Btrfs: Replace the big fs_mutex with a collection of other locks
[linux-2.6-block.git] / fs / btrfs / volumes.c
index 23ebd95b25e0c267899cad78632b5d1412fa3c93..869864ddcc294ff1c2a0879aedd03654d5cda28a 100644 (file)
@@ -18,6 +18,8 @@
 #include <linux/sched.h>
 #include <linux/bio.h>
 #include <linux/buffer_head.h>
+#include <linux/blkdev.h>
+#include <linux/random.h>
 #include <asm/div64.h>
 #include "ctree.h"
 #include "extent_map.h"
@@ -25,6 +27,7 @@
 #include "transaction.h"
 #include "print-tree.h"
 #include "volumes.h"
+#include "async-thread.h"
 
 struct map_lookup {
        u64 type;
@@ -33,6 +36,7 @@ struct map_lookup {
        int stripe_len;
        int sector_size;
        int num_stripes;
+       int sub_stripes;
        struct btrfs_bio_stripe stripes[];
 };
 
@@ -42,6 +46,16 @@ struct map_lookup {
 static DEFINE_MUTEX(uuid_mutex);
 static LIST_HEAD(fs_uuids);
 
+void btrfs_lock_volumes(void)
+{
+       mutex_lock(&uuid_mutex);
+}
+
+void btrfs_unlock_volumes(void)
+{
+       mutex_unlock(&uuid_mutex);
+}
+
 int btrfs_cleanup_fs_uuids(void)
 {
        struct btrfs_fs_devices *fs_devices;
@@ -56,27 +70,30 @@ int btrfs_cleanup_fs_uuids(void)
                        devices_cur = fs_devices->devices.next;
                        dev = list_entry(devices_cur, struct btrfs_device,
                                         dev_list);
-                       printk("uuid cleanup finds %s\n", dev->name);
                        if (dev->bdev) {
-                               printk("closing\n");
                                close_bdev_excl(dev->bdev);
+                               fs_devices->open_devices--;
                        }
                        list_del(&dev->dev_list);
+                       kfree(dev->name);
                        kfree(dev);
                }
        }
        return 0;
 }
 
-static struct btrfs_device *__find_device(struct list_head *head, u64 devid)
+static struct btrfs_device *__find_device(struct list_head *head, u64 devid,
+                                         u8 *uuid)
 {
        struct btrfs_device *dev;
        struct list_head *cur;
 
        list_for_each(cur, head) {
                dev = list_entry(cur, struct btrfs_device, dev_list);
-               if (dev->devid == devid)
+               if (dev->devid == devid &&
+                   (!uuid || !memcmp(dev->uuid, uuid, BTRFS_UUID_SIZE))) {
                        return dev;
+               }
        }
        return NULL;
 }
@@ -94,6 +111,101 @@ static struct btrfs_fs_devices *find_fsid(u8 *fsid)
        return NULL;
 }
 
+/*
+ * we try to collect pending bios for a device so we don't get a large
+ * number of procs sending bios down to the same device.  This greatly
+ * improves the schedulers ability to collect and merge the bios.
+ *
+ * But, it also turns into a long list of bios to process and that is sure
+ * to eventually make the worker thread block.  The solution here is to
+ * make some progress and then put this work struct back at the end of
+ * the list if the block device is congested.  This way, multiple devices
+ * can make progress from a single worker thread.
+ */
+int run_scheduled_bios(struct btrfs_device *device)
+{
+       struct bio *pending;
+       struct backing_dev_info *bdi;
+       struct bio *tail;
+       struct bio *cur;
+       int again = 0;
+       unsigned long num_run = 0;
+
+       bdi = device->bdev->bd_inode->i_mapping->backing_dev_info;
+loop:
+       spin_lock(&device->io_lock);
+
+       /* take all the bios off the list at once and process them
+        * later on (without the lock held).  But, remember the
+        * tail and other pointers so the bios can be properly reinserted
+        * into the list if we hit congestion
+        */
+       pending = device->pending_bios;
+       tail = device->pending_bio_tail;
+       WARN_ON(pending && !tail);
+       device->pending_bios = NULL;
+       device->pending_bio_tail = NULL;
+
+       /*
+        * if pending was null this time around, no bios need processing
+        * at all and we can stop.  Otherwise it'll loop back up again
+        * and do an additional check so no bios are missed.
+        *
+        * device->running_pending is used to synchronize with the
+        * schedule_bio code.
+        */
+       if (pending) {
+               again = 1;
+               device->running_pending = 1;
+       } else {
+               again = 0;
+               device->running_pending = 0;
+       }
+       spin_unlock(&device->io_lock);
+
+       while(pending) {
+               cur = pending;
+               pending = pending->bi_next;
+               cur->bi_next = NULL;
+               atomic_dec(&device->dev_root->fs_info->nr_async_submits);
+               submit_bio(cur->bi_rw, cur);
+               num_run++;
+
+               /*
+                * we made progress, there is more work to do and the bdi
+                * is now congested.  Back off and let other work structs
+                * run instead
+                */
+               if (pending && num_run && bdi_write_congested(bdi)) {
+                       struct bio *old_head;
+
+                       spin_lock(&device->io_lock);
+                       old_head = device->pending_bios;
+                       device->pending_bios = pending;
+                       if (device->pending_bio_tail)
+                               tail->bi_next = old_head;
+                       else
+                               device->pending_bio_tail = tail;
+
+                       spin_unlock(&device->io_lock);
+                       btrfs_requeue_work(&device->work);
+                       goto done;
+               }
+       }
+       if (again)
+               goto loop;
+done:
+       return 0;
+}
+
+void pending_bios_fn(struct btrfs_work *work)
+{
+       struct btrfs_device *device;
+
+       device = container_of(work, struct btrfs_device, work);
+       run_scheduled_bios(device);
+}
+
 static int device_list_add(const char *path,
                           struct btrfs_super_block *disk_super,
                           u64 devid, struct btrfs_fs_devices **fs_devices_ret)
@@ -104,19 +216,19 @@ static int device_list_add(const char *path,
 
        fs_devices = find_fsid(disk_super->fsid);
        if (!fs_devices) {
-               fs_devices = kmalloc(sizeof(*fs_devices), GFP_NOFS);
+               fs_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
                if (!fs_devices)
                        return -ENOMEM;
                INIT_LIST_HEAD(&fs_devices->devices);
+               INIT_LIST_HEAD(&fs_devices->alloc_list);
                list_add(&fs_devices->list, &fs_uuids);
                memcpy(fs_devices->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
                fs_devices->latest_devid = devid;
                fs_devices->latest_trans = found_transid;
-               fs_devices->lowest_devid = (u64)-1;
-               fs_devices->num_devices = 0;
                device = NULL;
        } else {
-               device = __find_device(&fs_devices->devices, devid);
+               device = __find_device(&fs_devices->devices, devid,
+                                      disk_super->dev_item.uuid);
        }
        if (!device) {
                device = kzalloc(sizeof(*device), GFP_NOFS);
@@ -125,6 +237,9 @@ static int device_list_add(const char *path,
                        return -ENOMEM;
                }
                device->devid = devid;
+               device->work.func = pending_bios_fn;
+               memcpy(device->uuid, disk_super->dev_item.uuid,
+                      BTRFS_UUID_SIZE);
                device->barriers = 1;
                spin_lock_init(&device->io_lock);
                device->name = kstrdup(path, GFP_NOFS);
@@ -133,6 +248,7 @@ static int device_list_add(const char *path,
                        return -ENOMEM;
                }
                list_add(&device->dev_list, &fs_devices->devices);
+               list_add(&device->dev_alloc_list, &fs_devices->alloc_list);
                fs_devices->num_devices++;
        }
 
@@ -140,14 +256,37 @@ static int device_list_add(const char *path,
                fs_devices->latest_devid = devid;
                fs_devices->latest_trans = found_transid;
        }
-       if (fs_devices->lowest_devid > devid) {
-               fs_devices->lowest_devid = devid;
-               printk("lowest devid now %Lu\n", devid);
-       }
        *fs_devices_ret = fs_devices;
        return 0;
 }
 
+int btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices)
+{
+       struct list_head *head = &fs_devices->devices;
+       struct list_head *cur;
+       struct btrfs_device *device;
+
+       mutex_lock(&uuid_mutex);
+again:
+       list_for_each(cur, head) {
+               device = list_entry(cur, struct btrfs_device, dev_list);
+               if (!device->in_fs_metadata) {
+                       if (device->bdev) {
+                               close_bdev_excl(device->bdev);
+                               fs_devices->open_devices--;
+                       }
+                       list_del(&device->dev_list);
+                       list_del(&device->dev_alloc_list);
+                       fs_devices->num_devices--;
+                       kfree(device->name);
+                       kfree(device);
+                       goto again;
+               }
+       }
+       mutex_unlock(&uuid_mutex);
+       return 0;
+}
+
 int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 {
        struct list_head *head = &fs_devices->devices;
@@ -159,10 +298,12 @@ int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                device = list_entry(cur, struct btrfs_device, dev_list);
                if (device->bdev) {
                        close_bdev_excl(device->bdev);
-                       printk("close devices closes %s\n", device->name);
+                       fs_devices->open_devices--;
                }
                device->bdev = NULL;
+               device->in_fs_metadata = 0;
        }
+       fs_devices->mounted = 0;
        mutex_unlock(&uuid_mutex);
        return 0;
 }
@@ -174,30 +315,77 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
        struct list_head *head = &fs_devices->devices;
        struct list_head *cur;
        struct btrfs_device *device;
-       int ret;
+       struct block_device *latest_bdev = NULL;
+       struct buffer_head *bh;
+       struct btrfs_super_block *disk_super;
+       u64 latest_devid = 0;
+       u64 latest_transid = 0;
+       u64 transid;
+       u64 devid;
+       int ret = 0;
 
        mutex_lock(&uuid_mutex);
+       if (fs_devices->mounted)
+               goto out;
+
        list_for_each(cur, head) {
                device = list_entry(cur, struct btrfs_device, dev_list);
+               if (device->bdev)
+                       continue;
+
+               if (!device->name)
+                       continue;
+
                bdev = open_bdev_excl(device->name, flags, holder);
 
                if (IS_ERR(bdev)) {
                        printk("open %s failed\n", device->name);
-                       ret = PTR_ERR(bdev);
-                       goto fail;
+                       goto error;
                }
-               if (device->devid == fs_devices->latest_devid)
-                       fs_devices->latest_bdev = bdev;
-               if (device->devid == fs_devices->lowest_devid) {
-                       fs_devices->lowest_bdev = bdev;
+               set_blocksize(bdev, 4096);
+
+               bh = __bread(bdev, BTRFS_SUPER_INFO_OFFSET / 4096, 4096);
+               if (!bh)
+                       goto error_close;
+
+               disk_super = (struct btrfs_super_block *)bh->b_data;
+               if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
+                   sizeof(disk_super->magic)))
+                       goto error_brelse;
+
+               devid = le64_to_cpu(disk_super->dev_item.devid);
+               if (devid != device->devid)
+                       goto error_brelse;
+
+               transid = btrfs_super_generation(disk_super);
+               if (!latest_transid || transid > latest_transid) {
+                       latest_devid = devid;
+                       latest_transid = transid;
+                       latest_bdev = bdev;
                }
+
                device->bdev = bdev;
+               device->in_fs_metadata = 0;
+               fs_devices->open_devices++;
+               continue;
+
+error_brelse:
+               brelse(bh);
+error_close:
+               close_bdev_excl(bdev);
+error:
+               continue;
        }
+       if (fs_devices->open_devices == 0) {
+               ret = -EIO;
+               goto out;
+       }
+       fs_devices->mounted = 1;
+       fs_devices->latest_bdev = latest_bdev;
+       fs_devices->latest_devid = latest_devid;
+       fs_devices->latest_trans = latest_transid;
+out:
        mutex_unlock(&uuid_mutex);
-       return 0;
-fail:
-       mutex_unlock(&uuid_mutex);
-       btrfs_close_devices(fs_devices);
        return ret;
 }
 
@@ -213,11 +401,9 @@ int btrfs_scan_one_device(const char *path, int flags, void *holder,
 
        mutex_lock(&uuid_mutex);
 
-       printk("scan one opens %s\n", path);
        bdev = open_bdev_excl(path, flags, holder);
 
        if (IS_ERR(bdev)) {
-               printk("open failed\n");
                ret = PTR_ERR(bdev);
                goto error;
        }
@@ -233,13 +419,20 @@ int btrfs_scan_one_device(const char *path, int flags, void *holder,
        disk_super = (struct btrfs_super_block *)bh->b_data;
        if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
            sizeof(disk_super->magic))) {
-               printk("no btrfs found on %s\n", path);
                ret = -EINVAL;
                goto error_brelse;
        }
        devid = le64_to_cpu(disk_super->dev_item.devid);
        transid = btrfs_super_generation(disk_super);
-       printk("found device %Lu transid %Lu on %s\n", devid, transid, path);
+       if (disk_super->label[0])
+               printk("device label %s ", disk_super->label);
+       else {
+               /* FIXME, make a readl uuid parser */
+               printk("device fsid %llx-%llx ",
+                      *(unsigned long long *)disk_super->fsid,
+                      *(unsigned long long *)(disk_super->fsid + 8));
+       }
+       printk("devid %Lu transid %Lu %s\n", devid, transid, path);
        ret = device_list_add(path, disk_super, devid, fs_devices_ret);
 
 error_brelse:
@@ -282,6 +475,10 @@ static int find_free_dev_extent(struct btrfs_trans_handle *trans,
         * so we make sure to start at an offset of at least 1MB
         */
        search_start = max((u64)1024 * 1024, search_start);
+
+       if (root->fs_info->alloc_start + num_bytes <= device->total_bytes)
+               search_start = max(root->fs_info->alloc_start, search_start);
+
        key.objectid = device->devid;
        key.offset = search_start;
        key.type = BTRFS_DEV_EXTENT_KEY;
@@ -369,6 +566,54 @@ error:
        return ret;
 }
 
+int btrfs_free_dev_extent(struct btrfs_trans_handle *trans,
+                         struct btrfs_device *device,
+                         u64 start)
+{
+       int ret;
+       struct btrfs_path *path;
+       struct btrfs_root *root = device->dev_root;
+       struct btrfs_key key;
+       struct btrfs_key found_key;
+       struct extent_buffer *leaf = NULL;
+       struct btrfs_dev_extent *extent = NULL;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       key.objectid = device->devid;
+       key.offset = start;
+       key.type = BTRFS_DEV_EXTENT_KEY;
+
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+       if (ret > 0) {
+               ret = btrfs_previous_item(root, path, key.objectid,
+                                         BTRFS_DEV_EXTENT_KEY);
+               BUG_ON(ret);
+               leaf = path->nodes[0];
+               btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+               extent = btrfs_item_ptr(leaf, path->slots[0],
+                                       struct btrfs_dev_extent);
+               BUG_ON(found_key.offset > start || found_key.offset +
+                      btrfs_dev_extent_length(leaf, extent) < start);
+               ret = 0;
+       } else if (ret == 0) {
+               leaf = path->nodes[0];
+               extent = btrfs_item_ptr(leaf, path->slots[0],
+                                       struct btrfs_dev_extent);
+       }
+       BUG_ON(ret);
+
+       if (device->bytes_used > 0)
+               device->bytes_used -= btrfs_dev_extent_length(leaf, extent);
+       ret = btrfs_del_item(trans, root, path);
+       BUG_ON(ret);
+
+       btrfs_free_path(path);
+       return ret;
+}
+
 int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
                           struct btrfs_device *device,
                           u64 chunk_tree, u64 chunk_objectid,
@@ -382,6 +627,7 @@ int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
        struct extent_buffer *leaf;
        struct btrfs_key key;
 
+       WARN_ON(!device->in_fs_metadata);
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
@@ -491,106 +737,736 @@ error:
 }
 
 /*
- * the device information is stored in the chunk root
- * the btrfs_device struct should be fully filled in
+ * the device information is stored in the chunk root
+ * the btrfs_device struct should be fully filled in
+ */
+int btrfs_add_device(struct btrfs_trans_handle *trans,
+                    struct btrfs_root *root,
+                    struct btrfs_device *device)
+{
+       int ret;
+       struct btrfs_path *path;
+       struct btrfs_dev_item *dev_item;
+       struct extent_buffer *leaf;
+       struct btrfs_key key;
+       unsigned long ptr;
+       u64 free_devid = 0;
+
+       root = root->fs_info->chunk_root;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       ret = find_next_devid(root, path, &free_devid);
+       if (ret)
+               goto out;
+
+       key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
+       key.type = BTRFS_DEV_ITEM_KEY;
+       key.offset = free_devid;
+
+       ret = btrfs_insert_empty_item(trans, root, path, &key,
+                                     sizeof(*dev_item));
+       if (ret)
+               goto out;
+
+       leaf = path->nodes[0];
+       dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
+
+       device->devid = free_devid;
+       btrfs_set_device_id(leaf, dev_item, device->devid);
+       btrfs_set_device_type(leaf, dev_item, device->type);
+       btrfs_set_device_io_align(leaf, dev_item, device->io_align);
+       btrfs_set_device_io_width(leaf, dev_item, device->io_width);
+       btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
+       btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
+       btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
+       btrfs_set_device_group(leaf, dev_item, 0);
+       btrfs_set_device_seek_speed(leaf, dev_item, 0);
+       btrfs_set_device_bandwidth(leaf, dev_item, 0);
+
+       ptr = (unsigned long)btrfs_device_uuid(dev_item);
+       write_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
+       btrfs_mark_buffer_dirty(leaf);
+       ret = 0;
+
+out:
+       btrfs_free_path(path);
+       return ret;
+}
+
+static int btrfs_rm_dev_item(struct btrfs_root *root,
+                            struct btrfs_device *device)
+{
+       int ret;
+       struct btrfs_path *path;
+       struct block_device *bdev = device->bdev;
+       struct btrfs_device *next_dev;
+       struct btrfs_key key;
+       u64 total_bytes;
+       struct btrfs_fs_devices *fs_devices;
+       struct btrfs_trans_handle *trans;
+
+       root = root->fs_info->chunk_root;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       trans = btrfs_start_transaction(root, 1);
+       key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
+       key.type = BTRFS_DEV_ITEM_KEY;
+       key.offset = device->devid;
+
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+       if (ret < 0)
+               goto out;
+
+       if (ret > 0) {
+               ret = -ENOENT;
+               goto out;
+       }
+
+       ret = btrfs_del_item(trans, root, path);
+       if (ret)
+               goto out;
+
+       /*
+        * at this point, the device is zero sized.  We want to
+        * remove it from the devices list and zero out the old super
+        */
+       list_del_init(&device->dev_list);
+       list_del_init(&device->dev_alloc_list);
+       fs_devices = root->fs_info->fs_devices;
+
+       next_dev = list_entry(fs_devices->devices.next, struct btrfs_device,
+                             dev_list);
+       if (bdev == root->fs_info->sb->s_bdev)
+               root->fs_info->sb->s_bdev = next_dev->bdev;
+       if (bdev == fs_devices->latest_bdev)
+               fs_devices->latest_bdev = next_dev->bdev;
+
+       total_bytes = btrfs_super_num_devices(&root->fs_info->super_copy);
+       btrfs_set_super_num_devices(&root->fs_info->super_copy,
+                                   total_bytes - 1);
+out:
+       btrfs_free_path(path);
+       btrfs_commit_transaction(trans, root);
+       return ret;
+}
+
+int btrfs_rm_device(struct btrfs_root *root, char *device_path)
+{
+       struct btrfs_device *device;
+       struct block_device *bdev;
+       struct buffer_head *bh = NULL;
+       struct btrfs_super_block *disk_super;
+       u64 all_avail;
+       u64 devid;
+       int ret = 0;
+
+       mutex_lock(&root->fs_info->alloc_mutex);
+       mutex_lock(&root->fs_info->chunk_mutex);
+       mutex_lock(&uuid_mutex);
+
+       all_avail = root->fs_info->avail_data_alloc_bits |
+               root->fs_info->avail_system_alloc_bits |
+               root->fs_info->avail_metadata_alloc_bits;
+
+       if ((all_avail & BTRFS_BLOCK_GROUP_RAID10) &&
+           btrfs_super_num_devices(&root->fs_info->super_copy) <= 4) {
+               printk("btrfs: unable to go below four devices on raid10\n");
+               ret = -EINVAL;
+               goto out;
+       }
+
+       if ((all_avail & BTRFS_BLOCK_GROUP_RAID1) &&
+           btrfs_super_num_devices(&root->fs_info->super_copy) <= 2) {
+               printk("btrfs: unable to go below two devices on raid1\n");
+               ret = -EINVAL;
+               goto out;
+       }
+
+       if (strcmp(device_path, "missing") == 0) {
+               struct list_head *cur;
+               struct list_head *devices;
+               struct btrfs_device *tmp;
+
+               device = NULL;
+               devices = &root->fs_info->fs_devices->devices;
+               list_for_each(cur, devices) {
+                       tmp = list_entry(cur, struct btrfs_device, dev_list);
+                       if (tmp->in_fs_metadata && !tmp->bdev) {
+                               device = tmp;
+                               break;
+                       }
+               }
+               bdev = NULL;
+               bh = NULL;
+               disk_super = NULL;
+               if (!device) {
+                       printk("btrfs: no missing devices found to remove\n");
+                       goto out;
+               }
+
+       } else {
+               bdev = open_bdev_excl(device_path, 0,
+                                     root->fs_info->bdev_holder);
+               if (IS_ERR(bdev)) {
+                       ret = PTR_ERR(bdev);
+                       goto out;
+               }
+
+               bh = __bread(bdev, BTRFS_SUPER_INFO_OFFSET / 4096, 4096);
+               if (!bh) {
+                       ret = -EIO;
+                       goto error_close;
+               }
+               disk_super = (struct btrfs_super_block *)bh->b_data;
+               if (strncmp((char *)(&disk_super->magic), BTRFS_MAGIC,
+                   sizeof(disk_super->magic))) {
+                       ret = -ENOENT;
+                       goto error_brelse;
+               }
+               if (memcmp(disk_super->fsid, root->fs_info->fsid,
+                          BTRFS_FSID_SIZE)) {
+                       ret = -ENOENT;
+                       goto error_brelse;
+               }
+               devid = le64_to_cpu(disk_super->dev_item.devid);
+               device = btrfs_find_device(root, devid, NULL);
+               if (!device) {
+                       ret = -ENOENT;
+                       goto error_brelse;
+               }
+
+       }
+       root->fs_info->fs_devices->num_devices--;
+       root->fs_info->fs_devices->open_devices--;
+
+       ret = btrfs_shrink_device(device, 0);
+       if (ret)
+               goto error_brelse;
+
+
+       ret = btrfs_rm_dev_item(root->fs_info->chunk_root, device);
+       if (ret)
+               goto error_brelse;
+
+       if (bh) {
+               /* make sure this device isn't detected as part of
+                * the FS anymore
+                */
+               memset(&disk_super->magic, 0, sizeof(disk_super->magic));
+               set_buffer_dirty(bh);
+               sync_dirty_buffer(bh);
+
+               brelse(bh);
+       }
+
+       if (device->bdev) {
+               /* one close for the device struct or super_block */
+               close_bdev_excl(device->bdev);
+       }
+       if (bdev) {
+               /* one close for us */
+               close_bdev_excl(bdev);
+       }
+       kfree(device->name);
+       kfree(device);
+       ret = 0;
+       goto out;
+
+error_brelse:
+       brelse(bh);
+error_close:
+       if (bdev)
+               close_bdev_excl(bdev);
+out:
+       mutex_unlock(&uuid_mutex);
+       mutex_unlock(&root->fs_info->chunk_mutex);
+       mutex_unlock(&root->fs_info->alloc_mutex);
+       return ret;
+}
+
+int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
+{
+       struct btrfs_trans_handle *trans;
+       struct btrfs_device *device;
+       struct block_device *bdev;
+       struct list_head *cur;
+       struct list_head *devices;
+       u64 total_bytes;
+       int ret = 0;
+
+
+       bdev = open_bdev_excl(device_path, 0, root->fs_info->bdev_holder);
+       if (!bdev) {
+               return -EIO;
+       }
+
+       mutex_lock(&root->fs_info->alloc_mutex);
+       mutex_lock(&root->fs_info->chunk_mutex);
+
+       trans = btrfs_start_transaction(root, 1);
+       devices = &root->fs_info->fs_devices->devices;
+       list_for_each(cur, devices) {
+               device = list_entry(cur, struct btrfs_device, dev_list);
+               if (device->bdev == bdev) {
+                       ret = -EEXIST;
+                       goto out;
+               }
+       }
+
+       device = kzalloc(sizeof(*device), GFP_NOFS);
+       if (!device) {
+               /* we can safely leave the fs_devices entry around */
+               ret = -ENOMEM;
+               goto out_close_bdev;
+       }
+
+       device->barriers = 1;
+       device->work.func = pending_bios_fn;
+       generate_random_uuid(device->uuid);
+       spin_lock_init(&device->io_lock);
+       device->name = kstrdup(device_path, GFP_NOFS);
+       if (!device->name) {
+               kfree(device);
+               goto out_close_bdev;
+       }
+       device->io_width = root->sectorsize;
+       device->io_align = root->sectorsize;
+       device->sector_size = root->sectorsize;
+       device->total_bytes = i_size_read(bdev->bd_inode);
+       device->dev_root = root->fs_info->dev_root;
+       device->bdev = bdev;
+       device->in_fs_metadata = 1;
+
+       ret = btrfs_add_device(trans, root, device);
+       if (ret)
+               goto out_close_bdev;
+
+       total_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
+       btrfs_set_super_total_bytes(&root->fs_info->super_copy,
+                                   total_bytes + device->total_bytes);
+
+       total_bytes = btrfs_super_num_devices(&root->fs_info->super_copy);
+       btrfs_set_super_num_devices(&root->fs_info->super_copy,
+                                   total_bytes + 1);
+
+       list_add(&device->dev_list, &root->fs_info->fs_devices->devices);
+       list_add(&device->dev_alloc_list,
+                &root->fs_info->fs_devices->alloc_list);
+       root->fs_info->fs_devices->num_devices++;
+       root->fs_info->fs_devices->open_devices++;
+out:
+       btrfs_end_transaction(trans, root);
+       mutex_unlock(&root->fs_info->chunk_mutex);
+       mutex_unlock(&root->fs_info->alloc_mutex);
+
+       return ret;
+
+out_close_bdev:
+       close_bdev_excl(bdev);
+       goto out;
+}
+
+int btrfs_update_device(struct btrfs_trans_handle *trans,
+                       struct btrfs_device *device)
+{
+       int ret;
+       struct btrfs_path *path;
+       struct btrfs_root *root;
+       struct btrfs_dev_item *dev_item;
+       struct extent_buffer *leaf;
+       struct btrfs_key key;
+
+       root = device->dev_root->fs_info->chunk_root;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
+       key.type = BTRFS_DEV_ITEM_KEY;
+       key.offset = device->devid;
+
+       ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
+       if (ret < 0)
+               goto out;
+
+       if (ret > 0) {
+               ret = -ENOENT;
+               goto out;
+       }
+
+       leaf = path->nodes[0];
+       dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
+
+       btrfs_set_device_id(leaf, dev_item, device->devid);
+       btrfs_set_device_type(leaf, dev_item, device->type);
+       btrfs_set_device_io_align(leaf, dev_item, device->io_align);
+       btrfs_set_device_io_width(leaf, dev_item, device->io_width);
+       btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
+       btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
+       btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
+       btrfs_mark_buffer_dirty(leaf);
+
+out:
+       btrfs_free_path(path);
+       return ret;
+}
+
+int btrfs_grow_device(struct btrfs_trans_handle *trans,
+                     struct btrfs_device *device, u64 new_size)
+{
+       struct btrfs_super_block *super_copy =
+               &device->dev_root->fs_info->super_copy;
+       u64 old_total = btrfs_super_total_bytes(super_copy);
+       u64 diff = new_size - device->total_bytes;
+
+       btrfs_set_super_total_bytes(super_copy, old_total + diff);
+       return btrfs_update_device(trans, device);
+}
+
+static int btrfs_free_chunk(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root,
+                           u64 chunk_tree, u64 chunk_objectid,
+                           u64 chunk_offset)
+{
+       int ret;
+       struct btrfs_path *path;
+       struct btrfs_key key;
+
+       root = root->fs_info->chunk_root;
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       key.objectid = chunk_objectid;
+       key.offset = chunk_offset;
+       key.type = BTRFS_CHUNK_ITEM_KEY;
+
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+       BUG_ON(ret);
+
+       ret = btrfs_del_item(trans, root, path);
+       BUG_ON(ret);
+
+       btrfs_free_path(path);
+       return 0;
+}
+
+int btrfs_del_sys_chunk(struct btrfs_root *root, u64 chunk_objectid, u64
+                       chunk_offset)
+{
+       struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
+       struct btrfs_disk_key *disk_key;
+       struct btrfs_chunk *chunk;
+       u8 *ptr;
+       int ret = 0;
+       u32 num_stripes;
+       u32 array_size;
+       u32 len = 0;
+       u32 cur;
+       struct btrfs_key key;
+
+       array_size = btrfs_super_sys_array_size(super_copy);
+
+       ptr = super_copy->sys_chunk_array;
+       cur = 0;
+
+       while (cur < array_size) {
+               disk_key = (struct btrfs_disk_key *)ptr;
+               btrfs_disk_key_to_cpu(&key, disk_key);
+
+               len = sizeof(*disk_key);
+
+               if (key.type == BTRFS_CHUNK_ITEM_KEY) {
+                       chunk = (struct btrfs_chunk *)(ptr + len);
+                       num_stripes = btrfs_stack_chunk_num_stripes(chunk);
+                       len += btrfs_chunk_item_size(num_stripes);
+               } else {
+                       ret = -EIO;
+                       break;
+               }
+               if (key.objectid == chunk_objectid &&
+                   key.offset == chunk_offset) {
+                       memmove(ptr, ptr + len, array_size - (cur + len));
+                       array_size -= len;
+                       btrfs_set_super_sys_array_size(super_copy, array_size);
+               } else {
+                       ptr += len;
+                       cur += len;
+               }
+       }
+       return ret;
+}
+
+
+int btrfs_relocate_chunk(struct btrfs_root *root,
+                        u64 chunk_tree, u64 chunk_objectid,
+                        u64 chunk_offset)
+{
+       struct extent_map_tree *em_tree;
+       struct btrfs_root *extent_root;
+       struct btrfs_trans_handle *trans;
+       struct extent_map *em;
+       struct map_lookup *map;
+       int ret;
+       int i;
+
+       printk("btrfs relocating chunk %llu\n",
+              (unsigned long long)chunk_offset);
+       root = root->fs_info->chunk_root;
+       extent_root = root->fs_info->extent_root;
+       em_tree = &root->fs_info->mapping_tree.map_tree;
+
+       /* step one, relocate all the extents inside this chunk */
+       ret = btrfs_shrink_extent_tree(extent_root, chunk_offset);
+       BUG_ON(ret);
+
+       trans = btrfs_start_transaction(root, 1);
+       BUG_ON(!trans);
+
+       /*
+        * step two, delete the device extents and the
+        * chunk tree entries
+        */
+       spin_lock(&em_tree->lock);
+       em = lookup_extent_mapping(em_tree, chunk_offset, 1);
+       spin_unlock(&em_tree->lock);
+
+       BUG_ON(em->start > chunk_offset ||
+              em->start + em->len < chunk_offset);
+       map = (struct map_lookup *)em->bdev;
+
+       for (i = 0; i < map->num_stripes; i++) {
+               ret = btrfs_free_dev_extent(trans, map->stripes[i].dev,
+                                           map->stripes[i].physical);
+               BUG_ON(ret);
+
+               if (map->stripes[i].dev) {
+                       ret = btrfs_update_device(trans, map->stripes[i].dev);
+                       BUG_ON(ret);
+               }
+       }
+       ret = btrfs_free_chunk(trans, root, chunk_tree, chunk_objectid,
+                              chunk_offset);
+
+       BUG_ON(ret);
+
+       if (map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
+               ret = btrfs_del_sys_chunk(root, chunk_objectid, chunk_offset);
+               BUG_ON(ret);
+       }
+
+       spin_lock(&em_tree->lock);
+       remove_extent_mapping(em_tree, em);
+       kfree(map);
+       em->bdev = NULL;
+
+       /* once for the tree */
+       free_extent_map(em);
+       spin_unlock(&em_tree->lock);
+
+       /* once for us */
+       free_extent_map(em);
+
+       btrfs_end_transaction(trans, root);
+       return 0;
+}
+
+static u64 div_factor(u64 num, int factor)
+{
+       if (factor == 10)
+               return num;
+       num *= factor;
+       do_div(num, 10);
+       return num;
+}
+
+
+int btrfs_balance(struct btrfs_root *dev_root)
+{
+       int ret;
+       struct list_head *cur;
+       struct list_head *devices = &dev_root->fs_info->fs_devices->devices;
+       struct btrfs_device *device;
+       u64 old_size;
+       u64 size_to_free;
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       struct btrfs_chunk *chunk;
+       struct btrfs_root *chunk_root = dev_root->fs_info->chunk_root;
+       struct btrfs_trans_handle *trans;
+       struct btrfs_key found_key;
+
+
+       BUG(); /* FIXME, needs locking */
+
+       dev_root = dev_root->fs_info->dev_root;
+
+       /* step one make some room on all the devices */
+       list_for_each(cur, devices) {
+               device = list_entry(cur, struct btrfs_device, dev_list);
+               old_size = device->total_bytes;
+               size_to_free = div_factor(old_size, 1);
+               size_to_free = min(size_to_free, (u64)1 * 1024 * 1024);
+               if (device->total_bytes - device->bytes_used > size_to_free)
+                       continue;
+
+               ret = btrfs_shrink_device(device, old_size - size_to_free);
+               BUG_ON(ret);
+
+               trans = btrfs_start_transaction(dev_root, 1);
+               BUG_ON(!trans);
+
+               ret = btrfs_grow_device(trans, device, old_size);
+               BUG_ON(ret);
+
+               btrfs_end_transaction(trans, dev_root);
+       }
+
+       /* step two, relocate all the chunks */
+       path = btrfs_alloc_path();
+       BUG_ON(!path);
+
+       key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+       key.offset = (u64)-1;
+       key.type = BTRFS_CHUNK_ITEM_KEY;
+
+       while(1) {
+               ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
+               if (ret < 0)
+                       goto error;
+
+               /*
+                * this shouldn't happen, it means the last relocate
+                * failed
+                */
+               if (ret == 0)
+                       break;
+
+               ret = btrfs_previous_item(chunk_root, path, 0,
+                                         BTRFS_CHUNK_ITEM_KEY);
+               if (ret) {
+                       break;
+               }
+               btrfs_item_key_to_cpu(path->nodes[0], &found_key,
+                                     path->slots[0]);
+               if (found_key.objectid != key.objectid)
+                       break;
+               chunk = btrfs_item_ptr(path->nodes[0],
+                                      path->slots[0],
+                                      struct btrfs_chunk);
+               key.offset = found_key.offset;
+               /* chunk zero is special */
+               if (key.offset == 0)
+                       break;
+
+               ret = btrfs_relocate_chunk(chunk_root,
+                                          chunk_root->root_key.objectid,
+                                          found_key.objectid,
+                                          found_key.offset);
+               BUG_ON(ret);
+               btrfs_release_path(chunk_root, path);
+       }
+       ret = 0;
+error:
+       btrfs_free_path(path);
+       return ret;
+}
+
+/*
+ * shrinking a device means finding all of the device extents past
+ * the new size, and then following the back refs to the chunks.
+ * The chunk relocation code actually frees the device extent
  */
-int btrfs_add_device(struct btrfs_trans_handle *trans,
-                    struct btrfs_root *root,
-                    struct btrfs_device *device)
+int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 {
-       int ret;
+       struct btrfs_trans_handle *trans;
+       struct btrfs_root *root = device->dev_root;
+       struct btrfs_dev_extent *dev_extent = NULL;
        struct btrfs_path *path;
-       struct btrfs_dev_item *dev_item;
-       struct extent_buffer *leaf;
+       u64 length;
+       u64 chunk_tree;
+       u64 chunk_objectid;
+       u64 chunk_offset;
+       int ret;
+       int slot;
+       struct extent_buffer *l;
        struct btrfs_key key;
-       unsigned long ptr;
-       u64 free_devid;
+       struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
+       u64 old_total = btrfs_super_total_bytes(super_copy);
+       u64 diff = device->total_bytes - new_size;
 
-       root = root->fs_info->chunk_root;
 
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
 
-       ret = find_next_devid(root, path, &free_devid);
-       if (ret)
-               goto out;
-
-       key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
-       key.type = BTRFS_DEV_ITEM_KEY;
-       key.offset = free_devid;
+       trans = btrfs_start_transaction(root, 1);
+       if (!trans) {
+               ret = -ENOMEM;
+               goto done;
+       }
 
-       ret = btrfs_insert_empty_item(trans, root, path, &key,
-                                     sizeof(*dev_item));
-       if (ret)
-               goto out;
+       path->reada = 2;
 
-       leaf = path->nodes[0];
-       dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
+       device->total_bytes = new_size;
+       ret = btrfs_update_device(trans, device);
+       if (ret) {
+               btrfs_end_transaction(trans, root);
+               goto done;
+       }
+       WARN_ON(diff > old_total);
+       btrfs_set_super_total_bytes(super_copy, old_total - diff);
+       btrfs_end_transaction(trans, root);
 
-       device->devid = free_devid;
-       btrfs_set_device_id(leaf, dev_item, device->devid);
-       btrfs_set_device_type(leaf, dev_item, device->type);
-       btrfs_set_device_io_align(leaf, dev_item, device->io_align);
-       btrfs_set_device_io_width(leaf, dev_item, device->io_width);
-       btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
-       btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
-       btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
-       btrfs_set_device_group(leaf, dev_item, 0);
-       btrfs_set_device_seek_speed(leaf, dev_item, 0);
-       btrfs_set_device_bandwidth(leaf, dev_item, 0);
+       key.objectid = device->devid;
+       key.offset = (u64)-1;
+       key.type = BTRFS_DEV_EXTENT_KEY;
 
-       ptr = (unsigned long)btrfs_device_uuid(dev_item);
-       write_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
-       btrfs_mark_buffer_dirty(leaf);
-       ret = 0;
+       while (1) {
+               ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+               if (ret < 0)
+                       goto done;
+
+               ret = btrfs_previous_item(root, path, 0, key.type);
+               if (ret < 0)
+                       goto done;
+               if (ret) {
+                       ret = 0;
+                       goto done;
+               }
 
-out:
-       btrfs_free_path(path);
-       return ret;
-}
-int btrfs_update_device(struct btrfs_trans_handle *trans,
-                       struct btrfs_device *device)
-{
-       int ret;
-       struct btrfs_path *path;
-       struct btrfs_root *root;
-       struct btrfs_dev_item *dev_item;
-       struct extent_buffer *leaf;
-       struct btrfs_key key;
+               l = path->nodes[0];
+               slot = path->slots[0];
+               btrfs_item_key_to_cpu(l, &key, path->slots[0]);
 
-       root = device->dev_root->fs_info->chunk_root;
+               if (key.objectid != device->devid)
+                       goto done;
 
-       path = btrfs_alloc_path();
-       if (!path)
-               return -ENOMEM;
+               dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
+               length = btrfs_dev_extent_length(l, dev_extent);
 
-       key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
-       key.type = BTRFS_DEV_ITEM_KEY;
-       key.offset = device->devid;
+               if (key.offset + length <= new_size)
+                       goto done;
 
-       ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
-       if (ret < 0)
-               goto out;
+               chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
+               chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
+               chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
+               btrfs_release_path(root, path);
 
-       if (ret > 0) {
-               ret = -ENOENT;
-               goto out;
+               ret = btrfs_relocate_chunk(root, chunk_tree, chunk_objectid,
+                                          chunk_offset);
+               if (ret)
+                       goto done;
        }
 
-       leaf = path->nodes[0];
-       dev_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_item);
-
-       btrfs_set_device_id(leaf, dev_item, device->devid);
-       btrfs_set_device_type(leaf, dev_item, device->type);
-       btrfs_set_device_io_align(leaf, dev_item, device->io_align);
-       btrfs_set_device_io_width(leaf, dev_item, device->io_width);
-       btrfs_set_device_sector_size(leaf, dev_item, device->sector_size);
-       btrfs_set_device_total_bytes(leaf, dev_item, device->total_bytes);
-       btrfs_set_device_bytes_used(leaf, dev_item, device->bytes_used);
-       btrfs_mark_buffer_dirty(leaf);
-
-out:
+done:
        btrfs_free_path(path);
        return ret;
 }
@@ -619,6 +1495,18 @@ int btrfs_add_system_chunk(struct btrfs_trans_handle *trans,
        return 0;
 }
 
+static u64 chunk_bytes_by_type(u64 type, u64 calc_size, int num_stripes,
+                              int sub_stripes)
+{
+       if (type & (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP))
+               return calc_size;
+       else if (type & BTRFS_BLOCK_GROUP_RAID10)
+               return calc_size * (num_stripes / sub_stripes);
+       else
+               return calc_size * num_stripes;
+}
+
+
 int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                      struct btrfs_root *extent_root, u64 *start,
                      u64 *num_bytes, u64 type)
@@ -626,116 +1514,202 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        u64 dev_offset;
        struct btrfs_fs_info *info = extent_root->fs_info;
        struct btrfs_root *chunk_root = extent_root->fs_info->chunk_root;
+       struct btrfs_path *path;
        struct btrfs_stripe *stripes;
        struct btrfs_device *device = NULL;
        struct btrfs_chunk *chunk;
        struct list_head private_devs;
-       struct list_head *dev_list = &extent_root->fs_info->fs_devices->devices;
+       struct list_head *dev_list;
        struct list_head *cur;
        struct extent_map_tree *em_tree;
        struct map_lookup *map;
        struct extent_map *em;
+       int min_stripe_size = 1 * 1024 * 1024;
        u64 physical;
        u64 calc_size = 1024 * 1024 * 1024;
-       u64 min_free = calc_size;
+       u64 max_chunk_size = calc_size;
+       u64 min_free;
        u64 avail;
        u64 max_avail = 0;
+       u64 percent_max;
        int num_stripes = 1;
+       int min_stripes = 1;
+       int sub_stripes = 0;
        int looped = 0;
        int ret;
        int index;
        int stripe_len = 64 * 1024;
        struct btrfs_key key;
 
+       if ((type & BTRFS_BLOCK_GROUP_RAID1) &&
+           (type & BTRFS_BLOCK_GROUP_DUP)) {
+               WARN_ON(1);
+               type &= ~BTRFS_BLOCK_GROUP_DUP;
+       }
+       dev_list = &extent_root->fs_info->fs_devices->alloc_list;
        if (list_empty(dev_list))
                return -ENOSPC;
 
-       if (type & (BTRFS_BLOCK_GROUP_RAID0))
-               num_stripes = btrfs_super_num_devices(&info->super_copy);
-       if (type & (BTRFS_BLOCK_GROUP_DUP))
+       if (type & (BTRFS_BLOCK_GROUP_RAID0)) {
+               num_stripes = extent_root->fs_info->fs_devices->open_devices;
+               min_stripes = 2;
+       }
+       if (type & (BTRFS_BLOCK_GROUP_DUP)) {
                num_stripes = 2;
+               min_stripes = 2;
+       }
        if (type & (BTRFS_BLOCK_GROUP_RAID1)) {
                num_stripes = min_t(u64, 2,
-                                 btrfs_super_num_devices(&info->super_copy));
+                           extent_root->fs_info->fs_devices->open_devices);
+               if (num_stripes < 2)
+                       return -ENOSPC;
+               min_stripes = 2;
        }
+       if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
+               num_stripes = extent_root->fs_info->fs_devices->open_devices;
+               if (num_stripes < 4)
+                       return -ENOSPC;
+               num_stripes &= ~(u32)1;
+               sub_stripes = 2;
+               min_stripes = 4;
+       }
+
+       if (type & BTRFS_BLOCK_GROUP_DATA) {
+               max_chunk_size = 10 * calc_size;
+               min_stripe_size = 64 * 1024 * 1024;
+       } else if (type & BTRFS_BLOCK_GROUP_METADATA) {
+               max_chunk_size = 4 * calc_size;
+               min_stripe_size = 32 * 1024 * 1024;
+       } else if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
+               calc_size = 8 * 1024 * 1024;
+               max_chunk_size = calc_size * 2;
+               min_stripe_size = 1 * 1024 * 1024;
+       }
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       /* we don't want a chunk larger than 10% of the FS */
+       percent_max = div_factor(btrfs_super_total_bytes(&info->super_copy), 1);
+       max_chunk_size = min(percent_max, max_chunk_size);
+
 again:
+       if (calc_size * num_stripes > max_chunk_size) {
+               calc_size = max_chunk_size;
+               do_div(calc_size, num_stripes);
+               do_div(calc_size, stripe_len);
+               calc_size *= stripe_len;
+       }
+       /* we don't want tiny stripes */
+       calc_size = max_t(u64, min_stripe_size, calc_size);
+
+       do_div(calc_size, stripe_len);
+       calc_size *= stripe_len;
+
        INIT_LIST_HEAD(&private_devs);
        cur = dev_list->next;
        index = 0;
 
        if (type & BTRFS_BLOCK_GROUP_DUP)
                min_free = calc_size * 2;
+       else
+               min_free = calc_size;
+
+       /* we add 1MB because we never use the first 1MB of the device */
+       min_free += 1024 * 1024;
 
        /* build a private list of devices we will allocate from */
        while(index < num_stripes) {
-               device = list_entry(cur, struct btrfs_device, dev_list);
+               device = list_entry(cur, struct btrfs_device, dev_alloc_list);
 
-               avail = device->total_bytes - device->bytes_used;
+               if (device->total_bytes > device->bytes_used)
+                       avail = device->total_bytes - device->bytes_used;
+               else
+                       avail = 0;
                cur = cur->next;
-               if (avail > max_avail)
-                       max_avail = avail;
-               if (avail >= min_free) {
-                       list_move_tail(&device->dev_list, &private_devs);
-                       index++;
-                       if (type & BTRFS_BLOCK_GROUP_DUP)
+
+               if (device->in_fs_metadata && avail >= min_free) {
+                       u64 ignored_start = 0;
+                       ret = find_free_dev_extent(trans, device, path,
+                                                  min_free,
+                                                  &ignored_start);
+                       if (ret == 0) {
+                               list_move_tail(&device->dev_alloc_list,
+                                              &private_devs);
                                index++;
-               }
+                               if (type & BTRFS_BLOCK_GROUP_DUP)
+                                       index++;
+                       }
+               } else if (device->in_fs_metadata && avail > max_avail)
+                       max_avail = avail;
                if (cur == dev_list)
                        break;
        }
        if (index < num_stripes) {
                list_splice(&private_devs, dev_list);
+               if (index >= min_stripes) {
+                       num_stripes = index;
+                       if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
+                               num_stripes /= sub_stripes;
+                               num_stripes *= sub_stripes;
+                       }
+                       looped = 1;
+                       goto again;
+               }
                if (!looped && max_avail > 0) {
                        looped = 1;
                        calc_size = max_avail;
                        goto again;
                }
+               btrfs_free_path(path);
                return -ENOSPC;
        }
-
        key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
        key.type = BTRFS_CHUNK_ITEM_KEY;
        ret = find_next_chunk(chunk_root, BTRFS_FIRST_CHUNK_TREE_OBJECTID,
                              &key.offset);
-       if (ret)
+       if (ret) {
+               btrfs_free_path(path);
                return ret;
+       }
 
        chunk = kmalloc(btrfs_chunk_item_size(num_stripes), GFP_NOFS);
-       if (!chunk)
+       if (!chunk) {
+               btrfs_free_path(path);
                return -ENOMEM;
+       }
 
        map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
        if (!map) {
                kfree(chunk);
+               btrfs_free_path(path);
                return -ENOMEM;
        }
+       btrfs_free_path(path);
+       path = NULL;
 
        stripes = &chunk->stripe;
-
-       if (type & (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP))
-               *num_bytes = calc_size;
-       else
-               *num_bytes = calc_size * num_stripes;
+       *num_bytes = chunk_bytes_by_type(type, calc_size,
+                                        num_stripes, sub_stripes);
 
        index = 0;
-printk("new chunk type %Lu start %Lu size %Lu\n", type, key.offset, *num_bytes);
        while(index < num_stripes) {
                struct btrfs_stripe *stripe;
                BUG_ON(list_empty(&private_devs));
                cur = private_devs.next;
-               device = list_entry(cur, struct btrfs_device, dev_list);
+               device = list_entry(cur, struct btrfs_device, dev_alloc_list);
 
                /* loop over this device again if we're doing a dup group */
                if (!(type & BTRFS_BLOCK_GROUP_DUP) ||
                    (index == num_stripes - 1))
-                       list_move_tail(&device->dev_list, dev_list);
+                       list_move_tail(&device->dev_alloc_list, dev_list);
 
                ret = btrfs_alloc_dev_extent(trans, device,
                             info->chunk_root->root_key.objectid,
                             BTRFS_FIRST_CHUNK_TREE_OBJECTID, key.offset,
                             calc_size, &dev_offset);
                BUG_ON(ret);
-printk("alloc chunk start %Lu size %Lu from dev %Lu type %Lu\n", key.offset, calc_size, device->devid, type);
                device->bytes_used += calc_size;
                ret = btrfs_update_device(trans, device);
                BUG_ON(ret);
@@ -760,12 +1734,14 @@ printk("alloc chunk start %Lu size %Lu from dev %Lu type %Lu\n", key.offset, cal
        btrfs_set_stack_chunk_io_align(chunk, stripe_len);
        btrfs_set_stack_chunk_io_width(chunk, stripe_len);
        btrfs_set_stack_chunk_sector_size(chunk, extent_root->sectorsize);
+       btrfs_set_stack_chunk_sub_stripes(chunk, sub_stripes);
        map->sector_size = extent_root->sectorsize;
        map->stripe_len = stripe_len;
        map->io_align = stripe_len;
        map->io_width = stripe_len;
        map->type = type;
        map->num_stripes = num_stripes;
+       map->sub_stripes = sub_stripes;
 
        ret = btrfs_insert_item(trans, chunk_root, &key, chunk,
                                btrfs_chunk_item_size(num_stripes));
@@ -780,6 +1756,11 @@ printk("alloc chunk start %Lu size %Lu from dev %Lu type %Lu\n", key.offset, cal
        em->len = *num_bytes;
        em->block_start = 0;
 
+       if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
+               ret = btrfs_add_system_chunk(trans, chunk_root, &key,
+                                   chunk, btrfs_chunk_item_size(num_stripes));
+               BUG_ON(ret);
+       }
        kfree(chunk);
 
        em_tree = &extent_root->fs_info->mapping_tree.map_tree;
@@ -832,15 +1813,34 @@ int btrfs_num_copies(struct btrfs_mapping_tree *map_tree, u64 logical, u64 len)
        map = (struct map_lookup *)em->bdev;
        if (map->type & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1))
                ret = map->num_stripes;
+       else if (map->type & BTRFS_BLOCK_GROUP_RAID10)
+               ret = map->sub_stripes;
        else
                ret = 1;
        free_extent_map(em);
        return ret;
 }
 
-int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
-                   u64 logical, u64 *length,
-                   struct btrfs_multi_bio **multi_ret, int mirror_num)
+static int find_live_mirror(struct map_lookup *map, int first, int num,
+                           int optimal)
+{
+       int i;
+       if (map->stripes[optimal].dev->bdev)
+               return optimal;
+       for (i = first; i < first + num; i++) {
+               if (map->stripes[i].dev->bdev)
+                       return i;
+       }
+       /* we couldn't find one that doesn't fail.  Just return something
+        * and the io error handling code will clean up eventually
+        */
+       return optimal;
+}
+
+static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
+                            u64 logical, u64 *length,
+                            struct btrfs_multi_bio **multi_ret,
+                            int mirror_num, struct page *unplug_page)
 {
        struct extent_map *em;
        struct map_lookup *map;
@@ -849,8 +1849,11 @@ int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
        u64 stripe_offset;
        u64 stripe_nr;
        int stripes_allocated = 8;
+       int stripes_required = 1;
        int stripe_index;
        int i;
+       int num_stripes;
+       int max_errors = 0;
        struct btrfs_multi_bio *multi = NULL;
 
        if (multi_ret && !(rw & (1 << BIO_RW))) {
@@ -862,12 +1865,21 @@ again:
                                GFP_NOFS);
                if (!multi)
                        return -ENOMEM;
+
+               atomic_set(&multi->error, 0);
        }
 
        spin_lock(&em_tree->lock);
        em = lookup_extent_mapping(em_tree, logical, *length);
        spin_unlock(&em_tree->lock);
-       BUG_ON(!em);
+
+       if (!em && unplug_page)
+               return 0;
+
+       if (!em) {
+               printk("unable to find logical %Lu len %Lu\n", logical, *length);
+               BUG();
+       }
 
        BUG_ON(em->start > logical || em->start + em->len < logical);
        map = (struct map_lookup *)em->bdev;
@@ -877,10 +1889,18 @@ again:
                mirror_num = 0;
 
        /* if our multi bio struct is too small, back off and try again */
-       if (multi_ret && (rw & (1 << BIO_RW)) &&
-           stripes_allocated < map->num_stripes &&
-           ((map->type & BTRFS_BLOCK_GROUP_RAID1) ||
-            (map->type & BTRFS_BLOCK_GROUP_DUP))) {
+       if (rw & (1 << BIO_RW)) {
+               if (map->type & (BTRFS_BLOCK_GROUP_RAID1 |
+                                BTRFS_BLOCK_GROUP_DUP)) {
+                       stripes_required = map->num_stripes;
+                       max_errors = 1;
+               } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
+                       stripes_required = map->sub_stripes;
+                       max_errors = 1;
+               }
+       }
+       if (multi_ret && rw == WRITE &&
+           stripes_allocated < stripes_required) {
                stripes_allocated = map->num_stripes;
                free_extent_map(em);
                kfree(multi);
@@ -900,6 +1920,7 @@ again:
        stripe_offset = offset - stripe_offset;
 
        if (map->type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
+                        BTRFS_BLOCK_GROUP_RAID10 |
                         BTRFS_BLOCK_GROUP_DUP)) {
                /* we limit the length of each bio to what fits in a stripe */
                *length = min_t(u64, em->len - offset,
@@ -907,36 +1928,44 @@ again:
        } else {
                *length = em->len - offset;
        }
-       if (!multi_ret)
+
+       if (!multi_ret && !unplug_page)
                goto out;
 
-       multi->num_stripes = 1;
+       num_stripes = 1;
        stripe_index = 0;
        if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
-               if (rw & (1 << BIO_RW))
-                       multi->num_stripes = map->num_stripes;
-               else if (mirror_num) {
+               if (unplug_page || (rw & (1 << BIO_RW)))
+                       num_stripes = map->num_stripes;
+               else if (mirror_num)
                        stripe_index = mirror_num - 1;
-               } else {
-                       int i;
-                       u64 least = (u64)-1;
-                       struct btrfs_device *cur;
-
-                       for (i = 0; i < map->num_stripes; i++) {
-                               cur = map->stripes[i].dev;
-                               spin_lock(&cur->io_lock);
-                               if (cur->total_ios < least) {
-                                       least = cur->total_ios;
-                                       stripe_index = i;
-                               }
-                               spin_unlock(&cur->io_lock);
-                       }
+               else {
+                       stripe_index = find_live_mirror(map, 0,
+                                           map->num_stripes,
+                                           current->pid % map->num_stripes);
                }
+
        } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
                if (rw & (1 << BIO_RW))
-                       multi->num_stripes = map->num_stripes;
+                       num_stripes = map->num_stripes;
                else if (mirror_num)
                        stripe_index = mirror_num - 1;
+
+       } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
+               int factor = map->num_stripes / map->sub_stripes;
+
+               stripe_index = do_div(stripe_nr, factor);
+               stripe_index *= map->sub_stripes;
+
+               if (unplug_page || (rw & (1 << BIO_RW)))
+                       num_stripes = map->sub_stripes;
+               else if (mirror_num)
+                       stripe_index += mirror_num - 1;
+               else {
+                       stripe_index = find_live_mirror(map, stripe_index,
+                                             map->sub_stripes, stripe_index +
+                                             current->pid % map->sub_stripes);
+               }
        } else {
                /*
                 * after this do_div call, stripe_nr is the number of stripes
@@ -946,21 +1975,54 @@ again:
                stripe_index = do_div(stripe_nr, map->num_stripes);
        }
        BUG_ON(stripe_index >= map->num_stripes);
-       BUG_ON(stripe_index != 0 && multi->num_stripes > 1);
 
-       for (i = 0; i < multi->num_stripes; i++) {
-               multi->stripes[i].physical =
-                       map->stripes[stripe_index].physical + stripe_offset +
-                       stripe_nr * map->stripe_len;
-               multi->stripes[i].dev = map->stripes[stripe_index].dev;
+       for (i = 0; i < num_stripes; i++) {
+               if (unplug_page) {
+                       struct btrfs_device *device;
+                       struct backing_dev_info *bdi;
+
+                       device = map->stripes[stripe_index].dev;
+                       if (device->bdev) {
+                               bdi = blk_get_backing_dev_info(device->bdev);
+                               if (bdi->unplug_io_fn) {
+                                       bdi->unplug_io_fn(bdi, unplug_page);
+                               }
+                       }
+               } else {
+                       multi->stripes[i].physical =
+                               map->stripes[stripe_index].physical +
+                               stripe_offset + stripe_nr * map->stripe_len;
+                       multi->stripes[i].dev = map->stripes[stripe_index].dev;
+               }
                stripe_index++;
        }
-       *multi_ret = multi;
+       if (multi_ret) {
+               *multi_ret = multi;
+               multi->num_stripes = num_stripes;
+               multi->max_errors = max_errors;
+       }
 out:
        free_extent_map(em);
        return 0;
 }
 
+int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
+                     u64 logical, u64 *length,
+                     struct btrfs_multi_bio **multi_ret, int mirror_num)
+{
+       return __btrfs_map_block(map_tree, rw, logical, length, multi_ret,
+                                mirror_num, NULL);
+}
+
+int btrfs_unplug_page(struct btrfs_mapping_tree *map_tree,
+                     u64 logical, struct page *page)
+{
+       u64 length = PAGE_CACHE_SIZE;
+       return __btrfs_map_block(map_tree, READ, logical, &length,
+                                NULL, 0, page);
+}
+
+
 #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
 static void end_bio_multi_stripe(struct bio *bio, int err)
 #else
@@ -975,14 +2037,24 @@ static int end_bio_multi_stripe(struct bio *bio,
                return 1;
 #endif
        if (err)
-               multi->error = err;
+               atomic_inc(&multi->error);
 
        if (atomic_dec_and_test(&multi->stripes_pending)) {
                bio->bi_private = multi->private;
                bio->bi_end_io = multi->end_io;
-
-               if (!err && multi->error)
-                       err = multi->error;
+               /* only send an error to the higher layers if it is
+                * beyond the tolerance of the multi-bio
+                */
+               if (atomic_read(&multi->error) > multi->max_errors) {
+                       err = -EIO;
+               } else if (err) {
+                       /*
+                        * this bio is actually up to date, we didn't
+                        * go over the max number of errors
+                        */
+                       set_bit(BIO_UPTODATE, &bio->bi_flags);
+                       err = 0;
+               }
                kfree(multi);
 
 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
@@ -998,8 +2070,62 @@ static int end_bio_multi_stripe(struct bio *bio,
 #endif
 }
 
+struct async_sched {
+       struct bio *bio;
+       int rw;
+       struct btrfs_fs_info *info;
+       struct btrfs_work work;
+};
+
+/*
+ * see run_scheduled_bios for a description of why bios are collected for
+ * async submit.
+ *
+ * This will add one bio to the pending list for a device and make sure
+ * the work struct is scheduled.
+ */
+int schedule_bio(struct btrfs_root *root, struct btrfs_device *device,
+                int rw, struct bio *bio)
+{
+       int should_queue = 1;
+
+       /* don't bother with additional async steps for reads, right now */
+       if (!(rw & (1 << BIO_RW))) {
+               submit_bio(rw, bio);
+               return 0;
+       }
+
+       /*
+        * nr_async_sumbits allows us to reliably return congestion to the
+        * higher layers.  Otherwise, the async bio makes it appear we have
+        * made progress against dirty pages when we've really just put it
+        * on a queue for later
+        */
+       atomic_inc(&root->fs_info->nr_async_submits);
+       bio->bi_next = NULL;
+       bio->bi_rw |= rw;
+
+       spin_lock(&device->io_lock);
+
+       if (device->pending_bio_tail)
+               device->pending_bio_tail->bi_next = bio;
+
+       device->pending_bio_tail = bio;
+       if (!device->pending_bios)
+               device->pending_bios = bio;
+       if (device->running_pending)
+               should_queue = 0;
+
+       spin_unlock(&device->io_lock);
+
+       if (should_queue)
+               btrfs_queue_worker(&root->fs_info->submit_workers,
+                                  &device->work);
+       return 0;
+}
+
 int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
-                 int mirror_num)
+                 int mirror_num, int async_submit)
 {
        struct btrfs_mapping_tree *map_tree;
        struct btrfs_device *dev;
@@ -1007,17 +2133,12 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
        u64 logical = bio->bi_sector << 9;
        u64 length = 0;
        u64 map_length;
-       struct bio_vec *bvec;
        struct btrfs_multi_bio *multi = NULL;
-       int i;
        int ret;
        int dev_nr = 0;
        int total_devs = 1;
 
-       bio_for_each_segment(bvec, bio, i) {
-               length += bvec->bv_len;
-       }
-
+       length = bio->bi_size;
        map_tree = &root->fs_info->mapping_tree;
        map_length = length;
 
@@ -1048,11 +2169,21 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
                }
                bio->bi_sector = multi->stripes[dev_nr].physical >> 9;
                dev = multi->stripes[dev_nr].dev;
-               bio->bi_bdev = dev->bdev;
-               spin_lock(&dev->io_lock);
-               dev->total_ios++;
-               spin_unlock(&dev->io_lock);
-               submit_bio(rw, bio);
+               if (dev && dev->bdev) {
+                       bio->bi_bdev = dev->bdev;
+                       if (async_submit)
+                               schedule_bio(root, dev, rw, bio);
+                       else
+                               submit_bio(rw, bio);
+               } else {
+                       bio->bi_bdev = root->fs_info->fs_devices->latest_bdev;
+                       bio->bi_sector = logical >> 9;
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+                       bio_endio(bio, bio->bi_size, -EIO);
+#else
+                       bio_endio(bio, -EIO);
+#endif
+               }
                dev_nr++;
        }
        if (total_devs == 1)
@@ -1060,13 +2191,36 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
        return 0;
 }
 
-struct btrfs_device *btrfs_find_device(struct btrfs_root *root, u64 devid)
+struct btrfs_device *btrfs_find_device(struct btrfs_root *root, u64 devid,
+                                      u8 *uuid)
 {
        struct list_head *head = &root->fs_info->fs_devices->devices;
 
-       return __find_device(head, devid);
+       return __find_device(head, devid, uuid);
+}
+
+static struct btrfs_device *add_missing_dev(struct btrfs_root *root,
+                                           u64 devid, u8 *dev_uuid)
+{
+       struct btrfs_device *device;
+       struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
+
+       device = kzalloc(sizeof(*device), GFP_NOFS);
+       list_add(&device->dev_list,
+                &fs_devices->devices);
+       list_add(&device->dev_alloc_list,
+                &fs_devices->alloc_list);
+       device->barriers = 1;
+       device->dev_root = root->fs_info->dev_root;
+       device->devid = devid;
+       device->work.func = pending_bios_fn;
+       fs_devices->num_devices++;
+       spin_lock_init(&device->io_lock);
+       memcpy(device->uuid, dev_uuid, BTRFS_UUID_SIZE);
+       return device;
 }
 
+
 static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
                          struct extent_buffer *leaf,
                          struct btrfs_chunk *chunk)
@@ -1077,12 +2231,14 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
        u64 logical;
        u64 length;
        u64 devid;
+       u8 uuid[BTRFS_UUID_SIZE];
        int num_stripes;
        int ret;
        int i;
 
        logical = key->offset;
        length = btrfs_chunk_length(leaf, chunk);
+
        spin_lock(&map_tree->map_tree.lock);
        em = lookup_extent_mapping(&map_tree->map_tree, logical, 1);
        spin_unlock(&map_tree->map_tree.lock);
@@ -1120,16 +2276,31 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
        map->sector_size = btrfs_chunk_sector_size(leaf, chunk);
        map->stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
        map->type = btrfs_chunk_type(leaf, chunk);
+       map->sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk);
        for (i = 0; i < num_stripes; i++) {
                map->stripes[i].physical =
                        btrfs_stripe_offset_nr(leaf, chunk, i);
                devid = btrfs_stripe_devid_nr(leaf, chunk, i);
-               map->stripes[i].dev = btrfs_find_device(root, devid);
-               if (!map->stripes[i].dev) {
+               read_extent_buffer(leaf, uuid, (unsigned long)
+                                  btrfs_stripe_dev_uuid_nr(chunk, i),
+                                  BTRFS_UUID_SIZE);
+               map->stripes[i].dev = btrfs_find_device(root, devid, uuid);
+
+               if (!map->stripes[i].dev && !btrfs_test_opt(root, DEGRADED)) {
                        kfree(map);
                        free_extent_map(em);
                        return -EIO;
                }
+               if (!map->stripes[i].dev) {
+                       map->stripes[i].dev =
+                               add_missing_dev(root, devid, uuid);
+                       if (!map->stripes[i].dev) {
+                               kfree(map);
+                               free_extent_map(em);
+                               return -EIO;
+                       }
+               }
+               map->stripes[i].dev->in_fs_metadata = 1;
        }
 
        spin_lock(&map_tree->map_tree.lock);
@@ -1168,21 +2339,23 @@ static int read_one_dev(struct btrfs_root *root,
        struct btrfs_device *device;
        u64 devid;
        int ret;
+       u8 dev_uuid[BTRFS_UUID_SIZE];
+
        devid = btrfs_device_id(leaf, dev_item);
-       device = btrfs_find_device(root, devid);
+       read_extent_buffer(leaf, dev_uuid,
+                          (unsigned long)btrfs_device_uuid(dev_item),
+                          BTRFS_UUID_SIZE);
+       device = btrfs_find_device(root, devid, dev_uuid);
        if (!device) {
-               printk("warning devid %Lu not found already\n", devid);
-               device = kzalloc(sizeof(*device), GFP_NOFS);
+               printk("warning devid %Lu missing\n", devid);
+               device = add_missing_dev(root, devid, dev_uuid);
                if (!device)
                        return -ENOMEM;
-               list_add(&device->dev_list,
-                        &root->fs_info->fs_devices->devices);
-               device->barriers = 1;
-               spin_lock_init(&device->io_lock);
        }
 
        fill_device_from_item(leaf, dev_item, device);
        device->dev_root = root->fs_info->dev_root;
+       device->in_fs_metadata = 1;
        ret = 0;
 #if 0
        ret = btrfs_open_device(device);
@@ -1205,25 +2378,26 @@ int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf)
 int btrfs_read_sys_array(struct btrfs_root *root)
 {
        struct btrfs_super_block *super_copy = &root->fs_info->super_copy;
-       struct extent_buffer *sb = root->fs_info->sb_buffer;
+       struct extent_buffer *sb;
        struct btrfs_disk_key *disk_key;
        struct btrfs_chunk *chunk;
-       struct btrfs_key key;
+       u8 *ptr;
+       unsigned long sb_ptr;
+       int ret = 0;
        u32 num_stripes;
        u32 array_size;
        u32 len = 0;
-       u8 *ptr;
-       unsigned long sb_ptr;
        u32 cur;
-       int ret;
+       struct btrfs_key key;
 
+       sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET,
+                                         BTRFS_SUPER_INFO_SIZE);
+       if (!sb)
+               return -ENOMEM;
+       btrfs_set_buffer_uptodate(sb);
+       write_extent_buffer(sb, super_copy, 0, BTRFS_SUPER_INFO_SIZE);
        array_size = btrfs_super_sys_array_size(super_copy);
 
-       /*
-        * we do this loop twice, once for the device items and
-        * once for all of the chunks.  This way there are device
-        * structs filled in for every chunk
-        */
        ptr = super_copy->sys_chunk_array;
        sb_ptr = offsetof(struct btrfs_super_block, sys_chunk_array);
        cur = 0;
@@ -1232,25 +2406,27 @@ int btrfs_read_sys_array(struct btrfs_root *root)
                disk_key = (struct btrfs_disk_key *)ptr;
                btrfs_disk_key_to_cpu(&key, disk_key);
 
-               len = sizeof(*disk_key);
-               ptr += len;
+               len = sizeof(*disk_key); ptr += len;
                sb_ptr += len;
                cur += len;
 
                if (key.type == BTRFS_CHUNK_ITEM_KEY) {
                        chunk = (struct btrfs_chunk *)sb_ptr;
                        ret = read_one_chunk(root, &key, sb, chunk);
-                       BUG_ON(ret);
+                       if (ret)
+                               break;
                        num_stripes = btrfs_chunk_num_stripes(sb, chunk);
                        len = btrfs_chunk_item_size(num_stripes);
                } else {
-                       BUG();
+                       ret = -EIO;
+                       break;
                }
                ptr += len;
                sb_ptr += len;
                cur += len;
        }
-       return 0;
+       free_extent_buffer(sb);
+       return ret;
 }
 
 int btrfs_read_chunk_tree(struct btrfs_root *root)