/*
   *  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 <linux/pagevec.h>
  
  #include "../pnfs.h"
  #include "../nfs4session.h"
  #include "../internal.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");
  
  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_iter.bi_size,
  			(unsigned long long)bio->bi_iter.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_iter.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 *do_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,
  				      unsigned int offset, int len)
  {
  	isect = isect + (offset >> SECTOR_SHIFT);
  	dprintk("%s: npg %d rw %d isect %llu offset %u len %d
  ", __func__,
  		npg, rw, (unsigned long long)isect, offset, len);
  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, len, offset) < len) {
  		bio = bl_submit_bio(rw, bio);
  		goto retry;
  	}
  	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)
  {
  	return do_add_page_to_bio(bio, npg, rw, isect, page, be,
  				  end_io, par, 0, PAGE_CACHE_SIZE);
  }
  
  /* 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;
  	struct bio_vec *bvec;
  	int i;
  
  	if (!err)
  		bio_for_each_segment_all(bvec, bio, i)
  			SetPageUptodate(bvec->bv_page);
  
  	if (err) {
  		struct nfs_read_data *rdata = par->data;
  		struct nfs_pgio_header *header = rdata->header;
  
  		if (!header->pnfs_error)
  			header->pnfs_error = -EIO;
  		pnfs_set_lo_fail(header->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->header->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)
  {
  	struct nfs_pgio_header *header = rdata->header;
  	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 bytes_left = rdata->args.count;
  	unsigned int pg_offset, pg_len;
  	struct page **pages = rdata->args.pages;
  	int pg_index = rdata->args.pgbase >> PAGE_CACHE_SHIFT;
  	const bool is_dio = (header->dreq != NULL);
  
  	dprintk("%s enter nr_pages %u offset %lld count %u
  ", __func__,
  	       rdata->pages.npages, f_offset, (unsigned int)rdata->args.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->pages.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(header->lseg),
  					     isect, &cow_read);
  			if (!be) {
  				header->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);
  			}
  		}
  
  		if (is_dio) {
  			pg_offset = f_offset & ~PAGE_CACHE_MASK;
  			if (pg_offset + bytes_left > PAGE_CACHE_SIZE)
  				pg_len = PAGE_CACHE_SIZE - pg_offset;
  			else
  				pg_len = bytes_left;
  
  			f_offset += pg_len;
  			bytes_left -= pg_len;
  			isect += (pg_offset >> SECTOR_SHIFT);
  		} else {
  			pg_offset = 0;
  			pg_len = PAGE_CACHE_SIZE;
  		}
  
  		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], pg_offset, pg_len);
  			print_page(pages[i]);
  			SetPageUptodate(pages[i]);
  		} else {
  			struct pnfs_block_extent *be_read;
  
  			be_read = (hole && cow_read) ? cow_read : be;
  			bio = do_add_page_to_bio(bio, rdata->pages.npages - i,
  						 READ,
  						 isect, pages[i], be_read,
  						 bl_end_io_read, par,
  						 pg_offset, pg_len);
  			if (IS_ERR(bio)) {
  				header->pnfs_error = PTR_ERR(bio);
  				bio = NULL;
  				goto out;
  			}
  		}
  		isect += (pg_len >> SECTOR_SHIFT);
  		extent_length -= PAGE_CACHE_SECTORS;
  	}
  	if ((isect << SECTOR_SHIFT) >= header->inode->i_size) {
  		rdata->res.eof = 1;
  		rdata->res.count = header->inode->i_size - rdata->args.offset;
  	} else {
  		rdata->res.count = (isect << SECTOR_SHIFT) - rdata->args.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;
  	struct bio_vec *bvec;
  	int i;
  
  	bio_for_each_segment_all(bvec, bio, i) {
  		/* This is the zeroing page we added */
  		end_page_writeback(bvec->bv_page);
  		page_cache_release(bvec->bv_page);
  	}
  
  	if (unlikely(err)) {
  		struct nfs_write_data *data = par->data;
  		struct nfs_pgio_header *header = data->header;
  
  		if (!header->pnfs_error)
  			header->pnfs_error = -EIO;
  		pnfs_set_lo_fail(header->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 *data = par->data;
  	struct nfs_pgio_header *header = data->header;
  
  	if (!uptodate) {
  		if (!header->pnfs_error)
  			header->pnfs_error = -EIO;
  		pnfs_set_lo_fail(header->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->header->pnfs_error)) {
  		/* Marks for LAYOUTCOMMIT */
  		mark_extents_written(BLK_LSEG2EXT(wdata->header->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->header->pnfs_error)) {
  		bl_free_short_extents(&BLK_LSEG2EXT(wdata->header->lseg)->bl_inval,
  					num_se);
  	}
  
  	wdata->task.tk_status = wdata->header->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;
  }
  
  static void
  bl_read_single_end_io(struct bio *bio, int error)
  {
  	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
  	struct page *page = bvec->bv_page;
  
  	/* Only one page in bvec */
  	unlock_page(page);
  }
  
  static int
  bl_do_readpage_sync(struct page *page, struct pnfs_block_extent *be,
  		    unsigned int offset, unsigned int len)
  {
  	struct bio *bio;
  	struct page *shadow_page;
  	sector_t isect;
  	char *kaddr, *kshadow_addr;
  	int ret = 0;
  
  	dprintk("%s: offset %u len %u
  ", __func__, offset, len);
  
  	shadow_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
  	if (shadow_page == NULL)
  		return -ENOMEM;
  
  	bio = bio_alloc(GFP_NOIO, 1);
  	if (bio == NULL)
  		return -ENOMEM;
  
  	isect = (page->index << PAGE_CACHE_SECTOR_SHIFT) +
  		(offset / SECTOR_SIZE);
  
  	bio->bi_iter.bi_sector = isect - be->be_f_offset + be->be_v_offset;
  	bio->bi_bdev = be->be_mdev;
  	bio->bi_end_io = bl_read_single_end_io;
  
  	lock_page(shadow_page);
  	if (bio_add_page(bio, shadow_page,
  			 SECTOR_SIZE, round_down(offset, SECTOR_SIZE)) == 0) {
  		unlock_page(shadow_page);
  		bio_put(bio);
  		return -EIO;
  	}
  
  	submit_bio(READ, bio);
  	wait_on_page_locked(shadow_page);
  	if (unlikely(!test_bit(BIO_UPTODATE, &bio->bi_flags))) {
  		ret = -EIO;
  	} else {
  		kaddr = kmap_atomic(page);
  		kshadow_addr = kmap_atomic(shadow_page);
  		memcpy(kaddr + offset, kshadow_addr + offset, len);
  		kunmap_atomic(kshadow_addr);
  		kunmap_atomic(kaddr);
  	}
  	__free_page(shadow_page);
  	bio_put(bio);
  
  	return ret;
  }
  
  static int
  bl_read_partial_page_sync(struct page *page, struct pnfs_block_extent *be,
  			  unsigned int dirty_offset, unsigned int dirty_len,
  			  bool full_page)
  {
  	int ret = 0;
  	unsigned int start, end;
  
  	if (full_page) {
  		start = 0;
  		end = PAGE_CACHE_SIZE;
  	} else {
  		start = round_down(dirty_offset, SECTOR_SIZE);
  		end = round_up(dirty_offset + dirty_len, SECTOR_SIZE);
  	}
  
  	dprintk("%s: offset %u len %d
  ", __func__, dirty_offset, dirty_len);
  	if (!be) {
  		zero_user_segments(page, start, dirty_offset,
  				   dirty_offset + dirty_len, end);
  		if (start == 0 && end == PAGE_CACHE_SIZE &&
  		    trylock_page(page)) {
  			SetPageUptodate(page);
  			unlock_page(page);
  		}
  		return ret;
  	}
  
  	if (start != dirty_offset)
  		ret = bl_do_readpage_sync(page, be, start, dirty_offset - start);
  
  	if (!ret && (dirty_offset + dirty_len < end))
  		ret = bl_do_readpage_sync(page, be, dirty_offset + dirty_len,
  					  end - dirty_offset - dirty_len);
  
  	return ret;
  }
  
  /* 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:
  	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)
  {
  	struct nfs_pgio_header *header = wdata->header;
  	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 = NULL;
  	loff_t offset = wdata->args.offset;
  	size_t count = wdata->args.count;
  	unsigned int pg_offset, pg_len, saved_len;
  	struct page **pages = wdata->args.pages;
  	struct page *page;
  	pgoff_t index;
  	u64 temp;
  	int npg_per_block =
  	    NFS_SERVER(header->inode)->pnfs_blksize >> PAGE_CACHE_SHIFT;
  
  	dprintk("%s enter, %Zu@%lld
  ", __func__, count, offset);
  
  	if (header->dreq != NULL &&
  	    (!IS_ALIGNED(offset, NFS_SERVER(header->inode)->pnfs_blksize) ||
  	     !IS_ALIGNED(count, NFS_SERVER(header->inode)->pnfs_blksize))) {
  		dprintk("pnfsblock nonblock aligned DIO writes. Resend MDS
  ");
  		goto out_mds;
  	}
  	/* 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(header->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(header->inode, index,
  							cow_read);
  			if (unlikely(IS_ERR(page))) {
  				header->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);
  				header->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);
  				header->pnfs_error = -ENOMEM;
  				goto out;
  			}
  			/* FIXME: This should be done in bi_end_io */
  			mark_extents_written(BLK_LSEG2EXT(header->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)) {
  				header->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->pages.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(WRITE, bio);
  			/* Get the next one */
  			be = bl_find_get_extent(BLK_LSEG2EXT(header->lseg),
  					     isect, &cow_read);
  			if (!be || !is_writable(be, isect)) {
  				header->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 {
  					header->pnfs_error = -ENOMEM;
  					goto out;
  				}
  			}
  			extent_length = be->be_length -
  			    (isect - be->be_f_offset);
  		}
  
  		dprintk("%s offset %lld count %Zu
  ", __func__, offset, count);
  		pg_offset = offset & ~PAGE_CACHE_MASK;
  		if (pg_offset + count > PAGE_CACHE_SIZE)
  			pg_len = PAGE_CACHE_SIZE - pg_offset;
  		else
  			pg_len = count;
  
  		saved_len = pg_len;
  		if (be->be_state == PNFS_BLOCK_INVALID_DATA &&
  		    !bl_is_sector_init(be->be_inval, isect)) {
  			ret = bl_read_partial_page_sync(pages[i], cow_read,
  							pg_offset, pg_len, true);
  			if (ret) {
  				dprintk("%s bl_read_partial_page_sync fail %d
  ",
  					__func__, ret);
  				header->pnfs_error = ret;
  				goto out;
  			}
  
  			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);
  				header->pnfs_error = ret;
  				goto out;
  			}
  
  			/* Expand to full page write */
  			pg_offset = 0;
  			pg_len = PAGE_CACHE_SIZE;
  		} else if  ((pg_offset & (SECTOR_SIZE - 1)) ||
  			    (pg_len & (SECTOR_SIZE - 1))){
  			/* ahh, nasty case. We have to do sync full sector
  			 * read-modify-write cycles.
  			 */
  			unsigned int saved_offset = pg_offset;
  			ret = bl_read_partial_page_sync(pages[i], be, pg_offset,
  							pg_len, false);
  			pg_offset = round_down(pg_offset, SECTOR_SIZE);
  			pg_len = round_up(saved_offset + pg_len, SECTOR_SIZE)
  				 - pg_offset;
  		}
  
  
  		bio = do_add_page_to_bio(bio, wdata->pages.npages - i, WRITE,
  					 isect, pages[i], be,
  					 bl_end_io_write, par,
  					 pg_offset, pg_len);
  		if (IS_ERR(bio)) {
  			header->pnfs_error = PTR_ERR(bio);
  			bio = NULL;
  			goto out;
  		}
  		offset += saved_len;
  		count -= saved_len;
  		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 = wdata->args.count;
  out:
  	bl_put_extent(be);
  	bl_put_extent(cow_read);
  	bl_submit_bio(WRITE, bio);
  	put_parallel(par);
  	return PNFS_ATTEMPTED;
  out_mds:
  	bl_put_extent(be);
  	bl_put_extent(cow_read);
  	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_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 = nfs_page_array_len(0, max_resp_sz);
  	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;
  	dev->maxcount = max_resp_sz - nfs41_maxgetdevinfo_overhead;
  
  	dprintk("%s: dev_id: %s
  ", __func__, dev->dev_id.data);
  	rc = nfs4_proc_getdeviceinfo(server, dev, NULL);
  	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 bool
  is_aligned_req(struct nfs_page *req, unsigned int alignment)
  {
  	return IS_ALIGNED(req->wb_offset, alignment) &&
  	       IS_ALIGNED(req->wb_bytes, alignment);
  }
  
  static void
  bl_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
  {
  	if (pgio->pg_dreq != NULL &&
  	    !is_aligned_req(req, SECTOR_SIZE))
  		nfs_pageio_reset_read_mds(pgio);
  	else
  		pnfs_generic_pg_init_read(pgio, req);
  }
  
  static bool
  bl_pg_test_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
  		struct nfs_page *req)
  {
  	if (pgio->pg_dreq != NULL &&
  	    !is_aligned_req(req, SECTOR_SIZE))
  		return false;
  
  	return pnfs_generic_pg_test(pgio, prev, req);
  }
  
  /*
   * Return the number of contiguous bytes for a given inode
   * starting at page frame idx.
   */
  static u64 pnfs_num_cont_bytes(struct inode *inode, pgoff_t idx)
  {
  	struct address_space *mapping = inode->i_mapping;
  	pgoff_t end;
  
  	/* Optimize common case that writes from 0 to end of file */
  	end = DIV_ROUND_UP(i_size_read(inode), PAGE_CACHE_SIZE);
  	if (end != NFS_I(inode)->npages) {
  		rcu_read_lock();
  		end = page_cache_next_hole(mapping, idx + 1, ULONG_MAX);
  		rcu_read_unlock();
  	}
  
  	if (!end)
  		return i_size_read(inode) - (idx << PAGE_CACHE_SHIFT);
  	else
  		return (end - idx) << PAGE_CACHE_SHIFT;
  }
  
  static void
  bl_pg_init_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
  {
  	if (pgio->pg_dreq != NULL &&
  	    !is_aligned_req(req, PAGE_CACHE_SIZE)) {
  		nfs_pageio_reset_write_mds(pgio);
  	} else {
  		u64 wb_size;
  		if (pgio->pg_dreq == NULL)
  			wb_size = pnfs_num_cont_bytes(pgio->pg_inode,
  						      req->wb_index);
  		else
  			wb_size = nfs_dreq_bytes_left(pgio->pg_dreq);
  
  		pnfs_generic_pg_init_write(pgio, req, wb_size);
  	}
  }
  
  static bool
  bl_pg_test_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
  		 struct nfs_page *req)
  {
  	if (pgio->pg_dreq != NULL &&
  	    !is_aligned_req(req, PAGE_CACHE_SIZE))
  		return false;
  
  	return pnfs_generic_pg_test(pgio, prev, req);
  }
  
  static const struct nfs_pageio_ops bl_pg_read_ops = {
  	.pg_init = bl_pg_init_read,
  	.pg_test = bl_pg_test_read,
  	.pg_doio = pnfs_generic_pg_readpages,
  };
  
  static const struct nfs_pageio_ops bl_pg_write_ops = {
  	.pg_init = bl_pg_init_write,
  	.pg_test = bl_pg_test_write,
  	.pg_doio = pnfs_generic_pg_writepages,
  };
  
  static struct pnfs_layoutdriver_type blocklayout_type = {
  	.id				= LAYOUT_BLOCK_VOLUME,
  	.name				= "LAYOUT_BLOCK_VOLUME",
  	.owner				= THIS_MODULE,
  	.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 struct dentry *nfs4blocklayout_register_sb(struct super_block *sb,
  					    struct rpc_pipe *pipe)
  {
  	struct dentry *dir, *dentry;
  
  	dir = rpc_d_lookup_sb(sb, NFS_PIPE_DIRNAME);
  	if (dir == NULL)
  		return ERR_PTR(-ENOENT);
  	dentry = rpc_mkpipe_dentry(dir, "blocklayout", NULL, pipe);
  	dput(dir);
  	return dentry;
  }
  
  static void nfs4blocklayout_unregister_sb(struct super_block *sb,
  					  struct rpc_pipe *pipe)
  {
  	if (pipe->dentry)
  		rpc_unlink(pipe->dentry);
  }
  
  static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
  			   void *ptr)
  {
  	struct super_block *sb = ptr;
  	struct net *net = sb->s_fs_info;
  	struct nfs_net *nn = net_generic(net, nfs_net_id);
  	struct dentry *dentry;
  	int ret = 0;
  
  	if (!try_module_get(THIS_MODULE))
  		return 0;
  
  	if (nn->bl_device_pipe == NULL) {
  		module_put(THIS_MODULE);
  		return 0;
  	}
  
  	switch (event) {
  	case RPC_PIPEFS_MOUNT:
  		dentry = nfs4blocklayout_register_sb(sb, nn->bl_device_pipe);
  		if (IS_ERR(dentry)) {
  			ret = PTR_ERR(dentry);
  			break;
  		}
  		nn->bl_device_pipe->dentry = dentry;
  		break;
  	case RPC_PIPEFS_UMOUNT:
  		if (nn->bl_device_pipe->dentry)
  			nfs4blocklayout_unregister_sb(sb, nn->bl_device_pipe);
  		break;
  	default:
  		ret = -ENOTSUPP;
  		break;
  	}
  	module_put(THIS_MODULE);
  	return ret;
  }
  
  static struct notifier_block nfs4blocklayout_block = {
  	.notifier_call = rpc_pipefs_event,
  };
  
  static struct dentry *nfs4blocklayout_register_net(struct net *net,
  						   struct rpc_pipe *pipe)
  {
  	struct super_block *pipefs_sb;
  	struct dentry *dentry;
  
  	pipefs_sb = rpc_get_sb_net(net);
  	if (!pipefs_sb)
  		return NULL;
  	dentry = nfs4blocklayout_register_sb(pipefs_sb, pipe);
  	rpc_put_sb_net(net);
  	return dentry;
  }
  
  static void nfs4blocklayout_unregister_net(struct net *net,
  					   struct rpc_pipe *pipe)
  {
  	struct super_block *pipefs_sb;
  
  	pipefs_sb = rpc_get_sb_net(net);
  	if (pipefs_sb) {
  		nfs4blocklayout_unregister_sb(pipefs_sb, pipe);
  		rpc_put_sb_net(net);
  	}
  }
  
  static int nfs4blocklayout_net_init(struct net *net)
  {
  	struct nfs_net *nn = net_generic(net, nfs_net_id);
  	struct dentry *dentry;
  
  	init_waitqueue_head(&nn->bl_wq);
  	nn->bl_device_pipe = rpc_mkpipe_data(&bl_upcall_ops, 0);
  	if (IS_ERR(nn->bl_device_pipe))
  		return PTR_ERR(nn->bl_device_pipe);
  	dentry = nfs4blocklayout_register_net(net, nn->bl_device_pipe);
  	if (IS_ERR(dentry)) {
  		rpc_destroy_pipe_data(nn->bl_device_pipe);
  		return PTR_ERR(dentry);
  	}
  	nn->bl_device_pipe->dentry = dentry;
  	return 0;
  }
  
  static void nfs4blocklayout_net_exit(struct net *net)
  {
  	struct nfs_net *nn = net_generic(net, nfs_net_id);
  
  	nfs4blocklayout_unregister_net(net, nn->bl_device_pipe);
  	rpc_destroy_pipe_data(nn->bl_device_pipe);
  	nn->bl_device_pipe = NULL;
  }
  
  static struct pernet_operations nfs4blocklayout_net_ops = {
  	.init = nfs4blocklayout_net_init,
  	.exit = nfs4blocklayout_net_exit,
  };
  
  static int __init nfs4blocklayout_init(void)
  {
  	int ret;
  
  	dprintk("%s: NFSv4 Block Layout Driver Registering...
  ", __func__);
  
  	ret = pnfs_register_layoutdriver(&blocklayout_type);
  	if (ret)
  		goto out;
  
  	ret = rpc_pipefs_notifier_register(&nfs4blocklayout_block);
  	if (ret)
  		goto out_remove;
  	ret = register_pernet_subsys(&nfs4blocklayout_net_ops);
  	if (ret)
  		goto out_notifier;
  out:
  	return ret;
  
  out_notifier:
  	rpc_pipefs_notifier_unregister(&nfs4blocklayout_block);
  out_remove:
  	pnfs_unregister_layoutdriver(&blocklayout_type);
  	return ret;
  }
  
  static void __exit nfs4blocklayout_exit(void)
  {
  	dprintk("%s: NFSv4 Block Layout Driver Unregistering...
  ",
  	       __func__);
  
  	rpc_pipefs_notifier_unregister(&nfs4blocklayout_block);
  	unregister_pernet_subsys(&nfs4blocklayout_net_ops);
  	pnfs_unregister_layoutdriver(&blocklayout_type);
  }
  
  MODULE_ALIAS("nfs-layouttype4-3");
  
  module_init(nfs4blocklayout_init);
  module_exit(nfs4blocklayout_exit);