[PATCH V8 06/13] sbitmap: add helper of sbitmap_calculate_shift
From: Ming Lei <hidden>
Date: 2021-02-07 09:22:58
Also in:
linux-block
Subsystem:
block layer, library code, the rest · Maintainers:
Jens Axboe, Andrew Morton, Linus Torvalds
Move code for calculating default shift into one public helper, which can be used for SCSI to calculate shift. Cc: Omar Sandoval <redacted> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Sumanesh Samanta <redacted> Cc: Ewan D. Milne <redacted> Reviewed-by: Hannes Reinecke <hare@suse.de> Tested-by: Sumanesh Samanta <redacted> Signed-off-by: Ming Lei <redacted> --- include/linux/sbitmap.h | 18 ++++++++++++++++++ lib/sbitmap.c | 16 +++------------- 2 files changed, 21 insertions(+), 13 deletions(-)
diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h
index c65ba887dcc3..3087e1f15fdd 100644
--- a/include/linux/sbitmap.h
+++ b/include/linux/sbitmap.h@@ -332,6 +332,24 @@ static inline int sbitmap_test_bit(struct sbitmap *sb, unsigned int bitnr) return test_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr)); } +static inline int sbitmap_calculate_shift(unsigned int depth) +{ + int shift = ilog2(BITS_PER_LONG); + + /* + * If the bitmap is small, shrink the number of bits per word so + * we spread over a few cachelines, at least. If less than 4 + * bits, just forget about it, it's not going to work optimally + * anyway. + */ + if (depth >= 4) { + while ((4U << shift) > depth) + shift--; + } + + return shift; +} + /** * sbitmap_show() - Dump &struct sbitmap information to a &struct seq_file. * @sb: Bitmap to show.
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 73da26ad021e..47b3691058eb 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c@@ -87,19 +87,9 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift, unsigned int bits_per_word; unsigned int i; - if (shift < 0) { - shift = ilog2(BITS_PER_LONG); - /* - * If the bitmap is small, shrink the number of bits per word so - * we spread over a few cachelines, at least. If less than 4 - * bits, just forget about it, it's not going to work optimally - * anyway. - */ - if (depth >= 4) { - while ((4U << shift) > depth) - shift--; - } - } + if (shift < 0) + shift = sbitmap_calculate_shift(depth); + bits_per_word = 1U << shift; if (bits_per_word > BITS_PER_LONG) return -EINVAL;
--
2.29.2