Btrfs: introduce GET_READ_MIRRORS functionality for btrfs_map_block()
[cascardo/linux.git] / fs / btrfs / volumes.c
index 5612767..de0c05c 100644 (file)
@@ -36,6 +36,7 @@
 #include "check-integrity.h"
 #include "rcu-string.h"
 #include "math.h"
+#include "dev-replace.h"
 
 static int init_first_rw_device(struct btrfs_trans_handle *trans,
                                struct btrfs_root *root,
@@ -505,7 +506,8 @@ error:
        return ERR_PTR(-ENOMEM);
 }
 
-void btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices)
+void btrfs_close_extra_devices(struct btrfs_fs_info *fs_info,
+                              struct btrfs_fs_devices *fs_devices, int step)
 {
        struct btrfs_device *device, *next;
 
@@ -518,8 +520,9 @@ again:
        /* This is the initialized path, it is safe to release the devices. */
        list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
                if (device->in_fs_metadata) {
-                       if (!latest_transid ||
-                           device->generation > latest_transid) {
+                       if (!device->is_tgtdev_for_dev_replace &&
+                           (!latest_transid ||
+                            device->generation > latest_transid)) {
                                latest_devid = device->devid;
                                latest_transid = device->generation;
                                latest_bdev = device->bdev;
@@ -527,6 +530,21 @@ again:
                        continue;
                }
 
+               if (device->devid == BTRFS_DEV_REPLACE_DEVID) {
+                       /*
+                        * In the first step, keep the device which has
+                        * the correct fsid and the devid that is used
+                        * for the dev_replace procedure.
+                        * In the second step, the dev_replace state is
+                        * read from the device tree and it is known
+                        * whether the procedure is really active or
+                        * not, which means whether this device is
+                        * used or whether it should be removed.
+                        */
+                       if (step == 0 || device->is_tgtdev_for_dev_replace) {
+                               continue;
+                       }
+               }
                if (device->bdev) {
                        blkdev_put(device->bdev, device->mode);
                        device->bdev = NULL;
@@ -535,7 +553,8 @@ again:
                if (device->writeable) {
                        list_del_init(&device->dev_alloc_list);
                        device->writeable = 0;
-                       fs_devices->rw_devices--;
+                       if (!device->is_tgtdev_for_dev_replace)
+                               fs_devices->rw_devices--;
                }
                list_del_init(&device->dev_list);
                fs_devices->num_devices--;
@@ -593,7 +612,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
                if (device->bdev)
                        fs_devices->open_devices--;
 
-               if (device->writeable) {
+               if (device->writeable && !device->is_tgtdev_for_dev_replace) {
                        list_del_init(&device->dev_alloc_list);
                        fs_devices->rw_devices--;
                }
@@ -717,7 +736,7 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                        fs_devices->rotating = 1;
 
                fs_devices->open_devices++;
-               if (device->writeable) {
+               if (device->writeable && !device->is_tgtdev_for_dev_replace) {
                        fs_devices->rw_devices++;
                        list_add(&device->dev_alloc_list,
                                 &fs_devices->alloc_list);
@@ -814,7 +833,7 @@ int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
 
        *length = 0;
 
-       if (start >= device->total_bytes)
+       if (start >= device->total_bytes || device->is_tgtdev_for_dev_replace)
                return 0;
 
        path = btrfs_alloc_path();
@@ -931,7 +950,7 @@ int find_free_dev_extent(struct btrfs_device *device, u64 num_bytes,
        max_hole_size = 0;
        hole_size = 0;
 
-       if (search_start >= search_end) {
+       if (search_start >= search_end || device->is_tgtdev_for_dev_replace) {
                ret = -ENOSPC;
                goto error;
        }
@@ -1114,6 +1133,7 @@ int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
        struct btrfs_key key;
 
        WARN_ON(!device->in_fs_metadata);
+       WARN_ON(device->is_tgtdev_for_dev_replace);
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
@@ -1348,16 +1368,22 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                root->fs_info->avail_system_alloc_bits |
                root->fs_info->avail_metadata_alloc_bits;
 
-       if ((all_avail & BTRFS_BLOCK_GROUP_RAID10) &&
-           root->fs_info->fs_devices->num_devices <= 4) {
+       num_devices = root->fs_info->fs_devices->num_devices;
+       btrfs_dev_replace_lock(&root->fs_info->dev_replace);
+       if (btrfs_dev_replace_is_ongoing(&root->fs_info->dev_replace)) {
+               WARN_ON(num_devices < 1);
+               num_devices--;
+       }
+       btrfs_dev_replace_unlock(&root->fs_info->dev_replace);
+
+       if ((all_avail & BTRFS_BLOCK_GROUP_RAID10) && num_devices <= 4) {
                printk(KERN_ERR "btrfs: unable to go below four devices "
                       "on raid10\n");
                ret = -EINVAL;
                goto out;
        }
 
-       if ((all_avail & BTRFS_BLOCK_GROUP_RAID1) &&
-           root->fs_info->fs_devices->num_devices <= 2) {
+       if ((all_avail & BTRFS_BLOCK_GROUP_RAID1) && num_devices <= 2) {
                printk(KERN_ERR "btrfs: unable to go below two "
                       "devices on raid1\n");
                ret = -EINVAL;
@@ -1375,7 +1401,9 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                 * is held.
                 */
                list_for_each_entry(tmp, devices, dev_list) {
-                       if (tmp->in_fs_metadata && !tmp->bdev) {
+                       if (tmp->in_fs_metadata &&
+                           !tmp->is_tgtdev_for_dev_replace &&
+                           !tmp->bdev) {
                                device = tmp;
                                break;
                        }
@@ -1398,7 +1426,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                disk_super = (struct btrfs_super_block *)bh->b_data;
                devid = btrfs_stack_device_id(&disk_super->dev_item);
                dev_uuid = disk_super->dev_item.uuid;
-               device = btrfs_find_device(root, devid, dev_uuid,
+               device = btrfs_find_device(root->fs_info, devid, dev_uuid,
                                           disk_super->fsid);
                if (!device) {
                        ret = -ENOENT;
@@ -1406,6 +1434,12 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                }
        }
 
+       if (device->is_tgtdev_for_dev_replace) {
+               pr_err("btrfs: unable to remove the dev_replace target dev\n");
+               ret = -EINVAL;
+               goto error_brelse;
+       }
+
        if (device->writeable && root->fs_info->fs_devices->rw_devices == 1) {
                printk(KERN_ERR "btrfs: unable to remove the only writeable "
                       "device\n");
@@ -1425,6 +1459,11 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
        if (ret)
                goto error_undo;
 
+       /*
+        * TODO: the superblock still includes this device in its num_devices
+        * counter although write_all_supers() is not locked out. This
+        * could give a filesystem state which requires a degraded mount.
+        */
        ret = btrfs_rm_dev_item(root->fs_info->chunk_root, device);
        if (ret)
                goto error_undo;
@@ -1435,7 +1474,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
        spin_unlock(&root->fs_info->free_chunk_lock);
 
        device->in_fs_metadata = 0;
-       btrfs_scrub_cancel_dev(root, device);
+       btrfs_scrub_cancel_dev(root->fs_info, device);
 
        /*
         * the device list mutex makes sure that we don't change
@@ -1492,7 +1531,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
         * at this point, the device is zero sized.  We want to
         * remove it from the devices list and zero out the old super
         */
-       if (clear_super) {
+       if (clear_super && disk_super) {
                /* make sure this device isn't detected as part of
                 * the FS anymore
                 */
@@ -1522,6 +1561,53 @@ error_undo:
        goto error_brelse;
 }
 
+void btrfs_rm_dev_replace_srcdev(struct btrfs_fs_info *fs_info,
+                                struct btrfs_device *srcdev)
+{
+       WARN_ON(!mutex_is_locked(&fs_info->fs_devices->device_list_mutex));
+       list_del_rcu(&srcdev->dev_list);
+       list_del_rcu(&srcdev->dev_alloc_list);
+       fs_info->fs_devices->num_devices--;
+       if (srcdev->missing) {
+               fs_info->fs_devices->missing_devices--;
+               fs_info->fs_devices->rw_devices++;
+       }
+       if (srcdev->can_discard)
+               fs_info->fs_devices->num_can_discard--;
+       if (srcdev->bdev)
+               fs_info->fs_devices->open_devices--;
+
+       call_rcu(&srcdev->rcu, free_device);
+}
+
+void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
+                                     struct btrfs_device *tgtdev)
+{
+       struct btrfs_device *next_device;
+
+       WARN_ON(!tgtdev);
+       mutex_lock(&fs_info->fs_devices->device_list_mutex);
+       if (tgtdev->bdev) {
+               btrfs_scratch_superblock(tgtdev);
+               fs_info->fs_devices->open_devices--;
+       }
+       fs_info->fs_devices->num_devices--;
+       if (tgtdev->can_discard)
+               fs_info->fs_devices->num_can_discard++;
+
+       next_device = list_entry(fs_info->fs_devices->devices.next,
+                                struct btrfs_device, dev_list);
+       if (tgtdev->bdev == fs_info->sb->s_bdev)
+               fs_info->sb->s_bdev = next_device->bdev;
+       if (tgtdev->bdev == fs_info->fs_devices->latest_bdev)
+               fs_info->fs_devices->latest_bdev = next_device->bdev;
+       list_del_rcu(&tgtdev->dev_list);
+
+       call_rcu(&tgtdev->rcu, free_device);
+
+       mutex_unlock(&fs_info->fs_devices->device_list_mutex);
+}
+
 int btrfs_find_device_by_path(struct btrfs_root *root, char *device_path,
                              struct btrfs_device **device)
 {
@@ -1540,7 +1626,7 @@ int btrfs_find_device_by_path(struct btrfs_root *root, char *device_path,
        disk_super = (struct btrfs_super_block *)bh->b_data;
        devid = btrfs_stack_device_id(&disk_super->dev_item);
        dev_uuid = disk_super->dev_item.uuid;
-       *device = btrfs_find_device(root, devid, dev_uuid,
+       *device = btrfs_find_device(root->fs_info, devid, dev_uuid,
                                    disk_super->fsid);
        brelse(bh);
        if (!*device)
@@ -1699,7 +1785,8 @@ next_slot:
                read_extent_buffer(leaf, fs_uuid,
                                   (unsigned long)btrfs_device_fsid(dev_item),
                                   BTRFS_UUID_SIZE);
-               device = btrfs_find_device(root, devid, dev_uuid, fs_uuid);
+               device = btrfs_find_device(root->fs_info, devid, dev_uuid,
+                                          fs_uuid);
                BUG_ON(!device); /* Logic error */
 
                if (device->fs_devices->seeding) {
@@ -1807,6 +1894,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
        device->dev_root = root->fs_info->dev_root;
        device->bdev = bdev;
        device->in_fs_metadata = 1;
+       device->is_tgtdev_for_dev_replace = 0;
        device->mode = FMODE_EXCL;
        set_blocksize(device->bdev, 4096);
 
@@ -1914,6 +2002,98 @@ error:
        return ret;
 }
 
+int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
+                                 struct btrfs_device **device_out)
+{
+       struct request_queue *q;
+       struct btrfs_device *device;
+       struct block_device *bdev;
+       struct btrfs_fs_info *fs_info = root->fs_info;
+       struct list_head *devices;
+       struct rcu_string *name;
+       int ret = 0;
+
+       *device_out = NULL;
+       if (fs_info->fs_devices->seeding)
+               return -EINVAL;
+
+       bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
+                                 fs_info->bdev_holder);
+       if (IS_ERR(bdev))
+               return PTR_ERR(bdev);
+
+       filemap_write_and_wait(bdev->bd_inode->i_mapping);
+
+       devices = &fs_info->fs_devices->devices;
+       list_for_each_entry(device, devices, dev_list) {
+               if (device->bdev == bdev) {
+                       ret = -EEXIST;
+                       goto error;
+               }
+       }
+
+       device = kzalloc(sizeof(*device), GFP_NOFS);
+       if (!device) {
+               ret = -ENOMEM;
+               goto error;
+       }
+
+       name = rcu_string_strdup(device_path, GFP_NOFS);
+       if (!name) {
+               kfree(device);
+               ret = -ENOMEM;
+               goto error;
+       }
+       rcu_assign_pointer(device->name, name);
+
+       q = bdev_get_queue(bdev);
+       if (blk_queue_discard(q))
+               device->can_discard = 1;
+       mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
+       device->writeable = 1;
+       device->work.func = pending_bios_fn;
+       generate_random_uuid(device->uuid);
+       device->devid = BTRFS_DEV_REPLACE_DEVID;
+       spin_lock_init(&device->io_lock);
+       device->generation = 0;
+       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->disk_total_bytes = device->total_bytes;
+       device->dev_root = fs_info->dev_root;
+       device->bdev = bdev;
+       device->in_fs_metadata = 1;
+       device->is_tgtdev_for_dev_replace = 1;
+       device->mode = FMODE_EXCL;
+       set_blocksize(device->bdev, 4096);
+       device->fs_devices = fs_info->fs_devices;
+       list_add(&device->dev_list, &fs_info->fs_devices->devices);
+       fs_info->fs_devices->num_devices++;
+       fs_info->fs_devices->open_devices++;
+       if (device->can_discard)
+               fs_info->fs_devices->num_can_discard++;
+       mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
+
+       *device_out = device;
+       return ret;
+
+error:
+       blkdev_put(bdev, FMODE_EXCL);
+       return ret;
+}
+
+void btrfs_init_dev_replace_tgtdev_for_resume(struct btrfs_fs_info *fs_info,
+                                             struct btrfs_device *tgtdev)
+{
+       WARN_ON(fs_info->fs_devices->rw_devices == 0);
+       tgtdev->io_width = fs_info->dev_root->sectorsize;
+       tgtdev->io_align = fs_info->dev_root->sectorsize;
+       tgtdev->sector_size = fs_info->dev_root->sectorsize;
+       tgtdev->dev_root = fs_info->dev_root;
+       tgtdev->in_fs_metadata = 1;
+}
+
 static noinline int btrfs_update_device(struct btrfs_trans_handle *trans,
                                        struct btrfs_device *device)
 {
@@ -1970,7 +2150,8 @@ static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
 
        if (!device->writeable)
                return -EACCES;
-       if (new_size <= device->total_bytes)
+       if (new_size <= device->total_bytes ||
+           device->is_tgtdev_for_dev_replace)
                return -EINVAL;
 
        btrfs_set_super_total_bytes(super_copy, old_total + diff);
@@ -2599,7 +2780,8 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
                size_to_free = div_factor(old_size, 1);
                size_to_free = min(size_to_free, (u64)1 * 1024 * 1024);
                if (!device->writeable ||
-                   device->total_bytes - device->bytes_used > size_to_free)
+                   device->total_bytes - device->bytes_used > size_to_free ||
+                   device->is_tgtdev_for_dev_replace)
                        continue;
 
                ret = btrfs_shrink_device(device, old_size - size_to_free);
@@ -2777,6 +2959,7 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
        u64 allowed;
        int mixed = 0;
        int ret;
+       u64 num_devices;
 
        if (btrfs_fs_closing(fs_info) ||
            atomic_read(&fs_info->balance_pause_req) ||
@@ -2805,10 +2988,17 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
                }
        }
 
+       num_devices = fs_info->fs_devices->num_devices;
+       btrfs_dev_replace_lock(&fs_info->dev_replace);
+       if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {
+               BUG_ON(num_devices < 1);
+               num_devices--;
+       }
+       btrfs_dev_replace_unlock(&fs_info->dev_replace);
        allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE;
-       if (fs_info->fs_devices->num_devices == 1)
+       if (num_devices == 1)
                allowed |= BTRFS_BLOCK_GROUP_DUP;
-       else if (fs_info->fs_devices->num_devices < 4)
+       else if (num_devices < 4)
                allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);
        else
                allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
@@ -2951,6 +3141,7 @@ static int balance_kthread(void *data)
                ret = btrfs_balance(fs_info->balance_ctl, NULL);
        }
 
+       atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
        mutex_unlock(&fs_info->balance_mutex);
        mutex_unlock(&fs_info->volume_mutex);
 
@@ -2973,6 +3164,7 @@ int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info)
                return 0;
        }
 
+       WARN_ON(atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1));
        tsk = kthread_run(balance_kthread, fs_info, "btrfs-balance");
        if (IS_ERR(tsk))
                return PTR_ERR(tsk);
@@ -3129,6 +3321,9 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
        u64 old_size = device->total_bytes;
        u64 diff = device->total_bytes - new_size;
 
+       if (device->is_tgtdev_for_dev_replace)
+               return -EINVAL;
+
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
@@ -3398,7 +3593,8 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                        continue;
                }
 
-               if (!device->in_fs_metadata)
+               if (!device->in_fs_metadata ||
+                   device->is_tgtdev_for_dev_replace)
                        continue;
 
                if (device->total_bytes > device->bytes_used)
@@ -3427,6 +3623,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                devices_info[ndevs].total_avail = total_avail;
                devices_info[ndevs].dev = device;
                ++ndevs;
+               WARN_ON(ndevs > fs_devices->rw_devices);
        }
 
        /*
@@ -3826,13 +4023,14 @@ static int find_live_mirror(struct map_lookup *map, int first, int num,
        return optimal;
 }
 
-static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
+static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                             u64 logical, u64 *length,
                             struct btrfs_bio **bbio_ret,
                             int mirror_num)
 {
        struct extent_map *em;
        struct map_lookup *map;
+       struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
        struct extent_map_tree *em_tree = &map_tree->map_tree;
        u64 offset;
        u64 stripe_offset;
@@ -3905,7 +4103,7 @@ static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
                                            stripe_nr_end - stripe_nr_orig);
                stripe_index = do_div(stripe_nr, map->num_stripes);
        } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
-               if (rw & (REQ_WRITE | REQ_DISCARD))
+               if (rw & (REQ_WRITE | REQ_DISCARD | REQ_GET_READ_MIRRORS))
                        num_stripes = map->num_stripes;
                else if (mirror_num)
                        stripe_index = mirror_num - 1;
@@ -3917,7 +4115,7 @@ static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
                }
 
        } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
-               if (rw & (REQ_WRITE | REQ_DISCARD)) {
+               if (rw & (REQ_WRITE | REQ_DISCARD | REQ_GET_READ_MIRRORS)) {
                        num_stripes = map->num_stripes;
                } else if (mirror_num) {
                        stripe_index = mirror_num - 1;
@@ -3931,7 +4129,7 @@ static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
                stripe_index = do_div(stripe_nr, factor);
                stripe_index *= map->sub_stripes;
 
-               if (rw & REQ_WRITE)
+               if (rw & (REQ_WRITE | REQ_GET_READ_MIRRORS))
                        num_stripes = map->sub_stripes;
                else if (rw & REQ_DISCARD)
                        num_stripes = min_t(u64, map->sub_stripes *
@@ -4044,7 +4242,7 @@ static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
                }
        }
 
-       if (rw & REQ_WRITE) {
+       if (rw & (REQ_WRITE | REQ_GET_READ_MIRRORS)) {
                if (map->type & (BTRFS_BLOCK_GROUP_RAID1 |
                                 BTRFS_BLOCK_GROUP_RAID10 |
                                 BTRFS_BLOCK_GROUP_DUP)) {
@@ -4061,11 +4259,11 @@ out:
        return ret;
 }
 
-int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
+int btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                      u64 logical, u64 *length,
                      struct btrfs_bio **bbio_ret, int mirror_num)
 {
-       return __btrfs_map_block(map_tree, rw, logical, length, bbio_ret,
+       return __btrfs_map_block(fs_info, rw, logical, length, bbio_ret,
                                 mirror_num);
 }
 
@@ -4394,7 +4592,6 @@ static void bbio_error(struct btrfs_bio *bbio, struct bio *bio, u64 logical)
 int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
                  int mirror_num, int async_submit)
 {
-       struct btrfs_mapping_tree *map_tree;
        struct btrfs_device *dev;
        struct bio *first_bio = bio;
        u64 logical = (u64)bio->bi_sector << 9;
@@ -4406,12 +4603,11 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
        struct btrfs_bio *bbio = NULL;
 
        length = bio->bi_size;
-       map_tree = &root->fs_info->mapping_tree;
        map_length = length;
 
-       ret = btrfs_map_block(map_tree, rw, logical, &map_length, &bbio,
+       ret = btrfs_map_block(root->fs_info, rw, logical, &map_length, &bbio,
                              mirror_num);
-       if (ret) /* -ENOMEM */
+       if (ret)
                return ret;
 
        total_devs = bbio->num_stripes;
@@ -4464,13 +4660,13 @@ 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_fs_info *fs_info, u64 devid,
                                       u8 *uuid, u8 *fsid)
 {
        struct btrfs_device *device;
        struct btrfs_fs_devices *cur_devices;
 
-       cur_devices = root->fs_info->fs_devices;
+       cur_devices = fs_info->fs_devices;
        while (cur_devices) {
                if (!fsid ||
                    !memcmp(cur_devices->fsid, fsid, BTRFS_UUID_SIZE)) {
@@ -4568,8 +4764,8 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
                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,
-                                                       NULL);
+               map->stripes[i].dev = btrfs_find_device(root->fs_info, devid,
+                                                       uuid, NULL);
                if (!map->stripes[i].dev && !btrfs_test_opt(root, DEGRADED)) {
                        kfree(map);
                        free_extent_map(em);
@@ -4610,6 +4806,8 @@ static void fill_device_from_item(struct extent_buffer *leaf,
        device->io_align = btrfs_device_io_align(leaf, dev_item);
        device->io_width = btrfs_device_io_width(leaf, dev_item);
        device->sector_size = btrfs_device_sector_size(leaf, dev_item);
+       WARN_ON(device->devid == BTRFS_DEV_REPLACE_DEVID);
+       device->is_tgtdev_for_dev_replace = 0;
 
        ptr = (unsigned long)btrfs_device_uuid(dev_item);
        read_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
@@ -4687,7 +4885,7 @@ static int read_one_dev(struct btrfs_root *root,
                        return ret;
        }
 
-       device = btrfs_find_device(root, devid, dev_uuid, fs_uuid);
+       device = btrfs_find_device(root->fs_info, devid, dev_uuid, fs_uuid);
        if (!device || !device->bdev) {
                if (!btrfs_test_opt(root, DEGRADED))
                        return -EIO;
@@ -4720,7 +4918,7 @@ static int read_one_dev(struct btrfs_root *root,
        fill_device_from_item(leaf, dev_item, device);
        device->dev_root = root->fs_info->dev_root;
        device->in_fs_metadata = 1;
-       if (device->writeable) {
+       if (device->writeable && !device->is_tgtdev_for_dev_replace) {
                device->fs_devices->total_rw_bytes += device->total_bytes;
                spin_lock(&root->fs_info->free_chunk_lock);
                root->fs_info->free_chunk_space += device->total_bytes -
@@ -5079,7 +5277,7 @@ int btrfs_get_dev_stats(struct btrfs_root *root,
        int i;
 
        mutex_lock(&fs_devices->device_list_mutex);
-       dev = btrfs_find_device(root, stats->devid, NULL, NULL);
+       dev = btrfs_find_device(root->fs_info, stats->devid, NULL, NULL);
        mutex_unlock(&fs_devices->device_list_mutex);
 
        if (!dev) {
@@ -5107,3 +5305,21 @@ int btrfs_get_dev_stats(struct btrfs_root *root,
                stats->nr_items = BTRFS_DEV_STAT_VALUES_MAX;
        return 0;
 }
+
+int btrfs_scratch_superblock(struct btrfs_device *device)
+{
+       struct buffer_head *bh;
+       struct btrfs_super_block *disk_super;
+
+       bh = btrfs_read_dev_super(device->bdev);
+       if (!bh)
+               return -EINVAL;
+       disk_super = (struct btrfs_super_block *)bh->b_data;
+
+       memset(&disk_super->magic, 0, sizeof(disk_super->magic));
+       set_buffer_dirty(bh);
+       sync_dirty_buffer(bh);
+       brelse(bh);
+
+       return 0;
+}