Pull documentation updates from Jonathan Corbet:
"This is a fairly typical cycle for documentation. There's some welcome
readability improvements for the formatted output, some LICENSES
updates including the addition of the ISC license, the removal of the
unloved and unmaintained 00-INDEX files, the deprecated APIs document
from Kees, more MM docs from Mike Rapoport, and the usual pile of typo
fixes and corrections"
* tag 'docs-4.20' of git://git.lwn.net/linux: (41 commits)
docs: Fix typos in histogram.rst
docs: Introduce deprecated APIs list
kernel-doc: fix declaration type determination
doc: fix a typo in adding-syscalls.rst
docs/admin-guide: memory-hotplug: remove table of contents
doc: printk-formats: Remove bogus kobject references for device nodes
Documentation: preempt-locking: Use better example
dm flakey: Document "error_writes" feature
docs/completion.txt: Fix a couple of punctuation nits
LICENSES: Add ISC license text
LICENSES: Add note to CDDL-1.0 license that it should not be used
docs/core-api: memory-hotplug: add some details about locking internals
docs/core-api: rename memory-hotplug-notifier to memory-hotplug
docs: improve readability for people with poorer eyesight
yama: clarify ptrace_scope=2 in Yama documentation
docs/vm: split memory hotplug notifier description to Documentation/core-api
docs: move memory hotplug description into admin-guide/mm
doc: Fix acronym "FEKEK" in ecryptfs
docs: fix some broken documentation references
iommu: Fix passthrough option documentation
...
Commit ef548c551e ("dm flakey: introduce "error_writes" feature")
added the ability to dm flakey to error out writes in contrast to
silently dropping it with 'drop_writes'. Unfortunately this feature
is not currently documented and one has to be either familiar with the
source code of dm flakey or check out xfstests sources to know of
this parameter. So document it.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Bump target version to reflect the documented fixes are available.
Also fix some code comments (typos and clarity).
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <agrover@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <dhastings@crucialwebhost.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <mpatocka@redhat.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com> # fix missing goto
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> # fix compilation issue with !DAX
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> # use msecs_to_jiffies
Acked-by: Dan Williams <dan.j.williams@intel.com> # reworks to unify ARM and x86 flushing
Signed-off-by: Mike Snitzer <msnitzer@redhat.com>
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 <snitzer@redhat.com>
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 <totte@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
In commit f8350daf7a ("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 <jpittman@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Make the format string for thinpool status more correct.
Swap the order of two items to correspond with reality.
Signed-off-by: mulhern <amulhern@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <amulhern@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
The 'mq' policy is no longer the default policy, and the default policy,
'smq', does not store hit counts.
Signed-off-by: mulhern <amulhern@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Use possessive pronoun where appropriate, instead of contraction.
Signed-off-by: mulhern <amulhern@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <scott.bauer@intel.com>
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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 = <max dev size> (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 <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Linus Torvalds
Nikolay Borisov
Bart Van Assche
Heinz Mauelshagen
Andy Grover
Mikulas Patocka
Mike Snitzer
Patrik Torstensson
John Pittman
mulhern
Scott Bauer
Jonathan Brassow