4.19-stable review patch. If anyone has any objections, please let me know.
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From: Jiong Wu lohengrin1024@gmail.com
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: Jiong Wu Lohengrin1024@gmail.com Fixes: b305882fbc87 (mmc: core: optimize mmc_calc_max_discard) Cc: stable@vger.kernel.org # v4.17+ Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/mmc/core/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -2378,9 +2378,9 @@ unsigned int mmc_calc_max_discard(struct return card->pref_erase;
max_discard = mmc_do_calc_max_discard(card, MMC_ERASE_ARG); - if (max_discard && mmc_can_trim(card)) { + if (mmc_can_trim(card)) { max_trim = mmc_do_calc_max_discard(card, MMC_TRIM_ARG); - if (max_trim < max_discard) + if (max_trim < max_discard || max_discard == 0) max_discard = max_trim; } else if (max_discard < card->erase_size) { max_discard = 0;