07 Sep, 2018
1 commit
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Bump target version to reflect the documented fixes are available.
Also fix some code comments (typos and clarity).Signed-off-by: Heinz Mauelshagen
Signed-off-by: Mike Snitzer
30 Jul, 2018
1 commit
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The metadata low watermark threshold is set by the kernel. But the
kernel depends on userspace to extend the thinpool metadata device when
the threshold is crossed.Since the metadata low watermark threshold is not visible to userspace,
upon receiving an event, userspace cannot tell that the kernel wants the
metadata device extended, instead of some other eventing condition.
Making it visible (but not settable) enables userspace to affirmatively
know the kernel is asking for a metadata device extension, by comparing
metadata_low_watermark against nr_free_blocks_metadata, also reported in
status.Current solutions like dmeventd have their own thresholds for extending
the data and metadata devices, and both devices are checked against
their thresholds on each event. This lessens the value of the kernel-set
threshold, since userspace will either extend the metadata device sooner,
when receiving another event; or will receive the metadata lowater event
and do nothing, if dmeventd's threshold is less than the kernel's.
(This second case is dangerous. The metadata lowater event will not be
re-sent, so no further event will be generated before the metadata
device is out if space, unless some other event causes userspace to
recheck its thresholds.)Signed-off-by: Andy Grover
Signed-off-by: Mike Snitzer
28 Jul, 2018
3 commits
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When using external metadata device and internal hash, recalculate the
checksums when the device is created - so that dm-integrity doesn't
have to overwrite the device. The superblock stores the last position
when the recalculation ended, so that it is properly restarted.Integrity tags that haven't been recalculated yet are ignored.
Also bump the target version.
Signed-off-by: Mikulas Patocka
Signed-off-by: Mike Snitzer -
Add a new class for dm-delay that delays flush requests. Previously,
flushes were delayed as writes, but it caused problems if the user
needed to create a device with one or a few slow sectors for the purpose
of testing - all flushes would be forwarded to this device and delayed,
and that skews the test results. Fix this by allowing to select 0 delay
for flushes.Signed-off-by: Mikulas Patocka
Signed-off-by: Mike Snitzer -
Documentation/device-mapper-/thin-provisioning.txt's "Status" section no
longer reflected the current fitness level of DM thin-provisioning.
That is, DM thinp is no longer "EXPERIMENTAL". It has since seen
considerable improvement, has been fairly widely deployed and has
performed in a robust manner.Update Documentation to dispel concern raised by potential DM thinp
users.Reported-by: Drew Hastings
Signed-off-by: Mike Snitzer
03 Jul, 2018
1 commit
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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
08 Jun, 2018
1 commit
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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
10 May, 2018
1 commit
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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
04 Apr, 2018
1 commit
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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
31 Jan, 2018
1 commit
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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
17 Jan, 2018
9 commits
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Signed-off-by: mulhern
Signed-off-by: Mike Snitzer -
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 -
Signed-off-by: mulhern
Signed-off-by: Mike Snitzer -
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 -
Signed-off-by: mulhern
Signed-off-by: Mike Snitzer -
The 'mq' policy is no longer the default policy, and the default policy,
'smq', does not store hit counts.Signed-off-by: mulhern
Signed-off-by: Mike Snitzer -
Use possessive pronoun where appropriate, instead of contraction.
Signed-off-by: mulhern
Signed-off-by: Mike Snitzer -
Add a note to snapshot.txt that the origin target must be suspended when
loading or unloading the snapshot target.Signed-off-by: Mikulas Patocka
Signed-off-by: Mike Snitzer -
This device mapper "unstriped" target remaps and unstripes I/O so it
is issued solely on a single drive in a HW RAID0 or dm-striped target.In a 4 drive HW RAID0 the striped target exposes 1/4th of the LBA range
as a virtual drive. Each I/O to that virtual drive will only be issued
to the 1 drive that was selected of the 4 drives in the HW RAID0.This unstriped target is most useful for Intel NVMe drives that have
multiple cores but that do not have firmware control to pin separate LBA
ranges to each discrete cpu core.Signed-off-by: Scott Bauer
Signed-off-by: Heinz Mauelshagen
Acked-by: Keith Busch
Signed-off-by: Mike Snitzer
14 Dec, 2017
1 commit
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In order to avoid redoing synchronization/recovery/reshape partially,
the raid set got frozen until after all passed in table line flags had
been cleared. The related table reload sequence had to be precisely
followed, or reshaping may lead to data corruption caused by the active
mapping carrying on with a reshape when the inactive mapping already
had retrieved a stale reshape position.Harden by retrieving the actual resync/recovery/reshape position
during resume whilst the active table is suspended thus avoiding
to keep the raid set frozen altogether. This prevents superfluous
redoing of an already resynchronized or recovered segment and,
most importantly, potential for redoing of an already reshaped
segment causing data corruption.Fixes: d39f0010e ("dm raid: fix raid_resume() to keep raid set frozen as needed")
Signed-off-by: Heinz Mauelshagen
Signed-off-by: Mike Snitzer
08 Dec, 2017
1 commit
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Also update Documentation accordingly.
Signed-off-by: Mike Snitzer
06 Oct, 2017
1 commit
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There are three important fields that indicate the overall health and
status of an array: dev_health, sync_ratio, and sync_action. They tell
us the condition of the devices in the array, and the degree to which
the array is synchronized.This commit fixes a condition that is reported incorrectly. When a member
of the array is being rebuilt or a new device is added, the "recover"
process is used to synchronize it with the rest of the array. When the
process is complete, but the sync thread hasn't yet been reaped, it is
possible for the state of MD to be:
mddev->recovery = [ MD_RECOVERY_RUNNING MD_RECOVERY_RECOVER MD_RECOVERY_DONE ]
curr_resync_completed = (but not MaxSector)
and all rdevs to be In_sync.
This causes the 'array_in_sync' output parameter that is passed to
rs_get_progress() to be computed incorrectly and reported as 'false' --
or not in-sync. This in turn causes the dev_health status characters to
be reported as all 'a', rather than the proper 'A'.This can cause erroneous output for several seconds at a time when tools
will want to be checking the condition due to events that are raised at
the end of a sync process. Fix this by properly calculating the
'array_in_sync' return parameter in rs_get_progress().Also, remove an unnecessary intermediate 'recovery_cp' variable in
rs_get_progress().Signed-off-by: Jonathan Brassow
Signed-off-by: Mike Snitzer
26 Jul, 2017
1 commit
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Bumo dm-raid target version to 1.12.1 to reflect that commit cc27b0c78c
("md: fix deadlock between mddev_suspend() and md_write_start()") is
available.This version change allows userspace to detect that MD fix is available.
Signed-off-by: Heinz Mauelshagen
Signed-off-by: Mike Snitzer
19 Jun, 2017
1 commit
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The dm-zoned device mapper target provides transparent write access
to zoned block devices (ZBC and ZAC compliant block devices).
dm-zoned hides to the device user (a file system or an application
doing raw block device accesses) any constraint imposed on write
requests by the device, equivalent to a drive-managed zoned block
device model.Write requests are processed using a combination of on-disk buffering
using the device conventional zones and direct in-place processing for
requests aligned to a zone sequential write pointer position.
A background reclaim process implemented using dm_kcopyd_copy ensures
that conventional zones are always available for executing unaligned
write requests. The reclaim process overhead is minimized by managing
buffer zones in a least-recently-written order and first targeting the
oldest buffer zones. Doing so, blocks under regular write access (such
as metadata blocks of a file system) remain stored in conventional
zones, resulting in no apparent overhead.dm-zoned implementation focus on simplicity and on minimizing overhead
(CPU, memory and storage overhead). For a 14TB host-managed disk with
256 MB zones, dm-zoned memory usage per disk instance is at most about
3 MB and as little as 5 zones will be used internally for storing metadata
and performing buffer zone reclaim operations. This is achieved using
zone level indirection rather than a full block indirection system for
managing block movement between zones.dm-zoned primary target is host-managed zoned block devices but it can
also be used with host-aware device models to mitigate potential
device-side performance degradation due to excessive random writing.Zoned block devices can be formatted and checked for use with the dm-zoned
target using the dmzadm utility available at:https://github.com/hgst/dm-zoned-tools
Signed-off-by: Damien Le Moal
Reviewed-by: Hannes Reinecke
Reviewed-by: Bart Van Assche
[Mike Snitzer partly refactored Damien's original work to cleanup the code]
Signed-off-by: Mike Snitzer
04 May, 2017
1 commit
-
…/device-mapper/linux-dm
Pull device mapper updates from Mike Snitzer:
- A major update for DM cache that reduces the latency for deciding
whether blocks should migrate to/from the cache. The bio-prison-v2
interface supports this improvement by enabling direct dispatch of
work to workqueues rather than having to delay the actual work
dispatch to the DM cache core. So the dm-cache policies are much more
nimble by being able to drive IO as they see fit. One immediate
benefit from the improved latency is a cache that should be much more
adaptive to changing workloads.- Add a new DM integrity target that emulates a block device that has
additional per-sector tags that can be used for storing integrity
information.- Add a new authenticated encryption feature to the DM crypt target
that builds on the capabilities provided by the DM integrity target.- Add MD interface for switching the raid4/5/6 journal mode and update
the DM raid target to use it to enable aid4/5/6 journal write-back
support.- Switch the DM verity target over to using the asynchronous hash
crypto API (this helps work better with architectures that have
access to off-CPU algorithm providers, which should reduce CPU
utilization).- Various request-based DM and DM multipath fixes and improvements from
Bart and Christoph.- A DM thinp target fix for a bio structure leak that occurs for each
discard IFF discard passdown is enabled.- A fix for a possible deadlock in DM bufio and a fix to re-check the
new buffer allocation watermark in the face of competing admin
changes to the 'max_cache_size_bytes' tunable.- A couple DM core cleanups.
* tag 'for-4.12/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (50 commits)
dm bufio: check new buffer allocation watermark every 30 seconds
dm bufio: avoid a possible ABBA deadlock
dm mpath: make it easier to detect unintended I/O request flushes
dm mpath: cleanup QUEUE_IF_NO_PATH bit manipulation by introducing assign_bit()
dm mpath: micro-optimize the hot path relative to MPATHF_QUEUE_IF_NO_PATH
dm: introduce enum dm_queue_mode to cleanup related code
dm mpath: verify __pg_init_all_paths locking assumptions at runtime
dm: verify suspend_locking assumptions at runtime
dm block manager: remove an unused argument from dm_block_manager_create()
dm rq: check blk_mq_register_dev() return value in dm_mq_init_request_queue()
dm mpath: delay requeuing while path initialization is in progress
dm mpath: avoid that path removal can trigger an infinite loop
dm mpath: split and rename activate_path() to prepare for its expanded use
dm ioctl: prevent stack leak in dm ioctl call
dm integrity: use previously calculated log2 of sectors_per_block
dm integrity: use hex2bin instead of open-coded variant
dm crypt: replace custom implementation of hex2bin()
dm crypt: remove obsolete references to per-CPU state
dm verity: switch to using asynchronous hash crypto API
dm crypt: use WQ_HIGHPRI for the IO and crypt workqueues
...
25 Apr, 2017
2 commits
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The DM integrity block size can now be 512, 1k, 2k or 4k. Using larger
blocks reduces metadata handling overhead. The block size can be
configured at table load time using the "block_size:" option;
where is expressed in bytes (defult is still 512 bytes).It is safe to use larger block sizes with DM integrity, because the
DM integrity journal makes sure that the whole block is updated
atomically even if the underlying device doesn't support atomic writes
of that size (e.g. 4k block ontop of a 512b device).Depends-on: 2859323e ("block: fix blk_integrity_register to use template's interval_exp if not 0")
Signed-off-by: Mikulas Patocka
Signed-off-by: Mike Snitzer -
Some coding style changes.
Fix a bug that the array test_tag has insufficient size if the digest
size of internal has is bigger than the tag size.The function __fls is undefined for zero argument, this patch fixes
undefined behavior if the user sets zero interleave_sectors.Fix the limit of optional arguments to 8.
Don't allocate crypt_data on the stack to avoid a BUG with debug kernel.
Rename all optional argument names to have underscores rather than
dashes.Signed-off-by: Mikulas Patocka
Signed-off-by: Mike Snitzer
28 Mar, 2017
1 commit
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Commit 63c32ed4afc ("dm raid: add raid4/5/6 journaling support") added
journal support to close the raid4/5/6 "write hole" -- in terms of
writethrough caching.Introduce a "journal_mode" feature and use the new
r5c_journal_mode_set() API to add support for switching the journal
device's cache mode between write-through (the current default) and
write-back.NOTE: If the journal device is not layered on resilent storage and it
fails, write-through mode will cause the "write hole" to reoccur. But
if the journal fails while in write-back mode it will cause data loss
for any dirty cache entries unless resilent storage is used for the
journal.Signed-off-by: Heinz Mauelshagen
Signed-off-by: Mike Snitzer
27 Mar, 2017
1 commit
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Commit 3a1c1ef2f ("dm raid: enhance status interface and fixup
takeover/raid0") added new table line arguments and introduced an
ordering flaw. The sequence of the raid10_copies and raid10_format
raid parameters got reversed which causes lvm2 userspace to fail by
falsely assuming a changed table line.Sequence those 2 parameters as before so that old lvm2 can function
properly with new kernels by adjusting the table line output as
documented in Documentation/device-mapper/dm-raid.txt.Also, add missing version 1.10.1 highlight to the documention.
Fixes: 3a1c1ef2f ("dm raid: enhance status interface and fixup takeover/raid0")
Signed-off-by: Heinz Mauelshagen
Signed-off-by: Mike Snitzer
25 Mar, 2017
5 commits
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In recovery mode, we don't:
- replay the journal
- check checksums
- allow writes to the deviceThis mode can be used as a last resort for data recovery. The
motivation for recovery mode is that when there is a single error in the
journal, the user should not lose access to the whole device.Signed-off-by: Mikulas Patocka
Signed-off-by: Mike Snitzer -
Add optional "sector_size" parameter that specifies encryption sector
size (atomic unit of block device encryption).Parameter can be in range 512 - 4096 bytes and must be power of two.
For compatibility reasons, the maximal IO must fit into the page limit,
so the limit is set to the minimal page size possible (4096 bytes).NOTE: this device cannot yet be handled by cryptsetup if this parameter
is set.IV for the sector is calculated from the 512 bytes sector offset unless
the iv_large_sectors option is used.Test script using dmsetup:
DEV="/dev/sdb"
DEV_SIZE=$(blockdev --getsz $DEV)
KEY="9c1185a5c5e9fc54612808977ee8f548b2258d31ddadef707ba62c166051b9e3cd0294c27515f2bccee924e8823ca6e124b8fc3167ed478bca702babe4e130ac"
BLOCK_SIZE=4096# dmsetup create test_crypt --table "0 $DEV_SIZE crypt aes-xts-plain64 $KEY 0 $DEV 0 1 sector_size:$BLOCK_SIZE"
# dmsetup table --showkeys test_cryptSigned-off-by: Milan Broz
Signed-off-by: Mike Snitzer -
For the new authenticated encryption we have to support generic composed
modes (combination of encryption algorithm and authenticator) because
this is how the kernel crypto API accesses such algorithms.To simplify the interface, we accept an algorithm directly in crypto API
format. The new format is recognised by the "capi:" prefix. The
dmcrypt internal IV specification is the same as for the old format.The crypto API cipher specifications format is:
capi:cipher_api_spec-ivmode[:ivopts]
Examples:
capi:cbc(aes)-essiv:sha256 (equivalent to old aes-cbc-essiv:sha256)
capi:xts(aes)-plain64 (equivalent to old aes-xts-plain64)
Examples of authenticated modes:
capi:gcm(aes)-random
capi:authenc(hmac(sha256),xts(aes))-random
capi:rfc7539(chacha20,poly1305)-randomAuthenticated modes can only be configured using the new cipher format.
Note that this format allows user to specify arbitrary combinations that
can be insecure. (Policy decision is done in cryptsetup userspace.)Authenticated encryption algorithms can be of two types, either native
modes (like GCM) that performs both encryption and authentication
internally, or composed modes where user can compose AEAD with separate
specification of encryption algorithm and authenticator.For composed mode with HMAC (length-preserving encryption mode like an
XTS and HMAC as an authenticator) we have to calculate HMAC digest size
(the separate authentication key is the same size as the HMAC digest).
Introduce crypt_ctr_auth_cipher() to parse the crypto API string to get
HMAC algorithm and retrieve digest size from it.Also, for HMAC composed mode we need to parse the crypto API string to
get the cipher mode nested in the specification. For native AEAD mode
(like GCM), we can use crypto_tfm_alg_name() API to get the cipher
specification.Because the HMAC composed mode is not processed the same as the native
AEAD mode, the CRYPT_MODE_INTEGRITY_HMAC flag is no longer needed and
"hmac" specification for the table integrity argument is removed.Signed-off-by: Milan Broz
Signed-off-by: Mike Snitzer -
Allow the use of per-sector metadata, provided by the dm-integrity
module, for integrity protection and persistently stored per-sector
Initialization Vector (IV). The underlying device must support the
"DM-DIF-EXT-TAG" dm-integrity profile.The per-bio integrity metadata is allocated by dm-crypt for every bio.
Example of low-level mapping table for various types of use:
DEV=/dev/sdb
SIZE=417792# Additional HMAC with CBC-ESSIV, key is concatenated encryption key + HMAC key
SIZE_INT=389952
dmsetup create x --table "0 $SIZE_INT integrity $DEV 0 32 J 0"
dmsetup create y --table "0 $SIZE_INT crypt aes-cbc-essiv:sha256 \
11ff33c6fb942655efb3e30cf4c0fd95f5ef483afca72166c530ae26151dd83b \
00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff \
0 /dev/mapper/x 0 1 integrity:32:hmac(sha256)"# AEAD (Authenticated Encryption with Additional Data) - GCM with random IVs
# GCM in kernel uses 96bits IV and we store 128bits auth tag (so 28 bytes metadata space)
SIZE_INT=393024
dmsetup create x --table "0 $SIZE_INT integrity $DEV 0 28 J 0"
dmsetup create y --table "0 $SIZE_INT crypt aes-gcm-random \
11ff33c6fb942655efb3e30cf4c0fd95f5ef483afca72166c530ae26151dd83b \
0 /dev/mapper/x 0 1 integrity:28:aead"# Random IV only for XTS mode (no integrity protection but provides atomic random sector change)
SIZE_INT=401272
dmsetup create x --table "0 $SIZE_INT integrity $DEV 0 16 J 0"
dmsetup create y --table "0 $SIZE_INT crypt aes-xts-random \
11ff33c6fb942655efb3e30cf4c0fd95f5ef483afca72166c530ae26151dd83b \
0 /dev/mapper/x 0 1 integrity:16:none"# Random IV with XTS + HMAC integrity protection
SIZE_INT=377656
dmsetup create x --table "0 $SIZE_INT integrity $DEV 0 48 J 0"
dmsetup create y --table "0 $SIZE_INT crypt aes-xts-random \
11ff33c6fb942655efb3e30cf4c0fd95f5ef483afca72166c530ae26151dd83b \
00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff \
0 /dev/mapper/x 0 1 integrity:48:hmac(sha256)"Both AEAD and HMAC protection authenticates not only data but also
sector metadata.HMAC protection is implemented through autenc wrapper (so it is
processed the same way as an authenticated mode).In HMAC mode there are two keys (concatenated in dm-crypt mapping
table). First is the encryption key and the second is the key for
authentication (HMAC). (It is userspace decision if these keys are
independent or somehow derived.)The sector request for AEAD/HMAC authenticated encryption looks like this:
|----- AAD -------|------ DATA -------|-- AUTH TAG --|
| (authenticated) | (auth+encryption) | |
| sector_LE | IV | sector in/out | tag in/out |For writes, the integrity fields are calculated during AEAD encryption
of every sector and stored in bio integrity fields and sent to
underlying dm-integrity target for storage.For reads, the integrity metadata is verified during AEAD decryption of
every sector (they are filled in by dm-integrity, but the integrity
fields are pre-allocated in dm-crypt).There is also an experimental support in cryptsetup utility for more
friendly configuration (part of LUKS2 format).Because the integrity fields are not valid on initial creation, the
device must be "formatted". This can be done by direct-io writes to the
device (e.g. dd in direct-io mode). For now, there is available trivial
tool to do this, see: https://github.com/mbroz/dm_int_toolsSigned-off-by: Milan Broz
Signed-off-by: Ondrej Mosnacek
Signed-off-by: Vashek Matyas
Signed-off-by: Mike Snitzer -
The dm-integrity target emulates a block device that has additional
per-sector tags that can be used for storing integrity information.A general problem with storing integrity tags with every sector is that
writing the sector and the integrity tag must be atomic - i.e. in case of
crash, either both sector and integrity tag or none of them is written.To guarantee write atomicity the dm-integrity target uses a journal. It
writes sector data and integrity tags into a journal, commits the journal
and then copies the data and integrity tags to their respective location.The dm-integrity target can be used with the dm-crypt target - in this
situation the dm-crypt target creates the integrity data and passes them
to the dm-integrity target via bio_integrity_payload attached to the bio.
In this mode, the dm-crypt and dm-integrity targets provide authenticated
disk encryption - if the attacker modifies the encrypted device, an I/O
error is returned instead of random data.The dm-integrity target can also be used as a standalone target, in this
mode it calculates and verifies the integrity tag internally. In this
mode, the dm-integrity target can be used to detect silent data
corruption on the disk or in the I/O path.Signed-off-by: Mikulas Patocka
Signed-off-by: Milan Broz
Signed-off-by: Mike Snitzer
19 Mar, 2017
1 commit
-
Fix a spelling error (hexidecimal->hexadecimal).
Signed-off-by: sayli karnik
Signed-off-by: Jonathan Corbet
28 Feb, 2017
1 commit
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Fix typos and add the following to the scripts/spelling.txt:
explictely||explicitly
Link: http://lkml.kernel.org/r/1481573103-11329-25-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Feb, 2017
1 commit
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If "metadata2" is provided as a table argument when creating/loading a
cache target a more compact metadata format, with separate dirty bits,
is used. "metadata2" improves speed of shutting down a cache target.Signed-off-by: Joe Thornber
Signed-off-by: Mike Snitzer
25 Jan, 2017
2 commits
-
Add md raid4/5/6 journaling support (upstream commit bac624f3f86a started
the implementation) which closes the write hole (i.e. non-atomic updates
to stripes) using a dedicated journal device.Background:
raid4/5/6 stripes hold N data payloads per stripe plus one parity raid4/5
or two raid6 P/Q syndrome payloads in an in-memory stripe cache.
Parity or P/Q syndromes used to recover any data payloads in case of a disk
failure are calculated from the N data payloads and need to be updated on the
different component devices of the raid device. Those are non-atomic,
persistent updates. Hence a crash can cause failure to update all stripe
payloads persistently and thus cause data loss during stripe recovery.
This problem gets addressed by writing whole stripe cache entries (together with
journal metadata) to a persistent journal entry on a dedicated journal device.
Only if that journal entry is written successfully, the stripe cache entry is
updated on the component devices of the raid device (i.e. writethrough type).
In case of a crash, the entry can be recovered from the journal and be written
again thus ensuring consistent stripe payload suitable to data recovery.Future dependencies:
once writeback caching being worked on to compensate for the throughput
implictions involved with writethrough overhead is supported with journaling
in upstream, an additional patch based on this one will support it in dm-raid.Journal resilience related remarks:
because stripes are recovered from the journal in case of a crash, the
journal device better be resilient. Resilience becomes mandatory with
future writeback support, because loosing the working set in the log
means data loss as oposed to writethrough, were the loss of the
journal device 'only' reintroduces the write hole.Fix comment on data offsets in parse_dev_params() and initialize
new_data_offset as well.Signed-off-by: Heinz Mauelshagen
Signed-off-by: Mike Snitzer -
This fix addresses the following 3 failure scenarios:
1) If a (transiently) inaccessible metadata device is being passed into the
constructor (e.g. a device tuple '254:4 254:5'), it is processed as if
'- -' was given. This erroneously results in a status table line containing
'- -', which mistakenly differs from what has been passed in. As a result,
userspace libdevmapper puts the device tuple seperate from the RAID device
thus not processing the dependencies properly.2) False health status char 'A' instead of 'D' is emitted on the status
status info line for the meta/data device tuple in this metadata device
failure case.3) If the metadata device is accessible when passed into the constructor
but the data device (partially) isn't, that leg may be set faulty by the
raid personality on access to the (partially) unavailable leg. Restore
tried in a second raid device resume on such failed leg (status char 'D')
fails after the (partial) leg returned.Fixes for aforementioned failure scenarios:
- don't release passed in devices in the constructor thus allowing the
status table line to e.g. contain '254:4 254:5' rather than '- -'- emit device status char 'D' rather than 'A' for the device tuple
with the failed metadata device on the status info line- when attempting to restore faulty devices in a second resume, allow the
device hot remove function to succeed by setting the device to not in-syncIn case userspace intentionally passes '- -' into the constructor to avoid that
device tuple (e.g. to split off a raid1 leg temporarily for later re-addition),
the status table line will correctly show '- -' and the status info line will
provide a '-' device health character for the non-defined device tuple.Signed-off-by: Heinz Mauelshagen
Signed-off-by: Mike Snitzer
15 Dec, 2016
1 commit
-
Pull trivial updates from Jiri Kosina.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial:
NTB: correct ntb_spad_count comment typo
misc: ibmasm: fix typo in error message
Remove references to dead make variable LINUX_INCLUDE
Remove last traces of ikconfig.h
treewide: Fix printk() message errors
Documentation/device-mapper: s/getsize/getsz/