[PATCH v2] makedumpfile: support _count -> _refcount rename in struct page

[Atsushi Kumagai]

Hello Vitaly,

>_count member was renamed to _refcount in linux commit 0139aa7b7fa12
>("mm: rename _count, field of the struct page, to _refcount") and this
>broke makedumpfile. The reason for making the change was to find all users
>accessing it directly and not through the recommended API. I tried
>suggesting to revert the change but failed, I see no other choice than to
>start supporting both _count and _refcount in makedumpfile.
>
>Signed-off-by: Vitaly Kuznetsov <vkuznets at redhat.com>
>---
>Changes since 'v1':
>- Make '_refcount' the default [Atsushi Kumagai]

Good fix, I'll merge this into v1.6.1.

Thanks,
Atsushi Kumagai

>---
> makedumpfile.c | 26 +++++++++++++++++++++-----
> makedumpfile.h |  3 ++-
> 2 files changed, 23 insertions(+), 6 deletions(-)
>
>diff --git a/makedumpfile.c b/makedumpfile.c
>index 853b999..fd884d3 100644
>--- a/makedumpfile.c
>+++ b/makedumpfile.c
>@@ -1579,7 +1579,14 @@ get_structure_info(void)
> 	 */
> 	SIZE_INIT(page, "page");
> 	OFFSET_INIT(page.flags, "page", "flags");
>-	OFFSET_INIT(page._count, "page", "_count");
>+	OFFSET_INIT(page._refcount, "page", "_refcount");
>+	if (OFFSET(page._refcount) == NOT_FOUND_STRUCTURE) {
>+		info->flag_use_count = TRUE;
>+		OFFSET_INIT(page._refcount, "page", "_count");
>+	} else {
>+		info->flag_use_count = FALSE;
>+	}
>+
> 	OFFSET_INIT(page.mapping, "page", "mapping");
> 	OFFSET_INIT(page._mapcount, "page", "_mapcount");
> 	OFFSET_INIT(page.private, "page", "private");
>@@ -2044,7 +2051,7 @@ get_mem_type(void)
>
> 	if ((SIZE(page) == NOT_FOUND_STRUCTURE)
> 	    || (OFFSET(page.flags) == NOT_FOUND_STRUCTURE)
>-	    || (OFFSET(page._count) == NOT_FOUND_STRUCTURE)
>+	    || (OFFSET(page._refcount) == NOT_FOUND_STRUCTURE)
> 	    || (OFFSET(page.mapping) == NOT_FOUND_STRUCTURE)) {
> 		ret = NOT_FOUND_MEMTYPE;
> 	} else if ((((SYMBOL(node_data) != NOT_FOUND_SYMBOL)
>@@ -2151,7 +2158,10 @@ write_vmcoreinfo_data(void)
> 	 * write the member offset of 1st kernel
> 	 */
> 	WRITE_MEMBER_OFFSET("page.flags", page.flags);
>-	WRITE_MEMBER_OFFSET("page._count", page._count);
>+	if (info->flag_use_count)
>+		WRITE_MEMBER_OFFSET("page._count", page._refcount);
>+	else
>+		WRITE_MEMBER_OFFSET("page._refcount", page._refcount);
> 	WRITE_MEMBER_OFFSET("page.mapping", page.mapping);
> 	WRITE_MEMBER_OFFSET("page.lru", page.lru);
> 	WRITE_MEMBER_OFFSET("page._mapcount", page._mapcount);
>@@ -2491,7 +2501,13 @@ read_vmcoreinfo(void)
>
>
> 	READ_MEMBER_OFFSET("page.flags", page.flags);
>-	READ_MEMBER_OFFSET("page._count", page._count);
>+	READ_MEMBER_OFFSET("page._refcount", page._refcount);
>+	if (OFFSET(page._refcount) == NOT_FOUND_STRUCTURE) {
>+		info->flag_use_count = TRUE;
>+		READ_MEMBER_OFFSET("page._count", page._refcount);
>+	} else {
>+		info->flag_use_count = FALSE;
>+	}
> 	READ_MEMBER_OFFSET("page.mapping", page.mapping);
> 	READ_MEMBER_OFFSET("page.lru", page.lru);
> 	READ_MEMBER_OFFSET("page._mapcount", page._mapcount);
>@@ -5615,7 +5631,7 @@ __exclude_unnecessary_pages(unsigned long mem_map,
> 		pcache  = page_cache + (index_pg * SIZE(page));
>
> 		flags   = ULONG(pcache + OFFSET(page.flags));
>-		_count  = UINT(pcache + OFFSET(page._count));
>+		_count  = UINT(pcache + OFFSET(page._refcount));
> 		mapping = ULONG(pcache + OFFSET(page.mapping));
>
> 		if (OFFSET(page.compound_order) != NOT_FOUND_STRUCTURE) {
>diff --git a/makedumpfile.h b/makedumpfile.h
>index 251d4bf..533e5b8 100644
>--- a/makedumpfile.h
>+++ b/makedumpfile.h
>@@ -1100,6 +1100,7 @@ struct DumpInfo {
> 	int		flag_nospace;	     /* the flag of "No space on device" error */
> 	int		flag_vmemmap;        /* kernel supports vmemmap address space */
> 	int		flag_excludevm;      /* -e - excluding unused vmemmap pages */
>+	int		flag_use_count;      /* _refcount is named _count in struct page */
> 	unsigned long	vaddr_for_vtop;      /* virtual address for debugging */
> 	long		page_size;           /* size of page */
> 	long		page_shift;
>@@ -1483,7 +1484,7 @@ struct size_table {
> struct offset_table {
> 	struct page {
> 		long	flags;
>-		long	_count;
>+		long	_refcount;
> 		long	mapping;
> 		long	lru;
> 		long	_mapcount;
>--
>2.5.5