DDF: add_to_super_ddf: allow empty slots in phys disk table

The used slots in the phys disk table aren't necessarily the
first ones. Rather, unused entries are represented by entries
where the GUID is all 0xff.

Signed-off-by: Martin Wilck <mwilck@arcor.de>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 23 insertions, 6 deletions

diff --git a/super-ddf.c b/super-ddf.c
index 617f83f5..028229f0 100644
--- a/super-ddf.c
+++ b/super-ddf.c
@@ -2245,6 +2245,8 @@ static int init_super_ddf(struct supertype *st,
 	pd->used_pdes = __cpu_to_be16(0);
 	pd->max_pdes = __cpu_to_be16(max_phys_disks);
 	memset(pd->pad, 0xff, 52);
+	for (i = 0; i < max_phys_disks; i++)
+		memset(pd->entries[i].guid, 0xff, DDF_GUID_LEN);
 
 	if (posix_memalign((void**)&vd, 512, vdsize) != 0) {
 		pr_err("%s could not allocate vd\n", __func__);
@@ -2541,6 +2543,16 @@ static void add_to_super_ddf_bvd(struct supertype *st,
 	ddf_set_updates_pending(ddf);
 }
 
+static unsigned int find_unused_pde(const struct ddf_super *ddf)
+{
+	unsigned int i;
+	for (i = 0; i < __be16_to_cpu(ddf->phys->max_pdes); i++) {
+		if (all_ff(ddf->phys->entries[i].guid))
+			return i;
+	}
+	return DDF_NOTFOUND;
+}
+
 /* add a device to a container, either while creating it or while
  * expanding a pre-existing container
  */
@@ -2567,6 +2579,14 @@ static int add_to_super_ddf(struct supertype *st,
 	 * a phys_disk entry and a more detailed disk_data entry.
 	 */
 	fstat(fd, &stb);
+	n = find_unused_pde(ddf);
+	if (n == DDF_NOTFOUND) {
+		pr_err("%s: No free slot in array, cannot add disk\n",
+		       __func__);
+		return 1;
+	}
+	pde = &ddf->phys->entries[n];
+
 	if (posix_memalign((void**)&dd, 512,
 		           sizeof(*dd) + sizeof(dd->vlist[0]) * ddf->max_part) != 0) {
 		pr_err("%s could allocate buffer for new disk, aborting\n",
@@ -2605,8 +2625,6 @@ static int add_to_super_ddf(struct supertype *st,
 	for (i = 0; i < ddf->max_part ; i++)
 		dd->vlist[i] = NULL;
 
-	n = __be16_to_cpu(ddf->phys->used_pdes);
-	pde = &ddf->phys->entries[n];
 	dd->pdnum = n;
 
 	if (st->update_tail) {
@@ -2619,10 +2637,9 @@ static int add_to_super_ddf(struct supertype *st,
 		pd->used_pdes = __cpu_to_be16(n);
 		pde = &pd->entries[0];
 		dd->mdupdate = pd;
-	} else {
-		n++;
-		ddf->phys->used_pdes = __cpu_to_be16(n);
-	}
+	} else
+		ddf->phys->used_pdes = __cpu_to_be16(
+			1 + __be16_to_cpu(ddf->phys->used_pdes));
 
 	memcpy(pde->guid, dd->disk.guid, DDF_GUID_LEN);
 	pde->refnum = dd->disk.refnum;