linux-toradex.git/Documentation/device-mapper, branch v4.18-rc7

dm writecache: support optional offset for start of device

2018-07-02T20:14:02+00:00

Add an optional parameter "start_sector" to allow the start of the
device to be offset by the specified number of 512-byte sectors.  The
sectors below this offset are not used by the writecache device and are
left to be used for disk labels and/or userspace metadata (e.g. lvm).

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

dm: add writecache target

2018-06-08T15:59:51+00:00

The writecache target caches writes on persistent memory or SSD.
It is intended for databases or other programs that need extremely low
commit latency.

The writecache target doesn't cache reads because reads are supposed to
be cached in page cache in normal RAM.

If persistent memory isn't available this target can still be used in
SSD mode.

Signed-off-by: Mikulas Patocka 
Signed-off-by: Colin Ian King  # fix missing goto
Signed-off-by: Ross Zwisler  # fix compilation issue with !DAX
Signed-off-by: Dan Carpenter  # use msecs_to_jiffies
Acked-by: Dan Williams  # reworks to unify ARM and x86 flushing
Signed-off-by: Mike Snitzer

dm thin: update Documentation to clarify when "read_only" is valid

2018-05-10T15:18:49+00:00

Due to user confusion, clarify that it doesn't make sense to try to
create a thin-pool with "read_only" mode enabled.

Signed-off-by: Mike Snitzer

dm verity: add 'check_at_most_once' option to only validate hashes once

2018-04-03T19:04:29+00:00

This allows platforms that are CPU/memory contrained to verify data
blocks only the first time they are read from the data device, rather
than every time.  As such, it provides a reduced level of security
because only offline tampering of the data device's content will be
detected, not online tampering.

Hash blocks are still verified each time they are read from the hash
device, since verification of hash blocks is less performance critical
than data blocks, and a hash block will not be verified any more after
all the data blocks it covers have been verified anyway.

This option introduces a bitset that is used to check if a block has
been validated before or not.  A block can be validated more than once
as there is no thread protection for the bitset.

These changes were developed and tested on entry-level Android Go
devices.

Signed-off-by: Patrik Torstensson 
Signed-off-by: Mike Snitzer

dm cache: Documentation: update default migration_throttling value

2018-01-30T21:55:47+00:00

In commit f8350daf7af0 ("dm cache: tune migration throttling") the
value for DEFAULT_MIGRATION_THRESHOLD was decreased from 204800 to
2048.  Edit device-mapper/cache.txt to reflect the correct default
value for migration_threshold.

Signed-off-by: John Pittman 
Signed-off-by: Mike Snitzer

dm thin: extend thinpool status format string with omitted fields

2018-01-17T14:16:12+00:00

Signed-off-by: mulhern 
Signed-off-by: Mike Snitzer

dm thin: fixes in thin-provisioning.txt

2018-01-17T14:16:12+00:00

Make the format string for thinpool status more correct.

Swap the order of two items to correspond with reality.

Signed-off-by: mulhern 
Signed-off-by: Mike Snitzer

dm thin: document representation of when there is none

2018-01-17T14:16:11+00:00

Signed-off-by: mulhern 
Signed-off-by: Mike Snitzer

dm thin: fix documentation relative to low water mark threshold

2018-01-17T14:16:10+00:00

Fixes:
1. The use of "exceeds" when the opposite of exceeds, falls below,
was meant.
2. Properly speaking, a table can not exceed a threshold.

It emphasizes the important point, which is that it is the userspace
daemon's responsibility to check for low free space when a device
is resumed, since it won't get a special event indicating low free
space in that situation.

Signed-off-by: mulhern 
Signed-off-by: Mike Snitzer

dm cache: be consistent in specifying sectors and SI units in cache.txt

2018-01-17T14:16:09+00:00

Signed-off-by: mulhern 
Signed-off-by: Mike Snitzer