[CRIU] [PATCH 2/3] page-read: Add async arg to ->read_pages callback

[Pavel Emelyanov]

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

Flag PR_UNPLUG means, that the caller nonetheless wants the
data to be available ASAP.

Signed-off-by: Pavel Emelyanov <xemul at virtuozzo.com>
---
 criu/include/pagemap.h | 6 +++++-
 criu/mem.c             | 4 ++--
 criu/pagemap.c         | 5 +++--
 criu/shmem.c           | 2 +-
 criu/uffd.c            | 2 +-
 5 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/criu/include/pagemap.h b/criu/include/pagemap.h
index 705a9af..b445d82 100644
--- a/criu/include/pagemap.h
+++ b/criu/include/pagemap.h
@@ -47,7 +47,7 @@ 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 *);
 	void (*skip_pages)(struct page_read *, unsigned long len);
 	int (*seek_page)(struct page_read *pr, unsigned long vaddr, bool warn);
@@ -74,6 +74,10 @@ struct page_read {
 	int curr_pme;
 };
 
+/* flags for ->read_pages */
+#define PR_ASYNC	0x1 /* may exit w/o data in the buffer */
+#define PR_UNPLUG	0x2 /* do async, but start the IO asap */
+
 #define PR_SHMEM	0x1
 #define PR_TASK		0x2
 
diff --git a/criu/mem.c b/criu/mem.c
index 809b637..7da64f5 100644
--- a/criu/mem.c
+++ b/criu/mem.c
@@ -790,7 +790,7 @@ 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;
 
@@ -818,7 +818,7 @@ 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;
 
diff --git a/criu/pagemap.c b/criu/pagemap.c
index cfc9659..0a072c8 100644
--- a/criu/pagemap.c
+++ b/criu/pagemap.c
@@ -205,7 +205,8 @@ static inline void pagemap_bound_check(PagemapEntry *pe, unsigned long vaddr, in
 	}
 }
 
-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)
 {
 	int ret;
 	unsigned long len = nr * PAGE_SIZE;
@@ -242,7 +243,7 @@ static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, int nr,
 			if (p_nr > nr)
 				p_nr = nr;
 
-			ret = read_pagemap_page(ppr, vaddr, p_nr, buf);
+			ret = read_pagemap_page(ppr, vaddr, p_nr, buf, flags);
 			if (ret == -1)
 				return ret;
 
diff --git a/criu/shmem.c b/criu/shmem.c
index 5065abd..05028a3 100644
--- a/criu/shmem.c
+++ b/criu/shmem.c
@@ -485,7 +485,7 @@ 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);
diff --git a/criu/uffd.c b/criu/uffd.c
index e6d4069..3336651 100644
--- a/criu/uffd.c
+++ b/criu/uffd.c
@@ -398,7 +398,7 @@ static int get_page(struct lazy_pages_info *lpi, unsigned long addr, void *dest)
 	if (pagemap_zero(lpi->pr.pe))
 		return 0;
 
-	ret = lpi->pr.read_pages(&lpi->pr, addr, 1, buf);
+	ret = lpi->pr.read_pages(&lpi->pr, addr, 1, buf, 0);
 	pr_debug("read_pages ret %d\n", ret);
 	if (ret <= 0)
 		return ret;
-- 
2.1.4