linux.git/drivers/md/dm-table.c, branch v3.12

dm ioctl: increase granularity of type_lock when loading table

2013-09-06T00:46:06+00:00

Hold the mapped device's type_lock before calling populate_table() since
it is where the table's type is determined based on the specified
targets.  There is no need to allow concurrent table loads to race to
establish the table's targets or type.

This eliminates the need to grab the lock in dm_table_set_type().

Also verify that the type_lock is held in both dm_set_md_type() and
dm_get_md_type().

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

dm: allow error target to replace bio-based and request-based targets

2013-09-06T00:46:05+00:00

It may be useful to switch a request-based table to the "error" target.
Enhance the DM core to allow a hybrid target_type which is capable of
handling either bios (via .map) or requests (via .map_rq).

Add a request-based map function (.map_rq) to the "error" target_type;
making it DM's first hybrid target.  Train dm_table_set_type() to prefer
the mapped device's established type (request-based or bio-based).  If
the mapped device doesn't have an established type default to making the
table with the hybrid target(s) bio-based.

Tested 'dmsetup wipe_table' to work on both bio-based and request-based
devices.

Signed-off-by: Mike Snitzer 
Signed-off-by: Joe Jin 
Signed-off-by: Jun'ichi Nomura 
Acked-by: Mikulas Patocka 
Signed-off-by: Alasdair G Kergon

dm: optimize use SRCU and RCU

2013-07-10T22:41:18+00:00

This patch removes "io_lock" and "map_lock" in struct mapped_device and
"holders" in struct dm_table and replaces these mechanisms with
sleepable-rcu.

Previously, the code would call "dm_get_live_table" and "dm_table_put" to
get and release table. Now, the code is changed to call "dm_get_live_table"
and "dm_put_live_table". dm_get_live_table locks sleepable-rcu and
dm_put_live_table unlocks it.

dm_get_live_table_fast/dm_put_live_table_fast can be used instead of
dm_get_live_table/dm_put_live_table. These *_fast functions use
non-sleepable RCU, so the caller must not block between them.

If the code changes active or inactive dm table, it must call
dm_sync_table before destroying the old table.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Jun'ichi Nomura 
Signed-off-by: Alasdair G Kergon

dm table: fix write same support

2013-05-10T13:37:16+00:00

If device_not_write_same_capable() returns true then the iterate_devices
loop in dm_table_supports_write_same() should return false.

Reported-by: Bharata B Rao 
Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org # v3.8+
Signed-off-by: Alasdair G Kergon

dm: rename request variables to bios

2013-03-01T22:45:47+00:00

Use 'bio' in the name of variables and functions that deal with
bios rather than 'request' to avoid confusion with the normal
block layer use of 'request'.

No functional changes.

Signed-off-by: Alasdair G Kergon

dm table: remove superfluous variable reset

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

If allocation fails, the local var *t is not used any more after kfree.
Don't need to reset it to NULL. Remove the unnecesary NULL set here.

Signed-off-by: Wang Sheng-Hui 
Signed-off-by: Alasdair G Kergon

dm: introduce per_bio_data

2012-12-21T20:23:38+00:00

Introduce a field per_bio_data_size in struct dm_target.

Targets can set this field in the constructor. If a target sets this
field to a non-zero value, "per_bio_data_size" bytes of auxiliary data
are allocated for each bio submitted to the target. These data can be
used for any purpose by the target and help us improve performance by
removing some per-target mempools.

Per-bio data is accessed with dm_per_bio_data. The
argument data_size must be the same as the value per_bio_data_size in
dm_target.

If the target has a pointer to per_bio_data, it can get a pointer to
the bio with dm_bio_from_per_bio_data() function (data_size must be the
same as the value passed to dm_per_bio_data).

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

dm: prepare to support WRITE SAME

2012-12-21T20:23:36+00:00

Allow targets to opt in to WRITE SAME support by setting
'num_write_same_requests' in the dm_target structure.

A dm device will only advertise WRITE SAME support if all its
targets and all its underlying devices support it.

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

dm: disable WRITE SAME

2012-12-21T20:23:30+00:00

WRITE SAME bios are not yet handled correctly by device-mapper so
disable their use on device-mapper devices by setting
max_write_same_sectors to zero.

As an example, a ciphertext device is incompatible because the data
gets changed according to the location at which it written and so the
dm crypt target cannot support it.

Signed-off-by: Mike Snitzer 
Cc: stable@vger.kernel.org
Cc: Milan Broz 
Signed-off-by: Alasdair G Kergon

dm: retain table limits when swapping to new table with no devices

2012-09-26T22:45:45+00:00

Add a safety net that will re-use the DM device's existing limits in the
event that DM device has a temporary table that doesn't have any
component devices.  This is to reduce the chance that requests not
respecting the hardware limits will reach the device.

DM recalculates queue limits based only on devices which currently exist
in the table.  This creates a problem in the event all devices are
temporarily removed such as all paths being lost in multipath.  DM will
reset the limits to the maximum permissible, which can then assemble
requests which exceed the limits of the paths when the paths are
restored.  The request will fail the blk_rq_check_limits() test when
sent to a path with lower limits, and will be retried without end by
multipath.  This became a much bigger issue after v3.6 commit fe86cdcef
("block: do not artificially constrain max_sectors for stacking
drivers").

Reported-by: David Jeffery 
Signed-off-by: Mike Snitzer 
Signed-off-by: Alasdair G Kergon