linux-toradex.git/fs/fuse, branch master Linux kernel for Apalis and Colibri modules fuse: fix link error with CONFIG_FUSE_PASSTHROUGH=n 2026-10-31T00:22:37+00:00 Sasha Levin sashal@kernel.org 2026-10-26T15:26:50+00:00 1ea806165ec5fb8bca5d9990392fdb4f53a97977 Commit 2f19d54c055d ("fuse: support 64 bit, server allocated backing ID") moved the CONFIG_FUSE_PASSTHROUGH check out of the backing ioctl handlers and into fuse_get_conn_for_passthrough(). The calls from the handlers into backing.c, which is only built with CONFIG_FUSE_PASSTHROUGH, are now only removed if the compiler inlines that helper. It does not have to, and with gcc 11 and CONFIG_CC_OPTIMIZE_FOR_SIZE it doesn't: dev.c:(.text+0x355c): undefined reference to `fuse_backing_open' nios2-linux-ld: dev.c:(.text+0x3594): undefined reference to `fuse_backing_open_64' nios2-linux-ld: dev.c:(.text+0x35d0): undefined reference to `fuse_backing_close' Check CONFIG_FUSE_PASSTHROUGH in each handler again, as fuse_notify_backing_remove() does. The check still comes after the fuse_get_dev() and -ENOTCONN checks, so the errors userspace sees do not change. Fixes: 2f19d54c055d ("fuse: support 64 bit, server allocated backing ID") Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202610171310.uqRzJkIx-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202610260719.sj08mXBr-lkp@intel.com/ Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Commit 2f19d54c055d ("fuse: support 64 bit, server allocated backing ID")
moved the CONFIG_FUSE_PASSTHROUGH check out of the backing ioctl handlers
and into fuse_get_conn_for_passthrough(). The calls from the handlers
into backing.c, which is only built with CONFIG_FUSE_PASSTHROUGH, are now
only removed if the compiler inlines that helper. It does not have to,
and with gcc 11 and CONFIG_CC_OPTIMIZE_FOR_SIZE it doesn't:

  dev.c:(.text+0x355c): undefined reference to `fuse_backing_open'
  nios2-linux-ld: dev.c:(.text+0x3594): undefined reference to `fuse_backing_open_64'
  nios2-linux-ld: dev.c:(.text+0x35d0): undefined reference to `fuse_backing_close'

Check CONFIG_FUSE_PASSTHROUGH in each handler again, as
fuse_notify_backing_remove() does. The check still comes after the
fuse_get_dev() and -ENOTCONN checks, so the errors userspace sees do not
change.

Fixes: 2f19d54c055d ("fuse: support 64 bit, server allocated backing ID")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202610171310.uqRzJkIx-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202610260719.sj08mXBr-lkp@intel.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge tag 'mm-stable-2026-10-25-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2026-10-27T22:23:17+00:00 Linus Torvalds torvalds@linux-foundation.org 2026-10-27T22:23:17+00:00 8a36f53fd5ec3eff01f1b637d42cbdc3821d0493 Pull more MM updates from Andrew Morton: - "mm: make VMA flag semantics explicit, eliminate VM_SPECIAL" (Lorenzo Stoakes): Replace VM_SPECIAL with helpers describing mapping ownership and behavior. Enforce the mmap flag rules and convert affected drivers, removing ambiguous tests shared by driver mappings and ordinary memory. - "support kselftest on nommu platform" (Hajime Tazaki): Add opt-in mmap and mremap tests for NOMMU systems. Teach the runner to avoid its fork-dependent timeout command and document the build and runtime requirements. - "mm/collapse: separate a collapse from its callers" (Kiryl Shutsemau): Separate huge-page collapse from caller policy. Replace khugepaged identity checks with explicit permissions, and separate scanning from collapse with the mmap_lock drop in one place. - "mm: implement and use vma_has_anon_rmap(), silence KCSAN" (Lorenzo Stoakes): Provide a common helper for testing whether a VMA has anonymous reverse mappings. Document the locking rules, annotate intentional concurrent reads for KCSAN, and convert the core MM callers. - "mm/sparse: remove SECTION_MARKED_PRESENT and further cleanups" (David Hildenbrand): Remove SECTION_MARKED_PRESENT in favor of the early-section flag. Simplify sparse memory initialization, section metadata handling and related PFN validity checks. - "sh: remove NUMA and SPARSEMEM support" (Mike Rapoport): Remove SuperH NUMA and SPARSEMEM support. The extra memory banks have been unusable since the NO_BOOTMEM conversion, leaving only the code and data overhead. - "mm: Unify device DAX and HugeTLB vmemmap population paths" (Muchun Song): Unify the generic device DAX and HugeTLB vmemmap population paths and shared tail-page handling. Remove the duplicate DAX machinery while retaining the powerpc radix implementation. - "kselftest: mm: fix some failure of split_huge_page_test" (Yeoreum Yun): Fix huge-page split tests racing with khugepaged recollapse. Use pagemap and page flags instead of VMA-boundary assumptions which fail when glibc has already enabled THP. - "memcg: move memcgid refcount to objcg to unpin dying memcgs" (Bingfang Guo): Let dying memcgs be freed while swapped-out shmem still holds their IDs. Move ID references to reparentable objcgs, with the necessary swap accounting and RCU lifetime changes. - "mm/truncate: fix data loss when truncating straddling large folios" (Zhang Yi): Preserve out-of-range data when truncating straddling large folios. Fix a lookup race and split-failure handling, and handle minimum folio orders for the forthcoming ext4 iomap buffered I/O path. - "mm/damon: introduce damos quota goal target metric complement flag" (SJ Park): Let DAMOS quota goals use a metric's complement, so utilization can also express free-memory goals without adding separate metrics. Add the sysfs interface, documentation and tests. - "arm64/mm: Standardize printing for pgtable entries" (Anshuman Khandual): Use the generic formatter for arm64 page-table entries, ready for future wider entries. Move the safe-PTE-update check out of the header to avoid an include cycle. - "mm: kmsan: fix iounmap metadata teardown" (Dima Koziuk): Fix KMSAN metadata leaks on iounmap and failed ioremap allocations. Free backing pages before removing their mappings, and share the teardown with partial-allocation cleanup. - "mm/damon/core: preserve quota state when constructing schemes" (Karl Mehltretter): Preserve running DAMOS quota state while validating parameter updates. Even rejected updates could reset accounting and exceed the quota window; add tests for both accepted and rejected updates. - "mm/vmalloc: fix vmalloc_dump_obj VA lookup" (Ye Liu): Fix vmalloc_dump_obj() lookups for last-page addresses and allocations spanning vmap zones. These allocations were being missed in diagnostic output. - "mm: various (urgent?) fixes" (David Hildenbrand): Fix mmap charge leaks and hugetlb use-after-free, wrong-address unmapping, stuck locks and endless faults. Also preserve reservations on failed mremap and handle stale userfaultfd bits. - "maple_tree: fix maple_range_64 crashes in RCU mode" (Dimitris Charisis): Fix pointer and metadata confusion during RCU destruction of maple_range_64 nodes, avoiding double frees and invalid accesses. Add a regression test; no in-tree user currently uses this combination. - "mm: fix hugetlb NR_HUGETLB accounting on folio migration" (Hongfu Li): Fix hugetlb migration and preallocation accounting so /proc/vmstat retains the correct count and memory.numa_stat follows the folio to its new node. - "mm/damon: fix a minor bug, clean code, and add a test" (SJ Park): Fix 32-bit DAMON age overflow which made old regions look young. Share hugetlb folio acquisition code and add a regression test for the previously fixed last-region skipping bug. - "mm/damon/core: cleanup code, reduce stack usage, and add kunit" (SJ Park): Reduce kdamond stack usage and remove unused enums. Add deterministic PSI quota-goal tests which do not depend on the machine's current memory pressure. - "mm/damon: fix the temporal goal tuner's size quota conversion" (Donggeun Yoo): Bound the temporal tuner's quota conversion to prevent overflow and zero effective quotas, which could stop schemes making progress. Add boundary tests. - "Don't use GFP_DMA when calling dma_alloc_coherent" (Baoquan He): Remove redundant GFP_DMA flags from coherent DMA allocation calls. The DMA API already selects the zone from device limits and ignores the caller's flag. - "kselftest: mm: fix intermittent failure khugepaged test" (Yeoreum Yun): Propagate child-process failures in the khugepaged tests and prevent background collapse from racing their checks. This removes false passes and intermittent failures. - "MAINTAINERS: cover all hugetlb headers under HUGETLB SUBSYSTEM" (Enze Li): Cover all hugetlb headers in MAINTAINERS so get_maintainer.pl finds the right maintainers. Also label the closing hugetlb_cgroup.h include guard. Summary of the 65 singletons in this merge: The singletons include a few worthwhile performance fixes. Avoiding unnecessary reverse-map tree updates gave a reported 15.9% improvement in UnixBench's execl test on a 192-core x86 system. A reclaim retry fix stops defrag_mode from spinning under memory.low protection; a reported file-creation stress test ran 5.7 times faster, with far less memory pressure. Narrower hugetlb invalidations also spare KVM guests needless refaults: the reported Redis-in-VM P99 QPS penalty while punching holes fell from 7.09% to 1.45%. Several fixes prevent lost data or corrupted memory. Lazyfree huge-page races with mremap()/munmap() could lose data or access freed memory, and MADV_COLD could lose a concurrent write's dirty bit. Another fix prevents stale migration entries from outliving large folios. On filesystems with blocks smaller than a page, extending a file by 4 GiB or more could expose bytes written past the old EOF through mmap instead of zeroes. That is fixed, along with use-after-free races in PAGEMAP_SCAN during process exit and in memory-cgroup accounting on PREEMPT_RT kernels. Other fixes stop UFFDIO_MOVE spinning forever on pinned large folios, which could wedge other memory operations, and stop mremap() leaking commit charges until allocations fail under strict overcommit. A further fix keeps userfaultfd tracking intact on neighboring mappings. NUMA binding no longer prevents long-term pins when the chosen node has only movable memory, fixing QEMU/VFIO startup and io_uring buffer registration failures. MGLRU also gets a fix for early-boot crashes with memory cgroups disabled at boot, notably in small crash kernels. * tag 'mm-stable-2026-10-25-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (213 commits) mm: multi-gen LRU: fix NULL lruvec->pgdat deref with memcg disabled on cmdline mm/page_counter: use WRITE_ONCE() for emin/elow when parent is the root mm/memcontrol: publish null pointer before dropping css reference test_maple_tree: test maple_range_64 node in RCU mode maple_tree: fix maple_range_64 crashes in RCU mode mm/vma: avoid broken uffd merge on mremap tools/testing/shared: catch a failed posix_memalign() mm/damon/core: remove unreachable damos charge_{target,addr}_from mm/shrinker: allocate shrinker_info_unit from a dedicated kmem_cache riscv: mm: exclude invalid THP PMDs from page table check mm/damon/core: filter out damos address filter-split failed region fs/proc/task_mmu: pin mm_users in do_pagemap_scan() mm/mempolicy: apply bind policies against the scoped allocation zone mm/vmscan: reclaim every zone in per-node proactive reclaim mm/mremap: correctly uncharge accountable VMAs in error path mm/mremap: populate calculated fields in vrm state correctly MAINTAINERS: add an entry for MEMORY MANAGEMENT - MEMORY MAP mm: bdi: reset min_ratio after the sysfs attributes are gone mm/page_vma_mapped: continue past nonmatching huge PMDs selftests/mm: skip hugetlb cgroup v2 tests without the needed controllers ... 
Pull more MM updates from Andrew Morton:

 - "mm: make VMA flag semantics explicit, eliminate VM_SPECIAL" (Lorenzo
   Stoakes):

   Replace VM_SPECIAL with helpers describing mapping ownership and
   behavior. Enforce the mmap flag rules and convert affected drivers,
   removing ambiguous tests shared by driver mappings and ordinary
   memory.

 - "support kselftest on nommu platform" (Hajime Tazaki):

   Add opt-in mmap and mremap tests for NOMMU systems. Teach the runner
   to avoid its fork-dependent timeout command and document the build
   and runtime requirements.

 - "mm/collapse: separate a collapse from its callers" (Kiryl
   Shutsemau):

   Separate huge-page collapse from caller policy. Replace khugepaged
   identity checks with explicit permissions, and separate scanning from
   collapse with the mmap_lock drop in one place.

 - "mm: implement and use vma_has_anon_rmap(), silence KCSAN" (Lorenzo
   Stoakes):

   Provide a common helper for testing whether a VMA has anonymous
   reverse mappings. Document the locking rules, annotate intentional
   concurrent reads for KCSAN, and convert the core MM callers.

 - "mm/sparse: remove SECTION_MARKED_PRESENT and further cleanups"
   (David Hildenbrand):

   Remove SECTION_MARKED_PRESENT in favor of the early-section flag.
   Simplify sparse memory initialization, section metadata handling and
   related PFN validity checks.

 - "sh: remove NUMA and SPARSEMEM support" (Mike Rapoport):

   Remove SuperH NUMA and SPARSEMEM support. The extra memory banks have
   been unusable since the NO_BOOTMEM conversion, leaving only the code
   and data overhead.

 - "mm: Unify device DAX and HugeTLB vmemmap population paths" (Muchun
   Song):

   Unify the generic device DAX and HugeTLB vmemmap population paths and
   shared tail-page handling. Remove the duplicate DAX machinery while
   retaining the powerpc radix implementation.

 - "kselftest: mm: fix some failure of split_huge_page_test" (Yeoreum
   Yun):

   Fix huge-page split tests racing with khugepaged recollapse. Use
   pagemap and page flags instead of VMA-boundary assumptions which fail
   when glibc has already enabled THP.

 - "memcg: move memcgid refcount to objcg to unpin dying memcgs"
   (Bingfang Guo):

   Let dying memcgs be freed while swapped-out shmem still holds their
   IDs. Move ID references to reparentable objcgs, with the necessary
   swap accounting and RCU lifetime changes.

 - "mm/truncate: fix data loss when truncating straddling large folios"
   (Zhang Yi):

   Preserve out-of-range data when truncating straddling large folios.
   Fix a lookup race and split-failure handling, and handle minimum
   folio orders for the forthcoming ext4 iomap buffered I/O path.

 - "mm/damon: introduce damos quota goal target metric complement flag"
   (SJ Park):

   Let DAMOS quota goals use a metric's complement, so utilization can
   also express free-memory goals without adding separate metrics. Add
   the sysfs interface, documentation and tests.

 - "arm64/mm: Standardize printing for pgtable entries" (Anshuman
   Khandual):

   Use the generic formatter for arm64 page-table entries, ready for
   future wider entries. Move the safe-PTE-update check out of the
   header to avoid an include cycle.

 - "mm: kmsan: fix iounmap metadata teardown" (Dima Koziuk):

   Fix KMSAN metadata leaks on iounmap and failed ioremap allocations.
   Free backing pages before removing their mappings, and share the
   teardown with partial-allocation cleanup.

 - "mm/damon/core: preserve quota state when constructing schemes" (Karl
   Mehltretter):

   Preserve running DAMOS quota state while validating parameter
   updates. Even rejected updates could reset accounting and exceed the
   quota window; add tests for both accepted and rejected updates.

 - "mm/vmalloc: fix vmalloc_dump_obj VA lookup" (Ye Liu):

   Fix vmalloc_dump_obj() lookups for last-page addresses and
   allocations spanning vmap zones. These allocations were being missed
   in diagnostic output.

 - "mm: various (urgent?) fixes" (David Hildenbrand):

   Fix mmap charge leaks and hugetlb use-after-free, wrong-address
   unmapping, stuck locks and endless faults. Also preserve reservations
   on failed mremap and handle stale userfaultfd bits.

 - "maple_tree: fix maple_range_64 crashes in RCU mode" (Dimitris
   Charisis):

   Fix pointer and metadata confusion during RCU destruction of
   maple_range_64 nodes, avoiding double frees and invalid accesses. Add
   a regression test; no in-tree user currently uses this combination.

 - "mm: fix hugetlb NR_HUGETLB accounting on folio migration" (Hongfu
   Li):

   Fix hugetlb migration and preallocation accounting so /proc/vmstat
   retains the correct count and memory.numa_stat follows the folio to
   its new node.

 - "mm/damon: fix a minor bug, clean code, and add a test" (SJ Park):

   Fix 32-bit DAMON age overflow which made old regions look young.
   Share hugetlb folio acquisition code and add a regression test for
   the previously fixed last-region skipping bug.

 - "mm/damon/core: cleanup code, reduce stack usage, and add kunit" (SJ
   Park):

   Reduce kdamond stack usage and remove unused enums. Add deterministic
   PSI quota-goal tests which do not depend on the machine's current
   memory pressure.

 - "mm/damon: fix the temporal goal tuner's size quota conversion"
   (Donggeun Yoo):

   Bound the temporal tuner's quota conversion to prevent overflow and
   zero effective quotas, which could stop schemes making progress. Add
   boundary tests.

 - "Don't use GFP_DMA when calling dma_alloc_coherent" (Baoquan He):

   Remove redundant GFP_DMA flags from coherent DMA allocation calls.
   The DMA API already selects the zone from device limits and ignores
   the caller's flag.

 - "kselftest: mm: fix intermittent failure khugepaged test" (Yeoreum
   Yun):

   Propagate child-process failures in the khugepaged tests and prevent
   background collapse from racing their checks. This removes false
   passes and intermittent failures.

 - "MAINTAINERS: cover all hugetlb headers under HUGETLB SUBSYSTEM"
   (Enze Li):

   Cover all hugetlb headers in MAINTAINERS so get_maintainer.pl finds
   the right maintainers. Also label the closing hugetlb_cgroup.h
   include guard.

Summary of the 65 singletons in this merge:

  The singletons include a few worthwhile performance fixes. Avoiding
  unnecessary reverse-map tree updates gave a reported 15.9% improvement
  in UnixBench's execl test on a 192-core x86 system. A reclaim retry
  fix stops defrag_mode from spinning under memory.low protection; a
  reported file-creation stress test ran 5.7 times faster, with far less
  memory pressure. Narrower hugetlb invalidations also spare KVM guests
  needless refaults: the reported Redis-in-VM P99 QPS penalty while
  punching holes fell from 7.09% to 1.45%.

  Several fixes prevent lost data or corrupted memory. Lazyfree
  huge-page races with mremap()/munmap() could lose data or access freed
  memory, and MADV_COLD could lose a concurrent write's dirty bit.
  Another fix prevents stale migration entries from outliving large
  folios. On filesystems with blocks smaller than a page, extending a
  file by 4 GiB or more could expose bytes written past the old EOF
  through mmap instead of zeroes. That is fixed, along with
  use-after-free races in PAGEMAP_SCAN during process exit and in
  memory-cgroup accounting on PREEMPT_RT kernels.

  Other fixes stop UFFDIO_MOVE spinning forever on pinned large folios,
  which could wedge other memory operations, and stop mremap() leaking
  commit charges until allocations fail under strict overcommit. A
  further fix keeps userfaultfd tracking intact on neighboring mappings.
  NUMA binding no longer prevents long-term pins when the chosen node
  has only movable memory, fixing QEMU/VFIO startup and io_uring buffer
  registration failures. MGLRU also gets a fix for early-boot crashes
  with memory cgroups disabled at boot, notably in small crash kernels.

* tag 'mm-stable-2026-10-25-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (213 commits)
  mm: multi-gen LRU: fix NULL lruvec->pgdat deref with memcg disabled on cmdline
  mm/page_counter: use WRITE_ONCE() for emin/elow when parent is the root
  mm/memcontrol: publish null pointer before dropping css reference
  test_maple_tree: test maple_range_64 node in RCU mode
  maple_tree: fix maple_range_64 crashes in RCU mode
  mm/vma: avoid broken uffd merge on mremap
  tools/testing/shared: catch a failed posix_memalign()
  mm/damon/core: remove unreachable damos charge_{target,addr}_from
  mm/shrinker: allocate shrinker_info_unit from a dedicated kmem_cache
  riscv: mm: exclude invalid THP PMDs from page table check
  mm/damon/core: filter out damos address filter-split failed region
  fs/proc/task_mmu: pin mm_users in do_pagemap_scan()
  mm/mempolicy: apply bind policies against the scoped allocation zone
  mm/vmscan: reclaim every zone in per-node proactive reclaim
  mm/mremap: correctly uncharge accountable VMAs in error path
  mm/mremap: populate calculated fields in vrm state correctly
  MAINTAINERS: add an entry for MEMORY MANAGEMENT - MEMORY MAP
  mm: bdi: reset min_ratio after the sysfs attributes are gone
  mm/page_vma_mapped: continue past nonmatching huge PMDs
  selftests/mm: skip hugetlb cgroup v2 tests without the needed controllers
  ...
Merge tag 'fuse-update-7.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse 2026-10-27T18:09:58+00:00 Linus Torvalds torvalds@linux-foundation.org 2026-10-27T18:09:58+00:00 03973f7f3556b769a3dd5104f166614d446351c9 Pull fuse updates from Miklos Szeredi: - Add dax backing and extent map support for famfs (John Groves, Miklos) - Support large folios (Joanne) - Add selftests and documentation of caching behavior (Luis Henriques) - Add FUSE_SYNCFS request (Jimmy Zuber) - Convert readdir cache to use folios (Tal Zussman) - Lots of bug fixes * tag 'fuse-update-7.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (53 commits) fuse: handle extent map files in fuse_passthrough_fadvise() fuse: resolve extent maps in O(1) when possible fuse: add support for striped backing fuse: add extent map I/O support fuse: add extent map data structure fuse: add support for opening dax device as backing fuse: support opening 64 bit backing ID fuse: support 64 bit, server allocated backing ID fuse: add helpers for EIO return value with kernel message dax: use READ_ONCE() in dax_holder() dax: add fsdev_dax_from_file() fuse: fix copy_file_range reply handling race virtiofs: validate fixed-output response length fuse: don't d_drop() before d_splice_alias() virtio_fs: read the vring size under virtio_fs_mutex in ->get_tree fuse: validate folio state before pipe_buf_try_steal() in fuse_try_move_folio() fuse: rename fuse_direct_io() to fuse_do_direct_io() fuse: Forward vfs_fadvise to backing_file in passthrough mode selftests/fuse: add the missing FUSE_HAS_SYNCFS privilege test fuse: don't launder folios of a bad inode ... 
Pull fuse updates from Miklos Szeredi:

 - Add dax backing and extent map support for famfs (John Groves,
   Miklos)

 - Support large folios (Joanne)

 - Add selftests and documentation of caching behavior (Luis Henriques)

 - Add FUSE_SYNCFS request (Jimmy Zuber)

 - Convert readdir cache to use folios (Tal Zussman)

 - Lots of bug fixes

* tag 'fuse-update-7.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (53 commits)
  fuse: handle extent map files in fuse_passthrough_fadvise()
  fuse: resolve extent maps in O(1) when possible
  fuse: add support for striped backing
  fuse: add extent map I/O support
  fuse: add extent map data structure
  fuse: add support for opening dax device as backing
  fuse: support opening 64 bit backing ID
  fuse: support 64 bit, server allocated backing ID
  fuse: add helpers for EIO return value with kernel message
  dax: use READ_ONCE() in dax_holder()
  dax: add fsdev_dax_from_file()
  fuse: fix copy_file_range reply handling race
  virtiofs: validate fixed-output response length
  fuse: don't d_drop() before d_splice_alias()
  virtio_fs: read the vring size under virtio_fs_mutex in ->get_tree
  fuse: validate folio state before pipe_buf_try_steal() in fuse_try_move_folio()
  fuse: rename fuse_direct_io() to fuse_do_direct_io()
  fuse: Forward vfs_fadvise to backing_file in passthrough mode
  selftests/fuse: add the missing FUSE_HAS_SYNCFS privilege test
  fuse: don't launder folios of a bad inode
  ...
fuse: handle extent map files in fuse_passthrough_fadvise() 2026-10-26T17:10:12+00:00 John Groves john@groves.net 2026-10-22T23:47:47+00:00 bf56861216337c839dce3c8bb1c4be96d30ca716 This addresses a collision between the pending backing_file fadvise patch and the new extent-mapping code for famfs (which falls into the passthrough bucket. A file opened with FOPEN_PASSTHROUGH on an extent map backing has no backing file: fuse_passthrough_open() returns before setting ff->passthrough and ff->cred. fuse_file_fadvise() routes every FOPEN_PASSTHROUGH file to fuse_passthrough_fadvise(), which installed the NULL ff->cred on the task with override_creds() and then passed the NULL backing file to vfs_fadvise(). Any posix_fadvise(), readahead() or madvise(MADV_WILLNEED) on such a file oopsed. fio triggers it at file open with its default invalidate and fadvise_hint settings. Fall back to generic_fadvise() when there is no backing file, as the other passthrough helpers fall back to their extent map or generic implementations. generic_fadvise() already ignores advice on DAX inodes while keeping the EINVAL and ESPIPE checks. Reported-by: Aravind Ramesh <arramesh@micron.com> Fixes: 69f77a06ffad ("fuse: Forward vfs_fadvise to backing_file in passthrough mode") Tested-by: John Groves <john@groves.net> Signed-off-by: John Groves <john@groves.net> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> 
This addresses a collision between the pending backing_file fadvise
patch and the new extent-mapping code for famfs (which falls into the
passthrough bucket.

A file opened with FOPEN_PASSTHROUGH on an extent map backing has no
backing file: fuse_passthrough_open() returns before setting
ff->passthrough and ff->cred.  fuse_file_fadvise() routes every
FOPEN_PASSTHROUGH file to fuse_passthrough_fadvise(), which installed
the NULL ff->cred on the task with override_creds() and then passed the
NULL backing file to vfs_fadvise().  Any posix_fadvise(), readahead()
or madvise(MADV_WILLNEED) on such a file oopsed.  fio triggers it at
file open with its default invalidate and fadvise_hint settings.

Fall back to generic_fadvise() when there is no backing file, as the
other passthrough helpers fall back to their extent map or generic
implementations.  generic_fadvise() already ignores advice on DAX
inodes while keeping the EINVAL and ESPIPE checks.

Reported-by: Aravind Ramesh <arramesh@micron.com>
Fixes: 69f77a06ffad ("fuse: Forward vfs_fadvise to backing_file in passthrough mode")
Tested-by: John Groves <john@groves.net>
Signed-off-by: John Groves <john@groves.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
fuse: dax: do not set VM_MIXEDMAP 2026-10-24T08:56:21+00:00 Lorenzo Stoakes (ARM) ljs@kernel.org 2026-10-13T15:05:18+00:00 b0d88bfa7515ed772afa286af0e2f635acad9f7e Commit e1fb4a086495 ("dax: remove VM_MIXEDMAP for fsdax and device dax") prevented fsdax and device-dax from setting VM_MIXEDMAP, as DAX no longer relies on it to direct core mm paths. The fuse DAX implementation, added later, copied the old pattern and still sets it. Fuse DAX maps pages the same way fsdax does, via dax_iomap_fault() and ultimately vmf_insert_page_mkwrite() and vmf_insert_folio_pmd(), which insert ordinary refcounted pages and so do not require VM_MIXEDMAP. Setting it only serves to mark the mapping as not mm-managed, making fuse DAX the sole DAX implementation whose mappings are unmergeable, cannot be mlock()'d, eagerly copy page tables on fork and reject MADV_DOFORK and MADV_DODUMP. It also requires vma_is_special_huge() in mm/huge_memory.c to carve DAX out of its check for mappings not managed by core mm explicitly. There is no reason for fuse DAX to keep on using this flag so drop it. Link: https://lore.kernel.org/20261013-b4-mmap-prepare-vma-flag-sanify-v6-38-1aa3c9b139f9@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Hildenbrand (Arm) <david@kernel.org> Cc: Liam R. Howlett <liam@infradead.org> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Jann Horn <jannh@google.com> Cc: Pedro Falcato <pfalcato@suse.de> Cc: Mike Rapoport <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Leon Romanovsky <leon@kernel.org> Cc: Paul Moore <paul@paul-moore.com> Cc: Stephen Smalley <stephen.smalley.work@gmail.com> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Takashi Iwai <tiwai@suse.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Eduard Zingerman <eddyz87@gmail.com> Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Nico Pache <nico.pache@linux.dev> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Dev Jain <dev.jain@arm.com> Cc: Barry Song <baohua@kernel.org> Cc: Lance Yang <lance.yang@linux.dev> Cc: Usama Arif <usama.arif@linux.dev> Cc: Kiryl Shutsemau <kas@kernel.org> Cc: Doug Gilbert <dgilbert@interlog.com> Cc: James Bottomley <james.bottomley@hansenpartnership.com> Cc: Martin K. Petersen <mkp@kernel.org> Cc: Simona Vetter <simona@ffwll.ch> Cc: Helge Deller <deller@gmx.de> Cc: Sebastian Reichel <sre@kernel.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Peter Xu <peterx@redhat.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Rik van Riel <riel@surriel.com> Cc: Harry Yoo <harry@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: David Airlie <airlied@gmail.com> Cc: Will Deacon <will@kernel.org> Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Muchun Song <muchun.song@linux.dev> Cc: Oscar Salvador <osalvador@suse.de> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Jan Kara <jack@suse.cz> Cc: Marc Zyngier <maz@kernel.org> Cc: Oliver Upton <oupton@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Madhavan Srinivasan <maddy@linux.ibm.com> Cc: Anup Patel <anup@brainfault.org> Cc: Paul Walmsley <pjw@kernel.org> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Janosch Frank <frankja@linux.ibm.com> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Andreas Larsson <andreas@gaisler.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Matthew Brost <matthew.brost@intel.com> Cc: Joshua Hahn <joshua.hahnjy@gmail.com> Cc: Rakie Kim <rakie.kim@sk.com> Cc: Byungchul Park <byungchul@sk.com> Cc: Gregory Price <gourry@gourry.net> Cc: Ying Huang <ying.huang@linux.alibaba.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Chris Li <chrisl@kernel.org> Cc: Kairui Song <kasong@tencent.com> Cc: Kemeng Shi <shikemeng@huaweicloud.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Baoquan He <baoquan.he@linux.dev> Cc: Youngjun Park <youngjun.park@lge.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Qi Zheng <qi.zheng@linux.dev> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Wei Xu <weixugc@google.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Michal Hocko <mhocko@kernel.org> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Xu Xin <xu.xin@linux.dev> Cc: Ihor Solodrai <ihor.solodrai@linux.dev> Cc: Bert Karwatzki <spasswolf@web.de> 
Commit e1fb4a086495 ("dax: remove VM_MIXEDMAP for fsdax and device dax")
prevented fsdax and device-dax from setting VM_MIXEDMAP, as DAX no longer
relies on it to direct core mm paths.

The fuse DAX implementation, added later, copied the old pattern and still
sets it.

Fuse DAX maps pages the same way fsdax does, via dax_iomap_fault() and
ultimately vmf_insert_page_mkwrite() and vmf_insert_folio_pmd(), which
insert ordinary refcounted pages and so do not require VM_MIXEDMAP.

Setting it only serves to mark the mapping as not mm-managed, making fuse
DAX the sole DAX implementation whose mappings are unmergeable, cannot be
mlock()'d, eagerly copy page tables on fork and reject MADV_DOFORK and
MADV_DODUMP.

It also requires vma_is_special_huge() in mm/huge_memory.c to carve DAX out
of its check for mappings not managed by core mm explicitly.

There is no reason for fuse DAX to keep on using this flag so drop it.

Link: https://lore.kernel.org/20261013-b4-mmap-prepare-vma-flag-sanify-v6-38-1aa3c9b139f9@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Nico Pache <nico.pache@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Kiryl Shutsemau <kas@kernel.org>
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: James Bottomley <james.bottomley@hansenpartnership.com>
Cc: Martin K. Petersen <mkp@kernel.org>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Helge Deller <deller@gmx.de>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Harry Yoo <harry@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oupton@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Anup Patel <anup@brainfault.org>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Qi Zheng <qi.zheng@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Xu Xin <xu.xin@linux.dev>
Cc: Ihor Solodrai <ihor.solodrai@linux.dev>
Cc: Bert Karwatzki <spasswolf@web.de>
fuse: resolve extent maps in O(1) when possible 2026-10-20T04:39:59+00:00 John Groves john@groves.net 2026-10-11T22:34:56+00:00 5a9745611d621ea160854936eb6370e610887bfb fuse_ext_map_iomap_begin() runs on every mapping fault of a DAX extent-mapped file, meaning the TLB-miss-plus-page-table-miss case, and on every chunk of every read/write. These are not page faults in the usual sense: nothing is read in from storage. The fault only installs page table entries for memory that is already there, so there is no I/O to amortize the resolver's cost against; whatever it costs is added to the cost of a memory access. The rbtree it walks is built from individually allocated nodes. Each level is a dependent, un-prefetchable dereference and a potential LLC miss (~100ns), so a striped file with S strips pays log2(S) of them per resolution, and that is a large fraction of a mapping fault that otherwise costs little more than the page table update itself. Replace the rbtree in struct fuse_backing with a packed, sorted array of fuse_iext extents, allocated once per map rather than once per extent. The array packs the extents into the fewest cache lines, and fault handling is O(1) when the map allows it: - A cyclic (striped) map is required to have equal-length extents contiguous from zero, so a file offset converts arithmetically to a strip index and cycle number. This patch validates that and does it. - A simple map whose extents happen to be equal-length and contiguous from zero (the common famfs allocation) resolves as offset / ext_len. This patch detects that at populate time and does it. - An irregular map falls back to a binary search of the packed array. famfs currently always produces maps that resolve in O(1). Because the extents are sorted at populate time, a cyclic map's extents no longer have to arrive in offset order, and the overlap check is an adjacent-pair compare over the sorted array rather than a check at each rbtree insertion. Error returns are unchanged: -EIO with a message for malformed extents and overlaps, -EINVAL for a non-uniform cyclic map. Signed-off-by: John Groves <john@groves.net> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> 
fuse_ext_map_iomap_begin() runs on every mapping fault of a DAX
extent-mapped file, meaning the TLB-miss-plus-page-table-miss case,
and on every chunk of every read/write.  These are not page faults in
the usual sense: nothing is read in from storage.  The fault only
installs page table entries for memory that is already there, so there
is no I/O to amortize the resolver's cost against; whatever it costs
is added to the cost of a memory access.

The rbtree it walks is built from individually allocated nodes.  Each
level is a dependent, un-prefetchable dereference and a potential LLC
miss (~100ns), so a striped file with S strips pays log2(S) of them
per resolution, and that is a large fraction of a mapping fault that
otherwise costs little more than the page table update itself.

Replace the rbtree in struct fuse_backing with a packed, sorted array
of fuse_iext extents, allocated once per map rather than once per
extent.  The array packs the extents into the fewest cache lines, and
fault handling is O(1) when the map allows it:

 - A cyclic (striped) map is required to have equal-length extents
   contiguous from zero, so a file offset converts arithmetically to a
   strip index and cycle number.  This patch validates that and does
   it.

 - A simple map whose extents happen to be equal-length and contiguous
   from zero (the common famfs allocation) resolves as offset / ext_len.
   This patch detects that at populate time and does it.

 - An irregular map falls back to a binary search of the packed array.

famfs currently always produces maps that resolve in O(1).

Because the extents are sorted at populate time, a cyclic map's extents
no longer have to arrive in offset order, and the overlap check is an
adjacent-pair compare over the sorted array rather than a check at each
rbtree insertion.  Error returns are unchanged: -EIO with a message for
malformed extents and overlaps, -EINVAL for a non-uniform cyclic map.

Signed-off-by: John Groves <john@groves.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Merge tag 'vfs-7.4-rc1.idmap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs 2026-10-20T03:57:49+00:00 Linus Torvalds torvalds@linux-foundation.org 2026-10-20T03:57:49+00:00 00b04f4495c354cad82f96d41947aa70f71e2cc4 Pull vfs idmap constification from Christian Brauner: "This makes struct mnt_idmap const throughout the tree. A mount's idmapping is immutable. The only thing modified after alloc_mnt_idmap() is the reference count and that is hidden behind mnt_idmap_get() and mnt_idmap_put(). Everything else only reads from it. That is the same model struct cred uses and the idmapping is sensitive enough to deserve it. The conversion goes bottom up through the vfs{g,u}id and fs{g,u}id helpers, the privilege checks, acl, xattr and quota and then every inode operation that takes an idmap, so ->permission(), ->getattr(), ->setattr(), ->create(), ->mkdir(), ->mknod(), ->symlink(), ->rename(), ->tmpfile(), ->get_acl(), ->set_acl() and ->fileattr_set() with their implementations in every filesystem, plus the LSM hooks. struct vfsmount, struct mount_kattr and struct kstatmount store a const pointer and nop_mnt_idmap and invalid_mnt_idmap live in rodata, so anything that tries to modify them faults instead of silently corrupting the initial idmapping" * tag 'vfs-7.4-rc1.idmap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (27 commits) fs: make nop_mnt_idmap and invalid_mnt_idmap const fs: port mnt_idmap() and file_mnt_idmap() to const mnt_idmap fs: port vfs_*() helpers to const mnt_idmap fs: port ->setattr() to pass const mnt_idmap fs: port ->getattr() to pass const mnt_idmap fs: port ->create() to pass const mnt_idmap fs: port ->symlink() to pass const mnt_idmap fs: port ->mkdir() to pass const mnt_idmap fs: port ->rename() to pass const mnt_idmap fs: port ->mknod() to pass const mnt_idmap fs: port ->tmpfile() to pass const mnt_idmap fs: port ->get_acl() to pass const mnt_idmap fs: port ->set_acl() to pass const mnt_idmap fs: port ->fileattr_set() to pass const mnt_idmap fs: port xattr to const mnt_idmap fs: port ->permission() to pass const mnt_idmap fs: port acl to const mnt_idmap fs: port inode_init_owner() to const mnt_idmap fs: port inode_owner_or_capable() to const mnt_idmap fs: port privilege checking helpers to const mnt_idmap ... 
Pull vfs idmap constification from Christian Brauner:
 "This makes struct mnt_idmap const throughout the tree.

  A mount's idmapping is immutable. The only thing modified after
  alloc_mnt_idmap() is the reference count and that is hidden behind
  mnt_idmap_get() and mnt_idmap_put(). Everything else only reads from
  it. That is the same model struct cred uses and the idmapping is
  sensitive enough to deserve it.

  The conversion goes bottom up through the vfs{g,u}id and fs{g,u}id
  helpers, the privilege checks, acl, xattr and quota and then every
  inode operation that takes an idmap, so ->permission(), ->getattr(),
  ->setattr(), ->create(), ->mkdir(), ->mknod(), ->symlink(),
  ->rename(), ->tmpfile(), ->get_acl(), ->set_acl() and ->fileattr_set()
  with their implementations in every filesystem, plus the LSM hooks.

  struct vfsmount, struct mount_kattr and struct kstatmount store a
  const pointer and nop_mnt_idmap and invalid_mnt_idmap live in rodata,
  so anything that tries to modify them faults instead of silently
  corrupting the initial idmapping"

* tag 'vfs-7.4-rc1.idmap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (27 commits)
  fs: make nop_mnt_idmap and invalid_mnt_idmap const
  fs: port mnt_idmap() and file_mnt_idmap() to const mnt_idmap
  fs: port vfs_*() helpers to const mnt_idmap
  fs: port ->setattr() to pass const mnt_idmap
  fs: port ->getattr() to pass const mnt_idmap
  fs: port ->create() to pass const mnt_idmap
  fs: port ->symlink() to pass const mnt_idmap
  fs: port ->mkdir() to pass const mnt_idmap
  fs: port ->rename() to pass const mnt_idmap
  fs: port ->mknod() to pass const mnt_idmap
  fs: port ->tmpfile() to pass const mnt_idmap
  fs: port ->get_acl() to pass const mnt_idmap
  fs: port ->set_acl() to pass const mnt_idmap
  fs: port ->fileattr_set() to pass const mnt_idmap
  fs: port xattr to const mnt_idmap
  fs: port ->permission() to pass const mnt_idmap
  fs: port acl to const mnt_idmap
  fs: port inode_init_owner() to const mnt_idmap
  fs: port inode_owner_or_capable() to const mnt_idmap
  fs: port privilege checking helpers to const mnt_idmap
  ...
fuse: add support for striped backing 2026-10-19T12:56:24+00:00 Miklos Szeredi mszeredi@redhat.com 2026-09-21T11:12:23+00:00 dfc68b6c99f094e06f720b57cf4ee3d0ae5dbe8f Add the FUSE_BACKING_MAP_CYCLIC flag for FUSE_NOTIFY_BACKING_MAP notifications to enable creating striped maps. This is just a set of regular extents that repeats after the end of the last extent using a striping pattern (i.e. on the target backings the stripes have a contiguous footprint). Two additional limits apply compared to non-cyclic extent map population: - the size of the extents (chunk size) must be equal - the extents must start from zero offset and follow each other without gaps. Originally-by: John Groves <john@groves.net> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> 
Add the FUSE_BACKING_MAP_CYCLIC flag for FUSE_NOTIFY_BACKING_MAP
notifications to enable creating striped maps.

This is just a set of regular extents that repeats after the end of the
last extent using a striping pattern (i.e. on the target backings the
stripes have a contiguous footprint).

Two additional limits apply compared to non-cyclic extent map population:

 - the size of the extents (chunk size) must be equal

 - the extents must start from zero offset and follow each other without
   gaps.

Originally-by: John Groves <john@groves.net>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
fuse: add extent map I/O support 2026-10-19T12:56:24+00:00 Miklos Szeredi mszeredi@redhat.com 2026-09-21T11:11:44+00:00 e8bc74b6ed1b107f67ee7c362e9f6c1b035e2fe9 Wire up read, write, splice and mmap operations for extent-mapped files through the iomap/DAX infrastructure. When a passthrough file is opened with an EXTMAP backing, I/O is dispatched to the dax devices referenced by the extent map. If an address is not mapped, EIO is returned on the I/O operation. Originally-by: John Groves <john@groves.net> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> 
Wire up read, write, splice and mmap operations for extent-mapped
files through the iomap/DAX infrastructure.

When a passthrough file is opened with an EXTMAP backing, I/O is
dispatched to the dax devices referenced by the extent map.

If an address is not mapped, EIO is returned on the I/O operation.

Originally-by: John Groves <john@groves.net>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
fuse: add extent map data structure 2026-10-19T12:56:24+00:00 Miklos Szeredi mszeredi@redhat.com 2026-09-21T11:06:40+00:00 bf75733445820e511ca0b9158a639f6c255eaf7d Add support for creating and managing extent maps that map file regions to dax device regions. Introduce FUSE_NOTIFY_BACKING_MAP for populating extent maps from userspace. Extent maps are handled as a new type of backing and are assigned a 64 bit backing ID by the server. One extent consists of - offset within the containing backing - length of extent - target backing ID - offset into target backing Extents must be non-overlapping, and can only refer to dax device backings for now. At this point only support creating and populating the extent map in one operation, though the interface is not limited by this and later may be changed, so that partial population of an extent map would be possible. Originally-by: John Groves <john@groves.net> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> 
Add support for creating and managing extent maps that map file regions to
dax device regions.

Introduce FUSE_NOTIFY_BACKING_MAP for populating extent maps from
userspace.

Extent maps are handled as a new type of backing and are assigned a 64 bit
backing ID by the server.

One extent consists of

 - offset within the containing backing
 - length of extent
 - target backing ID
 - offset into target backing

Extents must be non-overlapping, and can only refer to dax device backings
for now.

At this point only support creating and populating the extent map in one
operation, though the interface is not limited by this and later may be
changed, so that partial population of an extent map would be possible.

Originally-by: John Groves <john@groves.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>