page_read: Make it possible to get pages.img ID from page_read

The pages.img will need to get opened one more time w/o the pagemap.img.
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/image.c

@@ -461,29 +461,27 @@ void up_page_ids_base(void)
 	page_ids += 0x10000;
 }
 
-struct cr_img *open_pages_image_at(int dfd, unsigned long flags, struct cr_img *pmi)
+struct cr_img *open_pages_image_at(int dfd, unsigned long flags, struct cr_img *pmi, u32 *id)
 {
-	unsigned id;
-
 	if (flags == O_RDONLY || flags == O_RDWR) {
 		PagemapHead *h;
 		if (pb_read_one(pmi, &h, PB_PAGEMAP_HEAD) < 0)
 			return NULL;
-		id = h->pages_id;
+		*id = h->pages_id;
 		pagemap_head__free_unpacked(h, NULL);
 	} else {
 		PagemapHead h = PAGEMAP_HEAD__INIT;
-		id = h.pages_id = page_ids++;
+		*id = h.pages_id = page_ids++;
 		if (pb_write_one(pmi, &h, PB_PAGEMAP_HEAD) < 0)
 			return NULL;
 	}
 
-	return open_image_at(dfd, CR_FD_PAGES, flags, id);
+	return open_image_at(dfd, CR_FD_PAGES, flags, *id);
 }
 
-struct cr_img *open_pages_image(unsigned long flags, struct cr_img *pmi)
+struct cr_img *open_pages_image(unsigned long flags, struct cr_img *pmi, u32 *id)
 {
-	return open_pages_image_at(get_service_fd(IMG_FD_OFF), flags, pmi);
+	return open_pages_image_at(get_service_fd(IMG_FD_OFF), flags, pmi, id);
 }
 
 /*

criu/include/image.h

@@ -150,8 +150,8 @@ extern void close_image_dir(void);
 extern struct cr_img *open_image_at(int dfd, int type, unsigned long flags, ...);
 #define open_image(typ, flags, ...) open_image_at(-1, typ, flags, ##__VA_ARGS__)
 extern int open_image_lazy(struct cr_img *img);
-extern struct cr_img *open_pages_image(unsigned long flags, struct cr_img *pmi);
-extern struct cr_img *open_pages_image_at(int dfd, unsigned long flags, struct cr_img *pmi);
+extern struct cr_img *open_pages_image(unsigned long flags, struct cr_img *pmi, u32 *pages_id);
+extern struct cr_img *open_pages_image_at(int dfd, unsigned long flags, struct cr_img *pmi, u32 *pages_id);
 extern void up_page_ids_base(void);
 
 extern struct cr_img *img_from_fd(int fd); /* for cr-show mostly */

criu/include/pagemap.h

@@ -55,6 +55,7 @@ struct page_read {
 	/* Private data of reader */
 	struct cr_img *pmi;
 	struct cr_img *pi;
+	u32 pages_img_id;
 
 	PagemapEntry *pe;		/* current pagemap we are on */
 	struct page_read *parent;	/* parent pagemap (if ->in_parent

criu/page-xfer.c

@@ -267,11 +267,13 @@ static void close_page_xfer(struct page_xfer *xfer)
 
 static int open_page_local_xfer(struct page_xfer *xfer, int fd_type, long id)
 {
+	u32 pages_id;
+
 	xfer->pmi = open_image(fd_type, O_DUMP, id);
 	if (!xfer->pmi)
 		return -1;
 
-	xfer->pi = open_pages_image(O_DUMP, xfer->pmi);
+	xfer->pi = open_pages_image(O_DUMP, xfer->pmi, &pages_id);
 	if (!xfer->pi) {
 		close_image(xfer->pmi);
 		return -1;

criu/pagemap.c

@@ -655,7 +655,7 @@ int open_page_read_at(int dfd, int pid, struct page_read *pr, int pr_flags)
 		return -1;
 	}
 
-	pr->pi = open_pages_image_at(dfd, flags, pr->pmi);
+	pr->pi = open_pages_image_at(dfd, flags, pr->pmi, &pr->pages_img_id);
 	if (!pr->pi) {
 		close_page_read(pr);
 		return -1;