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Commit 6af118ce authored by Chris Mason's avatar Chris Mason
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Btrfs: Index extent buffers in an rbtree 



Before, extent buffers were a temporary object, meant to map a number of pages
at once and collect operations on them.

But, a few extra fields have crept in, and they are also the best place to
store a per-tree block lock field as well.  This commit puts the extent
buffers into an rbtree, and ensures a single extent buffer for each
tree block.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 4a096752

fs/btrfs/disk-io.c

+9 −17
Original line number Diff line number Diff line
@@ -381,7 +381,6 @@ int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end, 


	end = min_t(u64, eb->len, PAGE_CACHE_SIZE);

	end = eb->start + end - 1;

	release_extent_buffer_tail_pages(eb);

err:

	free_extent_buffer(eb);

out:
@@ -563,21 +562,21 @@ static int btree_releasepage(struct page *page, gfp_t gfp_flags) 
	struct extent_map_tree *map;

	int ret;



	if (page_count(page) > 3) {

		/* once for page->private, once for the caller, once

		 * once for the page cache

		 */

		return 0;

	}

	tree = &BTRFS_I(page->mapping->host)->io_tree;

	map = &BTRFS_I(page->mapping->host)->extent_tree;



	ret = try_release_extent_state(map, tree, page, gfp_flags);

	if (!ret) {

		return 0;

	}



	ret = try_release_extent_buffer(tree, page);

	if (ret == 1) {

		invalidate_extent_lru(tree, page_offset(page), PAGE_CACHE_SIZE);

		ClearPagePrivate(page);

		set_page_private(page, 0);

		page_cache_release(page);

	}



	return ret;

}
@@ -588,7 +587,8 @@ static void btree_invalidatepage(struct page *page, unsigned long offset) 
	extent_invalidatepage(tree, page, offset);

	btree_releasepage(page, GFP_NOFS);

	if (PagePrivate(page)) {

		invalidate_extent_lru(tree, page_offset(page), PAGE_CACHE_SIZE);

		printk("warning page private not zero on page %Lu\n",

		       page_offset(page));

		ClearPagePrivate(page);

		set_page_private(page, 0);

		page_cache_release(page);
@@ -1456,7 +1456,6 @@ struct btrfs_root *open_ctree(struct super_block *sb, 
	free_extent_buffer(tree_root->node);

fail_sys_array:

fail_sb_buffer:

	extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);

	btrfs_stop_workers(&fs_info->fixup_workers);

	btrfs_stop_workers(&fs_info->workers);

	btrfs_stop_workers(&fs_info->endio_workers);
@@ -1705,13 +1704,6 @@ int close_ctree(struct btrfs_root *root) 


	filemap_write_and_wait(fs_info->btree_inode->i_mapping);



	extent_io_tree_empty_lru(&fs_info->free_space_cache);

	extent_io_tree_empty_lru(&fs_info->block_group_cache);

	extent_io_tree_empty_lru(&fs_info->pinned_extents);

	extent_io_tree_empty_lru(&fs_info->pending_del);

	extent_io_tree_empty_lru(&fs_info->extent_ins);

	extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);



	truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);



	btrfs_stop_workers(&fs_info->fixup_workers);

fs/btrfs/extent_io.c

+116 −193
Original line number Diff line number Diff line
@@ -91,29 +91,16 @@ void extent_io_tree_init(struct extent_io_tree *tree, 
			  struct address_space *mapping, gfp_t mask)

{

	tree->state.rb_node = NULL;

	tree->buffer.rb_node = NULL;

	tree->ops = NULL;

	tree->dirty_bytes = 0;

	spin_lock_init(&tree->lock);

	spin_lock_init(&tree->lru_lock);

	spin_lock_init(&tree->buffer_lock);

	tree->mapping = mapping;

	INIT_LIST_HEAD(&tree->buffer_lru);

	tree->lru_size = 0;

	tree->last = NULL;

}

EXPORT_SYMBOL(extent_io_tree_init);



void extent_io_tree_empty_lru(struct extent_io_tree *tree)

{

	struct extent_buffer *eb;

	while(!list_empty(&tree->buffer_lru)) {

		eb = list_entry(tree->buffer_lru.next, struct extent_buffer,

				lru);

		list_del_init(&eb->lru);

		free_extent_buffer(eb);

	}

}

EXPORT_SYMBOL(extent_io_tree_empty_lru);



struct extent_state *alloc_extent_state(gfp_t mask)

{

	struct extent_state *state;
@@ -245,6 +232,50 @@ static inline struct rb_node *tree_search(struct extent_io_tree *tree, 
	return ret;

}



static struct extent_buffer *buffer_tree_insert(struct extent_io_tree *tree,

					  u64 offset, struct rb_node *node)

{

	struct rb_root *root = &tree->buffer;

	struct rb_node ** p = &root->rb_node;

	struct rb_node * parent = NULL;

	struct extent_buffer *eb;



	while(*p) {

		parent = *p;

		eb = rb_entry(parent, struct extent_buffer, rb_node);



		if (offset < eb->start)

			p = &(*p)->rb_left;

		else if (offset > eb->start)

			p = &(*p)->rb_right;

		else

			return eb;

	}



	rb_link_node(node, parent, p);

	rb_insert_color(node, root);

	return NULL;

}



static struct extent_buffer *buffer_search(struct extent_io_tree *tree,

					   u64 offset)

{

	struct rb_root *root = &tree->buffer;

	struct rb_node * n = root->rb_node;

	struct extent_buffer *eb;



	while(n) {

		eb = rb_entry(n, struct extent_buffer, rb_node);

		if (offset < eb->start)

			n = n->rb_left;

		else if (offset > eb->start)

			n = n->rb_right;

		else

			return eb;

	}

	return NULL;

}



/*

 * utility function to look for merge candidates inside a given range.

 * Any extents with matching state are merged together into a single
@@ -1817,9 +1848,8 @@ void set_page_extent_mapped(struct page *page) 
{

	if (!PagePrivate(page)) {

		SetPagePrivate(page);

		WARN_ON(!page->mapping->a_ops->invalidatepage);

		set_page_private(page, EXTENT_PAGE_PRIVATE);

		page_cache_get(page);

		set_page_private(page, EXTENT_PAGE_PRIVATE);

	}

}
@@ -2627,51 +2657,6 @@ sector_t extent_bmap(struct address_space *mapping, sector_t iblock, 
	return sector;

}



static int add_lru(struct extent_io_tree *tree, struct extent_buffer *eb)

{

	if (list_empty(&eb->lru)) {

		extent_buffer_get(eb);

		list_add(&eb->lru, &tree->buffer_lru);

		tree->lru_size++;

		if (tree->lru_size >= BUFFER_LRU_MAX) {

			struct extent_buffer *rm;

			rm = list_entry(tree->buffer_lru.prev,

					struct extent_buffer, lru);

			tree->lru_size--;

			list_del_init(&rm->lru);

			free_extent_buffer(rm);

		}

	} else

		list_move(&eb->lru, &tree->buffer_lru);

	return 0;

}

static struct extent_buffer *find_lru(struct extent_io_tree *tree,

				      u64 start, unsigned long len)

{

	struct list_head *lru = &tree->buffer_lru;

	struct list_head *cur = lru->next;

	struct extent_buffer *eb;



	if (list_empty(lru))

		return NULL;



	do {

		eb = list_entry(cur, struct extent_buffer, lru);

		if (eb->start == start && eb->len == len) {

			extent_buffer_get(eb);

			return eb;

		}

		cur = cur->next;

	} while (cur != lru);

	return NULL;

}



static inline unsigned long num_extent_pages(u64 start, u64 len)

{

	return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -

		(start >> PAGE_CACHE_SHIFT);

}



static inline struct page *extent_buffer_page(struct extent_buffer *eb,

					      unsigned long i)

{
@@ -2688,44 +2673,10 @@ static inline struct page *extent_buffer_page(struct extent_buffer *eb, 
	return p;

}



int release_extent_buffer_tail_pages(struct extent_buffer *eb)

{

	unsigned long num_pages = num_extent_pages(eb->start, eb->len);

	struct page *page;

	unsigned long i;



	if (num_pages == 1)

		return 0;

	for (i = 1; i < num_pages; i++) {

		page = extent_buffer_page(eb, i);

		page_cache_release(page);

	}

	return 0;

}





int invalidate_extent_lru(struct extent_io_tree *tree, u64 start,

			  unsigned long len)

static inline unsigned long num_extent_pages(u64 start, u64 len)

{

	struct list_head *lru = &tree->buffer_lru;

	struct list_head *cur = lru->next;

	struct extent_buffer *eb;

	int found = 0;



	spin_lock(&tree->lru_lock);

	if (list_empty(lru))

		goto out;



	do {

		eb = list_entry(cur, struct extent_buffer, lru);

		if (eb->start <= start && eb->start + eb->len > start) {

			eb->flags &= ~EXTENT_UPTODATE;

		}

		cur = cur->next;

	} while (cur != lru);

out:

	spin_unlock(&tree->lru_lock);

	return found;

	return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -

		(start >> PAGE_CACHE_SHIFT);

}



static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
@@ -2736,15 +2687,7 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, 
	struct extent_buffer *eb = NULL;

	unsigned long flags;



	spin_lock(&tree->lru_lock);

	eb = find_lru(tree, start, len);

	spin_unlock(&tree->lru_lock);

	if (eb) {

		return eb;

	}



	eb = kmem_cache_zalloc(extent_buffer_cache, mask);

	INIT_LIST_HEAD(&eb->lru);

	eb->start = start;

	eb->len = len;

	spin_lock_irqsave(&leak_lock, flags);
@@ -2773,17 +2716,24 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, 
	unsigned long i;

	unsigned long index = start >> PAGE_CACHE_SHIFT;

	struct extent_buffer *eb;

	struct extent_buffer *exists = NULL;

	struct page *p;

	struct address_space *mapping = tree->mapping;

	int uptodate = 1;



	spin_lock(&tree->buffer_lock);

	eb = buffer_search(tree, start);

	if (eb) {

		atomic_inc(&eb->refs);

		spin_unlock(&tree->buffer_lock);

		return eb;

	}

	spin_unlock(&tree->buffer_lock);



	eb = __alloc_extent_buffer(tree, start, len, mask);

	if (!eb)

		return NULL;



	if (eb->flags & EXTENT_BUFFER_FILLED)

		goto lru_add;



	if (page0) {

		eb->first_page = page0;

		i = 1;
@@ -2800,7 +2750,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, 
		p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);

		if (!p) {

			WARN_ON(1);

			goto fail;

			goto free_eb;

		}

		set_page_extent_mapped(p);

		mark_page_accessed(p);
@@ -2818,25 +2768,28 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, 
		eb->flags |= EXTENT_UPTODATE;

	eb->flags |= EXTENT_BUFFER_FILLED;



lru_add:

	spin_lock(&tree->lru_lock);

	add_lru(tree, eb);

	spin_unlock(&tree->lru_lock);

	spin_lock(&tree->buffer_lock);

	exists = buffer_tree_insert(tree, start, &eb->rb_node);

	if (exists) {

		/* add one reference for the caller */

		atomic_inc(&exists->refs);

		spin_unlock(&tree->buffer_lock);

		goto free_eb;

	}

	spin_unlock(&tree->buffer_lock);



	/* add one reference for the tree */

	atomic_inc(&eb->refs);

	return eb;



fail:

	spin_lock(&tree->lru_lock);

	list_del_init(&eb->lru);

	spin_unlock(&tree->lru_lock);

free_eb:

	if (!atomic_dec_and_test(&eb->refs))

		return NULL;

	for (index = 1; index < i; index++) {

		return exists;

	for (index = 1; index < i; index++)

		page_cache_release(extent_buffer_page(eb, index));

	}

	if (i > 0)

	page_cache_release(extent_buffer_page(eb, 0));

	__free_extent_buffer(eb);

	return NULL;

	return exists;

}

EXPORT_SYMBOL(alloc_extent_buffer);
@@ -2844,89 +2797,27 @@ struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree, 
					 u64 start, unsigned long len,

					  gfp_t mask)

{

	unsigned long num_pages = num_extent_pages(start, len);

	unsigned long i;

	unsigned long index = start >> PAGE_CACHE_SHIFT;

	struct extent_buffer *eb;

	struct page *p;

	struct address_space *mapping = tree->mapping;

	int uptodate = 1;



	eb = __alloc_extent_buffer(tree, start, len, mask);

	if (!eb)

		return NULL;



	if (eb->flags & EXTENT_BUFFER_FILLED)

		goto lru_add;



	for (i = 0; i < num_pages; i++, index++) {

		p = find_get_page(mapping, index);

		if (!p) {

			goto fail;

		}

		if (TestSetPageLocked(p)) {

			page_cache_release(p);

			goto fail;

		}



		set_page_extent_mapped(p);

		mark_page_accessed(p);



		if (i == 0) {

			eb->first_page = p;

			set_page_extent_head(p, len);

		} else {

			set_page_private(p, EXTENT_PAGE_PRIVATE);

		}



		if (!PageUptodate(p))

			uptodate = 0;

		unlock_page(p);

	}

	if (uptodate)

		eb->flags |= EXTENT_UPTODATE;

	eb->flags |= EXTENT_BUFFER_FILLED;

	spin_lock(&tree->buffer_lock);

	eb = buffer_search(tree, start);

	if (eb)

		atomic_inc(&eb->refs);

	spin_unlock(&tree->buffer_lock);



lru_add:

	spin_lock(&tree->lru_lock);

	add_lru(tree, eb);

	spin_unlock(&tree->lru_lock);

	return eb;

fail:

	spin_lock(&tree->lru_lock);

	list_del_init(&eb->lru);

	spin_unlock(&tree->lru_lock);

	if (!atomic_dec_and_test(&eb->refs))

		return NULL;

	for (index = 1; index < i; index++) {

		page_cache_release(extent_buffer_page(eb, index));

	}

	if (i > 0)

		page_cache_release(extent_buffer_page(eb, 0));

	__free_extent_buffer(eb);

	return NULL;

}

EXPORT_SYMBOL(find_extent_buffer);



void free_extent_buffer(struct extent_buffer *eb)

{

	unsigned long i;

	unsigned long num_pages;



	if (!eb)

		return;



	if (!atomic_dec_and_test(&eb->refs))

		return;



	WARN_ON(!list_empty(&eb->lru));

	num_pages = num_extent_pages(eb->start, eb->len);



	for (i = 1; i < num_pages; i++) {

		page_cache_release(extent_buffer_page(eb, i));

	}

	page_cache_release(extent_buffer_page(eb, 0));

	__free_extent_buffer(eb);

	WARN_ON(1);

}

EXPORT_SYMBOL(free_extent_buffer);
@@ -3583,3 +3474,35 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, 
	}

}

EXPORT_SYMBOL(memmove_extent_buffer);



int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)

{

	u64 start = page_offset(page);

	struct extent_buffer *eb;

	int ret = 1;

	unsigned long i;

	unsigned long num_pages;



	spin_lock(&tree->buffer_lock);

	eb = buffer_search(tree, start);

	if (!eb)

		goto out;



	if (atomic_read(&eb->refs) > 1) {

		ret = 0;

		goto out;

	}

	/* at this point we can safely release the extent buffer */

	num_pages = num_extent_pages(eb->start, eb->len);

	for (i = 0; i < num_pages; i++) {

		struct page *page = extent_buffer_page(eb, i);

		page_cache_release(page);

	}

	rb_erase(&eb->rb_node, &tree->buffer);

	__free_extent_buffer(eb);

out:

	spin_unlock(&tree->buffer_lock);

	return ret;

}

EXPORT_SYMBOL(try_release_extent_buffer);

fs/btrfs/extent_io.h

+4 −7
Original line number Diff line number Diff line
@@ -54,13 +54,12 @@ struct extent_io_ops { 


struct extent_io_tree {

	struct rb_root state;

	struct rb_root buffer;

	struct address_space *mapping;

	u64 dirty_bytes;

	spinlock_t lock;

	spinlock_t buffer_lock;

	struct extent_io_ops *ops;

	spinlock_t lru_lock;

	struct list_head buffer_lru;

	int lru_size;

	struct extent_state *last;

};
@@ -87,10 +86,10 @@ struct extent_buffer { 
	unsigned long map_start;

	unsigned long map_len;

	struct page *first_page;

	struct list_head lru;

	atomic_t refs;

	int flags;

	struct list_head leak_list;

	struct rb_node rb_node;

};



struct extent_map_tree;
@@ -112,10 +111,10 @@ typedef struct extent_map *(get_extent_t)(struct inode *inode, 


void extent_io_tree_init(struct extent_io_tree *tree,

			  struct address_space *mapping, gfp_t mask);

void extent_io_tree_empty_lru(struct extent_io_tree *tree);

int try_release_extent_mapping(struct extent_map_tree *map,

			       struct extent_io_tree *tree, struct page *page,

			       gfp_t mask);

int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page);

int try_release_extent_state(struct extent_map_tree *map,

			     struct extent_io_tree *tree, struct page *page,

			     gfp_t mask);
@@ -241,8 +240,6 @@ int map_private_extent_buffer(struct extent_buffer *eb, unsigned long offset, 
		      unsigned long *map_start,

		      unsigned long *map_len, int km);

void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km);

int invalidate_extent_lru(struct extent_io_tree *tree, u64 start,

			  unsigned long len);

int release_extent_buffer_tail_pages(struct extent_buffer *eb);

int extent_range_uptodate(struct extent_io_tree *tree,

			  u64 start, u64 end);

fs/btrfs/inode.c

+0 −3
Original line number Diff line number Diff line
@@ -2670,7 +2670,6 @@ static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags) 
	map = &BTRFS_I(page->mapping->host)->extent_tree;

	ret = try_release_extent_mapping(map, tree, page, gfp_flags);

	if (ret == 1) {

		invalidate_extent_lru(tree, page_offset(page), PAGE_CACHE_SIZE);

		ClearPagePrivate(page);

		set_page_private(page, 0);

		page_cache_release(page);
@@ -2721,8 +2720,6 @@ static void btrfs_invalidatepage(struct page *page, unsigned long offset) 


	ClearPageChecked(page);

	if (PagePrivate(page)) {

		invalidate_extent_lru(tree, page_offset(page),

				      PAGE_CACHE_SIZE);

		ClearPagePrivate(page);

		set_page_private(page, 0);

		page_cache_release(page);