bitmap: fix memset optimization on big-endian systems

Commit 2a98dc028f91 ("include/linux/bitmap.h: turn bitmap_set and
bitmap_clear into memset when possible") introduced an optimization to
bitmap_{set,clear}() which uses memset() when the start and length are
constants aligned to a byte.

This is wrong on big-endian systems; our bitmaps are arrays of unsigned
long, so bit n is not at byte n / 8 in memory.  This was caught by the
Btrfs selftests, but the bitmap selftests also fail when run on a
big-endian machine.

We can still use memset if the start and length are aligned to an
unsigned long, so do that on big-endian.  The same problem applies to
the memcmp in bitmap_equal(), so fix it there, too.

Fixes: 2a98dc028f91 ("include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible")
Fixes: 2c6deb01525a ("bitmap: use memcmp optimisation in more situations")
Cc: [email protected]
Reported-by: "Erhard F." <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Signed-off-by: Omar Sandoval <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions