Commit 7ca4be45 authored Jan 31, 2012 by Chris Mason

Btrfs: don't use crc items bigger than 4KB



With the big metadata blocks, we can have crc items
that are much bigger than a page.  There are a few
places that we try to kmalloc memory to hold the
items during a split.

Items bigger than 4KB don't really have a huge benefit
in efficiency, but they do trigger larger order allocations.
This commits changes the csums to make sure they stay under
4KB.  This is not a format change, just a #define to limit
huge items.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

parent 3c4bb26b

fs/btrfs/file-item.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -25,10 +25,12 @@
		#include "transaction.h"
		#include "print-tree.h"

		#define MAX_CSUM_ITEMS(r, size) ((((BTRFS_LEAF_DATA_SIZE(r) - \
		#define __MAX_CSUM_ITEMS(r, size) ((((BTRFS_LEAF_DATA_SIZE(r) - \
		sizeof(struct btrfs_item) * 2) / \
		size) - 1))

		#define MAX_CSUM_ITEMS(r, size) (min(__MAX_CSUM_ITEMS(r, size), PAGE_CACHE_SIZE))

		#define MAX_ORDERED_SUM_BYTES(r) ((PAGE_SIZE - \
		sizeof(struct btrfs_ordered_sum)) / \
		sizeof(struct btrfs_sector_sum) * \

Admin message