linux-stable.git/drivers/md/dm-table.c, branch v3.2.78

dm table: fail dm_table_create on dm_round_up overflow

2014-01-03T04:33:29+00:00

commit 5b2d06576c5410c10d95adfd5c4d8b24de861d87 upstream.

The dm_round_up function may overflow to zero.  In this case,
dm_table_create() must fail rather than go on to allocate an empty array
with alloc_targets().

This fixes a possible memory corruption that could be caused by passing
too large a number in "param->target_count".

Signed-off-by: Mikulas Patocka 
Signed-off-by: Mike Snitzer 
Signed-off-by: Ben Hutchings

dm: allocate buffer for messages with small number of arguments using GFP_NOIO

2014-01-03T04:33:16+00:00

commit f36afb3957353d2529cb2b00f78fdccd14fc5e9c upstream.

dm-mpath and dm-thin must process messages even if some device is
suspended, so we allocate argv buffer with GFP_NOIO. These messages have
a small fixed number of arguments.

On the other hand, dm-switch needs to process bulk data using messages
so excessive use of GFP_NOIO could cause trouble.

The patch also lowers the default number of arguments from 64 to 8, so
that there is smaller load on GFP_NOIO allocations.

Signed-off-by: Mikulas Patocka 
Acked-by: Alasdair G Kergon 
Signed-off-by: Mike Snitzer 
Signed-off-by: Ben Hutchings

dm table: clear add_random unless all devices have it set

2012-10-10T02:31:06+00:00

commit c3c4555edd10dbc0b388a0125b9c50de5e79af05 upstream.

Always clear QUEUE_FLAG_ADD_RANDOM if any underlying device does not
have it set. Otherwise devices with predictable characteristics may
contribute entropy.

QUEUE_FLAG_ADD_RANDOM specifies whether or not queue IO timings
contribute to the random pool.

For bio-based targets this flag is always 0 because such devices have no
real queue.

For request-based devices this flag was always set to 1 by default.

Now set it according to the flags on underlying devices. If there is at
least one device which should not contribute, set the flag to zero: If a
device, such as fast SSD storage, is not suitable for supplying entropy,
a request-based queue stacked over it will not be either.

Because the checking logic is exactly same as for the rotational flag,
share the iteration function with device_is_nonrot().

Signed-off-by: Milan Broz 
Signed-off-by: Alasdair G Kergon 
Signed-off-by: Ben Hutchings

dm table: add immutable feature

2011-10-31T20:19:04+00:00

Introduce DM_TARGET_IMMUTABLE to indicate that the target type cannot be mixed
with any other target type, and once loaded into a device, it cannot be
replaced with a table containing a different type.

The thin provisioning pool device will use this.

Signed-off-by: Alasdair G Kergon

dm table: add always writeable feature

2011-10-31T20:19:02+00:00

Add a target feature flag DM_TARGET_ALWAYS_WRITEABLE to indicate that a target
does not support read-only mode.

The initial implementation of the thin provisioning target uses this.

Signed-off-by: Alasdair G Kergon

dm table: add singleton feature

2011-10-31T20:19:00+00:00

Introduce the concept of a singleton table which contains exactly one target.

If a target type sets the DM_TARGET_SINGLETON feature bit device-mapper
will ensure that any table that includes that target contains no others.

The thin provisioning pool target uses this.

Signed-off-by: Alasdair G Kergon

dm table: propagate non rotational flag

2011-10-31T20:18:50+00:00

Allow QUEUE_FLAG_NONROT to propagate up the device stack if all
underlying devices are non-rotational.  Tools like ureadahead will
schedule IOs differently based on the rotational flag.

With this patch, I see boot time go from 7.75 s to 7.46 s on my device.

Suggested-by: J. Richard Barnette 
Signed-off-by: Mandeep Singh Baines 
Signed-off-by: Mike Snitzer 
Cc: Neil Brown 
Cc: Jens Axboe 
Cc: Martin K. Petersen 
Cc: dm-devel@redhat.com
Signed-off-by: Alasdair G Kergon

dm crypt: always disable discard_zeroes_data

2011-09-25T22:26:21+00:00

If optional discard support in dm-crypt is enabled, discards requests
bypass the crypt queue and blocks of the underlying device are discarded.
For the read path, discarded blocks are handled the same as normal
ciphertext blocks, thus decrypted.

So if the underlying device announces discarded regions return zeroes,
dm-crypt must disable this flag because after decryption there is just
random noise instead of zeroes.

Signed-off-by: Milan Broz 
Signed-off-by: Alasdair G Kergon

dm table: avoid crash if integrity profile changes

2011-09-25T22:26:17+00:00

Commit a63a5cf (dm: improve block integrity support) introduced a
two-phase initialization of a DM device's integrity profile.  This
patch avoids dereferencing a NULL 'template_disk' pointer in
blk_integrity_register() if there is an integrity profile mismatch in
dm_table_set_integrity().

This can occur if the integrity profiles for stacked devices in a DM
table are changed between the call to dm_table_prealloc_integrity() and
dm_table_set_integrity().

Reported-by: Zdenek Kabelac 
Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon 
Cc: stable@kernel.org # 2.6.39

dm table: set flush capability based on underlying devices

2011-08-02T11:32:08+00:00

DM has always advertised both REQ_FLUSH and REQ_FUA flush capabilities
regardless of whether or not a given DM device's underlying devices
also advertised a need for them.

Block's flush-merge changes from 2.6.39 have proven to be more costly
for DM devices.  Performance regressions have been reported even when
DM's underlying devices do not advertise that they have a write cache.

Fix the performance regressions by configuring a DM device's flushing
capabilities based on those of the underlying devices' capabilities.

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