11 Jun, 2016
1 commit
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Add some seperation between bio-based and request-based DM core code.
'struct mapped_device' and other DM core only structures and functions
have been moved to dm-core.h and all relevant DM core .c files have been
updated to include dm-core.h rather than dm.hDM targets should _never_ include dm-core.h!
[block core merge conflict resolution from Stephen Rothwell]
Signed-off-by: Mike Snitzer
Signed-off-by: Stephen Rothwell
11 Mar, 2016
1 commit
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smq seems to be performing better than the old mq policy in all
situations, as well as using a quarter of the memory.Make 'mq' an alias for 'smq' when choosing a cache policy. The tunables
that were present for the old mq are faked, and have no effect. mq
should be considered deprecated now.Signed-off-by: Joe Thornber
Signed-off-by: Mike Snitzer
10 Dec, 2015
2 commits
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Add support for correcting corrupted blocks using Reed-Solomon.
This code uses RS(255, N) interleaved across data and hash
blocks. Each error-correcting block covers N bytes evenly
distributed across the combined total data, so that each byte is a
maximum distance away from the others. This makes it possible to
recover from several consecutive corrupted blocks with relatively
small space overhead.In addition, using verity hashes to locate erasures nearly doubles
the effectiveness of error correction. Being able to detect
corrupted blocks also improves performance, because only corrupted
blocks need to corrected.For a 2 GiB partition, RS(255, 253) (two parity bytes for each
253-byte block) can correct up to 16 MiB of consecutive corrupted
blocks if erasures can be located, and 8 MiB if they cannot, with
16 MiB space overhead.Signed-off-by: Sami Tolvanen
Signed-off-by: Mike Snitzer -
Prepare for extending dm-verity with an optional object. Follows the
naming convention used by other DM targets (e.g. dm-cache and dm-era).Signed-off-by: Sami Tolvanen
Signed-off-by: Mike Snitzer
24 Oct, 2015
1 commit
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This introduces a simple log for raid5. Data/parity writing to raid
array first writes to the log, then write to raid array disks. If
crash happens, we can recovery data from the log. This can speed up
raid resync and fix write hole issue.The log structure is pretty simple. Data/meta data is stored in block
unit, which is 4k generally. It has only one type of meta data block.
The meta data block can track 3 types of data, stripe data, stripe
parity and flush block. MD superblock will point to the last valid
meta data block. Each meta data block has checksum/seq number, so
recovery can scan the log correctly. We store a checksum of stripe
data/parity to the metadata block, so meta data and stripe data/parity
can be written to log disk together. otherwise, meta data write must
wait till stripe data/parity is finished.For stripe data, meta data block will record stripe data sector and
size. Currently the size is always 4k. This meta data record can be made
simpler if we just fix write hole (eg, we can record data of a stripe's
different disks together), but this format can be extended to support
caching in the future, which must record data address/size.For stripe parity, meta data block will record stripe sector. It's
size should be 4k (for raid5) or 8k (for raid6). We always store p
parity first. This format should work for caching too.flush block indicates a stripe is in raid array disks. Fixing write
hole doesn't need this type of meta data, it's for caching extension.Signed-off-by: Shaohua Li
Signed-off-by: NeilBrown
12 Jun, 2015
1 commit
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The stochastic-multi-queue (smq) policy addresses some of the problems
with the current multiqueue (mq) policy.Memory usage
------------The mq policy uses a lot of memory; 88 bytes per cache block on a 64
bit machine.SMQ uses 28bit indexes to implement it's data structures rather than
pointers. It avoids storing an explicit hit count for each block. It
has a 'hotspot' queue rather than a pre cache which uses a quarter of
the entries (each hotspot block covers a larger area than a single
cache block).All these mean smq uses ~25bytes per cache block. Still a lot of
memory, but a substantial improvement nontheless.Level balancing
---------------MQ places entries in different levels of the multiqueue structures
based on their hit count (~ln(hit count)). This means the bottom
levels generally have the most entries, and the top ones have very
few. Having unbalanced levels like this reduces the efficacy of the
multiqueue.SMQ does not maintain a hit count, instead it swaps hit entries with
the least recently used entry from the level above. The over all
ordering being a side effect of this stochastic process. With this
scheme we can decide how many entries occupy each multiqueue level,
resulting in better promotion/demotion decisions.Adaptability
------------The MQ policy maintains a hit count for each cache block. For a
different block to get promoted to the cache it's hit count has to
exceed the lowest currently in the cache. This means it can take a
long time for the cache to adapt between varying IO patterns.
Periodically degrading the hit counts could help with this, but I
haven't found a nice general solution.SMQ doesn't maintain hit counts, so a lot of this problem just goes
away. In addition it tracks performance of the hotspot queue, which
is used to decide which blocks to promote. If the hotspot queue is
performing badly then it starts moving entries more quickly between
levels. This lets it adapt to new IO patterns very quickly.Performance
-----------In my tests SMQ shows substantially better performance than MQ. Once
this matures a bit more I'm sure it'll become the default policy.Signed-off-by: Joe Thornber
Signed-off-by: Mike Snitzer
25 Apr, 2015
1 commit
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Pull md updates from Neil Brown:
"More updates that usual this time. A few have performance impacts
which hould mostly be positive, but RAID5 (in particular) can be very
work-load ensitive... We'll have to wait and see.Highlights:
- "experimental" code for managing md/raid1 across a cluster using
DLM. Code is not ready for general use and triggers a WARNING if
used. However it is looking good and mostly done and having in
mainline will help co-ordinate development.- RAID5/6 can now batch multiple (4K wide) stripe_heads so as to
handle a full (chunk wide) stripe as a single unit.- RAID6 can now perform read-modify-write cycles which should help
performance on larger arrays: 6 or more devices.- RAID5/6 stripe cache now grows and shrinks dynamically. The value
set is used as a minimum.- Resync is now allowed to go a little faster than the 'mininum' when
there is competing IO. How much faster depends on the speed of the
devices, so the effective minimum should scale with device speed to
some extent"* tag 'md/4.1' of git://neil.brown.name/md: (58 commits)
md/raid5: don't do chunk aligned read on degraded array.
md/raid5: allow the stripe_cache to grow and shrink.
md/raid5: change ->inactive_blocked to a bit-flag.
md/raid5: move max_nr_stripes management into grow_one_stripe and drop_one_stripe
md/raid5: pass gfp_t arg to grow_one_stripe()
md/raid5: introduce configuration option rmw_level
md/raid5: activate raid6 rmw feature
md/raid6 algorithms: xor_syndrome() for SSE2
md/raid6 algorithms: xor_syndrome() for generic int
md/raid6 algorithms: improve test program
md/raid6 algorithms: delta syndrome functions
raid5: handle expansion/resync case with stripe batching
raid5: handle io error of batch list
RAID5: batch adjacent full stripe write
raid5: track overwrite disk count
raid5: add a new flag to track if a stripe can be batched
raid5: use flex_array for scribble data
md raid0: access mddev->queue (request queue member) conditionally because it is not set when accessed from dm-raid
md: allow resync to go faster when there is competing IO.
md: remove 'go_faster' option from ->sync_request()
...
16 Apr, 2015
1 commit
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Introduce a new target that is meant for file system developers to test file
system integrity at particular points in the life of a file system. We capture
all write requests and associated data and log them to a separate device
for later replay. There is a userspace utility to do this replay. The
idea behind this is to give file system developers a tool to verify that
the file system is always consistent.Signed-off-by: Josef Bacik
Reviewed-by: Zach Brown
Signed-off-by: Mike Snitzer
23 Feb, 2015
1 commit
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Tagged as EXPERIMENTAL for now.
Signed-off-by: Goldwyn Rodrigues
28 Mar, 2014
1 commit
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dm-era is a target that behaves similar to the linear target. In
addition it keeps track of which blocks were written within a user
defined period of time called an 'era'. Each era target instance
maintains the current era as a monotonically increasing 32-bit
counter.Use cases include tracking changed blocks for backup software, and
partially invalidating the contents of a cache to restore cache
coherency after rolling back a vendor snapshot.dm-era is primarily expected to be paired with the dm-cache target.
Signed-off-by: Joe Thornber
Signed-off-by: Mike Snitzer
15 Jan, 2014
1 commit
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This reverts commit be35f48610 ("dm: wait until embedded kobject is
released before destroying a device") and provides an improved fix.The kobject release code that calls the completion must be placed in a
non-module file, otherwise there is a module unload race (if the process
calling dm_kobject_release is preempted and the DM module unloaded after
the completion is triggered, but before dm_kobject_release returns).To fix this race, this patch moves the completion code to dm-builtin.c
which is always compiled directly into the kernel if BLK_DEV_DM is
selected.The patch introduces a new dm_kobject_holder structure, its purpose is
to keep the completion and kobject in one place, so that it can be
accessed from non-module code without the need to export the layout of
struct mapped_device to that code.Signed-off-by: Mikulas Patocka
Signed-off-by: Mike Snitzer
Cc: stable@vger.kernel.org
06 Sep, 2013
1 commit
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Support the collection of I/O statistics on user-defined regions of
a DM device. If no regions are defined no statistics are collected so
there isn't any performance impact. Only bio-based DM devices are
currently supported.Each user-defined region specifies a starting sector, length and step.
Individual statistics will be collected for each step-sized area within
the range specified.The I/O statistics counters for each step-sized area of a region are
in the same format as /sys/block/*/stat or /proc/diskstats but extra
counters (12 and 13) are provided: total time spent reading and
writing in milliseconds. All these counters may be accessed by sending
the @stats_print message to the appropriate DM device via dmsetup.The creation of DM statistics will allocate memory via kmalloc or
fallback to using vmalloc space. At most, 1/4 of the overall system
memory may be allocated by DM statistics. The admin can see how much
memory is used by reading
/sys/module/dm_mod/parameters/stats_current_allocated_bytesSee Documentation/device-mapper/statistics.txt for more details.
Signed-off-by: Mikulas Patocka
Signed-off-by: Mike Snitzer
Signed-off-by: Alasdair G Kergon
11 Jul, 2013
1 commit
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dm-switch is a new target that maps IO to underlying block devices
efficiently when there is a large number of fixed-sized address regions
but there is no simple pattern to allow for a compact mapping
representation such as dm-stripe.Though we have developed this target for a specific storage device, Dell
EqualLogic, we have made an effort to keep it as general purpose as
possible in the hope that others may benefit.Originally developed by Jim Ramsay. Simplified by Mikulas Patocka.
Signed-off-by: Jim Ramsay
Signed-off-by: Mikulas Patocka
Signed-off-by: Alasdair G Kergon
24 Mar, 2013
1 commit
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Does writethrough and writeback caching, handles unclean shutdown, and
has a bunch of other nifty features motivated by real world usage.See the wiki at http://bcache.evilpiepirate.org for more.
Signed-off-by: Kent Overstreet
02 Mar, 2013
3 commits
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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
Signed-off-by: Joe Thornber
Signed-off-by: Alasdair G Kergon -
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 -
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
13 Oct, 2012
1 commit
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The bio prison code will be useful to other future DM targets so
move it to a separate module.Signed-off-by: Mike Snitzer
Signed-off-by: Joe Thornber
Signed-off-by: Alasdair G Kergon
29 Mar, 2012
1 commit
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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
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
01 Nov, 2011
2 commits
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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.txtSigned-off-by: Joe Thornber
Signed-off-by: Mike Snitzer
Signed-off-by: Alasdair G Kergon -
The dm-bufio interface allows you to do cached I/O on devices,
holding recently-read blocks in memory and performing delayed writes.We don't use buffer cache or page cache already present in the kernel, because:
* we need to handle block sizes larger than a page
* we can't allocate memory to perform reads or we'd have deadlocksCurrently, when a cache is required, we limit its size to a fraction of
available memory. Usage can be viewed and changed in
/sys/module/dm_bufio/parameters/ .The first user is thin provisioning, but more dm users are planned.
Signed-off-by: Mikulas Patocka
Signed-off-by: Alasdair G Kergon
24 Mar, 2011
1 commit
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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
Signed-off-by: Alasdair G Kergon
14 Jan, 2011
1 commit
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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: raid \
2: \
3: ..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 in sectors.
[[no]sync] Force/Prevent RAID initialization
[rebuild ] Rebuild the drive indicated by the index
[daemon_sleep ] Time between bitmap daemon work to clear bits
[min_recovery_rate ] Throttle RAID initialization
[max_recovery_rate ] Throttle RAID initialization
[max_write_behind ] See '-write-behind=' (man mdadm)
[stripe_cache ] Stripe cache size for higher RAIDsLine 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 - 8:81Performing 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: raid \
2: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
Signed-off-by: Jonathan Brassow
Signed-off-by: Mike Snitzer
Signed-off-by: Alasdair G Kergon
09 Aug, 2010
1 commit
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Conflicts:
drivers/md/Makefile
lib/raid6/unroll.pl
29 Oct, 2009
1 commit
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We'll want to use these in btrfs too.
Signed-off-by: David Woodhouse
16 Oct, 2009
1 commit
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drivers/md/unroll.pl replaced by awk script to drop build-time
dependency on perlSigned-off-by: Vladimir Dronnikov
Signed-off-by: NeilBrown
22 Jun, 2009
3 commits
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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
Cc: Evgeniy Polyakov
Signed-off-by: Alasdair G Kergon -
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
Signed-off-by: Jun'ichi Nomura
Signed-off-by: Alasdair G Kergon -
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.htmlSigned-off-by: Stefan Bader
Signed-off-by: Kiyoshi Ueda
Signed-off-by: Jun'ichi Nomura
Signed-off-by: Alasdair G Kergon
31 Mar, 2009
2 commits
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Move the raid6 data processing routines into a standalone module
(raid6_pq) to prepare them to be called from async_tx wrappers and other
non-md drivers/modules. This precludes a circular dependency of raid456
needing the async modules for data processing while those modules in
turn depend on raid456 for the base level synchronous raid6 routines.To support this move:
1/ The exportable definitions in raid6.h move to include/linux/raid/pq.h
2/ The raid6_call, recovery calls, and table symbols are exported
3/ Extra #ifdef __KERNEL__ statements to enable the userspace raid6test to
compileSigned-off-by: Dan Williams
Signed-off-by: NeilBrown -
Use the -y variables instead of the old -objs so we can easily add
conditional objects to the modules. Also always use += to add
subobjects to avoid problems when placing additional objects in
some place in the file.Signed-off-by: Christoph Hellwig
Signed-off-by: NeilBrown
06 Jan, 2009
2 commits
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Move the existing snapshot exception store implementations out into
separate files. Later patches will place these behind a new
interface in preparation for alternative implementations.Signed-off-by: Alasdair G Kergon
-
Implement simple read-only sysfs entry for device-mapper block device.
This patch adds a simple sysfs directory named "dm" under block device
properties and implements
- name attribute (string containing mapped device name)
- uuid attribute (string containing UUID, or empty string if not set)The kobject is embedded in mapped_device struct, so no additional
memory allocation is needed for initializing sysfs entry.During the processing of sysfs attribute we need to lock mapped device
which is done by a new function dm_get_from_kobj, which returns the md
associated with kobject and increases the usage count.Each 'show attribute' function is responsible for its own locking.
Signed-off-by: Milan Broz
Signed-off-by: Alasdair G Kergon
22 Oct, 2008
1 commit
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Separate the region hash code from raid1 so it can be shared by forthcoming
targets. Use BUG_ON() for failed async dm_io() calls.Signed-off-by: Heinz Mauelshagen
Signed-off-by: Alasdair G Kergon
05 Jun, 2008
2 commits
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This patch just removes infrastructure that provided support for hardware
handlers in the dm layer as it is not needed anymore.Signed-off-by: Chandra Seetharaman
Acked-by: Alasdair G Kergon
Signed-off-by: James Bottomley -
This patch removes the 3 hardware handlers that currently exist
under dm as the functionality is moved to SCSI layer in the earlier
patches.[jejb: removed more makefile hunks and rejection fixes]
Signed-off-by: Chandra Seetharaman
Acked-by: Alasdair G Kergon
Signed-off-by: James Bottomley
25 Apr, 2008
2 commits
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Publish the dm-io, dm-log and dm-kcopyd headers in include/linux.
Signed-off-by: Alasdair G Kergon
-
Move the dirty region log code into a separate module so
other targets can share the code.Signed-off-by: Heinz Mauelshagen
Signed-off-by: Alasdair G Kergon
20 Oct, 2007
2 commits
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This patch adds a uevent skeleton to device-mapper.
Signed-off-by: Mike Anderson
Signed-off-by: Alasdair G Kergon -
This patch adds the most basic dm-multipath hardware support for the
HP active/passive arrays.Signed-off-by: Dave Wysochanski
Signed-off-by: Mike Christie
Acked-by: Chandra Seetharaman
Signed-off-by: Alasdair G Kergon
