Please, keep the author of the original change in the loop. James, what do you think?
On Sun, Apr 19, 2026 at 6:31 PM Shuvam Pandey <[email protected]> wrote: > > string_get_size() rounds the fractional part before formatting the > result. If that carry pushes the integer part to the unit divisor, the > helper still prints the old unit and produces strings like "1000 kB" > and "1024 KiB". > > That misformatted carry case comes from the arithmetic rounding added by > commit 564b026fbd0d ("string_helpers: fix precision loss for some > inputs"). The helper already rounds those values up numerically; it > just fails to renormalize them into the next unit before formatting. > > Renormalize the carried result into the next named unit so those cases > print as "1.00 MB" and "1.00 MiB" instead. Only do that when another > named unit exists, so the existing "UNK" fallback is preserved at the > top end. Extend the KUnit coverage around the first decimal and binary > boundaries, including adjacent values and non-byte block sizes that hit > the same carry path. > > Fixes: 564b026fbd0d ("string_helpers: fix precision loss for some inputs") > Signed-off-by: Shuvam Pandey <[email protected]> > --- > Changes in v2: > - correct the Fixes tag to 564b026fbd0d > - renormalize only when another named unit exists > - preserve the top-end UNK fallback > - add decimal and binary boundary/neighbor KUnit coverage > - add non-byte block-size cases that hit the same carry path > > lib/string_helpers.c | 12 ++++++++++++ > lib/tests/string_helpers_kunit.c | 25 +++++++++++++++++++++++++ > 2 files changed, 37 insertions(+) > > diff --git a/lib/string_helpers.c b/lib/string_helpers.c > index 169eaf5834949..bcabb24fe0dbf 100644 > --- a/lib/string_helpers.c > +++ b/lib/string_helpers.c > @@ -121,6 +121,18 @@ int string_get_size(u64 size, u64 blk_size, const enum > string_size_units units, > size += 1; > } > > + /* > + * Renormalize into the next named unit, but preserve the top-end > + * UNK fallback. After promotion the value is exactly 1 of the next > + * unit, so keep two fractional digits for the usual 1.00 formatting. > + */ > + if (size >= divisor[units_base] && i + 1 < ARRAY_SIZE(units_2)) { > + size = 1; > + remainder = 0; > + i++; > + j = 2; > + } > + > if (j) { > snprintf(tmp, sizeof(tmp), ".%03u", remainder); > tmp[j+1] = '\0'; > diff --git a/lib/tests/string_helpers_kunit.c > b/lib/tests/string_helpers_kunit.c > index c853046183d24..67822cb48fd15 100644 > --- a/lib/tests/string_helpers_kunit.c > +++ b/lib/tests/string_helpers_kunit.c > @@ -558,6 +558,31 @@ static void test_get_size(struct kunit *test) > /* weird block sizes */ > test_string_get_size_one(3000, 1900, "5.70 MB", "5.44 MiB"); > > + /* rounding carry into the next unit at the first decimal boundary */ > + test_string_get_size_one(999499, 1, "999 kB", "976 KiB"); > + test_string_get_size_one(999500, 1, "1.00 MB", "976 KiB"); > + test_string_get_size_one(999999, 1, "1.00 MB", "977 KiB"); > + test_string_get_size_one(1000000, 1, "1.00 MB", "977 KiB"); > + test_string_get_size_one(1000001, 1, "1.00 MB", "977 KiB"); > + > + /* rounding carry into the next unit at the first binary boundary */ > + test_string_get_size_one(1048063, 1, "1.05 MB", "1023 KiB"); > + test_string_get_size_one(1048064, 1, "1.05 MB", "1.00 MiB"); > + test_string_get_size_one(1048575, 1, "1.05 MB", "1.00 MiB"); > + test_string_get_size_one(1048576, 1, "1.05 MB", "1.00 MiB"); > + test_string_get_size_one(1048577, 1, "1.05 MB", "1.00 MiB"); > + > + /* values already in the next binary unit stay unchanged */ > + test_string_get_size_one(2097151, 1, "2.10 MB", "2.00 MiB"); > + test_string_get_size_one(2097152, 1, "2.10 MB", "2.00 MiB"); > + test_string_get_size_one(2097153, 1, "2.10 MB", "2.00 MiB"); > + > + /* non-byte block sizes hit the same carry path */ > + test_string_get_size_one(4997, 200, "999 kB", "976 KiB"); > + test_string_get_size_one(4998, 200, "1.00 MB", "976 KiB"); > + test_string_get_size_one(9981, 105, "1.05 MB", "1023 KiB"); > + test_string_get_size_one(9982, 105, "1.05 MB", "1.00 MiB"); > + > /* huge values */ > test_string_get_size_one(U64_MAX, 4096, "75.6 ZB", "64.0 ZiB"); > test_string_get_size_one(4096, U64_MAX, "75.6 ZB", "64.0 ZiB"); > -- > 2.50.1 (Apple Git-155) > -- With Best Regards, Andy Shevchenko
