linux-toradex.git/drivers/md/dm-table.c, branch v3.4.99

dm table: fail dm_table_create on dm_round_up overflow

2013-12-20T15:34:20+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: Greg Kroah-Hartman

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

2013-12-04T18:50:31+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: Greg Kroah-Hartman

dm table: clear add_random unless all devices have it set

2012-10-07T15:32:22+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: Greg Kroah-Hartman

dm: reject trailing characters in sccanf input

2012-03-28T17:41:26+00:00

Device mapper uses sscanf to convert arguments to numbers. The problem is that
the way we use it ignores additional unmatched characters in the scanned string.

For example, this `if (sscanf(string, "%d", &number) == 1)' will match a number,
but also it will match number with some garbage appended, like "123abc".

As a result, device mapper accepts garbage after some numbers. For example
the command `dmsetup create vg1-new --table "0 16384 linear 254:1bla 34816bla"'
will pass without an error.

This patch fixes all sscanf uses in device mapper. It appends "%c" with
a pointer to a dummy character variable to every sscanf statement.

The construct `if (sscanf(string, "%d%c", &number, &dummy) == 1)' succeeds
only if string is a null-terminated number (optionally preceded by some
whitespace characters). If there is some character appended after the number,
sscanf matches "%c", writes the character to the dummy variable and returns 2.
We check the return value for 1 and consequently reject numbers with some
garbage appended.

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

dm table: simplify call to free_devices

2012-03-28T17:41:24+00:00

free_devices in dm_table.c already uses list_for_each(), so we don't
need to check if the list is empty.

Signed-off-by: Hannes Reinecke 
Signed-off-by: Alasdair G Kergon

block: Introduce blk_set_stacking_limits function

2012-01-11T15:27:11+00:00

Stacking driver queue limits are typically bounded exclusively by the
capabilities of the low level devices, not by the stacking driver
itself.

This patch introduces blk_set_stacking_limits() which has more liberal
metrics than the default queue limits function. This allows us to
inherit topology parameters from bottom devices without manually
tweaking the default limits in each driver prior to calling the stacking
function.

Since there is now a clear distinction between stacking and low-level
devices, blk_set_default_limits() has been modified to carry the more
conservative values that we used to manually set in
blk_queue_make_request().

Signed-off-by: Martin K. Petersen 
Acked-by: Mike Snitzer 
Signed-off-by: Jens Axboe

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