criu: page-pipe: add ability to allocate IOVs

When collection of dumpee pages is followed by any parasite operation, we
cannot share iovs between parasite args area and page-pipe.
As a bonus we get some simplification of dump_one_shmem.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/include/page-pipe.h

@@ -93,6 +93,7 @@ struct page_pipe {
 
 	bool chunk_mode;	/* Restrict the maximum buffer size of pipes
 				   and dump memory for a few iterations */
+	bool own_iovs;		/* create_page_pipe allocated IOVs memory */
 };
 
 extern struct page_pipe *create_page_pipe(unsigned int nr,

criu/page-pipe.c

@@ -111,26 +111,41 @@ struct page_pipe *create_page_pipe(unsigned int nr_segs,
 
 	pr_debug("Create page pipe for %u segs\n", nr_segs);
 
-	pp = xmalloc(sizeof(*pp));
-	if (pp) {
-		pp->nr_pipes = 0;
-		INIT_LIST_HEAD(&pp->bufs);
-		INIT_LIST_HEAD(&pp->free_bufs);
-		pp->nr_iovs = nr_segs;
-		pp->iovs = iovs;
-		pp->free_iov = 0;
-
-		pp->nr_holes = 0;
-		pp->free_hole = 0;
-		pp->holes = NULL;
-
-		pp->chunk_mode = chunk_mode;
-
-		if (page_pipe_grow(pp))
-			return NULL;
+	pp = xzalloc(sizeof(*pp));
+	if (!pp)
+		return NULL;
+
+	if (!iovs) {
+		iovs = xmalloc(sizeof(*iovs) * nr_segs);
+		if (!iovs)
+			goto err_free_pp;
+		pp->own_iovs = true;
 	}
 
+	pp->nr_pipes = 0;
+	INIT_LIST_HEAD(&pp->bufs);
+	INIT_LIST_HEAD(&pp->free_bufs);
+	pp->nr_iovs = nr_segs;
+	pp->iovs = iovs;
+	pp->free_iov = 0;
+
+	pp->nr_holes = 0;
+	pp->free_hole = 0;
+	pp->holes = NULL;
+
+	pp->chunk_mode = chunk_mode;
+
+	if (page_pipe_grow(pp))
+		goto err_free_iovs;
+
 	return pp;
+
+err_free_iovs:
+	if (pp->own_iovs)
+		xfree(iovs);
+err_free_pp:
+	xfree(pp);
+	return NULL;
 }
 
 void destroy_page_pipe(struct page_pipe *pp)
@@ -143,6 +158,8 @@ void destroy_page_pipe(struct page_pipe *pp)
 	list_for_each_entry_safe(ppb, n, &pp->bufs, l)
 		ppb_destroy(ppb);
 
+	if (pp->own_iovs)
+		xfree(pp->iovs);
 	xfree(pp);
 }
 

criu/shmem.c

@@ -527,7 +527,6 @@ static int dump_pages(struct page_pipe *pp, struct page_xfer *xfer, void *addr)
 
 static int dump_one_shmem(struct shmem_info *si)
 {
-	struct iovec *iovs;
 	struct page_pipe *pp;
 	struct page_xfer xfer;
 	int err, ret = -1, fd;
@@ -565,13 +564,9 @@ static int dump_one_shmem(struct shmem_info *si)
 	if (err)
 		goto err_unmap;
 
-	iovs = xmalloc(((nrpages + 1) / 2) * sizeof(struct iovec));
-	if (!iovs)
-		goto err_unmap;
-
-	pp = create_page_pipe((nrpages + 1) / 2, iovs, true);
+	pp = create_page_pipe((nrpages + 1) / 2, NULL, true);
 	if (!pp)
-		goto err_iovs;
+		goto err_unmap;
 
 	err = open_page_xfer(&xfer, CR_FD_SHMEM_PAGEMAP, si->shmid);
 	if (err)
@@ -598,8 +593,6 @@ err_xfer:
 	xfer.close(&xfer);
 err_pp:
 	destroy_page_pipe(pp);
-err_iovs:
-	xfree(iovs);
 err_unmap:
 	munmap(addr,  si->size);
 err: