exofs: groups support

* _calc_stripe_info() changes to accommodate for grouping
  calculations. Returns additional information

* old _prepare_pages() becomes _prepare_one_group()
  which stores pages belonging to one device group.

* New _prepare_for_striping iterates on all groups calling
  _prepare_one_group().

* Enable mounting of groups data_maps (group_width != 0)

[QUESTION]
what is faster A or B;
A.	x += stride;
	x = x % width + first_x;

B	x += stride
	if (x < last_x)
		x = first_x;

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

1 files changed, 32 insertions, 14 deletions

diff --git a/fs/exofs/super.c b/fs/exofs/super.c
index 8f4e4b37a578..6cf5e4e84d61 100644
--- a/fs/exofs/super.c
+++ b/fs/exofs/super.c
@@ -323,11 +323,7 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
         sbi->data_map.odm_raid_algorithm  =
                                 le32_to_cpu(dt->dt_data_map.cb_raid_algorithm);
 
-/* FIXME: Only raid0 !group_width/depth for now. if not so, do not mount */
-        if (sbi->data_map.odm_group_width || sbi->data_map.odm_group_depth) {
-                EXOFS_ERR("Group width/depth not supported\n");
-                return -EINVAL;
-        }
+/* FIXME: Only raid0 for now. if not so, do not mount */
         if (sbi->data_map.odm_num_comps != numdevs) {
                 EXOFS_ERR("odm_num_comps(%u) != numdevs(%u)\n",
                           sbi->data_map.odm_num_comps, numdevs);
@@ -343,14 +339,6 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
                 return -EINVAL;
         }
 
-        stripe_length = sbi->data_map.odm_stripe_unit *
-                        (numdevs / (sbi->data_map.odm_mirror_cnt + 1));
-        if (stripe_length >= (1ULL << 32)) {
-                EXOFS_ERR("Total Stripe length(0x%llx)"
-                          " >= 32bit is not supported\n", _LLU(stripe_length));
-                return -EINVAL;
-        }
-
         if (0 != (sbi->data_map.odm_stripe_unit & ~PAGE_MASK)) {
                 EXOFS_ERR("Stripe Unit(0x%llx)"
                           " must be Multples of PAGE_SIZE(0x%lx)\n",
@@ -360,8 +348,36 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
 
         sbi->layout.stripe_unit = sbi->data_map.odm_stripe_unit;
         sbi->layout.mirrors_p1 = sbi->data_map.odm_mirror_cnt + 1;
-        sbi->layout.group_width = sbi->data_map.odm_num_comps /
+
+        if (sbi->data_map.odm_group_width) {
+                sbi->layout.group_width = sbi->data_map.odm_group_width;
+                sbi->layout.group_depth = sbi->data_map.odm_group_depth;
+                if (!sbi->layout.group_depth) {
+                        EXOFS_ERR("group_depth == 0 && group_width != 0\n");
+                        return -EINVAL;
+                }
+                sbi->layout.group_count = sbi->data_map.odm_num_comps /
+                                                sbi->layout.mirrors_p1 /
+                                                sbi->data_map.odm_group_width;
+        } else {
+                if (sbi->data_map.odm_group_depth) {
+                        printk(KERN_NOTICE "Warning: group_depth ignored "
+                                "group_width == 0 && group_depth == %d\n",
+                                sbi->data_map.odm_group_depth);
+                        sbi->data_map.odm_group_depth = 0;
+                }
+                sbi->layout.group_width = sbi->data_map.odm_num_comps /
                                                         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;
+        }
 
         return 0;
 }
@@ -540,6 +556,8 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
         sbi->layout.stripe_unit = PAGE_SIZE;
         sbi->layout.mirrors_p1 = 1;
         sbi->layout.group_width = 1;
+        sbi->layout.group_depth = -1;
+        sbi->layout.group_count = 1;
         sbi->layout.s_ods[0] = od;
         sbi->layout.s_numdevs = 1;
         sbi->layout.s_pid = opts->pid;