linux-stable.git/drivers/md/raid1.c, branch linux-3.4.y

Fix incomplete backport of commit 423f04d63cf4

2016-10-26T15:15:44+00:00

Signed-off-by: Zefan Li

raid1: include bio_end_io_list in nr_queued to prevent freeze_array hang

2016-04-27T10:55:30+00:00

commit ccfc7bf1f09d6190ef86693ddc761d5fe3fa47cb upstream.

If raid1d is handling a mix of read and write errors, handle_read_error's
call to freeze_array can get stuck.

This can happen because, though the bio_end_io_list is initially drained,
writes can be added to it via handle_write_finished as the retry_list
is processed. These writes contribute to nr_pending but are not included
in nr_queued.

If a later entry on the retry_list triggers a call to handle_read_error,
freeze array hangs waiting for nr_pending == nr_queued+extra. The writes
on the bio_end_io_list aren't included in nr_queued so the condition will
never be satisfied.

To prevent the hang, include bio_end_io_list writes in nr_queued.

There's probably a better way to handle decrementing nr_queued, but this
seemed like the safest way to avoid breaking surrounding code.

I'm happy to supply the script I used to repro this hang.

Fixes: 55ce74d4bfe1b(md/raid1: ensure device failure recorded before write request returns.)
Signed-off-by: Nate Dailey 
Signed-off-by: Shaohua Li 
Signed-off-by: Zefan Li

md/raid1: don't clear bitmap bit when bad-block-list write fails.

2016-04-27T10:55:22+00:00

commit bd8688a199b864944bf62eebed0ca13b46249453 upstream.

When a write fails and a bad-block-list is present, we can
update the bad-block-list instead of writing the data.  If
this succeeds then it is OK clear the relevant bitmap-bit as
no further 'sync' of the block is needed.

However if writing the bad-block-list fails then we need to
treat the write as failed and particularly must not clear
the bitmap bit.  Otherwise the device can be re-added (after
any hardware connection issues are resolved) and because the
relevant bit in the bitmap is clear, that block will not be
resynced.  This leads to data corruption.

We already delay the final bio_endio() on the write until
the bad-block-list is written so that when the write
returns: either that data is safe, the bad-block record is
safe, or the fact that the device is faulty is safe.
However we *don't* delay the clearing of the bitmap, so the
bitmap bit can be recorded as cleared before we know if the
bad-block-list was written safely.

So: delay that until the write really is safe.
i.e. move the call to close_write() until just before
calling bio_endio(), and recheck the 'is array degraded'
status before making that call.

This bug goes back to v3.1 when bad-block-lists were
introduced, though it only affects arrays created with
mdadm-3.3 or later as only those have bad-block lists.

Backports will require at least
Commit: 55ce74d4bfe1 ("md/raid1: ensure device failure recorded before write request returns.")
as well.  I'll send that to 'stable' separately.

Note that of the two tests of R1BIO_WriteError that this
patch adds, the first is certain to fail and the second is
certain to succeed.  However doing it this way makes the
patch more obviously correct.  I will tidy the code up in a
future merge window.

Reported-and-tested-by: Nate Dailey 
Cc: Jes Sorensen 
Fixes: cd5ff9a16f08 ("md/raid1:  Handle write errors by updating badblock log.")
Signed-off-by: NeilBrown 
Signed-off-by: Zefan Li

md/raid1: ensure device failure recorded before write request returns.

2016-04-27T10:55:21+00:00

commit 55ce74d4bfe1b9444436264c637f39a152d1e5ac upstream.

When a write to one of the legs of a RAID1 fails, the failure is
recorded in the metadata of the other leg(s) so that after a restart
the data on the failed drive wont be trusted even if that drive seems
to be working again  (maybe a cable was unplugged).

Similarly when we record a bad-block in response to a write failure,
we must not let the write complete until the bad-block update is safe.

Currently there is no interlock between the write request completing
and the metadata update.  So it is possible that the write will
complete, the app will confirm success in some way, and then the
machine will crash before the metadata update completes.

This is an extremely small hole for a racy to fit in, but it is
theoretically possible and so should be closed.

So:
 - set MD_CHANGE_PENDING when requesting a metadata update for a
   failed device, so we can know with certainty when it completes
 - queue requests that experienced an error on a new queue which
   is only processed after the metadata update completes
 - call raid_end_bio_io() on bios in that queue when the time comes.

Signed-off-by: NeilBrown 
Signed-off-by: Zefan Li

md/raid1: extend spinlock to protect raid1_end_read_request against inconsistencies

2016-03-21T01:17:50+00:00

commit 423f04d63cf421ea436bcc5be02543d549ce4b28 upstream.

raid1_end_read_request() assumes that the In_sync bits are consistent
with the ->degaded count.
raid1_spare_active updates the In_sync bit before the ->degraded count
and so exposes an inconsistency, as does error()
So extend the spinlock in raid1_spare_active() and error() to hide those
inconsistencies.

This should probably be part of
  Commit: 34cab6f42003 ("md/raid1: fix test for 'was read error from
  last working device'.")
as it addresses the same issue.  It fixes the same bug and should go
to -stable for same reasons.

Fixes: 76073054c95b ("md/raid1: clean up read_balance.")
Signed-off-by: NeilBrown 
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li

md/raid1: fix test for 'was read error from last working device'.

2016-03-21T01:17:47+00:00

commit 34cab6f42003cb06f48f86a86652984dec338ae9 upstream.

When we get a read error from the last working device, we don't
try to repair it, and don't fail the device.  We simple report a
read error to the caller.

However the current test for 'is this the last working device' is
wrong.
When there is only one fully working device, it assumes that a
non-faulty device is that device.  However a spare which is rebuilding
would be non-faulty but so not the only working device.

So change the test from "!Faulty" to "In_sync".  If ->degraded says
there is only one fully working device and this device is in_sync,
this must be the one.

This bug has existed since we allowed read_balance to read from
a recovering spare in v3.0

Reported-and-tested-by: Alexander Lyakas 
Fixes: 76073054c95b ("md/raid1: clean up read_balance.")
Signed-off-by: NeilBrown 
Signed-off-by: Zefan Li

md: Fix skipping recovery for read-only arrays.

2013-11-13T03:01:48+00:00

commit 61e4947c99c4494336254ec540c50186d186150b upstream.

Since:
        commit 7ceb17e87bde79d285a8b988cfed9eaeebe60b86
        md: Allow devices to be re-added to a read-only array.

spares are activated on a read-only array. In case of raid1 and raid10
personalities it causes that not-in-sync devices are marked in-sync
without checking if recovery has been finished.

If a read-only array is degraded and one of its devices is not in-sync
(because the array has been only partially recovered) recovery will be skipped.

This patch adds checking if recovery has been finished before marking a device
in-sync for raid1 and raid10 personalities. In case of raid5 personality
such condition is already present (at raid5.c:6029).

Bug was introduced in 3.10 and causes data corruption.

Signed-off-by: Pawel Baldysiak 
Signed-off-by: Lukasz Dorau 
Signed-off-by: NeilBrown 
Signed-off-by: Greg Kroah-Hartman

md/raid1,raid10: use freeze_array in place of raise_barrier in various places.

2013-08-20T15:26:28+00:00

commit e2d59925221cd562e07fee38ec8839f7209ae603 upstream.

Various places in raid1 and raid10 are calling raise_barrier when they
really should call freeze_array.
The former is only intended to be called from "make_request".
The later has extra checks for 'nr_queued' and makes a call to
flush_pending_writes(), so it is safe to call it from within the
management thread.

Using raise_barrier will sometimes deadlock.  Using freeze_array
should not.

As 'freeze_array' currently expects one request to be pending (in
handle_read_error - the only previous caller), we need to pass
it the number of pending requests (extra) to ignore.

The deadlock was made particularly noticeable by commits
050b66152f87c7 (raid10) and 6b740b8d79252f13 (raid1) which
appeared in 3.4, so the fix is appropriate for any -stable
kernel since then.

This patch probably won't apply directly to some early kernels and
will need to be applied by hand.

Cc: stable@vger.kernel.org
Reported-by: Alexander Lyakas 
Signed-off-by: NeilBrown 
[adjust context to make it can be apply on top of 3.4 ]
Signed-off-by: Jack Wang 
Signed-off-by: Greg Kroah-Hartman

md/raid1: consider WRITE as successful only if at least one non-Faulty and non-rebuilding drive completed it.

2013-06-20T18:58:46+00:00

commit 3056e3aec8d8ba61a0710fb78b2d562600aa2ea7 upstream.

Without that fix, the following scenario could happen:

- RAID1 with drives A and B; drive B was freshly-added and is rebuilding
- Drive A fails
- WRITE request arrives to the array. It is failed by drive A, so
r1_bio is marked as R1BIO_WriteError, but the rebuilding drive B
succeeds in writing it, so the same r1_bio is marked as
R1BIO_Uptodate.
- r1_bio arrives to handle_write_finished, badblocks are disabled,
md_error()->error() does nothing because we don't fail the last drive
of raid1
- raid_end_bio_io()  calls call_bio_endio()
- As a result, in call_bio_endio():
        if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
                clear_bit(BIO_UPTODATE, &bio->bi_flags);
this code doesn't clear the BIO_UPTODATE flag, and the whole master
WRITE succeeds, back to the upper layer.

So we returned success to the upper layer, even though we had written
the data onto the rebuilding drive only. But when we want to read the
data back, we would not read from the rebuilding drive, so this data
is lost.

[neilb - applied identical change to raid10 as well]

This bug can result in lost data, so it is suitable for any
-stable kernel.

Signed-off-by: Alex Lyakas 
Signed-off-by: NeilBrown 
Signed-off-by: Greg Kroah-Hartman

md/raid1: Fix assembling of arrays containing Replacements.

2012-11-05T08:50:41+00:00

commit 02b898f2f04e418094f0093a3ad0b415bcdbe8eb upstream.

setup_conf in raid1.c uses conf->raid_disks before assigning
a value.  It is used when including 'Replacement' devices.

The consequence is that assembling an array which contains a
replacement will misbehave and either not include the replacement, or
not include the device being replaced.

Though this doesn't lead directly to data corruption, it could lead to
reduced data safety.

So use mddev->raid_disks, which is initialised, instead.

Bug was introduced by commit c19d57980b38a5bb613a898937a1cf85f422fb9b
      md/raid1: recognise replacements when assembling arrays.

in 3.3, so fix is suitable for 3.3.y thru 3.6.y.

Signed-off-by: NeilBrown 
Signed-off-by: Greg Kroah-Hartman