linux/Documentation/device-mapper, branch v3.4.83

dm: verity fix documentation

2012-07-16T16:04:25Z

commit 18068bdd5f59229623b2fa518a6389e346642b0d upstream. Veritysetup is now part of cryptsetup package. Remove on-disk header description (which is not parsed in kernel) and point users to cryptsetup where it the format is documented. Mention units for block size paramaters. Fix target line specification and dmsetup parameters. Signed-off-by: Milan Broz Signed-off-by: Alasdair G Kergon Signed-off-by: Greg Kroah-Hartman

dm: add verity target

2012-03-28T17:43:38Z

This device-mapper target creates a read-only device that transparently validates the data on one underlying device against a pre-generated tree of cryptographic checksums stored on a second device. Two checksum device formats are supported: version 0 which is already shipping in Chromium OS and version 1 which incorporates some improvements. Signed-off-by: Mikulas Patocka Signed-off-by: Mandeep Singh Baines Signed-off-by: Will Drewry Signed-off-by: Elly Jones Cc: Milan Broz Cc: Olof Johansson Cc: Steffen Klassert Cc: Andrew Morton Signed-off-by: Alasdair G Kergon

dm thin: add pool target flags to control discard

2012-03-28T17:41:29Z

Add dm thin target arguments to control discard support. ignore_discard: Disables discard support no_discard_passdown: Don't pass discards down to the underlying data device, but just remove the mapping within the thin provisioning target. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm thin: support read only external snapshot origins

2012-03-28T17:41:28Z

Support the use of an external _read only_ device as an origin for a thin device. Any read to an unprovisioned area of the thin device will be passed through to the origin. Writes trigger allocation of new blocks as usual. One possible use case for this would be VM hosts that want to run guests on thinly-provisioned volumes but have the base image on another device (possibly shared between many VMs). Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm thin: relax hard limit on the maximum size of a metadata device

2012-03-28T17:41:28Z

The thin metadata format can only make use of a device that is <= THIN_METADATA_MAX_SECTORS (currently 15.9375 GB). Therefore, there is no practical benefit to using a larger device. However, it may be that other factors impose a certain granularity for the space that is allocated to a device (E.g. lvm2 can impose a coarse granularity through the use of large, >= 1 GB, physical extents). Rather than reject a larger metadata device, during thin-pool device construction, switch to allowing it but issue a warning if a device larger than THIN_METADATA_MAX_SECTORS_WARNING (16 GB) is provided. Any space over 15.9375 GB will not be used. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

dm thin: correct comments

2012-03-28T17:41:24Z

Remove documentation for unimplemented 'trim' message. I'd planned a 'trim' target message for shrinking thin devices, but this is better handled via the discard ioctl. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon

Documentation: Fix multiple typo in Documentation

2012-03-07T15:08:24Z

Signed-off-by: Masanari Iida Acked-by: Randy Dunlap Signed-off-by: Jiri Kosina

Documentation: Fix typo in thin-provisioning.txt

2012-02-21T10:40:37Z

Correct spelling "descibes" to "describes" in Documentation/device-mapper/thin-provisioning.txt Signed-off-by: Masanari Iida Signed-off-by: Jiri Kosina

dm log userspace: fix comment hyphens

2011-10-31T20:21:22Z

Fix comments: clustered-disk needs a hyphen not an underscore. Signed-off-by: Jonathan Brassow Signed-off-by: Alasdair G Kergon

dm: add thin provisioning target

2011-10-31T20:21:18Z

Initial EXPERIMENTAL implementation of device-mapper thin provisioning with snapshot support. The 'thin' target is used to create instances of the virtual devices that are hosted in the 'thin-pool' target. The thin-pool target provides data sharing among devices. This sharing is made possible using the persistent-data library in the previous patch. The main highlight of this implementation, compared to the previous implementation of snapshots, is that it allows many virtual devices to be stored on the same data volume, simplifying administration and allowing sharing of data between volumes (thus reducing disk usage). Another big feature is support for arbitrary depth of recursive snapshots (snapshots of snapshots of snapshots ...). The previous implementation of snapshots did this by chaining together lookup tables, and so performance was O(depth). This new implementation uses a single data structure so we don't get this degradation with depth. For further information and examples of how to use this, please read Documentation/device-mapper/thin-provisioning.txt Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon