Btrfs: Cleanup and comment ordered-data.c

		unlock_extent(io_tree, page_start, page_end, GFP_NOFS);

		unlock_page(page);

		page_cache_release(page);

		btrfs_wait_ordered_extent(inode, ordered);

		btrfs_start_ordered_extent(inode, ordered, 1);

		btrfs_put_ordered_extent(ordered);

		goto again;

	}

	ordered = btrfs_lookup_ordered_extent(page->mapping->host,

					   page_offset(page));

	if (ordered) {

		/*

		 * IO on this page will never be started, so we need

		 * to account for any ordered extents now

		 */

		clear_extent_bit(tree, page_start, page_end,

				 EXTENT_DIRTY | EXTENT_DELALLOC |

				 EXTENT_LOCKED, 1, 0, GFP_NOFS);

	lock_extent(io_tree, page_start, page_end, GFP_NOFS);

	set_page_extent_mapped(page);

	/*

	 * we can't set the delalloc bits if there are pending ordered

	 * extents.  Drop our locks and wait for them to finish

	 */

	ordered = btrfs_lookup_ordered_extent(inode, page_start);

	if (ordered) {

		unlock_extent(io_tree, page_start, page_end, GFP_NOFS);

		unlock_page(page);

		btrfs_wait_ordered_extent(inode, ordered);

		btrfs_start_ordered_extent(inode, ordered, 1);

		btrfs_put_ordered_extent(ordered);

		goto again;

	}

	return ret;

}

/* allocate and add a new ordered_extent into the per-inode tree.

 * file_offset is the logical offset in the file

 *

 * start is the disk block number of an extent already reserved in the

 * extent allocation tree

 *

 * len is the length of the extent

 *

 * This also sets the EXTENT_ORDERED bit on the range in the inode.

 *

 * The tree is given a single reference on the ordered extent that was

 * inserted.

 */

int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,

			     u64 start, u64 len)

{

	entry->file_offset = file_offset;

	entry->start = start;

	entry->len = len;

	entry->inode = inode;

	/* one ref for the tree */

	atomic_set(&entry->refs, 1);

	init_waitqueue_head(&entry->wait);

	set_extent_ordered(&BTRFS_I(inode)->io_tree, file_offset,

			   entry_end(entry) - 1, GFP_NOFS);

	set_bit(BTRFS_ORDERED_START, &entry->flags);

	mutex_unlock(&tree->mutex);

	BUG_ON(node);

	return 0;

}

/*

 * Add a struct btrfs_ordered_sum into the list of checksums to be inserted

 * when an ordered extent is finished.

 */

int btrfs_add_ordered_sum(struct inode *inode, struct btrfs_ordered_sum *sum)

{

	struct btrfs_ordered_inode_tree *tree;

	tree = &BTRFS_I(inode)->ordered_tree;

	mutex_lock(&tree->mutex);

	node = tree_search(tree, sum->file_offset);

	if (!node) {

search_fail:

printk("add ordered sum failed to find a node for inode %lu offset %Lu\n", inode->i_ino, sum->file_offset);

		node = rb_first(&tree->tree);

		while(node) {

			entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);

			printk("entry %Lu %Lu %Lu\n", entry->file_offset, entry->file_offset + entry->len, entry->start);

			node = rb_next(node);

		}

		BUG();

	}

	BUG_ON(!node);

	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);

	if (!offset_in_entry(entry, sum->file_offset)) {

		goto search_fail;

	}

	BUG_ON(!offset_in_entry(entry, sum->file_offset));

	list_add_tail(&sum->list, &entry->list);

	mutex_unlock(&tree->mutex);

	return 0;

}

/*

 * this is used to account for finished IO across a given range

 * of the file.  The IO should not span ordered extents.  If

 * a given ordered_extent is completely done, 1 is returned, otherwise

 * 0.

 *

 * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used

 * to make sure this function only returns 1 once for a given ordered extent.

 */

int btrfs_dec_test_ordered_pending(struct inode *inode,

				   u64 file_offset, u64 io_size)

{

	ret = test_range_bit(io_tree, entry->file_offset,

			     entry->file_offset + entry->len - 1,

			     EXTENT_ORDERED, 0);

	if (!test_bit(BTRFS_ORDERED_START, &entry->flags)) {

printk("inode %lu not ready yet for extent %Lu %Lu\n", inode->i_ino, entry->file_offset, entry_end(entry));

	}

	if (ret == 0)

		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);

out:

	return ret == 0;

}

/*

 * used to drop a reference on an ordered extent.  This will free

 * the extent if the last reference is dropped

 */

int btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)

{

	struct list_head *cur;

	return 0;

}

/*

 * remove an ordered extent from the tree.  No references are dropped

 * but, anyone waiting on this extent is woken up.

 */

int btrfs_remove_ordered_extent(struct inode *inode,

				struct btrfs_ordered_extent *entry)

{

	return 0;

}

void btrfs_wait_ordered_extent(struct inode *inode,

			       struct btrfs_ordered_extent *entry)

{

	u64 start = entry->file_offset;

	u64 end = start + entry->len - 1;

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)

	do_sync_file_range(file, start, end, SYNC_FILE_RANGE_WRITE);

#else

	do_sync_mapping_range(inode->i_mapping, start, end,

			      SYNC_FILE_RANGE_WRITE);

#endif

	wait_event(entry->wait,

		   test_bit(BTRFS_ORDERED_COMPLETE, &entry->flags));

}

static void btrfs_start_ordered_extent(struct inode *inode,

			       struct btrfs_ordered_extent *entry, int wait)

/*

 * Used to start IO or wait for a given ordered extent to finish.

 *

 * If wait is one, this effectively waits on page writeback for all the pages

 * in the extent, and it waits on the io completion code to insert

 * metadata into the btree corresponding to the extent

 */

void btrfs_start_ordered_extent(struct inode *inode,

				       struct btrfs_ordered_extent *entry,

				       int wait)

{

	u64 start = entry->file_offset;

	u64 end = start + entry->len - 1;

	/*

	 * pages in the range can be dirty, clean or writeback.  We

	 * start IO on any dirty ones so the wait doesn't stall waiting

	 * for pdflush to find them

	 */

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22)

	do_sync_file_range(file, start, end, SYNC_FILE_RANGE_WRITE);

#else

						 &entry->flags));

}

/*

 * Used to wait on ordered extents across a large range of bytes.

 */

void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)

{

	u64 end;

	}

}

int btrfs_add_ordered_pending(struct inode *inode,

			      struct btrfs_ordered_extent *ordered,

			      u64 start, u64 len)

{

	WARN_ON(1);

	return 0;

#if 0

	int ret;

	struct btrfs_ordered_inode_tree *tree;

	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;

	tree = &BTRFS_I(inode)->ordered_tree;

	mutex_lock(&tree->mutex);

	if (test_bit(BTRFS_ORDERED_IO_DONE, &ordered->flags)) {

		ret = -EAGAIN;

		goto out;

	}

	set_extent_ordered(io_tree, start, start + len - 1, GFP_NOFS);

	ret = 0;

out:

	mutex_unlock(&tree->mutex);

	return ret;

#endif

}

/*

 * find an ordered extent corresponding to file_offset.  return NULL if

 * nothing is found, otherwise take a reference on the extent and return it

 */

struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,

							 u64 file_offset)

{

	return entry;

}

/*

 * lookup and return any extent before 'file_offset'.  NULL is returned

 * if none is found

 */

struct btrfs_ordered_extent *

btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset)

{

	return entry;

}

/*

 * After an extent is done, call this to conditionally update the on disk

 * i_size.  i_size is updated to cover any fully written part of the file.

 */

int btrfs_ordered_update_i_size(struct inode *inode,

				struct btrfs_ordered_extent *ordered)

{

	return 0;

}

/*

 * search the ordered extents for one corresponding to 'offset' and

 * try to find a checksum.  This is used because we allow pages to

 * be reclaimed before their checksum is actually put into the btree

 */

int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u32 *sum)

{

	struct btrfs_ordered_sum *ordered_sum;

#ifndef __BTRFS_ORDERED_DATA__

#define __BTRFS_ORDERED_DATA__

/* one of these per inode */

struct btrfs_ordered_inode_tree {

	struct mutex mutex;

	struct rb_root tree;

	struct rb_node *last;

};

/*

 * these are used to collect checksums done just before bios submission.

 * They are attached via a list into the ordered extent, and

 * checksum items are inserted into the tree after all the blocks in

 * the ordered extent are on disk

 */

struct btrfs_sector_sum {

	u64 offset;

	u32 sum;

	u64 file_offset;

	u64 len;

	struct list_head list;

	/* last field is a variable length array of btrfs_sector_sums */

	struct btrfs_sector_sum sums;

};

/* bits for the flags field */

/*

 * bits for the flags field:

 *

 * BTRFS_ORDERED_IO_DONE is set when all of the blocks are written.

 * It is used to make sure metadata is inserted into the tree only once

 * per extent.

 *

 * BTRFS_ORDERED_COMPLETE is set when the extent is removed from the

 * rbtree, just before waking any waiters.  It is used to indicate the

 * IO is done and any metadata is inserted into the tree.

 */

#define BTRFS_ORDERED_IO_DONE 0 /* set when all the pages are written */

#define BTRFS_ORDERED_COMPLETE 1 /* set when removed from the tree */

#define BTRFS_ORDERED_START 2 /* set when tree setup */

struct btrfs_ordered_extent {

	/* logical offset in the file */

	u64 file_offset;

	/* disk byte number */

	u64 start;

	/* length of the extent in bytes */

	u64 len;

	/* flags (described above) */

	unsigned long flags;

	/* reference count */

	atomic_t refs;

	/* list of checksums for insertion when the extent io is done */

	struct list_head list;

	struct inode *inode;

	/* used to wait for the BTRFS_ORDERED_COMPLETE bit */

	wait_queue_head_t wait;

	/* our friendly rbtree entry */

	struct rb_node rb_node;

};

/*

 * calculates the total size you need to allocate for an ordered sum

 * structure spanning 'bytes' in the file

 */

static inline int btrfs_ordered_sum_size(struct btrfs_root *root, u64 bytes)

{

	unsigned long num_sectors = (bytes + root->sectorsize - 1) /

int btrfs_add_ordered_sum(struct inode *inode, struct btrfs_ordered_sum *sum);

struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,

							 u64 file_offset);

void btrfs_wait_ordered_extent(struct inode *inode,

			       struct btrfs_ordered_extent *entry);

void btrfs_start_ordered_extent(struct inode *inode,

				struct btrfs_ordered_extent *entry, int wait);

void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len);

struct btrfs_ordered_extent *

btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset);

int btrfs_add_ordered_pending(struct inode *inode,

			      struct btrfs_ordered_extent *ordered,

			      u64 start, u64 len);

int btrfs_ordered_update_i_size(struct inode *inode,

				struct btrfs_ordered_extent *ordered);

int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u32 *sum);