Btrfs: extent_io and extent_state optimizations
The end_bio routines are changed to take a pointer to the extent state
struct, and the state tree is walked in order to set/clear appropriate
bits as IO completes. This greatly reduces the number of rbtree searches
done by the end_bio handlers, and reduces lock contention.
The extent_io releasepage function is changed to avoid expensive searches
for locked state.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4845512..bac8722 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -331,7 +331,8 @@
return ret;
}
-int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end)
+int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end,
+ struct extent_state *state)
{
size_t offset = start - ((u64)page->index << PAGE_CACHE_SHIFT);
struct inode *inode = page->mapping->host;
@@ -347,7 +348,12 @@
btrfs_test_flag(inode, NODATASUM))
return 0;
- ret = get_state_private(io_tree, start, &private);
+ if (state->start == start) {
+ private = state->private;
+ ret = 0;
+ } else {
+ ret = get_state_private(io_tree, start, &private);
+ }
local_irq_save(flags);
kaddr = kmap_atomic(page, KM_IRQ0);
if (ret) {
@@ -1830,7 +1836,7 @@
}
struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
- size_t page_offset, u64 start, u64 len,
+ size_t pg_offset, u64 start, u64 len,
int create)
{
int ret;
@@ -1865,7 +1871,10 @@
start, len, em->start, em->len);
WARN_ON(1);
}
- goto out;
+ if (em->block_start == EXTENT_MAP_INLINE && page)
+ free_extent_map(em);
+ else
+ goto out;
}
em = alloc_extent_map(GFP_NOFS);
if (!em) {
@@ -1930,6 +1939,7 @@
em->len = extent_end - extent_start;
goto insert;
} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+ u64 page_start;
unsigned long ptr;
char *map;
size_t size;
@@ -1959,16 +1969,17 @@
goto out;
}
- extent_offset = ((u64)page->index << PAGE_CACHE_SHIFT) -
- extent_start + page_offset;
- copy_size = min_t(u64, PAGE_CACHE_SIZE - page_offset,
+ page_start = page_offset(page) + pg_offset;
+ extent_offset = page_start - extent_start;
+ copy_size = min_t(u64, PAGE_CACHE_SIZE - pg_offset,
size - extent_offset);
em->start = extent_start + extent_offset;
- em->len = copy_size;
+ em->len = (copy_size + root->sectorsize - 1) &
+ ~((u64)root->sectorsize - 1);
map = kmap(page);
ptr = btrfs_file_extent_inline_start(item) + extent_offset;
if (create == 0 && !PageUptodate(page)) {
- read_extent_buffer(leaf, map + page_offset, ptr,
+ read_extent_buffer(leaf, map + pg_offset, ptr,
copy_size);
flush_dcache_page(page);
} else if (create && PageUptodate(page)) {
@@ -1980,7 +1991,7 @@
trans = btrfs_start_transaction(root, 1);
goto again;
}
- write_extent_buffer(leaf, map + page_offset, ptr,
+ write_extent_buffer(leaf, map + pg_offset, ptr,
copy_size);
btrfs_mark_buffer_dirty(leaf);
}
@@ -2077,7 +2088,7 @@
btrfs_get_extent);
}
-static int btrfs_releasepage(struct page *page, gfp_t unused_gfp_flags)
+static int btrfs_releasepage(struct page *page, gfp_t gfp_flags)
{
struct extent_io_tree *tree;
struct extent_map_tree *map;
@@ -2085,7 +2096,7 @@
tree = &BTRFS_I(page->mapping->host)->io_tree;
map = &BTRFS_I(page->mapping->host)->extent_tree;
- ret = try_release_extent_mapping(map, tree, page);
+ ret = try_release_extent_mapping(map, tree, page, gfp_flags);
if (ret == 1) {
ClearPagePrivate(page);
set_page_private(page, 0);