Optimize RAID6 recovery functions to take advantage of
the 256-bit YMM integer instructions introduced in AVX2.
The patch was tested and benchmarked before submission.
However hardware is not yet released so benchmark numbers
cannot be reported.
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Jim Kukunas <james.t.kukunas@linux.intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Add SSSE3 optimized recovery functions, as well as a system
for selecting the most appropriate recovery functions to use.
Originally-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Jim Kukunas <james.t.kukunas@linux.intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
When reshaping we can avoid costly intermediate backup by
changing the 'start' address of the array on the device
(if there is enough room).
So as a first step, allow such a change to be requested
through sysfs, and recorded in v1.x metadata.
(As we didn't previous check that all 'pad' fields were zero,
we need a new FEATURE flag for this.
A (belatedly) check that all remaining 'pad' fields are
zero to avoid a repeat of this)
The new data offset must be requested separately for each device.
This allows each to have a different change in the data offset.
This is not likely to be used often but as data_offset can be
set per-device, new_data_offset should be too.
This patch also removes the 'acknowledged' arg to rdev_set_badblocks as
it is never used and never will be. At the same time we add a new
arg ('in_new') which is currently always zero but will be used more
soon.
When a reshape finishes we will need to update the data_offset
and rdev->sectors. So provide an exported function to do that.
Signed-off-by: NeilBrown <neilb@suse.de>
Currently a reshape operation always progresses from the start
of the array to the end unless the number of devices is being
reduced, in which case it progressed in the opposite direction.
To reverse a partial reshape which changes the number of devices
you can stop the array and re-assemble with the raid-disks numbers
reversed and it will undo.
However for a reshape that does not change the number of devices
it is not possible to reverse the reshape in the middle - you have to
wait until it completes.
So add a 'reshape_direction' attribute with is either 'forwards' or
'backwards' and can be explicitly set when delta_disks is zero.
This will become more important when we allow the data_offset to
change in a reshape. Then the explicit statement of what direction is
being used will be more useful.
This can be enabled in raid5 trivially as it already supports
reverse reshape and just needs to use a different trigger to request it.
Signed-off-by: NeilBrown <neilb@suse.de>
hot-replace is a feature being added to md which will allow a
device to be replaced without removing it from the array first.
With hot-replace a spare can be activated and recovery can start while
the original device is still in place, thus allowing a transition from
an unreliable device to a reliable device without leaving the array
degraded during the transition. It can also be use when the original
device is still reliable but it not wanted for some reason.
This will eventually be supported in RAID4/5/6 and RAID10.
This patch adds a super-block flag to distinguish the replacement
device. If an old kernel sees this flag it will reject the device.
It also adds two per-device flags which are viewable and settable via
sysfs.
"want_replacement" can be set to request that a device be replaced.
"replacement" is set to show that this device is replacing another
device.
The "rd%d" links in /sys/block/mdXx/md only apply to the original
device, not the replacement. We currently don't make links for the
replacement - there doesn't seem to be a need.
Signed-off-by: NeilBrown <neilb@suse.de>
While using etags to find free_pages(), I stumbled across this debug
definition of free_pages() that is to be used while debugging some raid
code in userspace. The __get_free_pages() allocates the correct size,
but the free_pages() does not match. free_pages(), like
__get_free_pages(), takes an order and not a size.
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Space must have been allocated when array was created.
A feature flag is set when the badblock list is non-empty, to
ensure old kernels don't load and trust the whole device.
We only update the on-disk badblocklist when it has changed.
If the badblocklist (or other metadata) is stored on a bad block, we
don't cope very well.
If metadata has no room for bad block, flag bad-blocks as disabled,
and do the same for 0.90 metadata.
Signed-off-by: NeilBrown <neilb@suse.de>
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>
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>
This makes the includes more explicit, and is preparation for moving
md_k.h to drivers/md/md.h
Remove include/raid/md.h as its only remaining use was to #include
other files.
Signed-off-by: NeilBrown <neilb@suse.de>
The extern function definitions are kernel-internal definitions, so
they belong in md_k.h
The MD_*_VERSION values could reasonably go in a number of places,
but md_u.h seems most reasonable.
This leaves almost nothing in md.h. It will go soon.
Signed-off-by: NeilBrown <neilb@suse.de>
.. as they are part of the user-space interface.
Also move MdpMinorShift into there so we can remove duplication.
Lastly move mdp_major in. It is less obviously part of the user-space
interface, but do_mounts_md.c uses it, and it is acting a bit like
user-space.
Signed-off-by: NeilBrown <neilb@suse.de>
Move the headers with the local structures for the disciplines and
bitmap.h into drivers/md/ so that they are more easily grepable for
hacking and not far away. md.h is left where it is for now as there
are some uses from the outside.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: NeilBrown <neilb@suse.de>
There are two problems with is_mddev_idle.
1/ sync_io is 'atomic_t' and hence 'int'. curr_events and all the
rest are 'long'.
So if sync_io were to wrap on a 64bit host, the value of
curr_events would go very negative suddenly, and take a very
long time to return to positive.
So do all calculations as 'int'. That gives us plenty of precision
for what we need.
2/ To initialise rdev->last_events we simply call is_mddev_idle, on
the assumption that it will make sure that last_events is in a
suitable range. It used to do this, but now it does not.
So now we need to be more explicit about initialisation.
Signed-off-by: NeilBrown <neilb@suse.de>
fix the following 'make headers_check' warning:
usr/include/linux/raid/md_p.h:85: found __[us]{8,16,32,64} type without #include <linux/types.h>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
If a raid1 has only one working drive and it has a sector which
gives an error on read, then an attempt to recover onto a spare will
fail, but as the single remaining drive is not removed from the
array, the recovery will be immediately re-attempted, resulting
in an infinite recovery loop.
So detect this situation and don't retry recovery once an error
on the lone remaining drive is detected.
Allow recovery to be retried once every time a spare is added
in case the problem wasn't actually a media error.
Signed-off-by: NeilBrown <neilb@suse.de>
Using sequential numbers to identify md devices is somewhat artificial.
Using names can be a lot more user-friendly.
Also, creating md devices by opening the device special file is a bit
awkward.
So this patch provides a new option for creating and naming devices.
Writing a name such as "md_home" to
/sys/modules/md_mod/parameters/new_array
will cause an array with that name to be created. It will appear in
/sys/block/ /proc/partitions and /proc/mdstat as 'md_home'.
It will have an arbitrary minor number allocated.
md devices that a created by an open are destroyed on the last
close when the device is inactive.
For named md devices, they will not be destroyed until the array
is explicitly stopped, either with the STOP_ARRAY ioctl or by
writing 'clear' to /sys/block/md_XXXX/md/array_state.
The name of the array must start 'md_' to avoid conflict with
other devices.
Signed-off-by: NeilBrown <neilb@suse.de>
Currently md devices, once created, never disappear until the module
is unloaded. This is essentially because the gendisk holds a
reference to the mddev, and the mddev holds a reference to the
gendisk, this a circular reference.
If we drop the reference from mddev to gendisk, then we need to ensure
that the mddev is destroyed when the gendisk is destroyed. However it
is not possible to hook into the gendisk destruction process to enable
this.
So we drop the reference from the gendisk to the mddev and destroy the
gendisk when the mddev gets destroyed. However this has a
complication.
Between the call
__blkdev_get->get_gendisk->kobj_lookup->md_probe
and the call
__blkdev_get->md_open
there is no obvious way to hold a reference on the mddev any more, so
unless something is done, it will disappear and gendisk will be
destroyed prematurely.
Also, once we decide to destroy the mddev, there will be an unlockable
moment before the gendisk is unlinked (blk_unregister_region) during
which a new reference to the gendisk can be created. We need to
ensure that this reference can not be used. i.e. the ->open must
fail.
So:
1/ in md_probe we set a flag in the mddev (hold_active) which
indicates that the array should be treated as active, even
though there are no references, and no appearance of activity.
This is cleared by md_release when the device is closed if it
is no longer needed.
This ensures that the gendisk will survive between md_probe and
md_open.
2/ In md_open we check if the mddev we expect to open matches
the gendisk that we did open.
If there is a mismatch we return -ERESTARTSYS and modify
__blkdev_get to retry from the top in that case.
In the -ERESTARTSYS sys case we make sure to wait until
the old gendisk (that we succeeded in opening) is really gone so
we loop at most once.
Some udev configurations will always open an md device when it first
appears. If we allow an md device that was just created by an open
to disappear on an immediate close, then this can race with such udev
configurations and result in an infinite loop the device being opened
and closed, then re-open due to the 'ADD' even from the first open,
and then close and so on.
So we make sure an md device, once created by an open, remains active
at least until some md 'ioctl' has been made on it. This means that
all normal usage of md devices will allow them to disappear promptly
when not needed, but the worst that an incorrect usage will do it
cause an inactive md device to be left in existence (it can easily be
removed).
As an array can be stopped by writing to a sysfs attribute
echo clear > /sys/block/mdXXX/md/array_state
we need to use scheduled work for deleting the gendisk and other
kobjects. This allows us to wait for any pending gendisk deletion to
complete by simply calling flush_scheduled_work().
Signed-off-by: NeilBrown <neilb@suse.de>
