md: Make update_size() take the number of sectors.

Changing the internal representations of sizes of raid devices
from 1K blocks to sector counts (512B units) is desirable because
it allows to get rid of many divisions/multiplications and unnecessary
casts that are present in the current code.

This patch is a first step in this direction. It replaces the old
1K-based "size" argument of update_size() by "num_sectors" and
fixes up its two callers.
Signed-off-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: Neil Brown <neilb@suse.de>

drivers/md/md.c

@@ -2890,7 +2890,7 @@ size_show(mddev_t *mddev, char *page)
 	return sprintf(page, "%llu\n", (unsigned long long)mddev->size);
 }
 
-static int update_size(mddev_t *mddev, unsigned long size);
+static int update_size(mddev_t *mddev, sector_t num_sectors);
 
 static ssize_t
 size_store(mddev_t *mddev, const char *buf, size_t len)
@@ -2907,7 +2907,7 @@ size_store(mddev_t *mddev, const char *buf, size_t len)
 		return -EINVAL;
 
 	if (mddev->pers) {
-		err = update_size(mddev, size);
+		err = update_size(mddev, size * 2);
 		md_update_sb(mddev, 1);
 	} else {
 		if (mddev->size == 0 ||
@@ -4617,24 +4617,24 @@ static int set_array_info(mddev_t * mddev, mdu_array_info_t *info)
 	return 0;
 }
 
-static int update_size(mddev_t *mddev, unsigned long size)
+static int update_size(mddev_t *mddev, sector_t num_sectors)
 {
 	mdk_rdev_t * rdev;
 	int rv;
 	struct list_head *tmp;
-	int fit = (size == 0);
+	int fit = (num_sectors == 0);
 
 	if (mddev->pers->resize == NULL)
 		return -EINVAL;
-	/* The "size" is the amount of each device that is used.
-	 * This can only make sense for arrays with redundancy.
-	 * linear and raid0 always use whatever space is available
-	 * We can only consider changing the size if no resync
-	 * or reconstruction is happening, and if the new size
-	 * is acceptable. It must fit before the sb_offset or,
-	 * if that is <data_offset, it must fit before the
-	 * size of each device.
-	 * If size is zero, we find the largest size that fits.
+	/* The "num_sectors" is the number of sectors of each device that
+	 * is used.  This can only make sense for arrays with redundancy.
+	 * linear and raid0 always use whatever space is available. We can only
+	 * consider changing this number if no resync or reconstruction is
+	 * happening, and if the new size is acceptable. It must fit before the
+	 * sb_offset or, if that is <data_offset, it must fit before the size
+	 * of each device.  If num_sectors is zero, we find the largest size
+	 * that fits.
+
 	 */
 	if (mddev->sync_thread)
 		return -EBUSY;
@@ -4642,12 +4642,12 @@ static int update_size(mddev_t *mddev, unsigned long size)
 		sector_t avail;
 		avail = rdev->size * 2;
 
-		if (fit && (size == 0 || size > avail/2))
-			size = avail/2;
-		if (avail < ((sector_t)size << 1))
+		if (fit && (num_sectors == 0 || num_sectors > avail))
+			num_sectors = avail;
+		if (avail < num_sectors)
 			return -ENOSPC;
 	}
-	rv = mddev->pers->resize(mddev, (sector_t)size *2);
+	rv = mddev->pers->resize(mddev, num_sectors);
 	if (!rv) {
 		struct block_device *bdev;
 
@@ -4729,7 +4729,7 @@ static int update_array_info(mddev_t *mddev, mdu_array_info_t *info)
 			return mddev->pers->reconfig(mddev, info->layout, -1);
 	}
 	if (info->size >= 0 && mddev->size != info->size)
-		rv = update_size(mddev, info->size);
+		rv = update_size(mddev, (sector_t)info->size * 2);
 
 	if (mddev->raid_disks    != info->raid_disks)
 		rv = update_raid_disks(mddev, info->raid_disks);