linux.git/drivers/md, branch v3.9-rc1

dm cache: add cleaner policy

2013-03-01T22:45:52+00:00

A simple cache policy that writes back all data to the origin.

This is used to decommission a dm cache by emptying it.

Signed-off-by: Heinz Mauelshagen 
Signed-off-by: Joe Thornber 
Signed-off-by: Alasdair G Kergon

dm cache: add mq policy

2013-03-01T22:45:51+00:00

A cache policy that uses a multiqueue ordered by recent hit
count to select which blocks should be promoted and demoted.
This is meant to be a general purpose policy.  It prioritises
reads over writes.

Signed-off-by: Joe Thornber 
Signed-off-by: Alasdair G Kergon

dm: add cache target

2013-03-01T22:45:51+00:00

Add a target that allows a fast device such as an SSD to be used as a
cache for a slower device such as a disk.

A plug-in architecture was chosen so that the decisions about which data
to migrate and when are delegated to interchangeable tunable policy
modules.  The first general purpose module we have developed, called
"mq" (multiqueue), follows in the next patch.  Other modules are
under development.

Signed-off-by: Joe Thornber 
Signed-off-by: Heinz Mauelshagen 
Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon

dm persistent data: add bitset

2013-03-01T22:45:51+00:00

Add a persistent bitset as a wrapper around dm-array.

Signed-off-by: Joe Thornber 
Signed-off-by: Alasdair G Kergon

dm persistent data: add transactional array

2013-03-01T22:45:51+00:00

Add a transactional array.

Signed-off-by: Joe Thornber 
Signed-off-by: Alasdair G Kergon

dm thin: remove cells from stack

2013-03-01T22:45:50+00:00

This patch takes advantage of the new bio-prison interface where the
memory is now passed in rather than using a mempool in bio-prison.
This allows the map function to avoid performing potentially-blocking
allocations that could lead to deadlocks: We want to avoid the cell
allocation that is done in bio_detain.

(The potential for mempool deadlocks still remains in other functions
that use bio_detain.)

Signed-off-by: Joe Thornber 
Signed-off-by: Alasdair G Kergon

dm bio prison: pass cell memory in

2013-03-01T22:45:50+00:00

Change the dm_bio_prison interface so that instead of allocating memory
internally, dm_bio_detain is supplied with a pre-allocated cell each
time it is called.

This enables a subsequent patch to move the allocation of the struct
dm_bio_prison_cell outside the thin target's mapping function so it can
no longer block there.

Signed-off-by: Joe Thornber 
Signed-off-by: Alasdair G Kergon

dm persistent data: add btree_walk

2013-03-01T22:45:50+00:00

Add dm_btree_walk to iterate through the contents of a btree.
This will be used by the dm cache target.

Signed-off-by: Joe Thornber 
Signed-off-by: Alasdair G Kergon

dm: add target num_write_bios fn

2013-03-01T22:45:49+00:00

Add a num_write_bios function to struct target.

If an instance of a target sets this, it will be queried before the
target's mapping function is called on a write bio, and the response
controls the number of copies of the write bio that the target will
receive.

This provides a convenient way for a target to send the same data to
more than one device.  The new cache target uses this in writethrough
mode, to send the data both to the cache and the backing device.

Signed-off-by: Alasdair G Kergon

dm kcopyd: introduce configurable throttling

2013-03-01T22:45:49+00:00

This patch allows the administrator to reduce the rate at which kcopyd
issues I/O.

Each module that uses kcopyd acquires a throttle parameter that can be
set in /sys/module/*/parameters.

We maintain a history of kcopyd usage by each module in the variables
io_period and total_period in struct dm_kcopyd_throttle. The actual
kcopyd activity is calculated as a percentage of time equal to
"(100 * io_period / total_period)".  This is compared with the user-defined
throttle percentage threshold and if it is exceeded, we sleep.

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