/*
   * bio-integrity.c - bio data integrity extensions
   *

   * Copyright (C) 2007, 2008, 2009 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/export.h>

  #include <linux/bio.h>
  #include <linux/workqueue.h>

  #include <linux/slab.h>

  #define BIP_INLINE_VECS	4

  static struct kmem_cache *bip_slab;

  static struct workqueue_struct *kintegrityd_wq;
  
  /**

   * bio_integrity_alloc - Allocate integrity payload and attach it to bio

   * @bio:	bio to attach integrity metadata to
   * @gfp_mask:	Memory allocation mask
   * @nr_vecs:	Number of integrity metadata scatter-gather elements

   *
   * Description: This function prepares a bio for attaching integrity
   * metadata.  nr_vecs specifies the maximum number of pages containing
   * integrity metadata that can be attached.
   */

  struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
  						  gfp_t gfp_mask,
  						  unsigned int nr_vecs)

  {
  	struct bio_integrity_payload *bip;

  	struct bio_set *bs = bio->bi_pool;

  	unsigned long idx = BIO_POOL_NONE;
  	unsigned inline_vecs;
  
  	if (!bs) {
  		bip = kmalloc(sizeof(struct bio_integrity_payload) +
  			      sizeof(struct bio_vec) * nr_vecs, gfp_mask);
  		inline_vecs = nr_vecs;
  	} else {

  		bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);

  		inline_vecs = BIP_INLINE_VECS;

  	}

  	if (unlikely(!bip))
  		return NULL;

  	memset(bip, 0, sizeof(*bip));

  	if (nr_vecs > inline_vecs) {
  		bip->bip_vec = bvec_alloc(gfp_mask, nr_vecs, &idx,
  					  bs->bvec_integrity_pool);
  		if (!bip->bip_vec)
  			goto err;

  		bip->bip_max_vcnt = bvec_nr_vecs(idx);

  	} else {
  		bip->bip_vec = bip->bip_inline_vecs;

  		bip->bip_max_vcnt = inline_vecs;

  	}

  	bip->bip_slab = idx;

  	bip->bip_bio = bio;
  	bio->bi_integrity = bip;

  	bio->bi_rw |= REQ_INTEGRITY;

  
  	return bip;

  err:
  	mempool_free(bip, bs->bio_integrity_pool);
  	return NULL;

  }

  EXPORT_SYMBOL(bio_integrity_alloc);
  
  /**
   * bio_integrity_free - Free bio integrity payload
   * @bio:	bio containing bip to be freed

   *
   * Description: Used to free the integrity portion of a bio. Usually
   * called from bio_free().
   */

  void bio_integrity_free(struct bio *bio)

  {

  	struct bio_integrity_payload *bip = bio_integrity(bio);

  	struct bio_set *bs = bio->bi_pool;

  	if (bip->bip_flags & BIP_BLOCK_INTEGRITY)

  		kfree(page_address(bip->bip_vec->bv_page) +
  		      bip->bip_vec->bv_offset);

  	if (bs) {
  		if (bip->bip_slab != BIO_POOL_NONE)
  			bvec_free(bs->bvec_integrity_pool, bip->bip_vec,
  				  bip->bip_slab);

  		mempool_free(bip, bs->bio_integrity_pool);

  	} else {
  		kfree(bip);
  	}

  
  	bio->bi_integrity = NULL;
  }
  EXPORT_SYMBOL(bio_integrity_free);
  
  /**
   * bio_integrity_add_page - Attach integrity metadata
   * @bio:	bio to update
   * @page:	page containing integrity metadata
   * @len:	number of bytes of integrity metadata in page
   * @offset:	start offset within page
   *
   * Description: Attach a page containing integrity metadata to bio.
   */
  int bio_integrity_add_page(struct bio *bio, struct page *page,
  			   unsigned int len, unsigned int offset)
  {

  	struct bio_integrity_payload *bip = bio_integrity(bio);

  	struct bio_vec *iv;

  	if (bip->bip_vcnt >= bip->bip_max_vcnt) {

  		printk(KERN_ERR "%s: bip_vec full
  ", __func__);
  		return 0;
  	}

  	iv = bip->bip_vec + bip->bip_vcnt;

  
  	iv->bv_page = page;
  	iv->bv_len = len;
  	iv->bv_offset = offset;
  	bip->bip_vcnt++;
  
  	return len;
  }
  EXPORT_SYMBOL(bio_integrity_add_page);
  
  /**
   * bio_integrity_enabled - Check whether integrity can be passed
   * @bio:	bio to check
   *
   * Description: Determines whether bio_integrity_prep() can be called
   * on this bio or not.	bio data direction and target device must be
   * set prior to calling.  The functions honors the write_generate and
   * read_verify flags in sysfs.
   */

  bool bio_integrity_enabled(struct bio *bio)

  {

  	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);

  	if (!bio_is_rw(bio))

  		return false;

  	/* Already protected? */
  	if (bio_integrity(bio))

  		return false;
  
  	if (bi == NULL)
  		return false;
  
  	if (bio_data_dir(bio) == READ && bi->verify_fn != NULL &&

  	    (bi->flags & BLK_INTEGRITY_VERIFY))

  		return true;
  
  	if (bio_data_dir(bio) == WRITE && bi->generate_fn != NULL &&

  	    (bi->flags & BLK_INTEGRITY_GENERATE))

  		return true;

  	return false;

  }
  EXPORT_SYMBOL(bio_integrity_enabled);
  
  /**

   * bio_integrity_intervals - Return number of integrity intervals for a bio

   * @bi:		blk_integrity profile for device

   * @sectors:	Size of the bio in 512-byte sectors

   *
   * Description: The block layer calculates everything in 512 byte

   * sectors but integrity metadata is done in terms of the data integrity
   * interval size of the storage device.  Convert the block layer sectors
   * to the appropriate number of integrity intervals.

   */

  static inline unsigned int bio_integrity_intervals(struct blk_integrity *bi,
  						   unsigned int sectors)

  {

  	return sectors >> (ilog2(bi->interval) - 9);

  }

  static inline unsigned int bio_integrity_bytes(struct blk_integrity *bi,
  					       unsigned int sectors)
  {

  	return bio_integrity_intervals(bi, sectors) * bi->tuple_size;

  }

  /**

   * bio_integrity_process - Process integrity metadata for a bio

   * @bio:	bio to generate/verify integrity metadata for

   * @proc_fn:	Pointer to the relevant processing function

   */

  static int bio_integrity_process(struct bio *bio,
  				 integrity_processing_fn *proc_fn)

  {
  	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);

  	struct blk_integrity_iter iter;

  	struct bvec_iter bviter;
  	struct bio_vec bv;

  	struct bio_integrity_payload *bip = bio_integrity(bio);

  	unsigned int ret = 0;

  	void *prot_buf = page_address(bip->bip_vec->bv_page) +
  		bip->bip_vec->bv_offset;

  	iter.disk_name = bio->bi_bdev->bd_disk->disk_name;
  	iter.interval = bi->interval;
  	iter.seed = bip_get_seed(bip);
  	iter.prot_buf = prot_buf;

  	bio_for_each_segment(bv, bio, bviter) {
  		void *kaddr = kmap_atomic(bv.bv_page);

  		iter.data_buf = kaddr + bv.bv_offset;
  		iter.data_size = bv.bv_len;

  
  		ret = proc_fn(&iter);
  		if (ret) {
  			kunmap_atomic(kaddr);
  			return ret;
  		}

  		kunmap_atomic(kaddr);

  	}

  	return ret;
  }
  
  /**

   * bio_integrity_prep - Prepare bio for integrity I/O
   * @bio:	bio to prepare
   *
   * Description: Allocates a buffer for integrity metadata, maps the
   * pages and attaches them to a bio.  The bio must have data
   * direction, target device and start sector set priot to calling.  In
   * the WRITE case, integrity metadata will be generated using the
   * block device's integrity function.  In the READ case, the buffer
   * will be prepared for DMA and a suitable end_io handler set up.
   */
  int bio_integrity_prep(struct bio *bio)
  {
  	struct bio_integrity_payload *bip;
  	struct blk_integrity *bi;
  	struct request_queue *q;
  	void *buf;
  	unsigned long start, end;
  	unsigned int len, nr_pages;
  	unsigned int bytes, offset, i;

  	unsigned int intervals;

  
  	bi = bdev_get_integrity(bio->bi_bdev);
  	q = bdev_get_queue(bio->bi_bdev);
  	BUG_ON(bi == NULL);
  	BUG_ON(bio_integrity(bio));

  	intervals = bio_integrity_intervals(bi, bio_sectors(bio));

  
  	/* Allocate kernel buffer for protection data */

  	len = intervals * bi->tuple_size;

  	buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);

  	if (unlikely(buf == NULL)) {
  		printk(KERN_ERR "could not allocate integrity buffer
  ");

  		return -ENOMEM;

  	}
  
  	end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
  	start = ((unsigned long) buf) >> PAGE_SHIFT;
  	nr_pages = end - start;
  
  	/* Allocate bio integrity payload and integrity vectors */
  	bip = bio_integrity_alloc(bio, GFP_NOIO, nr_pages);
  	if (unlikely(bip == NULL)) {
  		printk(KERN_ERR "could not allocate data integrity bioset
  ");
  		kfree(buf);
  		return -EIO;
  	}

  	bip->bip_flags |= BIP_BLOCK_INTEGRITY;

  	bip->bip_iter.bi_size = len;

  	bip_set_seed(bip, bio->bi_iter.bi_sector);

  	if (bi->flags & BLK_INTEGRITY_IP_CHECKSUM)
  		bip->bip_flags |= BIP_IP_CHECKSUM;

  	/* Map it */
  	offset = offset_in_page(buf);
  	for (i = 0 ; i < nr_pages ; i++) {
  		int ret;
  		bytes = PAGE_SIZE - offset;
  
  		if (len <= 0)
  			break;
  
  		if (bytes > len)
  			bytes = len;
  
  		ret = bio_integrity_add_page(bio, virt_to_page(buf),
  					     bytes, offset);
  
  		if (ret == 0)
  			return 0;
  
  		if (ret < bytes)
  			break;
  
  		buf += bytes;
  		len -= bytes;
  		offset = 0;
  	}
  
  	/* Install custom I/O completion handler if read verify is enabled */
  	if (bio_data_dir(bio) == READ) {
  		bip->bip_end_io = bio->bi_end_io;
  		bio->bi_end_io = bio_integrity_endio;
  	}
  
  	/* Auto-generate integrity metadata if this is a write */
  	if (bio_data_dir(bio) == WRITE)

  		bio_integrity_process(bio, bi->generate_fn);

  
  	return 0;
  }
  EXPORT_SYMBOL(bio_integrity_prep);
  
  /**

   * bio_integrity_verify_fn - Integrity I/O completion worker
   * @work:	Work struct stored in bio to be verified
   *
   * Description: This workqueue function is called to complete a READ
   * request.  The function verifies the transferred integrity metadata
   * and then calls the original bio end_io function.
   */
  static void bio_integrity_verify_fn(struct work_struct *work)
  {

  	struct bio_integrity_payload *bip =

  		container_of(work, struct bio_integrity_payload, bip_work);
  	struct bio *bio = bip->bip_bio;

  	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);

  	int error;

  	error = bio_integrity_process(bio, bi->verify_fn);

  
  	/* Restore original bio completion handler */
  	bio->bi_end_io = bip->bip_end_io;

  	bio_endio_nodec(bio, error);

  }
  
  /**
   * bio_integrity_endio - Integrity I/O completion function
   * @bio:	Protected bio
   * @error:	Pointer to errno
   *
   * Description: Completion for integrity I/O
   *
   * Normally I/O completion is done in interrupt context.  However,
   * verifying I/O integrity is a time-consuming task which must be run
   * in process context.	This function postpones completion
   * accordingly.
   */
  void bio_integrity_endio(struct bio *bio, int error)
  {

  	struct bio_integrity_payload *bip = bio_integrity(bio);

  
  	BUG_ON(bip->bip_bio != bio);

  	/* In case of an I/O error there is no point in verifying the
  	 * integrity metadata.  Restore original bio end_io handler
  	 * and run it.
  	 */
  	if (error) {
  		bio->bi_end_io = bip->bip_end_io;

  		bio_endio_nodec(bio, error);

  
  		return;
  	}

  	INIT_WORK(&bip->bip_work, bio_integrity_verify_fn);
  	queue_work(kintegrityd_wq, &bip->bip_work);
  }
  EXPORT_SYMBOL(bio_integrity_endio);
  
  /**

   * bio_integrity_advance - Advance integrity vector
   * @bio:	bio whose integrity vector to update
   * @bytes_done:	number of data bytes that have been completed
   *
   * Description: This function calculates how many integrity bytes the
   * number of completed data bytes correspond to and advances the
   * integrity vector accordingly.
   */
  void bio_integrity_advance(struct bio *bio, unsigned int bytes_done)
  {

  	struct bio_integrity_payload *bip = bio_integrity(bio);

  	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);

  	unsigned bytes = bio_integrity_bytes(bi, bytes_done >> 9);

  	bvec_iter_advance(bip->bip_vec, &bip->bip_iter, bytes);

  }
  EXPORT_SYMBOL(bio_integrity_advance);
  
  /**
   * bio_integrity_trim - Trim integrity vector
   * @bio:	bio whose integrity vector to update
   * @offset:	offset to first data sector
   * @sectors:	number of data sectors
   *
   * Description: Used to trim the integrity vector in a cloned bio.
   * The ivec will be advanced corresponding to 'offset' data sectors
   * and the length will be truncated corresponding to 'len' data
   * sectors.
   */

  void bio_integrity_trim(struct bio *bio, unsigned int offset,
  			unsigned int sectors)

  {

  	struct bio_integrity_payload *bip = bio_integrity(bio);

  	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);

  	bio_integrity_advance(bio, offset << 9);
  	bip->bip_iter.bi_size = bio_integrity_bytes(bi, sectors);

  }
  EXPORT_SYMBOL(bio_integrity_trim);
  
  /**

   * bio_integrity_clone - Callback for cloning bios with integrity metadata
   * @bio:	New bio
   * @bio_src:	Original bio

   * @gfp_mask:	Memory allocation mask

   *
   * Description:	Called to allocate a bip when cloning a bio
   */

  int bio_integrity_clone(struct bio *bio, struct bio *bio_src,

  			gfp_t gfp_mask)

  {

  	struct bio_integrity_payload *bip_src = bio_integrity(bio_src);

  	struct bio_integrity_payload *bip;
  
  	BUG_ON(bip_src == NULL);

  	bip = bio_integrity_alloc(bio, gfp_mask, bip_src->bip_vcnt);

  
  	if (bip == NULL)
  		return -EIO;
  
  	memcpy(bip->bip_vec, bip_src->bip_vec,
  	       bip_src->bip_vcnt * sizeof(struct bio_vec));

  	bip->bip_vcnt = bip_src->bip_vcnt;

  	bip->bip_iter = bip_src->bip_iter;

  
  	return 0;
  }
  EXPORT_SYMBOL(bio_integrity_clone);

  int bioset_integrity_create(struct bio_set *bs, int pool_size)

  {

  	if (bs->bio_integrity_pool)
  		return 0;

  	bs->bio_integrity_pool = mempool_create_slab_pool(pool_size, bip_slab);

  	if (!bs->bio_integrity_pool)

  		return -1;

  	bs->bvec_integrity_pool = biovec_create_pool(pool_size);

  	if (!bs->bvec_integrity_pool) {
  		mempool_destroy(bs->bio_integrity_pool);

  		return -1;

  	}

  
  	return 0;
  }
  EXPORT_SYMBOL(bioset_integrity_create);
  
  void bioset_integrity_free(struct bio_set *bs)
  {
  	if (bs->bio_integrity_pool)
  		mempool_destroy(bs->bio_integrity_pool);

  
  	if (bs->bvec_integrity_pool)

  		mempool_destroy(bs->bvec_integrity_pool);

  }
  EXPORT_SYMBOL(bioset_integrity_free);
  
  void __init bio_integrity_init(void)
  {

  	/*
  	 * kintegrityd won't block much but may burn a lot of CPU cycles.
  	 * Make it highpri CPU intensive wq with max concurrency of 1.
  	 */
  	kintegrityd_wq = alloc_workqueue("kintegrityd", WQ_MEM_RECLAIM |
  					 WQ_HIGHPRI | WQ_CPU_INTENSIVE, 1);

  	if (!kintegrityd_wq)
  		panic("Failed to create kintegrityd
  ");

  	bip_slab = kmem_cache_create("bio_integrity_payload",
  				     sizeof(struct bio_integrity_payload) +
  				     sizeof(struct bio_vec) * BIP_INLINE_VECS,
  				     0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);

  }