[Ocfs2-tools-devel] [PATCH 1/2] o2image: allocate bitmap blocks only for metadata blocks when backing-up

[piaojun]

Allocate bitmap blocks for all the filesystem blocks will cost lots of
memory, e.g. 64T LUN will cost 2G memory. And that will cause OOM when
multi-o2image processes run at the same time. We could allocate bitmap
blocks only for metadata blocks to save lots of memory.

Signed-off-by: Jun Piao <piaojun at huawei.com>
---
 include/ocfs2/image.h |  1 -
 libocfs2/image.c      | 66 ++++++++-------------------------------------------
 o2image/o2image.c     | 15 ++++++++----
 3 files changed, 20 insertions(+), 62 deletions(-)

diff --git a/include/ocfs2/image.h b/include/ocfs2/image.h
index 1acc191..ee4acbc 100644
--- a/include/ocfs2/image.h
+++ b/include/ocfs2/image.h
@@ -77,7 +77,6 @@ struct ocfs2_image_hdr {
  */
 struct _ocfs2_image_bitmap_arr {
 	uint64_t	arr_set_bit_cnt;
-	char		*arr_self;
 	char    	*arr_map;
 };
 typedef struct _ocfs2_image_bitmap_arr ocfs2_image_bitmap_arr;
diff --git a/libocfs2/image.c b/libocfs2/image.c
index 872bdb3..68f4fda 100644
--- a/libocfs2/image.c
+++ b/libocfs2/image.c
@@ -70,8 +70,8 @@ void ocfs2_image_free_bitmap(ocfs2_filesys *ofs)
 		return;

 	for (i=0; i<ost->ost_bmpblks; i++)
-		if (ost->ost_bmparr[i].arr_self)
-			ocfs2_free(&ost->ost_bmparr[i].arr_self);
+		if (ost->ost_bmparr[i].arr_map)
+			ocfs2_free(&ost->ost_bmparr[i].arr_map);

 	if (ost->ost_bmparr)
 		ocfs2_free(&ost->ost_bmparr);
@@ -85,11 +85,9 @@ void ocfs2_image_free_bitmap(ocfs2_filesys *ofs)
  */
 errcode_t ocfs2_image_alloc_bitmap(ocfs2_filesys *ofs)
 {
-	uint64_t blks, allocsize, leftsize;
+	uint64_t blks;
 	struct ocfs2_image_state *ost = ofs->ost;
-	int indx, i, n;
 	errcode_t ret;
-	char *buf;

 	ost->ost_bmpblks =
 		((ost->ost_fsblkcnt - 1) / (OCFS2_IMAGE_BITS_IN_BLOCK)) + 1;
@@ -99,56 +97,6 @@ errcode_t ocfs2_image_alloc_bitmap(ocfs2_filesys *ofs)
 	/* allocate memory for an array to track bitmap blocks */
 	ret = ocfs2_malloc0((blks * sizeof(ocfs2_image_bitmap_arr)),
 			    &ost->ost_bmparr);
-	if (ret)
-		return ret;
-
-	allocsize = blks * OCFS2_IMAGE_BITMAP_BLOCKSIZE;
-	leftsize = allocsize;
-	indx = 0;
-
-	/* allocate bitmap blocks and assign blocks to above array */
-	while (leftsize) {
-		ret = ocfs2_malloc_blocks(ofs->fs_io,
-					  allocsize/io_get_blksize(ofs->fs_io),
-					  &buf);
-		if (ret && (ret != -ENOMEM))
-			goto out;
-
-		if (ret == -ENOMEM) {
-			if (allocsize == OCFS2_IMAGE_BITMAP_BLOCKSIZE)
-				goto out;
-			allocsize >>= 1;
-			if (allocsize % OCFS2_IMAGE_BITMAP_BLOCKSIZE) {
-				allocsize /= OCFS2_IMAGE_BITMAP_BLOCKSIZE;
-				allocsize *= OCFS2_IMAGE_BITMAP_BLOCKSIZE;
-			}
-			continue;
-		}
-
-		n = allocsize / OCFS2_IMAGE_BITMAP_BLOCKSIZE;
-		for (i = 0; i < n; i++) {
-			ost->ost_bmparr[indx].arr_set_bit_cnt = 0;
-			ost->ost_bmparr[indx].arr_map =
-				((char *)buf + (i *
-						OCFS2_IMAGE_BITMAP_BLOCKSIZE));
-
-			/* remember buf address to free it later */
-			if (!i)
-				ost->ost_bmparr[indx].arr_self = buf;
-			indx++;
-		}
-		leftsize -= allocsize;
-		if (leftsize <= allocsize)
-			allocsize = leftsize;
-	}
-out:
-	/* If allocation failed free and return error */
-	if (leftsize) {
-		for (i = 0; i < indx; i++)
-			if (ost->ost_bmparr[i].arr_self)
-				ocfs2_free(&ost->ost_bmparr[i].arr_self);
-		ocfs2_free(&ost->ost_bmparr);
-	}

 	return ret;
 }
@@ -251,6 +199,11 @@ void ocfs2_image_mark_bitmap(ocfs2_filesys *ofs, uint64_t blkno)
 	bit = blkno % OCFS2_IMAGE_BITS_IN_BLOCK;
 	bitmap_blk = blkno / OCFS2_IMAGE_BITS_IN_BLOCK;

+	if (!ost->ost_bmparr[bitmap_blk].arr_map) {
+		ocfs2_malloc0(ost->ost_bmpblksz,
+				   &ost->ost_bmparr[bitmap_blk].arr_map);
+	}
+
 	ocfs2_set_bit(bit, ost->ost_bmparr[bitmap_blk].arr_map);
 }

@@ -263,7 +216,8 @@ int ocfs2_image_test_bit(ocfs2_filesys *ofs, uint64_t blkno)
 	bit = blkno % OCFS2_IMAGE_BITS_IN_BLOCK;
 	bitmap_blk = blkno / OCFS2_IMAGE_BITS_IN_BLOCK;

-	if (ocfs2_test_bit(bit, ost->ost_bmparr[bitmap_blk].arr_map))
+	if (ost->ost_bmparr[bitmap_blk].arr_map &&
+			   ocfs2_test_bit(bit, ost->ost_bmparr[bitmap_blk].arr_map))
 		return 1;
 	else
 		return 0;
diff --git a/o2image/o2image.c b/o2image/o2image.c
index 1dd16ed..15e0d2d 100644
--- a/o2image/o2image.c
+++ b/o2image/o2image.c
@@ -602,8 +602,11 @@ static errcode_t write_image_file(ocfs2_filesys *ofs, int fd)
 	}
 	/* write bitmap blocks at the end */
 	for(blk = 0; blk < ost->ost_bmpblks; blk++) {
-		bytes = write(fd, ost->ost_bmparr[blk].arr_map,
-			      ost->ost_bmpblksz);
+		if (ost->ost_bmparr[blk].arr_map)
+			bytes = write(fd, ost->ost_bmparr[blk].arr_map,
+				      ost->ost_bmpblksz);
+		else
+			lseek(fd, ost->ost_bmpblksz, SEEK_CUR);
 		if ((bytes == -1) || (bytes < ost->ost_bmpblksz)) {
 			com_err(program_name, errno, "error writing bitmap "
 				"blk %"PRIu64" bytes %u", blk, bytes);
@@ -637,9 +640,11 @@ static errcode_t scan_raw_disk(ocfs2_filesys *ofs)
 	/* update set_bit_cnt for future use */
 	for (i = 0; i < ost->ost_bmpblks; i++) {
 		ost->ost_bmparr[i].arr_set_bit_cnt = bits_set;
-		for (j = 0; j < (ost->ost_bmpblksz * 8); j++)
-			if (ocfs2_test_bit(j, ost->ost_bmparr[i].arr_map))
-				bits_set++;
+		if (ost->ost_bmparr[i].arr_map) {
+			for (j = 0; j < (ost->ost_bmpblksz * 8); j++)
+				if (ocfs2_test_bit(j, ost->ost_bmparr[i].arr_map))
+					bits_set++;
+		}
 	}

 out:
--