Commit 2306580a authored Mar 12, 2021 by Minchan Kim Committed by Greg Kroah-Hartman Mar 17, 2021

zram: fix return value on writeback_store

commit 57e0076e6575a7b7cef620a0bd2ee2549ef77818 upstream.

writeback_store's return value is overwritten by submit_bio_wait's return
value.  Thus, writeback_store will return zero since there was no IO
error.  In the end, write syscall from userspace will see the zero as
return value, which could make the process stall to keep trying the write
until it will succeed.

Link: https://lkml.kernel.org/r/20210312173949.2197662-1-minchan@kernel.org


Fixes: 3b82a051c101("drivers/block/zram/zram_drv.c: fix error return codes not being returned in writeback_store")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Colin Ian King <colin.king@canonical.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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 29e28a13

drivers/block/zram/zram_drv.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -627,7 +627,7 @@ static ssize_t writeback_store(struct device *dev,
		struct bio_vec bio_vec;
		struct page *page;
		ssize_t ret = len;
		int mode;
		int mode, err;
		unsigned long blk_idx = 0;

		if (sysfs_streq(buf, "idle"))
		@@ -719,12 +719,17 @@ static ssize_t writeback_store(struct device *dev,
		* XXX: A single page IO would be inefficient for write
		* but it would be not bad as starter.
		*/
		ret = submit_bio_wait(&bio);
		if (ret) {
		err = submit_bio_wait(&bio);
		if (err) {
		zram_slot_lock(zram, index);
		zram_clear_flag(zram, index, ZRAM_UNDER_WB);
		zram_clear_flag(zram, index, ZRAM_IDLE);
		zram_slot_unlock(zram, index);
		/*
		* Return last IO error unless every IO were
		* not suceeded.
		*/
		ret = err;
		continue;
		}