page-read: Add async arg to ->read_pages callback

Flag PR_ASYNC means, that the caller is OK if the routine
returns w/o data read into the buffer provided.

https://travis-ci.org/criupatchwork/criu/builds/175451746Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/include/pagemap.h

@@ -47,7 +47,8 @@ struct page_read {
 	 */
 	int (*get_pagemap)(struct page_read *, struct iovec *iov);
 	/* reads page from current pagemap */
-	int (*read_pages)(struct page_read *, unsigned long vaddr, int nr, void *);
+	int (*read_pages)(struct page_read *, unsigned long vaddr, int nr,
+			  void *, unsigned flags);
 	void (*close)(struct page_read *);
 	int (*seek_page)(struct page_read *pr, unsigned long vaddr, bool warn);
 
@@ -72,6 +73,10 @@ struct page_read {
 	int curr_pme;
 };
 
+/* flags for ->read_pages */
+#define PR_ASYNC	0x1 /* may exit w/o data in the buffer */
+
+/* flags for open_page_read */
 #define PR_SHMEM	0x1
 #define PR_TASK		0x2
 

criu/mem.c

@@ -748,7 +748,7 @@ static int restore_priv_vma_content(struct pstree_item *t)
 			if (vma->ppage_bitmap) { /* inherited vma */
 				clear_bit(off, vma->ppage_bitmap);
 
-				ret = pr.read_pages(&pr, va, 1, buf);
+				ret = pr.read_pages(&pr, va, 1, buf, 0);
 				if (ret < 0)
 					goto err_read;
 
@@ -776,7 +776,7 @@ static int restore_priv_vma_content(struct pstree_item *t)
 
 				nr = min_t(int, nr_pages - i, (vma->e->end - va) / PAGE_SIZE);
 
-				ret = pr.read_pages(&pr, va, nr, p);
+				ret = pr.read_pages(&pr, va, nr, p, PR_ASYNC);
 				if (ret < 0)
 					goto err_read;
 

criu/pagemap.c

@@ -204,7 +204,7 @@ static inline void pagemap_bound_check(PagemapEntry *pe, unsigned long vaddr, in
 }
 
 static int read_parent_page(struct page_read *pr, unsigned long vaddr,
-			    int nr, void *buf)
+			    int nr, void *buf, unsigned flags)
 {
 	struct page_read *ppr = pr->parent;
 	int ret;
@@ -235,7 +235,7 @@ static int read_parent_page(struct page_read *pr, unsigned long vaddr,
 		if (p_nr > nr)
 			p_nr = nr;
 
-		ret = ppr->read_pages(ppr, vaddr, p_nr, buf);
+		ret = ppr->read_pages(ppr, vaddr, p_nr, buf, flags);
 		if (ret == -1)
 			return ret;
 
@@ -253,7 +253,7 @@ static int read_parent_page(struct page_read *pr, unsigned long vaddr,
 }
 
 static int read_local_page(struct page_read *pr, unsigned long vaddr,
-			   unsigned long len, void *buf)
+			   unsigned long len, void *buf, unsigned flags)
 {
 	int fd = img_raw_fd(pr->pi);
 	int ret;
@@ -277,7 +277,8 @@ static int read_local_page(struct page_read *pr, unsigned long vaddr,
 	return 0;
 }
 
-static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, int nr, void *buf)
+static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, int nr,
+			     void *buf, unsigned flags)
 {
 	unsigned long len = nr * PAGE_SIZE;
 
@@ -285,10 +286,10 @@ static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, int nr,
 	pagemap_bound_check(pr->pe, vaddr, nr);
 
 	if (pr->pe->in_parent) {
-		if (read_parent_page(pr, vaddr, nr, buf) < 0)
+		if (read_parent_page(pr, vaddr, nr, buf, flags) < 0)
 			return -1;
 	} else {
-		if (read_local_page(pr, vaddr, len, buf) < 0)
+		if (read_local_page(pr, vaddr, len, buf, flags) < 0)
 			return -1;
 	}
 

criu/shmem.c

@@ -480,7 +480,7 @@ static int restore_shmem_content(void *addr, struct shmem_info *si)
 		if (vaddr + nr_pages * PAGE_SIZE > si->size)
 			break;
 
-		pr.read_pages(&pr, vaddr, nr_pages, addr + vaddr);
+		pr.read_pages(&pr, vaddr, nr_pages, addr + vaddr, 0);
 	}
 
 	pr.close(&pr);