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/file-item.c | |
| parent | e940e9a7c793e3fffe6cdef4f849d696c57ed3f7 (diff) | |
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/file-item.c')
| -rw-r--r-- | fs/btrfs/file-item.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c index 816f57d52fc9..81a318a92418 100644 --- a/fs/btrfs/file-item.c +++ b/fs/btrfs/file-item.c @@ -369,7 +369,7 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, * a single leaf so it will also fit inside a u32 */ diff = disk_bytenr - item_start_offset; - diff = diff / fs_info->sectorsize; + diff = diff >> fs_info->sectorsize_bits; diff = diff * csum_size; count = min_t(int, nblocks, (item_last_offset - disk_bytenr) >> inode->i_sb->s_blocksize_bits); |