ore/exofs: Define new ore_verify_layout

All users of the ore will need to check if current code
supports the given layout. For example RAID5/6 is not
currently supported.

So move all the checks from exofs/super.c to a new
ore_verify_layout() to be used by ore users.

Note that any new layout should be passed through the
ore_verify_layout() because the ore engine will prepare
and verify some internal members of ore_layout, and
assumes it's called.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

1 files changed, 67 insertions, 0 deletions

diff --git a/fs/exofs/ore.c b/fs/exofs/ore.c
index f1b718028a1f..4ca59d492798 100644
--- a/fs/exofs/ore.c
+++ b/fs/exofs/ore.c
@@ -47,9 +47,76 @@ MODULE_AUTHOR("Boaz Harrosh <bharrosh@panasas.com>");
 MODULE_DESCRIPTION("Objects Raid Engine ore.ko");
 MODULE_LICENSE("GPL");
 
+/* ore_verify_layout does a couple of things:
+ * 1. Given a minimum number of needed parameters fixes up the rest of the
+ *    members to be operatonals for the ore. The needed parameters are those
+ *    that are defined by the pnfs-objects layout STD.
+ * 2. Check to see if the current ore code actually supports these parameters
+ *    for example stripe_unit must be a multple of the system PAGE_SIZE,
+ *    and etc...
+ * 3. Cache some havily used calculations that will be needed by users.
+ */
+
 static void ore_calc_stripe_info(struct ore_layout *layout, u64 file_offset,
                                  struct ore_striping_info *si);
 
+enum { BIO_MAX_PAGES_KMALLOC =
+                (PAGE_SIZE - sizeof(struct bio)) / sizeof(struct bio_vec),};
+
+int ore_verify_layout(unsigned total_comps, struct ore_layout *layout)
+{
+        u64 stripe_length;
+
+/* FIXME: Only raid0 is supported for now. */
+        if (layout->raid_algorithm != PNFS_OSD_RAID_0) {
+                ORE_ERR("Only RAID_0 for now\n");
+                return -EINVAL;
+        }
+        if (0 != (layout->stripe_unit & ~PAGE_MASK)) {
+                ORE_ERR("Stripe Unit(0x%llx)"
+                          " must be Multples of PAGE_SIZE(0x%lx)\n",
+                          _LLU(layout->stripe_unit), PAGE_SIZE);
+                return -EINVAL;
+        }
+        if (layout->group_width) {
+                if (!layout->group_depth) {
+                        ORE_ERR("group_depth == 0 && group_width != 0\n");
+                        return -EINVAL;
+                }
+                if (total_comps < (layout->group_width * layout->mirrors_p1)) {
+                        ORE_ERR("Data Map wrong, "
+                                "numdevs=%d < group_width=%d * mirrors=%d\n",
+                                total_comps, layout->group_width,
+                                layout->mirrors_p1);
+                        return -EINVAL;
+                }
+                layout->group_count = total_comps / layout->mirrors_p1 /
+                                                layout->group_width;
+        } else {
+                if (layout->group_depth) {
+                        printk(KERN_NOTICE "Warning: group_depth ignored "
+                                "group_width == 0 && group_depth == %lld\n",
+                                _LLU(layout->group_depth));
+                }
+                layout->group_width = total_comps / layout->mirrors_p1;
+                layout->group_depth = -1;
+                layout->group_count = 1;
+        }
+
+        stripe_length = (u64)layout->group_width * layout->stripe_unit;
+        if (stripe_length >= (1ULL << 32)) {
+                ORE_ERR("Stripe_length(0x%llx) >= 32bit is not supported\n",
+                        _LLU(stripe_length));
+                return -EINVAL;
+        }
+
+        layout->max_io_length =
+                (BIO_MAX_PAGES_KMALLOC * PAGE_SIZE - layout->stripe_unit) *
+                                                        layout->group_width;
+        return 0;
+}
+EXPORT_SYMBOL(ore_verify_layout);
+
 static u8 *_ios_cred(struct ore_io_state *ios, unsigned index)
 {
         return ios->oc->comps[index & ios->oc->single_comp].cred;