[PATCH v3 0/4] lib/string_helpers: fix precision issues and introduce tests

From: Vitaly Kuznetsov
Date: Thu Oct 29 2015 - 12:30:58 EST


Linux always lies about your storage size when it has 4k sectors and its
size is big enough. E.g. a device with 8192 4k sectors will be reported as
"32.7 MB/32 MiB" while "33.5 MB/32 MiB" is expected. This series is
supposed to fix the issue by fixing calculation precision in
string_get_size() for all possible inputs.

PATCH 1/4 is a preparatory change, PATCH 2/4 adds additional protection
against blk_size=0 (nobody is supposed to call string_get_size() with
with blk_size=0, but better safe than sorry), PATCH 3/4 re-factors
string_get_size() fixing the issue, PATCH 4/4 introduces tests for
string_get_size().

PATCH 4/4 was previously sent as part of "lib/string_helpers.c: fix
infinite loop in string_get_size()" series but it is still not merged
upstream. In this submission I improve it and add additional tests to it.

Changes since v2:
- Separate blk_size check from Patch 3/4 to new Patch 2/4 [Andy Shevchenko]
- Slightly change the algorithm in Patch 3/4 [Rasmus Villemoes]

Vitaly Kuznetsov (4):
lib/string_helpers: change blk_size to u32 for string_get_size()
interface
lib/string_helpers.c: protect string_get_size() against blk_size=0
lib/string_helpers.c: don't lose precision in string_get_size()
lib/test-string_helpers.c: add string_get_size() tests

include/linux/string_helpers.h | 2 +-
lib/string_helpers.c | 38 ++++++++++++++-------------
lib/test-string_helpers.c | 58 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 79 insertions(+), 19 deletions(-)

--
2.4.3

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