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From c07068266b41450ca6821ee0a1a3adf34206015f Mon Sep 17 00:00:00 2001
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From: Kazuhito Hagio <k-hagio-ab@nec.com>
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Date: Fri, 10 Jun 2022 15:21:53 +0900
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Subject: [PATCH 16/18] Make "dev -d|-D" options parse sbitmap on Linux 4.18
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and later
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There have been a few reports that the "dev -d|-D" options displayed
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incorrect I/O stats due to racy blk_mq_ctx.rq_* counters. To fix it,
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make the options parse sbitmap to count I/O stats on Linux 4.18 and
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later kernels, which include RHEL8 ones.
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To do this, adjust to the blk_mq_tags structure of Linux 5.10 through
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5.15 kernels, which contain kernel commit 222a5ae03cdd ("blk-mq: Use
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pointers for blk_mq_tags bitmap tags") and do not contain ae0f1a732f4a
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("blk-mq: Stop using pointers for blk_mq_tags bitmap tags").
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Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
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Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
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---
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dev.c | 25 +++++++++++++++++++++++--
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1 file changed, 23 insertions(+), 2 deletions(-)
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diff --git a/dev.c b/dev.c
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index 0172c83ffaea..db97f8aebdc2 100644
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--- a/dev.c
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+++ b/dev.c
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@@ -4339,6 +4339,10 @@ static void bt_for_each(ulong q, ulong tags, ulong sbq, uint reserved, uint nr_r
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static void queue_for_each_hw_ctx(ulong q, ulong *hctx, uint cnt, struct diskio *dio)
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{
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uint i;
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+ int bitmap_tags_is_ptr = 0;
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+
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+ if (MEMBER_TYPE("blk_mq_tags", "bitmap_tags") == TYPE_CODE_PTR)
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+ bitmap_tags_is_ptr = 1;
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for (i = 0; i < cnt; i++) {
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ulong addr = 0, tags = 0;
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@@ -4357,9 +4361,17 @@ static void queue_for_each_hw_ctx(ulong q, ulong *hctx, uint cnt, struct diskio
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if (nr_reserved_tags) {
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addr = tags + OFFSET(blk_mq_tags_breserved_tags);
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+ if (bitmap_tags_is_ptr &&
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+ !readmem(addr, KVADDR, &addr, sizeof(ulong),
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+ "blk_mq_tags.bitmap_tags", RETURN_ON_ERROR))
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+ break;
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bt_for_each(q, tags, addr, 1, nr_reserved_tags, dio);
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}
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addr = tags + OFFSET(blk_mq_tags_bitmap_tags);
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+ if (bitmap_tags_is_ptr &&
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+ !readmem(addr, KVADDR, &addr, sizeof(ulong),
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+ "blk_mq_tags.bitmap_tags", RETURN_ON_ERROR))
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+ break;
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bt_for_each(q, tags, addr, 0, nr_reserved_tags, dio);
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}
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}
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@@ -4423,14 +4435,23 @@ get_mq_diskio(unsigned long q, unsigned long *mq_count)
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unsigned long mctx_addr;
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struct diskio tmp = {0};
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- if (INVALID_MEMBER(blk_mq_ctx_rq_dispatched) ||
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- INVALID_MEMBER(blk_mq_ctx_rq_completed)) {
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+ /*
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+ * Currently this function does not support old blk-mq implementation
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+ * before 12f5b9314545 ("blk-mq: Remove generation seqeunce"), so
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+ * filter them out.
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+ */
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+ if (VALID_MEMBER(request_state)) {
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+ if (CRASHDEBUG(1))
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+ fprintf(fp, "mq: using sbitmap\n");
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get_mq_diskio_from_hw_queues(q, &tmp);
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mq_count[0] = tmp.read;
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mq_count[1] = tmp.write;
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return;
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}
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+ if (CRASHDEBUG(1))
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+ fprintf(fp, "mq: using blk_mq_ctx.rq_{completed,dispatched} counters\n");
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+
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readmem(q + OFFSET(request_queue_queue_ctx), KVADDR, &queue_ctx,
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sizeof(ulong), "request_queue.queue_ctx",
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FAULT_ON_ERROR);
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--
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2.30.2
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