Commit graph

227 commits

Author SHA1 Message Date
NeilBrown
48606a9f2f md/raid5: correctly update sync_completed when we reach max_resync
At the end of reshape_request we update cyrr_resync_completed
if we are about to pause due to reaching resync_max.
However we update it to the wrong value.  We need to add the
"reshape_sectors" that have just been reshaped.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 09:14:12 +10:00
Dan Williams
7a3ab90894 md/raid5: add missing call to schedule() after prepare_to_wait()
In the unlikely event that reshape progresses past the current request
while it is waiting for a stripe we need to schedule() before retrying
for 2 reasons:
1/ Prevent list corruption from duplicated list_add() calls without
   intervening list_del().
2/ Give the reshape code a chance to make some progress to resolve the
   conflict.

Cc: <stable@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:50:18 +10:00
Andre Noll
8c6ac868b1 md: Push down reconstruction log message to personality code.
Currently, the md layer checks in analyze_sbs() if the raid level
supports reconstruction (mddev->level >= 1) and if reconstruction is
in progress (mddev->recovery_cp != MaxSector).

Move that printk into the personality code of those raid levels that
care (levels 1, 4, 5, 6, 10).

Signed-off-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:48:06 +10:00
NeilBrown
50ac168a6e md: merge reconfig and check_reshape methods.
The difference between these two methods is artificial.
Both check that a pending reshape is valid, and perform any
aspect of it that can be done immediately.
'reconfig' handles chunk size and layout.
'check_reshape' handles raid_disks.

So make them just one method.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:47:55 +10:00
NeilBrown
597a711b69 md: remove unnecessary arguments from ->reconfig method.
Passing the new layout and chunksize as args is not necessary as
the mddev has fields for new_check and new_layout.

This is preparation for combining the check_reshape and reconfig
methods

Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:47:42 +10:00
NeilBrown
01ee22b496 md: raid5: check stripe cache is large enough in start_reshape
In reshape cases that do not change the number of devices,
start_reshape is called without first calling check_reshape.

Currently, the check that the stripe_cache is large enough is
only done in check_reshape.  It should be in start_reshape too.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:47:20 +10:00
Andre Noll
cdc2ae6d6a md: fix some comments.
1/ Raid5 has learned to take over also raid4 and raid6 arrays.
2/ new_chunk in mdp_superblock_1 is in sectors, not bytes.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:46:47 +10:00
Andre Noll
0ba459d262 md/raid5: Use is_power_of_2() in raid5_reconfig()/raid6_reconfig().
Signed-off-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:46:10 +10:00
Andre Noll
09c9e5fa1b md: convert conf->chunk_size and conf->prev_chunk to sectors.
This kills some more shifts.

Signed-off-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:45:55 +10:00
Andre Noll
664e7c413f md: Convert mddev->new_chunk to sectors.
A straight-forward conversion which gets rid of some
multiplications/divisions/shifts. The patch also introduces a couple
of new ones, most of which are due to conf->chunk_size still being
represented in bytes. This will be cleaned up in subsequent patches.

Signed-off-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:45:27 +10:00
Andre Noll
9d8f036362 md: Make mddev->chunk_size sector-based.
This patch renames the chunk_size field to chunk_sectors with the
implied change of semantics.  Since

	is_power_of_2(chunk_size) = is_power_of_2(chunk_sectors << 9)
				  = is_power_of_2(chunk_sectors)

these bits don't need an adjustment for the shift.

Signed-off-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-18 08:45:01 +10:00
raz ben yehuda
740da44918 md: raid5: chunk size check in setup_conf
have raid5 check chunk size in run/reshape method instead of in md

Signed-off-by: raziebe@gmail.com
Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-16 17:01:36 +10:00
NeilBrown
070ec55d07 md: remove mddev_to_conf "helper" macro
Having a macro just to cast a void* isn't really helpful.
I would must rather see that we are simply de-referencing ->private,
than have to know what the macro does.

So open code the macro everywhere and remove the pointless cast.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-16 16:54:21 +10:00
Linus Torvalds
c9059598ea Merge branch 'for-2.6.31' of git://git.kernel.dk/linux-2.6-block
* 'for-2.6.31' of git://git.kernel.dk/linux-2.6-block: (153 commits)
  block: add request clone interface (v2)
  floppy: fix hibernation
  ramdisk: remove long-deprecated "ramdisk=" boot-time parameter
  fs/bio.c: add missing __user annotation
  block: prevent possible io_context->refcount overflow
  Add serial number support for virtio_blk, V4a
  block: Add missing bounce_pfn stacking and fix comments
  Revert "block: Fix bounce limit setting in DM"
  cciss: decode unit attention in SCSI error handling code
  cciss: Remove no longer needed sendcmd reject processing code
  cciss: change SCSI error handling routines to work with interrupts enabled.
  cciss: separate error processing and command retrying code in sendcmd_withirq_core()
  cciss: factor out fix target status processing code from sendcmd functions
  cciss: simplify interface of sendcmd() and sendcmd_withirq()
  cciss: factor out core of sendcmd_withirq() for use by SCSI error handling code
  cciss: Use schedule_timeout_uninterruptible in SCSI error handling code
  block: needs to set the residual length of a bidi request
  Revert "block: implement blkdev_readpages"
  block: Fix bounce limit setting in DM
  Removed reference to non-existing file Documentation/PCI/PCI-DMA-mapping.txt
  ...

Manually fix conflicts with tracing updates in:
	block/blk-sysfs.c
	drivers/ide/ide-atapi.c
	drivers/ide/ide-cd.c
	drivers/ide/ide-floppy.c
	drivers/ide/ide-tape.c
	include/trace/events/block.h
	kernel/trace/blktrace.c
2009-06-11 11:10:35 -07:00
NeilBrown
0e6e0271a2 md/raid5: fix bug in reshape code when chunk_size decreases.
Now that we support changing the chunksize, we calculate
"reshape_sectors" to be the max of number of sectors in old
and new chunk size.
However there is one please where we still use 'chunksize'
rather than 'reshape_sectors'.
This causes a reshape that reduces the size of chunks to freeze.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-09 16:32:22 +10:00
NeilBrown
a8c906ca3f md/raid5 - avoid deadlocks in get_active_stripe during reshape
md has functionality to 'quiesce' and array so that all pending
IO completed and no new IO starts.  This is used to achieve a
stable state before making internal changes.

Currently this quiescing applies equally to normal IO, resync
IO, and reshape IO.
However there is a problem with applying it to reshape IO.
Reshape can have multiple 'stripe_heads' that must be active together.
If the quiesce come between allocating the first and the last of
such a collection, then we deadlock, as the last will not be allocated
until the quiesce is lifted, the quiesce will not be lifted until the
first (which has been allocated) gets used, and that first cannot be
used until the last is allocated.

It is not necessary to inhibit reshape IO when a quiesce is
requested.  Those places in the code that require a full quiesce will
ensure the reshape thread is not running at all.

So allow reshape requests to get access to new stripe_heads without
being blocked by a 'quiesce'.

This only affects in-place reshapes (i.e. where the array does not
grow or shrink) and these are only newly supported.  So this patch is
not needed in earlier kernels.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-09 14:39:59 +10:00
NeilBrown
f001a70cdc md/raid5: use conf->raid_disks in preference to mddev->raid_disk
mddev->raid_disks can be changed and any time by a request from
user-space.  It is a suggestion as to what number of raid_disks is
desired.

conf->raid_disks can only be changed by the raid5 module with suitable
locks in place.  It is a statement as to the current number of
raid_disks.

There are two places where the latter should be used, but the former
is used.  This can lead to a crash when reshaping an array.

This patch changes to mddev-> to conf->

Signed-off-by: NeilBrown <neilb@suse.de>
2009-06-09 14:30:31 +10:00
NeilBrown
ed37d83e6a md: raid5: change incorrect usage of 'min' macro to 'min_t'
A recent patch to raid5.c use min on an int and a sector_t.
This isn't allowed.
So change it to min_t(sector_t,x,y).

Signed-off-by: NeilBrown <neilb@suse.de>
2009-05-27 21:39:05 +10:00
NeilBrown
848b318236 md: raid5: avoid sector values going negative when testing reshape progress.
As sector_t in unsigned, we cannot afford to let 'safepos' etc go
negative.
So replace
   a -= b;
by
   a -= min(b,a);

Signed-off-by: NeilBrown <neilb@suse.de>
2009-05-26 12:41:08 +10:00
Martin K. Petersen
ae03bf639a block: Use accessor functions for queue limits
Convert all external users of queue limits to using wrapper functions
instead of poking the request queue variables directly.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-22 23:22:54 +02:00
NeilBrown
c03f6a1969 md: update sync_completed and reshape_position even more often.
There are circumstances when a user-space process might need to
"oversee" a resync/reshape process.  For example when doing an
in-place reshape of a raid5, it is prudent to take a backup of each
section before reshaping it as this is the only way to provide
safety against an unplanned shutdown (i.e. crash/power failure).

The sync_max sysfs value can be used to stop the resync from
advancing beyond a particular point.
So user-space can:
  suspend IO to the first section and back it up
  set 'sync_max' to the end of the section
  wait for 'sync_completed' to reach that point
  resume IO on the first section and move on to the next section.

However this process requires the kernel and user-space to run in
lock-step which could introduce unnecessary delays.

It would be better if a 'double buffered' approach could be used with
userspace and kernel space working on different sections with the
'next' section always ready when the 'current' section is finished.

One problem with implementing this is that sync_completed is only
guaranteed to be updated when the sync process reaches sync_max.
(it is updated on a time basis at other times, but it is hard to rely
on that).  This defeats some of the double buffering.

With this patch, sync_completed (and reshape_position) get updated as
the current position approaches sync_max, so there is room for
userspace to advance sync_max early without losing updates.

To be precise, sync_completed is updated when the current sync
position reaches half way between the current value of sync_completed
and the value of sync_max.  This will usually be a good time for user
space to update sync_max.

If sync_max does not get updated, the updates to sync_completed
(together with associated metadata updates) will occur at an
exponentially increasing frequency which will get unreasonably fast
(one update every page) immediately before the process hits sync_max
and stops.  So the update rate will be unreasonably fast only for an
insignificant period of time.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-04-17 11:06:30 +10:00
NeilBrown
acb180b0e3 md: improve usefulness and accuracy of sysfs file md/sync_completed.
The sync_completed file reports how much of a resync (or recovery or
reshape) has been completed.
However due to the possibility of out-of-order completion of writes,
it is not certain to be accurate.

We have an internal value - mddev->curr_resync_completed - which is an
accurate value (though it might not always be quite so uptodate).

So:
 - make curr_resync_completed be uptodate a little more often,
   particularly when raid5 reshape updates status in the metadata
 - report curr_resync_completed in the sysfs file
 - allow poll/select to report all updates to md/sync_completed.

This makes sync_completed completed usable by any external metadata
handler that wants to record this status information in its metadata.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-04-14 16:28:34 +10:00
NeilBrown
c8f517c444 md/raid5 revise rules for when to update metadata during reshape
We currently update the metadata :
 1/ every 3Megabytes
 2/ When the place we will write new-layout data to is recorded in
    the metadata as still containing old-layout data.

Rule one exists to avoid having to re-do too much reshaping in the
face of a crash/restart.  So it should really be time based rather
than size based.  So change it to "every 10 seconds".

Rule two turns out to be too harsh when restriping an array
'in-place', as in that case the metadata much be updates for every
stripe.
For the in-place update, it can only possibly be safe from a crash if
some user-space program data a backup of every e.g. few hundred
stripes before allowing them to be reshaped.  In that case, the
constant metadata update is pointless.
So only update the metadata if the new metadata will report that the
end of the 'old-layout' data is beyond where we are currently
writing 'new-layout' data.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:28:40 +11:00
NeilBrown
b0f9ec047b md/raid5: minor code cleanups in make_request.
... and to be certain the that make_request doesn't wait forever,
add a 'wake_up' when ->reshape_progress has been set to MaxSector

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:27:18 +11:00
NeilBrown
2cffc4a01d md: remove CONFIG_MD_RAID_RESHAPE config option.
This was only needed when the code was experimental.  Most of it
is well tested now, so the option is no longer useful.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:27:05 +11:00
NeilBrown
ab69ae12ce md/raid5: be more careful about write ordering when reshaping.
When we are reshaping an array, it is very important that we read
the data from a particular sector offset before writing new data
at that offset.

In most cases when growing or shrinking an array we read long before
we even consider writing.  But when restriping an array without
changing it size, there is a small possibility that we might have
some data to available write before the read has happened at the same
location.  This would require some stripes to be in cache already.

To guard against this small possibility, we check, before writing,
that the 'old' stripe at the same location is not in the process of
being read.  And we ensure that we mark all 'source' stripes as such
before allowing new 'destination' stripes to proceed.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:26:47 +11:00
NeilBrown
88ce4930e2 md/raid5: allow layout and chunksize to be changed on active array.
If an array has 3 or more devices, we allow the chunksize or layout
to be changed and when a reshape starts, we use these as the 'new'
values.


Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:24:23 +11:00
NeilBrown
7a66138107 md/raid5: reshape using largest of old and new chunk size
This ensures that even when old and new stripes are overlapping,
we will try to read all of the old before having to write any
of the new.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:21:40 +11:00
NeilBrown
e183eaedd5 md/raid5: prepare for allowing reshape to change layout
Add prev_algo to raid5_conf_t along the same lines as prev_chunk
and previous_raid_disks.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:20:22 +11:00
NeilBrown
784052ecc6 md/raid5: prepare for allowing reshape to change chunksize.
Add "prev_chunk" to raid5_conf_t, similar to "previous_raid_disks", to
remember what the chunk size was before the reshape that is currently
underway.

This seems like duplication with "chunk_size" and "new_chunk" in
mddev_t, and to some extent it is, but there are differences.
The values in mddev_t are always defined and often the same.
The prev* values are only defined if a reshape is underway.

Also (and more significantly) the raid5_conf_t values will be changed
at the same time (inside an appropriate lock) that the reshape is
started by setting reshape_position.  In contrast, the new_chunk value
is set when the sysfs file is written which could be well before the
reshape starts.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:19:07 +11:00
NeilBrown
86b42c713b md/raid5: clearly differentiate 'before' and 'after' stripes during reshape.
During a raid5 reshape, we have some stripes in the cache that are
'before' the reshape (and are still to be processed) and some that are
'after'.  They are currently differentiated by having different
->disks values as the only reshape current supported involves changing
the number of disks.

However we will soon support reshapes that do not change the number
of disks (chunk parity or chunk size).  So make the difference more
explicit with a 'generation' number.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:19:03 +11:00
NeilBrown
ec32a2bd35 md: allow number of drives in raid5 to be reduced
When reshaping a raid5 to have fewer devices, we work from the end of
the array to the beginning.
md_do_sync gives addresses to sync_request that go from the beginning
to the end.  So largely ignore them use the internal state variable
"reshape_progress" to keep track of what to do next.

Never allow the size to be reduced below the minimum (4 for raid6,
3 otherwise).

We require that the size of the array has already been reduced before
the array is reshaped to a smaller size.  This is because simply
reducing the size is an easily reversible operation, while the reshape
is immediately destructive and so is not reversible for the blocks at
the ends of the devices.
Thus to reshape an array to have fewer devices, you must first write
an appropriately small size to md/array_size.

When reshape finished, we remove any drives that are no longer
needed and fix up ->degraded.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:17:38 +11:00
NeilBrown
fef9c61fdf md/raid5: change reshape-progress measurement to cope with reshaping backwards.
When reducing the number of devices in a raid4/5/6, the reshape
process has to start at the end of the array and work down to the
beginning.  So we need to handle expand_progress and expand_lo
differently.

This patch renames "expand_progress" and "expand_lo" to avoid the
implication that anything is getting bigger (expand->reshape) and
every place they are used, we make sure that they are used the right
way depending on whether delta_disks is positive or negative.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:16:46 +11:00
NeilBrown
cea9c22800 md: add explicit method to signal the end of a reshape.
Currently raid5 (the only module that supports restriping)
notices that the reshape has finished be sync_request being
given a large value, and handles any cleanup them.

This patch changes it so md_check_recovery calls into an
explicit finish_reshape method as well.

The clean-up from sync_request can do things that need to be
done promptly, typically things local to the raid5_conf_t
structure.

The "finish_reshape" method is called under the mddev_lock
so it can do things involving reconfiguring the device.

This allows us to get rid of md_set_array_sectors_locked, which
would have caused a deadlock if you tried to stop and array
while a reshape was happening.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:15:05 +11:00
NeilBrown
7ec0547838 md/raid5: enhance raid5_size to work correctly with negative delta_disks
This is the first of four patches which combine to allow md/raid5 to
reduce the number of devices in the array by restriping the data over
a subset of the devices.

If the number of disks in a raid4/5/6 is being reduced, then the
default size must be based on the new number, not the old number
of devices.
In general, it should be based on the smaller of new and old.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:10:36 +11:00
NeilBrown
34e04e87fb md/raid5: drop qd_idx from r6_state
We now have this value in stripe_head so we don't need to duplicate
it.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:10:16 +11:00
Dan Williams
f701d589aa md/raid6: move raid6 data processing to raid6_pq.ko
Move the raid6 data processing routines into a standalone module
(raid6_pq) to prepare them to be called from async_tx wrappers and other
non-md drivers/modules.  This precludes a circular dependency of raid456
needing the async modules for data processing while those modules in
turn depend on raid456 for the base level synchronous raid6 routines.

To support this move:
1/ The exportable definitions in raid6.h move to include/linux/raid/pq.h
2/ The raid6_call, recovery calls, and table symbols are exported
3/ Extra #ifdef __KERNEL__ statements to enable the userspace raid6test to
   compile

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:09:39 +11:00
Andre Noll
18b0033491 md: raid5 run(): Fix max_degraded for raid level 4.
raid4 allows only one failed disk.

Signed-off-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 15:00:56 +11:00
Dan Williams
b522adcde9 md: 'array_size' sysfs attribute
Allow userspace to set the size of the array according to the following
semantics:

1/ size must be <= to the size returned by mddev->pers->size(mddev, 0, 0)
   a) If size is set before the array is running, do_md_run will fail
      if size is greater than the default size
   b) A reshape attempt that reduces the default size to less than the set
      array size should be blocked
2/ once userspace sets the size the kernel will not change it
3/ writing 'default' to this attribute returns control of the size to the
   kernel and reverts to the size reported by the personality

Also, convert locations that need to know the default size from directly
reading ->array_sectors to <pers>_size.  Resync/reshape operations
always follow the default size.

Finally, fixup other locations that read a number of 1k-blocks from
userspace to use strict_blocks_to_sectors() which checks for unsigned
long long to sector_t overflow and blocks to sectors overflow.

Reviewed-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-03-31 15:00:31 +11:00
Dan Williams
1f403624bd md: centralize ->array_sectors modifications
Get personalities out of the business of directly modifying
->array_sectors.  Lays groundwork to introduce policy on when
->array_sectors can be modified.

Reviewed-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-03-31 14:59:03 +11:00
Dan Williams
80c3a6ce4b md: add 'size' as a personality method
In preparation for giving userspace control over ->array_sectors we need
to be able to retrieve the 'default' size, and the 'anticipated' size
when a reshape is requested.  For personalities that do not reshape emit
a warning if anything but the default size is requested.

In the raid5 case we need to update ->previous_raid_disks to make the
new 'default' size available.

Reviewed-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2009-03-31 14:57:49 +11:00
NeilBrown
fc9739c6d6 md: add takeover support for converting raid6 back into raid5
If a raid6 is still in the layout that comes from converting raid5
into a raid6. this will allow us to convert it back again.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 14:57:20 +11:00
NeilBrown
e9d4758f6e md: add takeover support for raid4 -> raid5 conversion.
Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 14:57:09 +11:00
NeilBrown
b354603527 md/raid5: allow layout/chunksize to be changed on an active 2-drive raid5.
2-drive raid5's aren't very interesting.  But if you are converting
a raid1 into a raid5, you will at least temporarily have one.  And
that it a good time to set the layout/chunksize for the new RAID5
if you aren't happy with the defaults.

layout and chunksize don't actually affect the placement of data
on a 2-drive raid5, so we just do some internal book-keeping.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 14:56:41 +11:00
NeilBrown
d562b0c431 md: add ->takeover method for raid5 to be able to take over raid1
The RAID1 must have two drives and be a suitable size to
be a multiple of a chunksize that isn't too small.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 14:39:39 +11:00
NeilBrown
245f46c2c2 md: add ->takeover method to support changing the personality managing an array
Implement this for RAID6 to be able to 'takeover' a RAID5 array.  The
new RAID6 will use a layout which places Q on the last device, and
that device will be missing.
If there are any available spares, one will immediately have Q
recovered onto it.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 14:39:39 +11:00
NeilBrown
e0cf8f045b md: md_unregister_thread should cope with being passed NULL
Mostly md_unregister_thread is only called when we know that the
thread is NULL, but sometimes we need to check first.  It is safer
to put the check inside md_unregister_thread itself.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 14:39:39 +11:00
NeilBrown
91adb56473 md/raid5: refactor raid5 "run"
.. so that the code to create the private data structures is separate.
This will help with future code to change the level of an active
array.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 14:39:39 +11:00
NeilBrown
67cc2b8165 md/raid5: finish support for DDF/raid6
DDF requires RAID6 calculations over different devices in a different
order.
For md/raid6, we calculate over just the data devices, starting
immediately after the 'Q' block.
For ddf/raid6 we calculate over all devices, using zeros in place of
the P and Q blocks.

This requires unfortunately complex loops...

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 14:39:38 +11:00
NeilBrown
99c0fb5f92 md/raid5: Add support for new layouts for raid5 and raid6.
DDF uses different layouts for P and Q blocks than current md/raid6
so add those that are missing.
Also add support for RAID6 layouts that are identical to various
raid5 layouts with the simple addition of one device to hold all of
the 'Q' blocks.
Finally add 'raid5' layouts to match raid4.
These last to will allow online level conversion.

Note that this does not provide correct support for DDF/raid6 yet
as the order in which data blocks are summed to produce the Q block
is significant and different between current md code and DDF
requirements.

Signed-off-by: NeilBrown <neilb@suse.de>
2009-03-31 14:39:38 +11:00