[CRIU] [PATCH] deduplication: bunch neighbour data to punch together

[Tikhomirov Pavel]

when decide that data is no longer needed, there are two cases:
1. if data neighbours previous block of "no needed" data, extend bunch
block(it holds begining and size of concequent "no needed" data) by
length of curent block and go next.
2. if data not neighbours bunch block(or bunch block size is bigger
than MAX_BUNCH_SIZE), than punch bunch block and set bunch block
to curent block.

in the end make cleanup to punch last bunch block.

Signed-off-by: Tikhomirov Pavel <snorcht at gmail.com>
---
 cr-dedup.c          | 34 ++++++++++++++++++++++++++--------
 include/page-read.h |  5 ++++-
 page-read.c         | 14 +++++++++++++-
 3 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/cr-dedup.c b/cr-dedup.c
index 6f059d1..9d269d2 100644
--- a/cr-dedup.c
+++ b/cr-dedup.c
@@ -7,6 +7,8 @@
 #include "page-read.h"
 #include "restorer.h"
 
+#define MAX_BUNCH_SIZE 256
+
 static int cr_dedup_one_pagemap(int pid);
 
 int cr_dedup(void)
@@ -101,15 +103,30 @@ exit:
 	return 0;
 }
 
-int punch_hole(int fd, unsigned long off, unsigned long len)
+int punch_hole(int fd, unsigned long off, unsigned long len,
+	       struct iovec * bunch, bool cleanup, int pr_id)
 {
 	int ret;
-	pr_debug("Punch!/%lu/%lu/\n", off, len);
-	ret = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
-			off, len);
-	if (ret != 0) {
-		pr_perror("Error punching hole");
-		return -1;
+
+	if ((unsigned long)bunch->iov_base + bunch->iov_len == off && !cleanup
+	    && bunch->iov_len < MAX_BUNCH_SIZE * PAGE_SIZE) {
+		pr_debug("pr%d:Extend bunch len from %lx to %lx\n", pr_id,
+			 bunch->iov_len, bunch->iov_len + len);
+		bunch->iov_len += len;
+	} else {
+		if (bunch->iov_len > 0) {
+			pr_debug("Punch!/%lx/%lx/\n", (unsigned long)bunch->iov_base, bunch->iov_len);
+			ret = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+					(unsigned long)bunch->iov_base, bunch->iov_len);
+			if (ret != 0) {
+				pr_perror("Error punching hole");
+				return -1;
+			}
+		}
+		bunch->iov_base = (void *)off;
+		bunch->iov_len = len;
+		pr_debug("pr%d:New bunch/%lx/%lx/\n", pr_id,
+			 (unsigned long)bunch->iov_base, bunch->iov_len);
 	}
 	return 0;
 }
@@ -146,7 +163,8 @@ int dedup_one_iovec(struct page_read *pr, struct iovec *iov)
 		piov_end = (unsigned long)piov.iov_base + piov.iov_len;
 		off_real = lseek(pr->fd_pg, 0, SEEK_CUR);
 		if (!pr->pe->in_parent) {
-			ret = punch_hole(pr->fd_pg, off_real, min(piov_end, iov_end) - off);
+			ret = punch_hole(pr->fd_pg, off_real, min(piov_end, iov_end) - off,
+				         &pr->bunch, false, pr->id);
 			if (ret == -1)
 				return ret;
 		}
diff --git a/include/page-read.h b/include/page-read.h
index 8b467c6..28435c7 100644
--- a/include/page-read.h
+++ b/include/page-read.h
@@ -63,6 +63,8 @@ struct page_read {
 					   read_pagemap_page */
 	unsigned long cvaddr;		/* vaddr we are on */
 
+	struct iovec bunch;		/* record consequent neighbour
+					   iovecs to punch together */
 	unsigned id; /* for logging */
 };
 
@@ -72,5 +74,6 @@ extern void pagemap2iovec(PagemapEntry *pe, struct iovec *iov);
 extern int seek_pagemap_page(struct page_read *pr, unsigned long vaddr, bool warn);
 
 extern int dedup_one_iovec(struct page_read *pr, struct iovec *iov);
-extern int punch_hole(int fd, unsigned long off, unsigned long len);
+extern int punch_hole(int fd, unsigned long off, unsigned long len,
+		      struct iovec * bunch, bool cleanup, int pr_id);
 #endif /* __CR_PAGE_READ_H__ */
diff --git a/page-read.c b/page-read.c
index e2514d6..0fd3464 100644
--- a/page-read.c
+++ b/page-read.c
@@ -149,7 +149,8 @@ static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, void *bu
 		}
 
 		if (opts.auto_dedup) {
-			ret = punch_hole(pr->fd_pg, current_vaddr, (unsigned int)PAGE_SIZE);
+			ret = punch_hole(pr->fd_pg, current_vaddr, (unsigned int)PAGE_SIZE,
+					 &pr->bunch, false, pr->id);
 			if (ret == -1) {
 				return -1;
 			}
@@ -163,6 +164,15 @@ static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, void *bu
 
 static void close_page_read(struct page_read *pr)
 {
+	int ret;
+	if (pr->bunch.iov_len > 0) {
+		ret = punch_hole(pr->fd_pg, 0, 0, &pr->bunch, true, pr->id);
+		if (ret == -1)
+			return;
+
+		pr->bunch.iov_len = 0;
+	}
+
 	if (pr->parent) {
 		close_page_read(pr->parent);
 		xfree(pr->parent);
@@ -207,6 +217,8 @@ err_cl:
 int open_page_read_at(int dfd, int pid, struct page_read *pr, int flags)
 {
 	pr->pe = NULL;
+	pr->bunch.iov_len = 0;
+	pr->bunch.iov_base = NULL;
 
 	pr->fd = open_image_at(dfd, CR_FD_PAGEMAP, O_RSTR, (long)pid);
 	if (pr->fd < 0) {
-- 
1.8.3.2