linux/Documentation
Andy Grover 63c8ecb626 dm thin: include metadata_low_watermark threshold in pool status
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>
2018-07-30 11:49:08 -04:00
..
ABI ABI: sysfs-devices-system-cpu: remove a broken reference 2018-06-15 18:10:01 -03:00
accelerators ocxl: Document new OCXL IOCTLs 2018-06-03 20:40:33 +10:00
accounting
acpi ACPI / Documentation: update ACPI customize method feature docs 2018-06-06 08:48:00 +02:00
admin-guide docs: kernel-parameters.txt: document xhci-hcd.quirks parameter 2018-07-06 16:28:30 +02:00
aoe
arm ARM: Device-tree updates 2018-06-11 17:57:38 -07:00
arm64 ARM: 2018-04-09 11:42:31 -07:00
auxdisplay Doc: misc-devices: move lcd-panel-cgram.txt to auxdisplay/ 2018-04-12 16:08:02 +02:00
backlight
block block: remov blk_queue_invalidate_tags 2018-06-15 08:13:35 -06:00
blockdev zram: introduce zram memory tracking 2018-06-07 17:34:34 -07:00
bpf bpf, doc: howto use/run the BPF selftests 2018-05-14 23:02:58 -07:00
bus-devices
cdrom Documentation/cdrom: fix German sharp s in LaTex 2018-03-08 19:35:29 -07:00
cgroup-v1 page cache: use xa_lock 2018-04-11 10:28:39 -07:00
cma
connector
console
core-api Fix Documentation build due to rename of main.c to mtrr.c 2018-06-18 13:41:45 +09:00
cpu-freq cpufreq: Drop cpufreq_table_validate_and_show() 2018-04-10 08:40:45 +02:00
cpuidle cpuidle: Add definition of residency to sysfs documentation 2018-04-09 13:44:37 +02:00
crypto docs: crypto_engine.rst: Fix two parse warnings 2018-06-15 12:48:59 -03:00
dev-tools doc: dev-tools: kselftest.rst: update contributing new tests 2018-04-27 16:56:15 -06:00
device-mapper dm thin: include metadata_low_watermark threshold in pool status 2018-07-30 11:49:08 -04:00
devicetree DeviceTree fixes for 4.18: 2018-07-18 16:19:36 -07:00
doc-guide MAINTAINERS & files: Canonize the e-mails I use at files 2018-05-04 06:21:06 -04:00
driver-api Move all the dma-mapping code to kernel/dma 2018-06-20 16:30:01 +09:00
driver-model serdev: Introduce devm_serdev_device_open() 2018-01-08 10:08:34 +00:00
early-userspace
EDID
extcon
fault-injection Documentation: nvme: Documentation for nvme fault injection 2018-03-26 08:53:43 -06:00
fb
features Kbuild: rename HAVE_CC_STACKPROTECTOR config variable 2018-06-15 07:15:28 +09:00
filesystems Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
firmware_class
fmc
gpio Documentation: gpio: Move drivers-on-gpio.txt to driver-api 2018-03-23 04:22:29 +01:00
gpu Merge remote-tracking branch 'drm/drm-next' into drm-misc-next 2018-05-11 18:08:10 +02:00
hid
hwmon docs: Fix more broken references 2018-06-15 18:11:26 -03:00
i2c Merge branch 'i2c/for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2018-06-14 16:21:46 +09:00
ia64 ia64: doc: tweak whitespace for 'console=' parameter 2018-03-05 14:41:38 -08:00
ide
iio
infiniband Documentation/ABI: update infiniband sysfs interfaces 2018-02-23 08:18:33 -07:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2018-04-05 13:21:57 -07:00
ioctl SCSI misc on 20180610 2018-06-10 13:01:12 -07:00
isdn Documentation/isdn: check and fix dead links ... 2018-03-26 12:31:13 -04:00
kbuild kbuild: document the KBUILD_KCONFIG env. variable 2018-07-06 22:04:01 +09:00
kdump
kernel-hacking Documentation: Fix misconversion of #if 2018-01-17 16:45:01 -07:00
laptops platform/x86: thinkpad_acpi: silence HKEY 0x6032, 0x60f0, 0x6030 2018-05-07 15:10:31 +03:00
leds
lightnvm
livepatch livepatch: Remove not longer valid limitations from the documentation 2018-05-24 15:37:57 +02:00
locking Linux 4.16-rc2 2018-02-21 09:57:55 +01:00
m68k
maintainer docs: Fix more broken references 2018-06-15 18:11:26 -03:00
md raid5-ppl: PPL support for disks with write-back cache enabled 2018-01-15 14:29:42 -08:00
media media: cec: improve cec status documentation 2018-05-25 15:34:50 -04:00
memory-devices
mic
mips Documentation: mips: Update AU1xxx_IDE Kconfig dependencies 2018-02-01 12:45:35 -07:00
misc-devices Mostly small fixes and cleanups, plus a non-trivial fix for charlcd 2018-06-07 14:01:16 -07:00
mmc
mtd mtd: spi-nor: add an API to restore the status of SPI flash chip 2017-12-13 00:36:00 +01:00
namespaces
netlabel
networking bonding: Fix a typo in bonding.txt 2018-07-16 13:32:12 -07:00
nfc
nios2
nvdimm
nvmem
openrisc
parisc
PCI PCI/AER: Handle ERR_FATAL with removal and re-enumeration of devices 2018-05-17 16:44:13 -05:00
pcmcia
perf drivers/bus: Move Arm CCN PMU driver 2018-03-06 17:26:15 +01:00
phy
platform
power firmware: Fix firmware documentation for recent file renames 2018-04-23 13:03:26 +02:00
powerpc
pps
process There's been a fair amount of work in the docs tree this time around, 2018-06-04 12:34:27 -07:00
pti
ptp ptp: Fix documentation to match code. 2018-03-26 12:13:21 -04:00
rapidio Documentation: rapidio: move sysfs interface to ABI 2018-02-23 08:25:45 -07:00
RCU doc: Ensure whatisRCU.txt actually says what RCU is 2018-05-15 10:28:12 -07:00
riscv perf: riscv: Add Document for Future Porting Guide 2018-06-04 14:02:11 -07:00
s390 vfio-ccw: update documentation 2018-03-01 17:32:14 +01:00
scheduler sched/deadline/Documentation: Add overrun signal and GRUB-PA documentation 2018-05-14 09:12:27 +02:00
scsi block: remove BLK_EH_HANDLED 2018-05-29 08:59:21 -06:00
security Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
serial
sh
sound sound updates for 4.18 2018-06-06 09:08:38 -07:00
sparc sparc64: Add support for ADI (Application Data Integrity) 2018-03-18 07:38:48 -07:00
sphinx Documentation: rstFlatTable.py: fix a broken reference 2018-06-15 18:10:01 -03:00
sphinx-static
spi
sysctl Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-06-06 18:39:49 -07:00
target
thermal thermal: Add cooling device's statistics in sysfs 2018-04-02 21:49:01 +08:00
timers sched/isolation: Eliminate NO_HZ_FULL_ALL 2018-02-15 15:40:37 -08:00
trace tracing: Fix some errors in histogram documentation 2018-06-21 15:12:44 -04:00
translations fix a series of Documentation/ broken file name references 2018-06-15 18:10:01 -03:00
usb doc: usb: Fix typo in gadget_configfs documentation 2018-06-18 12:41:00 +03:00
userspace-api audit/stable-4.18 PR 20180605 2018-06-06 16:34:00 -07:00
virtual KVM: fix KVM_CAP_HYPERV_TLBFLUSH paragraph number 2018-06-22 17:30:20 +02:00
vm docs/vm: move ksm and transhuge from "user" to "internals" section. 2018-05-29 06:45:55 -06:00
w1 Documentation updates for 4.16. New stuff includes refcount_t 2018-01-31 19:25:25 -08:00
watchdog watchdog: remove bfin_wdt driver 2018-03-26 15:57:04 +02:00
wimax
x86 Merge branch 'x86-cache-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-04 21:34:39 -07:00
xtensa xtensa: add support for KASAN 2017-12-16 22:37:12 -08:00
.gitignore
00-INDEX docs: admin-guide: add cgroup-v2 documentation 2018-05-10 15:42:41 -06:00
atomic_bitops.txt locking/atomic/bitops: Document and clarify ordering semantics for failed test_and_{}_bit() 2018-02-13 14:55:53 +01:00
atomic_t.txt
bt8xxgpio.txt
btmrvl.txt
bus-virt-phys-mapping.txt
Changes
clearing-warn-once.txt kernel debug: support resetting WARN*_ONCE 2017-11-17 16:10:00 -08:00
CodingStyle
conf.py docs: Remove "could not extract kernel version" warning 2017-12-11 15:20:04 -07:00
cpu-load.txt
cputopology.txt
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt Documentation: remove stale firmware API reference 2018-05-14 16:44:41 +02:00
digsig.txt
DMA-API-HOWTO.txt
DMA-API.txt
DMA-attributes.txt
DMA-ISA-LPC.txt
docutils.conf
dontdiff
efi-stub.txt
eisa.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcc-plugins.txt
highuid.txt
hw_random.txt
hwspinlock.txt
index.rst docs/vm: add index.rst and link MM documentation to top level index 2018-04-16 14:18:15 -06:00
intel_txt.txt
Intel-IOMMU.txt
io_ordering.txt
io-mapping.txt
iostats.txt
IPMI.txt
IRQ-affinity.txt
IRQ-domain.txt irqdomain: Kill CONFIG_IRQ_DOMAIN_DEBUG 2018-01-24 12:32:58 +01:00
IRQ.txt
irqflags-tracing.txt
isa.txt
isapnp.txt
kernel-per-CPU-kthreads.txt
kobject.txt
kprobes.txt docs: Fix some broken references 2018-06-15 18:10:01 -03:00
kref.txt
ldm.txt
lockup-watchdogs.txt
logo.gif
logo.txt
lsm.txt
lzo.txt
mailbox.txt
Makefile
memory-barriers.txt Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-04 16:40:11 -07:00
memory-hotplug.txt
men-chameleon-bus.txt
nommu-mmap.txt
ntb.txt
numastat.txt
padata.txt
parport-lowlevel.txt
percpu-rw-semaphore.txt
phy.txt
pi-futex.txt
pnp.txt
preempt-locking.txt
pwm.txt
rbtree.txt
remoteproc.txt
rfkill.txt
robust-futex-ABI.txt
robust-futexes.txt
rpmsg.txt
rtc.txt Documentation: rtc: move iotcl interface documentation to ABI 2018-01-12 00:20:41 +01:00
SAK.txt
sgi-ioc4.txt
siphash.txt
SM501.txt
smsc_ece1099.txt
speculation.txt Documentation: Document array_index_nospec 2018-01-30 21:54:28 +01:00
static-keys.txt
SubmittingPatches
svga.txt documentation/svga.txt: update outdated file 2017-11-20 10:45:50 -07:00
switchtec.txt NTB: switchtec_ntb: Update switchtec documentation with notes for NTB 2017-11-18 20:37:13 -05:00
sync_file.txt
tee.txt
this_cpu_ops.txt
unaligned-memory-access.txt
vfio-mediated-device.txt vfio/mdev: Check globally for duplicate devices 2018-06-08 10:24:27 -06:00
vfio.txt vfio: fix documentation 2018-05-08 09:16:41 -06:00
video-output.txt
xillybus.txt
xz.txt
zorro.txt