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  1. 23 12月, 2011 6 次提交
    • N
      md/raid5: preferentially read from replacement device if possible. · 14a75d3e
      由 NeilBrown 提交于 
      If a replacement device is present and has been recovered far enough,
then use it for reading into the stripe cache.

If we get an error we don't try to repair it, we just fail the device.
A replacement device that gives errors does not sound sensible.

This requires removing the setting of R5_ReadError when we get
a read error during a read that bypasses the cache.  It was probably
a bad idea anyway as we don't know that every block in the read
caused an error, and it could cause ReadError to be set for the
replacement device, which is bad.
Signed-off-by: NNeilBrown <neilb@suse.de>
      14a75d3e
    • N
      md/raid5: remove redundant bio initialisations. · 995c4275
      由 NeilBrown 提交于 
      We current initialise some fields of a bio when preparing a
stripe_head, and again just before submitting the request.

Remove the duplication by only setting the fields that lower level
devices don't touch in raid5_build_block, and only set the changeable
fields in ops_run_io.
Reviewed-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NNeilBrown <neilb@suse.de>
      995c4275
    • N
      md/raid5: allow each slot to have an extra replacement device · 671488cc
      由 NeilBrown 提交于 
      Just enhance data structures to record a second device per slot to be
used as a 'replacement' device, replacing the original.
We also have a second bio in each slot in each stripe_head.  This will
only be used when writing to the array - we need to write to both the
original and the replacement at the same time, so will need two bios.

For now, only try using the replacement drive for aligned-reads.
In this case, we prefer the replacement if it has been recovered far
enough, otherwise use the original.

This includes a small enhancement.  Previously we would only do
aligned reads if the target device was fully recovered.  Now we also
do them if it has recovered far enough.
Reviewed-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NNeilBrown <neilb@suse.de>
      671488cc
    • N
      md: change hot_remove_disk to take an rdev rather than a number. · b8321b68
      由 NeilBrown 提交于 
      Soon an array will be able to have multiple devices with the
same raid_disk number (an original and a replacement).  So removing
a device based on the number won't work.  So pass the actual device
handle instead.
Reviewed-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NNeilBrown <neilb@suse.de>
      b8321b68
    • N
      md/raid5: be more thorough in calculating 'degraded' value. · 908f4fbd
      由 NeilBrown 提交于 
      When an array is being reshaped to change the number of devices,
the two halves can be differently degraded.  e.g. one could be
missing a device and the other not.

So we need to be more careful about calculating the 'degraded'
attribute.

Instead of just inc/dec at appropriate times, perform a full
re-calculation examining both possible cases.  This doesn't happen
often so it not a big cost, and we already have most of the code to
do it.
Signed-off-by: NNeilBrown <neilb@suse.de>
      908f4fbd
    • N
      md/raid5: ensure correct assessment of drives during degraded reshape. · 30d7a483
      由 NeilBrown 提交于 
      While reshaping a degraded array (as when reshaping a RAID0 by first
converting it to a degraded RAID4) we currently get confused about
which devices are in_sync.  In most cases we get it right, but in the
region that is being reshaped we need to treat non-failed devices as
in-sync when we have the data but haven't actually written it out yet.
Reported-by: NAdam Kwolek <adam.kwolek@intel.com>
Signed-off-by: NNeilBrown <neilb@suse.de>
      30d7a483
  3. 09 12月, 2011 1 次提交
  5. 08 12月, 2011 1 次提交
    • N
      md/raid5: never wait for bad-block acks on failed device. · 9283d8c5
      由 NeilBrown 提交于 
      Once a device is failed we really want to completely ignore it.
It should go away soon anyway.

In particular the presence of bad blocks on it should not cause us to
block as we won't be trying to write there anyway.

So as soon as we can check if a device is Faulty, do so and pretend
that it is already gone if it is Faulty.
Signed-off-by: NNeilBrown <neilb@suse.de>
      9283d8c5
  7. 08 11月, 2011 2 次提交
  9. 01 11月, 2011 1 次提交
  11. 26 10月, 2011 2 次提交
    • N
      md: Fix some bugs in recovery_disabled handling. · d890fa2b
      由 NeilBrown 提交于 
      In 3.0 we changed the way recovery_disabled was handle so that instead
of testing against zero, we test an mddev-> value against a conf->
value.
Two problems:
  1/ one place in raid1 was missed and still sets to '1'.
  2/ We didn't explicitly set the conf-> value at array creation
     time.
     It defaulted to '0' just like the mddev value does so they
     could appear equal and thus disable recovery.
     This did not affect normal 'md' as it calls bind_rdev_to_array
     which changes the mddev value.  However the dmraid interface
     doesn't call this and so doesn't change ->recovery_disabled; so at
     array start all recovery is incorrectly disabled.

So initialise the 'conf' value to one less that the mddev value, so
the will only be the same when explicitly set that way.
Reported-by: NJonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NNeilBrown  <neilb@suse.de>
      d890fa2b
    • N
      md/raid5: fix bug that could result in reads from a failed device. · 355840e7
      由 NeilBrown 提交于 
      This bug was introduced in 415e72d0
which was in 2.6.36.

There is a small window of time between when a device fails and when
it is removed from the array.  During this time we might still read
from it, but we won't write to it - so it is possible that we could
read stale data.

We didn't need the test of 'Faulty' before because the test on
In_sync is sufficient.  Since we started allowing reads from the early
part of non-In_sync devices we need a test on Faulty too.

This is suitable for any kernel from 2.6.36 onwards, though the patch
might need a bit of tweaking in 3.0 and earlier.

Cc: stable@kernel.org
Signed-off-by: NNeilBrown <neilb@suse.de>
      355840e7
  13. 11 10月, 2011 5 次提交
  15. 07 10月, 2011 3 次提交
  17. 21 9月, 2011 1 次提交
    • N
      md: Avoid waking up a thread after it has been freed. · 01f96c0a
      由 NeilBrown 提交于 
      Two related problems:

1/ some error paths call "md_unregister_thread(mddev->thread)"
   without subsequently clearing ->thread.  A subsequent call
   to mddev_unlock will try to wake the thread, and crash.

2/ Most calls to md_wakeup_thread are protected against the thread
   disappeared either by:
      - holding the ->mutex
      - having an active request, so something else must be keeping
        the array active.
   However mddev_unlock calls md_wakeup_thread after dropping the
   mutex and without any certainty of an active request, so the
   ->thread could theoretically disappear.
   So we need a spinlock to provide some protections.

So change md_unregister_thread to take a pointer to the thread
pointer, and ensure that it always does the required locking, and
clears the pointer properly.
Reported-by: N"Moshe Melnikov" <moshe@zadarastorage.com>
Signed-off-by: NNeilBrown <neilb@suse.de>
cc: stable@kernel.org
      01f96c0a
  19. 12 9月, 2011 1 次提交
  21. 31 8月, 2011 1 次提交
    • N
      md/raid5: fix a hang on device failure. · 43220aa0
      由 NeilBrown 提交于 
      Waiting for a 'blocked' rdev to become unblocked in the raid5d thread
cannot work with internal metadata as it is the raid5d thread which
will clear the blocked flag.
This wasn't a problem in 3.0 and earlier as we only set the blocked
flag when external metadata was used then.
However we now set it always, so we need to be more careful.
Signed-off-by: NNeilBrown <neilb@suse.de>
      43220aa0
  23. 28 7月, 2011 7 次提交
    • N
      md/raid5: Clear bad blocks on successful write. · b84db560
      由 NeilBrown 提交于 
      On a successful write to a known bad block, flag the sh
so that raid5d can remove the known bad block from the list.
Signed-off-by: NNeilBrown <neilb@suse.de>
      b84db560
    • N
      md/raid5. Don't write to known bad block on doubtful devices. · 73e92e51
      由 NeilBrown 提交于 
      If a device has seen write errors, don't write to any known
bad blocks on that device.
Signed-off-by: NNeilBrown <neilb@suse.de>
      73e92e51
    • N
      md/raid5: write errors should be recorded as bad blocks if possible. · bc2607f3
      由 NeilBrown 提交于 
      When a write error is detected, don't mark the device as failed
immediately but rather record the fact for handle_stripe to deal with.

Handle_stripe then attempts to record a bad block.  Only if that fails
does the device get marked as faulty.
Signed-off-by: NNeilBrown <neilb@suse.de>
      bc2607f3
    • N
      md/raid5: use bad-block log to improve handling of uncorrectable read errors. · 7f0da59b
      由 NeilBrown 提交于 
      If we get an uncorrectable read error - record a bad block rather than
failing the device.
And if these errors (which may be due to known bad blocks) cause
recovery to be impossible, record a bad block on the recovering
devices, or abort the recovery.

As we might abort a recovery without failing a device we need to teach
RAID5 about recovery_disabled handling.
Signed-off-by: NNeilBrown <neilb@suse.de>
      7f0da59b
    • N
      md/raid5: avoid reading from known bad blocks. · 31c176ec
      由 NeilBrown 提交于 
      There are two times that we might read in raid5:
1/ when a read request fits within a chunk on a single
   working device.
   In this case, if there is any bad block in the range of
   the read, we simply fail the cache-bypass read and
   perform the read though the stripe cache.

2/ when reading into the stripe cache.  In this case we
   mark as failed any device which has a bad block in that
   strip (1 page wide).
   Note that we will both avoid reading and avoid writing.
   This is correct (as we will never read from the block, there
   is no point writing), but not optimal (as writing could 'fix'
   the error) - that will be addressed later.

If we have not seen any write errors on the device yet, we treat a bad
block like a recent read error.  This will encourage an attempt to fix
the read error which will either generate a write error, or will
ensure good data is stored there.  We don't yet forget the bad block
in that case.  That comes later.

Now that we honour bad blocks when reading we can allow devices with
bad blocks into the array.
Signed-off-by: NNeilBrown <neilb@suse.de>
      31c176ec
    • N
      md: make it easier to wait for bad blocks to be acknowledged. · de393cde
      由 NeilBrown 提交于 
      It is only safe to choose not to write to a bad block if that bad
block is safely recorded in metadata - i.e. if it has been
'acknowledged'.

If it hasn't we need to wait for the acknowledgement.

We support that using rdev->blocked wait and
md_wait_for_blocked_rdev by introducing a new device flag
'BlockedBadBlock'.

This flag is only advisory.
It is cleared whenever we acknowledge a bad block, so that a waiter
can re-check the particular bad blocks that it is interested it.

It should be set by a caller when they find they need to wait.
This (set after test) is inherently racy, but as
md_wait_for_blocked_rdev already has a timeout, losing the race will
have minimal impact.

When we clear "Blocked" was also clear "BlockedBadBlocks" incase it
was set incorrectly (see above race).

We also modify the way we manage 'Blocked' to fit better with the new
handling of 'BlockedBadBlocks' and to make it consistent between
externally managed and internally managed metadata.   This requires
that each raidXd loop checks if the metadata needs to be written and
triggers a write (md_check_recovery) if needed.  Otherwise a queued
write request might cause raidXd to wait for the metadata to write,
and only that thread can write it.

Before writing metadata, we set FaultRecorded for all devices that
are Faulty, then after writing the metadata we clear Blocked for any
device for which the Fault was certainly Recorded.

The 'faulty' device flag now appears in sysfs if the device is faulty
*or* it has unacknowledged bad blocks.  So user-space which does not
understand bad blocks can continue to function correctly.
User space which does, should not assume a device is faulty until it
sees the 'faulty' flag, and then sees the list of unacknowledged bad
blocks is empty.
Signed-off-by: NNeilBrown <neilb@suse.de>
      de393cde
    • N
      md: don't allow arrays to contain devices with bad blocks. · 34b343cf
      由 NeilBrown 提交于 
      As no personality understand bad block lists yet, we must
reject any device that is known to contain bad blocks.
As the personalities get taught, these tests can be removed.

This only applies to raid1/raid5/raid10.
For linear/raid0/multipath/faulty the whole concept of bad blocks
doesn't mean anything so there is no point adding the checks.
Signed-off-by: NNeilBrown <neilb@suse.de>
Reviewed-by: NNamhyung Kim <namhyung@gmail.com>
      34b343cf
  25. 27 7月, 2011 9 次提交