linux-toradex.git/drivers/md/dm-raid1.c, branch v2.6.34.8

dm raid1: fix deadlock when suspending failed device

2010-03-06T02:32:35+00:00

To prevent deadlock, bios in the hold list should be flushed before
dm_rh_stop_recovery() is called in mirror_suspend().

The recovery can't start because there are pending bios and therefore
dm_rh_stop_recovery deadlocks.

When there are pending bios in the hold list, the recovery waits for
the completion of the bios after recovery_count is acquired.
The recovery_count is released when the recovery finished, however,
the bios in the hold list are processed after dm_rh_stop_recovery() in
mirror_presuspend(). dm_rh_stop_recovery() also acquires recovery_count,
then deadlock occurs.

Signed-off-by: Takahiro Yasui 
Signed-off-by: Alasdair G Kergon 
Reviewed-by: Mikulas Patocka

dm table: remove unused dm_get_device range parameters

2010-03-06T02:32:27+00:00

Remove unused parameters(start and len) of dm_get_device()
and fix the callers.

Signed-off-by: Nikanth Karthikesan 
Signed-off-by: Alasdair G Kergon

dm raid1: always return error if all legs fail

2010-03-06T02:32:22+00:00

If all mirror legs fail, always return an error instead of holding the
bio, even if the handle_errors option was set.  At present it is the
responsibility of the driver underneath us to deal with retries,
multipath etc.

The patch adds the bio to the failures list instead of holding it
directly.  do_failures tests first if all legs failed and, if so,
returns the bio with -EIO.  If any leg is still alive and handle_errors
is set, do_failures calls hold_bio.

Reviewed-by: Takahiro Yasui 
Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm raid1: fail writes if errors are not handled and log fails

2010-02-16T18:42:55+00:00

If the mirror log fails when the handle_errors option was not selected
and there is no remaining valid mirror leg, writes return success even
though they weren't actually written to any device.  This patch
completes them with EIO instead.

This code path is taken:
do_writes:
	bio_list_merge(&ms->failures, &sync);
do_failures:
	if (!get_valid_mirror(ms)) (false)
	else if (errors_handled(ms)) (false)
	else bio_endio(bio, 0);

The logic in do_failures is based on presuming that the write was already
tried: if it succeeded at least on one leg (without handle_errors) it
is reported as success.

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=555197

Signed-off-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm raid1: explicitly initialise bio_lists

2009-12-10T23:52:06+00:00

Explicitly initialize bio lists instead of relying on kzalloc.

Signed-off-by: Mikulas Patocka 
Reviewed-by: Takahiro Yasui 
Tested-by: Takahiro Yasui 
Signed-off-by: Alasdair G Kergon

dm raid1: hold all write bios when leg fails

2009-12-10T23:52:06+00:00

Hold all write bios when leg fails and errors are handled

When using a userspace daemon such as dmeventd to handle errors, we must
delay completing  bios until it has done its job.
This patch prevents the following race:
  - primary leg fails
  - write "1" fail, the write is held, secondary leg is set default
  - write "2" goes straight to the secondary leg

Signed-off-by: Mikulas Patocka 
Reviewed-by: Takahiro Yasui 
Tested-by: Takahiro Yasui 
Signed-off-by: Alasdair G Kergon

dm raid1: hold write bios when errors are handled

2009-12-10T23:52:05+00:00

Hold all write bios when errors are handled.

Previously the failures list was used only when handling errors with
a userspace daemon such as dmeventd.  Now, it is always used for all bios.
The regions where some writes failed must be marked as nosync. This can only
be done in process context (i.e. in raid1 workqueue), not in the
write_callback function.

Previously the write would succeed if writing to at least one leg
succeeded.  This is wrong because data from the failed leg may be
replicated to the correct leg.  Now, if using a userspace daemon, the
write with some failures will be held until the daemon has done its job
and reconfigured the array.  If not using a daemon, the write still
succeeds if at least one leg succeeds. This is bad, but it is consistent
with current behavior.

Signed-off-by: Mikulas Patocka 
Reviewed-by: Takahiro Yasui 
Tested-by: Takahiro Yasui 
Signed-off-by: Alasdair G Kergon

dm raid1: remove bio_endio from dm_rh_mark_nosync

2009-12-10T23:52:05+00:00

Move bio completion out of dm_rh_mark_nosync in preparation for the
next patch.

Signed-off-by: Mikulas Patocka 
Reviewed-by: Takahiro Yasui 
Tested-by: Takahiro Yasui 
Signed-off-by: Alasdair G Kergon

dm raid1: abstract get_valid_mirror function

2009-12-10T23:52:04+00:00

Move the logic to get a valid mirror leg into a function for re-use
in a later patch.

Signed-off-by: Mikulas Patocka 
Reviewed-by: Takahiro Yasui 
Tested-by: Takahiro Yasui 
Signed-off-by: Alasdair G Kergon

dm raid1: use hold framework in do_failures

2009-12-10T23:52:04+00:00

Use the hold framework in do_failures.

This patch doesn't change the bio processing logic, it just simplifies
failure handling and avoids periodically polling the failures list.

Signed-off-by: Mikulas Patocka 
Reviewed-by: Takahiro Yasui 
Tested-by: Takahiro Yasui 
Signed-off-by: Alasdair G Kergon