linux-stable.git/drivers/md/dm-raid.c, branch linux-3.7.y

DM-RAID: Fix RAID10's check for sufficient redundancy

2013-02-04T00:27:02+00:00

commit 55ebbb59c1c6eb1b040f62b8c4ae0b724de6e55a upstream.

Before attempting to activate a RAID array, it is checked for sufficient
redundancy.  That is, we make sure that there are not too many failed
devices - or devices specified for rebuild - to undermine our ability to
activate the array.  The current code performs this check twice - once to
ensure there were not too many devices specified for rebuild by the user
('validate_rebuild_devices') and again after possibly experiencing a failure
to read the superblock ('analyse_superblocks').  Neither of these checks are
sufficient.  The first check is done properly but with insufficient
information about the possible failure state of the devices to make a good
determination if the array can be activated.  The second check is simply
done wrong in the case of RAID10 because it doesn't account for the
independence of the stripes (i.e. mirror sets).  The solution is to use the
properly written check ('validate_rebuild_devices'), but perform the check
after the superblocks have been read and we know which devices have failed.
This gives us one check instead of two and performs it in a location where
it can be done right.

Only RAID10 was affected and it was affected in the following ways:
- the code did not properly catch the condition where a user specified
  a device for rebuild that already had a failed device in the same mirror
  set.  (This condition would, however, be caught at a deeper level in MD.)
- the code triggers a false positive and denies activation when devices in
  independent mirror sets have failed - counting the failures as though they
  were all in the same set.

The most likely place this error was introduced (or this patch should have
been included) is in commit 4ec1e369 - first introduced in v3.7-rc1.
Consequently this fix should also go in v3.7.y, however there is a
small conflict on the .version in raid_target, so I'll submit a
separate patch to -stable.

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

DM RAID: Fix for "sync" directive ineffectiveness

2012-10-11T02:42:19+00:00

There are two table arguments that can be given to a DM RAID target
that control whether the array is forced to (re)synchronize or skip
initialization: "sync" and "nosync".  When "sync" is given, we set
mddev->recovery_cp to 0 in order to cause the device to resynchronize.
This is insufficient if there is a bitmap in use, because the array
will simply look at the bitmap and see that there is no recovery
necessary.

The fix is to skip over the loading of the superblocks when "sync" is
given, causing new superblocks to be written that will force the array
to go through initialization (i.e. synchronization).

Signed-off-by: Jonathan Brassow 
Signed-off-by: NeilBrown

DM RAID: Fix comparison of index and quantity for "rebuild" parameter

2012-10-11T02:40:36+00:00

DM RAID: Fix comparison of index and quantity for "rebuild" parameter

The "rebuild" parameter takes an index argument that starts counting from
zero.  The conditional used to validate the index was using '>' rather than
'>=', leaving the door open for an index value that would be 1 too large.

Reported-by: Neil Brown 
Signed-off-by: Jonathan Brassow 
Signed-off-by: NeilBrown

DM RAID: Add rebuild capability for RAID10

2012-10-11T02:40:24+00:00

DM RAID:  Add code to validate replacement slots for RAID10 arrays

RAID10 can handle 'copies - 1' failures for each mirror group.  This code
ensures the user has provided a valid array - one whose devices specified for
rebuild do not exceed the amount of redundancy available.

Signed-off-by: Jonathan Brassow 
Signed-off-by: NeilBrown

DM RAID: Move 'rebuild' checking code to its own function

2012-10-11T02:40:09+00:00

DM RAID:  Move chunk of code to it's own function

The code that checks whether device replacements/rebuilds are possible given
a specific RAID type is moved to it's own function.  It will further expand
when the code to check RAID10 is added.  A separate function makes it easier
to read.

Signed-off-by: Jonathan Brassow 
Signed-off-by: NeilBrown

Merge branch 'for-next' of git://neil.brown.name/md

2012-08-01T16:02:01+00:00

Pull md updates from NeilBrown.

* 'for-next' of git://neil.brown.name/md:
  DM RAID: Add support for MD RAID10
  md/RAID1: Add missing case for attempting to repair known bad blocks.
  md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE.
  md/raid1: don't abort a resync on the first badblock.
  md: remove duplicated test on ->openers when calling do_md_stop()
  raid5: Add R5_ReadNoMerge flag which prevent bio from merging at block layer
  md/raid1: prevent merging too large request
  md/raid1: read balance chooses idlest disk for SSD
  md/raid1: make sequential read detection per disk based
  MD RAID10: Export md_raid10_congested
  MD: Move macros from raid1*.h to raid1*.c
  MD RAID1: rename mirror_info structure
  MD RAID10: rename mirror_info structure
  MD RAID10: Fix compiler warning.
  raid5: add a per-stripe lock
  raid5: remove unnecessary bitmap write optimization
  raid5: lockless access raid5 overrided bi_phys_segments
  raid5: reduce chance release_stripe() taking device_lock

DM RAID: Add support for MD RAID10

2012-08-01T10:41:20+00:00

Support the MD RAID10 personality through dm-raid.c

Signed-off-by: Jonathan Brassow 
Signed-off-by: NeilBrown

dm thin: commit before gathering status

2012-07-27T14:08:16+00:00

Commit outstanding metadata before returning the status for a dm thin
pool so that the numbers reported are as up-to-date as possible.

The commit is not performed if the device is suspended or if
the DM_NOFLUSH_FLAG is supplied by userspace and passed to the target
through a new 'status_flags' parameter in the target's dm_status_fn.

The userspace dmsetup tool will support the --noflush flag with the
'dmsetup status' and 'dmsetup wait' commands from version 1.02.76
onwards.

Tested-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm raid: move sectors_per_dev calculation

2012-07-27T14:08:04+00:00

In preparation for RAID10 inclusion in dm-raid, we move the sectors_per_dev
calculation later in the device creation process.  This is because we won't
know up-front how many stripes vs how many mirrors there are which will
change the calculation.

Signed-off-by: Jonathan Brassow 
Signed-off-by: Alasdair G Kergon

dm raid: restructure parse_raid_params

2012-07-27T14:08:04+00:00

In preparation for RAID10 addition to dm-raid, we change an 'if' conditional
to a 'switch' conditional to make it easier to see what is being checked for
each RAID type.

Signed-off-by: Jonathan Brassow 
Signed-off-by: Alasdair G Kergon