criu: pagemap: replace 'zero' and 'lazy' booleans with 'flags'

Having three booleans in pagemap entry clues for usage of good old flags.
Replace 'zero' and 'lazy' booleans with flags and use flags for internal
tracking of in_parent value. Eventually, in_parent may be deprecated.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/cr-dedup.c

@@ -89,7 +89,7 @@ static int cr_dedup_one_pagemap(int id, int flags)
 
 		pr_debug("dedup iovec base=%"PRIx64", len=%lu\n",
 			 pr.pe->vaddr, pagemap_len(pr.pe));
-		if (!pr.pe->in_parent) {
+		if (!pagemap_in_parent(pr.pe)) {
 			ret = dedup_one_iovec(prp, pr.pe->vaddr,
 					      pagemap_len(pr.pe));
 			if (ret)

criu/include/pagemap.h

@@ -113,4 +113,25 @@ static inline unsigned long pagemap_len(PagemapEntry *pe)
 {
 	return pe->nr_pages * PAGE_SIZE;
 }
+
+/* Pagemap flags */
+#define PE_PARENT	(1 << 0)	/* pages are in parent snapshot */
+#define PE_ZERO		(1 << 1)	/* pages can be lazily restored */
+#define PE_LAZY		(1 << 2)	/* pages are mapped to zero pfn */
+
+static inline bool pagemap_in_parent(PagemapEntry *pe)
+{
+	return !!(pe->flags & PE_PARENT);
+}
+
+static inline bool pagemap_zero(PagemapEntry *pe)
+{
+	return !!(pe->flags & PE_ZERO);
+}
+
+static inline bool pagemap_lazy(PagemapEntry *pe)
+{
+	return !!(pe->flags & PE_LAZY);
+}
+
 #endif /* __CR_PAGE_READ_H__ */

criu/page-xfer.c

@@ -205,6 +205,7 @@ static int write_pagemap_loc(struct page_xfer *xfer,
 
 	pe.vaddr = encode_pointer(iov->iov_base);
 	pe.nr_pages = iov->iov_len / PAGE_SIZE;
+	pe.has_flags = true;
 	if (opts.auto_dedup && xfer->parent != NULL) {
 		ret = dedup_one_iovec(xfer->parent, pe.vaddr,
 				pagemap_len(&pe));
@@ -288,6 +289,7 @@ static int write_hole_loc(struct page_xfer *xfer, struct iovec *iov, int type)
 
 	pe.vaddr = encode_pointer(iov->iov_base);
 	pe.nr_pages = iov->iov_len / PAGE_SIZE;
+	pe.has_flags = true;
 
 	switch (type) {
 	case PS_IOV_HOLE:
@@ -301,17 +303,13 @@ static int write_hole_loc(struct page_xfer *xfer, struct iovec *iov, int type)
 				return -1;
 			}
 		}
-
-		pe.has_in_parent = true;
-		pe.in_parent = true;
+		pe.flags |= PE_PARENT;
 		break;
 	case PS_IOV_ZERO:
-		pe.has_zero = true;
-		pe.zero = true;
+		pe.flags |= PE_ZERO;
 		break;
 	case PS_IOV_LAZY:
-		pe.has_lazy = true;
-		pe.lazy = true;
+		pe.flags |= PE_LAZY;
 		break;
 	default:
 		return -1;

criu/pagemap.c

@@ -96,7 +96,7 @@ int dedup_one_iovec(struct page_read *pr, unsigned long off, unsigned long len)
 		if (!pr->pe)
 			return -1;
 		piov_end = pr->pe->vaddr + pagemap_len(pr->pe);
-		if (!pr->pe->in_parent) {
+		if (!pagemap_in_parent(pr->pe)) {
 			ret = punch_hole(pr, pr->pi_off, min(piov_end, iov_end) - off, false);
 			if (ret == -1)
 				return ret;
@@ -130,7 +130,7 @@ static int advance(struct page_read *pr)
 
 		pe = pr->pmes[pr->curr_pme];
 
-		if (!pe->zero)
+		if (!pagemap_zero(pe))
 			break;
 	}
 
@@ -144,7 +144,7 @@ static void skip_pagemap_pages(struct page_read *pr, unsigned long len)
 	if (!len)
 		return;
 
-	if (!pr->pe->in_parent && !pr->pe->zero && !pr->pe->lazy)
+	if (!pagemap_in_parent(pr->pe) && !pagemap_zero(pr->pe) && !pagemap_lazy(pr->pe))
 		pr->pi_off += len;
 	pr->cvaddr += len;
 }
@@ -415,10 +415,10 @@ static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, int nr,
 	pr_info("pr%u Read %lx %u pages\n", pr->id, vaddr, nr);
 	pagemap_bound_check(pr->pe, vaddr, nr);
 
-	if (pr->pe->in_parent) {
+	if (pagemap_in_parent(pr->pe)) {
 		if (read_parent_page(pr, vaddr, nr, buf, flags) < 0)
 			return -1;
-	} else if (pr->pe->zero) {
+	} else if (pagemap_zero(pr->pe)) {
 		/* zero mappings should be skipped by get_pagemap */
 		BUG();
 	} else {
@@ -603,6 +603,12 @@ err_cl:
 	return -1;
 }
 
+static void init_compat_pagemap_entry(PagemapEntry *pe)
+{
+	if (pe->has_in_parent && pe->in_parent)
+		pe->flags |= PE_PARENT;
+}
+
 /*
  * The pagemap entry size is at least 8 bytes for small mappings with
  * low address and may get to 18 bytes or even more for large mappings
@@ -638,6 +644,8 @@ static int init_pagemaps(struct page_read *pr)
 		if (ret == 0)
 			break;
 
+		init_compat_pagemap_entry(pr->pmes[pr->nr_pmes]);
+
 		pr->nr_pmes++;
 		if (pr->nr_pmes >= nr_pmes) {
 			nr_pmes += nr_realloc;

criu/uffd.c

@@ -371,7 +371,7 @@ static int get_page(struct lazy_pages_info *lpi, unsigned long addr, void *dest)
 	if (ret <= 0)
 		return ret;
 
-	if (lpi->pr.pe->zero)
+	if (pagemap_zero(lpi->pr.pe))
 		return 0;
 
 	ret = lpi->pr.read_pages(&lpi->pr, addr, 1, buf, 0);

images/pagemap.proto

@@ -10,6 +10,5 @@ message pagemap_entry {
 	required uint64 vaddr		= 1 [(criu).hex = true];
 	required uint32 nr_pages	= 2;
 	optional bool	in_parent	= 3;
-	optional bool	zero		= 4;
-	optional bool	lazy		= 5;
+	optional uint32	flags		= 4 [(criu).hex = true];
 }