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Commit 4f2de97a authored by Josef Bacik's avatar Josef Bacik Committed by Chris Mason
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Btrfs: set page->private to the eb 



We spend a lot of time looking up extent buffers from pages when we could just
store the pointer to the eb the page is associated with in page->private.  This
patch does just that, and it makes things a little simpler and reduces a bit of
CPU overhead involved with doing metadata IO.  Thanks,

Signed-off-by: default avatarJosef Bacik <josef@redhat.com>
parent 727011e0

fs/btrfs/disk-io.c

+23 −68
Original line number Diff line number Diff line
@@ -403,39 +403,28 @@ static int csum_dirty_buffer(struct btrfs_root *root, struct page *page) 
	struct extent_io_tree *tree;

	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;

	u64 found_start;

	unsigned long len;

	struct extent_buffer *eb;



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



	if (page->private == EXTENT_PAGE_PRIVATE)

		goto out;

	if (!page->private) {

		WARN_ON(1);

		goto out;

	}

	len = page->private >> 2;

	WARN_ON(len == 0);



	eb = find_extent_buffer(tree, start, len);

	eb = (struct extent_buffer *)page->private;

	if (page != eb->pages[0])

		return 0;



	found_start = btrfs_header_bytenr(eb);

	if (found_start != start) {

		WARN_ON(1);

		goto err;

		return 0;

	}

	if (eb->pages[0] != page) {

		WARN_ON(1);

		goto err;

		return 0;

	}

	if (!PageUptodate(page)) {

		WARN_ON(1);

		goto err;

		return 0;

	}

	csum_tree_block(root, eb, 0);

err:

	free_extent_buffer(eb);

out:

	return 0;

}
@@ -566,7 +555,6 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end, 
	struct extent_io_tree *tree;

	u64 found_start;

	int found_level;

	unsigned long len;

	struct extent_buffer *eb;

	struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;

	int ret = 0;
@@ -576,13 +564,8 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end, 
		goto out;



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

	len = page->private >> 2;

	eb = (struct extent_buffer *)page->private;



	eb = find_eb_for_page(tree, page, max(root->leafsize, root->nodesize));

	if (!eb) {

		ret = -EIO;

		goto out;

	}

	reads_done = atomic_dec_and_test(&eb->pages_reading);

	if (!reads_done)

		goto err;
@@ -631,7 +614,6 @@ err: 


	if (ret && eb)

		clear_extent_buffer_uptodate(tree, eb, NULL);

	free_extent_buffer(eb);

out:

	return ret;

}
@@ -640,31 +622,17 @@ static int btree_io_failed_hook(struct bio *failed_bio, 
			 struct page *page, u64 start, u64 end,

			 int mirror_num, struct extent_state *state)

{

	struct extent_io_tree *tree;

	unsigned long len;

	struct extent_buffer *eb;

	struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;



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

	if (page->private == EXTENT_PAGE_PRIVATE)

		goto out;

	if (!page->private)

		goto out;



	len = page->private >> 2;

	WARN_ON(len == 0);



	eb = alloc_extent_buffer(tree, start, len);

	if (eb == NULL)

		goto out;

	eb = (struct extent_buffer *)page->private;

	if (page != eb->pages[0])

		return -EIO;



	if (test_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) {

		clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags);

		btree_readahead_hook(root, eb, eb->start, -EIO);

	}

	free_extent_buffer(eb);



out:

	return -EIO;	/* we fixed nothing */

}
@@ -955,10 +923,8 @@ static int btree_readpage(struct file *file, struct page *page) 


static int btree_releasepage(struct page *page, gfp_t gfp_flags)

{

	struct extent_io_tree *tree;

	struct extent_map_tree *map;

	struct extent_buffer *eb;

	struct btrfs_root *root;

	struct extent_io_tree *tree;

	int ret;



	if (PageWriteback(page) || PageDirty(page))
@@ -967,13 +933,6 @@ static int btree_releasepage(struct page *page, gfp_t gfp_flags) 
	tree = &BTRFS_I(page->mapping->host)->io_tree;

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



	root = BTRFS_I(page->mapping->host)->root;

	if (page->private == EXTENT_PAGE_PRIVATE) {

		eb = find_eb_for_page(tree, page, max(root->leafsize, root->nodesize));

		free_extent_buffer(eb);

		if (eb)

			return 0;

	}

	/*

	 * We need to mask out eg. __GFP_HIGHMEM and __GFP_DMA32 as we're doing

	 * slab allocation from alloc_extent_state down the callchain where
@@ -985,14 +944,7 @@ static int btree_releasepage(struct page *page, gfp_t gfp_flags) 
	if (!ret)

		return 0;



	ret = try_release_extent_buffer(tree, page);

	if (ret == 1) {

		ClearPagePrivate(page);

		set_page_private(page, 0);

		page_cache_release(page);

	}



	return ret;

	return try_release_extent_buffer(tree, page);

}



static void btree_invalidatepage(struct page *page, unsigned long offset)
@@ -3219,17 +3171,21 @@ static int btree_lock_page_hook(struct page *page, void *data, 
{

	struct inode *inode = page->mapping->host;

	struct btrfs_root *root = BTRFS_I(inode)->root;

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

	struct extent_buffer *eb;

	unsigned long len;

	u64 bytenr = page_offset(page);



	if (page->private == EXTENT_PAGE_PRIVATE)

	/*

	 * We culled this eb but the page is still hanging out on the mapping,

	 * carry on.

	 */

	if (!PagePrivate(page))

		goto out;



	len = page->private >> 2;

	eb = find_extent_buffer(io_tree, bytenr, len);

	if (!eb)

	eb = (struct extent_buffer *)page->private;

	if (!eb) {

		WARN_ON(1);

		goto out;

	}

	if (page != eb->pages[0])

		goto out;



	if (!btrfs_try_tree_write_lock(eb)) {
@@ -3248,7 +3204,6 @@ static int btree_lock_page_hook(struct page *page, void *data, 
	}



	btrfs_tree_unlock(eb);

	free_extent_buffer(eb);

out:

	if (!trylock_page(page)) {

		flush_fn(data);

fs/btrfs/extent_io.c

+67 −25
Original line number Diff line number Diff line
@@ -2473,19 +2473,24 @@ static int submit_extent_page(int rw, struct extent_io_tree *tree, 
	return ret;

}



void set_page_extent_mapped(struct page *page)

void attach_extent_buffer_page(struct extent_buffer *eb, struct page *page)

{

	if (!PagePrivate(page)) {

		SetPagePrivate(page);

		page_cache_get(page);

		set_page_private(page, EXTENT_PAGE_PRIVATE);

		set_page_private(page, (unsigned long)eb);

	} else {

		WARN_ON(page->private != (unsigned long)eb);

	}

}



static void set_page_extent_head(struct page *page, unsigned long len)

void set_page_extent_mapped(struct page *page)

{

	WARN_ON(!PagePrivate(page));

	set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2);

	if (!PagePrivate(page)) {

		SetPagePrivate(page);

		page_cache_get(page);

		set_page_private(page, EXTENT_PAGE_PRIVATE);

	}

}



/*
@@ -3585,6 +3590,7 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, 
		return NULL;

	eb->start = start;

	eb->len = len;

	eb->tree = tree;

	rwlock_init(&eb->lock);

	atomic_set(&eb->write_locks, 0);

	atomic_set(&eb->read_locks, 0);
@@ -3637,8 +3643,31 @@ static void btrfs_release_extent_buffer_page(struct extent_buffer *eb, 
	do {

		index--;

		page = extent_buffer_page(eb, index);

		if (page)

		if (page) {

			spin_lock(&page->mapping->private_lock);

			/*

			 * We do this since we'll remove the pages after we've

			 * removed the eb from the radix tree, so we could race

			 * and have this page now attached to the new eb.  So

			 * only clear page_private if it's still connected to

			 * this eb.

			 */

			if (PagePrivate(page) &&

			    page->private == (unsigned long)eb) {

				/*

				 * We need to make sure we haven't be attached

				 * to a new eb.

				 */

				ClearPagePrivate(page);

				set_page_private(page, 0);

				/* One for the page private */

				page_cache_release(page);

			}

			spin_unlock(&page->mapping->private_lock);



			/* One for when we alloced the page */

			page_cache_release(page);

		}

	} while (index != start_idx);

}
@@ -3683,6 +3712,32 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, 
			WARN_ON(1);

			goto free_eb;

		}



		spin_lock(&mapping->private_lock);

		if (PagePrivate(p)) {

			/*

			 * We could have already allocated an eb for this page

			 * and attached one so lets see if we can get a ref on

			 * the existing eb, and if we can we know it's good and

			 * we can just return that one, else we know we can just

			 * overwrite page->private.

			 */

			exists = (struct extent_buffer *)p->private;

			if (atomic_inc_not_zero(&exists->refs)) {

				spin_unlock(&mapping->private_lock);

				unlock_page(p);

				goto free_eb;

			}



			/* 

			 * Do this so attach doesn't complain and we need to

			 * drop the ref the old guy had.

			 */

			ClearPagePrivate(p);

			page_cache_release(p);

		}

		attach_extent_buffer_page(eb, p);

		spin_unlock(&mapping->private_lock);

		mark_page_accessed(p);

		eb->pages[i] = p;

		if (!PageUptodate(p))
@@ -3705,7 +3760,6 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, 
	if (ret == -EEXIST) {

		exists = radix_tree_lookup(&tree->buffer,

						start >> PAGE_CACHE_SHIFT);

		/* add one reference for the caller */

		atomic_inc(&exists->refs);

		spin_unlock(&tree->buffer_lock);

		radix_tree_preload_end();
@@ -3725,12 +3779,9 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, 
	 * after the extent buffer is in the radix tree so

	 * it doesn't get lost

	 */

	set_page_extent_mapped(eb->pages[0]);

	set_page_extent_head(eb->pages[0], eb->len);

	SetPageChecked(eb->pages[0]);

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

		p = extent_buffer_page(eb, i);

		set_page_extent_mapped(p);

		ClearPageChecked(p);

		unlock_page(p);

	}
@@ -3794,10 +3845,6 @@ int clear_extent_buffer_dirty(struct extent_io_tree *tree, 
		lock_page(page);

		WARN_ON(!PagePrivate(page));



		set_page_extent_mapped(page);

		if (i == 0)

			set_page_extent_head(page, eb->len);



		clear_page_dirty_for_io(page);

		spin_lock_irq(&page->mapping->tree_lock);

		if (!PageDirty(page)) {
@@ -4010,9 +4057,6 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, 
	atomic_set(&eb->pages_reading, num_reads);

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

		page = extent_buffer_page(eb, i);

		set_page_extent_mapped(page);

		if (i == 0)

			set_page_extent_head(page, eb->len);

		if (!PageUptodate(page)) {

			ClearPageError(page);

			err = __extent_read_full_page(tree, page,
@@ -4395,22 +4439,19 @@ static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head) 
	struct extent_buffer *eb =

			container_of(head, struct extent_buffer, rcu_head);



	btrfs_release_extent_buffer(eb);

	__free_extent_buffer(eb);

}



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

{

	u64 start = page_offset(page);

	struct extent_buffer *eb;

	struct extent_buffer *eb = (struct extent_buffer *)page->private;

	int ret = 1;



	spin_lock(&tree->buffer_lock);

	eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);

	if (!eb) {

		spin_unlock(&tree->buffer_lock);

		return ret;

	}

	if (!PagePrivate(page) || !eb)

		return 1;



	spin_lock(&tree->buffer_lock);

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

	    test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {

		ret = 0;
@@ -4426,6 +4467,7 @@ int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page) 
		goto out;

	}

	radix_tree_delete(&tree->buffer, start >> PAGE_CACHE_SHIFT);

	btrfs_release_extent_buffer_page(eb, 0);

out:

	spin_unlock(&tree->buffer_lock);

fs/btrfs/extent_io.h

+1 −0
Original line number Diff line number Diff line
@@ -127,6 +127,7 @@ struct extent_buffer { 
	unsigned long map_start;

	unsigned long map_len;

	unsigned long bflags;

	struct extent_io_tree *tree;

	atomic_t refs;

	atomic_t pages_reading;

	struct list_head leak_list;