linux/Documentation
Linus Torvalds 088737f44b Writeback error handling fixes (pile #2)
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Merge tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux

Pull Writeback error handling updates from Jeff Layton:
 "This pile represents the bulk of the writeback error handling fixes
  that I have for this cycle. Some of the earlier patches in this pile
  may look trivial but they are prerequisites for later patches in the
  series.

  The aim of this set is to improve how we track and report writeback
  errors to userland. Most applications that care about data integrity
  will periodically call fsync/fdatasync/msync to ensure that their
  writes have made it to the backing store.

  For a very long time, we have tracked writeback errors using two flags
  in the address_space: AS_EIO and AS_ENOSPC. Those flags are set when a
  writeback error occurs (via mapping_set_error) and are cleared as a
  side-effect of filemap_check_errors (as you noted yesterday). This
  model really sucks for userland.

  Only the first task to call fsync (or msync or fdatasync) will see the
  error. Any subsequent task calling fsync on a file will get back 0
  (unless another writeback error occurs in the interim). If I have
  several tasks writing to a file and calling fsync to ensure that their
  writes got stored, then I need to have them coordinate with one
  another. That's difficult enough, but in a world of containerized
  setups that coordination may even not be possible.

  But wait...it gets worse!

  The calls to filemap_check_errors can be buried pretty far down in the
  call stack, and there are internal callers of filemap_write_and_wait
  and the like that also end up clearing those errors. Many of those
  callers ignore the error return from that function or return it to
  userland at nonsensical times (e.g. truncate() or stat()). If I get
  back -EIO on a truncate, there is no reason to think that it was
  because some previous writeback failed, and a subsequent fsync() will
  (incorrectly) return 0.

  This pile aims to do three things:

   1) ensure that when a writeback error occurs that that error will be
      reported to userland on a subsequent fsync/fdatasync/msync call,
      regardless of what internal callers are doing

   2) report writeback errors on all file descriptions that were open at
      the time that the error occurred. This is a user-visible change,
      but I think most applications are written to assume this behavior
      anyway. Those that aren't are unlikely to be hurt by it.

   3) document what filesystems should do when there is a writeback
      error. Today, there is very little consistency between them, and a
      lot of cargo-cult copying. We need to make it very clear what
      filesystems should do in this situation.

  To achieve this, the set adds a new data type (errseq_t) and then
  builds new writeback error tracking infrastructure around that. Once
  all of that is in place, we change the filesystems to use the new
  infrastructure for reporting wb errors to userland.

  Note that this is just the initial foray into cleaning up this mess.
  There is a lot of work remaining here:

   1) convert the rest of the filesystems in a similar fashion. Once the
      initial set is in, then I think most other fs' will be fairly
      simple to convert. Hopefully most of those can in via individual
      filesystem trees.

   2) convert internal waiters on writeback to use errseq_t for
      detecting errors instead of relying on the AS_* flags. I have some
      draft patches for this for ext4, but they are not quite ready for
      prime time yet.

  This was a discussion topic this year at LSF/MM too. If you're
  interested in the gory details, LWN has some good articles about this:

      https://lwn.net/Articles/718734/
      https://lwn.net/Articles/724307/"

* tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  btrfs: minimal conversion to errseq_t writeback error reporting on fsync
  xfs: minimal conversion to errseq_t writeback error reporting
  ext4: use errseq_t based error handling for reporting data writeback errors
  fs: convert __generic_file_fsync to use errseq_t based reporting
  block: convert to errseq_t based writeback error tracking
  dax: set errors in mapping when writeback fails
  Documentation: flesh out the section in vfs.txt on storing and reporting writeback errors
  mm: set both AS_EIO/AS_ENOSPC and errseq_t in mapping_set_error
  fs: new infrastructure for writeback error handling and reporting
  lib: add errseq_t type and infrastructure for handling it
  mm: don't TestClearPageError in __filemap_fdatawait_range
  mm: clear AS_EIO/AS_ENOSPC when writeback initiation fails
  jbd2: don't clear and reset errors after waiting on writeback
  buffer: set errors in mapping at the time that the error occurs
  fs: check for writeback errors after syncing out buffers in generic_file_fsync
  buffer: use mapping_set_error instead of setting the flag
  mm: fix mapping_set_error call in me_pagecache_dirty
2017-07-07 19:38:17 -07:00
..
ABI DeviceTree for 4.13: 2017-07-07 10:37:54 -07:00
accounting
acpi This is the bulk of GPIO changes for the v4.13 series: 2017-07-07 12:40:27 -07:00
admin-guide Merge branch 'akpm' (patches from Andrew) 2017-07-06 22:27:08 -07:00
aoe
arm ARM: at91: Documentation: add armv7m families 2017-06-02 10:11:09 +02:00
arm64 arm64: Add workaround for Cavium Thunder erratum 30115 2017-06-15 09:45:04 +01:00
auxdisplay
backlight
blackfin samples: move blackfin gptimers-example from Documentation 2016-10-10 07:12:02 -06:00
block block: remove bio_clone() and all references. 2017-06-18 12:40:59 -06:00
blockdev remove the mg_disk driver 2017-04-14 14:00:49 -06:00
bus-devices
cdrom cdrom: Make device operations read-only 2017-02-14 08:29:56 -07:00
cgroup-v1 Merge branch 'for-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2017-02-27 21:41:08 -08:00
cma
connector
console
core-api There has been a fair amount of activity in the docs tree this time 2017-07-03 21:13:25 -07:00
cpu-freq cpufreq: intel_pstate: Document the current behavior and user interface 2017-05-14 02:06:03 +02:00
cpuidle
cris
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-07-05 12:22:23 -07:00
dev-tools linux-kselftest-4.13-rc1-update 2017-07-07 14:04:47 -07:00
device-mapper dm zoned: drive-managed zoned block device target 2017-06-19 11:05:20 -04:00
devicetree Merge (most of) tag 'mfd-next-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd 2017-07-07 13:30:05 -07:00
dmaengine dmaengine: Documentation: Fix typo in pxa_dma.txt 2016-11-14 08:14:24 +05:30
doc-guide kernel-doc: describe the `literal` syntax 2017-05-16 08:44:24 -03:00
driver-api This is the big bulk of pin control changes for the v4.13 series: 2017-07-06 11:38:59 -07:00
driver-model This is the first pull request for the new dma-mapping subsystem 2017-07-06 19:20:54 -07:00
early-userspace Documentation: Fix dead URLs to ftp.kernel.org 2017-03-29 15:46:06 -06:00
EDID drm: use .hword to represent 16-bit numbers 2017-03-30 10:15:19 +02:00
extcon extcon: Remove porting compatibility of swich class 2017-04-06 10:55:24 +09:00
fault-injection
fb docs: update old references for DocBook from the documentation 2017-05-16 08:44:19 -03:00
features powerpc updates for 4.12 part 1. 2017-05-05 11:36:44 -07:00
filesystems Writeback error handling fixes (pile #2) 2017-07-07 19:38:17 -07:00
firmware_class firmware: revamp firmware documentation 2017-01-11 09:42:59 +01:00
fmc
fpga fpga: Add scatterlist based programming 2017-02-10 15:20:44 +01:00
frv docs: fix locations of several documents that got moved 2016-10-24 08:12:35 -02:00
gpio gpio: return NULL from gpiod_get_optional when GPIOLIB is disabled 2017-03-15 11:16:30 +01:00
gpu docs: update old references for DocBook from the documentation 2017-05-16 08:44:19 -03:00
hid Documentation: hid: fix path to input bus definitions 2017-03-13 17:15:19 -06:00
hwmon hwmon: (pmbus) move header file out of I2C realm 2017-06-11 17:08:19 -07:00
i2c i2c: i801: Add support for Intel Gemini Lake 2017-02-09 17:39:16 +01:00
ia64
ide
iio
infiniband IB/opa-vnic: Virtual Network Interface Controller (VNIC) documentation 2017-04-20 12:01:06 -04:00
input Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2017-05-26 16:45:13 -07:00
ioctl scsi: cxlflash: Introduce host ioctl support 2017-06-26 15:01:11 -04:00
isdn docs: fix locations of several documents that got moved 2016-10-24 08:12:35 -02:00
kbuild Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
kdump Documentation: kdump: describe arm64 port 2017-04-05 18:32:32 +01:00
kernel-hacking There has been a fair amount of activity in the docs tree this time 2017-07-03 21:13:25 -07:00
laptops platform/x86: thinkpad_acpi: Add support for X1 Yoga (2016) Tablet Mode 2016-12-13 09:29:06 -08:00
leds Documentaion: leds: leds-lp55xx.txt: Fix typos 2017-03-17 13:06:14 -06:00
lightnvm lightnvm: physical block device (pblk) target 2017-04-16 10:06:33 -06:00
livepatch livepatch: allow removal of a disabled patch 2017-03-08 09:38:43 +01:00
locking locking/ww_mutex/Documentation: Update the design document 2017-01-14 11:14:55 +01:00
m68k docs: fix locations of several documents that got moved 2016-10-24 08:12:35 -02:00
md Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 2017-05-03 10:05:38 -07:00
media media updates for v4.13-rc1 2017-07-06 11:15:19 -07:00
memory-devices
metag
mic
mips
misc-devices Documentation: misc-devices: Add Documentation for pci-endpoint-test driver 2017-04-28 10:23:19 -05:00
mmc MMC core: 2017-05-02 17:34:32 -07:00
mn10300
mtd spi-nor: Add support for Intel SPI serial flash controller 2017-01-03 17:33:36 +00:00
namespaces
netlabel
networking Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-07-05 12:31:59 -07:00
nfc
nios2
nvdimm
nvmem
parisc
PCI docs: update old references for DocBook from the documentation 2017-05-16 08:44:19 -03:00
pcmcia
perf perf: qcom: Add L3 cache PMU driver 2017-04-03 18:53:50 +01:00
phy
platform
power power supply and reset changes for the v4.13 series 2017-07-04 14:25:14 -07:00
powerpc powerpc updates for 4.13 2017-07-07 13:55:45 -07:00
pps Doc: clarify source of jitter in USB1.1, and USB2.0 2017-01-04 14:40:52 -07:00
process Kbuild thin archives updates for v4.13 2017-07-07 15:11:12 -07:00
pti
ptp
rapidio
RCU rcu: Remove debugfs tracing 2017-06-08 18:52:43 -07:00
s390 docs: add documentation for vfio-ccw 2017-03-31 12:55:11 +02:00
scheduler sched/deadline: Add documentation about GRUB reclaiming 2017-06-08 10:31:56 +02:00
scsi scsi: make asynchronous aborts mandatory 2017-04-06 13:07:33 -04:00
security docs: Fix some formatting issues in request-key.rst 2017-05-18 10:46:25 -06:00
serial tty: n_gsm: do not send/receive in ldisc close path 2017-06-03 18:48:52 +09:00
sh docs-rst: convert sh book to ReST 2017-05-16 08:44:18 -03:00
sound sound updates for 4.13-rc1 2017-07-06 10:56:51 -07:00
sparc Documentation/sparc: Steps for sending break on sunhv console 2017-02-23 08:27:25 -08:00
sphinx Docs: clean up some DocBook loose ends 2017-06-23 14:17:38 -06:00
sphinx-static
spi spi: Document SPI slave controller support 2017-05-26 13:11:00 +01:00
sysctl Replace 2 jiffies with sysctl netdev_budget_usecs to enable softirq tuning 2017-04-21 13:22:34 -04:00
target Documentation/target: add an example script to configure an iSCSI target 2017-05-01 22:21:35 -07:00
thermal Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2017-05-12 11:58:45 -07:00
timers rcu: Eliminate NOCBs CPU-state Kconfig options 2017-06-08 18:52:43 -07:00
trace Char/Misc patches for 4.13-rc1 2017-07-03 20:55:59 -07:00
translations doc/kokr/howto: Only send regression fixes after -rc1 2017-06-22 10:25:22 -06:00
usb usb: gadget: add f_uac1 variant based on a new u_audio api 2017-06-19 09:22:47 +03:00
userspace-api doc: ReSTify no_new_privs.txt 2017-05-18 10:30:09 -06:00
virtual kvm: x86: mmu: allow A/D bits to be disabled in an mmu 2017-07-03 11:19:54 +02:00
vm ksm: introduce ksm_max_page_sharing per page deduplication limit 2017-07-06 16:24:31 -07:00
w1 w1: add documentation for w1_ds2438 2017-03-17 15:10:49 +09:00
watchdog iTCO_wdt: all versions count down twice 2017-05-19 10:42:11 +02:00
wimax
x86 x86/mce: Update bootlog description to reflect behavior on AMD 2017-06-14 07:32:10 +02:00
xtensa of: update ePAPR references to point to Devicetree Specification 2017-06-22 11:22:06 -05:00
.gitignore
00-INDEX linux-kselftest-4.13-rc1-update 2017-07-07 14:04:47 -07:00
bcache.txt
bt8xxgpio.txt
btmrvl.txt
bus-virt-phys-mapping.txt
cachetlb.txt
cgroup-v2.txt mm/oom_kill: count global and memory cgroup oom kills 2017-07-06 16:24:35 -07:00
Changes docs: add back 'Documentation/Changes' file (as symlink) 2016-12-14 16:30:12 -08:00
circular-buffers.txt Documentation: circular-buffers: use READ_ONCE() 2016-11-16 16:17:45 -07:00
clk.txt
CodingStyle doc: re-add CodingStyle and SubmittingPatches 2016-10-24 08:12:35 -02:00
conf.py Docs: Fix breakage with Sphinx 1.5 and upper 2017-06-23 13:45:37 -06:00
cpu-load.txt
cputopology.txt docs: Fix a couple typos 2017-04-27 15:54:39 -06:00
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt docs: Fix a couple typos 2017-04-27 15:54:39 -06:00
dell_rbu.txt
digsig.txt
DMA-API-HOWTO.txt dma-mapping: remove DMA_ERROR_CODE 2017-06-28 06:54:37 -07:00
DMA-API.txt Documentation: DMA API: fix a typo in a function name 2017-06-05 15:57:02 -06:00
DMA-attributes.txt common: DMA-mapping: add DMA_ATTR_PRIVILEGED attribute 2017-01-19 15:56:19 +00:00
DMA-ISA-LPC.txt Documentation: DMA-ISA-LPC.txt 2017-02-12 15:20:07 -07:00
docutils.conf
dontdiff GCC plugin updates: 2017-07-05 11:46:59 -07:00
efi-stub.txt
eisa.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcc-plugins.txt gcc-plugins: update architecture list in documentation 2017-03-21 22:20:05 +11:00
highuid.txt
hw_random.txt
hwspinlock.txt
index.rst Make the main documentation title less Geocities 2017-06-23 14:02:27 -06:00
intel_txt.txt
Intel-IOMMU.txt
io_ordering.txt
io-mapping.txt
iostats.txt
IPMI.txt Documentation: Fix a typo in IPMI.txt. 2017-01-05 15:01:54 -06:00
IRQ-affinity.txt
IRQ-domain.txt Documentation: Update IRQ-domain.txt to document irq_domain_mapping 2017-05-22 22:29:45 +02:00
IRQ.txt
irqflags-tracing.txt
isa.txt
isapnp.txt
kernel-doc-nano-HOWTO.txt docs: update old references for DocBook from the documentation 2017-05-16 08:44:19 -03:00
kernel-per-CPU-kthreads.txt rcu: Eliminate NOCBs CPU-state Kconfig options 2017-06-08 18:52:43 -07:00
kobject.txt
kprobes.txt
kref.txt Revert "kref: double kref_put() in my_data_handler()" 2017-04-08 18:38:10 +02:00
ldm.txt
lockup-watchdogs.txt docs: fix locations of several documents that got moved 2016-10-24 08:12:35 -02:00
logo.gif
logo.txt
lsm.txt docs-rst: convert lsm from DocBook to ReST 2017-05-16 08:44:19 -03:00
lzo.txt
mailbox.txt
Makefile docs: remove DocBook from the building system 2017-05-16 08:44:19 -03:00
memory-barriers.txt There has been a fair amount of activity in the docs tree this time 2017-07-03 21:13:25 -07:00
memory-hotplug.txt scripts/spelling.txt: add "followings" pattern and fix typo instances 2017-02-27 18:43:47 -08:00
men-chameleon-bus.txt
nommu-mmap.txt
ntb.txt
numastat.txt
padata.txt
parport-lowlevel.txt
percpu-rw-semaphore.txt
phy.txt Documentation: phy: Fix repetition of word 'the' 2017-03-09 00:33:15 -07:00
pi-futex.txt
pnp.txt
preempt-locking.txt
printk-formats.txt vsprintf: Add %p extension "%pOF" for device tree 2017-06-27 12:36:40 -05:00
pwm.txt
rbtree.txt
remoteproc.txt
rfkill.txt docs: fix locations of several documents that got moved 2016-10-24 08:12:35 -02:00
robust-futex-ABI.txt
robust-futexes.txt
rpmsg.txt
rtc.txt
SAK.txt
sgi-ioc4.txt
siphash.txt siphash: implement HalfSipHash1-3 for hash tables 2017-01-09 13:58:57 -05:00
SM501.txt
smsc_ece1099.txt
static-keys.txt docs: Fix a couple typos 2017-04-27 15:54:39 -06:00
SubmittingPatches doc: re-add CodingStyle and SubmittingPatches 2016-10-24 08:12:35 -02:00
svga.txt
switchtec.txt switchtec: Add IOCTLs to the Switchtec driver 2017-04-12 12:23:37 -05:00
sync_file.txt Documentation: sync_file.txt: Fix typos 2017-03-17 13:03:36 -06:00
tee.txt Documentation: tee subsystem and op-tee driver 2017-03-10 14:51:57 +01:00
this_cpu_ops.txt
unaligned-memory-access.txt Documentation/unaligned-memory-access.txt: fix incorrect comparison operator 2016-12-27 13:08:42 -07:00
vfio-mediated-device.txt docs: Fix a spelling error in vfio-mediated-device.txt 2017-04-27 15:54:39 -06:00
vfio.txt
video-output.txt
xillybus.txt
xz.txt
zorro.txt docs: Fix a couple typos 2017-04-27 15:54:39 -06:00