diff options
| author | David Sterba <dsterba@suse.com> | 2020-07-01 20:45:04 +0200 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2020-12-08 15:53:57 +0100 |
| commit | ab108d992b1248adfb7c13c1136cab59c944a98c (patch) | |
| tree | 3632b276548fe4abb15b73d675bfcf2c27805b2c /fs/btrfs/extent-tree.c | |
| parent | e940e9a7c793e3fffe6cdef4f849d696c57ed3f7 (diff) | |
| download | lwn-ab108d992b1248adfb7c13c1136cab59c944a98c.tar.gz lwn-ab108d992b1248adfb7c13c1136cab59c944a98c.zip | |
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 <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/extent-tree.c')
| -rw-r--r-- | fs/btrfs/extent-tree.c | 2 |
1 files changed, 1 insertions, 1 deletions
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; |