/*
   * Copyright (C) 2013 Fusion IO.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License v2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/pagemap.h>
  #include <linux/sched.h>
  #include "btrfs-tests.h"
  #include "../extent_io.h"
  
  #define PROCESS_UNLOCK		(1 << 0)
  #define PROCESS_RELEASE		(1 << 1)
  #define PROCESS_TEST_LOCKED	(1 << 2)
  
  static noinline int process_page_range(struct inode *inode, u64 start, u64 end,
  				       unsigned long flags)
  {
  	int ret;
  	struct page *pages[16];
  	unsigned long index = start >> PAGE_CACHE_SHIFT;
  	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
  	unsigned long nr_pages = end_index - index + 1;
  	int i;
  	int count = 0;
  	int loops = 0;
  
  	while (nr_pages > 0) {
  		ret = find_get_pages_contig(inode->i_mapping, index,
  				     min_t(unsigned long, nr_pages,
  				     ARRAY_SIZE(pages)), pages);
  		for (i = 0; i < ret; i++) {
  			if (flags & PROCESS_TEST_LOCKED &&
  			    !PageLocked(pages[i]))
  				count++;
  			if (flags & PROCESS_UNLOCK && PageLocked(pages[i]))
  				unlock_page(pages[i]);
  			page_cache_release(pages[i]);
  			if (flags & PROCESS_RELEASE)
  				page_cache_release(pages[i]);
  		}
  		nr_pages -= ret;
  		index += ret;
  		cond_resched();
  		loops++;
  		if (loops > 100000) {
  			printk(KERN_ERR "stuck in a loop, start %Lu, end %Lu, nr_pages %lu, ret %d
  ", start, end, nr_pages, ret);
  			break;
  		}
  	}
  	return count;
  }
  
  static int test_find_delalloc(void)
  {
  	struct inode *inode;
  	struct extent_io_tree tmp;
  	struct page *page;
  	struct page *locked_page = NULL;
  	unsigned long index = 0;
  	u64 total_dirty = 256 * 1024 * 1024;
  	u64 max_bytes = 128 * 1024 * 1024;
  	u64 start, end, test_start;
  	u64 found;
  	int ret = -EINVAL;
  
  	inode = btrfs_new_test_inode();
  	if (!inode) {
  		test_msg("Failed to allocate test inode
  ");
  		return -ENOMEM;
  	}
  
  	extent_io_tree_init(&tmp, &inode->i_data);
  
  	/*
  	 * First go through and create and mark all of our pages dirty, we pin
  	 * everything to make sure our pages don't get evicted and screw up our
  	 * test.
  	 */
  	for (index = 0; index < (total_dirty >> PAGE_CACHE_SHIFT); index++) {
  		page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
  		if (!page) {
  			test_msg("Failed to allocate test page
  ");
  			ret = -ENOMEM;
  			goto out;
  		}
  		SetPageDirty(page);
  		if (index) {
  			unlock_page(page);
  		} else {
  			page_cache_get(page);
  			locked_page = page;
  		}
  	}
  
  	/* Test this scenario
  	 * |--- delalloc ---|
  	 * |---  search  ---|
  	 */
  	set_extent_delalloc(&tmp, 0, 4095, NULL, GFP_NOFS);
  	start = 0;
  	end = 0;
  	found = find_lock_delalloc_range(inode, &tmp, locked_page, &start,
  					 &end, max_bytes);
  	if (!found) {
  		test_msg("Should have found at least one delalloc
  ");
  		goto out_bits;
  	}
  	if (start != 0 || end != 4095) {
  		test_msg("Expected start 0 end 4095, got start %Lu end %Lu
  ",
  			 start, end);
  		goto out_bits;
  	}
  	unlock_extent(&tmp, start, end);
  	unlock_page(locked_page);
  	page_cache_release(locked_page);
  
  	/*
  	 * Test this scenario
  	 *
  	 * |--- delalloc ---|
  	 *           |--- search ---|
  	 */
  	test_start = 64 * 1024 * 1024;
  	locked_page = find_lock_page(inode->i_mapping,
  				     test_start >> PAGE_CACHE_SHIFT);
  	if (!locked_page) {
  		test_msg("Couldn't find the locked page
  ");
  		goto out_bits;
  	}
  	set_extent_delalloc(&tmp, 4096, max_bytes - 1, NULL, GFP_NOFS);
  	start = test_start;
  	end = 0;
  	found = find_lock_delalloc_range(inode, &tmp, locked_page, &start,
  					 &end, max_bytes);
  	if (!found) {
  		test_msg("Couldn't find delalloc in our range
  ");
  		goto out_bits;
  	}
  	if (start != test_start || end != max_bytes - 1) {
  		test_msg("Expected start %Lu end %Lu, got start %Lu, end "
  			 "%Lu
  ", test_start, max_bytes - 1, start, end);
  		goto out_bits;
  	}
  	if (process_page_range(inode, start, end,
  			       PROCESS_TEST_LOCKED | PROCESS_UNLOCK)) {
  		test_msg("There were unlocked pages in the range
  ");
  		goto out_bits;
  	}
  	unlock_extent(&tmp, start, end);
  	/* locked_page was unlocked above */
  	page_cache_release(locked_page);
  
  	/*
  	 * Test this scenario
  	 * |--- delalloc ---|
  	 *                    |--- search ---|
  	 */
  	test_start = max_bytes + 4096;
  	locked_page = find_lock_page(inode->i_mapping, test_start >>
  				     PAGE_CACHE_SHIFT);
  	if (!locked_page) {
  		test_msg("Could'nt find the locked page
  ");
  		goto out_bits;
  	}
  	start = test_start;
  	end = 0;
  	found = find_lock_delalloc_range(inode, &tmp, locked_page, &start,
  					 &end, max_bytes);
  	if (found) {
  		test_msg("Found range when we shouldn't have
  ");
  		goto out_bits;
  	}
  	if (end != (u64)-1) {
  		test_msg("Did not return the proper end offset
  ");
  		goto out_bits;
  	}
  
  	/*
  	 * Test this scenario
  	 * [------- delalloc -------|
  	 * [max_bytes]|-- search--|
  	 *
  	 * We are re-using our test_start from above since it works out well.
  	 */
  	set_extent_delalloc(&tmp, max_bytes, total_dirty - 1, NULL, GFP_NOFS);
  	start = test_start;
  	end = 0;
  	found = find_lock_delalloc_range(inode, &tmp, locked_page, &start,
  					 &end, max_bytes);
  	if (!found) {
  		test_msg("Didn't find our range
  ");
  		goto out_bits;
  	}
  	if (start != test_start || end != total_dirty - 1) {
  		test_msg("Expected start %Lu end %Lu, got start %Lu end %Lu
  ",
  			 test_start, total_dirty - 1, start, end);
  		goto out_bits;
  	}
  	if (process_page_range(inode, start, end,
  			       PROCESS_TEST_LOCKED | PROCESS_UNLOCK)) {
  		test_msg("Pages in range were not all locked
  ");
  		goto out_bits;
  	}
  	unlock_extent(&tmp, start, end);
  
  	/*
  	 * Now to test where we run into a page that is no longer dirty in the
  	 * range we want to find.
  	 */
  	page = find_get_page(inode->i_mapping, (max_bytes + (1 * 1024 * 1024))
  			     >> PAGE_CACHE_SHIFT);
  	if (!page) {
  		test_msg("Couldn't find our page
  ");
  		goto out_bits;
  	}
  	ClearPageDirty(page);
  	page_cache_release(page);
  
  	/* We unlocked it in the previous test */
  	lock_page(locked_page);
  	start = test_start;
  	end = 0;
  	/*
  	 * Currently if we fail to find dirty pages in the delalloc range we
  	 * will adjust max_bytes down to PAGE_CACHE_SIZE and then re-search.  If
  	 * this changes at any point in the future we will need to fix this
  	 * tests expected behavior.
  	 */
  	found = find_lock_delalloc_range(inode, &tmp, locked_page, &start,
  					 &end, max_bytes);
  	if (!found) {
  		test_msg("Didn't find our range
  ");
  		goto out_bits;
  	}
  	if (start != test_start && end != test_start + PAGE_CACHE_SIZE - 1) {
  		test_msg("Expected start %Lu end %Lu, got start %Lu end %Lu
  ",
  			 test_start, test_start + PAGE_CACHE_SIZE - 1, start,
  			 end);
  		goto out_bits;
  	}
  	if (process_page_range(inode, start, end, PROCESS_TEST_LOCKED |
  			       PROCESS_UNLOCK)) {
  		test_msg("Pages in range were not all locked
  ");
  		goto out_bits;
  	}
  	ret = 0;
  out_bits:
  	clear_extent_bits(&tmp, 0, total_dirty - 1,
  			  (unsigned long)-1, GFP_NOFS);
  out:
  	if (locked_page)
  		page_cache_release(locked_page);
  	process_page_range(inode, 0, total_dirty - 1,
  			   PROCESS_UNLOCK | PROCESS_RELEASE);
  	iput(inode);
  	return ret;
  }
  
  int btrfs_test_extent_io(void)
  {
  	test_msg("Running find delalloc tests
  ");
  	return test_find_delalloc();
  }