/*
   * blk-integrity.c - Block layer data integrity extensions
   *
   * Copyright (C) 2007, 2008 Oracle Corporation
   * Written by: Martin K. Petersen <martin.petersen@oracle.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License version
   * 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; see the file COPYING.  If not, write to
   * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
   * USA.
   *
   */
  
  #include <linux/blkdev.h>
  #include <linux/mempool.h>
  #include <linux/bio.h>
  #include <linux/scatterlist.h>

  #include <linux/slab.h>

  
  #include "blk.h"
  
  static struct kmem_cache *integrity_cachep;

  static const char *bi_unsupported_name = "unsupported";

  /**
   * blk_rq_count_integrity_sg - Count number of integrity scatterlist elements

   * @q:		request queue
   * @bio:	bio with integrity metadata attached

   *
   * Description: Returns the number of elements required in a

   * scatterlist corresponding to the integrity metadata in a bio.

   */

  int blk_rq_count_integrity_sg(struct request_queue *q, struct bio *bio)

  {

  	struct bio_vec *iv, *ivprv = NULL;
  	unsigned int segments = 0;
  	unsigned int seg_size = 0;
  	unsigned int i = 0;

  	bio_for_each_integrity_vec(iv, bio, i) {

  		if (ivprv) {
  			if (!BIOVEC_PHYS_MERGEABLE(ivprv, iv))
  				goto new_segment;
  
  			if (!BIOVEC_SEG_BOUNDARY(q, ivprv, iv))
  				goto new_segment;
  
  			if (seg_size + iv->bv_len > queue_max_segment_size(q))
  				goto new_segment;

  			seg_size += iv->bv_len;
  		} else {
  new_segment:

  			segments++;

  			seg_size = iv->bv_len;
  		}

  
  		ivprv = iv;
  	}
  
  	return segments;
  }
  EXPORT_SYMBOL(blk_rq_count_integrity_sg);
  
  /**
   * blk_rq_map_integrity_sg - Map integrity metadata into a scatterlist

   * @q:		request queue
   * @bio:	bio with integrity metadata attached

   * @sglist:	target scatterlist
   *
   * Description: Map the integrity vectors in request into a
   * scatterlist.  The scatterlist must be big enough to hold all
   * elements.  I.e. sized using blk_rq_count_integrity_sg().
   */

  int blk_rq_map_integrity_sg(struct request_queue *q, struct bio *bio,
  			    struct scatterlist *sglist)

  {

  	struct bio_vec *iv, *ivprv = NULL;
  	struct scatterlist *sg = NULL;
  	unsigned int segments = 0;
  	unsigned int i = 0;

  	bio_for_each_integrity_vec(iv, bio, i) {

  
  		if (ivprv) {
  			if (!BIOVEC_PHYS_MERGEABLE(ivprv, iv))
  				goto new_segment;

  			if (!BIOVEC_SEG_BOUNDARY(q, ivprv, iv))
  				goto new_segment;
  
  			if (sg->length + iv->bv_len > queue_max_segment_size(q))
  				goto new_segment;

  			sg->length += iv->bv_len;
  		} else {
  new_segment:
  			if (!sg)
  				sg = sglist;
  			else {
  				sg->page_link &= ~0x02;
  				sg = sg_next(sg);
  			}
  
  			sg_set_page(sg, iv->bv_page, iv->bv_len, iv->bv_offset);
  			segments++;
  		}
  
  		ivprv = iv;
  	}
  
  	if (sg)
  		sg_mark_end(sg);
  
  	return segments;
  }
  EXPORT_SYMBOL(blk_rq_map_integrity_sg);
  
  /**

   * blk_integrity_compare - Compare integrity profile of two disks
   * @gd1:	Disk to compare
   * @gd2:	Disk to compare

   *
   * Description: Meta-devices like DM and MD need to verify that all
   * sub-devices use the same integrity format before advertising to
   * upper layers that they can send/receive integrity metadata.  This

   * function can be used to check whether two gendisk devices have

   * compatible integrity formats.
   */

  int blk_integrity_compare(struct gendisk *gd1, struct gendisk *gd2)

  {

  	struct blk_integrity *b1 = gd1->integrity;
  	struct blk_integrity *b2 = gd2->integrity;

  	if (!b1 && !b2)
  		return 0;

  
  	if (!b1 || !b2)

  		return -1;

  
  	if (b1->sector_size != b2->sector_size) {
  		printk(KERN_ERR "%s: %s/%s sector sz %u != %u
  ", __func__,

  		       gd1->disk_name, gd2->disk_name,

  		       b1->sector_size, b2->sector_size);
  		return -1;
  	}
  
  	if (b1->tuple_size != b2->tuple_size) {
  		printk(KERN_ERR "%s: %s/%s tuple sz %u != %u
  ", __func__,

  		       gd1->disk_name, gd2->disk_name,

  		       b1->tuple_size, b2->tuple_size);
  		return -1;
  	}
  
  	if (b1->tag_size && b2->tag_size && (b1->tag_size != b2->tag_size)) {
  		printk(KERN_ERR "%s: %s/%s tag sz %u != %u
  ", __func__,

  		       gd1->disk_name, gd2->disk_name,

  		       b1->tag_size, b2->tag_size);
  		return -1;
  	}
  
  	if (strcmp(b1->name, b2->name)) {
  		printk(KERN_ERR "%s: %s/%s type %s != %s
  ", __func__,

  		       gd1->disk_name, gd2->disk_name,

  		       b1->name, b2->name);
  		return -1;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL(blk_integrity_compare);

  int blk_integrity_merge_rq(struct request_queue *q, struct request *req,
  			   struct request *next)
  {
  	if (blk_integrity_rq(req) != blk_integrity_rq(next))
  		return -1;
  
  	if (req->nr_integrity_segments + next->nr_integrity_segments >
  	    q->limits.max_integrity_segments)
  		return -1;
  
  	return 0;
  }
  EXPORT_SYMBOL(blk_integrity_merge_rq);
  
  int blk_integrity_merge_bio(struct request_queue *q, struct request *req,
  			    struct bio *bio)
  {
  	int nr_integrity_segs;
  	struct bio *next = bio->bi_next;
  
  	bio->bi_next = NULL;
  	nr_integrity_segs = blk_rq_count_integrity_sg(q, bio);
  	bio->bi_next = next;
  
  	if (req->nr_integrity_segments + nr_integrity_segs >
  	    q->limits.max_integrity_segments)
  		return -1;
  
  	req->nr_integrity_segments += nr_integrity_segs;
  
  	return 0;
  }
  EXPORT_SYMBOL(blk_integrity_merge_bio);

  struct integrity_sysfs_entry {
  	struct attribute attr;
  	ssize_t (*show)(struct blk_integrity *, char *);
  	ssize_t (*store)(struct blk_integrity *, const char *, size_t);
  };
  
  static ssize_t integrity_attr_show(struct kobject *kobj, struct attribute *attr,
  				   char *page)
  {
  	struct blk_integrity *bi =
  		container_of(kobj, struct blk_integrity, kobj);
  	struct integrity_sysfs_entry *entry =
  		container_of(attr, struct integrity_sysfs_entry, attr);
  
  	return entry->show(bi, page);
  }

  static ssize_t integrity_attr_store(struct kobject *kobj,
  				    struct attribute *attr, const char *page,
  				    size_t count)

  {
  	struct blk_integrity *bi =
  		container_of(kobj, struct blk_integrity, kobj);
  	struct integrity_sysfs_entry *entry =
  		container_of(attr, struct integrity_sysfs_entry, attr);
  	ssize_t ret = 0;
  
  	if (entry->store)
  		ret = entry->store(bi, page, count);
  
  	return ret;
  }
  
  static ssize_t integrity_format_show(struct blk_integrity *bi, char *page)
  {
  	if (bi != NULL && bi->name != NULL)
  		return sprintf(page, "%s
  ", bi->name);
  	else
  		return sprintf(page, "none
  ");
  }
  
  static ssize_t integrity_tag_size_show(struct blk_integrity *bi, char *page)
  {
  	if (bi != NULL)
  		return sprintf(page, "%u
  ", bi->tag_size);
  	else
  		return sprintf(page, "0
  ");
  }
  
  static ssize_t integrity_read_store(struct blk_integrity *bi,
  				    const char *page, size_t count)
  {
  	char *p = (char *) page;
  	unsigned long val = simple_strtoul(p, &p, 10);
  
  	if (val)

  		bi->flags |= INTEGRITY_FLAG_READ;

  	else

  		bi->flags &= ~INTEGRITY_FLAG_READ;

  
  	return count;
  }
  
  static ssize_t integrity_read_show(struct blk_integrity *bi, char *page)
  {

  	return sprintf(page, "%d
  ", (bi->flags & INTEGRITY_FLAG_READ) != 0);

  }
  
  static ssize_t integrity_write_store(struct blk_integrity *bi,
  				     const char *page, size_t count)
  {
  	char *p = (char *) page;
  	unsigned long val = simple_strtoul(p, &p, 10);
  
  	if (val)

  		bi->flags |= INTEGRITY_FLAG_WRITE;

  	else

  		bi->flags &= ~INTEGRITY_FLAG_WRITE;

  
  	return count;
  }
  
  static ssize_t integrity_write_show(struct blk_integrity *bi, char *page)
  {

  	return sprintf(page, "%d
  ", (bi->flags & INTEGRITY_FLAG_WRITE) != 0);

  }
  
  static struct integrity_sysfs_entry integrity_format_entry = {
  	.attr = { .name = "format", .mode = S_IRUGO },
  	.show = integrity_format_show,
  };
  
  static struct integrity_sysfs_entry integrity_tag_size_entry = {
  	.attr = { .name = "tag_size", .mode = S_IRUGO },
  	.show = integrity_tag_size_show,
  };
  
  static struct integrity_sysfs_entry integrity_read_entry = {
  	.attr = { .name = "read_verify", .mode = S_IRUGO | S_IWUSR },
  	.show = integrity_read_show,
  	.store = integrity_read_store,
  };
  
  static struct integrity_sysfs_entry integrity_write_entry = {
  	.attr = { .name = "write_generate", .mode = S_IRUGO | S_IWUSR },
  	.show = integrity_write_show,
  	.store = integrity_write_store,
  };
  
  static struct attribute *integrity_attrs[] = {
  	&integrity_format_entry.attr,
  	&integrity_tag_size_entry.attr,
  	&integrity_read_entry.attr,
  	&integrity_write_entry.attr,
  	NULL,
  };

  static const struct sysfs_ops integrity_ops = {

  	.show	= &integrity_attr_show,
  	.store	= &integrity_attr_store,
  };
  
  static int __init blk_dev_integrity_init(void)
  {
  	integrity_cachep = kmem_cache_create("blkdev_integrity",
  					     sizeof(struct blk_integrity),
  					     0, SLAB_PANIC, NULL);
  	return 0;
  }
  subsys_initcall(blk_dev_integrity_init);
  
  static void blk_integrity_release(struct kobject *kobj)
  {
  	struct blk_integrity *bi =
  		container_of(kobj, struct blk_integrity, kobj);
  
  	kmem_cache_free(integrity_cachep, bi);
  }
  
  static struct kobj_type integrity_ktype = {
  	.default_attrs	= integrity_attrs,
  	.sysfs_ops	= &integrity_ops,
  	.release	= blk_integrity_release,
  };

  bool blk_integrity_is_initialized(struct gendisk *disk)
  {
  	struct blk_integrity *bi = blk_get_integrity(disk);
  
  	return (bi && bi->name && strcmp(bi->name, bi_unsupported_name) != 0);
  }
  EXPORT_SYMBOL(blk_integrity_is_initialized);

  /**
   * blk_integrity_register - Register a gendisk as being integrity-capable
   * @disk:	struct gendisk pointer to make integrity-aware

   * @template:	optional integrity profile to register

   *
   * Description: When a device needs to advertise itself as being able
   * to send/receive integrity metadata it must use this function to
   * register the capability with the block layer.  The template is a
   * blk_integrity struct with values appropriate for the underlying

   * hardware.  If template is NULL the new profile is allocated but
   * not filled out. See Documentation/block/data-integrity.txt.

   */
  int blk_integrity_register(struct gendisk *disk, struct blk_integrity *template)
  {
  	struct blk_integrity *bi;
  
  	BUG_ON(disk == NULL);

  
  	if (disk->integrity == NULL) {

  		bi = kmem_cache_alloc(integrity_cachep,

  				      GFP_KERNEL | __GFP_ZERO);

  		if (!bi)
  			return -1;
  
  		if (kobject_init_and_add(&bi->kobj, &integrity_ktype,

  					 &disk_to_dev(disk)->kobj,
  					 "%s", "integrity")) {

  			kmem_cache_free(integrity_cachep, bi);
  			return -1;
  		}
  
  		kobject_uevent(&bi->kobj, KOBJ_ADD);

  		bi->flags |= INTEGRITY_FLAG_READ | INTEGRITY_FLAG_WRITE;

  		bi->sector_size = queue_logical_block_size(disk->queue);

  		disk->integrity = bi;
  	} else
  		bi = disk->integrity;
  
  	/* Use the provided profile as template */

  	if (template != NULL) {
  		bi->name = template->name;
  		bi->generate_fn = template->generate_fn;
  		bi->verify_fn = template->verify_fn;
  		bi->tuple_size = template->tuple_size;
  		bi->set_tag_fn = template->set_tag_fn;
  		bi->get_tag_fn = template->get_tag_fn;
  		bi->tag_size = template->tag_size;
  	} else

  		bi->name = bi_unsupported_name;

  
  	return 0;
  }
  EXPORT_SYMBOL(blk_integrity_register);
  
  /**
   * blk_integrity_unregister - Remove block integrity profile
   * @disk:	disk whose integrity profile to deallocate
   *
   * Description: This function frees all memory used by the block
   * integrity profile.  To be called at device teardown.
   */
  void blk_integrity_unregister(struct gendisk *disk)
  {
  	struct blk_integrity *bi;
  
  	if (!disk || !disk->integrity)
  		return;
  
  	bi = disk->integrity;
  
  	kobject_uevent(&bi->kobj, KOBJ_REMOVE);
  	kobject_del(&bi->kobj);

  	kobject_put(&bi->kobj);

  	disk->integrity = NULL;

  }
  EXPORT_SYMBOL(blk_integrity_unregister);