From: Minchan Kim Date: Sat, 13 Mar 2021 05:08:41 +0000 (-0800) Subject: zram: fix broken page writeback X-Git-Tag: v5.12-rc3~12^2 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=2766f1821600cc7562bae2128ad0b163f744c5d9;p=linux-2.6-block.git zram: fix broken page writeback commit 0d8359620d9b ("zram: support page writeback") introduced two problems. It overwrites writeback_store's return value as kstrtol's return value, which makes return value zero so user could see zero as return value of write syscall even though it wrote data successfully. It also breaks index value in the loop in that it doesn't increase the index any longer. It means it can write only first starting block index so user couldn't write all idle pages in the zram so lose memory saving chance. This patch fixes those issues. Link: https://lkml.kernel.org/r/20210312173949.2197662-2-minchan@kernel.org Fixes: 0d8359620d9b("zram: support page writeback") Signed-off-by: Minchan Kim Reported-by: Amos Bianchi Cc: Sergey Senozhatsky Cc: John Dias Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 63bbefdffc81..cf8deecc39ef 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -638,8 +638,8 @@ static ssize_t writeback_store(struct device *dev, if (strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1)) return -EINVAL; - ret = kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index); - if (ret || index >= nr_pages) + if (kstrtol(buf + sizeof(PAGE_WB_SIG) - 1, 10, &index) || + index >= nr_pages) return -EINVAL; nr_pages = 1; @@ -663,7 +663,7 @@ static ssize_t writeback_store(struct device *dev, goto release_init_lock; } - while (nr_pages--) { + for (; nr_pages != 0; index++, nr_pages--) { struct bio_vec bvec; bvec.bv_page = page;