提交 f1381ec5 编写于 作者: C Chunguang Xu 提交者: Zheng Zengkai

block: fix the problem of io_ticks becoming smaller

mainline inclusion
from mainline-v5.14-rc1
commit d80c228d
category: bugfix
bugzilla: 187475, https://gitee.com/openeuler/kernel/issues/I5ME0J
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d80c228d44640f0b47b57a2ca4afa26ef87e16b0

--------------------------------

On the IO submission path, blk_account_io_start() may interrupt
the system interruption. When the interruption returns, the value
of part->stamp may have been updated by other cores, so the time
value collected before the interruption may be less than part->
stamp. So when this happens, we should do nothing to make io_ticks
more accurate? For kernels less than 5.0, this may cause io_ticks
to become smaller, which in turn may cause abnormal ioutil values.
Signed-off-by: NChunguang Xu <brookxu@tencent.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/1625521646-1069-1-git-send-email-brookxu.cn@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

conflict:
	block/blk-core.c
Signed-off-by: NLi Nan <linan122@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
上级 7e352987
......@@ -1258,7 +1258,7 @@ void update_io_ticks(struct hd_struct *part, unsigned long now, bool end)
unsigned long stamp;
again:
stamp = READ_ONCE(part->stamp);
if (unlikely(stamp != now)) {
if (unlikely(time_after(now, stamp))) {
if (likely(cmpxchg(&part->stamp, stamp, now) == stamp))
__part_stat_add(part, io_ticks, end ? now - stamp : 1);
}
......
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