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DM RAID: Add message/status support for changing sync action
This patch adds a message interface to dm-raid to allow the user to more
finely control the sync actions being performed by the MD driver. This
gives the user the ability to initiate "check" and "repair" (i.e. scrubbing).
Two additional fields have been appended to the status output to provide more
information about the type of sync action occurring and the results of those
actions, specifically: <sync_action> and <mismatch_cnt>. These new fields
will always be populated. This is essentially the device-mapper way of doing
what MD controls through the 'sync_action' sysfs file and shows through the
'mismatch_cnt' sysfs file.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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Pull md updates from NeilBrown:
"Mostly little bugfixes.
Only "feature" is a new RAID10 layout which slightly improves the
number of sets of devices that can concurrently fail, without data
loss."
* tag 'md-3.9' of git://neil.brown.name/md:
md: expedite metadata update when switching read-auto -> active
md: remove CONFIG_MULTICORE_RAID456
md/raid1,raid10: fix deadlock with freeze_array()
md/raid0: improve error message when converting RAID4-with-spares to RAID0
md: raid0: fix error return from create_stripe_zones.
md: fix two bugs when attempting to resize RAID0 array.
DM RAID: Add support for MD's RAID10 "far" and "offset" algorithms
MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 2)
MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 1)
MD RAID10: Minor non-functional code changes
md: raid1,10: Handle REQ_WRITE_SAME flag in write bios
md: protect against crash upon fsync on ro array
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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 <mauelshagen@redhat.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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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 <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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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 <ejt@redhat.com>
Signed-off-by: Heinz Mauelshagen <mauelshagen@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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DM RAID: Add support for MD's RAID10 "far" and "offset" algorithms
Until now, dm-raid.c only supported the "near" algorthm of MD's RAID10
implementation. This patch adds support for the "far" and "offset"
algorithms, but only with the improved redundancy that is brought with
the introduction of the 'use_far_sets' bit, which shifts copied stripes
according to smaller sets vs the entire array. That is, the 17th bit
of the 'layout' variable that defines the RAID10 implementation will
always be set. (More information on how the 'layout' variable selects
the RAID10 algorithm can be found in the opening comments of
drivers/md/raid10.c.)
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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Before attempting to activate a RAID array, it is checked for sufficient
redundancy. That is, we make sure that there are not too many failed
devices - or devices specified for rebuild - to undermine our ability to
activate the array. The current code performs this check twice - once to
ensure there were not too many devices specified for rebuild by the user
('validate_rebuild_devices') and again after possibly experiencing a failure
to read the superblock ('analyse_superblocks'). Neither of these checks are
sufficient. The first check is done properly but with insufficient
information about the possible failure state of the devices to make a good
determination if the array can be activated. The second check is simply
done wrong in the case of RAID10 because it doesn't account for the
independence of the stripes (i.e. mirror sets). The solution is to use the
properly written check ('validate_rebuild_devices'), but perform the check
after the superblocks have been read and we know which devices have failed.
This gives us one check instead of two and performs it in a location where
it can be done right.
Only RAID10 was affected and it was affected in the following ways:
- the code did not properly catch the condition where a user specified
a device for rebuild that already had a failed device in the same mirror
set. (This condition would, however, be caught at a deeper level in MD.)
- the code triggers a false positive and denies activation when devices in
independent mirror sets have failed - counting the failures as though they
were all in the same set.
The most likely place this error was introduced (or this patch should have
been included) is in commit 4ec1e369 - first introduced in v3.7-rc1.
Consequently this fix should also go in v3.7.y, however there is a
small conflict on the .version in raid_target, so I'll submit a
separate patch to -stable.
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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DM RAID: Add code to validate replacement slots for RAID10 arrays
RAID10 can handle 'copies - 1' failures for each mirror group. This code
ensures the user has provided a valid array - one whose devices specified for
rebuild do not exceed the amount of redundancy available.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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Pull md updates from NeilBrown.
* 'for-next' of git://neil.brown.name/md:
DM RAID: Add support for MD RAID10
md/RAID1: Add missing case for attempting to repair known bad blocks.
md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE.
md/raid1: don't abort a resync on the first badblock.
md: remove duplicated test on ->openers when calling do_md_stop()
raid5: Add R5_ReadNoMerge flag which prevent bio from merging at block layer
md/raid1: prevent merging too large request
md/raid1: read balance chooses idlest disk for SSD
md/raid1: make sequential read detection per disk based
MD RAID10: Export md_raid10_congested
MD: Move macros from raid1*.h to raid1*.c
MD RAID1: rename mirror_info structure
MD RAID10: rename mirror_info structure
MD RAID10: Fix compiler warning.
raid5: add a per-stripe lock
raid5: remove unnecessary bitmap write optimization
raid5: lockless access raid5 overrided bi_phys_segments
raid5: reduce chance release_stripe() taking device_lock
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Support the MD RAID10 personality through dm-raid.c
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
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Add read-only and fail-io modes to thin provisioning.
If a transaction commit fails the pool's metadata device will transition
to "read-only" mode. If a commit fails once already in read-only mode
the transition to "fail-io" mode occurs.
Once in fail-io mode the pool and all associated thin devices will
report a status of "Fail".
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Support non-power-of-2 chunk sizes with dm striping for proper alignment
of stripe IO on storage that has non-power-of-2 optimal IO sizes (e.g.
RAID6 10+2).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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dm-stripe is supposed to ensure that all the space allocated to the
stripes is fully used and that all stripes are the same size. This
patch fixes the test. It checks that device length is divisible by the
chunk size and checks that the resulting quotient is divisible by the
number of stripes (which is equivalent to testing if device length is
divisible by chunk_size * stripes).
Previously, the code only tested that the number of sectors in the target
was divisible by each of the chunk size and the number of stripes
separately, which could leave entire stripes unused.
(A setup that genuinely needs some stripes to be shorter than others
can be created by concatenating striped targets.)
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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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 <mbroz@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch implements two new messages that can be sent to the thin
pool target allowing it to take a snapshot of the _metadata_. This,
read-only snapshot can be accessed by userland, concurrently with the
live target.
Only one metadata snapshot can be held at a time. The pool's status
line will give the block location for the current msnap.
Since version 0.1.5 of the userland thin provisioning tools, the
thin_dump program displays the msnap as follows:
thin_dump -m <msnap root> <metadata dev>
Available here: https://github.com/jthornber/thin-provisioning-tools
Now that userland can access the metadata we can do various things
that have traditionally been kernel side tasks:
i) Incremental backups.
By using metadata snapshots we can work out what blocks have
changed over time. Combined with data snapshots we can ensure
the data doesn't change while we back it up.
A short proof of concept script can be found here:
https://github.com/jthornber/thinp-test-suite/blob/master/incremental_backup_example.rb
ii) Migration of thin devices from one pool to another.
iii) Merging snapshots back into an external origin.
iv) Asyncronous replication.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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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 <mpatocka@redhat.com>
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Signed-off-by: Will Drewry <wad@chromium.org>
Signed-off-by: Elly Jones <ellyjones@chromium.org>
Cc: Milan Broz <mbroz@redhat.com>
Cc: Olof Johansson <olofj@chromium.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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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 <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Correct spelling "descibes" to "describes" in
Documentation/device-mapper/thin-provisioning.txt
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Fix comments: clustered-disk needs a hyphen not an underscore.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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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 <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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The persistent-data library offers a re-usable framework for the storage
and management of on-disk metadata in device-mapper targets.
It's used by the thin-provisioning target in the next patch and in an
upcoming hierarchical storage target.
For further information, please read
Documentation/device-mapper/persistent-data.txt
Signed-off-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Add optional parameter field to dmcrypt table and support
"allow_discards" option.
Discard requests bypass crypt queue processing. Bio is simple remapped
to underlying device.
Note that discard will be never enabled by default because of security
consequences. It is up to the administrator to enable it for encrypted
devices.
(Note that userspace cryptsetup does not understand new optional
parameters yet. Support for this will come later. Until then, you
should use 'dmsetup' to enable and disable this.)
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Add the ability to parse and use metadata devices to dm-raid. Although
not strictly required, without the metadata devices, many features of
RAID are unavailable. They are used to store a superblock and bitmap.
The role, or position in the array, of each device must be recorded in
its superblock. This is to help with fault handling, array reshaping,
and sanity checks. RAID 4/5/6 devices must be loaded in a specific order:
in this way, the 'array_position' field helps validate the correctness
of the mapping when it is loaded. It can be used during reshaping to
identify which devices are added/removed. Fault handling is impossible
without this field. For example, when a device fails it is recorded in
the superblock. If this is a RAID1 device and the offending device is
removed from the array, there must be a way during subsequent array
assembly to determine that the failed device was the one removed. This
is done by correlating the 'array_position' field and the bit-field
variable 'failed_devices'.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Add the write_mostly parameter to RAID1 dm-raid tables.
This allows the user to set the WriteMostly flag on a RAID1 device that
should normally be avoided for read I/O.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Allow the user to specify the region_size.
Ensures that the supplied value meets md's constraints, viz. the number of
regions does not exceed 2^21.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Add more information about some dm-raid table parameters and clarify how
parameters are printed when 'dmsetup table' is issued.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Add corrupt_bio_byte feature to simulate corruption by overwriting a byte at a
specified position with a specified value during intervals when the device is
"down".
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Add 'drop_writes' option to drop writes silently while the
device is 'down'. Reads are not touched.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
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This target is the same as the linear target except that it returns I/O
errors periodically. It's been found useful in simulating failing
devices for testing purposes.
I needed a dm target to do some failure testing on btrfs's raid code, and
Mike pointed me at this.
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Acked-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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This patch is the skeleton for the DM target that will be
the bridge from DM to MD (initially RAID456 and later RAID1). It
provides a way to use device-mapper interfaces to the MD RAID456
drivers.
As with all device-mapper targets, the nominal public interfaces are the
constructor (CTR) tables and the status outputs (both STATUSTYPE_INFO
and STATUSTYPE_TABLE). The CTR table looks like the following:
1: <s> <l> raid \
2: <raid_type> <#raid_params> <raid_params> \
3: <#raid_devs> <meta_dev1> <dev1> .. <meta_devN> <devN>
Line 1 contains the standard first three arguments to any device-mapper
target - the start, length, and target type fields. The target type in
this case is "raid".
Line 2 contains the arguments that define the particular raid
type/personality/level, the required arguments for that raid type, and
any optional arguments. Possible raid types include: raid4, raid5_la,
raid5_ls, raid5_rs, raid6_zr, raid6_nr, and raid6_nc. (again, raid1 is
planned for the future.) The list of required and optional parameters
is the same for all the current raid types. The required parameters are
positional, while the optional parameters are given as key/value pairs.
The possible parameters are as follows:
<chunk_size> Chunk size in sectors.
[[no]sync] Force/Prevent RAID initialization
[rebuild <idx>] Rebuild the drive indicated by the index
[daemon_sleep <ms>] Time between bitmap daemon work to clear bits
[min_recovery_rate <kB/sec/disk>] Throttle RAID initialization
[max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
[max_write_behind <value>] See '-write-behind=' (man mdadm)
[stripe_cache <sectors>] Stripe cache size for higher RAIDs
Line 3 contains the list of devices that compose the array in
metadata/data device pairs. If the metadata is stored separately, a '-'
is given for the metadata device position. If a drive has failed or is
missing at creation time, a '-' can be given for both the metadata and
data drives for a given position.
Examples:
# RAID4 - 4 data drives, 1 parity
# No metadata devices specified to hold superblock/bitmap info
# Chunk size of 1MiB
# (Lines separated for easy reading)
0 1960893648 raid \
raid4 1 2048 \
5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
# RAID4 - 4 data drives, 1 parity (no metadata devices)
# Chunk size of 1MiB, force RAID initialization,
# min recovery rate at 20 kiB/sec/disk
0 1960893648 raid \
raid4 4 2048 min_recovery_rate 20 sync\
5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81
Performing a 'dmsetup table' should display the CTR table used to
construct the mapping (with possible reordering of optional
parameters).
Performing a 'dmsetup status' will yield information on the state and
health of the array. The output is as follows:
1: <s> <l> raid \
2: <raid_type> <#devices> <1 health char for each dev> <resync_ratio>
Line 1 is standard DM output. Line 2 is best shown by example:
0 1960893648 raid raid4 5 AAAAA 2/490221568
Here we can see the RAID type is raid4, there are 5 devices - all of
which are 'A'live, and the array is 2/490221568 complete with recovery.
Cc: linux-raid@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch adds generic multikey handling to be used
in following patch for Loop-AES mode compatibility.
This patch extends mapping table to optional keycount and
implements generic multi-key capability.
With more keys defined the <key> string is divided into
several <keycount> sections and these are used for tfms.
The tfm is used according to sector offset
(sector 0->tfm[0], sector 1->tfm[1], sector N->tfm[N modulo keycount])
(only power of two values supported for keycount here).
Because of tfms per-cpu allocation, this mode can be take
a lot of memory on large smp systems.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Max Vozeler <max@hinterhof.net>
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Below you will find an updated version from the original series bunching all patches into one big patch
updating broken web addresses that are located in Documentation/*
Some of the addresses date as far far back as 1995 etc... so searching became a bit difficult,
the best way to deal with these is to use web.archive.org to locate these addresses that are outdated.
Now there are also some addresses pointing to .spec files some are located, but some(after searching
on the companies site)where still no where to be found. In this case I just changed the address
to the company site this way the users can contact the company and they can locate them for the users.
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Thomas Weber <weber@corscience.de>
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Cc: Paulo Marques <pmarques@grupopie.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Michael Neuling <mikey@neuling.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Update Documentation/device-mapper/snapshot.txt to cover "How to
determine when a snapshot has finished merging".
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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The snapshot-merge target allows a snapshot to be merged back into the
snapshot's origin device.
One anticipated use of snapshot merging is the rollback of filesystems
to back out problematic system upgrades.
This patch adds snapshot-merge target management to both
dm_snapshot_init() and dm_snapshot_exit(). As an initial place-holder,
snapshot-merge is identical to the snapshot target. Documentation is
provided.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch contains a device-mapper mirror log module that forwards
requests to userspace for processing.
The structures used for communication between kernel and userspace are
located in include/linux/dm-log-userspace.h. Due to the frequency,
diversity, and 2-way communication nature of the exchanges between
kernel and userspace, 'connector' was chosen as the interface for
communication.
The first log implementations written in userspace - "clustered-disk"
and "clustered-core" - support clustered shared storage. A userspace
daemon (in the LVM2 source code repository) uses openAIS/corosync to
process requests in an ordered fashion with the rest of the nodes in the
cluster so as to prevent log state corruption. Other implementations
with no association to LVM or openAIS/corosync, are certainly possible.
(Imagine if two machines are writing to the same region of a mirror.
They would both mark the region dirty, but you need a cluster-aware
entity that can handle properly marking the region clean when they are
done. Otherwise, you might clear the region when the first machine is
done, not the second.)
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch adds a service time oriented dynamic load balancer,
dm-service-time, which selects the path with the shortest estimated
service time for the incoming I/O.
The service time is estimated by dividing the in-flight I/O size
by a performance value of each path.
The performance value can be given as a table argument at the table
loading time. If no performance value is given, all paths are
considered equal.
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch adds a dynamic load balancer, dm-queue-length, which
balances the number of in-flight I/Os across the paths.
The code is based on the patch posted by Stefan Bader:
https://www.redhat.com/archives/dm-devel/2005-October/msg00050.html
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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Add description of dm-crypt to device-mapper documentation.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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This patch adds support for the dm_path_event dm_send_event functions which
create and send udev events.
Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
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New device-mapper target that can delay I/O (for testing). Reads can be
separated from writes, redirected to different underlying devices and delayed
by differing amounts of time.
Signed-off-by: Heinz Mauelshagen <mauelshagen@redhat.com>
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I've recently added this documentation, Alasdair gave some corrections, and
here are some further corrections on top of his work (partly style issue,
partly a technical error due to different past experience, partly a note
which I've added - i.e. transient snapshots are lighter).
Cc: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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I've recently discovered the real functionality of device-mapper snapshots,
and since they are not well known, I've decided to write some docs for
them.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
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