[PATCH] md: remove arbitrary limit on chunk size

The largest chunk size the code can support without substantial surgery is
2^30 bytes, so make that the limit instead of an arbitrary 4Meg.  Some day,
the 'chunksize' should change to a sector-shift instead of a byte-count.  Then
no limit would be needed.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/md/raid10.c

@@ -2050,7 +2050,7 @@ static int run(mddev_t *mddev)
 	 * maybe...
 	 */
 	{
-		int stripe = conf->raid_disks * mddev->chunk_size / PAGE_SIZE;
+		int stripe = conf->raid_disks * (mddev->chunk_size / PAGE_SIZE);
 		stripe /= conf->near_copies;
 		if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
 			mddev->queue->backing_dev_info.ra_pages = 2* stripe;

drivers/md/raid5.c

@@ -2382,8 +2382,8 @@ static int run(mddev_t *mddev)
 	 * 2 * (n-1) * chunksize where 'n' is the number of raid devices
 	 */
 	{
-		int stripe = (mddev->raid_disks-1) * mddev->chunk_size
-			/ PAGE_SIZE;
+		int stripe = (mddev->raid_disks-1) *
+			(mddev->chunk_size / PAGE_SIZE);
 		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
 			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
 	}

drivers/md/raid6main.c

@@ -2135,8 +2135,8 @@ static int run(mddev_t *mddev)
 	 * 2 * (n-2) * chunksize where 'n' is the number of raid devices
 	 */
 	{
-		int stripe = (mddev->raid_disks-2) * mddev->chunk_size
-			/ PAGE_SIZE;
+		int stripe = (mddev->raid_disks-2) *
+			(mddev->chunk_size / PAGE_SIZE);
 		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
 			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
 	}

include/linux/raid/md_k.h

@@ -40,7 +40,8 @@ typedef struct mdk_rdev_s mdk_rdev_t;
  * options passed in raidrun:
  */
 
-#define MAX_CHUNK_SIZE (4096*1024)
+/* Currently this must fix in an 'int' */
+#define MAX_CHUNK_SIZE (1<<30)
 
 /*
  * MD's 'extended' device