If writeback_cache is enabled, then the size, mtime and ctime attributes of
regular files are always valid in the kernel's cache.  They are retrieved
from userspace only when the inode is freshly looked up.

Add a more generic "cache_mask", that indicates which attributes are
currently valid in cache.

This patch doesn't change behavior.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

In case of writeback_cache fuse_fillattr() would revert the queried
attributes to the cached version.

Move this to fuse_change_attributes() in order to manage the writeback
logic in a central helper.  This will be necessary for patches that follow.

Only fuse_do_getattr() -> fuse_fillattr() uses the attributes after calling
fuse_change_attributes(), so this should not change behavior.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

There are two instances of "bool is_wb = fc->writeback_cache" where the
actual use mostly involves checking "is_wb && S_ISREG(inode->i_mode)".

Clean up these cases by storing the second condition in the local variable.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

It's safe to call file_update_time() if writeback cache is not enabled,
since S_NOCMTIME is set in this case.  This part is purely a cleanup.

__fuse_copy_file_range() also calls fuse_write_update_attr() only in the
writeback cache case.  This is inconsistent with other callers, where it's
called unconditionally.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

A READ request returning a short count is taken as indication of EOF, and
the cached file size is modified accordingly.

Fix the attribute version checking to allow for changes to fc->attr_version
on other inodes.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Extend the fuse_write_update_attr() helper to invalidate cached attributes
after a write.

This has already been done in all cases except in fuse_notify_store(), so
this is mostly a cleanup.

fuse_direct_write_iter() calls fuse_direct_IO() which already calls
fuse_write_update_attr(), so don't repeat that again in the former.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

This function already updates the attr_version in fuse_inode, regardless of
whether the size was changed or not.

Rename the helper to fuse_write_update_attr() to reflect the more generic
nature.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

The attribute version in fuse_inode should be updated whenever the
attributes might have changed on the server.  In case of cached writes this
is not the case, so updating the attr_version is unnecessary and could
possibly affect performance.

Open code the remaining part of fuse_write_update_size().
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Only invalidate attributes that the operation might have changed.

Introduce two constants for common combinations of changed attributes:

  FUSE_STATX_MODIFY: file contents are modified but not size

  FUSE_STATX_MODSIZE: size and/or file contents modified
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

The fuse_iget() call in create_new_entry() already updated the inode with
all the new attributes and incremented the attribute version.

Incrementing the nlink will result in the wrong count.  This wasn't noticed
because the attributes were invalidated right after this.

Updating ctime is still needed for the writeback case when the ctime is not
refreshed.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Rename didn't decrement/clear nlink on overwritten target inode.

Create a common helper fuse_entry_unlinked() that handles this for unlink,
rmdir and rename.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Use list_first_entry_or_null() instead of list_empty() + list_entry().
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Logically it belongs there since attributes are invalidated due to the
updated ctime.  This is a cleanup and should not change behavior.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

'ia->io=io' has been set in fuse_io_alloc.
Signed-off-by: Peng Hao <flyingpeng@tencent.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Due to the introduction of kmap_local_*, the storage of slots used for
short-term mapping has changed from per-CPU to per-thread.  kmap_atomic()
disable preemption, while kmap_local_*() only disable migration.

There is no need to disable preemption in several kamp_atomic places used
in fuse.

Link: https://lwn.net/Articles/836144/Signed-off-by: Peng Hao <flyingpeng@tencent.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Add missing inode lock annotatation; found by syzbot.

Reported-and-tested-by: syzbot+9f747458f5990eaa8d43@syzkaller.appspotmail.com
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Fuse ->release() is otherwise asynchronous for the reason that it can
happen in contexts unrelated to close/munmap.

Inode is already written back from fuse_flush().  Add it to
fuse_vma_close() as well to make sure inode dirtying from mmaps also get
written out before the file is released.

Also add error handling.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

In writeback cache mode mtime/ctime updates are cached, and flushed to the
server using the ->write_inode() callback.

Closing the file will result in a dirty inode being immediately written,
but in other cases the inode can remain dirty after all references are
dropped.  This result in the inode being written back from reclaim, which
can deadlock on a regular allocation while the request is being served.

The usual mechanisms (GFP_NOFS/PF_MEMALLOC*) don't work for FUSE, because
serving a request involves unrelated userspace process(es).

Instead do the same as for dirty pages: make sure the inode is written
before the last reference is gone.

 - fallocate(2)/copy_file_range(2): these call file_update_time() or
   file_modified(), so flush the inode before returning from the call

 - unlink(2), link(2) and rename(2): these call fuse_update_ctime(), so
   flush the ctime directly from this helper
Reported-by: chenguanyou <chenguanyou@xiaomi.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Instead of "goto err", return error directly, since there's no error
cleanup to do now.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Syzkaller reports a null pointer dereference in fuse_test_super() that is
caused by sb->s_fs_info being NULL.

This is due to the fact that fuse_fill_super() is initializing s_fs_info,
which is too late, it's already on the fs_supers list.  The initialization
needs to be done in sget_fc() with the sb_lock held.

Move allocation of fuse_mount and fuse_conn from fuse_fill_super() into
fuse_get_tree().

After this ->kill_sb() will always be called with non-NULL ->s_fs_info,
hence fuse_mount_destroy() can drop the test for non-NULL "fm".

Reported-by: syzbot+74a15f02ccb51f398601@syzkaller.appspotmail.com
Fixes: 5d5b74aa ("fuse: allow sharing existing sb")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1. call fuse_mount_destroy() for open coded variants

2. before deactivate_locked_super() don't need fuse_mount destruction since
that will now be done (if ->s_fs_info is not cleared)

3. rearrange fuse_mount setup in fuse_get_tree_submount() so that the
regular pattern can be used
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

The ->put_super callback is called from generic_shutdown_super() in case of
a fully initialized sb.  This is called from kill_***_super(), which is
called from ->kill_sb instances.

Fuse uses ->put_super to destroy the fs specific fuse_mount and drop the
reference to the fuse_conn, while it does the same on each error case
during sb setup.

This patch moves the destruction from fuse_put_super() to
fuse_mount_destroy(), called at the end of all ->kill_sb instances.  A
follup patch will clean up the error paths.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Checking "fm" works because currently sb->s_fs_info is cleared on error
paths; however, sb->s_root is what generic_shutdown_super() checks to
determine whether the sb was fully initialized or not.

This change will allow cleanup of sb setup error paths.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Pull libata fixes from Damien Le Moal:
 "Two fixes for this cycle:

   - Fix a null pointer dereference in ahci-platform driver (from Hai)

   - Fix uninitialized variables in pata_legacy driver (from Dan)"

* tag 'libata-5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata:
  ata: ahci_platform: fix null-ptr-deref in ahci_platform_enable_regulators()
  pata_legacy: fix a couple uninitialized variable bugs

Pull block fixes from Jens Axboe:
 "Bigger than usual for this point in time, the majority is fixing some
  issues around BDI lifetimes with the move from the request_queue to
  the disk in this release. In detail:

   - Series on draining fs IO for del_gendisk() (Christoph)

   - NVMe pull request via Christoph:
        - fix the abort command id (Keith Busch)
        - nvme: fix per-namespace chardev deletion (Adam Manzanares)

   - brd locking scope fix (Tetsuo)

   - BFQ fix (Paolo)"

* tag 'block-5.15-2021-10-17' of git://git.kernel.dk/linux-block:
  block, bfq: reset last_bfqq_created on group change
  block: warn when putting the final reference on a registered disk
  brd: reduce the brd_devices_mutex scope
  kyber: avoid q->disk dereferences in trace points
  block: keep q_usage_counter in atomic mode after del_gendisk
  block: drain file system I/O on del_gendisk
  block: split bio_queue_enter from blk_queue_enter
  block: factor out a blk_try_enter_queue helper
  block: call submit_bio_checks under q_usage_counter
  nvme: fix per-namespace chardev deletion
  block/rnbd-clt-sysfs: fix a couple uninitialized variable bugs
  nvme-pci: Fix abort command id

Pull io_uring fix from Jens Axboe:
 "Just a single fix for a wrong condition for grabbing a lock, a
  regression in this merge window"

* tag 'io_uring-5.15-2021-10-17' of git://git.kernel.dk/linux-block:
  io_uring: fix wrong condition to grab uring lock

Pull virtio fixes from Michael Tsirkin:
 "Fixes up some issues in rc5"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  vhost-vdpa: Fix the wrong input in config_cb
  VDUSE: fix documentation underline warning
  Revert "virtio-blk: Add validation for block size in config space"
  vhost_vdpa: unset vq irq before freeing irq
  virtio: write back F_VERSION_1 before validate

Pull powerpc fixes from Michael Ellerman:

 - Fix a bug where guests on P9 with interrupts passed through could get
   stuck in synchronize_irq().

 - Fix a bug in KVM on P8 where secondary threads entering a guest would
   write outside their allocated stack.

 - Fix a bug in KVM on P8 where secondary threads could confuse the host
   offline code and cause the guest or host to crash.

Thanks to Cédric Le Goater.

* tag 'powerpc-5.15-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  KVM: PPC: Book3S HV: Make idle_kvm_start_guest() return 0 if it went to guest
  KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()
  powerpc/xive: Discard disabled interrupts in get_irqchip_state()

Pull objtool fixes from Borislav Petkov:

 - Update section headers before the respective relocations to not
   trigger a safety check in elftoolchain's implementation of libelf

 - Do not add garbage data to the .rela.orc_unwind_ip section

* tag 'objtool_urgent_for_v5.15_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Update section header before relocations
  objtool: Check for gelf_update_rel[a] failures

Pull EDAC fix from Borislav Petkov:

 - Log the "correct" uncorrectable error count in the armada_xp driver

* tag 'edac_urgent_for_v5.15_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras:
  EDAC/armada-xp: Fix output of uncorrectable error counter

Pull perf fix from Borislav Petkov:

 - Add Sapphire Rapids to the list of CPUs supporting the SMI count MSR

* tag 'perf_urgent_for_v5.15_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/msr: Add Sapphire Rapids CPU support

Pull EFI fixes from Borislav Petkov:
 "Forwarded from Ard Biesheuvel through the tip tree. Ard will send
  stuff directly in the near future.

  Low priority fixes but fixes nonetheless:

   - update stub diagnostic print that is no longer accurate

   - avoid statically allocated buffer for CPER error record decoding

   - avoid sleeping on the efi_runtime semaphore when calling the
     ResetSystem EFI runtime service"

* tag 'efi-urgent-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi: Change down_interruptible() in virt_efi_reset_system() to down_trylock()
  efi/cper: use stack buffer for error record decoding
  efi/libstub: Simplify "Exiting bootservices" message

Pull x86 fixes from Borislav Petkov:

 - Do not enable AMD memory encryption in Kconfig by default due to
   shortcomings of some platforms, leading to boot failures.

 - Mask out invalid bits in the MXCSR for 32-bit kernels again because
   Thomas and I don't know how to mask out bits properly. Third time's
   the charm.

* tag 'x86_urgent_for_v5.15_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu: Mask out the invalid MXCSR bits properly
  x86/Kconfig: Do not enable AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT automatically

Merge tag 'driver-core-5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fixes from Greg KH:
 "Here are some small driver core fixes for 5.15-rc6, all of which have
  been in linux-next for a while with no reported issues.

  They include:

   - kernfs negative dentry bugfix

   - simple pm bus fixes to resolve reported issues"

* tag 'driver-core-5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  drivers: bus: Delete CONFIG_SIMPLE_PM_BUS
  drivers: bus: simple-pm-bus: Add support for probing simple bus only devices
  driver core: Reject pointless SYNC_STATE_ONLY device links
  kernfs: don't create a negative dentry if inactive node exists

Pull char/misc driver fixes from Greg KH:
 "Here are some small char/misc driver fixes for 5.15-rc6 for reported
  issues that include:

   - habanalabs driver fixes

   - mei driver fixes and new ids

   - fpga new device ids

   - MAINTAINER file updates for fpga subsystem

   - spi module id table additions and fixes

   - fastrpc locking fixes

   - nvmem driver fix

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'char-misc-5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  eeprom: 93xx46: fix MODULE_DEVICE_TABLE
  nvmem: Fix shift-out-of-bound (UBSAN) with byte size cells
  mei: hbm: drop hbm responses on early shutdown
  mei: me: add Ice Lake-N device id.
  eeprom: 93xx46: Add SPI device ID table
  eeprom: at25: Add SPI ID table
  misc: HI6421V600_IRQ should depend on HAS_IOMEM
  misc: fastrpc: Add missing lock before accessing find_vma()
  cb710: avoid NULL pointer subtraction
  misc: gehc: Add SPI ID table
  MAINTAINERS: Drop outdated FPGA Manager website
  MAINTAINERS: Add Hao and Yilun as maintainers
  habanalabs: fix resetting args in wait for CS IOCTL
  fpga: ice40-spi: Add SPI device ID table

Pull staging and IIO driver fixes from Greg KH:
 "Here are a number of small IIO and staging driver fixes for 5.15-rc6.

  They include:

   - vc04_services bugfix for reported problem

   - r8188eu array underflow fix

   - iio driver fixes for a lot of tiny reported issues.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'staging-5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: r8188eu: prevent array underflow in rtw_hal_update_ra_mask()
  staging: vc04_services: shut up out-of-range warning
  iio: light: opt3001: Fixed timeout error when 0 lux
  iio: adis16480: fix devices that do not support sleep mode
  iio: mtk-auxadc: fix case IIO_CHAN_INFO_PROCESSED
  iio: adis16475: fix deadlock on frequency set
  iio: ssp_sensors: add more range checking in ssp_parse_dataframe()
  iio: ssp_sensors: fix error code in ssp_print_mcu_debug()
  iio: adc: ad7793: Fix IRQ flag
  iio: adc: ad7780: Fix IRQ flag
  iio: adc: ad7192: Add IRQ flag
  iio: adc: aspeed: set driver data when adc probe.
  iio: adc: rzg2l_adc: add missing clk_disable_unprepare() in rzg2l_adc_pm_runtime_resume()
  iio: adc: max1027: Fix the number of max1X31 channels
  iio: adc: max1027: Fix wrong shift with 12-bit devices
  iio: adc128s052: Fix the error handling path of 'adc128_probe()'
  iio: adc: rzg2l_adc: Fix -EBUSY timeout error return
  iio: accel: fxls8962af: return IRQ_HANDLED when fifo is flushed
  iio: dac: ti-dac5571: fix an error code in probe()

Pull serial driver fix from Greg KH:
 "Here is a single 8250 Kconfig fix for 5.15-rc6 that resolves a
  regression that showed up in 5.15-rc1. It has been in linux-next for a
  while with no reported issues"

* tag 'tty-5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: 8250: allow disabling of Freescale 16550 compile test

Pull USB fixes from Greg KH:
 "Here are some small USB fixes that resolve a number of tiny issues.
  They include:

   - new USB serial driver ids

   - xhci driver fixes for a bunch of issues

   - musb error path fixes.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'usb-5.15-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: musb: dsps: Fix the probe error path
  xhci: Enable trust tx length quirk for Fresco FL11 USB controller
  xhci: Fix command ring pointer corruption while aborting a command
  USB: xhci: dbc: fix tty registration race
  xhci: add quirk for host controllers that don't update endpoint DCS
  xhci: guard accesses to ep_state in xhci_endpoint_reset()
  USB: serial: qcserial: add EM9191 QDL support
  USB: serial: option: add Quectel EC200S-CN module support
  USB: serial: option: add prod. id for Quectel EG91
  USB: serial: option: add Telit LE910Cx composition 0x1204

Pull input fixes from Dmitry Torokhov:

 - a new product ID for the xpad joystick driver

 - fixes to resistive-adc-touch and snvs_pwrkey drivers

 - a change to touchscreen helpers to make clang happier

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: touchscreen - avoid bitwise vs logical OR warning
  Input: xpad - add support for another USB ID of Nacon GC-100
  Input: resistive-adc-touch - fix division by zero error on z1 == 0
  Input: snvs_pwrkey - add clk handling