DIR_INDEX has been introduced as a compat ext4 feature. That means that
even kernels / tools that don't understand the feature may modify the
filesystem. This works because for kernels not understanding indexed dir
format, internal htree nodes appear just as empty directory entries.
Index dir aware kernels then check the htree structure is still
consistent before using the data. This all worked reasonably well until
metadata checksums were introduced. The problem is that these
effectively made DIR_INDEX only ro-compatible because internal htree
nodes store checksums in a different place than normal directory blocks.
Thus any modification ignorant to DIR_INDEX (or just clearing
EXT4_INDEX_FL from the inode) will effectively cause checksum mismatch
and trigger kernel errors. So we have to be more careful when dealing
with indexed directories on filesystems with checksumming enabled.

1) We just disallow loading any directory inodes with EXT4_INDEX_FL when
DIR_INDEX is not enabled. This is harsh but it should be very rare (it
means someone disabled DIR_INDEX on existing filesystem and didn't run
e2fsck), e2fsck can fix the problem, and we don't want to answer the
difficult question: "Should we rather corrupt the directory more or
should we ignore that DIR_INDEX feature is not set?"

2) When we find out htree structure is corrupted (but the filesystem and
the directory should in support htrees), we continue just ignoring htree
information for reading but we refuse to add new entries to the
directory to avoid corrupting it more.

Link: https://lore.kernel.org/r/20200210144316.22081-1-jack@suse.cz
Fixes: dbe89444 ("ext4: Calculate and verify checksums for htree nodes")
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

A recent commit, 9803387c ("ext4: validate the
debug_want_extra_isize mount option at parse time"), moved mount-time
checks around.  One of those changes moved the inode size check before
the blocksize variable was set to the blocksize of the file system.
After 9803387c was set to the minimum allowable blocksize, which
in practice on most systems would be 1024 bytes.  This cuased file
systems with inode sizes larger than 1024 bytes to be rejected with a
message:

EXT4-fs (sdXX): unsupported inode size: 4096

Fixes: 9803387c ("ext4: validate the debug_want_extra_isize mount option at parse time")
Link: https://lore.kernel.org/r/20200206225252.GA3673@mit.eduReported-by: Herbert Poetzl <herbert@13thfloor.at>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

Coverity reports that conditions checking quota limits in ext4_statfs()
contain dead code. Indeed it is right and current conditions can be
simplified.

Link: https://lore.kernel.org/r/20200130111148.10766-1-jack@suse.czReported-by: Coverity <scan-admin@coverity.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

Don't assume that the mmp_nodename and mmp_bdevname strings are NUL
terminated, since they are filled in by snprintf(), which is not
guaranteed to do so.

Link: https://lore.kernel.org/r/1580076215-1048-1-git-send-email-adilger@dilger.caSigned-off-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

Pull ext4 updates from Ted Ts'o:
 "This merge window, we've added some performance improvements in how we
  handle inode locking in the read/write paths, and improving the
  performance of Direct I/O overwrites.

  We also now record the error code which caused the first and most
  recent ext4_error() report in the superblock, to make it easier to
  root cause problems in production systems.

  There are also many of the usual cleanups and miscellaneous bug fixes"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (49 commits)
  jbd2: clean __jbd2_journal_abort_hard() and __journal_abort_soft()
  jbd2: make sure ESHUTDOWN to be recorded in the journal superblock
  ext4, jbd2: ensure panic when aborting with zero errno
  jbd2: switch to use jbd2_journal_abort() when failed to submit the commit record
  jbd2_seq_info_next should increase position index
  jbd2: remove pointless assertion in __journal_remove_journal_head
  ext4,jbd2: fix comment and code style
  jbd2: delete the duplicated words in the comments
  ext4: fix extent_status trace points
  ext4: fix symbolic enum printing in trace output
  ext4: choose hardlimit when softlimit is larger than hardlimit in ext4_statfs_project()
  ext4: fix race conditions in ->d_compare() and ->d_hash()
  ext4: make dioread_nolock the default
  ext4: fix extent_status fragmentation for plain files
  jbd2: clear JBD2_ABORT flag before journal_reset to update log tail info when load journal
  ext4: drop ext4_kvmalloc()
  ext4: Add EXT4_IOC_FSGETXATTR/EXT4_IOC_FSSETXATTR to compat_ioctl
  ext4: remove unused macro MPAGE_DA_EXTENT_TAIL
  ext4: add missing braces in ext4_ext_drop_refs()
  ext4: fix some nonstandard indentation in extents.c
  ...

Pull drm updates from Davbe Airlie:
 "This is the main pull request for graphics for 5.6. Usual selection of
  changes all over.

  I've got one outstanding vmwgfx pull that touches mm so kept it
  separate until after all of this lands. I'll try and get it to you
  soon after this, but it might be early next week (nothing wrong with
  code, just my schedule is messy)

  This also hits a lot of fbdev drivers with some cleanups.

  Other notables:
   - vulkan timeline semaphore support added to syncobjs
   - nouveau turing secureboot/graphics support
   - Displayport MST display stream compression support

  Detailed summary:

  uapi:
   - dma-buf heaps added (and fixed)
   - command line add support for panel oreientation
   - command line allow overriding penguin count

  drm:
   - mipi dsi definition updates
   - lockdep annotations for dma_resv
   - remove dma-buf kmap/kunmap support
   - constify fb_ops in all fbdev drivers
   - MST fix for daisy chained hotplug-
   - CTA-861-G modes with VIC >= 193 added
   - fix drm_panel_of_backlight export
   - LVDS decoder support
   - more device based logging support
   - scanline alighment for dumb buffers
   - MST DSC helpers

  scheduler:
   - documentation fixes
   - job distribution improvements

  panel:
   - Logic PD type 28 panel support
   - Jimax8729d MIPI-DSI
   - igenic JZ4770
   - generic DSI devicetree bindings
   - sony acx424AKP panel
   - Leadtek LTK500HD1829
   - xinpeng XPP055C272
   - AUO B116XAK01
   - GiantPlus GPM940B0
   - BOE NV140FHM-N49
   - Satoz SAT050AT40H12R2
   - Sharp LS020B1DD01D panels.

  ttm:
   - use blocking WW lock

  i915:
   - hw/uapi state separation
   - Lock annotation improvements
   - selftest improvements
   - ICL/TGL DSI VDSC support
   - VBT parsing improvments
   - Display refactoring
   - DSI updates + fixes
   - HDCP 2.2 for CFL
   - CML PCI ID fixes
   - GLK+ fbc fix
   - PSR fixes
   - GEN/GT refactor improvments
   - DP MST fixes
   - switch context id alloc to xarray
   - workaround updates
   - LMEM debugfs support
   - tiled monitor fixes
   - ICL+ clock gating programming removed
   - DP MST disable sequence fixed
   - LMEM discontiguous object maps
   - prefaulting for discontiguous objects
   - use LMEM for dumb buffers if possible
   - add LMEM mmap support

  amdgpu:
   - enable sync object timelines for vulkan
   - MST atomic routines
   - enable MST DSC support
   - add DMCUB display microengine support
   - DC OEM i2c support
   - Renoir DC fixes
   - Initial HDCP 2.x support
   - BACO support for Arcturus
   - Use BACO for runtime PM power save
   - gfxoff on navi10
   - gfx10 golden updates and fixes
   - DCN support on POWER
   - GFXOFF for raven1 refresh
   - MM engine idle handlers cleanup
   - 10bpc EDP panel fixes
   - renoir watermark fixes
   - SR-IOV fixes
   - Arcturus VCN fixes
   - GDDR6 training fixes
   - freesync fixes
   - Pollock support

  amdkfd:
   - unify more codepath with amdgpu
   - use KIQ to setup HIQ rather than MMIO

  radeon:
   - fix vma fault handler race
   - PPC DMA fix
   - register check fixes for r100/r200

  nouveau:
   - mmap_sem vs dma_resv fix
   - rewrite the ACR secure boot code for Turing
   - TU10x graphics engine support (TU11x pending)
   - Page kind mapping for turing
   - 10-bit LUT support
   - GP10B Tegra fixes
   - HD audio regression fix

  hisilicon/hibmc:
   - use generic fbdev code and helpers

  rockchip:
   - dsi/px30 support

  virtio:
   - fb damage support
   - static some functions

  vc4:
   - use dma_resv lock wrappers

  msm:
   - use dma_resv lock wrappers
   - sc7180 display + DSI support
   - a618 support
   - UBWC support improvements

  vmwgfx:
   - updates + new logging uapi

  exynos:
   - enable/disable callback cleanups

  etnaviv:
   - use dma_resv lock wrappers

  atmel-hlcdc:
   - clock fixes

  mediatek:
   - cmdq support
   - non-smooth cursor fixes
   - ctm property support

  sun4i:
   - suspend support
   - A64 mipi dsi support

  rcar-du:
   - Color management module support
   - LVDS encoder dual-link support
   - R8A77980 support

  analogic:
   - add support for an6345

  ast:
   - atomic modeset support
   - primary plane garbage fix

  arcgpu:
   - fixes for fourcc handling

  tegra:
   - minor fixes and improvments

  mcde:
   - vblank support

  meson:
   - OSD1 plane AFBC commit

  gma500:
   - add pageflip support
   - reomve global drm_dev

  komeda:
   - tweak debugfs output
   - d32 support
   - runtime PM suppotr

  udl:
   - use generic shmem helpers
   - cleanup and fixes"

* tag 'drm-next-2020-01-30' of git://anongit.freedesktop.org/drm/drm: (1998 commits)
  drm/nouveau/fb/gp102-: allow module to load even when scrubber binary is missing
  drm/nouveau/acr: return error when registering LSF if ACR not supported
  drm/nouveau/disp/gv100-: not all channel types support reporting error codes
  drm/nouveau/disp/nv50-: prevent oops when no channel method map provided
  drm/nouveau: support synchronous pushbuf submission
  drm/nouveau: signal pending fences when channel has been killed
  drm/nouveau: reject attempts to submit to dead channels
  drm/nouveau: zero vma pointer even if we only unreference it rather than free
  drm/nouveau: Add HD-audio component notifier support
  drm/nouveau: fix build error without CONFIG_IOMMU_API
  drm/nouveau/kms/nv04: remove set but not used variable 'width'
  drm/nouveau/kms/nv50: remove set but not unused variable 'nv_connector'
  drm/nouveau/mmu: fix comptag memory leak
  drm/nouveau/gr/gp10b: Use gp100_grctx and gp100_gr_zbc
  drm/nouveau/pmu/gm20b,gp10b: Fix Falcon bootstrapping
  drm/exynos: Rename Exynos to lowercase
  drm/exynos: change callback names
  drm/mst: Don't do atomic checks over disabled managers
  drm/amdgpu: add the lost mutex_init back
  drm/amd/display: skip opp blank or unblank if test pattern enabled
  ...

Pull power supply and reset updates from Sebastian Reichel:
 "Core:
   - Add battery internal resistance temperature table support

  Drivers:
   - sc27xx: Optimize the battery resistance with measuring temperature
   - max17042-battery: Add MAX17055 support
   - bq25890-charger: Add support of BQ25892 and BQ25896 chips
   - misc fixes"

* tag 'for-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power-supply: (44 commits)
  power: supply: ipaq_micro_battery: remove unneeded semicolon
  power: supply: bq25890_charger: fix incorrect error return when bq25890_field_read fails
  power: supply: axp20x_usb_power: Only poll while offline
  power: supply: axp20x_usb_power: Add wakeup control
  power: supply: axp20x_usb_power: Allow offlining
  power: supply: axp20x_usb_power: Use a match structure
  power: suppy: ucs1002: Make the symbol 'ucs1002_regulator_enable' static
  power: reset: at91-poweroff: use proper master clock register offset
  power: reset: at91-poweroff: introduce struct shdwc_reg_config
  power: supply: bq25890_charger: Add DT and I2C ids for all supported chips
  dt-bindings: Add new chips to bq25890 binding documentation
  power: supply: bq25890_charger: Add support of BQ25892 and BQ25896 chips
  power: supply: core: Update sysfs-class-power ABI document
  power: supply: sbs-battery: Fix a signedness bug in sbs_get_battery_capacity()
  power: supply: ltc2941-battery-gauge: fix use-after-free
  power: supply: max17040: Correct IRQ wake handling
  power: supply: axp20x_usb_power: Remove unused device_node
  power: supply: axp20x_ac_power: Add wakeup control
  power: supply: axp20x_ac_power: Allow offlining
  power: supply: axp20x_ac_power: Fix reporting online status
  ...

Pull devicetree updates from Rob Herring:

 - Update dtc to upstream v1.5.1-22-gc40aeb60b47a (plus 1 revert)

 - Fix for DMA coherent devices on Power

 - Rework and simplify the DT phandle cache code

 - DT schema conversions for LEDS, gpio-leds, STM32 dfsdm, STM32 UART,
   STM32 ROMEM, STM32 watchdog, STM32 DMAs, STM32 mlahb, STM32 RTC,
   STM32 RCC, STM32 syscon, rs485, Renesas rCar CSI2, Faraday FTIDE010,
   DWC2, Arm idle-states, Allwinner legacy resets, PRCM and clocks,
   Allwinner H6 OPP, Allwinner AHCI, Allwinner MBUS, Allwinner A31 CSI,
   Allwinner h/w codec, Allwinner A10 system ctrl, Allwinner SRAM,
   Allwinner USB PHY, Renesas CEU, generic PCI host, Arm Versatile PCI

 - New binding schemas for SATA and PATA controllers, TI and Infineon VR
   controllers, MAX31730

 - New compatible strings for i.MX8QM, WCN3991, renesas,r8a77961-wdt,
   renesas,etheravb-r8a77961

 - Add USB 'super-speed-plus' as a documented speed

 - Vendor prefixes for broadmobi, calaosystems, kam, and mps

 - Clean-up the multiple flavors of ST-Ericsson vendor prefixes

* tag 'devicetree-for-5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux: (66 commits)
  scripts/dtc: Revert "yamltree: Ensure consistent bracketing of properties with phandles"
  of: Add OF_DMA_DEFAULT_COHERENT & select it on powerpc
  dt-bindings: leds: Convert gpio-leds to DT schema
  dt-bindings: leds: Convert common LED binding to schema
  dt-bindings: PCI: Convert generic host binding to DT schema
  dt-bindings: PCI: Convert Arm Versatile binding to DT schema
  dt-bindings: Be explicit about installing deps
  dt-bindings: stm32: convert dfsdm to json-schema
  dt-bindings: serial: Convert STM32 UART to json-schema
  dt-bindings: serial: Convert rs485 bindings to json-schema
  dt-bindings: timer: Use non-empty ranges in example
  dt-bindings: arm-boards: typo fix
  dt-bindings: Add TI and Infineon VR Controllers as trivial devices
  dt-binding: usb: add "super-speed-plus"
  dt-bindings: rcar-csi2: Convert bindings to json-schema
  dt-bindings: iio: adc: ad7606: Fix wrong maxItems value
  dt-bindings: Convert Faraday FTIDE010 to DT schema
  dt-bindings: Create DT bindings for PATA controllers
  dt-bindings: Create DT bindings for SATA controllers
  dt: bindings: add vendor prefix for Kamstrup A/S
  ...

Pull networking fixes from David Miller:

 1) Various mptcp fixupes from Florian Westphal and Geery Uytterhoeven.

 2) Don't clear the node/port GUIDs after we've assigned the correct
    values to them. From Leon Romanovsky.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net:
  net/core: Do not clear VF index for node/port GUIDs query
  mptcp: Fix undefined mptcp_handle_ipv6_mapped for modular IPV6
  net: drop_monitor: Use kstrdup
  udp: document udp_rcv_segment special case for looped packets
  mptcp: MPTCP_HMAC_TEST should depend on MPTCP
  mptcp: Fix incorrect IPV6 dependency check
  Revert "MAINTAINERS: mptcp@ mailing list is moderated"
  mptcp: handle tcp fallback when using syn cookies
  mptcp: avoid a lockdep splat when mcast group was joined
  mptcp: fix panic on user pointer access
  mptcp: defer freeing of cached ext until last moment
  net: mvneta: fix XDP support if sw bm is used as fallback
  sch_choke: Use kvcalloc
  mptcp: Fix build with PROC_FS disabled.
  MAINTAINERS: mptcp@ mailing list is moderated

Pull IDE updates from David Miller:

 1) Fix mem region name in tx4949ide driver, from Christophe JAILLET.

 2) Make drive->dn read only, it should not be changeable by users. From
    Dan Carpenter.

 3) Several cast fixups from Krzysztof Kozlowski.

There is also going to be a removal of a now unused IDE driver, but that
will come via the MIPS tree.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/ide:
  ide: make drive->dn read only
  ide: serverworks: potential overflow in svwks_set_pio_mode()
  cmd64x: potential buffer overflow in cmd64x_program_timings()
  ide: remove unneeded header include path to drivers/ide
  ide: qd65xx: Fix cast to pointer from integer of different size
  ide: ht6560b: Fix cast to pointer from integer of different size
  ide: remove set but not used variable 'hwif'
  ide: remove unnecessary touch_softlockup_watchdog
  ide: tx4939ide: Fix the name used in a 'devm_request_mem_region()' call
  ide: Use dev_get_drvdata where possible

Pull sparc updates from David Miller:

 1) Add a proper .exit.data section.

 2) Fix ipc64_perm type definition, from Arnd Bergmann.

 3) Support folded p4d page tables on sparc64, from Mike Rapport.

 4) Remove uses of struct timex, also from Arnd Bergmann.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  y2038: sparc: remove use of struct timex
  sparc64: add support for folded p4d page tables
  sparc/console: kill off obsolete declarations
  sparc32: fix struct ipc64_perm type definition
  sparc32, leon: Stop adding vendor and device id to prom ambapp path components
  sparc: Add .exit.data section.
  sparc: remove unneeded uapi/asm/statfs.h

Pull arm64 KVM fix from Catalin Marinas:
 "Set the correct MDCR_EL2 register value on the first run of a vCPU"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  KVM: arm64: Write arch.mdcr_el2 changes since last vcpu_load on VHE

VF numbers were assigned to node_guid and port_guid, but cleared
right before such query calls were issued. It caused to return
node/port GUIDs of VF index 0 for all VFs.

Fixes: 30aad417 ("net/core: Add support for getting VF GUIDs")
Reported-by: Adrian Chiris <adrianc@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

'struct timex' is one of the last users of 'struct timeval' and is
only referenced in one place in the kernel any more, to convert the
user space timex into the kernel-internal version on sparc64, with a
different tv_usec member type.

As a preparation for hiding the time_t definition and everything
using that in the kernel, change the implementation once more
to only convert the timeval member, and then enclose the
struct definition in an #ifdef.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Implement primitives necessary for the 4th level folding, add walks of p4d
level where appropriate and replace 5level-fixup.h with pgtable-nop4d.h.
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

The IDE core always sets ->dn correctly so changing it is never
required.

Setting it to a different value than assigned by IDE core is very likely
to result in data corruption (due to wrong transfer timings being set on
the controller etc.)
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Tested-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

If CONFIG_MPTCP=y, CONFIG_MPTCP_IPV6=n, and CONFIG_IPV6=m:

    ERROR: "mptcp_handle_ipv6_mapped" [net/ipv6/ipv6.ko] undefined!

This does not happen if CONFIG_MPTCP_IPV6=y, as CONFIG_MPTCP_IPV6
selects CONFIG_IPV6, and thus forces CONFIG_IPV6 builtin.

As exporting a symbol for an empty function would be a bit wasteful, fix
this by providing a dummy version of mptcp_handle_ipv6_mapped() for the
CONFIG_MPTCP_IPV6=n case.

Rename mptcp_handle_ipv6_mapped() to mptcpv6_handle_mapped(), to make it
clear this is a pure-IPV6 function, just like mptcpv6_init().

Fixes: cec37a6e ("mptcp: Handle MP_CAPABLE options for outgoing connections")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Convert the equivalent but rather odd uses of kmemdup with
__GFP_ZERO to the more common kstrdup and avoid unnecessary
zeroing of copied over memory.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Commit 6cd021a5 ("udp: segment looped gso packets correctly")
fixes an issue with rare udp gso multicast packets looped onto the
receive path.

The stable backport makes the narrowest change to target only these
packets, when needed. As opposed to, say, expanding __udp_gso_segment,
which is harder to reason to be free from unintended side-effects.

But the resulting code is hardly self-describing.
Document its purpose and rationale.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

As the MPTCP HMAC test is integrated into the MPTCP code, it can be
built only when MPTCP is enabled.  Hence when MPTCP is disabled, asking
the user if the test code should be enabled is futile.

Wrap the whole block of MPTCP-specific config options inside a check for
MPTCP.  While at it, drop the "default n" for MPTCP_HMAC_TEST, as that
is the default anyway.

Fixes: 65492c5a ("mptcp: move from sha1 (v0) to sha256 (v1)")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

If CONFIG_MPTCP=y, CONFIG_MPTCP_IPV6=n, and CONFIG_IPV6=m:

    net/mptcp/protocol.o: In function `__mptcp_tcp_fallback':
    protocol.c:(.text+0x786): undefined reference to `inet6_stream_ops'

Fix this by checking for CONFIG_MPTCP_IPV6 instead of CONFIG_IPV6, like
is done in all other places in the mptcp code.

Fixes: 8ab183de ("mptcp: cope with later TCP fallback")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

A couple of OOPS fixes, fixes for TU1xx if firmware isn't available,
better behaviour in the face of GPU faults, and a patch to make HD
audio work again after runpm changes.
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Ben Skeggs <skeggsb@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ <CACAvsv4xcLF6Ahh7UYEesn-wBEksd2da+ghusBAdODMrH7Sz2A@mail.gmail.com

Pull mmu_notifier updates from Jason Gunthorpe:
 "This small series revises the names in mmu_notifier to make the code
  clearer and more readable"

* tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
  mm/mmu_notifiers: Use 'interval_sub' as the variable for mmu_interval_notifier
  mm/mmu_notifiers: Use 'subscription' as the variable name for mmu_notifier
  mm/mmu_notifier: Rename struct mmu_notifier_mm to mmu_notifier_subscriptions

Pull thread management updates from Christian Brauner:
 "Sargun Dhillon over the last cycle has worked on the pidfd_getfd()
  syscall.

  This syscall allows for the retrieval of file descriptors of a process
  based on its pidfd. A task needs to have ptrace_may_access()
  permissions with PTRACE_MODE_ATTACH_REALCREDS (suggested by Oleg and
  Andy) on the target.

  One of the main use-cases is in combination with seccomp's user
  notification feature. As a reminder, seccomp's user notification
  feature was made available in v5.0. It allows a task to retrieve a
  file descriptor for its seccomp filter. The file descriptor is usually
  handed of to a more privileged supervising process. The supervisor can
  then listen for syscall events caught by the seccomp filter of the
  supervisee and perform actions in lieu of the supervisee, usually
  emulating syscalls. pidfd_getfd() is needed to expand its uses.

  There are currently two major users that wait on pidfd_getfd() and one
  future user:

   - Netflix, Sargun said, is working on a service mesh where users
     should be able to connect to a dns-based VIP. When a user connects
     to e.g. 1.2.3.4:80 that runs e.g. service "foo" they will be
     redirected to an envoy process. This service mesh uses seccomp user
     notifications and pidfd to intercept all connect calls and instead
     of connecting them to 1.2.3.4:80 connects them to e.g.
     127.0.0.1:8080.

   - LXD uses the seccomp notifier heavily to intercept and emulate
     mknod() and mount() syscalls for unprivileged containers/processes.
     With pidfd_getfd() more uses-cases e.g. bridging socket connections
     will be possible.

   - The patchset has also seen some interest from the browser corner.
     Right now, Firefox is using a SECCOMP_RET_TRAP sandbox managed by a
     broker process. In the future glibc will start blocking all signals
     during dlopen() rendering this type of sandbox impossible. Hence,
     in the future Firefox will switch to a seccomp-user-nofication
     based sandbox which also makes use of file descriptor retrieval.
     The thread for this can be found at
     https://sourceware.org/ml/libc-alpha/2019-12/msg00079.html

  With pidfd_getfd() it is e.g. possible to bridge socket connections
  for the supervisee (binding to a privileged port) and taking actions
  on file descriptors on behalf of the supervisee in general.

  Sargun's first version was using an ioctl on pidfds but various people
  pushed for it to be a proper syscall which he duely implemented as
  well over various review cycles. Selftests are of course included.
  I've also added instructions how to deal with merge conflicts below.

  There's also a small fix coming from the kernel mentee project to
  correctly annotate struct sighand_struct with __rcu to fix various
  sparse warnings. We've received a few more such fixes and even though
  they are mostly trivial I've decided to postpone them until after -rc1
  since they came in rather late and I don't want to risk introducing
  build warnings.

  Finally, there's a new prctl() command PR_{G,S}ET_IO_FLUSHER which is
  needed to avoid allocation recursions triggerable by storage drivers
  that have userspace parts that run in the IO path (e.g. dm-multipath,
  iscsi, etc). These allocation recursions deadlock the device.

  The new prctl() allows such privileged userspace components to avoid
  allocation recursions by setting the PF_MEMALLOC_NOIO and
  PF_LESS_THROTTLE flags. The patch carries the necessary acks from the
  relevant maintainers and is routed here as part of prctl()
  thread-management."

* tag 'threads-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaim
  sched.h: Annotate sighand_struct with __rcu
  test: Add test for pidfd getfd
  arch: wire up pidfd_getfd syscall
  pid: Implement pidfd_getfd syscall
  vfs, fdtable: Add fget_task helper

Pull io_uring updates from Jens Axboe:

 - Support for various new opcodes (fallocate, openat, close, statx,
   fadvise, madvise, openat2, non-vectored read/write, send/recv, and
   epoll_ctl)

 - Faster ring quiesce for fileset updates

 - Optimizations for overflow condition checking

 - Support for max-sized clamping

 - Support for probing what opcodes are supported

 - Support for io-wq backend sharing between "sibling" rings

 - Support for registering personalities

 - Lots of little fixes and improvements

* tag 'for-5.6/io_uring-vfs-2020-01-29' of git://git.kernel.dk/linux-block: (64 commits)
  io_uring: add support for epoll_ctl(2)
  eventpoll: support non-blocking do_epoll_ctl() calls
  eventpoll: abstract out epoll_ctl() handler
  io_uring: fix linked command file table usage
  io_uring: support using a registered personality for commands
  io_uring: allow registering credentials
  io_uring: add io-wq workqueue sharing
  io-wq: allow grabbing existing io-wq
  io_uring/io-wq: don't use static creds/mm assignments
  io-wq: make the io_wq ref counted
  io_uring: fix refcounting with batched allocations at OOM
  io_uring: add comment for drain_next
  io_uring: don't attempt to copy iovec for READ/WRITE
  io_uring: honor IOSQE_ASYNC for linked reqs
  io_uring: prep req when do IOSQE_ASYNC
  io_uring: use labeled array init in io_op_defs
  io_uring: optimise sqe-to-req flags translation
  io_uring: remove REQ_F_IO_DRAINED
  io_uring: file switch work needs to get flushed on exit
  io_uring: hide uring_fd in ctx
  ...

Pull SCSI updates from James Bottomley:
 "This series is slightly unusual because it includes Arnd's compat
  ioctl tree here:

    1c46a2cf Merge tag 'block-ioctl-cleanup-5.6' into 5.6/scsi-queue

  Excluding Arnd's changes, this is mostly an update of the usual
  drivers: megaraid_sas, mpt3sas, qla2xxx, ufs, lpfc, hisi_sas.

  There are a couple of core and base updates around error propagation
  and atomicity in the attribute container base we use for the SCSI
  transport classes.

  The rest is minor changes and updates"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (149 commits)
  scsi: hisi_sas: Rename hisi_sas_cq.pci_irq_mask
  scsi: hisi_sas: Add prints for v3 hw interrupt converge and automatic affinity
  scsi: hisi_sas: Modify the file permissions of trigger_dump to write only
  scsi: hisi_sas: Replace magic number when handle channel interrupt
  scsi: hisi_sas: replace spin_lock_irqsave/spin_unlock_restore with spin_lock/spin_unlock
  scsi: hisi_sas: use threaded irq to process CQ interrupts
  scsi: ufs: Use UFS device indicated maximum LU number
  scsi: ufs: Add max_lu_supported in struct ufs_dev_info
  scsi: ufs: Delete is_init_prefetch from struct ufs_hba
  scsi: ufs: Inline two functions into their callers
  scsi: ufs: Move ufshcd_get_max_pwr_mode() to ufshcd_device_params_init()
  scsi: ufs: Split ufshcd_probe_hba() based on its called flow
  scsi: ufs: Delete struct ufs_dev_desc
  scsi: ufs: Fix ufshcd_probe_hba() reture value in case ufshcd_scsi_add_wlus() fails
  scsi: ufs-mediatek: enable low-power mode for hibern8 state
  scsi: ufs: export some functions for vendor usage
  scsi: ufs-mediatek: add dbg_register_dump implementation
  scsi: qla2xxx: Fix a NULL pointer dereference in an error path
  scsi: qla1280: Make checking for 64bit support consistent
  scsi: megaraid_sas: Update driver version to 07.713.01.00-rc1
  ...

Merge tag 'for-5.6/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - Fix DM core's potential for q->make_request_fn NULL pointer in the
   unlikely case that a DM device is created without a DM table and then
   accessed due to upper-layer userspace code or user error.

 - Fix DM thin-provisioning's metadata_pre_commit_callback to not use
   memory after it is free'd. Also refactor code to disallow changing
   the thin-pool's data device once in use -- doing so guarantees smae
   lifetime of pool's data device relative to the pool metadata.

 - Fix DM space maps used by DM thinp and DM cache to avoid reuse of a
   already used block. This race was identified with extremely heavy
   snapshot use in the context of DM thin provisioning.

 - Fix DM raid's table status relative to an active rebuild.

 - Fix DM crypt to use GFP_NOIO rather than GFP_NOFS in call to
   skcipher_request_alloc(). Also fix benbi IV constructor crash if used
   in authenticated mode.

 - Add DM crypt support for Elephant diffuser to allow for Bitlocker
   compatibility.

 - Fix DM verity target to not prefetch hash blocks for data that has
   already been verified.

 - Fix DM writecache's incorrect flush sequence during commit when in
   SSD mode.

 - Improve DM writecache's sequential write performance on SSDs.

 - Add DM zoned target support for zone sizes smaller than 128MiB.

 - Add DM multipath 'queue_if_no_path_timeout_secs' module param to
   allow timeout if path isn't reinstated. This allows users a kernel
   safety-net against IO hanging indefinitely, due to no active paths,
   that has historically only been provided by multipathd userspace.

 - Various DM code cleanups to use true/false rather than 1/0, a
   variable rename in dm-dust, and fix for a math error in comment for
   DM thin metadata's ondisk format.

* tag 'for-5.6/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (21 commits)
  dm: fix potential for q->make_request_fn NULL pointer
  dm writecache: improve performance of large linear writes on SSDs
  dm mpath: Add timeout mechanism for queue_if_no_path
  dm thin: change data device's flush_bio to be member of struct pool
  dm thin: don't allow changing data device during thin-pool reload
  dm thin: fix use-after-free in metadata_pre_commit_callback
  dm thin metadata: use pool locking at end of dm_pool_metadata_close
  dm writecache: fix incorrect flush sequence when doing SSD mode commit
  dm crypt: fix benbi IV constructor crash if used in authenticated mode
  dm crypt: Implement Elephant diffuser for Bitlocker compatibility
  dm space map common: fix to ensure new block isn't already in use
  dm verity: don't prefetch hash blocks for already-verified data
  dm crypt: fix GFP flags passed to skcipher_request_alloc()
  dm thin metadata: Fix trivial math error in on-disk format documentation
  dm thin metadata: use true/false for bool variable
  dm snapshot: use true/false for bool variable
  dm bio prison v2: use true/false for bool variable
  dm mpath: use true/false for bool variable
  dm zoned: support zone sizes smaller than 128MiB
  dm raid: table line rebuild status fixes
  ...

Pull documentation updates from Jonathan Corbet:
 "It has been a relatively quiet cycle for documentation, but there's
  still a couple of things of note:

   - Conversion of the NFS documentation to RST

   - A new document on how to help with documentation (and a maintainer
     profile entry too)

  Plus the usual collection of typo fixes, etc"

* tag 'docs-5.6' of git://git.lwn.net/linux: (40 commits)
  docs: filesystems: add overlayfs to index.rst
  docs: usb: remove some broken references
  scripts/find-unused-docs: Fix massive false positives
  docs: nvdimm: use ReST notation for subsection
  zram: correct documentation about sysfs node of huge page writeback
  Documentation: zram: various fixes in zram.rst
  Add a maintainer entry profile for documentation
  Add a document on how to contribute to the documentation
  docs: Keep up with the location of NoUri
  Documentation: Call out example SYM_FUNC_* usage as x86-specific
  Documentation: nfs: fault_injection: convert to ReST
  Documentation: nfs: pnfs-scsi-server: convert to ReST
  Documentation: nfs: convert pnfs-block-server to ReST
  Documentation: nfs: idmapper: convert to ReST
  Documentation: convert nfsd-admin-interfaces to ReST
  Documentation: nfs-rdma: convert to ReST
  Documentation: nfsroot.rst: COSMETIC: refill a paragraph
  Documentation: nfsroot.txt: convert to ReST
  Documentation: convert nfs.txt to ReST
  Documentation: filesystems: convert vfat.txt to RST
  ...

Merge tag 'linux-kselftest-5.6-rc1-kunit' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull Kselftest kunit updates from Shuah Khan:
 "This kunit update consists of:

   - Support for building kunit as a module from Alan Maguire

   - AppArmor KUnit tests for policy unpack from Mike Salvatore"

* tag 'linux-kselftest-5.6-rc1-kunit' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  kunit: building kunit as a module breaks allmodconfig
  kunit: update documentation to describe module-based build
  kunit: allow kunit to be loaded as a module
  kunit: remove timeout dependence on sysctl_hung_task_timeout_seconds
  kunit: allow kunit tests to be loaded as a module
  kunit: hide unexported try-catch interface in try-catch-impl.h
  kunit: move string-stream.h to lib/kunit
  apparmor: add AppArmor KUnit tests for policy unpack

Merge tag 'linux-kselftest-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull Kselftest update from Shuah Khan:
 "This Kselftest update consists of several fixes to framework and
  individual tests.

  In addition, it enables LKDTM tests adding lkdtm target to kselftest
  Makefile"

* tag 'linux-kselftest-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  selftests/ftrace: fix glob selftest
  selftests: settings: tests can be in subsubdirs
  kselftest: Minimise dependency of get_size on C library interfaces
  selftests/livepatch: Remove unused local variable in set_ftrace_enabled()
  selftests/livepatch: Replace set_dynamic_debug() with setup_config() in README
  selftests/lkdtm: Add tests for LKDTM targets
  selftests: Uninitialized variable in test_cgcore_proc_migration()
  selftests: fix build behaviour on targets' failures

Merge tag 'y2038-drivers-for-v5.6-signed' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground

Pull y2038 updates from Arnd Bergmann:
 "Core, driver and file system changes

  These are updates to device drivers and file systems that for some
  reason or another were not included in the kernel in the previous
  y2038 series.

  I've gone through all users of time_t again to make sure the kernel is
  in a long-term maintainable state, replacing all remaining references
  to time_t with safe alternatives.

  Some related parts of the series were picked up into the nfsd, xfs,
  alsa and v4l2 trees. A final set of patches in linux-mm removes the
  now unused time_t/timeval/timespec types and helper functions after
  all five branches are merged for linux-5.6, ensuring that no new users
  get merged.

  As a result, linux-5.6, or my backport of the patches to 5.4 [1],
  should be the first release that can serve as a base for a 32-bit
  system designed to run beyond year 2038, with a few remaining caveats:

   - All user space must be compiled with a 64-bit time_t, which will be
     supported in the coming musl-1.2 and glibc-2.32 releases, along
     with installed kernel headers from linux-5.6 or higher.

   - Applications that use the system call interfaces directly need to
     be ported to use the time64 syscalls added in linux-5.1 in place of
     the existing system calls. This impacts most users of futex() and
     seccomp() as well as programming languages that have their own
     runtime environment not based on libc.

   - Applications that use a private copy of kernel uapi header files or
     their contents may need to update to the linux-5.6 version, in
     particular for sound/asound.h, xfs/xfs_fs.h, linux/input.h,
     linux/elfcore.h, linux/sockios.h, linux/timex.h and
     linux/can/bcm.h.

   - A few remaining interfaces cannot be changed to pass a 64-bit
     time_t in a compatible way, so they must be configured to use
     CLOCK_MONOTONIC times or (with a y2106 problem) unsigned 32-bit
     timestamps. Most importantly this impacts all users of 'struct
     input_event'.

   - All y2038 problems that are present on 64-bit machines also apply
     to 32-bit machines. In particular this affects file systems with
     on-disk timestamps using signed 32-bit seconds: ext4 with
     ext3-style small inodes, ext2, xfs (to be fixed soon) and ufs"

[1] https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/log/?h=y2038-endgame

* tag 'y2038-drivers-for-v5.6-signed' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (21 commits)
  Revert "drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC"
  y2038: sh: remove timeval/timespec usage from headers
  y2038: sparc: remove use of struct timex
  y2038: rename itimerval to __kernel_old_itimerval
  y2038: remove obsolete jiffies conversion functions
  nfs: fscache: use timespec64 in inode auxdata
  nfs: fix timstamp debug prints
  nfs: use time64_t internally
  sunrpc: convert to time64_t for expiry
  drm/etnaviv: avoid deprecated timespec
  drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC
  drm/msm: avoid using 'timespec'
  hfs/hfsplus: use 64-bit inode timestamps
  hostfs: pass 64-bit timestamps to/from user space
  packet: clarify timestamp overflow
  tsacct: add 64-bit btime field
  acct: stop using get_seconds()
  um: ubd: use 64-bit time_t where possible
  xtensa: ISS: avoid struct timeval
  dlm: use SO_SNDTIMEO_NEW instead of SO_SNDTIMEO_OLD
  ...

Pull printk update from Petr Mladek:
 "Prevent replaying log on all consoles"

* tag 'printk-for-5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
  printk: fix exclusive_console replaying

This adds IORING_OP_EPOLL_CTL, which can perform the same work as the
epoll_ctl(2) system call.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Also make it available outside of epoll, along with the helper that
decides if we need to copy the passed in epoll_event.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

No functional changes in this patch.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We're not consistent in how the file table is grabbed and assigned if we
have a command linked that requires the use of it.

Add ->file_table to the io_op_defs[] array, and use that to determine
when to grab the table instead of having the handlers set it if they
need to defer. This also means we can kill the IO_WQ_WORK_NEEDS_FILES
flag. We always initialize work->files, so io-wq can just check for
that.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull erofs updates from Gao Xiang:
 "A regression fix, several cleanups and (maybe) plus an upcoming new
  mount api convert patch as a part of vfs update are considered
  available for this cycle.

  All commits have been in linux-next and tested with no smoke out.

  Summary:

   - fix an out-of-bound read access introduced in v5.3, which could
     rarely cause data corruption

   - various cleanup patches"

* tag 'erofs-for-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: clean up z_erofs_submit_queue()
  erofs: fold in postsubmit_is_all_bypassed()
  erofs: fix out-of-bound read for shifted uncompressed block
  erofs: remove void tagging/untagging of workgroup pointers
  erofs: remove unused tag argument while registering a workgroup
  erofs: remove unused tag argument while finding a workgroup
  erofs: correct indentation of an assigned structure inside a function

Pull adfs updates from Al Viro:
 "adfs stuff for this cycle"

* 'work.adfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (42 commits)
  fs/adfs: bigdir: Fix an error code in adfs_fplus_read()
  Documentation: update adfs filesystem documentation
  fs/adfs: mostly divorse inode number from indirect disc address
  fs/adfs: super: add support for E and E+ floppy image formats
  fs/adfs: super: extract filesystem block probe
  fs/adfs: dir: remove debug in adfs_dir_update()
  fs/adfs: super: fix inode dropping
  fs/adfs: bigdir: implement directory update support
  fs/adfs: bigdir: calculate and validate directory checkbyte
  fs/adfs: bigdir: directory validation strengthening
  fs/adfs: bigdir: extract directory validation
  fs/adfs: bigdir: factor out directory entry offset calculation
  fs/adfs: newdir: split out directory commit from update
  fs/adfs: newdir: clean up adfs_f_update()
  fs/adfs: newdir: merge adfs_dir_read() into adfs_f_read()
  fs/adfs: newdir: improve directory validation
  fs/adfs: newdir: factor out directory format validation
  fs/adfs: dir: use pointers to access directory head/tails
  fs/adfs: dir: add more efficient iterate() per-format method
  fs/adfs: dir: switch to iterate_shared method
  ...

This reverts commit 74759e16.

mptcp@lists.01.org accepts messages from non-subscribers. There was an
invisible and unexpected server-wide rule limiting the number of
recipients for subscribers and non-subscribers alike, and that has now
been turned off for this list.

Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull openat2 support from Al Viro:
 "This is the openat2() series from Aleksa Sarai.

  I'm afraid that the rest of namei stuff will have to wait - it got
  zero review the last time I'd posted #work.namei, and there had been a
  leak in the posted series I'd caught only last weekend. I was going to
  repost it on Monday, but the window opened and the odds of getting any
  review during that... Oh, well.

  Anyway, openat2 part should be ready; that _did_ get sane amount of
  review and public testing, so here it comes"

From Aleksa's description of the series:
 "For a very long time, extending openat(2) with new features has been
  incredibly frustrating. This stems from the fact that openat(2) is
  possibly the most famous counter-example to the mantra "don't silently
  accept garbage from userspace" -- it doesn't check whether unknown
  flags are present[1].

  This means that (generally) the addition of new flags to openat(2) has
  been fraught with backwards-compatibility issues (O_TMPFILE has to be
  defined as __O_TMPFILE|O_DIRECTORY|[O_RDWR or O_WRONLY] to ensure old
  kernels gave errors, since it's insecure to silently ignore the
  flag[2]). All new security-related flags therefore have a tough road
  to being added to openat(2).

  Furthermore, the need for some sort of control over VFS's path
  resolution (to avoid malicious paths resulting in inadvertent
  breakouts) has been a very long-standing desire of many userspace
  applications.

  This patchset is a revival of Al Viro's old AT_NO_JUMPS[3] patchset
  (which was a variant of David Drysdale's O_BENEATH patchset[4] which
  was a spin-off of the Capsicum project[5]) with a few additions and
  changes made based on the previous discussion within [6] as well as
  others I felt were useful.

  In line with the conclusions of the original discussion of
  AT_NO_JUMPS, the flag has been split up into separate flags. However,
  instead of being an openat(2) flag it is provided through a new
  syscall openat2(2) which provides several other improvements to the
  openat(2) interface (see the patch description for more details). The
  following new LOOKUP_* flags are added:

  LOOKUP_NO_XDEV:

     Blocks all mountpoint crossings (upwards, downwards, or through
     absolute links). Absolute pathnames alone in openat(2) do not
     trigger this. Magic-link traversal which implies a vfsmount jump is
     also blocked (though magic-link jumps on the same vfsmount are
     permitted).

  LOOKUP_NO_MAGICLINKS:

     Blocks resolution through /proc/$pid/fd-style links. This is done
     by blocking the usage of nd_jump_link() during resolution in a
     filesystem. The term "magic-links" is used to match with the only
     reference to these links in Documentation/, but I'm happy to change
     the name.

     It should be noted that this is different to the scope of
     ~LOOKUP_FOLLOW in that it applies to all path components. However,
     you can do openat2(NO_FOLLOW|NO_MAGICLINKS) on a magic-link and it
     will *not* fail (assuming that no parent component was a
     magic-link), and you will have an fd for the magic-link.

     In order to correctly detect magic-links, the introduction of a new
     LOOKUP_MAGICLINK_JUMPED state flag was required.

  LOOKUP_BENEATH:

     Disallows escapes to outside the starting dirfd's
     tree, using techniques such as ".." or absolute links. Absolute
     paths in openat(2) are also disallowed.

     Conceptually this flag is to ensure you "stay below" a certain
     point in the filesystem tree -- but this requires some additional
     to protect against various races that would allow escape using
     "..".

     Currently LOOKUP_BENEATH implies LOOKUP_NO_MAGICLINKS, because it
     can trivially beam you around the filesystem (breaking the
     protection). In future, there might be similar safety checks done
     as in LOOKUP_IN_ROOT, but that requires more discussion.

  In addition, two new flags are added that expand on the above ideas:

  LOOKUP_NO_SYMLINKS:

     Does what it says on the tin. No symlink resolution is allowed at
     all, including magic-links. Just as with LOOKUP_NO_MAGICLINKS this
     can still be used with NOFOLLOW to open an fd for the symlink as
     long as no parent path had a symlink component.

  LOOKUP_IN_ROOT:

     This is an extension of LOOKUP_BENEATH that, rather than blocking
     attempts to move past the root, forces all such movements to be
     scoped to the starting point. This provides chroot(2)-like
     protection but without the cost of a chroot(2) for each filesystem
     operation, as well as being safe against race attacks that
     chroot(2) is not.

     If a race is detected (as with LOOKUP_BENEATH) then an error is
     generated, and similar to LOOKUP_BENEATH it is not permitted to
     cross magic-links with LOOKUP_IN_ROOT.

     The primary need for this is from container runtimes, which
     currently need to do symlink scoping in userspace[7] when opening
     paths in a potentially malicious container.

     There is a long list of CVEs that could have bene mitigated by
     having RESOLVE_THIS_ROOT (such as CVE-2017-1002101,
     CVE-2017-1002102, CVE-2018-15664, and CVE-2019-5736, just to name a
     few).

  In order to make all of the above more usable, I'm working on
  libpathrs[8] which is a C-friendly library for safe path resolution.
  It features a userspace-emulated backend if the kernel doesn't support
  openat2(2). Hopefully we can get userspace to switch to using it, and
  thus get openat2(2) support for free once it's ready.

  Future work would include implementing things like
  RESOLVE_NO_AUTOMOUNT and possibly a RESOLVE_NO_REMOTE (to allow
  programs to be sure they don't hit DoSes though stale NFS handles)"

* 'work.openat2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  Documentation: path-lookup: include new LOOKUP flags
  selftests: add openat2(2) selftests
  open: introduce openat2(2) syscall
  namei: LOOKUP_{IN_ROOT,BENEATH}: permit limited ".." resolution
  namei: LOOKUP_IN_ROOT: chroot-like scoped resolution
  namei: LOOKUP_BENEATH: O_BENEATH-like scoped resolution
  namei: LOOKUP_NO_XDEV: block mountpoint crossing
  namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution
  namei: LOOKUP_NO_SYMLINKS: block symlink resolution
  namei: allow set_root() to produce errors
  namei: allow nd_jump_link() to produce errors
  nsfs: clean-up ns_get_path() signature to return int
  namei: only return -ECHILD from follow_dotdot_rcu()