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>

3 files changed, 72 insertions, 53 deletions

diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c
index 96366a1d7eae..5a62420cbdb1 100644
--- a/fs/exofs/inode.c
+++ b/fs/exofs/inode.c
@@ -37,11 +37,7 @@
 
 #define EXOFS_DBGMSG2(M...) do {} while (0)
 
-enum { BIO_MAX_PAGES_KMALLOC =
-                (PAGE_SIZE - sizeof(struct bio)) / sizeof(struct bio_vec),
-        MAX_PAGES_KMALLOC =
-                PAGE_SIZE / sizeof(struct page *),
-};
+enum {MAX_PAGES_KMALLOC = PAGE_SIZE / sizeof(struct page *), };
 
 unsigned exofs_max_io_pages(struct ore_layout *layout,
                             unsigned expected_pages)
@@ -49,8 +45,7 @@ unsigned exofs_max_io_pages(struct ore_layout *layout,
         unsigned pages = min_t(unsigned, expected_pages, MAX_PAGES_KMALLOC);
 
         /* TODO: easily support bio chaining */
-        pages =  min_t(unsigned, pages,
-                       layout->group_width * BIO_MAX_PAGES_KMALLOC);
+        pages =  min_t(unsigned, pages, layout->max_io_length / PAGE_SIZE);
         return pages;
 }
 
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;
diff --git a/fs/exofs/super.c b/fs/exofs/super.c
index bce3686f0aa0..057b237b8b69 100644
--- a/fs/exofs/super.c
+++ b/fs/exofs/super.c
@@ -480,7 +480,7 @@ static void exofs_put_super(struct super_block *sb)
 static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
                                     struct exofs_device_table *dt)
 {
-        u64 stripe_length;
+        int ret;
 
         sbi->layout.stripe_unit =
                                 le64_to_cpu(dt->dt_data_map.cb_stripe_unit);
@@ -493,50 +493,7 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
         sbi->layout.raid_algorithm  =
                                 le32_to_cpu(dt->dt_data_map.cb_raid_algorithm);
 
-/* FIXME: Only raid0 for now. if not so, do not mount */
-        if (sbi->layout.raid_algorithm != PNFS_OSD_RAID_0) {
-                EXOFS_ERR("Only RAID_0 for now\n");
-                return -EINVAL;
-        }
-        if (numdevs < (sbi->layout.group_width * sbi->layout.mirrors_p1)) {
-                EXOFS_ERR("Data Map wrong, "
-                          "numdevs=%d < group_width=%d * mirrors=%d\n",
-                          numdevs, sbi->layout.group_width,
-                          sbi->layout.mirrors_p1);
-                return -EINVAL;
-        }
-
-        if (0 != (sbi->layout.stripe_unit & ~PAGE_MASK)) {
-                EXOFS_ERR("Stripe Unit(0x%llx)"
-                          " must be Multples of PAGE_SIZE(0x%lx)\n",
-                          _LLU(sbi->layout.stripe_unit), PAGE_SIZE);
-                return -EINVAL;
-        }
-
-        if (sbi->layout.group_width) {
-                if (!sbi->layout.group_depth) {
-                        EXOFS_ERR("group_depth == 0 && group_width != 0\n");
-                        return -EINVAL;
-                }
-                sbi->layout.group_count = numdevs / sbi->layout.mirrors_p1 /
-                                                sbi->layout.group_width;
-        } else {
-                if (sbi->layout.group_depth) {
-                        printk(KERN_NOTICE "Warning: group_depth ignored "
-                                "group_width == 0 && group_depth == %lld\n",
-                                _LLU(sbi->layout.group_depth));
-                }
-                sbi->layout.group_width = numdevs / sbi->layout.mirrors_p1;
-                sbi->layout.group_depth = -1;
-                sbi->layout.group_count = 1;
-        }
-
-        stripe_length = (u64)sbi->layout.group_width * sbi->layout.stripe_unit;
-        if (stripe_length >= (1ULL << 32)) {
-                EXOFS_ERR("Total Stripe length(0x%llx)"
-                          " >= 32bit is not supported\n", _LLU(stripe_length));
-                return -EINVAL;
-        }
+        ret = ore_verify_layout(numdevs, &sbi->layout);
 
         EXOFS_DBGMSG("exofs: layout: "
                 "num_comps=%u stripe_unit=0x%x group_width=%u "
@@ -547,7 +504,7 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
                 _LLU(sbi->layout.group_depth),
                 sbi->layout.mirrors_p1,
                 sbi->layout.raid_algorithm);
-        return 0;
+        return ret;
 }
 
 static unsigned __ra_pages(struct ore_layout *layout)