Merge tag 'md-3.9' of git://neil.brown.name/md

Pull md updates from NeilBrown:
 "Mostly little bugfixes.

  Only "feature" is a new RAID10 layout which slightly improves the
  number of sets of devices that can concurrently fail, without data
  loss."

* tag 'md-3.9' of git://neil.brown.name/md:
  md: expedite metadata update when switching  read-auto -> active
  md: remove CONFIG_MULTICORE_RAID456
  md/raid1,raid10: fix deadlock with freeze_array()
  md/raid0: improve error message when converting RAID4-with-spares to RAID0
  md: raid0: fix error return from create_stripe_zones.
  md: fix two bugs when attempting to resize RAID0 array.
  DM RAID: Add support for MD's RAID10 "far" and "offset" algorithms
  MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 2)
  MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 1)
  MD RAID10: Minor non-functional code changes
  md: raid1,10: Handle REQ_WRITE_SAME flag in write bios
  md: protect against crash upon fsync on ro array

1 files changed, 37 insertions, 7 deletions

diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt
index 56fb62b09fc5..b428556197c9 100644
--- a/Documentation/device-mapper/dm-raid.txt
+++ b/Documentation/device-mapper/dm-raid.txt
@@ -30,6 +30,7 @@ The target is named "raid" and it accepts the following parameters:
   raid10        Various RAID10 inspired algorithms chosen by additional params
                 - RAID10: Striped Mirrors (aka 'Striping on top of mirrors')
                 - RAID1E: Integrated Adjacent Stripe Mirroring
+                - RAID1E: Integrated Offset Stripe Mirroring
                 -  and other similar RAID10 variants
 
   Reference: Chapter 4 of
@@ -64,15 +65,15 @@ The target is named "raid" and it accepts the following parameters:
                 synchronisation state for each region.
 
         [raid10_copies   <# copies>]
-        [raid10_format   near]
+        [raid10_format   <near|far|offset>]
                 These two options are used to alter the default layout of
                 a RAID10 configuration.  The number of copies is can be
-                specified, but the default is 2.  There are other variations
-                to how the copies are laid down - the default and only current
-                option is "near".  Near copies are what most people think of
-                with respect to mirroring.  If these options are left
-                unspecified, or 'raid10_copies 2' and/or 'raid10_format near'
-                are given, then the layouts for 2, 3 and 4 devices are:
+                specified, but the default is 2.  There are also three
+                variations to how the copies are laid down - the default
+                is "near".  Near copies are what most people think of with
+                respect to mirroring.  If these options are left unspecified,
+                or 'raid10_copies 2' and/or 'raid10_format near' are given,
+                then the layouts for 2, 3 and 4 devices are:
                 2 drives         3 drives          4 drives
                 --------         ----------        --------------
                 A1  A1           A1  A1  A2        A1  A1  A2  A2
@@ -85,6 +86,33 @@ The target is named "raid" and it accepts the following parameters:
                 3-device layout is what might be called a 'RAID1E - Integrated
                 Adjacent Stripe Mirroring'.
 
+                If 'raid10_copies 2' and 'raid10_format far', then the layouts
+                for 2, 3 and 4 devices are:
+                2 drives             3 drives             4 drives
+                --------             --------------       --------------------
+                A1  A2               A1   A2   A3         A1   A2   A3   A4
+                A3  A4               A4   A5   A6         A5   A6   A7   A8
+                A5  A6               A7   A8   A9         A9   A10  A11  A12
+                ..  ..               ..   ..   ..         ..   ..   ..   ..
+                A2  A1               A3   A1   A2         A2   A1   A4   A3
+                A4  A3               A6   A4   A5         A6   A5   A8   A7
+                A6  A5               A9   A7   A8         A10  A9   A12  A11
+                ..  ..               ..   ..   ..         ..   ..   ..   ..
+
+                If 'raid10_copies 2' and 'raid10_format offset', then the
+                layouts for 2, 3 and 4 devices are:
+                2 drives       3 drives           4 drives
+                --------       ------------       -----------------
+                A1  A2         A1  A2  A3         A1  A2  A3  A4
+                A2  A1         A3  A1  A2         A2  A1  A4  A3
+                A3  A4         A4  A5  A6         A5  A6  A7  A8
+                A4  A3         A6  A4  A5         A6  A5  A8  A7
+                A5  A6         A7  A8  A9         A9  A10 A11 A12
+                A6  A5         A9  A7  A8         A10 A9  A12 A11
+                ..  ..         ..  ..  ..         ..  ..  ..  ..
+                Here we see layouts closely akin to 'RAID1E - Integrated
+                Offset Stripe Mirroring'.
+
 <#raid_devs>: The number of devices composing the array.
         Each device consists of two entries.  The first is the device
         containing the metadata (if any); the second is the one containing the
@@ -142,3 +170,5 @@ Version History
 1.3.0   Added support for RAID 10
 1.3.1   Allow device replacement/rebuild for RAID 10
 1.3.2   Fix/improve redundancy checking for RAID10
+1.4.0   Non-functional change.  Removes arg from mapping function.
+1.4.1   Add RAID10 "far" and "offset" algorithm support.