Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 19b6caf4 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: reduce extent_state lock contention for metadata 



For metadata buffers that don't straddle pages (all of them), btrfs
can safely use the page uptodate bits and extent_buffer uptodate bit
instead of needing to use the extent_state tree.

This greatly reduces contention on the state tree lock.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 31533fb2

fs/btrfs/extent_io.c

+41 −14
Original line number Diff line number Diff line
@@ -3268,6 +3268,22 @@ int set_extent_buffer_dirty(struct extent_io_tree *tree, 
	return was_dirty;

}



static int __eb_straddles_pages(u64 start, u64 len)

{

	if (len < PAGE_CACHE_SIZE)

		return 1;

	if (start & (PAGE_CACHE_SIZE - 1))

		return 1;

	if ((start + len) & (PAGE_CACHE_SIZE - 1))

		return 1;

	return 0;

}



static int eb_straddles_pages(struct extent_buffer *eb)

{

	return __eb_straddles_pages(eb->start, eb->len);

}



int clear_extent_buffer_uptodate(struct extent_io_tree *tree,

				struct extent_buffer *eb,

				struct extent_state **cached_state)
@@ -3279,8 +3295,10 @@ int clear_extent_buffer_uptodate(struct extent_io_tree *tree, 
	num_pages = num_extent_pages(eb->start, eb->len);

	clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);



	if (eb_straddles_pages(eb)) {

		clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,

				      cached_state, GFP_NOFS);

	}

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

		page = extent_buffer_page(eb, i);

		if (page)
@@ -3298,8 +3316,10 @@ int set_extent_buffer_uptodate(struct extent_io_tree *tree, 


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



	if (eb_straddles_pages(eb)) {

		set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,

				    NULL, GFP_NOFS);

	}

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

		page = extent_buffer_page(eb, i);

		if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
@@ -3322,9 +3342,12 @@ int extent_range_uptodate(struct extent_io_tree *tree, 
	int uptodate;

	unsigned long index;



	ret = test_range_bit(tree, start, end, EXTENT_UPTODATE, 1, NULL);

	if (__eb_straddles_pages(start, end - start + 1)) {

		ret = test_range_bit(tree, start, end,

				     EXTENT_UPTODATE, 1, NULL);

		if (ret)

			return 1;

	}

	while (start <= end) {

		index = start >> PAGE_CACHE_SHIFT;

		page = find_get_page(tree->mapping, index);
@@ -3352,10 +3375,12 @@ int extent_buffer_uptodate(struct extent_io_tree *tree, 
	if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))

		return 1;



	if (eb_straddles_pages(eb)) {

		ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1,

				   EXTENT_UPTODATE, 1, cached_state);

		if (ret)

			return ret;

	}



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

	for (i = 0; i < num_pages; i++) {
@@ -3388,10 +3413,12 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, 
	if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))

		return 0;



	if (eb_straddles_pages(eb)) {

		if (test_range_bit(tree, eb->start, eb->start + eb->len - 1,

				   EXTENT_UPTODATE, 1, NULL)) {

			return 0;

		}

	}



	if (start) {

		WARN_ON(start < eb->start);