From ab108d992b1248adfb7c13c1136cab59c944a98c Mon Sep 17 00:00:00 2001 From: David Sterba Date: Wed, 1 Jul 2020 20:45:04 +0200 Subject: btrfs: use precalculated sectorsize_bits from fs_info We do a lot of calculations where we divide or multiply by sectorsize. We also know and make sure that sectorsize is a power of two, so this means all divisions can be turned to shifts and avoid eg. expensive u64/u32 divisions. The type is u32 as it's more register friendly on x86_64 compared to u8 and the resulting assembly is smaller (movzbl vs movl). There's also superblock s_blocksize_bits but it's usually one more pointer dereference farther than fs_info. Reviewed-by: Johannes Thumshirn Signed-off-by: David Sterba --- fs/btrfs/extent-tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/btrfs/extent-tree.c') diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index bac1eb17e498..14d5aaa28399 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2145,7 +2145,7 @@ u64 btrfs_csum_bytes_to_leaves(struct btrfs_fs_info *fs_info, u64 csum_bytes) csum_size = BTRFS_MAX_ITEM_SIZE(fs_info); num_csums_per_leaf = div64_u64(csum_size, (u64)btrfs_super_csum_size(fs_info->super_copy)); - num_csums = div64_u64(csum_bytes, fs_info->sectorsize); + num_csums = csum_bytes >> fs_info->sectorsize_bits; num_csums += num_csums_per_leaf - 1; num_csums = div64_u64(num_csums, num_csums_per_leaf); return num_csums; -- cgit v1.2.3