[PATCH 2/3] md: factor sb write alignment check into function

[Christopher Unkel <cunkel@xxxxxxxxxxxxxx>]

Refactor in preparation for a second use of the logic.

Signed-off-by: Christopher Unkel <cunkel@xxxxxxxxxxxxxx>
---
 drivers/md/md-bitmap.c | 72 +++++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 32 deletions(-)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 200c5d0f08bf..600b89d5a3ad 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -209,6 +209,44 @@ static struct md_rdev *next_active_rdev(struct md_rdev *rdev, struct mddev *mdde
 	return NULL;
 }
 
+static int sb_write_alignment_ok(struct mddev *mddev, struct md_rdev *rdev,
+				 struct page *page, int offset, int size)
+{
+	if (mddev->external) {
+		/* Bitmap could be anywhere. */
+		if (rdev->sb_start + offset + (page->index
+					       * (PAGE_SIZE/512))
+		    > rdev->data_offset
+		    &&
+		    rdev->sb_start + offset
+		    < (rdev->data_offset + mddev->dev_sectors
+		     + (PAGE_SIZE/512)))
+			return 0;
+	} else if (offset < 0) {
+		/* DATA  BITMAP METADATA  */
+		if (offset
+		    + (long)(page->index * (PAGE_SIZE/512))
+		    + size/512 > 0)
+			/* bitmap runs in to metadata */
+			return 0;
+		if (rdev->data_offset + mddev->dev_sectors
+		    > rdev->sb_start + offset)
+			/* data runs in to bitmap */
+			return 0;
+	} else if (rdev->sb_start < rdev->data_offset) {
+		/* METADATA BITMAP DATA */
+		if (rdev->sb_start
+		    + offset
+		    + page->index*(PAGE_SIZE/512) + size/512
+		    > rdev->data_offset)
+			/* bitmap runs in to data */
+			return 0;
+	} else {
+		/* DATA METADATA BITMAP - no problems */
+	}
+	return 1;
+}
+
 static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
 {
 	struct md_rdev *rdev;
@@ -234,38 +272,8 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
 		/* Just make sure we aren't corrupting data or
 		 * metadata
 		 */
-		if (mddev->external) {
-			/* Bitmap could be anywhere. */
-			if (rdev->sb_start + offset + (page->index
-						       * (PAGE_SIZE/512))
-			    > rdev->data_offset
-			    &&
-			    rdev->sb_start + offset
-			    < (rdev->data_offset + mddev->dev_sectors
-			     + (PAGE_SIZE/512)))
-				goto bad_alignment;
-		} else if (offset < 0) {
-			/* DATA  BITMAP METADATA  */
-			if (offset
-			    + (long)(page->index * (PAGE_SIZE/512))
-			    + size/512 > 0)
-				/* bitmap runs in to metadata */
-				goto bad_alignment;
-			if (rdev->data_offset + mddev->dev_sectors
-			    > rdev->sb_start + offset)
-				/* data runs in to bitmap */
-				goto bad_alignment;
-		} else if (rdev->sb_start < rdev->data_offset) {
-			/* METADATA BITMAP DATA */
-			if (rdev->sb_start
-			    + offset
-			    + page->index*(PAGE_SIZE/512) + size/512
-			    > rdev->data_offset)
-				/* bitmap runs in to data */
-				goto bad_alignment;
-		} else {
-			/* DATA METADATA BITMAP - no problems */
-		}
+		if (!sb_write_alignment_ok(mddev, rdev, page, offset, size))
+			goto bad_alignment;
 		md_super_write(mddev, rdev,
 			       rdev->sb_start + offset
 			       + page->index * (PAGE_SIZE/512),
-- 
2.17.1