/*
   *  linux/fs/nfs/blocklayout/blocklayout.c
   *
   *  Module for the NFSv4.1 pNFS block layout driver.
   *
   *  Copyright (c) 2006 The Regents of the University of Michigan.
   *  All rights reserved.
   *
   *  Andy Adamson <andros@citi.umich.edu>
   *  Fred Isaman <iisaman@umich.edu>
   *
   * permission is granted to use, copy, create derivative works and
   * redistribute this software and such derivative works for any purpose,
   * so long as the name of the university of michigan is not used in
   * any advertising or publicity pertaining to the use or distribution
   * of this software without specific, written prior authorization.  if
   * the above copyright notice or any other identification of the
   * university of michigan is included in any copy of any portion of
   * this software, then the disclaimer below must also be included.
   *
   * this software is provided as is, without representation from the
   * university of michigan as to its fitness for any purpose, and without
   * warranty by the university of michigan of any kind, either express
   * or implied, including without limitation the implied warranties of
   * merchantability and fitness for a particular purpose.  the regents
   * of the university of michigan shall not be liable for any damages,
   * including special, indirect, incidental, or consequential damages,
   * with respect to any claim arising out or in connection with the use
   * of the software, even if it has been or is hereafter advised of the
   * possibility of such damages.
   */

  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/mount.h>
  #include <linux/namei.h>

  #include <linux/bio.h>		/* struct bio */

  #include <linux/buffer_head.h>	/* various write calls */

  #include <linux/prefetch.h>

  
  #include "blocklayout.h"
  
  #define NFSDBG_FACILITY	NFSDBG_PNFS_LD
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Andy Adamson <andros@citi.umich.edu>");
  MODULE_DESCRIPTION("The NFSv4.1 pNFS Block layout driver");

  struct dentry *bl_device_pipe;
  wait_queue_head_t bl_wq;

  static void print_page(struct page *page)
  {
  	dprintk("PRINTPAGE page %p
  ", page);
  	dprintk("	PagePrivate %d
  ", PagePrivate(page));
  	dprintk("	PageUptodate %d
  ", PageUptodate(page));
  	dprintk("	PageError %d
  ", PageError(page));
  	dprintk("	PageDirty %d
  ", PageDirty(page));
  	dprintk("	PageReferenced %d
  ", PageReferenced(page));
  	dprintk("	PageLocked %d
  ", PageLocked(page));
  	dprintk("	PageWriteback %d
  ", PageWriteback(page));
  	dprintk("	PageMappedToDisk %d
  ", PageMappedToDisk(page));
  	dprintk("
  ");
  }
  
  /* Given the be associated with isect, determine if page data needs to be
   * initialized.
   */
  static int is_hole(struct pnfs_block_extent *be, sector_t isect)
  {
  	if (be->be_state == PNFS_BLOCK_NONE_DATA)
  		return 1;
  	else if (be->be_state != PNFS_BLOCK_INVALID_DATA)
  		return 0;
  	else
  		return !bl_is_sector_init(be->be_inval, isect);
  }

  /* Given the be associated with isect, determine if page data can be
   * written to disk.
   */
  static int is_writable(struct pnfs_block_extent *be, sector_t isect)
  {

  	return (be->be_state == PNFS_BLOCK_READWRITE_DATA ||
  		be->be_state == PNFS_BLOCK_INVALID_DATA);

  }

  /* The data we are handed might be spread across several bios.  We need
   * to track when the last one is finished.
   */
  struct parallel_io {
  	struct kref refcnt;

  	void (*pnfs_callback) (void *data, int num_se);

  	void *data;

  	int bse_count;

  };
  
  static inline struct parallel_io *alloc_parallel(void *data)
  {
  	struct parallel_io *rv;
  
  	rv  = kmalloc(sizeof(*rv), GFP_NOFS);
  	if (rv) {
  		rv->data = data;
  		kref_init(&rv->refcnt);

  		rv->bse_count = 0;

  	}
  	return rv;
  }
  
  static inline void get_parallel(struct parallel_io *p)
  {
  	kref_get(&p->refcnt);
  }
  
  static void destroy_parallel(struct kref *kref)
  {
  	struct parallel_io *p = container_of(kref, struct parallel_io, refcnt);
  
  	dprintk("%s enter
  ", __func__);

  	p->pnfs_callback(p->data, p->bse_count);

  	kfree(p);
  }
  
  static inline void put_parallel(struct parallel_io *p)
  {
  	kref_put(&p->refcnt, destroy_parallel);
  }
  
  static struct bio *
  bl_submit_bio(int rw, struct bio *bio)
  {
  	if (bio) {
  		get_parallel(bio->bi_private);
  		dprintk("%s submitting %s bio %u@%llu
  ", __func__,
  			rw == READ ? "read" : "write",
  			bio->bi_size, (unsigned long long)bio->bi_sector);
  		submit_bio(rw, bio);
  	}
  	return NULL;
  }
  
  static struct bio *bl_alloc_init_bio(int npg, sector_t isect,
  				     struct pnfs_block_extent *be,
  				     void (*end_io)(struct bio *, int err),
  				     struct parallel_io *par)
  {
  	struct bio *bio;

  	npg = min(npg, BIO_MAX_PAGES);

  	bio = bio_alloc(GFP_NOIO, npg);

  	if (!bio && (current->flags & PF_MEMALLOC)) {
  		while (!bio && (npg /= 2))
  			bio = bio_alloc(GFP_NOIO, npg);
  	}

  	if (bio) {
  		bio->bi_sector = isect - be->be_f_offset + be->be_v_offset;
  		bio->bi_bdev = be->be_mdev;
  		bio->bi_end_io = end_io;
  		bio->bi_private = par;
  	}

  	return bio;
  }
  
  static struct bio *bl_add_page_to_bio(struct bio *bio, int npg, int rw,
  				      sector_t isect, struct page *page,
  				      struct pnfs_block_extent *be,
  				      void (*end_io)(struct bio *, int err),
  				      struct parallel_io *par)
  {
  retry:
  	if (!bio) {
  		bio = bl_alloc_init_bio(npg, isect, be, end_io, par);
  		if (!bio)
  			return ERR_PTR(-ENOMEM);
  	}
  	if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
  		bio = bl_submit_bio(rw, bio);
  		goto retry;
  	}
  	return bio;
  }

  /* This is basically copied from mpage_end_io_read */
  static void bl_end_io_read(struct bio *bio, int err)
  {
  	struct parallel_io *par = bio->bi_private;
  	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
  	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
  	struct nfs_read_data *rdata = (struct nfs_read_data *)par->data;
  
  	do {
  		struct page *page = bvec->bv_page;
  
  		if (--bvec >= bio->bi_io_vec)
  			prefetchw(&bvec->bv_page->flags);
  		if (uptodate)
  			SetPageUptodate(page);
  	} while (bvec >= bio->bi_io_vec);
  	if (!uptodate) {
  		if (!rdata->pnfs_error)
  			rdata->pnfs_error = -EIO;

  		pnfs_set_lo_fail(rdata->lseg);

  	}
  	bio_put(bio);
  	put_parallel(par);
  }
  
  static void bl_read_cleanup(struct work_struct *work)
  {
  	struct rpc_task *task;
  	struct nfs_read_data *rdata;
  	dprintk("%s enter
  ", __func__);
  	task = container_of(work, struct rpc_task, u.tk_work);
  	rdata = container_of(task, struct nfs_read_data, task);
  	pnfs_ld_read_done(rdata);
  }
  
  static void

  bl_end_par_io_read(void *data, int unused)

  {
  	struct nfs_read_data *rdata = data;

  	rdata->task.tk_status = rdata->pnfs_error;

  	INIT_WORK(&rdata->task.u.tk_work, bl_read_cleanup);
  	schedule_work(&rdata->task.u.tk_work);
  }

  static enum pnfs_try_status
  bl_read_pagelist(struct nfs_read_data *rdata)
  {

  	int i, hole;
  	struct bio *bio = NULL;
  	struct pnfs_block_extent *be = NULL, *cow_read = NULL;
  	sector_t isect, extent_length = 0;
  	struct parallel_io *par;
  	loff_t f_offset = rdata->args.offset;
  	size_t count = rdata->args.count;
  	struct page **pages = rdata->args.pages;
  	int pg_index = rdata->args.pgbase >> PAGE_CACHE_SHIFT;
  
  	dprintk("%s enter nr_pages %u offset %lld count %Zd
  ", __func__,
  	       rdata->npages, f_offset, count);
  
  	par = alloc_parallel(rdata);
  	if (!par)
  		goto use_mds;

  	par->pnfs_callback = bl_end_par_io_read;
  	/* At this point, we can no longer jump to use_mds */
  
  	isect = (sector_t) (f_offset >> SECTOR_SHIFT);
  	/* Code assumes extents are page-aligned */
  	for (i = pg_index; i < rdata->npages; i++) {
  		if (!extent_length) {
  			/* We've used up the previous extent */
  			bl_put_extent(be);
  			bl_put_extent(cow_read);
  			bio = bl_submit_bio(READ, bio);
  			/* Get the next one */
  			be = bl_find_get_extent(BLK_LSEG2EXT(rdata->lseg),
  					     isect, &cow_read);
  			if (!be) {
  				rdata->pnfs_error = -EIO;
  				goto out;
  			}
  			extent_length = be->be_length -
  				(isect - be->be_f_offset);
  			if (cow_read) {
  				sector_t cow_length = cow_read->be_length -
  					(isect - cow_read->be_f_offset);
  				extent_length = min(extent_length, cow_length);
  			}
  		}
  		hole = is_hole(be, isect);
  		if (hole && !cow_read) {
  			bio = bl_submit_bio(READ, bio);
  			/* Fill hole w/ zeroes w/o accessing device */
  			dprintk("%s Zeroing page for hole
  ", __func__);
  			zero_user_segment(pages[i], 0, PAGE_CACHE_SIZE);
  			print_page(pages[i]);
  			SetPageUptodate(pages[i]);
  		} else {
  			struct pnfs_block_extent *be_read;
  
  			be_read = (hole && cow_read) ? cow_read : be;
  			bio = bl_add_page_to_bio(bio, rdata->npages - i, READ,
  						 isect, pages[i], be_read,
  						 bl_end_io_read, par);
  			if (IS_ERR(bio)) {
  				rdata->pnfs_error = PTR_ERR(bio);

  				bio = NULL;

  				goto out;
  			}
  		}
  		isect += PAGE_CACHE_SECTORS;
  		extent_length -= PAGE_CACHE_SECTORS;
  	}
  	if ((isect << SECTOR_SHIFT) >= rdata->inode->i_size) {
  		rdata->res.eof = 1;
  		rdata->res.count = rdata->inode->i_size - f_offset;
  	} else {
  		rdata->res.count = (isect << SECTOR_SHIFT) - f_offset;
  	}
  out:
  	bl_put_extent(be);
  	bl_put_extent(cow_read);
  	bl_submit_bio(READ, bio);
  	put_parallel(par);
  	return PNFS_ATTEMPTED;
  
   use_mds:
  	dprintk("Giving up and using normal NFS
  ");

  	return PNFS_NOT_ATTEMPTED;
  }

  static void mark_extents_written(struct pnfs_block_layout *bl,
  				 __u64 offset, __u32 count)
  {
  	sector_t isect, end;
  	struct pnfs_block_extent *be;

  	struct pnfs_block_short_extent *se;

  
  	dprintk("%s(%llu, %u)
  ", __func__, offset, count);
  	if (count == 0)
  		return;
  	isect = (offset & (long)(PAGE_CACHE_MASK)) >> SECTOR_SHIFT;
  	end = (offset + count + PAGE_CACHE_SIZE - 1) & (long)(PAGE_CACHE_MASK);
  	end >>= SECTOR_SHIFT;
  	while (isect < end) {
  		sector_t len;
  		be = bl_find_get_extent(bl, isect, NULL);
  		BUG_ON(!be); /* FIXME */
  		len = min(end, be->be_f_offset + be->be_length) - isect;

  		if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
  			se = bl_pop_one_short_extent(be->be_inval);
  			BUG_ON(!se);
  			bl_mark_for_commit(be, isect, len, se);
  		}

  		isect += len;
  		bl_put_extent(be);
  	}
  }

  static void bl_end_io_write_zero(struct bio *bio, int err)
  {
  	struct parallel_io *par = bio->bi_private;
  	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
  	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
  	struct nfs_write_data *wdata = (struct nfs_write_data *)par->data;
  
  	do {
  		struct page *page = bvec->bv_page;
  
  		if (--bvec >= bio->bi_io_vec)
  			prefetchw(&bvec->bv_page->flags);
  		/* This is the zeroing page we added */
  		end_page_writeback(page);
  		page_cache_release(page);
  	} while (bvec >= bio->bi_io_vec);

  
  	if (unlikely(!uptodate)) {

  		if (!wdata->pnfs_error)
  			wdata->pnfs_error = -EIO;

  		pnfs_set_lo_fail(wdata->lseg);

  	}
  	bio_put(bio);
  	put_parallel(par);
  }

  static void bl_end_io_write(struct bio *bio, int err)
  {
  	struct parallel_io *par = bio->bi_private;
  	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
  	struct nfs_write_data *wdata = (struct nfs_write_data *)par->data;
  
  	if (!uptodate) {
  		if (!wdata->pnfs_error)
  			wdata->pnfs_error = -EIO;

  		pnfs_set_lo_fail(wdata->lseg);

  	}
  	bio_put(bio);
  	put_parallel(par);
  }
  
  /* Function scheduled for call during bl_end_par_io_write,
   * it marks sectors as written and extends the commitlist.
   */
  static void bl_write_cleanup(struct work_struct *work)
  {
  	struct rpc_task *task;
  	struct nfs_write_data *wdata;
  	dprintk("%s enter
  ", __func__);
  	task = container_of(work, struct rpc_task, u.tk_work);
  	wdata = container_of(task, struct nfs_write_data, task);

  	if (likely(!wdata->pnfs_error)) {

  		/* Marks for LAYOUTCOMMIT */

  		mark_extents_written(BLK_LSEG2EXT(wdata->lseg),
  				     wdata->args.offset, wdata->args.count);
  	}

  	pnfs_ld_write_done(wdata);
  }
  
  /* Called when last of bios associated with a bl_write_pagelist call finishes */

  static void bl_end_par_io_write(void *data, int num_se)

  {
  	struct nfs_write_data *wdata = data;

  	if (unlikely(wdata->pnfs_error)) {
  		bl_free_short_extents(&BLK_LSEG2EXT(wdata->lseg)->bl_inval,
  					num_se);
  	}

  	wdata->task.tk_status = wdata->pnfs_error;

  	wdata->verf.committed = NFS_FILE_SYNC;
  	INIT_WORK(&wdata->task.u.tk_work, bl_write_cleanup);
  	schedule_work(&wdata->task.u.tk_work);
  }

  /* FIXME STUB - mark intersection of layout and page as bad, so is not
   * used again.
   */
  static void mark_bad_read(void)
  {
  	return;
  }
  
  /*
   * map_block:  map a requested I/0 block (isect) into an offset in the LVM
   * block_device
   */
  static void
  map_block(struct buffer_head *bh, sector_t isect, struct pnfs_block_extent *be)
  {
  	dprintk("%s enter be=%p
  ", __func__, be);
  
  	set_buffer_mapped(bh);
  	bh->b_bdev = be->be_mdev;
  	bh->b_blocknr = (isect - be->be_f_offset + be->be_v_offset) >>
  	    (be->be_mdev->bd_inode->i_blkbits - SECTOR_SHIFT);
  
  	dprintk("%s isect %llu, bh->b_blocknr %ld, using bsize %Zd
  ",
  		__func__, (unsigned long long)isect, (long)bh->b_blocknr,
  		bh->b_size);
  	return;
  }
  
  /* Given an unmapped page, zero it or read in page for COW, page is locked
   * by caller.
   */
  static int
  init_page_for_write(struct page *page, struct pnfs_block_extent *cow_read)
  {
  	struct buffer_head *bh = NULL;
  	int ret = 0;
  	sector_t isect;
  
  	dprintk("%s enter, %p
  ", __func__, page);
  	BUG_ON(PageUptodate(page));
  	if (!cow_read) {
  		zero_user_segment(page, 0, PAGE_SIZE);
  		SetPageUptodate(page);
  		goto cleanup;
  	}
  
  	bh = alloc_page_buffers(page, PAGE_CACHE_SIZE, 0);
  	if (!bh) {
  		ret = -ENOMEM;
  		goto cleanup;
  	}
  
  	isect = (sector_t) page->index << PAGE_CACHE_SECTOR_SHIFT;
  	map_block(bh, isect, cow_read);
  	if (!bh_uptodate_or_lock(bh))
  		ret = bh_submit_read(bh);
  	if (ret)
  		goto cleanup;
  	SetPageUptodate(page);
  
  cleanup:
  	bl_put_extent(cow_read);
  	if (bh)
  		free_buffer_head(bh);
  	if (ret) {
  		/* Need to mark layout with bad read...should now
  		 * just use nfs4 for reads and writes.
  		 */
  		mark_bad_read();
  	}
  	return ret;
  }

  /* Find or create a zeroing page marked being writeback.
   * Return ERR_PTR on error, NULL to indicate skip this page and page itself
   * to indicate write out.
   */
  static struct page *
  bl_find_get_zeroing_page(struct inode *inode, pgoff_t index,
  			struct pnfs_block_extent *cow_read)
  {
  	struct page *page;
  	int locked = 0;
  	page = find_get_page(inode->i_mapping, index);
  	if (page)
  		goto check_page;
  
  	page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
  	if (unlikely(!page)) {
  		dprintk("%s oom
  ", __func__);
  		return ERR_PTR(-ENOMEM);
  	}
  	locked = 1;
  
  check_page:
  	/* PageDirty: Other will write this out
  	 * PageWriteback: Other is writing this out
  	 * PageUptodate: It was read before
  	 */
  	if (PageDirty(page) || PageWriteback(page)) {
  		print_page(page);
  		if (locked)
  			unlock_page(page);
  		page_cache_release(page);
  		return NULL;
  	}
  
  	if (!locked) {
  		lock_page(page);
  		locked = 1;
  		goto check_page;
  	}
  	if (!PageUptodate(page)) {
  		/* New page, readin or zero it */
  		init_page_for_write(page, cow_read);
  	}
  	set_page_writeback(page);
  	unlock_page(page);
  
  	return page;
  }

  static enum pnfs_try_status

  bl_write_pagelist(struct nfs_write_data *wdata, int sync)

  {

  	int i, ret, npg_zero, pg_index, last = 0;

  	struct bio *bio = NULL;

  	struct pnfs_block_extent *be = NULL, *cow_read = NULL;
  	sector_t isect, last_isect = 0, extent_length = 0;

  	struct parallel_io *par;
  	loff_t offset = wdata->args.offset;
  	size_t count = wdata->args.count;
  	struct page **pages = wdata->args.pages;

  	struct page *page;
  	pgoff_t index;
  	u64 temp;
  	int npg_per_block =
  	    NFS_SERVER(wdata->inode)->pnfs_blksize >> PAGE_CACHE_SHIFT;

  
  	dprintk("%s enter, %Zu@%lld
  ", __func__, count, offset);
  	/* At this point, wdata->pages is a (sequential) list of nfs_pages.

  	 * We want to write each, and if there is an error set pnfs_error
  	 * to have it redone using nfs.

  	 */
  	par = alloc_parallel(wdata);
  	if (!par)

  		goto out_mds;

  	par->pnfs_callback = bl_end_par_io_write;
  	/* At this point, have to be more careful with error handling */
  
  	isect = (sector_t) ((offset & (long)PAGE_CACHE_MASK) >> SECTOR_SHIFT);

  	be = bl_find_get_extent(BLK_LSEG2EXT(wdata->lseg), isect, &cow_read);
  	if (!be || !is_writable(be, isect)) {
  		dprintk("%s no matching extents!
  ", __func__);

  		goto out_mds;

  	}
  
  	/* First page inside INVALID extent */
  	if (be->be_state == PNFS_BLOCK_INVALID_DATA) {

  		if (likely(!bl_push_one_short_extent(be->be_inval)))
  			par->bse_count++;
  		else
  			goto out_mds;

  		temp = offset >> PAGE_CACHE_SHIFT;
  		npg_zero = do_div(temp, npg_per_block);
  		isect = (sector_t) (((offset - npg_zero * PAGE_CACHE_SIZE) &
  				     (long)PAGE_CACHE_MASK) >> SECTOR_SHIFT);
  		extent_length = be->be_length - (isect - be->be_f_offset);
  
  fill_invalid_ext:
  		dprintk("%s need to zero %d pages
  ", __func__, npg_zero);
  		for (;npg_zero > 0; npg_zero--) {

  			if (bl_is_sector_init(be->be_inval, isect)) {
  				dprintk("isect %llu already init
  ",
  					(unsigned long long)isect);
  				goto next_page;
  			}

  			/* page ref released in bl_end_io_write_zero */
  			index = isect >> PAGE_CACHE_SECTOR_SHIFT;
  			dprintk("%s zero %dth page: index %lu isect %llu
  ",
  				__func__, npg_zero, index,
  				(unsigned long long)isect);

  			page = bl_find_get_zeroing_page(wdata->inode, index,
  							cow_read);
  			if (unlikely(IS_ERR(page))) {
  				wdata->pnfs_error = PTR_ERR(page);

  				goto out;

  			} else if (page == NULL)

  				goto next_page;

  
  			ret = bl_mark_sectors_init(be->be_inval, isect,

  						       PAGE_CACHE_SECTORS);

  			if (unlikely(ret)) {
  				dprintk("%s bl_mark_sectors_init fail %d
  ",
  					__func__, ret);
  				end_page_writeback(page);
  				page_cache_release(page);
  				wdata->pnfs_error = ret;
  				goto out;
  			}

  			if (likely(!bl_push_one_short_extent(be->be_inval)))
  				par->bse_count++;
  			else {
  				end_page_writeback(page);
  				page_cache_release(page);
  				wdata->pnfs_error = -ENOMEM;
  				goto out;
  			}
  			/* FIXME: This should be done in bi_end_io */
  			mark_extents_written(BLK_LSEG2EXT(wdata->lseg),
  					     page->index << PAGE_CACHE_SHIFT,
  					     PAGE_CACHE_SIZE);

  			bio = bl_add_page_to_bio(bio, npg_zero, WRITE,
  						 isect, page, be,
  						 bl_end_io_write_zero, par);
  			if (IS_ERR(bio)) {
  				wdata->pnfs_error = PTR_ERR(bio);

  				bio = NULL;

  				goto out;
  			}

  next_page:
  			isect += PAGE_CACHE_SECTORS;
  			extent_length -= PAGE_CACHE_SECTORS;
  		}
  		if (last)
  			goto write_done;
  	}
  	bio = bl_submit_bio(WRITE, bio);
  
  	/* Middle pages */
  	pg_index = wdata->args.pgbase >> PAGE_CACHE_SHIFT;
  	for (i = pg_index; i < wdata->npages; i++) {

  		if (!extent_length) {
  			/* We've used up the previous extent */
  			bl_put_extent(be);
  			bio = bl_submit_bio(WRITE, bio);
  			/* Get the next one */
  			be = bl_find_get_extent(BLK_LSEG2EXT(wdata->lseg),
  					     isect, NULL);
  			if (!be || !is_writable(be, isect)) {

  				wdata->pnfs_error = -EINVAL;

  				goto out;
  			}

  			if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
  				if (likely(!bl_push_one_short_extent(
  								be->be_inval)))
  					par->bse_count++;
  				else {
  					wdata->pnfs_error = -ENOMEM;
  					goto out;
  				}
  			}

  			extent_length = be->be_length -

  			    (isect - be->be_f_offset);

  		}

  		if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
  			ret = bl_mark_sectors_init(be->be_inval, isect,

  						       PAGE_CACHE_SECTORS);

  			if (unlikely(ret)) {
  				dprintk("%s bl_mark_sectors_init fail %d
  ",
  					__func__, ret);
  				wdata->pnfs_error = ret;
  				goto out;

  			}

  		}
  		bio = bl_add_page_to_bio(bio, wdata->npages - i, WRITE,
  					 isect, pages[i], be,
  					 bl_end_io_write, par);
  		if (IS_ERR(bio)) {
  			wdata->pnfs_error = PTR_ERR(bio);

  			bio = NULL;

  			goto out;

  		}
  		isect += PAGE_CACHE_SECTORS;

  		last_isect = isect;

  		extent_length -= PAGE_CACHE_SECTORS;
  	}

  
  	/* Last page inside INVALID extent */
  	if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
  		bio = bl_submit_bio(WRITE, bio);
  		temp = last_isect >> PAGE_CACHE_SECTOR_SHIFT;
  		npg_zero = npg_per_block - do_div(temp, npg_per_block);
  		if (npg_zero < npg_per_block) {
  			last = 1;
  			goto fill_invalid_ext;
  		}
  	}
  
  write_done:
  	wdata->res.count = (last_isect << SECTOR_SHIFT) - (offset);
  	if (count < wdata->res.count) {

  		wdata->res.count = count;

  	}

  out:
  	bl_put_extent(be);
  	bl_submit_bio(WRITE, bio);
  	put_parallel(par);
  	return PNFS_ATTEMPTED;

  out_mds:
  	bl_put_extent(be);
  	kfree(par);
  	return PNFS_NOT_ATTEMPTED;

  }

  /* FIXME - range ignored */

  static void

  release_extents(struct pnfs_block_layout *bl, struct pnfs_layout_range *range)

  {

  	int i;
  	struct pnfs_block_extent *be;
  
  	spin_lock(&bl->bl_ext_lock);
  	for (i = 0; i < EXTENT_LISTS; i++) {
  		while (!list_empty(&bl->bl_extents[i])) {
  			be = list_first_entry(&bl->bl_extents[i],
  					      struct pnfs_block_extent,
  					      be_node);
  			list_del(&be->be_node);
  			bl_put_extent(be);
  		}
  	}
  	spin_unlock(&bl->bl_ext_lock);

  }

  static void
  release_inval_marks(struct pnfs_inval_markings *marks)
  {

  	struct pnfs_inval_tracking *pos, *temp;

  	struct pnfs_block_short_extent *se, *stemp;

  
  	list_for_each_entry_safe(pos, temp, &marks->im_tree.mtt_stub, it_link) {
  		list_del(&pos->it_link);
  		kfree(pos);
  	}

  
  	list_for_each_entry_safe(se, stemp, &marks->im_extents, bse_node) {
  		list_del(&se->bse_node);
  		kfree(se);
  	}

  	return;
  }
  
  static void bl_free_layout_hdr(struct pnfs_layout_hdr *lo)
  {
  	struct pnfs_block_layout *bl = BLK_LO2EXT(lo);
  
  	dprintk("%s enter
  ", __func__);
  	release_extents(bl, NULL);
  	release_inval_marks(&bl->bl_inval);
  	kfree(bl);
  }
  
  static struct pnfs_layout_hdr *bl_alloc_layout_hdr(struct inode *inode,
  						   gfp_t gfp_flags)
  {
  	struct pnfs_block_layout *bl;
  
  	dprintk("%s enter
  ", __func__);
  	bl = kzalloc(sizeof(*bl), gfp_flags);
  	if (!bl)
  		return NULL;
  	spin_lock_init(&bl->bl_ext_lock);
  	INIT_LIST_HEAD(&bl->bl_extents[0]);
  	INIT_LIST_HEAD(&bl->bl_extents[1]);
  	INIT_LIST_HEAD(&bl->bl_commit);
  	INIT_LIST_HEAD(&bl->bl_committing);
  	bl->bl_count = 0;
  	bl->bl_blocksize = NFS_SERVER(inode)->pnfs_blksize >> SECTOR_SHIFT;
  	BL_INIT_INVAL_MARKS(&bl->bl_inval, bl->bl_blocksize);
  	return &bl->bl_layout;
  }

  static void bl_free_lseg(struct pnfs_layout_segment *lseg)

  {

  	dprintk("%s enter
  ", __func__);
  	kfree(lseg);

  }

  /* We pretty much ignore lseg, and store all data layout wide, so we
   * can correctly merge.
   */
  static struct pnfs_layout_segment *bl_alloc_lseg(struct pnfs_layout_hdr *lo,
  						 struct nfs4_layoutget_res *lgr,
  						 gfp_t gfp_flags)

  {

  	struct pnfs_layout_segment *lseg;
  	int status;
  
  	dprintk("%s enter
  ", __func__);
  	lseg = kzalloc(sizeof(*lseg), gfp_flags);
  	if (!lseg)
  		return ERR_PTR(-ENOMEM);
  	status = nfs4_blk_process_layoutget(lo, lgr, gfp_flags);
  	if (status) {
  		/* We don't want to call the full-blown bl_free_lseg,
  		 * since on error extents were not touched.
  		 */
  		kfree(lseg);
  		return ERR_PTR(status);
  	}
  	return lseg;

  }
  
  static void
  bl_encode_layoutcommit(struct pnfs_layout_hdr *lo, struct xdr_stream *xdr,
  		       const struct nfs4_layoutcommit_args *arg)
  {

  	dprintk("%s enter
  ", __func__);
  	encode_pnfs_block_layoutupdate(BLK_LO2EXT(lo), xdr, arg);

  }
  
  static void
  bl_cleanup_layoutcommit(struct nfs4_layoutcommit_data *lcdata)
  {

  	struct pnfs_layout_hdr *lo = NFS_I(lcdata->args.inode)->layout;
  
  	dprintk("%s enter
  ", __func__);
  	clean_pnfs_block_layoutupdate(BLK_LO2EXT(lo), &lcdata->args, lcdata->res.status);

  }

  static void free_blk_mountid(struct block_mount_id *mid)
  {
  	if (mid) {

  		struct pnfs_block_dev *dev, *tmp;
  
  		/* No need to take bm_lock as we are last user freeing bm_devlist */
  		list_for_each_entry_safe(dev, tmp, &mid->bm_devlist, bm_node) {

  			list_del(&dev->bm_node);
  			bl_free_block_dev(dev);
  		}

  		kfree(mid);
  	}
  }
  
  /* This is mostly copied from the filelayout's get_device_info function.
   * It seems much of this should be at the generic pnfs level.
   */
  static struct pnfs_block_dev *
  nfs4_blk_get_deviceinfo(struct nfs_server *server, const struct nfs_fh *fh,
  			struct nfs4_deviceid *d_id)
  {
  	struct pnfs_device *dev;

  	struct pnfs_block_dev *rv;

  	u32 max_resp_sz;
  	int max_pages;
  	struct page **pages = NULL;
  	int i, rc;
  
  	/*
  	 * Use the session max response size as the basis for setting
  	 * GETDEVICEINFO's maxcount
  	 */
  	max_resp_sz = server->nfs_client->cl_session->fc_attrs.max_resp_sz;
  	max_pages = max_resp_sz >> PAGE_SHIFT;
  	dprintk("%s max_resp_sz %u max_pages %d
  ",
  		__func__, max_resp_sz, max_pages);
  
  	dev = kmalloc(sizeof(*dev), GFP_NOFS);
  	if (!dev) {
  		dprintk("%s kmalloc failed
  ", __func__);

  		return ERR_PTR(-ENOMEM);

  	}
  
  	pages = kzalloc(max_pages * sizeof(struct page *), GFP_NOFS);
  	if (pages == NULL) {
  		kfree(dev);

  		return ERR_PTR(-ENOMEM);

  	}
  	for (i = 0; i < max_pages; i++) {
  		pages[i] = alloc_page(GFP_NOFS);

  		if (!pages[i]) {
  			rv = ERR_PTR(-ENOMEM);

  			goto out_free;

  		}

  	}
  
  	memcpy(&dev->dev_id, d_id, sizeof(*d_id));
  	dev->layout_type = LAYOUT_BLOCK_VOLUME;
  	dev->pages = pages;
  	dev->pgbase = 0;
  	dev->pglen = PAGE_SIZE * max_pages;
  	dev->mincount = 0;
  
  	dprintk("%s: dev_id: %s
  ", __func__, dev->dev_id.data);
  	rc = nfs4_proc_getdeviceinfo(server, dev);
  	dprintk("%s getdevice info returns %d
  ", __func__, rc);

  	if (rc) {
  		rv = ERR_PTR(rc);

  		goto out_free;

  	}

  
  	rv = nfs4_blk_decode_device(server, dev);
   out_free:
  	for (i = 0; i < max_pages; i++)
  		__free_page(pages[i]);
  	kfree(pages);
  	kfree(dev);
  	return rv;
  }

  static int
  bl_set_layoutdriver(struct nfs_server *server, const struct nfs_fh *fh)
  {

  	struct block_mount_id *b_mt_id = NULL;
  	struct pnfs_devicelist *dlist = NULL;
  	struct pnfs_block_dev *bdev;
  	LIST_HEAD(block_disklist);

  	int status, i;

  	dprintk("%s enter
  ", __func__);

  
  	if (server->pnfs_blksize == 0) {
  		dprintk("%s Server did not return blksize
  ", __func__);
  		return -EINVAL;
  	}
  	b_mt_id = kzalloc(sizeof(struct block_mount_id), GFP_NOFS);
  	if (!b_mt_id) {
  		status = -ENOMEM;
  		goto out_error;
  	}
  	/* Initialize nfs4 block layout mount id */
  	spin_lock_init(&b_mt_id->bm_lock);
  	INIT_LIST_HEAD(&b_mt_id->bm_devlist);
  
  	dlist = kmalloc(sizeof(struct pnfs_devicelist), GFP_NOFS);
  	if (!dlist) {
  		status = -ENOMEM;
  		goto out_error;
  	}
  	dlist->eof = 0;
  	while (!dlist->eof) {
  		status = nfs4_proc_getdevicelist(server, fh, dlist);
  		if (status)
  			goto out_error;
  		dprintk("%s GETDEVICELIST numdevs=%i, eof=%i
  ",
  			__func__, dlist->num_devs, dlist->eof);
  		for (i = 0; i < dlist->num_devs; i++) {
  			bdev = nfs4_blk_get_deviceinfo(server, fh,
  						       &dlist->dev_id[i]);

  			if (IS_ERR(bdev)) {
  				status = PTR_ERR(bdev);

  				goto out_error;
  			}
  			spin_lock(&b_mt_id->bm_lock);
  			list_add(&bdev->bm_node, &b_mt_id->bm_devlist);
  			spin_unlock(&b_mt_id->bm_lock);
  		}
  	}
  	dprintk("%s SUCCESS
  ", __func__);
  	server->pnfs_ld_data = b_mt_id;
  
   out_return:
  	kfree(dlist);
  	return status;
  
   out_error:
  	free_blk_mountid(b_mt_id);
  	goto out_return;

  }
  
  static int
  bl_clear_layoutdriver(struct nfs_server *server)
  {

  	struct block_mount_id *b_mt_id = server->pnfs_ld_data;

  	dprintk("%s enter
  ", __func__);

  	free_blk_mountid(b_mt_id);
  	dprintk("%s RETURNS
  ", __func__);

  	return 0;
  }

  static const struct nfs_pageio_ops bl_pg_read_ops = {
  	.pg_init = pnfs_generic_pg_init_read,
  	.pg_test = pnfs_generic_pg_test,
  	.pg_doio = pnfs_generic_pg_readpages,
  };
  
  static const struct nfs_pageio_ops bl_pg_write_ops = {
  	.pg_init = pnfs_generic_pg_init_write,
  	.pg_test = pnfs_generic_pg_test,
  	.pg_doio = pnfs_generic_pg_writepages,
  };

  static struct pnfs_layoutdriver_type blocklayout_type = {
  	.id				= LAYOUT_BLOCK_VOLUME,
  	.name				= "LAYOUT_BLOCK_VOLUME",
  	.read_pagelist			= bl_read_pagelist,
  	.write_pagelist			= bl_write_pagelist,
  	.alloc_layout_hdr		= bl_alloc_layout_hdr,
  	.free_layout_hdr		= bl_free_layout_hdr,
  	.alloc_lseg			= bl_alloc_lseg,
  	.free_lseg			= bl_free_lseg,
  	.encode_layoutcommit		= bl_encode_layoutcommit,
  	.cleanup_layoutcommit		= bl_cleanup_layoutcommit,
  	.set_layoutdriver		= bl_set_layoutdriver,
  	.clear_layoutdriver		= bl_clear_layoutdriver,

  	.pg_read_ops			= &bl_pg_read_ops,
  	.pg_write_ops			= &bl_pg_write_ops,

  };

  static const struct rpc_pipe_ops bl_upcall_ops = {

  	.upcall		= rpc_pipe_generic_upcall,

  	.downcall	= bl_pipe_downcall,
  	.destroy_msg	= bl_pipe_destroy_msg,
  };

  static int __init nfs4blocklayout_init(void)
  {

  	struct vfsmount *mnt;
  	struct path path;

  	int ret;
  
  	dprintk("%s: NFSv4 Block Layout Driver Registering...
  ", __func__);
  
  	ret = pnfs_register_layoutdriver(&blocklayout_type);

  	if (ret)
  		goto out;
  
  	init_waitqueue_head(&bl_wq);
  
  	mnt = rpc_get_mount();
  	if (IS_ERR(mnt)) {
  		ret = PTR_ERR(mnt);
  		goto out_remove;
  	}
  
  	ret = vfs_path_lookup(mnt->mnt_root,
  			      mnt,
  			      NFS_PIPE_DIRNAME, 0, &path);
  	if (ret)

  		goto out_putrpc;

  
  	bl_device_pipe = rpc_mkpipe(path.dentry, "blocklayout", NULL,
  				    &bl_upcall_ops, 0);

  	path_put(&path);

  	if (IS_ERR(bl_device_pipe)) {
  		ret = PTR_ERR(bl_device_pipe);

  		goto out_putrpc;

  	}
  out:
  	return ret;

  out_putrpc:
  	rpc_put_mount();

  out_remove:
  	pnfs_unregister_layoutdriver(&blocklayout_type);

  	return ret;
  }
  
  static void __exit nfs4blocklayout_exit(void)
  {
  	dprintk("%s: NFSv4 Block Layout Driver Unregistering...
  ",
  	       __func__);
  
  	pnfs_unregister_layoutdriver(&blocklayout_type);

  	rpc_unlink(bl_device_pipe);

  	rpc_put_mount();

  }
  
  MODULE_ALIAS("nfs-layouttype4-3");
  
  module_init(nfs4blocklayout_init);
  module_exit(nfs4blocklayout_exit);