litmus-rt.git - The LITMUS^RT kernel.

/*
 * Copyright (C) 2007 Oracle.  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/slab.h>
#include <linux/blkdev.h>
#include <linux/writeback.h>
#include <linux/pagevec.h>
#include "ctree.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "extent_io.h"
#include "disk-io.h"

static struct kmem_cache *btrfs_ordered_extent_cache;

static u64 entry_end(struct btrfs_ordered_extent *entry)
{
	if (entry->file_offset + entry->len < entry->file_offset)
		return (u64)-1;
	return entry->file_offset + entry->len;
}

/* returns NULL if the insertion worked, or it returns the node it did find
 * in the tree
 */
static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset,
				   struct rb_node *node)
{
	struct rb_node **p = &root->rb_node;
	struct rb_node *parent = NULL;
	struct btrfs_ordered_extent *entry;

	while (*p) {
		parent = *p;
		entry = rb_entry(parent, struct btrfs_ordered_extent, rb_node);

		if (file_offset < entry->file_offset)
			p = &(*p)->rb_left;
		else if (file_offset >= entry_end(entry))
			p = &(*p)->rb_right;
		else
			return parent;
	}

	rb_link_node(node, parent, p);
	rb_insert_color(node, root);
	return NULL;
}

static void ordered_data_tree_panic(struct inode *inode, int errno,
					       u64 offset)
{
	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
	btrfs_panic(fs_info, errno, "Inconsistency in ordered tree at offset "
		    "%llu\n", offset);
}

/*
 * look for a given offset in the tree, and if it can't be found return the
 * first lesser offset
 */
static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
				     struct rb_node **prev_ret)
{
	struct rb_node *n = root->rb_node;
	struct rb_node *prev = NULL;
	struct rb_node *test;
	struct btrfs_ordered_extent *entry;
	struct btrfs_ordered_extent *prev_entry = NULL;

	while (n) {
		entry = rb_entry(n, struct btrfs_ordered_extent, rb_node);
		prev = n;
		prev_entry = entry;

		if (file_offset < entry->file_offset)
			n = n->rb_left;
		else if (file_offset >= entry_end(entry))
			n = n->rb_right;
		else
			return n;
	}
	if (!prev_ret)
		return NULL;

	while (prev && file_offset >= entry_end(prev_entry)) {
		test = rb_next(prev);
		if (!test)
			break;
		prev_entry = rb_entry(test, struct btrfs_ordered_extent,
				      rb_node);
		if (file_offset < entry_end(prev_entry))
			break;

		prev = test;
	}
	if (prev)
		prev_entry = rb_entry(prev, struct btrfs_ordered_extent,
				      rb_node);
	while (prev && file_offset < entry_end(prev_entry)) {
		test = rb_prev(prev);
		if (!test)
			break;
		prev_entry = rb_entry(test, struct btrfs_ordered_extent,
				      rb_node);
		prev = test;
	}
	*prev_ret = prev;
	return NULL;
}

/*
 * helper to check if a given offset is inside a given entry
 */
static int offset_in_entry(struct btrfs_ordered_extent *entry, u64 file_offset)
{
	if (file_offset < entry->file_offset ||
	    entry->file_offset + entry->len <= file_offset)
		return 0;
	return 1;
}

static int range_overlaps(struct btrfs_ordered_extent *entry, u64 file_offset,
			  u64 len)
{
	if (file_offset + len <= entry->file_offset ||
	    entry->file_offset + entry->len <= file_offset)
		return 0;
	return 1;
}

/*
 * look find the first ordered struct that has this offset, otherwise
 * the first one less than this offset
 */
static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
					  u64 file_offset)
{
	struct rb_root *root = &tree->tree;
	struct rb_node *prev = NULL;
	struct rb_node *ret;
	struct btrfs_ordered_extent *entry;

	if (tree->last) {
		entry = rb_entry(tree->last, struct btrfs_ordered_extent,
				 rb_node);
		if (offset_in_entry(entry, file_offset))
			return tree->last;
	}
	ret = __tree_search(root, file_offset, &prev);
	if (!ret)
		ret = prev;
	if (ret)
		tree->last = ret;
	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
 *
 * The tree is given a single reference on the ordered extent that was
 * inserted.
 */
static int __btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
				      u64 start, u64 len, u64 disk_len,
				      int type, int dio, int compress_type)
{
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_ordered_inode_tree *tree;
	struct rb_node *node;
	struct btrfs_ordered_extent *entry;

	tree = &BTRFS_I(inode)->ordered_tree;
	entry = kmem_cache_zalloc(btrfs_ordered_extent_cache, GFP_NOFS);
	if (!entry)
		return -ENOMEM;

	entry->file_offset = file_offset;
	entry->start = start;
	entry->len = len;
	if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) &&
	    !(type == BTRFS_ORDERED_NOCOW))
		entry->csum_bytes_left = disk_len;
	entry->disk_len = disk_len;
	entry->bytes_left = len;
	entry->inode = igrab(inode);
	entry->compress_type = compress_type;
	entry->truncated_len = (u64)-1;
	if (type != BTRFS_ORDERED_IO_DONE && type != BTRFS_ORDERED_COMPLETE)
		set_bit(type, &entry->flags);

	if (dio)
		set_bit(BTRFS_ORDERED_DIRECT, &entry->flags);

	/* one ref for the tree */
	atomic_set(&entry->refs, 1);
	init_waitqueue_head(&entry->wait);
	INIT_LIST_HEAD(&entry->list);
	INIT_LIST_HEAD(&entry->root_extent_list);
	INIT_LIST_HEAD(&entry->work_list);
	init_completion(&entry->completion);
	INIT_LIST_HEAD(&entry->log_list);

	trace_btrfs_ordered_extent_add(inode, entry);

	spin_lock_irq(&tree->lock);
	node = tree_insert(&tree->tree, file_offset,
			   &entry->rb_node);
	if (node)
		ordered_data_tree_panic(inode, -EEXIST, file_offset);
	spin_unlock_irq(&tree->lock);

	spin_lock(&root->ordered_extent_lock);
	list_add_tail(&entry->root_extent_list,
		      &root->ordered_extents);
	root->nr_ordered_extents++;
	if (root->nr_ordered_extents == 1) {
		spin_lock(&root->fs_info->ordered_root_lock);
		BUG_ON(!list_empty(&root->ordered_root));
		list_add_tail(&root->ordered_root,
			      &root->fs_info->ordered_roots);
		spin_unlock(&root->fs_info->ordered_root_lock);
	}
	spin_unlock(&root->ordered_extent_lock);

	return 0;
}

int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
			     u64 start, u64 len, u64 disk_len, int type)
{
	return __btrfs_add_ordered_extent(inode, file_offset, start, len,
					  disk_len, type, 0,
					  BTRFS_COMPRESS_NONE);
}

int btrfs_add_ordered_extent_dio(struct inode *inode, u64 file_offset,
				 u64 start, u64 len, u64 disk_len, int type)
{
	return __btrfs_add_ordered_extent(inode, file_offset, start, len,
					  disk_len, type, 1,
					  BTRFS_COMPRESS_NONE);
}

int btrfs_add_ordered_extent_compress(struct inode *inode, u64 file_offset,
				      u64 start, u64 len, u64 disk_len,
				      int type, int compress_type)
{
	return __btrfs_add_ordered_extent(inode, file_offset, start, len,
					  disk_len, type, 0,
					  compress_type);
}

/*
 * Add a struct btrfs_ordered_sum into the list of checksums to be inserted
 * when an ordered extent is finished.  If the list covers more than one
 * ordered extent, it is split across multiples.
 */
void btrfs_add_ordered_sum(struct inode *inode,
			   struct btrfs_ordered_extent *entry,
			   struct btrfs_ordered_sum *sum)
{
	struct btrfs_ordered_inode_tree *tree;

	tree = &BTRFS_I(inode)->ordered_tree;
	spin_lock_irq(&tree->lock);
	list_add_tail(&sum->list, &entry->list);
	WARN_ON(entry->csum_bytes_left < sum->len);
	entry->csum_bytes_left -= sum->len;
	if (entry->csum_bytes_left == 0)
		wake_up(&entry->wait);
	spin_unlock_irq(&tree->lock);
}

/*
 * this is used to account for finished IO across a given range
 * of the file.  The IO may 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.
 *
 * file_offset is updated to one byte past the range that is recorded as
 * complete.  This allows you to walk forward in the file.
 */
int btrfs_dec_test_first_ordered_pending(struct inode *inode,
				   struct btrfs_ordered_extent **cached,
				   u64 *file_offset, u64 io_size, int uptodate)
{
	struct btrfs_ordered_inode_tree *tree;
	struct rb_node *node;
	struct btrfs_ordered_extent *entry = NULL;
	int ret;
	unsigned long flags;
	u64 dec_end;
	u64 dec_start;
	u64 to_dec;

	tree = &BTRFS_I(inode)->ordered_tree;
	spin_lock_irqsave(&tree->lock, flags);
	node = tree_search(tree, *file_offset);
	if (!node) {
		ret = 1;
		goto out;
	}

	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
	if (!offset_in_entry(entry, *file_offset)) {
		ret = 1;
		goto out;
	}

	dec_start = max(*file_offset, entry->file_offset);
	dec_end = min(*file_offset + io_size, entry->file_offset +
		      entry->len);
	*file_offset = dec_end;
	if (dec_start > dec_end) {
		printk(KERN_CRIT "bad ordering dec_start %llu end %llu\n",
		       dec_start, dec_end);
	}
	to_dec = dec_end - dec_start;
	if (to_dec > entry->bytes_left) {
		printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
		       entry->bytes_left, to_dec);
	}
	entry->bytes_left -= to_dec;
	if (!uptodate)
		set_bit(BTRFS_ORDERED_IOERR, &entry->flags);

	if (entry->bytes_left == 0)
		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
	else
		ret = 1;
out:
	if (!ret && cached && entry) {
		*cached = entry;
		atomic_inc(&entry->refs);
	}
	spin_unlock_irqrestore(&tree->lock, flags);
	return ret == 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,
				   struct btrfs_ordered_extent **cached,
				   u64 file_offset, u64 io_size, int uptodate)
{
	struct btrfs_ordered_inode_tree *tree;
	struct rb_node *node;
	struct btrfs_ordered_extent *entry = NULL;
	unsigned long flags;
	int ret;

	tree = &BTRFS_I(inode)->ordered_tree;
	spin_lock_irqsave(&tree->lock, flags);
	if (cached && *cached) {
		entry = *cached;
		goto have_entry;
	}

	node = tree_search(tree, file_offset);
	if (!node) {
		ret = 1;
		goto out;
	}

	entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
have_entry:
	if (!offset_in_entry(entry, file_offset)) {
		ret = 1;
		goto out;
	}

	if (io_size > entry->bytes_left) {
		printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
		       entry->bytes_left, io_size);
	}
	entry->bytes_left -= io_size;
	if (!uptodate)
		set_bit(BTRFS_ORDERED_IOERR, &entry->flags);

	if (entry->bytes_left == 0)
		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
	else
		ret = 1;
out:
	if (!ret && cached && entry) {
		*cached = entry;
		atomic_inc(&entry->refs);
	}
	spin_unlock_irqrestore(&tree->lock, flags);
	return ret == 0;
}

/* Needs to either be called under a log transaction or the log_mutex */
void btrfs_get_logged_extents(struct btrfs_root *log, struct inode *inode)
{
	struct btrfs_ordered_inode_tree *tree;
	struct btrfs_ordered_extent *ordered;
	struct rb_node *n;
	int index = log->log_transid % 2;

	tree = &BTRFS_I(inode)->ordered_tree;
	spin_lock_irq(&tree->lock);
	for (n = rb_first(&tree->tree); n; n = rb_next(n)) {
		ordered = rb_entry(n, struct btrfs_ordered_extent, rb_node);
		spin_lock(&log->log_extents_lock[index]);
		if (list_empty(&ordered->log_list)) {
			list_add_tail(&ordered->log_list, &log->logged_list[index]);
			atomic_inc(&ordered->refs);
		}
		spin_unlock(&log->log_extents_lock[index]);
	}
	spin_unlock_irq(&tree->lock);
}

void btrfs_wait_logged_extents(struct btrfs_root *log, u64 transid)
{
	struct btrfs_ordered_extent *ordered;
	int index = transid % 2;

	spin_lock_irq(&log->log_extents_lock[index]);
	while (!list_empty(&log->logged_list[index])) {
		ordered = list_first_entry(&log->logged_list[index],
					   struct btrfs_ordered_extent,
					   log_list);
		list_del_init(&ordered->log_list);
		spin_unlock_irq(&log->log_extents_lock[index]);
		wait_event(ordered->wait, test_bit(BTRFS_ORDERED_IO_DONE,
						   &ordered->flags));
		btrfs_put_ordered_extent(ordered);
		spin_lock_irq(&log->log_extents_lock[index]);
	}
	spin_unlock_irq(&log->log_extents_lock[index]);
}

void btrfs_free_logged_extents(struct btrfs_root *log, u64 transid)
{
	struct btrfs_ordered_extent *ordered;
	int index = transid % 2;

	spin_lock_irq(&log->log_extents_lock[index]);
	while (!list_empty(&log->logged_list[index])) {
		ordered = list_first_entry(&log->logged_list[index],
					   struct btrfs_ordered_extent,
					   log_list);
		list_del_init(&ordered->log_list);
		spin_unlock_irq(&log->log_extents_lock[index]);
		btrfs_put_ordered_extent(ordered);
		spin_lock_irq(&log->log_extents_lock[index]);
	}
	spin_unlock_irq(&log->log_extents_lock[index]);
}

/*
 * used to drop a reference on an ordered extent.  This will free
 * the extent if the last reference is dropped
 */
void btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
{
	struct list_head *cur;
	struct btrfs_ordered_sum *sum;

	trace_btrfs_ordered_extent_put(entry->inode, entry);

	if (atomic_dec_and_test(&entry->refs)) {
		if (entry->inode)
			btrfs_add_delayed_iput(entry->inode);
		while (!list_empty(&entry->list)) {
			cur = entry->list.next;
			sum = list_entry(cur, struct btrfs_ordered_sum, list);
			list_del(&sum->list);
			kfree(sum);
		}
		kmem_cache_free(btrfs_ordered_extent_cache, entry);
	}
}

/*
 * remove an ordered extent from the tree.  No references are dropped
 * and waiters are woken up.
 */
void btrfs_remove_ordered_extent(struct inode *inode,
				 struct btrfs_ordered_extent *entry)
{
	struct btrfs_ordered_inode_tree *tree;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct rb_node *node;

	tree = &BTRFS_I(inode)->ordered_tree;
	spin_lock_irq(&tree->lock);
	node = &entry->rb_node;
	rb_erase(node, &tree->tree);
	tree->last = NULL;
	set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);
	spin_unlock_irq(&tree->lock);

	spin_lock(&root->ordered_extent_lock);
	list_del_init(&entry->root_extent_list);
	root->nr_ordered_extents--;

	trace_btrfs_ordered_extent_remove(inode, entry);

	/*
	 * we have no more ordered extents for this inode and
	 * no dirty pages.  We can safely remove it from the
	 * list of ordered extents
	 */
	if (RB_EMPTY_ROOT(&tree->tree) &&
	    !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) {
		list_del_init(&BTRFS_I(inode)->ordered_operations);
	}

	if (!root->nr_ordered_extents) {
		spin_lock(&root->fs_info->ordered_root_lock);
		BUG_ON(list_empty(&root->ordered_root));
		list_del_init(&root->ordered_root);
		spin_unlock(&root->fs_info->ordered_root_lock);
	}
	spin_unlock(&root->ordered_extent_lock);
	wake_up(&entry->wait);
}

static void btrfs_run_ordered_extent_work(struct btrfs_work *work)
{
	struct btrfs_ordered_extent *ordered;

	ordered = container_of(work, struct btrfs_ordered_extent, flush_work);
	btrfs_start_ordered_extent(ordered->inode, ordered, 1);
	complete(&ordered->completion);
}

/*
 * wait for all the ordered extents in a root.  This is done when balancing
 * space between drives.
 */
void btrfs_wait_ordered_extents(struct btrfs_root *root, int delay_iput)
{
	struct list_head splice, works;
	struct btrfs_ordered_extent *ordered, *next;
	struct inode *inode;

	INIT_LIST_HEAD(&splice);
	INIT_LIST_HEAD(&works);

	mutex_lock(&root->fs_info->ordered_operations_mutex);
	spin_lock(&root->ordered_extent_lock);
	list_splice_init(&root->ordered_extents, &splice);
	while (!list_empty(&splice)) {
		ordered = list_first_entry(&splice, struct btrfs_ordered_extent,
					   root_extent_list);
		list_move_tail(&ordered->root_extent_list,
			       &root->ordered_extents);
		/*
		 * the inode may be getting freed (in sys_unlink path).
		 */
		inode = igrab(ordered->inode);
		if (!inode) {


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