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>
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index a14dbca..cab0ffb 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -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) * \