer,
+ struct dmu_request *req)
+{
+ int ret = 0;
+ struct dmu_msg msg;
+
+ memset(&msg, 0, sizeof(msg));
+
+ msg.hdr.id = req->id;
+
+ switch (req->type) {
+ case DM_USERSPACE_MAP_BLOCK_REQ:
+ msg.hdr.msg_type = req->type;
+ msg.payload.map_req.org_block = req->u.block;
+ dmu_cpy_flag(&msg.payload.map_req.flags,
+ req->flags, DMU_FLAG_WR);
+ break;
+
+ case DM_USERSPACE_MAP_DONE:
+ msg.hdr.msg_type = DM_USERSPACE_MAP_DONE;
+ msg.payload.map_done.id_of_op = req->id;
+ msg.payload.map_done.org_block = req->u.block;
+ dmu_cpy_flag(&msg.payload.map_done.flags,
+ req->flags, DMU_FLAG_WR);
+ break;
+
+ default:
+ DMWARN("Unknown outgoing message type %i", req->type);
+ ret = 0;
+ }
+
+ if (copy_to_user(buffer, &msg, sizeof(msg)))
+ return -EFAULT;
+
+ ret = sizeof(msg);
+
+ /* If this request is not on a list (the rx_requests list),
+ * then it needs to be freed after sending
+ */
+ if (list_empty(&req->list))
+ mempool_free(req, request_pool);
+
+ return ret;
+}
+
+struct dmu_request *pluck_next_request(struct dmu_device *dev)
+{
+ struct dmu_request *req = NULL;
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev->tx_lock, flags);
+ if (!list_empty(&dev->tx_requests)) {
+ req = list_entry(dev->tx_requests.next,
+ struct dmu_request, list);
+ list_del_init(&req->list);
+
+ atomic_dec(&dev->t_reqs);
+ }
+ spin_unlock_irqrestore(&dev->tx_lock, flags);
+
+ if (req && ((req->type == DM_USERSPACE_MAP_BLOCK_REQ) ||
+ (req->type == DM_USERSPACE_MAP_DONE))) {
+ spin_lock(&dev->lock);
+ list_add_tail(&req->list, &dev->rx_requests);
+ atomic_inc(&dev->r_reqs);
+ spin_unlock(&dev->lock);
+ }
+
+ return req;
+}
+
+ssize_t dmu_ctl_read(struct file *file, char __user *buffer,
+ size_t size, loff_t *offset)
+{
+
+ struct dmu_device *dev = (struct dmu_device *)file->private_data;
+ struct dmu_request *req = NULL;
+ int ret = 0, r;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EACCES;
+
+ if (size < sizeof(struct dmu_msg)) {
+ DMERR("Userspace buffer too small for a single message");
+ return 0;
+ }
+
+ while (!have_pending_requests(dev)) {
+ if (file->f_flags & O_NONBLOCK) {
+ return 0;
+ }
+
+ if (wait_event_interruptible(dev->wqueue,
+ have_pending_requests(dev)))
+ return -ERESTARTSYS;
+ }
+
+ while (ret < size) {
+ if ((size - ret) < sizeof(struct dmu_msg))
+ break;
+
+ req = pluck_next_request(dev);
+ if (!req)
+ break;
+
+ r = send_userspace_message((void *)(buffer + ret), req);
+ if (r == 0)
+ continue;
+ else if (r < 0)
+ return r;
+
+ ret += r;
+ }
+
+ if (ret < sizeof(struct dmu_msg)) {
+ if (ret != 0)
+ DMERR("Sending partial message!");
+ DMINFO("Sent 0 requests to userspace");
+ }
+
+ return ret;
+}
+
+static struct dmu_request *pluck_dep_req(struct dmu_request *req)
+{
+ struct dmu_request *dreq = NULL;
+
+ if (list_empty(&req->deps)) {
+ /* Delete from cp_requests */
+ list_del_init(&req->copy);
+ } else {
+ /* Get next dependent request */
+ dreq = list_entry(req->deps.next, struct dmu_request, list);
+ list_del_init(&dreq->list);
+ }
+
+ return dreq;
+}
+
+static void flush_block(int read_err, unsigned int write_err, void *data)
+{
+ struct dmu_request *req = data;
+ struct dmu_request *dreq;
+ uint64_t id = req->id;
+
+ if (read_err || write_err) {
+ DMERR("Failed to copy block!");
+ bio_io_error(req->bio, req->bio->bi_size);
+ while ((dreq = pluck_dep_req(req))) {
+ bio_io_error(dreq->bio, dreq->bio->bi_size);
+ }
+ return;
+ }
+
+ atomic_inc(&req->dev->f_reqs);
+ generic_make_request(req->bio);
+
+ down(&req->dev->cp_sem);
+ while ((dreq = pluck_dep_req(req))) {
+ if (id > dreq->id) {
+ printk(KERN_EMERG "Flushing %llu after %llu\n",
+ dreq->id, id);
+ }
+ id = dreq->id;
+ atomic_inc(&req->dev->f_reqs);
+ generic_make_request(dreq->bio);
+ }
+ up(&req->dev->cp_sem);
+}
+
+static void copy_block(struct dmu_device *dev,
+ struct block_device *src_dev,
+ struct block_device *dst_dev,
+ struct dmu_request *req,
+ uint64_t org_block,
+ uint64_t new_block,
+ int64_t offset)
+{
+ struct io_region src, dst;
+
+ src.bdev = src_dev;
+ src.sector = dmu_sector(dev, org_block);
+ src.count = dev->block_size;
+
+ dst.bdev = dst_dev;
+ dst.sector = dmu_sector(dev, new_block);
+ dst.sector += offset;
+ dst.count = dev->block_size;
+
+ kcopyd_copy(dev->kcopy, &src, 1, &dst, 0, flush_block, req);
+}
+
+/*
+ * Queues @req with a waiting request to the same block, if one
+ * exists. Returns nonzero if queued.
+ */
+static int maybe_queue_dependent_request(struct dmu_request *req,
+ int is_copy_first)
+{
+ struct dmu_request *dreq = NULL;
+ int found = 0;
+
+ BUG_ON(!list_empty(&req->list));
+
+ down(&req->dev->cp_sem);
+
+ list_for_each_entry(dreq, &req->dev->cp_requests, copy) {
+ if (req->u.block == dreq->u.block) {
+ list_add_tail(&req->list, &dreq->deps);
+ found = 1;
+ break;
+ }
+ }
+
+ if (!found && is_copy_first) {
+ BUG_ON(!list_empty(&req->copy));
+ list_add(&req->copy, &req->dev->cp_requests);
+ }
+
+ up(&req->dev->cp_sem);
+
+ return found;
+}
+
+static void map_worker(void *data)
+{
+ struct dmu_request *req = data;
+ struct dmu_msg_map_response *msg = &req->response;
+ struct dmu_device *dev = req->dev;
+ struct target_device *src_dev, *dst_dev;
+ int need_copy = dmu_get_flag(&msg->flags, DMU_FLAG_COPY_FIRST);
+
+ if (dmu_get_flag(&msg->flags, DMU_FLAG_COPY_FIRST)) {
+ src_dev = find_target(dev, MKDEV(msg->src_maj, msg->src_min));
+ if (!src_dev) {
+ DMERR("Failed to find src device %i:%i\n",
+ msg->src_maj, msg->src_min);
+ goto fail;
+ }
+ } else
+ src_dev = NULL;
+
+ dst_dev = find_target(dev, MKDEV(msg->dst_maj, msg->dst_min));
+ if (!dst_dev) {
+ DMERR("Failed to find dest device %i:%i\n",
+ msg->dst_maj, msg->dst_min);
+ goto fail;
+ }
+
+ /* Remap the bio */
+ req->bio->bi_sector = dmu_sector(dev, msg->new_block) +
+ dmu_sector_offset(dev, req->bio->bi_sector) +
+ msg->offset;
+ req->bio->bi_bdev = dst_dev->bdev;
+
+ dmu_set_flag(&req->flags, DMU_FLAG_SYNC);
+
+ if (!maybe_queue_dependent_request(req, need_copy)) {
+ if (need_copy)
+ copy_block(dev, src_dev->bdev, dst_dev->bdev, req,
+ req->u.block, msg->new_block,
+ msg->offset);
+ else
+ flush_block(0, 0, req);
+ }
+
+ return;
+
+ fail:
+ bio_io_error(req->bio, req->bio->bi_size);
+}
+
+static void do_map_bio(struct dmu_device *dev,
+ struct dmu_msg_map_response *msg)
+{
+ struct dmu_request *req;
+
+ req = find_rx_request(dev, msg->id_of_req);
+ if (!req) {
+ DMERR("Unable to complete unknown map: %llu\n",
+ msg->id_of_req);
+ return;
+ }
+
+ memcpy(&req->response, msg, sizeof(req->response));
+
+#if 0
+ /* I think it would be nice to farm this out to a worker
+ * thread, so that userspace does not have to do all the work,
+ * but I wonder about the correctness of possibly reordering
+ * requests to a single block
+ */
+ INIT_WORK(&req->task, map_worker, req);
+ schedule_work(&req->task);
+#else
+ map_worker(req);
+#endif
+}
+
+static void do_map_done(struct dmu_device *dev, uint64_t id_of_op, int fail)
+{
+ struct dmu_request *req;
+
+ req = find_rx_request(dev, id_of_op);
+ if (!req) {
+ DMERR("Unable to complete unknown request: %llu\n",
+ id_of_op);
+ return;
+ }
+
+ dmu_clr_flag(&req->flags, DMU_FLAG_SYNC);
+
+ req->bio->bi_end_io(req->bio, req->bio->bi_size, fail);
+}
+
+static void do_map_failed(struct dmu_device *dev, uint64_t id_of_op)
+{
+ struct dmu_request *req;
+
+ req = find_rx_request(dev, id_of_op);
+ if (!req) {
+ DMERR("Unable to fail unknown request: %llu\n",
+ id_of_op);
+ return;
+ }
+
+ DMERR("Userspace failed to map id %llu (sector %llu)",
+ id_of_op, req->bio->bi_sector);
+
+ bio_io_error(req->bio, req->bio->bi_size);
+
+ mempool_free(req, request_pool);
+}
+
+ssize_t dmu_ctl_write(struct file *file, const char __user *buffer,
+ size_t size, loff_t *offset)
+{
+ struct dmu_device *dev = (struct dmu_device *)file->private_data;
+ int ret = 0;
+ struct dmu_msg msg;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EACCES;
+
+ while ((ret + sizeof(msg)) <= size) {
+ if (copy_from_user(&msg, buffer+ret, sizeof(msg))) {
+ DMERR("%s copy_from_user failed!", __FUNCTION__);
+ ret = -EFAULT;
+ goto out;
+ }
+
+ ret += sizeof(msg);
+
+ switch (msg.hdr.msg_type) {
+ case DM_USERSPACE_MAP_BLOCK_RESP:
+ do_map_bio(dev, &msg.payload.map_rsp);
+ break;
+
+ case DM_USERSPACE_MAP_FAILED:
+ do_map_failed(dev, msg.payload.map_rsp.id_of_req);
+ break;
+
+ case DM_USERSPACE_MAP_DONE:
+ do_map_done(dev, msg.payload.map_done.id_of_op, 0);
+ break;
+
+ case DM_USERSPACE_MAP_DONE_FAILED:
+ do_map_done(dev, msg.payload.map_done.id_of_op, 1);
+ break;
+
+ default:
+ DMWARN("Unknown incoming request type: %i",
+ msg.hdr.msg_type);
+ }
+ }
+ out:
+ if (ret < sizeof(msg)) {
+ DMINFO("Received 0 responses from userspace");
+ }
+
+ return ret;
+}
+
+int dmu_ctl_open(struct inode *inode, struct file *file)
+{
+ struct chardev_transport *t;
+ struct dmu_device *dev;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EACCES;
+
+ t = container_of(inode->i_cdev, struct chardev_transport, cdev);
+ dev = t->parent;
+
+ get_dev(dev);
+
+ file->private_data = dev;
+
+ return 0;
+}
+
+int dmu_ctl_release(struct inode *inode, struct file *file)
+{
+ struct dmu_device *dev;
+
+ dev = (struct dmu_device *)file->private_data;
+
+ put_dev(dev);
+
+ return 0;
+}
+
+unsigned dmu_ctl_poll(struct file *file, poll_table *wait)
+{
+ struct dmu_device *dev = (struct dmu_device *)file->private_data;
+ unsigned mask = 0;
+
+ poll_wait(file, &dev->wqueue, wait);
+
+ if (have_pending_requests(dev))
+ mask |= POLLIN | POLLRDNORM;
+
+ return mask;
+}
+
+static struct file_operations ctl_fops = {
+ .open = dmu_ctl_open,
+ .release = dmu_ctl_release,
+ .read = dmu_ctl_read,
+ .write = dmu_ctl_write,
+ .poll = dmu_ctl_poll,
+ .owner = THIS_MODULE,
+};
+
+static int get_free_minor(void)
+{
+ struct dmu_device *dev;
+ int minor = 0;
+
+ spin_lock(&devices_lock);
+
+ while (1) {
+ list_for_each_entry(dev, &devices, list) {
+ struct chardev_transport *t = dev->transport_private;
+ if (MINOR(t->ctl_dev) == minor)
+ goto dupe;
+ }
+ break;
+ dupe:
+ minor++;
+ }
+
+ spin_unlock(&devices_lock);
+
+ return minor;
+}
+
+int register_chardev_transport(struct dmu_device *dev)
+{
+ struct chardev_transport *t;
+ int ret;
+
+ dev->transport_private = kmalloc(sizeof(struct chardev_transport),
+ GFP_KERNEL);
+ t = dev->transport_private;
+
+ if (!t) {
+ DMERR("Failed to allocate chardev transport");
+ goto bad;
+ }
+
+ t->ctl_dev = MKDEV(MAJOR(dmu_dev), get_free_minor());
+ t->parent = dev;
+
+ cdev_init(&t->cdev, &ctl_fops);
+ t->cdev.owner = THIS_MODULE;
+ t->cdev.ops = &ctl_fops;
+
+ ret = cdev_add(&t->cdev, t->ctl_dev, 1);
+ if (ret < 0) {
+ DMERR("Failed to register control device %d:%d",
+ MAJOR(t->ctl_dev), MINOR(t->ctl_dev));
+ goto bad;
+ }
+
+ return 1;
+
+ bad:
+ kfree(t);
+ return 0;
+}
+
+void unregister_chardev_transport(struct dmu_device *dev)
+{
+ struct chardev_transport *t = dev->transport_private;
+
+ cdev_del(&t->cdev);
+ kfree(t);
+}
+
+int init_chardev_transport(void)
+{
+ int r;
+
+ r = alloc_chrdev_region(&dmu_dev, 0, 10, "dm-userspace");
+ if (r) {
+ DMERR("Failed to allocate chardev region");
+ return 0;
+ } else
+ return 1;
+}
+
+void cleanup_chardev_transport(void)
+{
+ unregister_chrdev_region(dmu_dev, 10);
+}
+
+void write_chardev_transport_info(struct dmu_device *dev,
+ char *buf, unsigned int maxlen)
+{
+ struct chardev_transport *t = dev->transport_private;
+
+ snprintf(buf, maxlen, "%x:%x",
+ MAJOR(t->ctl_dev), MINOR(t->ctl_dev));
+}
diff -Naur linux-2.6.18-orig/drivers/md/Kconfig linux-2.6.18-dmu/drivers/md/Kconfig
--- linux-2.6.18-orig/drivers/md/Kconfig 2006-09-19 20:42:06.000000000 -0700
+++ linux-2.6.18-dmu/drivers/md/Kconfig 2006-09-28 13:49:18.000000000 -0700
@@ -223,6 +223,12 @@
---help---
Allow volume managers to take writable snapshots of a device.
+config DM_USERSPACE
+ tristate "Userspace target (EXPERIMENTAL)"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ A target that provides a userspace interface to device-mapper
+
config DM_MIRROR
tristate "Mirror target (EXPERIMENTAL)"
depends on BLK_DEV_DM && EXPERIMENTAL
diff -Naur linux-2.6.18-orig/drivers/md/Kconfig.orig linux-2.6.18-dmu/drivers/md/Kconfig.orig
--- linux-2.6.18-orig/drivers/md/Kconfig.orig 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.18-dmu/drivers/md/Kconfig.orig 2006-09-19 20:42:06.000000000 -0700
@@ -0,0 +1,253 @@
+#
+# Block device driver configuration
+#
+
+menu "Multi-device support (RAID and LVM)"
+
+config MD
+ bool "Multiple devices driver support (RAID and LVM)"
+ help
+ Support multiple physical spindles through a single logical device.
+ Required for RAID and logical volume management.
+
+config BLK_DEV_MD
+ tristate "RAID support"
+ depends on MD
+ ---help---
+ This driver lets you combine several hard disk partitions into one
+ logical block device. This can be used to simply append one
+ partition to another one or to combine several redundant hard disks
+ into a RAID1/4/5 device so as to provide protection against hard
+ disk failures. This is called "Software RAID" since the combining of
+ the partitions is done by the kernel. "Hardware RAID" means that the
+ combining is done by a dedicated controller; if you have such a
+ controller, you do not need to say Y here.
+
+ More information about Software RAID on Linux is contained in the
+ Software RAID mini-HOWTO, available from
+ <http://www.tldp.org/docs.html#howto>. There you will also learn
+ where to get the supporting user space utilities raidtools.
+
+ If unsure, say N.
+
+config MD_LINEAR
+ tristate "Linear (append) mode"
+ depends on BLK_DEV_MD
+ ---help---
+ If you say Y here, then your multiple devices driver will be able to
+ use the so-called linear mode, i.e. it will combine the hard disk
+ partitions by simply appending one to the other.
+
+ To compile this as a module, choose M here: the module
+ will be called linear.
+
+ If unsure, say Y.
+
+config MD_RAID0
+ tristate "RAID-0 (striping) mode"
+ depends on BLK_DEV_MD
+ ---help---
+ If you say Y here, then your multiple devices driver will be able to
+ use the so-called raid0 mode, i.e. it will combine the hard disk
+ partitions into one logical device in such a fashion as to fill them
+ up evenly, one chunk here and one chunk there. This will increase
+ the throughput rate if the partitions reside on distinct disks.
+
+ Information about Software RAID on Linux is contained in the
+ Software-RAID mini-HOWTO, available from
+ <http://www.tldp.org/docs.html#howto>. There you will also
+ learn where to get the supporting user space utilities raidtools.
+
+ To compile this as a module, choose M here: the module
+ will be called raid0.
+
+ If unsure, say Y.
+
+config MD_RAID1
+ tristate "RAID-1 (mirroring) mode"
+ depends on BLK_DEV_MD
+ ---help---
+ A RAID-1 set consists of several disk drives which are exact copies
+ of each other. In the event of a mirror failure, the RAID driver
+ will continue to use the operational mirrors in the set, providing
+ an error free MD (multiple device) to the higher levels of the
+ kernel. In a set with N drives, the available space is the capacity
+ of a single drive, and the set protects against a failure of (N - 1)
+ drives.
+
+ Information about Software RAID on Linux is contained in the
+ Software-RAID mini-HOWTO, available from
+ <http://www.tldp.org/docs.html#howto>. There you will also
+ learn where to get the supporting user space utilities raidtools.
+
+ If you want to use such a RAID-1 set, say Y. To compile this code
+ as a module, choose M here: the module will be called raid1.
+
+ If unsure, say Y.
+
+config MD_RAID10
+ tristate "RAID-10 (mirrored striping) mode (EXPERIMENTAL)"
+ depends on BLK_DEV_MD && EXPERIMENTAL
+ ---help---
+ RAID-10 provides a combination of striping (RAID-0) and
+ mirroring (RAID-1) with easier configuration and more flexible
+ layout.
+ Unlike RAID-0, but like RAID-1, RAID-10 requires all devices to
+ be the same size (or at least, only as much as the smallest device
+ will be used).
+ RAID-10 provides a variety of layouts that provide different levels
+ of redundancy and performance.
+
+ RAID-10 requires mdadm-1.7.0 or later, available at:
+
+ ftp://ftp.kernel.org/pub/linux/utils/raid/mdadm/
+
+ If unsure, say Y.
+
+config MD_RAID456
+ tristate "RAID-4/RAID-5/RAID-6 mode"
+ depends on BLK_DEV_MD
+ ---help---
+ A RAID-5 set of N drives with a capacity of C MB per drive provides
+ the capacity of C * (N - 1) MB, and protects against a failure
+ of a single drive. For a given sector (row) number, (N - 1) drives
+ contain data sectors, and one drive contains the parity protection.
+ For a RAID-4 set, the parity blocks are present on a single drive,
+ while a RAID-5 set distributes the parity across the drives in one
+ of the available parity distribution methods.
+
+ A RAID-6 set of N drives with a capacity of C MB per drive
+ provides the capacity of C * (N - 2) MB, and protects
+ against a failure of any two drives. For a given sector
+ (row) number, (N - 2) drives contain data sectors, and two
+ drives contains two independent redundancy syndromes. Like
+ RAID-5, RAID-6 distributes the syndromes across the drives
+ in one of the available parity distribution methods.
+
+ Information about Software RAID on Linux is contained in the
+ Software-RAID mini-HOWTO, available from
+ <http://www.tldp.org/docs.html#howto>. There you will also
+ learn where to get the supporting user space utilities raidtools.
+
+ If you want to use such a RAID-4/RAID-5/RAID-6 set, say Y. To
+ compile this code as a module, choose M here: the module
+ will be called raid456.
+
+ If unsure, say Y.
+
+config MD_RAID5_RESHAPE
+ bool "Support adding drives to a raid-5 array (experimental)"
+ depends on MD_RAID456 && EXPERIMENTAL
+ ---help---
+ A RAID-5 set can be expanded by adding extra drives. This
+ requires "restriping" the array which means (almost) every
+ block must be written to a different place.
+
+ This option allows such restriping to be done while the array
+ is online. However it is still EXPERIMENTAL code. It should
+ work, but please be sure that you have backups.
+
+ You will need mdadm version 2.4.1 or later to use this
+ feature safely. During the early stage of reshape there is
+ a critical section where live data is being over-written. A
+ crash during this time needs extra care for recovery. The
+ newer mdadm takes a copy of the data in the critical section
+ and will restore it, if necessary, after a crash.
+
+ The mdadm usage is e.g.
+ mdadm --grow /dev/md1 --raid-disks=6
+ to grow '/dev/md1' to having 6 disks.
+
+ Note: The array can only be expanded, not contracted.
+ There should be enough spares already present to make the new
+ array workable.
+
+config MD_MULTIPATH
+ tristate "Multipath I/O support"
+ depends on BLK_DEV_MD
+ help
+ Multipath-IO is the ability of certain devices to address the same
+ physical disk over multiple 'IO paths'. The code ensures that such
+ paths can be defined and handled at runtime, and ensures that a
+ transparent failover to the backup path(s) happens if a IO errors
+ arrives on the primary path.
+
+ If unsure, say N.
+
+config MD_FAULTY
+ tristate "Faulty test module for MD"
+ depends on BLK_DEV_MD
+ help
+ The "faulty" module allows for a block device that occasionally returns
+ read or write errors. It is useful for testing.
+
+ In unsure, say N.
+
+config BLK_DEV_DM
+ tristate "Device mapper support"
+ depends on MD
+ ---help---
+ Device-mapper is a low level volume manager. It works by allowing
+ people to specify mappings for ranges of logical sectors. Various
+ mapping types are available, in addition people may write their own
+ modules containing custom mappings if they wish.
+
+ Higher level volume managers such as LVM2 use this driver.
+
+ To compile this as a module, choose M here: the module will be
+ called dm-mod.
+
+ If unsure, say N.
+
+config DM_CRYPT
+ tristate "Crypt target support"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ select CRYPTO
+ ---help---
+ This device-mapper target allows you to create a device that
+ transparently encrypts the data on it. You'll need to activate
+ the ciphers you're going to use in the cryptoapi configuration.
+
+ Information on how to use dm-crypt can be found on
+
+ <http://www.saout.de/misc/dm-crypt/>
+
+ To compile this code as a module, choose M here: the module will
+ be called dm-crypt.
+
+ If unsure, say N.
+
+config DM_SNAPSHOT
+ tristate "Snapshot target (EXPERIMENTAL)"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ Allow volume managers to take writable snapshots of a device.
+
+config DM_MIRROR
+ tristate "Mirror target (EXPERIMENTAL)"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ Allow volume managers to mirror logical volumes, also
+ needed for live data migration tools such as 'pvmove'.
+
+config DM_ZERO
+ tristate "Zero target (EXPERIMENTAL)"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ A target that discards writes, and returns all zeroes for
+ reads. Useful in some recovery situations.
+
+config DM_MULTIPATH
+ tristate "Multipath target (EXPERIMENTAL)"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ Allow volume managers to support multipath hardware.
+
+config DM_MULTIPATH_EMC
+ tristate "EMC CX/AX multipath support (EXPERIMENTAL)"
+ depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL
+ ---help---
+ Multipath support for EMC CX/AX series hardware.
+
+endmenu
+
diff -Naur linux-2.6.18-orig/drivers/md/Makefile linux-2.6.18-dmu/drivers/md/Makefile
--- linux-2.6.18-orig/drivers/md/Makefile 2006-09-19 20:42:06.000000000 -0700
+++ linux-2.6.18-dmu/drivers/md/Makefile 2006-09-28 13:49:18.000000000 -0700
@@ -14,6 +14,7 @@
raid6altivec1.o raid6altivec2.o raid6altivec4.o \
raid6altivec8.o \
raid6mmx.o raid6sse1.o raid6sse2.o
+dm-user-objs := dm-userspace.o dm-userspace-chardev.o
hostprogs-y := mktables
# Note: link order is important. All raid personalities
@@ -36,6 +37,7 @@
obj-$(CONFIG_DM_SNAPSHOT) += dm-snapshot.o
obj-$(CONFIG_DM_MIRROR) += dm-mirror.o
obj-$(CONFIG_DM_ZERO) += dm-zero.o
+obj-$(CONFIG_DM_USERSPACE) += dm-user.o
quiet_cmd_unroll = UNROLL $@
cmd_unroll = $(PERL) $(srctree)/$(src)/unroll.pl $(UNROLL) \
diff -Naur linux-2.6.18-orig/drivers/md/Makefile.orig linux-2.6.18-dmu/drivers/md/Makefile.orig
--- linux-2.6.18-orig/drivers/md/Makefile.orig 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.18-dmu/drivers/md/Makefile.orig 2006-09-19 20:42:06.000000000 -0700
@@ -0,0 +1,107 @@
+#
+# Makefile for the kernel software RAID and LVM drivers.
+#
+
+dm-mod-objs := dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
+ dm-ioctl.o dm-io.o kcopyd.o
+dm-multipath-objs := dm-hw-handler.o dm-path-selector.o dm-mpath.o
+dm-snapshot-objs := dm-snap.o dm-exception-store.o
+dm-mirror-objs := dm-log.o dm-raid1.o
+md-mod-objs := md.o bitmap.o
+raid456-objs := raid5.o raid6algos.o raid6recov.o raid6tables.o \
+ raid6int1.o raid6int2.o raid6int4.o \
+ raid6int8.o raid6int16.o raid6int32.o \
+ raid6altivec1.o raid6altivec2.o raid6altivec4.o \
+ raid6altivec8.o \
+ raid6mmx.o raid6sse1.o raid6sse2.o
+hostprogs-y := mktables
+
+# Note: link order is important. All raid personalities
+# and xor.o must come before md.o, as they each initialise
+# themselves, and md.o may use the personalities when it
+# auto-initialised.
+
+obj-$(CONFIG_MD_LINEAR) += linear.o
+obj-$(CONFIG_MD_RAID0) += raid0.o
+obj-$(CONFIG_MD_RAID1) += raid1.o
+obj-$(CONFIG_MD_RAID10) += raid10.o
+obj-$(CONFIG_MD_RAID456) += raid456.o xor.o
+obj-$(CONFIG_MD_MULTIPATH) += multipath.o
+obj-$(CONFIG_MD_FAULTY) += faulty.o
+obj-$(CONFIG_BLK_DEV_MD) += md-mod.o
+obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o
+obj-$(CONFIG_DM_CRYPT) += dm-crypt.o
+obj-$(CONFIG_DM_MULTIPATH) += dm-multipath.o dm-round-robin.o
+obj-$(CONFIG_DM_MULTIPATH_EMC) += dm-emc.o
+obj-$(CONFIG_DM_SNAPSHOT) += dm-snapshot.o
+obj-$(CONFIG_DM_MIRROR) += dm-mirror.o
+obj-$(CONFIG_DM_ZERO) += dm-zero.o
+
+quiet_cmd_unroll = UNROLL $@
+ cmd_unroll = $(PERL) $(srctree)/$(src)/unroll.pl $(UNROLL) \
+ < $< > $@ || ( rm -f $@ && exit 1 )
+
+ifeq ($(CONFIG_ALTIVEC),y)
+altivec_flags := -maltivec -mabi=altivec
+endif
+
+targets += raid6int1.c
+$(obj)/raid6int1.c: UNROLL := 1
+$(obj)/raid6int1.c: $(src)/raid6int.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+targets += raid6int2.c
+$(obj)/raid6int2.c: UNROLL := 2
+$(obj)/raid6int2.c: $(src)/raid6int.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+targets += raid6int4.c
+$(obj)/raid6int4.c: UNROLL := 4
+$(obj)/raid6int4.c: $(src)/raid6int.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+targets += raid6int8.c
+$(obj)/raid6int8.c: UNROLL := 8
+$(obj)/raid6int8.c: $(src)/raid6int.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+targets += raid6int16.c
+$(obj)/raid6int16.c: UNROLL := 16
+$(obj)/raid6int16.c: $(src)/raid6int.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+targets += raid6int32.c
+$(obj)/raid6int32.c: UNROLL := 32
+$(obj)/raid6int32.c: $(src)/raid6int.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+CFLAGS_raid6altivec1.o += $(altivec_flags)
+targets += raid6altivec1.c
+$(obj)/raid6altivec1.c: UNROLL := 1
+$(obj)/raid6altivec1.c: $(src)/raid6altivec.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+CFLAGS_raid6altivec2.o += $(altivec_flags)
+targets += raid6altivec2.c
+$(obj)/raid6altivec2.c: UNROLL := 2
+$(obj)/raid6altivec2.c: $(src)/raid6altivec.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+CFLAGS_raid6altivec4.o += $(altivec_flags)
+targets += raid6altivec4.c
+$(obj)/raid6altivec4.c: UNROLL := 4
+$(obj)/raid6altivec4.c: $(src)/raid6altivec.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+CFLAGS_raid6altivec8.o += $(altivec_flags)
+targets += raid6altivec8.c
+$(obj)/raid6altivec8.c: UNROLL := 8
+$(obj)/raid6altivec8.c: $(src)/raid6altivec.uc $(src)/unroll.pl FORCE
+ $(call if_changed,unroll)
+
+quiet_cmd_mktable = TABLE $@
+ cmd_mktable = $(obj)/mktables > $@ || ( rm -f $@ && exit 1 )
+
+targets += raid6tables.c
+$(obj)/raid6tables.c: $(obj)/mktables FORCE
+ $(call if_changed,mktable)
diff -Naur linux-2.6.18-orig/include/linux/dm-userspace.h linux-2.6.18-dmu/include/linux/dm-userspace.h
--- linux-2.6.18-orig/include/linux/dm-userspace.h 1969-12-31 16:00:00.000000000 -0800
+++ linux-2.6.18-dmu/include/linux/dm-userspace.h 2006-09-28 13:49:18.000000000 -0700
@@ -0,0 +1,115 @@
+/*
+ * Copyright (C) International Business Machines Corp., 2006
+ * Author: Dan Smith <danms@xxxxxxxxxx>
+ *
+ * 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; under version 2 of the License.
+ *
+ * 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; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#ifndef __DM_USERSPACE_H
+#define __DM_USERSPACE_H
+
+#include <linux/types.h>
+
+/*
+ * Message Types
+ */
+#define DM_USERSPACE_MAP_BLOCK_REQ 1
+#define DM_USERSPACE_MAP_BLOCK_RESP 2
+#define DM_USERSPACE_MAP_FAILED 3
+#define DM_USERSPACE_MAP_DONE 4
+#define DM_USERSPACE_MAP_DONE_FAILED 5
+
+/*
+ * Flags and associated macros
+ */
+#define DMU_FLAG_VALID 1
+#define DMU_FLAG_WR 2
+#define DMU_FLAG_COPY_FIRST 4
+#define DMU_FLAG_SYNC 8
+
+static inline int dmu_get_flag(uint32_t *flags, uint32_t flag)
+{
+ return (*flags & flag) != 0;
+}
+
+static inline void dmu_set_flag(uint32_t *flags, uint32_t flag)
+{
+ *flags |= flag;
+}
+
+static inline void dmu_clr_flag(uint32_t *flags, uint32_t flag)
+{
+ *flags &= (~flag);
+}
+
+static inline void dmu_cpy_flag(uint32_t *flags, uint32_t src, uint32_t flag)
+{
+ *flags = (*flags & ~flag) | (src & flag);
+}
+
+/*
+ * This message header is sent in front of every message, in both
+ * directions
+ */
+struct dmu_msg_header {
+ uint64_t id;
+ uint32_t msg_type;
+ uint32_t payload_len;
+};
+
+/* DM_USERSPACE_MAP_DONE
+ * DM_USERSPACE_MAP_DONE_FAILED
+ */
+struct dmu_msg_map_done {
+ uint64_t id_of_op;
+ uint64_t org_block;
+ uint32_t flags;
+};
+
+/* DM_USERSPACE_MAP_BLOCK_REQ */
+struct dmu_msg_map_request {
+ uint64_t org_block;
+
+ uint32_t flags;
+};
+
+/* DM_USERSPACE_MAP_BLOCK_RESP
+ * DM_USERSPACE_MAP_BLOCK_FAILED
+ */
+struct dmu_msg_map_response {
+ uint64_t new_block;
+ int64_t offset;
+
+ uint64_t id_of_req;
+ uint32_t flags;
+
+ uint32_t src_maj;
+ uint32_t src_min;
+
+ uint32_t dst_maj;
+ uint32_t dst_min;
+};
+
+/* A full message */
+struct dmu_msg {
+ struct dmu_msg_header hdr;
+ union {
+ struct dmu_msg_map_done map_done;
+ struct dmu_msg_map_request map_req;
+ struct dmu_msg_map_response map_rsp;
+ } payload;
+};
+
+#endif
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