mmc:fix a bug when max_discard is 0
commit d4721339dcca7def04909a8e60da43c19a24d8bf upstream. The original purpose of the code I fix is to replace max_discard with max_trim if max_trim is less than max_discard. When max_discard is 0 we should replace max_discard with max_trim as well, because max_discard equals 0 happens only when the max_do_calc_max_discard process is overflowed, so if mmc_can_trim(card) is true, max_discard should be replaced by an available max_trim. However, in the original code, there are two lines of code interfere the right process. 1) if (max_discard && mmc_can_trim(card)) when max_discard is 0, it skips the process checking if max_discard needs to be replaced with max_trim. 2) if (max_trim < max_discard) the condition is false when max_discard is 0. it also skips the process that replaces max_discard with max_trim, in fact, we should replace the 0-valued max_discard with max_trim. Signed-off-by: NJiong Wu <Lohengrin1024@gmail.com> Fixes: b305882f (mmc: core: optimize mmc_calc_max_discard) Cc: stable@vger.kernel.org # v4.17+ Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org> Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
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