md: Relax minimum size restrictions on chunk_size.

Currently, the 'chunk_size' of an array must be at-least PAGE_SIZE.

This makes moving an array to a machine with a larger PAGE_SIZE, or
changing the kernel to use a larger PAGE_SIZE, can stop an array from
working.

For RAID10 and RAID4/5/6, this is non-trivial to fix as the resync
process works on whole pages at a time, and assumes them to be wholly
within a stripe.  For other raid personalities, this restriction is
not needed at all and can be dropped.

So remove the test on chunk_size from common can, and add it in just
the places where it is needed: raid10 and raid4/5/6.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index a29187d..be2014f 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3520,17 +3520,12 @@ static int do_md_run(mddev_t * mddev)
                        return -EINVAL;
                }
                /*
-                * chunk-size has to be a power of 2 and multiples of PAGE_SIZE
+                * chunk-size has to be a power of 2
                 */
                if ( (1 << ffz(~chunk_size)) != chunk_size) {
                        printk(KERN_ERR "chunk_size of %d not valid\n", chunk_size);
                        return -EINVAL;
                }
-               if (chunk_size < PAGE_SIZE) {
-                       printk(KERN_ERR "too small chunk_size: %d < %ld\n",
-                               chunk_size, PAGE_SIZE);
-                       return -EINVAL;
-               }
 
                /* devices must have minimum size of one chunk */
                rdev_for_each(rdev, tmp, mddev) {

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 8bdc9bf..e379479 100644 (file)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2028,8 +2028,9 @@ static int run(mddev_t *mddev)
        int nc, fc, fo;
        sector_t stride, size;
 
-       if (mddev->chunk_size == 0) {
-               printk(KERN_ERR "md/raid10: non-zero chunk size required.\n");
+       if (mddev->chunk_size < PAGE_SIZE) {
+               printk(KERN_ERR "md/raid10: chunk size must be "
+                      "at least PAGE_SIZE(%ld).\n", PAGE_SIZE);
                return -EINVAL;
        }
 

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index d72be4b..a36a743 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4007,6 +4007,13 @@ static int run(mddev_t *mddev)
                return -EIO;
        }
 
+       if (mddev->chunk_size < PAGE_SIZE) {
+               printk(KERN_ERR "md/raid5: chunk_size must be at least "
+                      "PAGE_SIZE but %d < %ld\n",
+                      mddev->chunk_size, PAGE_SIZE);
+               return -EINVAL;
+       }
+
        if (mddev->reshape_position != MaxSector) {
                /* Check that we can continue the reshape.
                 * Currently only disks can change, it must