Commit ed2ff2cb authored by Chris Mason's avatar Chris Mason Committed by David Woodhouse
Browse files

Btrfs: pretend page cache & commit code 



Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 79f95c82

fs/btrfs/ctree.c

+40 −26
Original line number Diff line number Diff line
@@ -250,6 +250,7 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path, 
		tree_block_release(root, mid_buf);

		/* once for the root ptr */

		tree_block_release(root, mid_buf);

		clean_tree_block(root, mid_buf);

		return free_extent(root, blocknr, 1);

	}

	parent = &parent_buf->node;
@@ -280,6 +281,7 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path, 
		if (right->header.nritems == 0) {

			u64 blocknr = right_buf->blocknr;

			tree_block_release(root, right_buf);

			clean_tree_block(root, right_buf);

			right_buf = NULL;

			right = NULL;

			wret = del_ptr(root, path, level + 1, pslot + 1);
@@ -291,7 +293,7 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path, 
		} else {

			memcpy(parent->keys + pslot + 1, right->keys,

				sizeof(struct key));

			wret = write_tree_block(root, parent_buf);

			wret = dirty_tree_block(root, parent_buf);

			if (wret)

				ret = wret;

		}
@@ -316,6 +318,7 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path, 
		/* we've managed to empty the middle node, drop it */

		u64 blocknr = mid_buf->blocknr;

		tree_block_release(root, mid_buf);

		clean_tree_block(root, mid_buf);

		mid_buf = NULL;

		mid = NULL;

		wret = del_ptr(root, path, level + 1, pslot);
@@ -327,7 +330,7 @@ static int balance_level(struct ctree_root *root, struct ctree_path *path, 
	} else {

		/* update the parent key to reflect our changes */

		memcpy(parent->keys + pslot, mid->keys, sizeof(struct key));

		wret = write_tree_block(root, parent_buf);

		wret = dirty_tree_block(root, parent_buf);

		if (wret)

			ret = wret;

	}
@@ -458,7 +461,7 @@ static int fixup_low_keys(struct ctree_root *root, 
			break;

		t = &path->nodes[i]->node;

		memcpy(t->keys + tslot, key, sizeof(*key));

		wret = write_tree_block(root, path->nodes[i]);

		wret = dirty_tree_block(root, path->nodes[i]);

		if (wret)

			ret = wret;

		if (tslot != 0)
@@ -508,11 +511,11 @@ static int push_node_left(struct ctree_root *root, struct tree_buffer *dst_buf, 
	src->header.nritems -= push_items;

	dst->header.nritems += push_items;



	wret = write_tree_block(root, src_buf);

	wret = dirty_tree_block(root, src_buf);

	if (wret < 0)

		ret = wret;



	wret = write_tree_block(root, dst_buf);

	wret = dirty_tree_block(root, dst_buf);

	if (wret < 0)

		ret = wret;

	return ret;
@@ -566,11 +569,11 @@ static int balance_node_right(struct ctree_root *root, 
	src->header.nritems -= push_items;

	dst->header.nritems += push_items;



	wret = write_tree_block(root, src_buf);

	wret = dirty_tree_block(root, src_buf);

	if (wret < 0)

		ret = wret;



	wret = write_tree_block(root, dst_buf);

	wret = dirty_tree_block(root, dst_buf);

	if (wret < 0)

		ret = wret;

	return ret;
@@ -612,7 +615,7 @@ static int insert_new_root(struct ctree_root *root, 
	tree_block_release(root, root->node);

	root->node = t;

	t->count++;

	write_tree_block(root, t);

	dirty_tree_block(root, t);

	path->nodes[level] = t;

	path->slots[level] = 0;

	return 0;
@@ -652,7 +655,7 @@ static int insert_ptr(struct ctree_root *root, 
	lower->header.nritems++;

	if (lower->keys[1].objectid == 0)

			BUG();

	write_tree_block(root, path->nodes[level]);

	dirty_tree_block(root, path->nodes[level]);

	return 0;

}
@@ -698,10 +701,10 @@ static int split_node(struct ctree_root *root, struct ctree_path *path, 
	c->header.nritems = mid;

	ret = 0;



	wret = write_tree_block(root, t);

	wret = dirty_tree_block(root, t);

	if (wret)

		ret = wret;

	wret = write_tree_block(root, split_buffer);

	wret = dirty_tree_block(root, split_buffer);

	if (wret)

		ret = wret;

	wret = insert_ptr(root, path, split->keys, split_buffer->blocknr,
@@ -815,11 +818,11 @@ static int push_leaf_right(struct ctree_root *root, struct ctree_path *path, 
	}

	left->header.nritems -= push_items;



	write_tree_block(root, left_buf);

	write_tree_block(root, right_buf);

	dirty_tree_block(root, left_buf);

	dirty_tree_block(root, right_buf);

	memcpy(upper->node.keys + slot + 1,

		&right->items[0].key, sizeof(struct key));

	write_tree_block(root, upper);

	dirty_tree_block(root, upper);

	/* then fixup the leaf pointer in the path */

	if (path->slots[0] >= left->header.nritems) {

		path->slots[0] -= left->header.nritems;
@@ -909,10 +912,10 @@ static int push_leaf_left(struct ctree_root *root, struct ctree_path *path, 
		push_space = right->items[i].offset;

	}



	wret = write_tree_block(root, t);

	wret = dirty_tree_block(root, t);

	if (wret)

		ret = wret;

	wret = write_tree_block(root, right_buf);

	wret = dirty_tree_block(root, right_buf);

	if (wret)

		ret = wret;
@@ -1019,10 +1022,10 @@ static int split_leaf(struct ctree_root *root, struct ctree_path *path, 
			  right_buffer->blocknr, path->slots[1] + 1, 1);

	if (wret)

		ret = wret;

	wret = write_tree_block(root, right_buffer);

	wret = dirty_tree_block(root, right_buffer);

	if (wret)

		ret = wret;

	wret = write_tree_block(root, l_buf);

	wret = dirty_tree_block(root, l_buf);

	if (wret)

		ret = wret;
@@ -1062,12 +1065,14 @@ int insert_item(struct ctree_root *root, struct key *key, 
	ret = search_slot(root, key, &path, data_size);

	if (ret == 0) {

		release_path(root, &path);

		return -EEXIST;

	}

	if (ret < 0) {

		release_path(root, &path);

		ret = -EEXIST;

		wret = commit_transaction(root);

		if (wret)

			ret = wret;

		return ret;

	}

	if (ret < 0)

		goto out;



	slot_orig = path.slots[0];

	leaf_buf = path.nodes[0];
@@ -1113,14 +1118,18 @@ int insert_item(struct ctree_root *root, struct key *key, 
	if (slot == 0)

		ret = fixup_low_keys(root, &path, key, 1);



	wret = write_tree_block(root, leaf_buf);

	wret = dirty_tree_block(root, leaf_buf);

	if (wret)

		ret = wret;



	if (leaf_free_space(leaf) < 0)

		BUG();

	check_leaf(&path, 0);

out:

	release_path(root, &path);

	wret = commit_transaction(root);

	if (wret)

		ret = wret;

	return ret;

}
@@ -1160,7 +1169,7 @@ static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level, 
		if (wret)

			ret = wret;

	}

	wret = write_tree_block(root, parent);

	wret = dirty_tree_block(root, parent);

	if (wret)

		ret = wret;

	return ret;
@@ -1203,8 +1212,9 @@ int del_item(struct ctree_root *root, struct ctree_path *path) 
	if (leaf->header.nritems == 0) {

		if (leaf_buf == root->node) {

			leaf->header.flags = node_level(0);

			write_tree_block(root, leaf_buf);

			dirty_tree_block(root, leaf_buf);

		} else {

			clean_tree_block(root, leaf_buf);

			wret = del_ptr(root, path, 1, path->slots[1]);

			if (wret)

				ret = wret;
@@ -1220,7 +1230,7 @@ int del_item(struct ctree_root *root, struct ctree_path *path) 
			if (wret)

				ret = wret;

		}

		wret = write_tree_block(root, leaf_buf);

		wret = dirty_tree_block(root, leaf_buf);

		if (wret)

			ret = wret;
@@ -1242,6 +1252,7 @@ int del_item(struct ctree_root *root, struct ctree_path *path) 
			}

			if (leaf->header.nritems == 0) {

				u64 blocknr = leaf_buf->blocknr;

				clean_tree_block(root, leaf_buf);

				wret = del_ptr(root, path, 1, slot);

				if (wret)

					ret = wret;
@@ -1254,6 +1265,9 @@ int del_item(struct ctree_root *root, struct ctree_path *path) 
			}

		}

	}

	wret = commit_transaction(root);

	if (wret)

		ret = wret;

	return ret;

}

fs/btrfs/ctree.h

+5 −0
Original line number Diff line number Diff line 
#ifndef __CTREE__

#define __CTREE__



#include "list.h"



#define CTREE_BLOCKSIZE 1024



/*
@@ -53,6 +55,9 @@ struct ctree_root { 
	struct key current_insert;

	int fp;

	struct radix_tree_root cache_radix;

	struct list_head trans;

	struct list_head cache;

	int cache_size;

};



/*

fs/btrfs/disk-io.c

+89 −2
Original line number Diff line number Diff line
@@ -11,6 +11,8 @@ 
#include "disk-io.h"



static int allocated_blocks = 0;

int cache_size = 0;

int cache_max = 10000;



static int check_tree_block(struct ctree_root *root, struct tree_buffer *buf)

{
@@ -21,6 +23,25 @@ static int check_tree_block(struct ctree_root *root, struct tree_buffer *buf) 
	return 0;

}



static int free_some_buffers(struct ctree_root *root)

{

	struct list_head *node, *next;

	struct tree_buffer *b;

	if (root->cache_size < cache_max)

		return 0;

	list_for_each_safe(node, next, &root->cache) {

		b = list_entry(node, struct tree_buffer, cache);

		if (b->count == 1) {

			BUG_ON(!list_empty(&b->dirty));

			list_del_init(&b->cache);

			tree_block_release(root, b);

			if (root->cache_size < cache_max)

				return 0;

		}

	}

	return 0;

}



struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr)

{

	struct tree_buffer *buf;
@@ -30,10 +51,14 @@ struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr) 
		return buf;

	allocated_blocks++;

	buf->blocknr = blocknr;

	buf->count = 1;

	buf->count = 2;

	INIT_LIST_HEAD(&buf->dirty);

	free_some_buffers(root);

	radix_tree_preload(GFP_KERNEL);

	ret = radix_tree_insert(&root->cache_radix, blocknr, buf);

	radix_tree_preload_end();

	list_add_tail(&buf->cache, &root->cache);

	root->cache_size++;

	if (ret) {

		free(buf);

		return NULL;
@@ -57,7 +82,6 @@ struct tree_buffer *find_tree_block(struct ctree_root *root, u64 blocknr) 
	return buf;

}





struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)

{

	loff_t offset = blocknr * CTREE_BLOCKSIZE;
@@ -82,6 +106,24 @@ struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr) 
	return buf;

}



int dirty_tree_block(struct ctree_root *root, struct tree_buffer *buf)

{

	if (!list_empty(&buf->dirty))

		return 0;

	list_add_tail(&buf->dirty, &root->trans);

	buf->count++;

	return 0;

}



int clean_tree_block(struct ctree_root *root, struct tree_buffer *buf)

{

	if (!list_empty(&buf->dirty)) {

		list_del_init(&buf->dirty);

		tree_block_release(root, buf);

	}

	return 0;

}



int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)

{

	u64 blocknr = buf->blocknr;
@@ -96,9 +138,37 @@ int write_tree_block(struct ctree_root *root, struct tree_buffer *buf) 
	return 0;

}



static int __commit_transaction(struct ctree_root *root)

{

	struct tree_buffer *b;

	int ret = 0;

	int wret;

	while(!list_empty(&root->trans)) {

		b = list_entry(root->trans.next, struct tree_buffer, dirty);

		list_del_init(&b->dirty);

		wret = write_tree_block(root, b);

		if (wret)

			ret = wret;

		tree_block_release(root, b);

	}

	return ret;

}



int commit_transaction(struct ctree_root *root)

{

	int ret;

	ret = __commit_transaction(root);

	if (!ret && root != root->extent_root)

		ret = __commit_transaction(root->extent_root);

	BUG_ON(ret);

	return ret;

}



static int __setup_root(struct ctree_root *root, struct ctree_root *extent_root,

			struct ctree_root_info *info, int fp)

{

	INIT_LIST_HEAD(&root->trans);

	INIT_LIST_HEAD(&root->cache);

	root->fp = fp;

	root->node = NULL;

	root->node = read_tree_block(root, info->tree_root);
@@ -157,8 +227,23 @@ int write_ctree_super(struct ctree_root *root, struct ctree_super_block *s) 
	return 0;

}



static int drop_cache(struct ctree_root *root)

{

	while(!list_empty(&root->cache)) {

		struct tree_buffer *b = list_entry(root->cache.next,

						   struct tree_buffer, cache);

		list_del_init(&b->cache);

		tree_block_release(root, b);

	}

	return 0;

}

int close_ctree(struct ctree_root *root)

{

	drop_cache(root->extent_root);

	drop_cache(root);

	BUG_ON(!list_empty(&root->trans));

	BUG_ON(!list_empty(&root->extent_root->trans));



	close(root->fp);

	if (root->node)

		tree_block_release(root, root->node);
@@ -182,6 +267,8 @@ void tree_block_release(struct ctree_root *root, struct tree_buffer *buf) 
		free(buf);

		BUG_ON(allocated_blocks == 0);

		allocated_blocks--;

		BUG_ON(root->cache_size == 0);

		root->cache_size--;

	}

}

fs/btrfs/disk-io.h

+6 −0
Original line number Diff line number Diff line 
#ifndef __DISKIO__

#define __DISKIO__

#include "list.h"



struct tree_buffer {

	u64 blocknr;
@@ -8,11 +9,16 @@ struct tree_buffer { 
		struct node node;

		struct leaf leaf;

	};

	struct list_head dirty;

	struct list_head cache;

};



struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr);

struct tree_buffer *find_tree_block(struct ctree_root *root, u64 blocknr);

int write_tree_block(struct ctree_root *root, struct tree_buffer *buf);

int dirty_tree_block(struct ctree_root *root, struct tree_buffer *buf);

int clean_tree_block(struct ctree_root *root, struct tree_buffer *buf);

int commit_transaction(struct ctree_root *root);

struct ctree_root *open_ctree(char *filename, struct ctree_super_block *s);

int close_ctree(struct ctree_root *root);

void tree_block_release(struct ctree_root *root, struct tree_buffer *buf);

fs/btrfs/list.h

0 → 100644
+418 −0
Original line number Diff line number Diff line 
#ifndef _LINUX_LIST_H

#define _LINUX_LIST_H



#define LIST_POISON1  ((void *) 0x00100100)

#define LIST_POISON2  ((void *) 0x00200200)



/*

 * Simple doubly linked list implementation.

 *

 * Some of the internal functions ("__xxx") are useful when

 * manipulating whole lists rather than single entries, as

 * sometimes we already know the next/prev entries and we can

 * generate better code by using them directly rather than

 * using the generic single-entry routines.

 */



struct list_head {

	struct list_head *next, *prev;

};



#define LIST_HEAD_INIT(name) { &(name), &(name) }



#define LIST_HEAD(name) \

	struct list_head name = LIST_HEAD_INIT(name)



static inline void INIT_LIST_HEAD(struct list_head *list)

{

	list->next = list;

	list->prev = list;

}



/*

 * Insert a new entry between two known consecutive entries.

 *

 * This is only for internal list manipulation where we know

 * the prev/next entries already!

 */

#ifndef CONFIG_DEBUG_LIST

static inline void __list_add(struct list_head *new,

			      struct list_head *prev,

			      struct list_head *next)

{

	next->prev = new;

	new->next = next;

	new->prev = prev;

	prev->next = new;

}

#else

extern void __list_add(struct list_head *new,

			      struct list_head *prev,

			      struct list_head *next);

#endif



/**

 * list_add - add a new entry

 * @new: new entry to be added

 * @head: list head to add it after

 *

 * Insert a new entry after the specified head.

 * This is good for implementing stacks.

 */

#ifndef CONFIG_DEBUG_LIST

static inline void list_add(struct list_head *new, struct list_head *head)

{

	__list_add(new, head, head->next);

}

#else

extern void list_add(struct list_head *new, struct list_head *head);

#endif





/**

 * list_add_tail - add a new entry

 * @new: new entry to be added

 * @head: list head to add it before

 *

 * Insert a new entry before the specified head.

 * This is useful for implementing queues.

 */

static inline void list_add_tail(struct list_head *new, struct list_head *head)

{

	__list_add(new, head->prev, head);

}



/*

 * Delete a list entry by making the prev/next entries

 * point to each other.

 *

 * This is only for internal list manipulation where we know

 * the prev/next entries already!

 */

static inline void __list_del(struct list_head * prev, struct list_head * next)

{

	next->prev = prev;

	prev->next = next;

}



/**

 * list_del - deletes entry from list.

 * @entry: the element to delete from the list.

 * Note: list_empty on entry does not return true after this, the entry is

 * in an undefined state.

 */

#ifndef CONFIG_DEBUG_LIST

static inline void list_del(struct list_head *entry)

{

	__list_del(entry->prev, entry->next);

	entry->next = LIST_POISON1;

	entry->prev = LIST_POISON2;

}

#else

extern void list_del(struct list_head *entry);

#endif



/**

 * list_replace - replace old entry by new one

 * @old : the element to be replaced

 * @new : the new element to insert

 * Note: if 'old' was empty, it will be overwritten.

 */

static inline void list_replace(struct list_head *old,

				struct list_head *new)

{

	new->next = old->next;

	new->next->prev = new;

	new->prev = old->prev;

	new->prev->next = new;

}



static inline void list_replace_init(struct list_head *old,

					struct list_head *new)

{

	list_replace(old, new);

	INIT_LIST_HEAD(old);

}

/**

 * list_del_init - deletes entry from list and reinitialize it.

 * @entry: the element to delete from the list.

 */

static inline void list_del_init(struct list_head *entry)

{

	__list_del(entry->prev, entry->next);

	INIT_LIST_HEAD(entry);

}



/**

 * list_move - delete from one list and add as another's head

 * @list: the entry to move

 * @head: the head that will precede our entry

 */

static inline void list_move(struct list_head *list, struct list_head *head)

{

        __list_del(list->prev, list->next);

        list_add(list, head);

}



/**

 * list_move_tail - delete from one list and add as another's tail

 * @list: the entry to move

 * @head: the head that will follow our entry

 */

static inline void list_move_tail(struct list_head *list,

				  struct list_head *head)

{

        __list_del(list->prev, list->next);

        list_add_tail(list, head);

}



/**

 * list_is_last - tests whether @list is the last entry in list @head

 * @list: the entry to test

 * @head: the head of the list

 */

static inline int list_is_last(const struct list_head *list,

				const struct list_head *head)

{

	return list->next == head;

}



/**

 * list_empty - tests whether a list is empty

 * @head: the list to test.

 */

static inline int list_empty(const struct list_head *head)

{

	return head->next == head;

}



/**

 * list_empty_careful - tests whether a list is empty and not being modified

 * @head: the list to test

 *

 * Description:

 * tests whether a list is empty _and_ checks that no other CPU might be

 * in the process of modifying either member (next or prev)

 *

 * NOTE: using list_empty_careful() without synchronization

 * can only be safe if the only activity that can happen

 * to the list entry is list_del_init(). Eg. it cannot be used

 * if another CPU could re-list_add() it.

 */

static inline int list_empty_careful(const struct list_head *head)

{

	struct list_head *next = head->next;

	return (next == head) && (next == head->prev);

}



static inline void __list_splice(struct list_head *list,

				 struct list_head *head)

{

	struct list_head *first = list->next;

	struct list_head *last = list->prev;

	struct list_head *at = head->next;



	first->prev = head;

	head->next = first;



	last->next = at;

	at->prev = last;

}



/**

 * list_splice - join two lists

 * @list: the new list to add.

 * @head: the place to add it in the first list.

 */

static inline void list_splice(struct list_head *list, struct list_head *head)

{

	if (!list_empty(list))

		__list_splice(list, head);

}



/**

 * list_splice_init - join two lists and reinitialise the emptied list.

 * @list: the new list to add.

 * @head: the place to add it in the first list.

 *

 * The list at @list is reinitialised

 */

static inline void list_splice_init(struct list_head *list,

				    struct list_head *head)

{

	if (!list_empty(list)) {

		__list_splice(list, head);

		INIT_LIST_HEAD(list);

	}

}



/**

 * list_entry - get the struct for this entry

 * @ptr:	the &struct list_head pointer.

 * @type:	the type of the struct this is embedded in.

 * @member:	the name of the list_struct within the struct.

 */

#define list_entry(ptr, type, member) \

	container_of(ptr, type, member)



/**

 * list_for_each	-	iterate over a list

 * @pos:	the &struct list_head to use as a loop cursor.

 * @head:	the head for your list.

 */

#define list_for_each(pos, head) \

	for (pos = (head)->next; prefetch(pos->next), pos != (head); \

        	pos = pos->next)



/**

 * __list_for_each	-	iterate over a list

 * @pos:	the &struct list_head to use as a loop cursor.

 * @head:	the head for your list.

 *

 * This variant differs from list_for_each() in that it's the

 * simplest possible list iteration code, no prefetching is done.

 * Use this for code that knows the list to be very short (empty

 * or 1 entry) most of the time.

 */

#define __list_for_each(pos, head) \

	for (pos = (head)->next; pos != (head); pos = pos->next)



/**

 * list_for_each_prev	-	iterate over a list backwards

 * @pos:	the &struct list_head to use as a loop cursor.

 * @head:	the head for your list.

 */

#define list_for_each_prev(pos, head) \

	for (pos = (head)->prev; prefetch(pos->prev), pos != (head); \

        	pos = pos->prev)



/**

 * list_for_each_safe - iterate over a list safe against removal of list entry

 * @pos:	the &struct list_head to use as a loop cursor.

 * @n:		another &struct list_head to use as temporary storage

 * @head:	the head for your list.

 */

#define list_for_each_safe(pos, n, head) \

	for (pos = (head)->next, n = pos->next; pos != (head); \

		pos = n, n = pos->next)



/**

 * list_for_each_entry	-	iterate over list of given type

 * @pos:	the type * to use as a loop cursor.

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 */

#define list_for_each_entry(pos, head, member)				\

	for (pos = list_entry((head)->next, typeof(*pos), member);	\

	     prefetch(pos->member.next), &pos->member != (head); 	\

	     pos = list_entry(pos->member.next, typeof(*pos), member))



/**

 * list_for_each_entry_reverse - iterate backwards over list of given type.

 * @pos:	the type * to use as a loop cursor.

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 */

#define list_for_each_entry_reverse(pos, head, member)			\

	for (pos = list_entry((head)->prev, typeof(*pos), member);	\

	     prefetch(pos->member.prev), &pos->member != (head); 	\

	     pos = list_entry(pos->member.prev, typeof(*pos), member))



/**

 * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue

 * @pos:	the type * to use as a start point

 * @head:	the head of the list

 * @member:	the name of the list_struct within the struct.

 *

 * Prepares a pos entry for use as a start point in list_for_each_entry_continue.

 */

#define list_prepare_entry(pos, head, member) \

	((pos) ? : list_entry(head, typeof(*pos), member))



/**

 * list_for_each_entry_continue - continue iteration over list of given type

 * @pos:	the type * to use as a loop cursor.

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 *

 * Continue to iterate over list of given type, continuing after

 * the current position.

 */

#define list_for_each_entry_continue(pos, head, member) 		\

	for (pos = list_entry(pos->member.next, typeof(*pos), member);	\

	     prefetch(pos->member.next), &pos->member != (head);	\

	     pos = list_entry(pos->member.next, typeof(*pos), member))



/**

 * list_for_each_entry_from - iterate over list of given type from the current point

 * @pos:	the type * to use as a loop cursor.

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 *

 * Iterate over list of given type, continuing from current position.

 */

#define list_for_each_entry_from(pos, head, member) 			\

	for (; prefetch(pos->member.next), &pos->member != (head);	\

	     pos = list_entry(pos->member.next, typeof(*pos), member))



/**

 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry

 * @pos:	the type * to use as a loop cursor.

 * @n:		another type * to use as temporary storage

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 */

#define list_for_each_entry_safe(pos, n, head, member)			\

	for (pos = list_entry((head)->next, typeof(*pos), member),	\

		n = list_entry(pos->member.next, typeof(*pos), member);	\

	     &pos->member != (head); 					\

	     pos = n, n = list_entry(n->member.next, typeof(*n), member))



/**

 * list_for_each_entry_safe_continue

 * @pos:	the type * to use as a loop cursor.

 * @n:		another type * to use as temporary storage

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 *

 * Iterate over list of given type, continuing after current point,

 * safe against removal of list entry.

 */

#define list_for_each_entry_safe_continue(pos, n, head, member) 		\

	for (pos = list_entry(pos->member.next, typeof(*pos), member), 		\

		n = list_entry(pos->member.next, typeof(*pos), member);		\

	     &pos->member != (head);						\

	     pos = n, n = list_entry(n->member.next, typeof(*n), member))



/**

 * list_for_each_entry_safe_from

 * @pos:	the type * to use as a loop cursor.

 * @n:		another type * to use as temporary storage

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 *

 * Iterate over list of given type from current point, safe against

 * removal of list entry.

 */

#define list_for_each_entry_safe_from(pos, n, head, member) 			\

	for (n = list_entry(pos->member.next, typeof(*pos), member);		\

	     &pos->member != (head);						\

	     pos = n, n = list_entry(n->member.next, typeof(*n), member))



/**

 * list_for_each_entry_safe_reverse

 * @pos:	the type * to use as a loop cursor.

 * @n:		another type * to use as temporary storage

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 *

 * Iterate backwards over list of given type, safe against removal

 * of list entry.

 */

#define list_for_each_entry_safe_reverse(pos, n, head, member)		\

	for (pos = list_entry((head)->prev, typeof(*pos), member),	\

		n = list_entry(pos->member.prev, typeof(*pos), member);	\

	     &pos->member != (head); 					\

	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))



#endif