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: Josef Bacik <josef@redhat.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 68fc93e..bc88649 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -403,39 +403,28 @@
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 @@
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 @@
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 @@
if (ret && eb)
clear_extent_buffer_uptodate(tree, eb, NULL);
- free_extent_buffer(eb);
out:
return ret;
}
@@ -640,31 +622,17 @@
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_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 @@
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 @@
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 @@
{
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 @@
}
btrfs_tree_unlock(eb);
- free_extent_buffer(eb);
out:
if (!trylock_page(page)) {
flush_fn(data);
