criu: lazy-pages: move find_vmas and related code around

Moving the find_vmas and collect_uffd_pages functions before they are
actually used. This allows to drop forward declaration of find_vmas and
will make subsequent refactoring cleaner.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/uffd.c

@@ -287,7 +287,160 @@ out:
 	return -1;
 }
 
-static int find_vmas(struct lazy_pages_info *lpi);
+#define UFFD_FLAG_SENT	0x1
+
+struct uffd_pages_struct {
+	struct list_head list;
+	unsigned long addr;
+	int flags;
+};
+
+static int collect_uffd_pages(struct page_read *pr, struct lazy_pages_info *lpi)
+{
+	unsigned long base;
+	int i;
+	struct iovec iov;
+	unsigned long nr_pages;
+	unsigned long ps;
+	int rc;
+	struct uffd_pages_struct *uffd_pages;
+	struct vma_area *vma;
+	struct vm_area_list *vmas;
+	struct pstree_item *item = pstree_item_by_virt(lpi->pid);
+
+	BUG_ON(!item);
+
+	vmas = &rsti(item)->vmas;
+
+	rc = pr->get_pagemap(pr, &iov);
+	if (rc <= 0)
+		return 0;
+
+	ps = page_size();
+	nr_pages = iov.iov_len / ps;
+	base = (unsigned long) iov.iov_base;
+	pr_debug("iov.iov_base 0x%lx (%ld pages)\n", base, nr_pages);
+
+	for (i = 0; i < nr_pages; i++) {
+		bool uffd_page = false;
+		base = (unsigned long) iov.iov_base + (i * ps);
+		/*
+		 * Only pages which are MAP_ANONYMOUS and MAP_PRIVATE
+		 * are relevant for userfaultfd handling.
+		 * Loop over all VMAs to see if the flags matching.
+		 */
+		list_for_each_entry(vma, &vmas->h, list) {
+			/*
+			 * This loop assumes that base can actually be found
+			 * in the VMA list.
+			 */
+			if (base >= vma->e->start && base < vma->e->end) {
+				if (vma_entry_can_be_lazy(vma->e)) {
+					if(!pagemap_in_parent(pr->pe))
+						uffd_page = true;
+					break;
+				}
+			}
+		}
+
+		/* This is not a page we are looking for. Move along */
+		if (!uffd_page)
+			continue;
+
+		pr_debug("Adding 0x%lx to our list\n", base);
+
+		uffd_pages = xzalloc(sizeof(struct uffd_pages_struct));
+		if (!uffd_pages)
+			return -1;
+		uffd_pages->addr = base;
+		list_add(&uffd_pages->list, &lpi->pages);
+	}
+
+	return 1;
+}
+
+/*
+ *  Setting up criu infrastructure and scan for VMAs.
+ */
+static int find_vmas(struct lazy_pages_info *lpi)
+{
+	struct cr_img *img;
+	int ret;
+	struct vm_area_list vmas;
+	int vn = 0;
+	struct rst_info *ri;
+	struct uffd_pages_struct *uffd_pages;
+	struct pstree_item *item = pstree_item_by_virt(lpi->pid);
+
+	BUG_ON(!item);
+
+	vm_area_list_init(&vmas);
+
+	ri = rsti(item);
+	if (!ri)
+		return -1;
+
+	img = open_image(CR_FD_MM, O_RSTR, lpi->pid);
+	if (!img)
+		return -1;
+
+	ret = pb_read_one_eof(img, &ri->mm, PB_MM);
+	close_image(img);
+	if (ret == -1)
+		return -1;
+
+	pr_debug("Found %zd VMAs in image\n", ri->mm->n_vmas);
+
+	while (vn < ri->mm->n_vmas) {
+		struct vma_area *vma;
+
+		ret = -1;
+		vma = alloc_vma_area();
+		if (!vma)
+			goto out;
+
+		ret = 0;
+		ri->vmas.nr++;
+		vma->e = ri->mm->vmas[vn++];
+
+		list_add_tail(&vma->list, &ri->vmas.h);
+
+		if (vma_area_is_private(vma, kdat.task_size)) {
+			vmas.priv_size += vma_area_len(vma);
+			if (vma->e->flags & MAP_GROWSDOWN)
+				vmas.priv_size += PAGE_SIZE;
+		}
+
+		pr_info("vma 0x%"PRIx64" 0x%"PRIx64"\n", vma->e->start, vma->e->end);
+	}
+
+	ret = open_page_read(lpi->pid, &lpi->pr, PR_TASK);
+	if (ret <= 0) {
+		ret = -1;
+		goto out;
+	}
+	/*
+	 * This puts all pages which should be handled by userfaultfd
+	 * in the list uffd_list. This list is later used to detect if
+	 * a page has already been transferred or if it needs to be
+	 * pushed into the process using userfaultfd.
+	 */
+	do {
+		ret = collect_uffd_pages(&lpi->pr, lpi);
+		if (ret == -1) {
+			goto out;
+		}
+	} while (ret);
+
+	/* Count detected pages */
+	list_for_each_entry(uffd_pages, &lpi->pages, list)
+	    ret++;
+
+	pr_debug("Found %d pages to be handled by UFFD\n", ret);
+
+out:
+	return ret;
+}
 
 static int ud_open(int client, struct lazy_pages_info **_lpi)
 {
@@ -366,14 +519,6 @@ static int get_page(struct lazy_pages_info *lpi, unsigned long addr, void *dest)
 	return 1;
 }
 
-#define UFFD_FLAG_SENT	0x1
-
-struct uffd_pages_struct {
-	struct list_head list;
-	unsigned long addr;
-	int flags;
-};
-
 static int uffd_copy_page(struct lazy_pages_info *lpi, __u64 address,
 			  void *dest)
 {
@@ -448,70 +593,6 @@ static int uffd_handle_page(struct lazy_pages_info *lpi, __u64 address,
 	return rc;
 }
 
-static int collect_uffd_pages(struct page_read *pr, struct lazy_pages_info *lpi)
-{
-	unsigned long base;
-	int i;
-	struct iovec iov;
-	unsigned long nr_pages;
-	unsigned long ps;
-	int rc;
-	struct uffd_pages_struct *uffd_pages;
-	struct vma_area *vma;
-	struct vm_area_list *vmas;
-	struct pstree_item *item = pstree_item_by_virt(lpi->pid);
-
-	BUG_ON(!item);
-
-	vmas = &rsti(item)->vmas;
-
-	rc = pr->get_pagemap(pr, &iov);
-	if (rc <= 0)
-		return 0;
-
-	ps = page_size();
-	nr_pages = iov.iov_len / ps;
-	base = (unsigned long) iov.iov_base;
-	pr_debug("iov.iov_base 0x%lx (%ld pages)\n", base, nr_pages);
-
-	for (i = 0; i < nr_pages; i++) {
-		bool uffd_page = false;
-		base = (unsigned long) iov.iov_base + (i * ps);
-		/*
-		 * Only pages which are MAP_ANONYMOUS and MAP_PRIVATE
-		 * are relevant for userfaultfd handling.
-		 * Loop over all VMAs to see if the flags matching.
-		 */
-		list_for_each_entry(vma, &vmas->h, list) {
-			/*
-			 * This loop assumes that base can actually be found
-			 * in the VMA list.
-			 */
-			if (base >= vma->e->start && base < vma->e->end) {
-				if (vma_entry_can_be_lazy(vma->e)) {
-					if(!pagemap_in_parent(pr->pe))
-						uffd_page = true;
-					break;
-				}
-			}
-		}
-
-		/* This is not a page we are looking for. Move along */
-		if (!uffd_page)
-			continue;
-
-		pr_debug("Adding 0x%lx to our list\n", base);
-
-		uffd_pages = xzalloc(sizeof(struct uffd_pages_struct));
-		if (!uffd_pages)
-			return -1;
-		uffd_pages->addr = base;
-		list_add(&uffd_pages->list, &lpi->pages);
-	}
-
-	return 1;
-}
-
 static int handle_remaining_pages(struct lazy_pages_info *lpi, void *dest)
 {
 	struct uffd_pages_struct *uffd_pages;
@@ -560,89 +641,6 @@ static int handle_regular_pages(struct lazy_pages_info *lpi, void *dest,
 	return 0;
 }
 
-/*
- *  Setting up criu infrastructure and scan for VMAs.
- */
-static int find_vmas(struct lazy_pages_info *lpi)
-{
-	struct cr_img *img;
-	int ret;
-	struct vm_area_list vmas;
-	int vn = 0;
-	struct rst_info *ri;
-	struct uffd_pages_struct *uffd_pages;
-	struct pstree_item *item = pstree_item_by_virt(lpi->pid);
-
-	BUG_ON(!item);
-
-	vm_area_list_init(&vmas);
-
-	ri = rsti(item);
-	if (!ri)
-		return -1;
-
-	img = open_image(CR_FD_MM, O_RSTR, lpi->pid);
-	if (!img)
-		return -1;
-
-	ret = pb_read_one_eof(img, &ri->mm, PB_MM);
-	close_image(img);
-	if (ret == -1)
-		return -1;
-
-	pr_debug("Found %zd VMAs in image\n", ri->mm->n_vmas);
-
-	while (vn < ri->mm->n_vmas) {
-		struct vma_area *vma;
-
-		ret = -1;
-		vma = alloc_vma_area();
-		if (!vma)
-			goto out;
-
-		ret = 0;
-		ri->vmas.nr++;
-		vma->e = ri->mm->vmas[vn++];
-
-		list_add_tail(&vma->list, &ri->vmas.h);
-
-		if (vma_area_is_private(vma, kdat.task_size)) {
-			vmas.priv_size += vma_area_len(vma);
-			if (vma->e->flags & MAP_GROWSDOWN)
-				vmas.priv_size += PAGE_SIZE;
-		}
-
-		pr_info("vma 0x%"PRIx64" 0x%"PRIx64"\n", vma->e->start, vma->e->end);
-	}
-
-	ret = open_page_read(lpi->pid, &lpi->pr, PR_TASK);
-	if (ret <= 0) {
-		ret = -1;
-		goto out;
-	}
-	/*
-	 * This puts all pages which should be handled by userfaultfd
-	 * in the list uffd_list. This list is later used to detect if
-	 * a page has already been transferred or if it needs to be
-	 * pushed into the process using userfaultfd.
-	 */
-	do {
-		ret = collect_uffd_pages(&lpi->pr, lpi);
-		if (ret == -1) {
-			goto out;
-		}
-	} while (ret);
-
-	/* Count detected pages */
-	list_for_each_entry(uffd_pages, &lpi->pages, list)
-	    ret++;
-
-	pr_debug("Found %d pages to be handled by UFFD\n", ret);
-
-out:
-	return ret;
-}
-
 static int handle_user_fault(struct lazy_pages_info *lpi, void *dest)
 {
 	struct uffd_msg msg;