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zram: fix broken page writeback 

commit 0d8359620d ("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 <minchan@kernel.org>
Reported-by: Amos Bianchi <amosbianchi@google.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: John Dias <joaodias@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Minchan Kim 2021-03-12 21:08:41 -08:00 committed by Linus Torvalds
parent 57e0076e65
commit 2766f18216
1 changed files with 3 additions and 3 deletions
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6
drivers/block/zram/zram_drv.c
View File

@ -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;