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| 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/ctree.h | |
| parent | e940e9a7c793e3fffe6cdef4f849d696c57ed3f7 (diff) | |
| download | linux-ab108d992b1248adfb7c13c1136cab59c944a98c.tar.bz2 | |
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/ctree.h')
| -rw-r--r-- | fs/btrfs/ctree.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index b1b6d9a69b99..2bfad194bf06 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -935,6 +935,8 @@ struct btrfs_fs_info { /* Cached block sizes */ u32 nodesize; u32 sectorsize; + /* ilog2 of sectorsize, use to avoid 64bit division */ + u32 sectorsize_bits; u32 stripesize; /* Block groups and devices containing active swapfiles. */ |