crash/0009-Fix-for-dev-d-D-options-to-support-blk-mq-change-on-.patch

From 7b91ac6d20b741c1c8487a04d2b9d8aee5772471 Mon Sep 17 00:00:00 2001
From: Lianbo Jiang <lijiang@redhat.com>
Date: Thu, 2 Jun 2022 20:12:56 +0800
Subject: [PATCH 09/89] Fix for "dev -d|-D" options to support blk-mq change on
 Linux v5.18-rc1

Kernel commit 4e5cc99e1e48 ("blk-mq: manage hctx map via xarray") removed
the "queue_hw_ctx" member from struct request_queue at Linux v5.18-rc1,
and replaced it with a struct xarray "hctx_table". Without the patch, the
"dev -d|-D" options will print an error:

  crash> dev -d
  MAJOR GENDISK            NAME       REQUEST_QUEUE      TOTAL  READ WRITE

  dev: invalid structure member offset: request_queue_queue_hw_ctx

With the patch:
  crash> dev -d
  MAJOR GENDISK            NAME       REQUEST_QUEUE      TOTAL  READ WRITE
      8 ffff8e99d0a1ae00   sda        ffff8e9c14c59980      10     6     4

Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
---
 defs.h    |  1 +
 dev.c     | 42 +++++++++++++++++++++++++++++++++---------
 symbols.c |  2 ++
 3 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/defs.h b/defs.h
index f2b6ab14c6aa..c524a05d8105 100644
--- a/defs.h
+++ b/defs.h
@@ -2180,6 +2180,7 @@ struct offset_table {                    /* stash of commonly-used offsets */
 	long blk_mq_tags_breserved_tags;
 	long blk_mq_tags_nr_reserved_tags;
 	long blk_mq_tags_rqs;
+	long request_queue_hctx_table;
 };
 
 struct size_table {         /* stash of commonly-used sizes */
diff --git a/dev.c b/dev.c
index 4be4c96df8b0..0172c83ffaea 100644
--- a/dev.c
+++ b/dev.c
@@ -4369,20 +4369,42 @@ static void get_mq_diskio_from_hw_queues(ulong q, struct diskio *dio)
 	uint cnt = 0;
 	ulong addr = 0, hctx_addr = 0;
 	ulong *hctx_array = NULL;
+	struct list_pair *lp = NULL;
+
+	if (VALID_MEMBER(request_queue_hctx_table)) {
+		addr = q + OFFSET(request_queue_hctx_table);
+		cnt = do_xarray(addr, XARRAY_COUNT, NULL);
+		lp = (struct list_pair *)GETBUF(sizeof(struct list_pair) * (cnt + 1));
+		if (!lp)
+			error(FATAL, "fail to get memory for list_pair.\n");
+		lp[0].index = cnt;
+		cnt = do_xarray(addr, XARRAY_GATHER, lp);
+	} else {
+		addr = q + OFFSET(request_queue_nr_hw_queues);
+		readmem(addr, KVADDR, &cnt, sizeof(uint),
+			"request_queue.nr_hw_queues", FAULT_ON_ERROR);
 
-	addr = q + OFFSET(request_queue_nr_hw_queues);
-	readmem(addr, KVADDR, &cnt, sizeof(uint),
-		"request_queue.nr_hw_queues", FAULT_ON_ERROR);
-
-	addr = q + OFFSET(request_queue_queue_hw_ctx);
-	readmem(addr, KVADDR, &hctx_addr, sizeof(void *),
-		"request_queue.queue_hw_ctx", FAULT_ON_ERROR);
+		addr = q + OFFSET(request_queue_queue_hw_ctx);
+		readmem(addr, KVADDR, &hctx_addr, sizeof(void *),
+			"request_queue.queue_hw_ctx", FAULT_ON_ERROR);
+	}
 
 	hctx_array = (ulong *)GETBUF(sizeof(void *) * cnt);
-	if (!hctx_array)
+	if (!hctx_array) {
+		if (lp)
+			FREEBUF(lp);
 		error(FATAL, "fail to get memory for the hctx_array\n");
+	}
+
+	if (lp && hctx_array) {
+		uint i;
+
+		/* copy it from list_pair to hctx_array */
+		for (i = 0; i < cnt; i++)
+			hctx_array[i] = (ulong)lp[i].value;
 
-	if (!readmem(hctx_addr, KVADDR, hctx_array, sizeof(void *) * cnt,
+		FREEBUF(lp);
+	} else if (!readmem(hctx_addr, KVADDR, hctx_array, sizeof(void *) * cnt,
 			"request_queue.queue_hw_ctx[]", RETURN_ON_ERROR)) {
 		FREEBUF(hctx_array);
 		return;
@@ -4755,6 +4777,8 @@ void diskio_init(void)
 			"request_queue", "queue_hw_ctx");
 		MEMBER_OFFSET_INIT(request_queue_nr_hw_queues,
 			"request_queue", "nr_hw_queues");
+		MEMBER_OFFSET_INIT(request_queue_hctx_table,
+			"request_queue", "hctx_table");
 		MEMBER_OFFSET_INIT(blk_mq_ctx_rq_dispatched, "blk_mq_ctx",
 			"rq_dispatched");
 		MEMBER_OFFSET_INIT(blk_mq_ctx_rq_completed, "blk_mq_ctx",
diff --git a/symbols.c b/symbols.c
index 520debdb311e..69004a2e66e3 100644
--- a/symbols.c
+++ b/symbols.c
@@ -10415,6 +10415,8 @@ dump_offset_table(char *spec, ulong makestruct)
 		OFFSET(request_queue_queue_hw_ctx));
 	fprintf(fp, "    request_queue_nr_hw_queues: %ld\n",
 		OFFSET(request_queue_nr_hw_queues));
+	fprintf(fp, "      request_queue_hctx_table: %ld\n",
+		OFFSET(request_queue_hctx_table));
 	fprintf(fp, "      blk_mq_ctx_rq_dispatched: %ld\n",
 		OFFSET(blk_mq_ctx_rq_dispatched));
 	fprintf(fp, "       blk_mq_ctx_rq_completed: %ld\n",
-- 
2.37.1