ore: RAID5 read

This patch introduces the first stage of RAID5 support
mainly the skip-over-raid-units when reading. For
writes it inserts BLANK units, into where XOR blocks
should be calculated and written to.

It introduces the new "general raid maths", and the main
additional parameters and components needed for raid5.

Since at this stage it could corrupt future version that
actually do support raid5. The enablement of raid5
mounting and setting of parity-count > 0 is disabled. So
the raid5 code will never be used. Mounting of raid5 is
only enabled later once the basic XOR write is also in.
But if the patch "enable RAID5" is applied this code has
been tested to be able to properly read raid5 volumes
and is according to standard.

Also it has been tested that the new maths still properly
supports RAID0 and grouping code just as before.
(BTW: I have found more bugs in the pnfs-obj RAID math
 fixed here)

The ore.c file is getting too big, so new ore_raid.[hc]
files are added that will include the special raid stuff
that are not used in striping and mirrors. In future write
support these will get bigger.
When adding the ore_raid.c to Kbuild file I was forced to
rename ore.ko to libore.ko. Is it possible to keep source
file, say ore.c and module file ore.ko the same even if there
are multiple files inside ore.ko?

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

1 files changed, 18 insertions, 3 deletions

diff --git a/include/scsi/osd_ore.h b/include/scsi/osd_ore.h
index a8e39d14f82b..43821c18cd3f 100644
--- a/include/scsi/osd_ore.h
+++ b/include/scsi/osd_ore.h
@@ -40,6 +40,7 @@ struct ore_layout {
         unsigned mirrors_p1;
 
         unsigned group_width;
+        unsigned parity;
         u64      group_depth;
         unsigned group_count;
 
@@ -89,11 +90,16 @@ static inline void ore_comp_set_dev(
 }
 
 struct ore_striping_info {
+        u64 offset;
         u64 obj_offset;
-        u64 group_length;
+        u64 length;
+        u64 first_stripe_start; /* only used in raid writes */
         u64 M; /* for truncate */
+        unsigned bytes_in_stripe;
         unsigned dev;
+        unsigned par_dev;
         unsigned unit_off;
+        unsigned cur_comp;
 };
 
 struct ore_io_state;
@@ -127,6 +133,13 @@ struct ore_io_state {
 
         bool                    reading;
 
+        /* House keeping of Parity pages */
+        bool                    extra_part_alloc;
+        struct page             **parity_pages;
+        unsigned                max_par_pages;
+        unsigned                cur_par_page;
+        unsigned                sgs_per_dev;
+
         /* Variable array of size numdevs */
         unsigned numdevs;
         struct ore_per_dev_state {
@@ -134,7 +147,10 @@ struct ore_io_state {
                 struct bio *bio;
                 loff_t offset;
                 unsigned length;
+                unsigned last_sgs_total;
                 unsigned dev;
+                struct osd_sg_entry *sglist;
+                unsigned cur_sg;
         } per_dev[];
 };
 
@@ -147,8 +163,7 @@ static inline unsigned ore_io_state_size(unsigned numdevs)
 /* ore.c */
 int ore_verify_layout(unsigned total_comps, struct ore_layout *layout);
 void ore_calc_stripe_info(struct ore_layout *layout, u64 file_offset,
-                          struct ore_striping_info *si);
-
+                          u64 length, struct ore_striping_info *si);
 int ore_get_rw_state(struct ore_layout *layout, struct ore_components *comps,
                      bool is_reading, u64 offset, u64 length,
                      struct ore_io_state **ios);