Commit Graph

2352 Commits

Author SHA1 Message Date
Linus Torvalds
912afc3616 Improve multipath's retrying mechanism in some defined circumstances
and provide a simple reserve/release mechanism for userspace tools to
 access thin provisioning metadata while the pool is in use.
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Merge tag 'dm-3.5-changes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

Pull device-mapper updates from Alasdair G Kergon:
 "Improve multipath's retrying mechanism in some defined circumstances
  and provide a simple reserve/release mechanism for userspace tools to
  access thin provisioning metadata while the pool is in use."

* tag 'dm-3.5-changes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm:
  dm thin: provide userspace access to pool metadata
  dm thin: use slab mempools
  dm mpath: allow ioctls to trigger pg init
  dm mpath: delay retry of bypassed pg
  dm mpath: reduce size of struct multipath
2012-06-02 17:39:40 -07:00
Joe Thornber
cc8394d86f dm thin: provide userspace access to pool metadata
This patch implements two new messages that can be sent to the thin
pool target allowing it to take a snapshot of the _metadata_.  This,
read-only snapshot can be accessed by userland, concurrently with the
live target.

Only one metadata snapshot can be held at a time.  The pool's status
line will give the block location for the current msnap.

Since version 0.1.5 of the userland thin provisioning tools, the
thin_dump program displays the msnap as follows:

    thin_dump -m <msnap root> <metadata dev>

Available here: https://github.com/jthornber/thin-provisioning-tools

Now that userland can access the metadata we can do various things
that have traditionally been kernel side tasks:

     i) Incremental backups.

     By using metadata snapshots we can work out what blocks have
     changed over time.  Combined with data snapshots we can ensure
     the data doesn't change while we back it up.

     A short proof of concept script can be found here:

     https://github.com/jthornber/thinp-test-suite/blob/master/incremental_backup_example.rb

     ii) Migration of thin devices from one pool to another.

     iii) Merging snapshots back into an external origin.

     iv) Asyncronous replication.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-06-03 00:30:01 +01:00
Mike Snitzer
a24c25696b dm thin: use slab mempools
Use dedicated caches prefixed with a "dm_" name rather than relying on
kmalloc mempools backed by generic slab caches so the memory usage of
thin provisioning (and any leaks) can be accounted for independently.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-06-03 00:30:00 +01:00
Mikulas Patocka
35991652ba dm mpath: allow ioctls to trigger pg init
After the failure of a group of paths, any alternative paths that
need initialising do not become available until further I/O is sent to
the device.  Until this has happened, ioctls return -EAGAIN.

With this patch, new paths are made available in response to an ioctl
too.  The processing of the ioctl gets delayed until this has happened.

Instead of returning an error, we submit a work item to kmultipathd
(that will potentially activate the new path) and retry in ten
milliseconds.

Note that the patch doesn't retry an ioctl if the ioctl itself fails due
to a path failure.  Such retries should be handled intelligently by the
code that generated the ioctl in the first place, noting that some SCSI
commands should not be retried because they are not idempotent (XOR write
commands).  For commands that could be retried, there is a danger that
if the device rejected the SCSI command, the path could be errorneously
marked as failed, and the request would be retried on another path which
might fail too.  It can be determined if the failure happens on the
device or on the SCSI controller, but there is no guarantee that all
SCSI drivers set these flags correctly.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-06-03 00:29:58 +01:00
Mike Christie
f220fd4efb dm mpath: delay retry of bypassed pg
If I/O needs retrying and only bypassed priority groups are available,
set the pg_init_delay_retry flag to wait before retrying.

If, for example, the reason for the bypass is that the controller is
getting reset or there is a firmware upgrade happening, retrying right
away would cause a flood of log messages and retries for what could be a
few seconds or even several minutes.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-06-03 00:29:45 +01:00
Mike Snitzer
1fbdd2b3a3 dm mpath: reduce size of struct multipath
Move multipath structure's 'lock' and 'queue_size' members to eliminate
two 4-byte holes.  Also use a bit within a single unsigned int for each
existing flag (saves 8-bytes).  This allows future flags to be added
without each consuming an unsigned int.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-06-03 00:29:43 +01:00
Linus Torvalds
c80ddb5263 md updates for 3.5
Main features:
  - RAID10 arrays can be reshapes - adding and removing devices and
    changing chunks (not 'far' array though)
  - allow RAID5 arrays to be reshaped with a backup file (not tested
    yet, but the priciple works fine for RAID10).
  - arrays can be reshaped while a bitmap is present - you no longer
    need to remove it first
  - SSSE3 support for RAID6 syndrome calculations
 
 and of course a number of minor fixes etc.
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Merge tag 'md-3.5' of git://neil.brown.name/md

Pull md updates from NeilBrown:
 "It's been a busy cycle for md - lots of fun stuff here..  if you like
  this kind of thing :-)

  Main features:
   - RAID10 arrays can be reshaped - adding and removing devices and
     changing chunks (not 'far' array though)
   - allow RAID5 arrays to be reshaped with a backup file (not tested
     yet, but the priciple works fine for RAID10).
   - arrays can be reshaped while a bitmap is present - you no longer
     need to remove it first
   - SSSE3 support for RAID6 syndrome calculations

  and of course a number of minor fixes etc."

* tag 'md-3.5' of git://neil.brown.name/md: (56 commits)
  md/bitmap: record the space available for the bitmap in the superblock.
  md/raid10: Remove extras after reshape to smaller number of devices.
  md/raid5: improve removal of extra devices after reshape.
  md: check the return of mddev_find()
  MD RAID1: Further conditionalize 'fullsync'
  DM RAID: Use md_error() in place of simply setting Faulty bit
  DM RAID: Record and handle missing devices
  DM RAID: Set recovery flags on resume
  md/raid5: Allow reshape while a bitmap is present.
  md/raid10: resize bitmap when required during reshape.
  md: allow array to be resized while bitmap is present.
  md/bitmap: make sure reshape request are reflected in superblock.
  md/bitmap: add bitmap_resize function to allow bitmap resizing.
  md/bitmap: use DIV_ROUND_UP instead of open-code
  md/bitmap: create a 'struct bitmap_counts' substructure of 'struct bitmap'
  md/bitmap: make bitmap bitops atomic.
  md/bitmap: make _page_attr bitops atomic.
  md/bitmap: merge bitmap_file_unmap and bitmap_file_put.
  md/bitmap: remove async freeing of bitmap file.
  md/bitmap: convert some spin_lock_irqsave to spin_lock_irq
  ...
2012-05-23 17:08:40 -07:00
NeilBrown
1dff2b87a3 md/bitmap: record the space available for the bitmap in the superblock.
Now that bitmaps can grow and shrink it is best if we record
how much space is available.  This means that when
we reduce the size of the bitmap we won't "lose" the space
for late when we might want to increase the size of the bitmap
again.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:34 +10:00
NeilBrown
63aced6102 md/raid10: Remove extras after reshape to smaller number of devices.
When a reshape which reduced the number of devices finishes
we must remove the extra devices.

So ensure  that raid10_remove_disk won't try to keep them, and
have raid10_finish_reshape clear the 'in_sync' flag.  Then
remove_and_add_spares will be able to remove them.

Reported-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:33 +10:00
NeilBrown
da7613b8b0 md/raid5: improve removal of extra devices after reshape.
After a reshape which reduced the number of devices we need
to disconnect the extra devices.
The code for this doesn't currently handle 'replacement' devices.
It is very unlikely that such devices will be present, but it is
safest to handle them anyway.

So simplify the handling.  Just clear In_sync and leave it
to remove_and_add_spaces (which will be called soon) to do
the real works.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:33 +10:00
Yuanhan Liu
0c098220e2 md: check the return of mddev_find()
Check the return of mddev_find(), since it may fail due to out of
memeory or out of usable minor number.

The reason I chose -ENODEV instead of -ENOMEM or something else is
md_alloc() function chose that ;)

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:32 +10:00
Jonathan Brassow
4f0a5e012c MD RAID1: Further conditionalize 'fullsync'
A RAID1 device does not necessarily need a fullsync if the bitmap can be used instead.

Similar to commit d6b212f4b1 in raid5.c, if a raid1
device can be brought back (i.e. from a transient failure) it shouldn't need a
complete resync.  Provided the bitmap is not to old, it will have recorded the areas
of the disk that need recovery.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:31 +10:00
Jonathan Brassow
c32fb9e7ec DM RAID: Use md_error() in place of simply setting Faulty bit
When encountering an error while reading the superblock, call md_error.

We are currently setting the 'Faulty' bit on one of the array devices when an
error is encountered while reading the superblock of a dm-raid array.  We should
be calling md_error(), as it handles the error more completely.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:31 +10:00
Jonathan Brassow
81f382f9e0 DM RAID: Record and handle missing devices
Missing dm-raid devices should be recorded in the superblock

When specifying the devices that compose a DM RAID array, it is possible to denote
failed or missing devices with '-'s.  When this occurs, we must record this in the
superblock.  We do this by checking if the array position's data device is missing
and then forcing MD to record the superblock by setting 'MD_CHANGE_DEVS' in
'raid_resume'.  If we do not cause the superblock to be rewritten by the resume
function, it is possible for a stale superblock to be written by an out-going
in-active table (during 'raid_dtr').

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:30 +10:00
Jonathan Brassow
47525e59e4 DM RAID: Set recovery flags on resume
Properly initialize MD recovery flags when resuming device-mapper devices.

When a device-mapper device is suspended, all I/O must stop.  This is done by
calling 'md_stop_writes' and 'mddev_suspend'.  These calls in-turn manipulate
the recovery flags - including setting 'MD_RECOVERY_FROZEN'.  The DM device
may have been suspended while recovery was not yet complete, so the process
needs to pick-up where it left off.  Since 'mddev_resume' does not unset
'MD_RECOVERY_FROZEN' and set 'MD_RECOVERY_NEEDED', we must do it ourselves.
'MD_RECOVERY_NEEDED' can safely be set in 'mddev_resume', but 'MD_RECOVERY_FROZEN'
must be set outside of 'mddev_resume' due to how MD handles RAID reshaping.
(e.g.  It is possible for a user to delay reshaping a RAID5->RAID6 by purposefully
setting 'MD_RECOVERY_FROZEN'.  Clearing it in 'mddev_resume' would override the
desired behavior.)

Because 'mddev_resume' already unconditionally calls 'md_wakeup_thread(mddev->thread)'
there is no need to make this call from 'raid_resume' since it calls 'mddev_resume'.

Also clean up where  level_store calls mddev_resume() - it current
duplicates some of the funcitons of that call. - NB

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:29 +10:00
NeilBrown
30b67645fa md/raid5: Allow reshape while a bitmap is present.
We always should have allowed this.  A raid5 reshape doesn't change
the size of the bitmap, so not need to restrict it.

Also add a test to make sure we don't try to start a reshape on a
failed array.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:28 +10:00
NeilBrown
bb63a7019d md/raid10: resize bitmap when required during reshape.
If a reshape changes the size of the array, then we can now
update the bitmap to suit - so do so.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:28 +10:00
NeilBrown
a4a6125a07 md: allow array to be resized while bitmap is present.
Now that bitmaps can be resized, we can allow an array to be resized
while the bitmap is present.

This only covers resizing that involves changing the effective size
of member devices, not resizing that changes the number of devices.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:27 +10:00
NeilBrown
b81a040481 md/bitmap: make sure reshape request are reflected in superblock.
As a reshape may change the sync_size and/or chunk_size, we need
to update these whenever we write out the bitmap superblock.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:26 +10:00
NeilBrown
d60b479d17 md/bitmap: add bitmap_resize function to allow bitmap resizing.
This function will allocate the new data structures and copy
bits across from old to new, allowing for the possibility that the
chunksize has changed.

Use the same function for performing the initial allocation
of the structures.  This improves test coverage.

When bitmap_resize is used to resize an existing bitmap, it
only copies '1' bits in, not '0' bits.
So when allocating the bitmap, ensure everything is initialised
to ZERO.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:25 +10:00
NeilBrown
15702d7fb6 md/bitmap: use DIV_ROUND_UP instead of open-code
Also take the opportunity to simplify CHUNK_BLOCK_RATIO.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:25 +10:00
NeilBrown
40cffcc0e8 md/bitmap: create a 'struct bitmap_counts' substructure of 'struct bitmap'
The new "struct bitmap_counts" contains all the fields that are
related to counting the number of active writes in each bitmap chunk.

Having this separate will make it easier to change the chunksize
or overall size of a bitmap atomically.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:24 +10:00
NeilBrown
63c68268b2 md/bitmap: make bitmap bitops atomic.
This allows us to remove spinlock protection which is
more heavy-weight than simple atomics.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:23 +10:00
NeilBrown
bdfd114073 md/bitmap: make _page_attr bitops atomic.
Using e.g. set_bit instead of __set_bit and using test_and_clear_bit
allow us to remove some locking and contract other locked ranges.

It is rare that we set or clear a lot of these bits, so gain should
outweigh any cost.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:22 +10:00
NeilBrown
fae7d326cd md/bitmap: merge bitmap_file_unmap and bitmap_file_put.
There functions really do one thing together: release the
'bitmap_storage'.  So make them just one function.

Since we removed the locking (previous patch), we don't need to zero
any fields before freeing them, so it all becomes a bit simpler.


Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:21 +10:00
NeilBrown
62f82faace md/bitmap: remove async freeing of bitmap file.
There is no real value in freeing things the moment there is an error.
It is just as good to free the bitmap file and pages when the bitmap
is explicitly removed (and replaced?) or at shutdown.

With this gone, the bitmap will only disappear when the array is
quiescent, so we can remove some locking.

As the 'filemap' doesn't disappear now, include extra checks before
trying to write any of it out.
Also remove the check for "has it disappeared" in
bitmap_daemon_write().


Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:21 +10:00
NeilBrown
7466712347 md/bitmap: convert some spin_lock_irqsave to spin_lock_irq
All of these sites can only be called from process context with
irqs enabled, so using irqsave/irqrestore just adds noise.
Remove it.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:19 +10:00
NeilBrown
b405fe91e5 md/bitmap: use set_bit, test_bit, etc for operation on bitmap->flags.
We currently use '&' and '|' which isn't the norm in the kernel
and doesn't allow easy atomicity.
So change to bit numbers and {set,clear,test}_bit.
This allows us to remove a spinlock/unlock (which was dubious anyway)
and some other simplifications.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:15 +10:00
NeilBrown
84e923453e md/bitmap: remove single-bit manipulation on sb->state
Just do single-bit manipulations on bitmap->flags and copy whole
value between that and sb->state.

This will allow next patch which changes how bit manipulations are
performed on bitmap->flags.

This does result in BITMAP_STALE not being set in sb by
bitmap_read_sb, however as the setting is determined by other
information in the 'sb' we do not lose information this way.
Normally, bitmap_load will be called shortly which will clear
BITMAP_STALE anyway.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:14 +10:00
NeilBrown
edbb79df67 md/bitmap: remove bitmap_mask_state
This function isn't really needed.  It sets or clears a flag in both
bitmap->flags and sb->state.
However both times it is called, bitmap_update_sb is called soon
afterwards which copies bitmap->flags to sb->state.
So just make changes to bitmap->flags, and open-code those rather than
hiding in a function.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:13 +10:00
NeilBrown
bc9891a885 md/bitmap: move storage allocation from bitmap_load to bitmap_create.
We should allocate memory for the storage-bitmap at create-time, not
load time.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:12 +10:00
NeilBrown
d1244cb062 md/bitmap: separate bitmap file allocation to its own function.
This will allow allocation before swapping in a new bitmap.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:12 +10:00
NeilBrown
9b1215c102 md/bitmap: store bytes in file rather than just in last page.
This number is more generally useful, and bytes-in-last-page is
easily extracted from it.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:11 +10:00
NeilBrown
1ec885cdd0 md/bitmap: move some fields of 'struct bitmap' into a 'storage' substruct.
This new 'struct bitmap_storage' reflects the external storage of the
bitmap.
Having this clearly defined will make it easier to change the storage
used while the array is active.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:10 +10:00
NeilBrown
d189122d4b md/bitmap: change *_page_attr() to take a page number, not a page.
Most often we have the page number, not the page.  And that is what
the  *_page_attr() functions really want.  So change the arguments to
take that number.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:09 +10:00
NeilBrown
27581e5ae0 md/bitmap: centralise allocation of bitmap file pages.
Instead of allocating pages in read_sb_page, read_page and
bitmap_read_sb, allocate them all in bitmap_init_from disk.

Also replace the hack of calling "attach_page_buffers(page, NULL)" to
ensure that free_buffer() won't complain, by putting a test for
PagePrivate in free_buffer().

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:08 +10:00
NeilBrown
ef99bf480d md/bitmap: allow a bitmap with no backing storage.
An md bitmap comprises two parts
 - internal counting of active writes per 'chunk'.
 - external storage of whether there are any active writes on
   each chunk

The second requires the first, but the first doesn't require the
second.

Not having backing storage means that the bitmap cannot expedite
resync after a crash, but it still allows us to expedite the recovery
of a recently-removed device.

So: allow a bitmap to exist even if there is no backing device.
In that case we default to 128M chunks.

A particular value of this is that we can remove and re-add a bitmap
(possibly of a different granularity) on a degraded array, and not
lose the information needed to fast-recover the missing device.

We don't actually activate these bitmaps yet - that will come
in a later patch.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:08 +10:00
NeilBrown
6409bb05a9 md/bitmap: add new 'space' attribute for bitmaps.
If we are to allow bitmaps to be resized when the array is resized,
we need to know how much space there is.

So create an attribute to store this information and set appropriate
defaults.

It can be set more precisely via sysfs, or future metadata extensions
may allow it to be recorded.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:07 +10:00
NeilBrown
bf07bb7d5b md/bitmap: disentangle two different 'pending' flags.
There are two different 'pending' concepts in the handling of the
write intent bitmap.

Firstly, a 'page' from the bitmap (which container PAGE_SIZE*8 bits)
may have changes (bits cleared) that should be written in due course.
There is no hurry for these and the page will transition from
PENDING to NEEDWRITE and will then be written, though if it ever
becomes DIRTY it will be written much sooner and PENDING will be
cleared.

Secondly, a page of counters - which contains PAGE_SIZE/2 counters, one
for each bit, can usefully have a 'pending' flag which indicates if
any of the counters are low (2 or 1) and ready to be processed by
bitmap_daemon_work().  If this flag is clear we can skip the whole
page.

These two concepts are currently combined in the bitmap-file flag.
This causes a tighter connection between the counters and the bitmap
file than I would like - as I want to add some flexibility to the
bitmap file.

So introduce a new flag with the page-of-counters, and rewrite
bitmap_daemon_work() so that it handles the two different 'pending'
concepts separately.

This also allows us to clear BITMAP_PAGE_PENDING when we write out
a dirty page, which may occasionally reduce the number of times we
write a page.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:06 +10:00
Shaohua Li
bc0934f047 raid5: support sync request
REQ_SYNC is ignored in current raid5 code. Block layer does use it to do
policy,
for example ioscheduler. This patch adds it.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:05 +10:00
Shaohua Li
cceeca43b5 raid5: remove unused variables
The two variables are useless.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:04 +10:00
majianpeng
5fdd2cf826 md/raid10: Fix memleak in r10buf_pool_alloc
If the allocation of rep1_bio fails, we currently don't free the 'bio'
of the same dev.

Reported by kmemleak.

Signed-off-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:03 +10:00
majianpeng
da8840a747 md/raid1: allow fix_read_error to read from recovering device.
When attempting to fix a read error, it is acceptable to read from a
device that is recovering, provided the recovery has got past the
place we are reading from.  This makes the test for "can we read from
here" the same as the test in read_balance.

Signed-off-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:03 +10:00
NeilBrown
4fa2f32768 md: move freeing of badblocks.page into md_rdev_clear
This ensures that it is always freed - there were case where
we failed to free the page.

Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:55:01 +10:00
NeilBrown
545c87957f md: dm-raid should call helper function to clear rdev.
dm-raid currently open-codes the freeing of some members of
and rdev.  It is more maintainable to have it call common code
from md.c which does this for all call-sites.

So remove free_disk_sb to md_rdev_clear, export it, and use it in
dm-raid.c

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:54:30 +10:00
NeilBrown
3ea7daa5d7 md/raid10: add reshape support
A 'near' or 'offset' lay RAID10 array can be reshaped to a different
'near' or 'offset' layout, a different chunk size, and a different
number of devices.
However the number of copies cannot change.

Unlike RAID5/6, we do not support having user-space backup data that
is being relocated during a 'critical section'.  Rather, the
data_offset of each device must change so that when writing any block
to a new location, it will not over-write any data that is still
'live'.

This means that RAID10 reshape is not supportable on v0.90 metadata.

The different between the old data_offset and the new_offset must be
at least the larger of the chunksize multiplied by offset copies of
each of the old and new layout. (for 'near' mode, offset_copies == 1).

A larger difference of around 64M seems useful for in-place reshapes
as more data can be moved between metadata updates.
Very large differences (e.g. 512M) seem to slow the process down due
to lots of long seeks (on oldish consumer graded devices at least).

Metadata needs to be updated whenever the place we are about to write
to is considered - by the current metadata - to still contain data in
the old layout.

[unbalanced locking fix from Dan Carpenter <dan.carpenter@oracle.com>]

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22 13:53:47 +10:00
NeilBrown
deb200d085 md/raid10: split out interpretation of layout to separate function.
We will soon be interpreting the layout (and chunksize etc) from
multiple places to support reshape.  So split it out into separate
function.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-21 09:28:33 +10:00
NeilBrown
f8c9e74ff0 md/raid10: Introduce 'prev' geometry to support reshape.
When RAID10 supports reshape it will need a 'previous' and a 'current'
geometry, so introduce that here.
Use the 'prev' geometry when before the reshape_position, and the
current 'geo' when beyond it.  At other times, use both as
appropriate.

For now, both are identical (And reshape_position is never set).

When we use the 'prev' geometry, we must use the old data_offset.
When we use the current (And a reshape is happening) we must use
the new_data_offset.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-21 09:28:33 +10:00
NeilBrown
c804cdecea md: use resync_max_sectors for reshape as well as resync.
Some resync type operations need to act on the address space of the
device, others on the address space of the array.

This only affects RAID10, so it sets resync_max_sectors to the array
size (it defaults to the device size), and that is currently used for
resync only.  However reshape of a RAID10 must be done against the
array size, not device size, so change code to use resync_max_sectors
for both the resync and the reshape cases.
This does not affect RAID5 or RAID1, just RAID10.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-21 09:28:33 +10:00
NeilBrown
1fdd6fc92f md: teach sync_page_io about new_data_offset.
Some code in raid1 and raid10 use sync_page_io to
read/write pages when responding to read errors.
As we will shortly support changing data_offset for
raid10, this function must understand new_data_offset.

So add that understanding.

Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-21 09:28:32 +10:00