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| author | Qu Wenruo <wqu@suse.com> | 2022-04-20 16:08:28 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2022-05-16 17:03:16 +0200 |
| commit | 719fae8920e4f42643ea306b95addb40bec87a25 (patch) | |
| tree | ed6dc04f9c54ee6f283be23dba4e5b9963ad9194 /fs/btrfs/volumes.c | |
| parent | f04fbcc64e4be16185151f9fca44ea1b3d074bd0 (diff) | |
| download | linux-719fae8920e4f42643ea306b95addb40bec87a25.tar.bz2 | |
btrfs: use ilog2() to replace if () branches for btrfs_bg_flags_to_raid_index()
In function btrfs_bg_flags_to_raid_index(), we use quite some if () to
convert the BTRFS_BLOCK_GROUP_* bits to a index number.
But the truth is, there is really no such need for so many branches at
all.
Since all BTRFS_BLOCK_GROUP_* flags are just one single bit set inside
BTRFS_BLOCK_GROUP_PROFILES_MASK, we can easily use ilog2() to calculate
their values.
This calculation has an anchor point, the lowest PROFILE bit, which is
RAID0.
Even it's fixed on-disk format and should never change, here I added
extra compile time checks to make it super safe:
1. Make sure RAID0 is always the lowest bit in PROFILE_MASK
This is done by finding the first (least significant) bit set of
RAID0 and PROFILE_MASK & ~RAID0.
2. Make sure RAID0 bit set beyond the highest bit of TYPE_MASK
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/volumes.c')
| -rw-r--r-- | fs/btrfs/volumes.c | 24 |
1 files changed, 6 insertions, 18 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 869acf5928af..58f3eece8a48 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -164,24 +164,12 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = { */ enum btrfs_raid_types __attribute_const__ btrfs_bg_flags_to_raid_index(u64 flags) { - if (flags & BTRFS_BLOCK_GROUP_RAID10) - return BTRFS_RAID_RAID10; - else if (flags & BTRFS_BLOCK_GROUP_RAID1) - return BTRFS_RAID_RAID1; - else if (flags & BTRFS_BLOCK_GROUP_RAID1C3) - return BTRFS_RAID_RAID1C3; - else if (flags & BTRFS_BLOCK_GROUP_RAID1C4) - return BTRFS_RAID_RAID1C4; - else if (flags & BTRFS_BLOCK_GROUP_DUP) - return BTRFS_RAID_DUP; - else if (flags & BTRFS_BLOCK_GROUP_RAID0) - return BTRFS_RAID_RAID0; - else if (flags & BTRFS_BLOCK_GROUP_RAID5) - return BTRFS_RAID_RAID5; - else if (flags & BTRFS_BLOCK_GROUP_RAID6) - return BTRFS_RAID_RAID6; - - return BTRFS_RAID_SINGLE; /* BTRFS_BLOCK_GROUP_SINGLE */ + const u64 profile = (flags & BTRFS_BLOCK_GROUP_PROFILE_MASK); + + if (!profile) + return BTRFS_RAID_SINGLE; + + return BTRFS_BG_FLAG_TO_INDEX(profile); } const char *btrfs_bg_type_to_raid_name(u64 flags) |