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a1e1cb72d9
linux/drivers
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Mike Snitzer a1e1cb72d9 dm: fix redundant IO accounting for bios that need splitting 
The risk of redundant IO accounting was not taken into consideration
when commit 18a25da843 ("dm: ensure bio submission follows a
depth-first tree walk") introduced IO splitting in terms of recursion
via generic_make_request().

Fix this by subtracting the split bio's payload from the IO stats that
were already accounted for by start_io_acct() upon dm_make_request()
entry.  This repeat oscillation of the IO accounting, up then down,
isn't ideal but refactoring DM core's IO splitting to pre-split bios
_before_ they are accounted turned out to be an excessive amount of
change that will need a full development cycle to refine and verify.

Before this fix:

  /dev/mapper/stripe_dev is a 4-way stripe using a 32k chunksize, so
  bios are split on 32k boundaries.

  # fio --name=16M --filename=/dev/mapper/stripe_dev --rw=write --bs=64k --size=16M \
    	--iodepth=1 --ioengine=libaio --direct=1 --refill_buffers

  with debugging added:
  [103898.310264] device-mapper: core: start_io_acct: dm-2 WRITE bio->bi_iter.bi_sector=0 len=128
  [103898.318704] device-mapper: core: __split_and_process_bio: recursing for following split bio:
  [103898.329136] device-mapper: core: start_io_acct: dm-2 WRITE bio->bi_iter.bi_sector=64 len=64
  ...

  16M written yet 136M (278528 * 512b) accounted:
  # cat /sys/block/dm-2/stat | awk '{ print $7 }'
  278528

After this fix:

  16M written and 16M (32768 * 512b) accounted:
  # cat /sys/block/dm-2/stat | awk '{ print $7 }'
  32768

Fixes: 18a25da843 ("dm: ensure bio submission follows a depth-first tree walk")
Cc: stable@vger.kernel.org # 4.16+
Reported-by: Bryan Gurney <bgurney@redhat.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-01-21 11:29:27 -05:00
..
accessibility
acpi Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
amba
android
ata for-4.21/libata-20190102 2019-01-02 18:47:56 -08:00
atm
auxdisplay auxdisplay: charlcd: fix x/y command parsing 2018-12-21 21:27:21 +01:00
base Merge branch 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-01-05 13:25:58 -08:00
bcma
block block: sunvdc: don't run hw queue synchronously from irq context 2019-01-03 08:21:47 -07:00
bluetooth Bluetooth: hci_bcm: Handle specific unknown packets after firmware loading 2018-12-19 13:43:42 +01:00
bus ARM: SoC driver updates 2018-12-31 17:32:35 -08:00
cdrom gdrom: fix a memory leak bug 2018-12-29 08:20:44 -07:00
char Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
clk Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2019-01-02 18:56:59 -08:00
clocksource arch/csky patches for 4.21-rc1 2019-01-05 09:50:07 -08:00
connector
cpufreq powerpc updates for 4.21 2018-12-27 10:43:24 -08:00
cpuidle powerpc updates for 4.21 2018-12-27 10:43:24 -08:00
crypto Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
dax mm, devm_memremap_pages: fix shutdown handling 2018-12-28 12:11:47 -08:00
dca
devfreq
dio
dma Merge branch 'next/drivers' into next/late 2019-01-04 14:31:38 -08:00
dma-buf drivers/dma-buf/udmabuf.c: convert to use vm_fault_t 2019-01-04 13:13:46 -08:00
edac EDAC, fsl_ddr: Add LS1021A to the list of supported hardware 2018-12-19 11:57:45 +01:00
eisa
extcon
firewire FireWire (IEEE 1394) subsystem patch: 2019-01-05 18:33:21 -08:00
firmware arm64 fixes for -rc1 2019-01-05 11:28:39 -08:00
fmc
fpga Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
fsi
gnss
gpio This is the bulk of GPIO changes for the v4.21 kernel series: 2018-12-28 20:00:21 -08:00
gpu drm i915 gvt, amdgpu, core fixes 2019-01-05 18:25:19 -08:00
hid Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid 2019-01-05 17:53:40 -08:00
hsi
hv Char/Misc driver patches for 4.21-rc1 2018-12-28 20:54:57 -08:00
hwmon Kconfig updates for v4.21 2018-12-29 13:03:29 -08:00
hwspinlock hwspinlock: fix return value check in stm32_hwspinlock_probe() 2019-01-03 11:42:10 -08:00
hwtracing intel_th: msu: Fix an off-by-one in attribute store 2018-12-19 20:21:06 +01:00
i2c Merge branch 'i2c/for-5.0' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2019-01-05 18:13:35 -08:00
i3c
ide for-4.21/block-20181221 2018-12-28 13:19:59 -08:00
idle
iio Staging/IIO driver patches for 4.21-rc1 2018-12-28 20:39:58 -08:00
infiniband 4.21 merge window 2nd pull request 2019-01-05 18:20:51 -08:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2019-01-02 18:56:59 -08:00
iommu IOMMU Updates for Linux v4.21 2019-01-01 15:55:29 -08:00
ipack
irqchip Xtensa updates for v4.21: 2018-12-29 09:40:40 -08:00
isdn isdn: fix kernel-infoleak in capi_unlocked_ioctl 2019-01-02 10:31:39 -08:00
leds LEDs for 4.21-rc1 2018-12-25 14:52:50 -08:00
lightnvm lightnvm: pblk: fix use-after-free bug 2018-12-22 14:45:35 -07:00
macintosh Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
mailbox mailbox: tegra-hsp: Use device-managed registration API 2018-12-21 22:31:26 -06:00
mcb
md dm: fix redundant IO accounting for bios that need splitting 2019-01-21 11:29:27 -05:00
media Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
memory ARM: SoC: late updates 2019-01-05 11:30:37 -08:00
memstick MMC core: 2018-12-28 16:52:18 -08:00
message
mfd
misc Merge branch 'i2c/for-5.0' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2019-01-05 18:13:35 -08:00
mmc MMC core: 2018-12-28 16:52:18 -08:00
mtd Kbuild updates for v4.21 2018-12-29 12:03:17 -08:00
mux
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-03 12:53:47 -08:00
nfc
ntb
nubus
nvdimm Merge branch 'akpm' (patches from Andrew) 2018-12-28 16:55:46 -08:00
nvme
nvmem
of Merge tag 'devicetree-for-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux 2018-12-28 20:08:34 -08:00
opp
oprofile
parisc Kconfig file consolidation for v4.21 2018-12-29 13:40:29 -08:00
parport
pci pci-v4.21-changes 2019-01-05 17:57:34 -08:00
pcmcia Included in this update: 2019-01-05 11:23:17 -08:00
perf drivers/perf: hisi: Fixup one DDRC PMU register offset 2019-01-04 10:13:27 +00:00
phy
pinctrl Pin control bulk changes for the v4.21 kernel cycle: 2019-01-01 13:19:16 -08:00
platform chrome platform changes for v4.21 2019-01-06 11:40:06 -08:00
pnp Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
power power supply and reset changes for the v4.21 series 2018-12-28 20:22:45 -08:00
powercap
pps Kconfig updates for v4.21 2018-12-29 13:03:29 -08:00
ps3
ptp Char/Misc driver patches for 4.21-rc1 2018-12-28 20:54:57 -08:00
pwm pwm: imx: Add ipg clock operation 2018-12-24 12:06:56 +01:00
rapidio
ras treewide: surround Kconfig file paths with double quotes 2018-12-22 00:25:54 +09:00
regulator Merge remote-tracking branch 'regulator/topic/coupled' into regulator-next 2018-12-21 13:43:35 +00:00
remoteproc
reset
rpmsg
rtc RTC for 4.21 2019-01-01 13:24:31 -08:00
s390 s390 updates for the 4.21 merge window 2019-01-02 18:37:01 -08:00
sbus Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next 2018-12-26 10:32:18 -08:00
scsi Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
sfi
sh
siox
slimbus
sn
soc ARM: SoC driver updates 2018-12-31 17:32:35 -08:00
soundwire
spi spi: Updates for v4.21 2018-12-25 14:43:54 -08:00
spmi
ssb
staging Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
target SCSI misc on 20181224 2018-12-28 14:48:06 -08:00
tc
tee OP-TEE dynamic shm log message 2018-12-31 13:06:30 -08:00
thermal Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2019-01-05 16:07:28 -08:00
thunderbolt
tty ARM: SoC: late updates 2019-01-05 11:30:37 -08:00
uio Char/Misc driver patches for 4.21-rc1 2018-12-28 20:54:57 -08:00
usb pci-v4.21-changes 2019-01-05 17:57:34 -08:00
uwb
vfio IOMMU Updates for Linux v4.21 2019-01-01 15:55:29 -08:00
vhost Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
video fbdev changes for v4.21: 2019-01-05 18:15:37 -08:00
virt
virtio virtio, vhost: features, fixes, cleanups 2019-01-02 18:54:45 -08:00
visorbus
vlynq
vme
w1 treewide: surround Kconfig file paths with double quotes 2018-12-22 00:25:54 +09:00
watchdog linux-watchdog 4.21-rc1 tag 2019-01-01 13:16:45 -08:00
xen Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
zorro
Kconfig Kconfig file consolidation for v4.21 2018-12-29 13:40:29 -08:00
Makefile