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, 64 insertions, 0 deletions

diff --git a/fs/exofs/ore_raid.h b/fs/exofs/ore_raid.h
new file mode 100644
index 0000000..c21080b
--- /dev/null
+++ b/fs/exofs/ore_raid.h
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) from 2011
+ * Boaz Harrosh <bharrosh@panasas.com>
+ *
+ * This file is part of the objects raid engine (ore).
+ *
+ * It is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with "ore". If not, write to the Free Software Foundation, Inc:
+ *	"Free Software Foundation <info@fsf.org>"
+ */
+
+#include <scsi/osd_ore.h>
+
+#define ORE_ERR(fmt, a...) printk(KERN_ERR "ore: " fmt, ##a)
+
+#ifdef CONFIG_EXOFS_DEBUG
+#define ORE_DBGMSG(fmt, a...) \
+	printk(KERN_NOTICE "ore @%s:%d: " fmt, __func__, __LINE__, ##a)
+#else
+#define ORE_DBGMSG(fmt, a...) \
+	do { if (0) printk(fmt, ##a); } while (0)
+#endif
+
+/* u64 has problems with printk this will cast it to unsigned long long */
+#define _LLU(x) (unsigned long long)(x)
+
+#define ORE_DBGMSG2(M...) do {} while (0)
+/* #define ORE_DBGMSG2 ORE_DBGMSG */
+
+/* Calculate the component order in a stripe. eg the logical data unit
+ * address within the stripe of @dev given the @par_dev of this stripe.
+ */
+static inline unsigned _dev_order(unsigned devs_in_group, unsigned mirrors_p1,
+				  unsigned par_dev, unsigned dev)
+{
+	unsigned first_dev = dev - dev % devs_in_group;
+
+	dev -= first_dev;
+	par_dev -= first_dev;
+
+	if (devs_in_group == par_dev) /* The raid 0 case */
+		return dev / mirrors_p1;
+	/* raid4/5/6 case */
+	return ((devs_in_group + dev - par_dev - mirrors_p1) % devs_in_group) /
+	       mirrors_p1;
+}
+
+/* ios_raid.c stuff needed by ios.c */
+int _ore_post_alloc_raid_stuff(struct ore_io_state *ios);
+void _ore_free_raid_stuff(struct ore_io_state *ios);
+
+void _ore_add_sg_seg(struct ore_per_dev_state *per_dev, unsigned cur_len,
+		 bool not_last);
+int _ore_add_parity_unit(struct ore_io_state *ios, struct ore_striping_info *si,
+		     struct ore_per_dev_state *per_dev, unsigned cur_len);
+
+/* ios.c stuff needed by ios_raid.c */
+int _ore_add_stripe_unit(struct ore_io_state *ios,  unsigned *cur_pg,
+		unsigned pgbase, struct page **pages,
+		struct ore_per_dev_state *per_dev, int cur_len);