/*
   * Copyright (c) 2014 Christoph Hellwig.
   */
  #include <linux/sunrpc/svc.h>
  #include <linux/blkdev.h>
  #include <linux/nfs4.h>
  #include <linux/nfs_fs.h>
  #include <linux/nfs_xdr.h>
  
  #include "blocklayout.h"
  
  #define NFSDBG_FACILITY		NFSDBG_PNFS_LD
  
  static void
  bl_free_device(struct pnfs_block_dev *dev)
  {
  	if (dev->nr_children) {
  		int i;
  
  		for (i = 0; i < dev->nr_children; i++)
  			bl_free_device(&dev->children[i]);
  		kfree(dev->children);
  	} else {
  		if (dev->bdev)
  			blkdev_put(dev->bdev, FMODE_READ | FMODE_WRITE);
  	}
  }
  
  void
  bl_free_deviceid_node(struct nfs4_deviceid_node *d)
  {
  	struct pnfs_block_dev *dev =
  		container_of(d, struct pnfs_block_dev, node);
  
  	bl_free_device(dev);
  	kfree_rcu(dev, node.rcu);
  }
  
  static int
  nfs4_block_decode_volume(struct xdr_stream *xdr, struct pnfs_block_volume *b)
  {
  	__be32 *p;
  	int i;
  
  	p = xdr_inline_decode(xdr, 4);
  	if (!p)
  		return -EIO;
  	b->type = be32_to_cpup(p++);
  
  	switch (b->type) {
  	case PNFS_BLOCK_VOLUME_SIMPLE:
  		p = xdr_inline_decode(xdr, 4);
  		if (!p)
  			return -EIO;
  		b->simple.nr_sigs = be32_to_cpup(p++);
  		if (!b->simple.nr_sigs) {
  			dprintk("no signature
  ");
  			return -EIO;
  		}
  
  		b->simple.len = 4 + 4;
  		for (i = 0; i < b->simple.nr_sigs; i++) {
  			p = xdr_inline_decode(xdr, 8 + 4);
  			if (!p)
  				return -EIO;
  			p = xdr_decode_hyper(p, &b->simple.sigs[i].offset);
  			b->simple.sigs[i].sig_len = be32_to_cpup(p++);
  			if (b->simple.sigs[i].sig_len > PNFS_BLOCK_UUID_LEN) {
  				pr_info("signature too long: %d
  ",
  					b->simple.sigs[i].sig_len);
  				return -EIO;
  			}
  
  			p = xdr_inline_decode(xdr, b->simple.sigs[i].sig_len);
  			if (!p)
  				return -EIO;
  			memcpy(&b->simple.sigs[i].sig, p,
  				b->simple.sigs[i].sig_len);
  
  			b->simple.len += 8 + 4 + b->simple.sigs[i].sig_len;
  		}
  		break;
  	case PNFS_BLOCK_VOLUME_SLICE:
  		p = xdr_inline_decode(xdr, 8 + 8 + 4);
  		if (!p)
  			return -EIO;
  		p = xdr_decode_hyper(p, &b->slice.start);
  		p = xdr_decode_hyper(p, &b->slice.len);
  		b->slice.volume = be32_to_cpup(p++);
  		break;
  	case PNFS_BLOCK_VOLUME_CONCAT:
  		p = xdr_inline_decode(xdr, 4);
  		if (!p)
  			return -EIO;
  		b->concat.volumes_count = be32_to_cpup(p++);
  
  		p = xdr_inline_decode(xdr, b->concat.volumes_count * 4);
  		if (!p)
  			return -EIO;
  		for (i = 0; i < b->concat.volumes_count; i++)
  			b->concat.volumes[i] = be32_to_cpup(p++);
  		break;
  	case PNFS_BLOCK_VOLUME_STRIPE:
  		p = xdr_inline_decode(xdr, 8 + 4);
  		if (!p)
  			return -EIO;
  		p = xdr_decode_hyper(p, &b->stripe.chunk_size);
  		b->stripe.volumes_count = be32_to_cpup(p++);
  
  		p = xdr_inline_decode(xdr, b->stripe.volumes_count * 4);
  		if (!p)
  			return -EIO;
  		for (i = 0; i < b->stripe.volumes_count; i++)
  			b->stripe.volumes[i] = be32_to_cpup(p++);
  		break;
  	default:
  		dprintk("unknown volume type!
  ");
  		return -EIO;
  	}
  
  	return 0;
  }
  
  static bool bl_map_simple(struct pnfs_block_dev *dev, u64 offset,
  		struct pnfs_block_dev_map *map)
  {
  	map->start = dev->start;
  	map->len = dev->len;
  	map->disk_offset = dev->disk_offset;
  	map->bdev = dev->bdev;
  	return true;
  }
  
  static bool bl_map_concat(struct pnfs_block_dev *dev, u64 offset,
  		struct pnfs_block_dev_map *map)
  {
  	int i;
  
  	for (i = 0; i < dev->nr_children; i++) {
  		struct pnfs_block_dev *child = &dev->children[i];
  
  		if (child->start > offset ||
  		    child->start + child->len <= offset)
  			continue;
  
  		child->map(child, offset - child->start, map);
  		return true;
  	}
  
  	dprintk("%s: ran off loop!
  ", __func__);
  	return false;
  }
  
  static bool bl_map_stripe(struct pnfs_block_dev *dev, u64 offset,
  		struct pnfs_block_dev_map *map)
  {
  	struct pnfs_block_dev *child;
  	u64 chunk;
  	u32 chunk_idx;
  	u64 disk_offset;
  
  	chunk = div_u64(offset, dev->chunk_size);
  	div_u64_rem(chunk, dev->nr_children, &chunk_idx);
  
  	if (chunk_idx > dev->nr_children) {
  		dprintk("%s: invalid chunk idx %d (%lld/%lld)
  ",
  			__func__, chunk_idx, offset, dev->chunk_size);
  		/* error, should not happen */
  		return false;
  	}
  
  	/* truncate offset to the beginning of the stripe */
  	offset = chunk * dev->chunk_size;
  
  	/* disk offset of the stripe */
  	disk_offset = div_u64(offset, dev->nr_children);
  
  	child = &dev->children[chunk_idx];
  	child->map(child, disk_offset, map);
  
  	map->start += offset;
  	map->disk_offset += disk_offset;
  	map->len = dev->chunk_size;
  	return true;
  }
  
  static int
  bl_parse_deviceid(struct nfs_server *server, struct pnfs_block_dev *d,
  		struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask);
  
  
  static int
  bl_parse_simple(struct nfs_server *server, struct pnfs_block_dev *d,
  		struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask)
  {
  	struct pnfs_block_volume *v = &volumes[idx];
  	dev_t dev;
  
  	dev = bl_resolve_deviceid(server, v, gfp_mask);
  	if (!dev)
  		return -EIO;
  
  	d->bdev = blkdev_get_by_dev(dev, FMODE_READ | FMODE_WRITE, NULL);
  	if (IS_ERR(d->bdev)) {
  		printk(KERN_WARNING "pNFS: failed to open device %d:%d (%ld)
  ",
  			MAJOR(dev), MINOR(dev), PTR_ERR(d->bdev));
  		return PTR_ERR(d->bdev);
  	}
  
  
  	d->len = i_size_read(d->bdev->bd_inode);
  	d->map = bl_map_simple;
  
  	printk(KERN_INFO "pNFS: using block device %s
  ",
  		d->bdev->bd_disk->disk_name);
  	return 0;
  }
  
  static int
  bl_parse_slice(struct nfs_server *server, struct pnfs_block_dev *d,
  		struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask)
  {
  	struct pnfs_block_volume *v = &volumes[idx];
  	int ret;
  
  	ret = bl_parse_deviceid(server, d, volumes, v->slice.volume, gfp_mask);
  	if (ret)
  		return ret;
  
  	d->disk_offset = v->slice.start;
  	d->len = v->slice.len;
  	return 0;
  }
  
  static int
  bl_parse_concat(struct nfs_server *server, struct pnfs_block_dev *d,
  		struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask)
  {
  	struct pnfs_block_volume *v = &volumes[idx];
  	u64 len = 0;
  	int ret, i;
  
  	d->children = kcalloc(v->concat.volumes_count,
  			sizeof(struct pnfs_block_dev), GFP_KERNEL);
  	if (!d->children)
  		return -ENOMEM;
  
  	for (i = 0; i < v->concat.volumes_count; i++) {
  		ret = bl_parse_deviceid(server, &d->children[i],
  				volumes, v->concat.volumes[i], gfp_mask);
  		if (ret)
  			return ret;
  
  		d->nr_children++;
  		d->children[i].start += len;
  		len += d->children[i].len;
  	}
  
  	d->len = len;
  	d->map = bl_map_concat;
  	return 0;
  }
  
  static int
  bl_parse_stripe(struct nfs_server *server, struct pnfs_block_dev *d,
  		struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask)
  {
  	struct pnfs_block_volume *v = &volumes[idx];
  	u64 len = 0;
  	int ret, i;
  
  	d->children = kcalloc(v->stripe.volumes_count,
  			sizeof(struct pnfs_block_dev), GFP_KERNEL);
  	if (!d->children)
  		return -ENOMEM;
  
  	for (i = 0; i < v->stripe.volumes_count; i++) {
  		ret = bl_parse_deviceid(server, &d->children[i],
  				volumes, v->stripe.volumes[i], gfp_mask);
  		if (ret)
  			return ret;
  
  		d->nr_children++;
  		len += d->children[i].len;
  	}
  
  	d->len = len;
  	d->chunk_size = v->stripe.chunk_size;
  	d->map = bl_map_stripe;
  	return 0;
  }
  
  static int
  bl_parse_deviceid(struct nfs_server *server, struct pnfs_block_dev *d,
  		struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask)
  {
  	switch (volumes[idx].type) {
  	case PNFS_BLOCK_VOLUME_SIMPLE:
  		return bl_parse_simple(server, d, volumes, idx, gfp_mask);
  	case PNFS_BLOCK_VOLUME_SLICE:
  		return bl_parse_slice(server, d, volumes, idx, gfp_mask);
  	case PNFS_BLOCK_VOLUME_CONCAT:
  		return bl_parse_concat(server, d, volumes, idx, gfp_mask);
  	case PNFS_BLOCK_VOLUME_STRIPE:
  		return bl_parse_stripe(server, d, volumes, idx, gfp_mask);
  	default:
  		dprintk("unsupported volume type: %d
  ", volumes[idx].type);
  		return -EIO;
  	}
  }
  
  struct nfs4_deviceid_node *
  bl_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
  		gfp_t gfp_mask)
  {
  	struct nfs4_deviceid_node *node = NULL;
  	struct pnfs_block_volume *volumes;
  	struct pnfs_block_dev *top;
  	struct xdr_stream xdr;
  	struct xdr_buf buf;
  	struct page *scratch;
  	int nr_volumes, ret, i;
  	__be32 *p;
  
  	scratch = alloc_page(gfp_mask);
  	if (!scratch)
  		goto out;
  
  	xdr_init_decode_pages(&xdr, &buf, pdev->pages, pdev->pglen);
  	xdr_set_scratch_buffer(&xdr, page_address(scratch), PAGE_SIZE);
  
  	p = xdr_inline_decode(&xdr, sizeof(__be32));
  	if (!p)
  		goto out_free_scratch;
  	nr_volumes = be32_to_cpup(p++);
  
  	volumes = kcalloc(nr_volumes, sizeof(struct pnfs_block_volume),
  			  gfp_mask);
  	if (!volumes)
  		goto out_free_scratch;
  
  	for (i = 0; i < nr_volumes; i++) {
  		ret = nfs4_block_decode_volume(&xdr, &volumes[i]);
  		if (ret < 0)
  			goto out_free_volumes;
  	}
  
  	top = kzalloc(sizeof(*top), gfp_mask);
  	if (!top)
  		goto out_free_volumes;
  
  	ret = bl_parse_deviceid(server, top, volumes, nr_volumes - 1, gfp_mask);
  	if (ret) {
  		bl_free_device(top);
  		kfree(top);
  		goto out_free_volumes;
  	}
  
  	node = &top->node;
  	nfs4_init_deviceid_node(node, server, &pdev->dev_id);
  
  out_free_volumes:
  	kfree(volumes);
  out_free_scratch:
  	__free_page(scratch);
  out:
  	return node;
  }