Btrfs: Add new ioctl to add devices

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/ctree.h

@@ -551,6 +551,8 @@ struct btrfs_fs_info {
 	u64 data_alloc_profile;
 	u64 metadata_alloc_profile;
 	u64 system_alloc_profile;
+
+	void *bdev_holder;
 };
 
 /*

fs/btrfs/inode.c

@@ -3070,6 +3070,27 @@ static int btrfs_ioctl_defrag(struct file *file)
 	return 0;
 }
 
+long btrfs_ioctl_add_dev(struct btrfs_root *root, void __user *arg)
+{
+	struct btrfs_ioctl_vol_args *vol_args;
+	int ret;
+
+	vol_args = kmalloc(sizeof(*vol_args), GFP_NOFS);
+
+	if (!vol_args)
+		return -ENOMEM;
+
+	if (copy_from_user(vol_args, arg, sizeof(*vol_args))) {
+		ret = -EFAULT;
+		goto out;
+	}
+	ret = btrfs_init_new_device(root, vol_args->name);
+
+out:
+	kfree(vol_args);
+	return ret;
+}
+
 long btrfs_ioctl(struct file *file, unsigned int
 		cmd, unsigned long arg)
 {
@@ -3082,6 +3103,8 @@ long btrfs_ioctl(struct file *file, unsigned int
 		return btrfs_ioctl_defrag(file);
 	case BTRFS_IOC_RESIZE:
 		return btrfs_ioctl_resize(root, (void __user *)arg);
+	case BTRFS_IOC_ADD_DEV:
+		return btrfs_ioctl_add_dev(root, (void __user *)arg);
 	}
 
 	return -ENOTTY;

fs/btrfs/ioctl.h

@@ -36,4 +36,10 @@ struct btrfs_ioctl_vol_args {
 				   struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_SCAN_DEV _IOW(BTRFS_IOCTL_MAGIC, 4, \
 				   struct btrfs_ioctl_vol_args)
+#define BTRFS_IOC_ADD_DEV _IOW(BTRFS_IOCTL_MAGIC, 10, \
+				   struct btrfs_ioctl_vol_args)
+#define BTRFS_IOC_RM_DEV _IOW(BTRFS_IOCTL_MAGIC, 11, \
+				   struct btrfs_ioctl_vol_args)
+#define BTRFS_IOC_BALANCE _IOW(BTRFS_IOCTL_MAGIC, 12, \
+				   struct btrfs_ioctl_vol_args)
 #endif

fs/btrfs/super.c

@@ -388,6 +388,7 @@ int btrfs_get_sb_bdev(struct file_system_type *fs_type,
 			goto error;
 		}
 
+		btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 		s->s_flags |= MS_ACTIVE;
 	}
 

fs/btrfs/volumes.c

@@ -19,6 +19,7 @@
 #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"
@@ -592,6 +593,80 @@ int btrfs_add_device(struct btrfs_trans_handle *trans,
 	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->fs_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;
+	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;
+
+	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++;
+out:
+	btrfs_end_transaction(trans, root);
+	mutex_unlock(&root->fs_info->fs_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)
 {

fs/btrfs/volumes.h

@@ -133,4 +133,5 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 struct btrfs_device *btrfs_find_device(struct btrfs_root *root, u64 devid,
 				       u8 *uuid);
 int btrfs_shrink_device(struct btrfs_device *device, u64 new_size);
+int btrfs_init_new_device(struct btrfs_root *root, char *path);
 #endif