1 files changed, 106 insertions, 23 deletions

diff --git a/fs/exofs/ios.c b/fs/exofs/ios.c
index d28febdf54ab..5293bc411d17 100644
--- a/fs/exofs/ios.c
+++ b/fs/exofs/ios.c
@@ -262,25 +262,50 @@ int exofs_check_io(struct exofs_io_state *ios, u64 *resid)
 /*
  * L - logical offset into the file
  *
- * U - The number of bytes in a full stripe
+ * U - The number of bytes in a stripe within a group
  *
  *      U = stripe_unit * group_width
  *
- * N - The stripe number
+ * T - The number of bytes striped within a group of component objects
+ *     (before advancing to the next group)
  *
- *      N = L / U
+ *      T = stripe_unit * group_width * group_depth
+ *
+ * S - The number of bytes striped across all component objects
+ *     before the pattern repeats
+ *
+ *      S = stripe_unit * group_width * group_depth * group_count
+ *
+ * M - The "major" (i.e., across all components) stripe number
+ *
+ *      M = L / S
+ *
+ * G - Counts the groups from the beginning of the major stripe
+ *
+ *      G = (L - (M * S)) / T   [or (L % S) / T]
+ *
+ * H - The byte offset within the group
+ *
+ *      H = (L - (M * S)) % T   [or (L % S) % T]
+ *
+ * N - The "minor" (i.e., across the group) stripe number
+ *
+ *      N = H / U
  *
  * C - The component index coresponding to L
  *
- *      C = (L - (N*U)) / stripe_unit
+ *      C = (H - (N * U)) / stripe_unit + G * group_width
+ *      [or (L % U) / stripe_unit + G * group_width]
  *
  * O - The component offset coresponding to L
  *
- *      (N*stripe_unit)+(L%stripe_unit)
+ *      O = L % stripe_unit + N * stripe_unit + M * group_depth * stripe_unit
  */
-
 struct _striping_info {
         u64 obj_offset;
+        u64 group_length;
+        u64 total_group_length;
+        u64 Major;
         unsigned dev;
         unsigned unit_off;
 };
@@ -290,15 +315,35 @@ static void _calc_stripe_info(struct exofs_io_state *ios, u64 file_offset,
 {
         u32     stripe_unit = ios->layout->stripe_unit;
         u32     group_width = ios->layout->group_width;
+        u64     group_depth = ios->layout->group_depth;
+
         u32     U = stripe_unit * group_width;
+        u64     T = U * group_depth;
+        u64     S = T * ios->layout->group_count;
+        u64     M = div64_u64(file_offset, S);
+
+        /*
+        G = (L - (M * S)) / T
+        H = (L - (M * S)) % T
+        */
+        u64     LmodS = file_offset - M * S;
+        u32     G = div64_u64(LmodS, T);
+        u64     H = LmodS - G * T;
+
+        u32     N = div_u64(H, U);
+
+        /* "H - (N * U)" is just "H % U" so it's bound to u32 */
+        si->dev = (u32)(H - (N * U)) / stripe_unit + G * group_width;
+        si->dev *= ios->layout->mirrors_p1;
 
-        u32     LmodU;
-        u64     N = div_u64_rem(file_offset, U, &LmodU);
+        div_u64_rem(file_offset, stripe_unit, &si->unit_off);
 
-        si->unit_off = LmodU % stripe_unit;
-        si->obj_offset = N * stripe_unit + si->unit_off;
-        si->dev = LmodU / stripe_unit;
-        si->dev *= ios->layout->mirrors_p1;
+        si->obj_offset = si->unit_off + (N * stripe_unit) +
+                                  (M * group_depth * stripe_unit);
+
+        si->group_length = T - H;
+        si->total_group_length = T;
+        si->Major = M;
 }
 
 static int _add_stripe_unit(struct exofs_io_state *ios,  unsigned *cur_pg,
@@ -345,16 +390,17 @@ static int _add_stripe_unit(struct exofs_io_state *ios,  unsigned *cur_pg,
         return 0;
 }
 
-static int _prepare_pages(struct exofs_io_state *ios,
-                          struct _striping_info *si)
+static int _prepare_one_group(struct exofs_io_state *ios, u64 length,
+                              struct _striping_info *si, unsigned first_comp)
 {
-        u64 length = ios->length;
         unsigned stripe_unit = ios->layout->stripe_unit;
         unsigned mirrors_p1 = ios->layout->mirrors_p1;
+        unsigned devs_in_group = ios->layout->group_width * mirrors_p1;
         unsigned dev = si->dev;
-        unsigned comp = 0;
-        unsigned stripes = 0;
-        unsigned cur_pg = 0;
+        unsigned first_dev = dev - (dev % devs_in_group);
+        unsigned comp = first_comp + (dev - first_dev);
+        unsigned max_comp = ios->numdevs ? ios->numdevs - mirrors_p1 : 0;
+        unsigned cur_pg = ios->pages_consumed;
         int ret = 0;
 
         while (length) {
@@ -377,10 +423,11 @@ static int _prepare_pages(struct exofs_io_state *ios,
                                 cur_len = stripe_unit;
                         }
 
-                        stripes++;
+                        if (max_comp < comp)
+                                max_comp = comp;
 
                         dev += mirrors_p1;
-                        dev %= ios->layout->s_numdevs;
+                        dev = (dev % devs_in_group) + first_dev;
                 } else {
                         cur_len = stripe_unit;
                 }
@@ -393,18 +440,24 @@ static int _prepare_pages(struct exofs_io_state *ios,
                         goto out;
 
                 comp += mirrors_p1;
-                comp %= ios->layout->s_numdevs;
+                comp = (comp % devs_in_group) + first_comp;
 
                 length -= cur_len;
         }
 out:
-        ios->numdevs = stripes * mirrors_p1;
+        ios->numdevs = max_comp + mirrors_p1;
+        ios->pages_consumed = cur_pg;
         return ret;
 }
 
 static int _prepare_for_striping(struct exofs_io_state *ios)
 {
+        u64 length = ios->length;
         struct _striping_info si;
+        unsigned devs_in_group = ios->layout->group_width *
+                                 ios->layout->mirrors_p1;
+        unsigned first_comp = 0;
+        int ret = 0;
 
         _calc_stripe_info(ios, ios->offset, &si);
 
@@ -424,7 +477,31 @@ static int _prepare_for_striping(struct exofs_io_state *ios)
                 return 0;
         }
 
-        return _prepare_pages(ios, &si);
+        while (length) {
+                if (length < si.group_length)
+                        si.group_length = length;
+
+                ret = _prepare_one_group(ios, si.group_length, &si, first_comp);
+                if (unlikely(ret))
+                        goto out;
+
+                length -= si.group_length;
+
+                si.group_length = si.total_group_length;
+                si.unit_off = 0;
+                ++si.Major;
+                si.obj_offset = si.Major * ios->layout->stripe_unit *
+                                                ios->layout->group_depth;
+
+                si.dev = (si.dev - (si.dev % devs_in_group)) + devs_in_group;
+                si.dev %= ios->layout->s_numdevs;
+
+                first_comp += devs_in_group;
+                first_comp %= ios->layout->s_numdevs;
+        }
+
+out:
+        return ret;
 }
 
 int exofs_sbi_create(struct exofs_io_state *ios)
@@ -482,6 +559,9 @@ static int _sbi_write_mirror(struct exofs_io_state *ios, int cur_comp)
         unsigned last_comp = cur_comp + ios->layout->mirrors_p1;
         int ret = 0;
 
+        if (ios->pages && !master_dev->length)
+                return 0; /* Just an empty slot */
+
         for (; cur_comp < last_comp; ++cur_comp, ++dev) {
                 struct exofs_per_dev_state *per_dev = &ios->per_dev[cur_comp];
                 struct osd_request *or;
@@ -580,6 +660,9 @@ static int _sbi_read_mirror(struct exofs_io_state *ios, unsigned cur_comp)
         struct exofs_per_dev_state *per_dev = &ios->per_dev[cur_comp];
         unsigned first_dev = (unsigned)ios->obj.id;
 
+        if (ios->pages && !per_dev->length)
+                return 0; /* Just an empty slot */
+
         first_dev = per_dev->dev + first_dev % ios->layout->mirrors_p1;
         or = osd_start_request(exofs_ios_od(ios, first_dev), GFP_KERNEL);
         if (unlikely(!or)) {