/*
   * Copyright (C) 2005, 2006

   * Avishay Traeger (avishay@gmail.com)

   * Copyright (C) 2008, 2009
   * Boaz Harrosh <bharrosh@panasas.com>
   *
   * Copyrights for code taken from ext2:
   *     Copyright (C) 1992, 1993, 1994, 1995
   *     Remy Card (card@masi.ibp.fr)
   *     Laboratoire MASI - Institut Blaise Pascal
   *     Universite Pierre et Marie Curie (Paris VI)
   *     from
   *     linux/fs/minix/inode.c
   *     Copyright (C) 1991, 1992  Linus Torvalds
   *
   * This file is part of exofs.
   *
   * exofs is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation.  Since it is based on ext2, and the only
   * valid version of GPL for the Linux kernel is version 2, the only valid
   * version of GPL for exofs is version 2.
   *
   * exofs 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 exofs; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */

  #include <linux/slab.h>

  
  #include "exofs.h"

  #define EXOFS_DBGMSG2(M...) do {} while (0)

  enum {MAX_PAGES_KMALLOC = PAGE_SIZE / sizeof(struct page *), };

  unsigned exofs_max_io_pages(struct ore_layout *layout,

  			    unsigned expected_pages)
  {
  	unsigned pages = min_t(unsigned, expected_pages, MAX_PAGES_KMALLOC);
  
  	/* TODO: easily support bio chaining */

  	pages =  min_t(unsigned, pages, layout->max_io_length / PAGE_SIZE);

  	return pages;
  }

  struct page_collect {
  	struct exofs_sb_info *sbi;

  	struct inode *inode;
  	unsigned expected_pages;

  	struct ore_io_state *ios;

  	struct page **pages;
  	unsigned alloc_pages;

  	unsigned nr_pages;
  	unsigned long length;
  	loff_t pg_first; /* keep 64bit also in 32-arches */

  	bool read_4_write; /* This means two things: that the read is sync
  			    * And the pages should not be unlocked.
  			    */

  	struct page *that_locked_page;

  };
  
  static void _pcol_init(struct page_collect *pcol, unsigned expected_pages,

  		       struct inode *inode)

  {
  	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;

  
  	pcol->sbi = sbi;

  	pcol->inode = inode;
  	pcol->expected_pages = expected_pages;

  	pcol->ios = NULL;

  	pcol->pages = NULL;
  	pcol->alloc_pages = 0;

  	pcol->nr_pages = 0;
  	pcol->length = 0;
  	pcol->pg_first = -1;

  	pcol->read_4_write = false;

  	pcol->that_locked_page = NULL;

  }
  
  static void _pcol_reset(struct page_collect *pcol)
  {
  	pcol->expected_pages -= min(pcol->nr_pages, pcol->expected_pages);

  	pcol->pages = NULL;
  	pcol->alloc_pages = 0;

  	pcol->nr_pages = 0;
  	pcol->length = 0;
  	pcol->pg_first = -1;

  	pcol->ios = NULL;

  	pcol->that_locked_page = NULL;

  
  	/* this is probably the end of the loop but in writes
  	 * it might not end here. don't be left with nothing
  	 */
  	if (!pcol->expected_pages)

  		pcol->expected_pages = MAX_PAGES_KMALLOC;

  }
  
  static int pcol_try_alloc(struct page_collect *pcol)
  {

  	unsigned pages;

  	/* TODO: easily support bio chaining */

  	pages =  exofs_max_io_pages(&pcol->sbi->layout, pcol->expected_pages);

  	for (; pages; pages >>= 1) {

  		pcol->pages = kmalloc(pages * sizeof(struct page *),
  				      GFP_KERNEL);
  		if (likely(pcol->pages)) {
  			pcol->alloc_pages = pages;

  			return 0;

  		}

  	}

  	EXOFS_ERR("Failed to kmalloc expected_pages=%u
  ",

  		  pcol->expected_pages);
  	return -ENOMEM;
  }
  
  static void pcol_free(struct page_collect *pcol)
  {

  	kfree(pcol->pages);
  	pcol->pages = NULL;

  
  	if (pcol->ios) {

  		ore_put_io_state(pcol->ios);

  		pcol->ios = NULL;
  	}

  }
  
  static int pcol_add_page(struct page_collect *pcol, struct page *page,
  			 unsigned len)
  {

  	if (unlikely(pcol->nr_pages >= pcol->alloc_pages))

  		return -ENOMEM;

  	pcol->pages[pcol->nr_pages++] = page;

  	pcol->length += len;
  	return 0;
  }

  enum {PAGE_WAS_NOT_IN_IO = 17};

  static int update_read_page(struct page *page, int ret)
  {

  	switch (ret) {
  	case 0:

  		/* Everything is OK */
  		SetPageUptodate(page);
  		if (PageError(page))
  			ClearPageError(page);

  		break;
  	case -EFAULT:

  		/* In this case we were trying to read something that wasn't on
  		 * disk yet - return a page full of zeroes.  This should be OK,
  		 * because the object should be empty (if there was a write
  		 * before this read, the read would be waiting with the page
  		 * locked */
  		clear_highpage(page);
  
  		SetPageUptodate(page);
  		if (PageError(page))
  			ClearPageError(page);

  		EXOFS_DBGMSG("recovered read error
  ");

  		/* fall through */
  	case PAGE_WAS_NOT_IN_IO:
  		ret = 0; /* recovered error */
  		break;
  	default:

  		SetPageError(page);

  	}

  	return ret;
  }
  
  static void update_write_page(struct page *page, int ret)
  {

  	if (unlikely(ret == PAGE_WAS_NOT_IN_IO))
  		return; /* don't pass start don't collect $200 */

  	if (ret) {
  		mapping_set_error(page->mapping, ret);
  		SetPageError(page);
  	}
  	end_page_writeback(page);
  }
  
  /* Called at the end of reads, to optionally unlock pages and update their
   * status.
   */

  static int __readpages_done(struct page_collect *pcol)

  {

  	int i;

  	u64 good_bytes;
  	u64 length = 0;

  	int ret = ore_check_io(pcol->ios, NULL);

  	if (likely(!ret)) {

  		good_bytes = pcol->length;

  		ret = PAGE_WAS_NOT_IN_IO;
  	} else {

  		good_bytes = 0;

  	}

  	EXOFS_DBGMSG2("readpages_done(0x%lx) good_bytes=0x%llx"

  		     " length=0x%lx nr_pages=%u
  ",
  		     pcol->inode->i_ino, _LLU(good_bytes), pcol->length,
  		     pcol->nr_pages);

  	for (i = 0; i < pcol->nr_pages; i++) {
  		struct page *page = pcol->pages[i];

  		struct inode *inode = page->mapping->host;
  		int page_stat;
  
  		if (inode != pcol->inode)
  			continue; /* osd might add more pages at end */
  
  		if (likely(length < good_bytes))
  			page_stat = 0;
  		else
  			page_stat = ret;

  		EXOFS_DBGMSG2("    readpages_done(0x%lx, 0x%lx) %s
  ",

  			  inode->i_ino, page->index,
  			  page_stat ? "bad_bytes" : "good_bytes");
  
  		ret = update_read_page(page, page_stat);

  		if (!pcol->read_4_write)

  			unlock_page(page);

  		length += PAGE_SIZE;

  	}
  
  	pcol_free(pcol);

  	EXOFS_DBGMSG2("readpages_done END
  ");

  	return ret;
  }
  
  /* callback of async reads */

  static void readpages_done(struct ore_io_state *ios, void *p)

  {
  	struct page_collect *pcol = p;

  	__readpages_done(pcol);

  	atomic_dec(&pcol->sbi->s_curr_pending);

  	kfree(pcol);

  }
  
  static void _unlock_pcol_pages(struct page_collect *pcol, int ret, int rw)
  {

  	int i;

  	for (i = 0; i < pcol->nr_pages; i++) {
  		struct page *page = pcol->pages[i];

  
  		if (rw == READ)
  			update_read_page(page, ret);
  		else
  			update_write_page(page, ret);
  
  		unlock_page(page);
  	}

  }

  static int _maybe_not_all_in_one_io(struct ore_io_state *ios,
  	struct page_collect *pcol_src, struct page_collect *pcol)
  {
  	/* length was wrong or offset was not page aligned */
  	BUG_ON(pcol_src->nr_pages < ios->nr_pages);
  
  	if (pcol_src->nr_pages > ios->nr_pages) {
  		struct page **src_page;
  		unsigned pages_less = pcol_src->nr_pages - ios->nr_pages;
  		unsigned long len_less = pcol_src->length - ios->length;
  		unsigned i;
  		int ret;
  
  		/* This IO was trimmed */
  		pcol_src->nr_pages = ios->nr_pages;
  		pcol_src->length = ios->length;
  
  		/* Left over pages are passed to the next io */
  		pcol->expected_pages += pages_less;
  		pcol->nr_pages = pages_less;
  		pcol->length = len_less;
  		src_page = pcol_src->pages + pcol_src->nr_pages;
  		pcol->pg_first = (*src_page)->index;
  
  		ret = pcol_try_alloc(pcol);
  		if (unlikely(ret))
  			return ret;
  
  		for (i = 0; i < pages_less; ++i)
  			pcol->pages[i] = *src_page++;
  
  		EXOFS_DBGMSG("Length was adjusted nr_pages=0x%x "
  			"pages_less=0x%x expected_pages=0x%x "
  			"next_offset=0x%llx next_len=0x%lx
  ",
  			pcol_src->nr_pages, pages_less, pcol->expected_pages,
  			pcol->pg_first * PAGE_SIZE, pcol->length);
  	}
  	return 0;
  }

  static int read_exec(struct page_collect *pcol)

  {
  	struct exofs_i_info *oi = exofs_i(pcol->inode);

  	struct ore_io_state *ios;

  	struct page_collect *pcol_copy = NULL;

  	int ret;

  	if (!pcol->pages)

  		return 0;

  	if (!pcol->ios) {

  		int ret = ore_get_rw_state(&pcol->sbi->layout, &oi->oc, true,

  					     pcol->pg_first << PAGE_CACHE_SHIFT,
  					     pcol->length, &pcol->ios);
  
  		if (ret)
  			return ret;
  	}
  
  	ios = pcol->ios;

  	ios->pages = pcol->pages;

  	if (pcol->read_4_write) {

  		ore_read(pcol->ios);

  		return __readpages_done(pcol);

  	}
  
  	pcol_copy = kmalloc(sizeof(*pcol_copy), GFP_KERNEL);
  	if (!pcol_copy) {
  		ret = -ENOMEM;
  		goto err;
  	}
  
  	*pcol_copy = *pcol;

  	ios->done = readpages_done;
  	ios->private = pcol_copy;

  
  	/* pages ownership was passed to pcol_copy */
  	_pcol_reset(pcol);
  
  	ret = _maybe_not_all_in_one_io(ios, pcol_copy, pcol);
  	if (unlikely(ret))
  		goto err;
  
  	EXOFS_DBGMSG2("read_exec(0x%lx) offset=0x%llx length=0x%llx
  ",
  		pcol->inode->i_ino, _LLU(ios->offset), _LLU(ios->length));

  	ret = ore_read(ios);

  	if (unlikely(ret))
  		goto err;
  
  	atomic_inc(&pcol->sbi->s_curr_pending);

  	return 0;
  
  err:

  	if (!pcol->read_4_write)

  		_unlock_pcol_pages(pcol, ret, READ);

  
  	pcol_free(pcol);

  	kfree(pcol_copy);

  	return ret;
  }
  
  /* readpage_strip is called either directly from readpage() or by the VFS from
   * within read_cache_pages(), to add one more page to be read. It will try to
   * collect as many contiguous pages as posible. If a discontinuity is
   * encountered, or it runs out of resources, it will submit the previous segment
   * and will start a new collection. Eventually caller must submit the last
   * segment if present.
   */
  static int readpage_strip(void *data, struct page *page)
  {
  	struct page_collect *pcol = data;
  	struct inode *inode = pcol->inode;
  	struct exofs_i_info *oi = exofs_i(inode);
  	loff_t i_size = i_size_read(inode);
  	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
  	size_t len;
  	int ret;
  
  	/* FIXME: Just for debugging, will be removed */
  	if (PageUptodate(page))
  		EXOFS_ERR("PageUptodate(0x%lx, 0x%lx)
  ", pcol->inode->i_ino,
  			  page->index);

  	pcol->that_locked_page = page;

  	if (page->index < end_index)
  		len = PAGE_CACHE_SIZE;
  	else if (page->index == end_index)
  		len = i_size & ~PAGE_CACHE_MASK;
  	else
  		len = 0;
  
  	if (!len || !obj_created(oi)) {
  		/* this will be out of bounds, or doesn't exist yet.
  		 * Current page is cleared and the request is split
  		 */
  		clear_highpage(page);
  
  		SetPageUptodate(page);
  		if (PageError(page))
  			ClearPageError(page);

  		if (!pcol->read_4_write)
  			unlock_page(page);

  		EXOFS_DBGMSG("readpage_strip(0x%lx) empty page len=%zx "
  			     "read_4_write=%d index=0x%lx end_index=0x%lx "
  			     "splitting
  ", inode->i_ino, len,
  			     pcol->read_4_write, page->index, end_index);

  		return read_exec(pcol);

  	}
  
  try_again:
  
  	if (unlikely(pcol->pg_first == -1)) {
  		pcol->pg_first = page->index;
  	} else if (unlikely((pcol->pg_first + pcol->nr_pages) !=
  		   page->index)) {
  		/* Discontinuity detected, split the request */

  		ret = read_exec(pcol);

  		if (unlikely(ret))
  			goto fail;
  		goto try_again;
  	}

  	if (!pcol->pages) {

  		ret = pcol_try_alloc(pcol);
  		if (unlikely(ret))
  			goto fail;
  	}
  
  	if (len != PAGE_CACHE_SIZE)
  		zero_user(page, len, PAGE_CACHE_SIZE - len);

  	EXOFS_DBGMSG2("    readpage_strip(0x%lx, 0x%lx) len=0x%zx
  ",

  		     inode->i_ino, page->index, len);
  
  	ret = pcol_add_page(pcol, page, len);
  	if (ret) {

  		EXOFS_DBGMSG2("Failed pcol_add_page pages[i]=%p "

  			  "this_len=0x%zx nr_pages=%u length=0x%lx
  ",
  			  page, len, pcol->nr_pages, pcol->length);
  
  		/* split the request, and start again with current page */

  		ret = read_exec(pcol);

  		if (unlikely(ret))
  			goto fail;
  
  		goto try_again;
  	}
  
  	return 0;
  
  fail:
  	/* SetPageError(page); ??? */
  	unlock_page(page);
  	return ret;
  }
  
  static int exofs_readpages(struct file *file, struct address_space *mapping,
  			   struct list_head *pages, unsigned nr_pages)
  {
  	struct page_collect pcol;
  	int ret;
  
  	_pcol_init(&pcol, nr_pages, mapping->host);
  
  	ret = read_cache_pages(mapping, pages, readpage_strip, &pcol);
  	if (ret) {
  		EXOFS_ERR("read_cache_pages => %d
  ", ret);
  		return ret;
  	}

  	ret = read_exec(&pcol);
  	if (unlikely(ret))
  		return ret;

  	return read_exec(&pcol);

  }

  static int _readpage(struct page *page, bool read_4_write)

  {
  	struct page_collect pcol;
  	int ret;
  
  	_pcol_init(&pcol, 1, page->mapping->host);

  	pcol.read_4_write = read_4_write;

  	ret = readpage_strip(&pcol, page);
  	if (ret) {
  		EXOFS_ERR("_readpage => %d
  ", ret);
  		return ret;
  	}

  	return read_exec(&pcol);

  }
  
  /*
   * We don't need the file
   */
  static int exofs_readpage(struct file *file, struct page *page)
  {
  	return _readpage(page, false);
  }

  /* Callback for osd_write. All writes are asynchronous */

  static void writepages_done(struct ore_io_state *ios, void *p)

  {
  	struct page_collect *pcol = p;

  	int i;

  	u64  good_bytes;
  	u64  length = 0;

  	int ret = ore_check_io(ios, NULL);

  	atomic_dec(&pcol->sbi->s_curr_pending);

  	if (likely(!ret)) {

  		good_bytes = pcol->length;

  		ret = PAGE_WAS_NOT_IN_IO;
  	} else {

  		good_bytes = 0;

  	}

  	EXOFS_DBGMSG2("writepages_done(0x%lx) good_bytes=0x%llx"

  		     " length=0x%lx nr_pages=%u
  ",
  		     pcol->inode->i_ino, _LLU(good_bytes), pcol->length,
  		     pcol->nr_pages);

  	for (i = 0; i < pcol->nr_pages; i++) {
  		struct page *page = pcol->pages[i];

  		struct inode *inode = page->mapping->host;
  		int page_stat;
  
  		if (inode != pcol->inode)
  			continue; /* osd might add more pages to a bio */
  
  		if (likely(length < good_bytes))
  			page_stat = 0;
  		else
  			page_stat = ret;
  
  		update_write_page(page, page_stat);
  		unlock_page(page);

  		EXOFS_DBGMSG2("    writepages_done(0x%lx, 0x%lx) status=%d
  ",

  			     inode->i_ino, page->index, page_stat);

  		length += PAGE_SIZE;

  	}
  
  	pcol_free(pcol);
  	kfree(pcol);

  	EXOFS_DBGMSG2("writepages_done END
  ");

  }

  static struct page *__r4w_get_page(void *priv, u64 offset, bool *uptodate)
  {
  	struct page_collect *pcol = priv;
  	pgoff_t index = offset / PAGE_SIZE;
  
  	if (!pcol->that_locked_page ||
  	    (pcol->that_locked_page->index != index)) {
  		struct page *page = find_get_page(pcol->inode->i_mapping, index);
  
  		if (!page) {
  			page = find_or_create_page(pcol->inode->i_mapping,
  						   index, GFP_NOFS);
  			if (unlikely(!page)) {
  				EXOFS_DBGMSG("grab_cache_page Failed "
  					"index=0x%llx
  ", _LLU(index));
  				return NULL;
  			}
  			unlock_page(page);
  		}
  		if (PageDirty(page) || PageWriteback(page))
  			*uptodate = true;
  		else
  			*uptodate = PageUptodate(page);
  		EXOFS_DBGMSG("index=0x%lx uptodate=%d
  ", index, *uptodate);
  		return page;
  	} else {
  		EXOFS_DBGMSG("YES that_locked_page index=0x%lx
  ",
  			     pcol->that_locked_page->index);
  		*uptodate = true;
  		return pcol->that_locked_page;
  	}
  }
  
  static void __r4w_put_page(void *priv, struct page *page)
  {
  	struct page_collect *pcol = priv;
  
  	if (pcol->that_locked_page != page) {
  		EXOFS_DBGMSG("index=0x%lx
  ", page->index);
  		page_cache_release(page);
  		return;
  	}
  	EXOFS_DBGMSG("that_locked_page index=0x%lx
  ", page->index);
  }
  
  static const struct _ore_r4w_op _r4w_op = {
  	.get_page = &__r4w_get_page,
  	.put_page = &__r4w_put_page,
  };

  static int write_exec(struct page_collect *pcol)
  {
  	struct exofs_i_info *oi = exofs_i(pcol->inode);

  	struct ore_io_state *ios;

  	struct page_collect *pcol_copy = NULL;

  	int ret;

  	if (!pcol->pages)

  		return 0;

  	BUG_ON(pcol->ios);

  	ret = ore_get_rw_state(&pcol->sbi->layout, &oi->oc, false,

  				 pcol->pg_first << PAGE_CACHE_SHIFT,
  				 pcol->length, &pcol->ios);

  	if (unlikely(ret))
  		goto err;

  	pcol_copy = kmalloc(sizeof(*pcol_copy), GFP_KERNEL);
  	if (!pcol_copy) {

  		EXOFS_ERR("write_exec: Failed to kmalloc(pcol)
  ");

  		ret = -ENOMEM;
  		goto err;
  	}
  
  	*pcol_copy = *pcol;

  	ios = pcol->ios;

  	ios->pages = pcol_copy->pages;

  	ios->done = writepages_done;

  	ios->r4w = &_r4w_op;

  	ios->private = pcol_copy;

  	/* pages ownership was passed to pcol_copy */
  	_pcol_reset(pcol);
  
  	ret = _maybe_not_all_in_one_io(ios, pcol_copy, pcol);
  	if (unlikely(ret))
  		goto err;
  
  	EXOFS_DBGMSG2("write_exec(0x%lx) offset=0x%llx length=0x%llx
  ",
  		pcol->inode->i_ino, _LLU(ios->offset), _LLU(ios->length));

  	ret = ore_write(ios);

  	if (unlikely(ret)) {

  		EXOFS_ERR("write_exec: ore_write() Failed
  ");

  		goto err;
  	}
  
  	atomic_inc(&pcol->sbi->s_curr_pending);

  	return 0;
  
  err:
  	_unlock_pcol_pages(pcol, ret, WRITE);

  	pcol_free(pcol);

  	kfree(pcol_copy);

  	return ret;
  }
  
  /* writepage_strip is called either directly from writepage() or by the VFS from
   * within write_cache_pages(), to add one more page to be written to storage.
   * It will try to collect as many contiguous pages as possible. If a
   * discontinuity is encountered or it runs out of resources it will submit the
   * previous segment and will start a new collection.
   * Eventually caller must submit the last segment if present.
   */
  static int writepage_strip(struct page *page,
  			   struct writeback_control *wbc_unused, void *data)
  {
  	struct page_collect *pcol = data;
  	struct inode *inode = pcol->inode;
  	struct exofs_i_info *oi = exofs_i(inode);
  	loff_t i_size = i_size_read(inode);
  	pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
  	size_t len;
  	int ret;
  
  	BUG_ON(!PageLocked(page));
  
  	ret = wait_obj_created(oi);
  	if (unlikely(ret))
  		goto fail;
  
  	if (page->index < end_index)
  		/* in this case, the page is within the limits of the file */
  		len = PAGE_CACHE_SIZE;
  	else {
  		len = i_size & ~PAGE_CACHE_MASK;
  
  		if (page->index > end_index || !len) {
  			/* in this case, the page is outside the limits
  			 * (truncate in progress)
  			 */
  			ret = write_exec(pcol);
  			if (unlikely(ret))
  				goto fail;
  			if (PageError(page))
  				ClearPageError(page);
  			unlock_page(page);

  			EXOFS_DBGMSG("writepage_strip(0x%lx, 0x%lx) "
  				     "outside the limits
  ",
  				     inode->i_ino, page->index);

  			return 0;
  		}
  	}
  
  try_again:
  
  	if (unlikely(pcol->pg_first == -1)) {
  		pcol->pg_first = page->index;
  	} else if (unlikely((pcol->pg_first + pcol->nr_pages) !=
  		   page->index)) {
  		/* Discontinuity detected, split the request */
  		ret = write_exec(pcol);
  		if (unlikely(ret))
  			goto fail;

  
  		EXOFS_DBGMSG("writepage_strip(0x%lx, 0x%lx) Discontinuity
  ",
  			     inode->i_ino, page->index);

  		goto try_again;
  	}

  	if (!pcol->pages) {

  		ret = pcol_try_alloc(pcol);
  		if (unlikely(ret))
  			goto fail;
  	}

  	EXOFS_DBGMSG2("    writepage_strip(0x%lx, 0x%lx) len=0x%zx
  ",

  		     inode->i_ino, page->index, len);
  
  	ret = pcol_add_page(pcol, page, len);
  	if (unlikely(ret)) {

  		EXOFS_DBGMSG2("Failed pcol_add_page "

  			     "nr_pages=%u total_length=0x%lx
  ",
  			     pcol->nr_pages, pcol->length);
  
  		/* split the request, next loop will start again */
  		ret = write_exec(pcol);
  		if (unlikely(ret)) {

  			EXOFS_DBGMSG("write_exec failed => %d", ret);

  			goto fail;
  		}
  
  		goto try_again;
  	}
  
  	BUG_ON(PageWriteback(page));
  	set_page_writeback(page);
  
  	return 0;
  
  fail:

  	EXOFS_DBGMSG("Error: writepage_strip(0x%lx, 0x%lx)=>%d
  ",
  		     inode->i_ino, page->index, ret);

  	set_bit(AS_EIO, &page->mapping->flags);
  	unlock_page(page);
  	return ret;
  }
  
  static int exofs_writepages(struct address_space *mapping,
  		       struct writeback_control *wbc)
  {
  	struct page_collect pcol;
  	long start, end, expected_pages;
  	int ret;
  
  	start = wbc->range_start >> PAGE_CACHE_SHIFT;
  	end = (wbc->range_end == LLONG_MAX) ?
  			start + mapping->nrpages :
  			wbc->range_end >> PAGE_CACHE_SHIFT;
  
  	if (start || end)

  		expected_pages = end - start + 1;

  	else
  		expected_pages = mapping->nrpages;

  	if (expected_pages < 32L)
  		expected_pages = 32L;

  	EXOFS_DBGMSG2("inode(0x%lx) wbc->start=0x%llx wbc->end=0x%llx "

  		     "nrpages=%lu start=0x%lx end=0x%lx expected_pages=%ld
  ",

  		     mapping->host->i_ino, wbc->range_start, wbc->range_end,

  		     mapping->nrpages, start, end, expected_pages);

  
  	_pcol_init(&pcol, expected_pages, mapping->host);
  
  	ret = write_cache_pages(mapping, wbc, writepage_strip, &pcol);

  	if (unlikely(ret)) {

  		EXOFS_ERR("write_cache_pages => %d
  ", ret);
  		return ret;
  	}

  	ret = write_exec(&pcol);
  	if (unlikely(ret))
  		return ret;
  
  	if (wbc->sync_mode == WB_SYNC_ALL) {
  		return write_exec(&pcol); /* pump the last reminder */
  	} else if (pcol.nr_pages) {
  		/* not SYNC let the reminder join the next writeout */
  		unsigned i;
  
  		for (i = 0; i < pcol.nr_pages; i++) {
  			struct page *page = pcol.pages[i];
  
  			end_page_writeback(page);
  			set_page_dirty(page);
  			unlock_page(page);
  		}
  	}
  	return 0;

  }

  /*

  static int exofs_writepage(struct page *page, struct writeback_control *wbc)
  {
  	struct page_collect pcol;
  	int ret;
  
  	_pcol_init(&pcol, 1, page->mapping->host);
  
  	ret = writepage_strip(page, NULL, &pcol);
  	if (ret) {
  		EXOFS_ERR("exofs_writepage => %d
  ", ret);
  		return ret;
  	}
  
  	return write_exec(&pcol);
  }

  */

  /* i_mutex held using inode->i_size directly */
  static void _write_failed(struct inode *inode, loff_t to)
  {
  	if (to > inode->i_size)
  		truncate_pagecache(inode, to, inode->i_size);
  }

  int exofs_write_begin(struct file *file, struct address_space *mapping,
  		loff_t pos, unsigned len, unsigned flags,
  		struct page **pagep, void **fsdata)
  {
  	int ret = 0;
  	struct page *page;
  
  	page = *pagep;
  	if (page == NULL) {
  		ret = simple_write_begin(file, mapping, pos, len, flags, pagep,
  					 fsdata);
  		if (ret) {

  			EXOFS_DBGMSG("simple_write_begin failed
  ");

  			goto out;

  		}
  
  		page = *pagep;
  	}
  
  	 /* read modify write */
  	if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {

  		loff_t i_size = i_size_read(mapping->host);
  		pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
  		size_t rlen;
  
  		if (page->index < end_index)
  			rlen = PAGE_CACHE_SIZE;
  		else if (page->index == end_index)
  			rlen = i_size & ~PAGE_CACHE_MASK;
  		else
  			rlen = 0;
  
  		if (!rlen) {
  			clear_highpage(page);
  			SetPageUptodate(page);
  			goto out;
  		}

  		ret = _readpage(page, true);
  		if (ret) {
  			/*SetPageError was done by _readpage. Is it ok?*/
  			unlock_page(page);

  			EXOFS_DBGMSG("__readpage failed
  ");

  		}
  	}

  out:
  	if (unlikely(ret))
  		_write_failed(mapping->host, pos + len);

  
  	return ret;
  }
  
  static int exofs_write_begin_export(struct file *file,
  		struct address_space *mapping,
  		loff_t pos, unsigned len, unsigned flags,
  		struct page **pagep, void **fsdata)
  {
  	*pagep = NULL;
  
  	return exofs_write_begin(file, mapping, pos, len, flags, pagep,
  					fsdata);
  }

  static int exofs_write_end(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned copied,
  			struct page *page, void *fsdata)
  {
  	struct inode *inode = mapping->host;
  	/* According to comment in simple_write_end i_mutex is held */
  	loff_t i_size = inode->i_size;
  	int ret;
  
  	ret = simple_write_end(file, mapping,pos, len, copied, page, fsdata);

  	if (unlikely(ret))
  		_write_failed(inode, pos + len);
  
  	/* TODO: once simple_write_end marks inode dirty remove */

  	if (i_size != inode->i_size)
  		mark_inode_dirty(inode);
  	return ret;
  }

  static int exofs_releasepage(struct page *page, gfp_t gfp)
  {
  	EXOFS_DBGMSG("page 0x%lx
  ", page->index);
  	WARN_ON(1);

  	return 0;

  }
  
  static void exofs_invalidatepage(struct page *page, unsigned long offset)
  {

  	EXOFS_DBGMSG("page 0x%lx offset 0x%lx
  ", page->index, offset);

  	WARN_ON(1);

  }

  const struct address_space_operations exofs_aops = {
  	.readpage	= exofs_readpage,
  	.readpages	= exofs_readpages,

  	.writepage	= NULL,

  	.writepages	= exofs_writepages,
  	.write_begin	= exofs_write_begin_export,

  	.write_end	= exofs_write_end,

  	.releasepage	= exofs_releasepage,
  	.set_page_dirty	= __set_page_dirty_nobuffers,
  	.invalidatepage = exofs_invalidatepage,
  
  	/* Not implemented Yet */
  	.bmap		= NULL, /* TODO: use osd's OSD_ACT_READ_MAP */
  	.direct_IO	= NULL, /* TODO: Should be trivial to do */
  
  	/* With these NULL has special meaning or default is not exported */

  	.get_xip_mem	= NULL,
  	.migratepage	= NULL,
  	.launder_page	= NULL,
  	.is_partially_uptodate = NULL,
  	.error_remove_page = NULL,

  };

  /******************************************************************************
   * INODE OPERATIONS
   *****************************************************************************/
  
  /*
   * Test whether an inode is a fast symlink.
   */
  static inline int exofs_inode_is_fast_symlink(struct inode *inode)
  {
  	struct exofs_i_info *oi = exofs_i(inode);
  
  	return S_ISLNK(inode->i_mode) && (oi->i_data[0] != 0);
  }

  static int _do_truncate(struct inode *inode, loff_t newsize)

  {
  	struct exofs_i_info *oi = exofs_i(inode);

  	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;

  	int ret;
  
  	inode->i_mtime = inode->i_ctime = CURRENT_TIME;

  	ret = ore_truncate(&sbi->layout, &oi->oc, (u64)newsize);

  	if (likely(!ret))
  		truncate_setsize(inode, newsize);

  	EXOFS_DBGMSG("(0x%lx) size=0x%llx ret=>%d
  ",
  		     inode->i_ino, newsize, ret);

  	return ret;
  }

  /*

   * Set inode attributes - update size attribute on OSD if needed,
   *                        otherwise just call generic functions.

   */
  int exofs_setattr(struct dentry *dentry, struct iattr *iattr)
  {
  	struct inode *inode = dentry->d_inode;
  	int error;

  	/* if we are about to modify an object, and it hasn't been
  	 * created yet, wait
  	 */
  	error = wait_obj_created(exofs_i(inode));
  	if (unlikely(error))
  		return error;

  	error = inode_change_ok(inode, iattr);

  	if (unlikely(error))

  		return error;

  	if ((iattr->ia_valid & ATTR_SIZE) &&
  	    iattr->ia_size != i_size_read(inode)) {

  		error = _do_truncate(inode, iattr->ia_size);
  		if (unlikely(error))

  			return error;
  	}
  
  	setattr_copy(inode, iattr);
  	mark_inode_dirty(inode);
  	return 0;

  }

  static const struct osd_attr g_attr_inode_file_layout = ATTR_DEF(
  	EXOFS_APAGE_FS_DATA,
  	EXOFS_ATTR_INODE_FILE_LAYOUT,
  	0);
  static const struct osd_attr g_attr_inode_dir_layout = ATTR_DEF(
  	EXOFS_APAGE_FS_DATA,
  	EXOFS_ATTR_INODE_DIR_LAYOUT,
  	0);

  /*

   * Read the Linux inode info from the OSD, and return it as is. In exofs the
   * inode info is in an application specific page/attribute of the osd-object.

   */
  static int exofs_get_inode(struct super_block *sb, struct exofs_i_info *oi,

  		    struct exofs_fcb *inode)

  {
  	struct exofs_sb_info *sbi = sb->s_fs_info;

  	struct osd_attr attrs[] = {
  		[0] = g_attr_inode_data,
  		[1] = g_attr_inode_file_layout,
  		[2] = g_attr_inode_dir_layout,

  	};

  	struct ore_io_state *ios;

  	struct exofs_on_disk_inode_layout *layout;

  	int ret;

  	ret = ore_get_io_state(&sbi->layout, &oi->oc, &ios);

  	if (unlikely(ret)) {

  		EXOFS_ERR("%s: ore_get_io_state failed.
  ", __func__);

  		return ret;

  	}

  	attrs[1].len = exofs_on_disk_inode_layout_size(sbi->oc.numdevs);
  	attrs[2].len = exofs_on_disk_inode_layout_size(sbi->oc.numdevs);

  	ios->in_attr = attrs;
  	ios->in_attr_len = ARRAY_SIZE(attrs);

  	ret = ore_read(ios);

  	if (unlikely(ret)) {
  		EXOFS_ERR("object(0x%llx) corrupted, return empty file=>%d
  ",

  			  _LLU(oi->one_comp.obj.id), ret);

  		memset(inode, 0, sizeof(*inode));
  		inode->i_mode = 0040000 | (0777 & ~022);
  		/* If object is lost on target we might as well enable it's
  		 * delete.
  		 */
  		if ((ret == -ENOENT) || (ret == -EINVAL))
  			ret = 0;

  		goto out;

  	}

  	ret = extract_attr_from_ios(ios, &attrs[0]);

  	if (ret) {

  		EXOFS_ERR("%s: extract_attr of inode_data failed
  ", __func__);

  		goto out;
  	}

  	WARN_ON(attrs[0].len != EXOFS_INO_ATTR_SIZE);
  	memcpy(inode, attrs[0].val_ptr, EXOFS_INO_ATTR_SIZE);

  	ret = extract_attr_from_ios(ios, &attrs[1]);

  	if (ret) {

  		EXOFS_ERR("%s: extract_attr of inode_data failed
  ", __func__);
  		goto out;
  	}
  	if (attrs[1].len) {
  		layout = attrs[1].val_ptr;
  		if (layout->gen_func != cpu_to_le16(LAYOUT_MOVING_WINDOW)) {
  			EXOFS_ERR("%s: unsupported files layout %d
  ",
  				__func__, layout->gen_func);
  			ret = -ENOTSUPP;
  			goto out;
  		}
  	}
  
  	ret = extract_attr_from_ios(ios, &attrs[2]);
  	if (ret) {
  		EXOFS_ERR("%s: extract_attr of inode_data failed
  ", __func__);
  		goto out;
  	}
  	if (attrs[2].len) {
  		layout = attrs[2].val_ptr;
  		if (layout->gen_func != cpu_to_le16(LAYOUT_MOVING_WINDOW)) {
  			EXOFS_ERR("%s: unsupported meta-data layout %d
  ",
  				__func__, layout->gen_func);
  			ret = -ENOTSUPP;
  			goto out;
  		}
  	}

  out:

  	ore_put_io_state(ios);

  	return ret;
  }

  static void __oi_init(struct exofs_i_info *oi)
  {
  	init_waitqueue_head(&oi->i_wq);
  	oi->i_flags = 0;
  }

  /*
   * Fill in an inode read from the OSD and set it up for use
   */
  struct inode *exofs_iget(struct super_block *sb, unsigned long ino)
  {
  	struct exofs_i_info *oi;
  	struct exofs_fcb fcb;
  	struct inode *inode;

  	int ret;
  
  	inode = iget_locked(sb, ino);
  	if (!inode)
  		return ERR_PTR(-ENOMEM);
  	if (!(inode->i_state & I_NEW))
  		return inode;
  	oi = exofs_i(inode);

  	__oi_init(oi);

  	exofs_init_comps(&oi->oc, &oi->one_comp, sb->s_fs_info,

  			 exofs_oi_objno(oi));

  
  	/* read the inode from the osd */

  	ret = exofs_get_inode(sb, oi, &fcb);

  	if (ret)
  		goto bad_inode;

  	set_obj_created(oi);
  
  	/* copy stuff from on-disk struct to in-memory struct */
  	inode->i_mode = le16_to_cpu(fcb.i_mode);
  	inode->i_uid = le32_to_cpu(fcb.i_uid);
  	inode->i_gid = le32_to_cpu(fcb.i_gid);

  	set_nlink(inode, le16_to_cpu(fcb.i_links_count));

  	inode->i_ctime.tv_sec = (signed)le32_to_cpu(fcb.i_ctime);
  	inode->i_atime.tv_sec = (signed)le32_to_cpu(fcb.i_atime);
  	inode->i_mtime.tv_sec = (signed)le32_to_cpu(fcb.i_mtime);
  	inode->i_ctime.tv_nsec =
  		inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = 0;
  	oi->i_commit_size = le64_to_cpu(fcb.i_size);
  	i_size_write(inode, oi->i_commit_size);
  	inode->i_blkbits = EXOFS_BLKSHIFT;
  	inode->i_generation = le32_to_cpu(fcb.i_generation);

  	oi->i_dir_start_lookup = 0;
  
  	if ((inode->i_nlink == 0) && (inode->i_mode == 0)) {
  		ret = -ESTALE;
  		goto bad_inode;
  	}
  
  	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
  		if (fcb.i_data[0])
  			inode->i_rdev =
  				old_decode_dev(le32_to_cpu(fcb.i_data[0]));
  		else
  			inode->i_rdev =
  				new_decode_dev(le32_to_cpu(fcb.i_data[1]));
  	} else {
  		memcpy(oi->i_data, fcb.i_data, sizeof(fcb.i_data));
  	}

  	inode->i_mapping->backing_dev_info = sb->s_bdi;

  	if (S_ISREG(inode->i_mode)) {
  		inode->i_op = &exofs_file_inode_operations;
  		inode->i_fop = &exofs_file_operations;
  		inode->i_mapping->a_ops = &exofs_aops;
  	} else if (S_ISDIR(inode->i_mode)) {
  		inode->i_op = &exofs_dir_inode_operations;
  		inode->i_fop = &exofs_dir_operations;
  		inode->i_mapping->a_ops = &exofs_aops;
  	} else if (S_ISLNK(inode->i_mode)) {
  		if (exofs_inode_is_fast_symlink(inode))
  			inode->i_op = &exofs_fast_symlink_inode_operations;
  		else {
  			inode->i_op = &exofs_symlink_inode_operations;
  			inode->i_mapping->a_ops = &exofs_aops;
  		}
  	} else {
  		inode->i_op = &exofs_special_inode_operations;
  		if (fcb.i_data[0])
  			init_special_inode(inode, inode->i_mode,
  			   old_decode_dev(le32_to_cpu(fcb.i_data[0])));
  		else
  			init_special_inode(inode, inode->i_mode,
  			   new_decode_dev(le32_to_cpu(fcb.i_data[1])));
  	}
  
  	unlock_new_inode(inode);
  	return inode;
  
  bad_inode:
  	iget_failed(inode);
  	return ERR_PTR(ret);
  }
  
  int __exofs_wait_obj_created(struct exofs_i_info *oi)
  {
  	if (!obj_created(oi)) {

  		EXOFS_DBGMSG("!obj_created
  ");

  		BUG_ON(!obj_2bcreated(oi));
  		wait_event(oi->i_wq, obj_created(oi));

  		EXOFS_DBGMSG("wait_event done
  ");

  	}
  	return unlikely(is_bad_inode(&oi->vfs_inode)) ? -EIO : 0;
  }

  /*
   * Callback function from exofs_new_inode().  The important thing is that we
   * set the obj_created flag so that other methods know that the object exists on
   * the OSD.
   */

  static void create_done(struct ore_io_state *ios, void *p)

  {
  	struct inode *inode = p;
  	struct exofs_i_info *oi = exofs_i(inode);
  	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
  	int ret;

  	ret = ore_check_io(ios, NULL);
  	ore_put_io_state(ios);

  	atomic_dec(&sbi->s_curr_pending);
  
  	if (unlikely(ret)) {

  		EXOFS_ERR("object=0x%llx creation failed in pid=0x%llx",

  			  _LLU(exofs_oi_objno(oi)),
  			  _LLU(oi->one_comp.obj.partition));

  		/*TODO: When FS is corrupted creation can fail, object already
  		 * exist. Get rid of this asynchronous creation, if exist
  		 * increment the obj counter and try the next object. Until we
  		 * succeed. All these dangling objects will be made into lost
  		 * files by chkfs.exofs
  		 */
  	}
  
  	set_obj_created(oi);

  	wake_up(&oi->i_wq);
  }
  
  /*
   * Set up a new inode and create an object for it on the OSD
   */

  struct inode *exofs_new_inode(struct inode *dir, umode_t mode)

  {

  	struct super_block *sb = dir->i_sb;
  	struct exofs_sb_info *sbi = sb->s_fs_info;

  	struct inode *inode;
  	struct exofs_i_info *oi;

  	struct ore_io_state *ios;

  	int ret;

  	inode = new_inode(sb);
  	if (!inode)
  		return ERR_PTR(-ENOMEM);
  
  	oi = exofs_i(inode);

  	__oi_init(oi);

  	set_obj_2bcreated(oi);

  	inode->i_mapping->backing_dev_info = sb->s_bdi;

  	inode_init_owner(inode, dir, mode);

  	inode->i_ino = sbi->s_nextid++;
  	inode->i_blkbits = EXOFS_BLKSHIFT;
  	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  	oi->i_commit_size = inode->i_size = 0;
  	spin_lock(&sbi->s_next_gen_lock);
  	inode->i_generation = sbi->s_next_generation++;
  	spin_unlock(&sbi->s_next_gen_lock);
  	insert_inode_hash(inode);

  	exofs_init_comps(&oi->oc, &oi->one_comp, sb->s_fs_info,

  			 exofs_oi_objno(oi));

  	exofs_sbi_write_stats(sbi); /* Make sure new sbi->s_nextid is on disk */

  	mark_inode_dirty(inode);

  	ret = ore_get_io_state(&sbi->layout, &oi->oc, &ios);

  	if (unlikely(ret)) {

  		EXOFS_ERR("exofs_new_inode: ore_get_io_state failed
  ");

  		return ERR_PTR(ret);

  	}

  	ios->done = create_done;
  	ios->private = inode;

  	ret = ore_create(ios);

  	if (ret) {

  		ore_put_io_state(ios);

  		return ERR_PTR(ret);

  	}
  	atomic_inc(&sbi->s_curr_pending);
  
  	return inode;
  }

  
  /*
   * struct to pass two arguments to update_inode's callback
   */
  struct updatei_args {
  	struct exofs_sb_info	*sbi;
  	struct exofs_fcb	fcb;
  };
  
  /*
   * Callback function from exofs_update_inode().
   */

  static void updatei_done(struct ore_io_state *ios, void *p)

  {
  	struct updatei_args *args = p;

  	ore_put_io_state(ios);

  
  	atomic_dec(&args->sbi->s_curr_pending);
  
  	kfree(args);
  }
  
  /*
   * Write the inode to the OSD.  Just fill up the struct, and set the attribute
   * synchronously or asynchronously depending on the do_sync flag.
   */
  static int exofs_update_inode(struct inode *inode, int do_sync)
  {
  	struct exofs_i_info *oi = exofs_i(inode);
  	struct super_block *sb = inode->i_sb;
  	struct exofs_sb_info *sbi = sb->s_fs_info;

  	struct ore_io_state *ios;

  	struct osd_attr attr;
  	struct exofs_fcb *fcb;
  	struct updatei_args *args;
  	int ret;
  
  	args = kzalloc(sizeof(*args), GFP_KERNEL);

  	if (!args) {

  		EXOFS_DBGMSG("Failed kzalloc of args
  ");

  		return -ENOMEM;

  	}

  
  	fcb = &args->fcb;
  
  	fcb->i_mode = cpu_to_le16(inode->i_mode);
  	fcb->i_uid = cpu_to_le32(inode->i_uid);
  	fcb->i_gid = cpu_to_le32(inode->i_gid);
  	fcb->i_links_count = cpu_to_le16(inode->i_nlink);
  	fcb->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
  	fcb->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
  	fcb->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
  	oi->i_commit_size = i_size_read(inode);
  	fcb->i_size = cpu_to_le64(oi->i_commit_size);
  	fcb->i_generation = cpu_to_le32(inode->i_generation);
  
  	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
  		if (old_valid_dev(inode->i_rdev)) {
  			fcb->i_data[0] =
  				cpu_to_le32(old_encode_dev(inode->i_rdev));
  			fcb->i_data[1] = 0;
  		} else {
  			fcb->i_data[0] = 0;
  			fcb->i_data[1] =
  				cpu_to_le32(new_encode_dev(inode->i_rdev));
  			fcb->i_data[2] = 0;
  		}
  	} else
  		memcpy(fcb->i_data, oi->i_data, sizeof(fcb->i_data));

  	ret = ore_get_io_state(&sbi->layout, &oi->oc, &ios);

  	if (unlikely(ret)) {

  		EXOFS_ERR("%s: ore_get_io_state failed.
  ", __func__);

  		goto free_args;
  	}

  	attr = g_attr_inode_data;
  	attr.val_ptr = fcb;

  	ios->out_attr_len = 1;
  	ios->out_attr = &attr;

  	wait_obj_created(oi);

  	if (!do_sync) {

  		args->sbi = sbi;

  		ios->done = updatei_done;
  		ios->private = args;
  	}

  	ret = ore_write(ios);

  	if (!do_sync && !ret) {

  		atomic_inc(&sbi->s_curr_pending);
  		goto out; /* deallocation in updatei_done */
  	}

  	ore_put_io_state(ios);

  free_args:
  	kfree(args);
  out:

  	EXOFS_DBGMSG("(0x%lx) do_sync=%d ret=>%d
  ",
  		     inode->i_ino, do_sync, ret);

  	return ret;
  }

  int exofs_write_inode(struct inode *inode, struct writeback_control *wbc)

  {

  	/* FIXME: fix fsync and use wbc->sync_mode == WB_SYNC_ALL */
  	return exofs_update_inode(inode, 1);

  }
  
  /*
   * Callback function from exofs_delete_inode() - don't have much cleaning up to
   * do.
   */

  static void delete_done(struct ore_io_state *ios, void *p)

  {

  	struct exofs_sb_info *sbi = p;

  	ore_put_io_state(ios);

  	atomic_dec(&sbi->s_curr_pending);
  }
  
  /*
   * Called when the refcount of an inode reaches zero.  We remove the object
   * from the OSD here.  We make sure the object was created before we try and
   * delete it.
   */

  void exofs_evict_inode(struct inode *inode)

  {
  	struct exofs_i_info *oi = exofs_i(inode);
  	struct super_block *sb = inode->i_sb;
  	struct exofs_sb_info *sbi = sb->s_fs_info;

  	struct ore_io_state *ios;

  	int ret;
  
  	truncate_inode_pages(&inode->i_data, 0);

  	/* TODO: should do better here */

  	if (inode->i_nlink || is_bad_inode(inode))

  		goto no_delete;

  	inode->i_size = 0;

  	end_writeback(inode);

  	/* if we are deleting an obj that hasn't been created yet, wait.
  	 * This also makes sure that create_done cannot be called with an
  	 * already evicted inode.
  	 */
  	wait_obj_created(oi);
  	/* ignore the error, attempt a remove anyway */

  
  	/* Now Remove the OSD objects */

  	ret = ore_get_io_state(&sbi->layout, &oi->oc, &ios);

  	if (unlikely(ret)) {

  		EXOFS_ERR("%s: ore_get_io_state failed
  ", __func__);

  		return;

  	}

  	ios->done = delete_done;
  	ios->private = sbi;

  	ret = ore_remove(ios);

  	if (ret) {

  		EXOFS_ERR("%s: ore_remove failed
  ", __func__);
  		ore_put_io_state(ios);

  		return;
  	}
  	atomic_inc(&sbi->s_curr_pending);
  
  	return;
  
  no_delete:

  	end_writeback(inode);

  }