... or visible outside of audit, really. Note that references
held in delayed_filename always have refcount 1, and from the
moment of complete_getname() or equivalent point in getname...()
there won't be any references to struct filename instance left
in places visible to other threads.
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There are two filename-related problems in io_uring and its
interplay with audit.
Filenames are imported when request is submitted and used when
it is processed. Unfortunately, the latter may very well
happen in a different thread. In that case the reference to
filename is put into the wrong audit_context - that of submitting
thread, not the processing one. Audit logics is called by
the latter, and it really wants to be able to find the names
in audit_context current (== processing) thread.
Another related problem is the headache with refcounts -
normally all references to given struct filename are visible
only to one thread (the one that uses that struct filename).
io_uring violates that - an extra reference is stashed in
audit_context of submitter. It gets dropped when submitter
returns to userland, which can happen simultaneously with
processing thread deciding to drop the reference it got.
We paper over that by making refcount atomic, but that means
pointless headache for everyone.
Solution: the notion of partially imported filenames. Namely,
already copied from userland, but *not* exposed to audit yet.
io_uring can create that in submitter thread, and complete the
import (obtaining the usual reference to struct filename) in
processing thread.
Object: struct delayed_filename.
Primitives for working with it:
delayed_getname(&delayed_filename, user_string) - copies the name from
userland, returning 0 and stashing the address of (still incomplete)
struct filename in delayed_filename on success and returning -E... on
error.
delayed_getname_uflags(&delayed_filename, user_string, atflags) -
similar, in the same relation to delayed_getname() as getname_uflags()
is to getname()
complete_getname(&delayed_filename) - completes the import of filename
stashed in delayed_filename and returns struct filename to caller,
emptying delayed_filename.
CLASS(filename_complete_delayed, name)(&delayed_filename) - variant of
CLASS(filename) with complete_getname() for constructor.
dismiss_delayed_filename(&delayed_filename) - destructor; drops whatever
might be stashed in delayed_filename, emptying it.
putname_to_delayed(&delayed_filename, name) - if name is shared, stashes
its copy into delayed_filename and drops the reference to name, otherwise
stashes the name itself in there.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Always allocate struct filename from names_cachep, long name or short;
short names would be embedded into struct filename. Longer ones do
not cannibalize the original struct filename - put them into kmalloc'ed
buffers (PATH_MAX-sized for import from userland, strlen() + 1 - for
ones originating kernel-side, where we know the length beforehand).
Cutoff length for short names is chosen so that struct filename would be
192 bytes long - that's both a multiple of 64 and large enough to cover
the majority of real-world uses.
Simplifies logics in getname()/putname() and friends.
[fixed an embarrassing braino in EMBEDDED_NAME_MAX, first reported by
Dan Carpenter]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Instances of struct filename come from names_cachep (via
__getname()). That is done by getname_flags() and getname_kernel()
and these two are the main callers of __getname(). However, there are
other callers that simply want to allocate PATH_MAX bytes for uses that
have nothing to do with struct filename.
We want saner allocation rules for long pathnames, so that struct
filename would *always* come from names_cachep, with the out-of-line
pathname getting kmalloc'ed. For that we need to be able to change the
size of objects allocated by getname_flags()/getname_kernel().
That requires the rest of __getname() users to stop using
names_cachep; we could explicitly switch all of those to kmalloc(),
but that would cause quite a bit of noise. So the plan is to switch
getname_...() to new helpers and turn __getname() into a wrapper for
kmalloc(). Remaining __getname() users could be converted to explicit
kmalloc() at leisure, hopefully along with figuring out what size do
they really want - PATH_MAX is an overkill for some of them, used out
of laziness ("we have a convenient helper that does 4K allocations and
that's large enough, let's use it").
As a side benefit, names_cachep is no longer used outside
of fs/namei.c, so we can move it there and be done with that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Originally we tried to avoid multiple insertions into audit names array
during retry loop by a cute hack - memorize the userland pointer and
if there already is a match, just grab an extra reference to it.
Cute as it had been, it had problems - two identical pointers had
audit aux entries merged, two identical strings did not. Having
different behaviour for syscalls that differ only by addresses of
otherwise identical string arguments is obviously wrong - if nothing
else, compiler can decide to merge identical string literals.
Besides, this hack does nothing for non-audited processes - they get
a fresh copy for retry. It's not time-critical, but having behaviour
subtly differ that way is bogus.
These days we have very few places that import filename more than once
(9 functions total) and it's easy to massage them so we get rid of all
re-imports. With that done, we don't need audit_reusename() anymore.
There's no need to memorize userland pointer either.
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Not all users match that model, but most of them do. By the end of
the series we'll be left with very few irregular ones...
Added:
CLASS(filename, name)(user_path) =>
getname(user_path)
CLASS(filename_kernel, name)(string) =>
getname_kernel(string)
CLASS(filename_flags, name)(user_path, flags) =>
getname_flags(user_path, flags)
CLASS(filename_uflags, name)(user_path, flags) =>
getname_uflags(user_path, flags)
CLASS(filename_maybe_null, name)(user_path, flags) =>
getname_maybe_null(user_path, flags)
all with putname() as destructor.
"flags" in filename_flags is in LOOKUP_... space, only LOOKUP_EMPTY matters.
"flags" in filename_uflags and filename_maybe_null is in AT_...... space,
and only AT_EMPTY_PATH matters.
filename_flags conventions might be worth reconsidering later (it might or
might not be better off with boolean instead)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
maple_tree insertions can fail if we are seriously short on memory;
simple_offset_rename() does not recover well if it runs into that.
The same goes for simple_offset_rename_exchange().
Moreover, shmem_whiteout() expects that if it succeeds, the caller will
progress to d_move(), i.e. that shmem_rename2() won't fail past the
successful call of shmem_whiteout().
Not hard to fix, fortunately - mtree_store() can't fail if the index we
are trying to store into is already present in the tree as a singleton.
For simple_offset_rename_exchange() that's enough - we just need to be
careful about the order of operations.
For simple_offset_rename() solution is to preinsert the target into the
tree for new_dir; the rest can be done without any potentially failing
operations.
That preinsertion has to be done in shmem_rename2() rather than in
simple_offset_rename() itself - otherwise we'd need to deal with the
possibility of failure after successful shmem_whiteout().
Fixes: a2e459555c ("shmem: stable directory offsets")
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
dentries of created objects in dcache (and undo it when removing those).
Reference is grabbed and not released, but it's not actually _stored_
anywhere. That works, but it's hard to follow and verify; among other
things, we have no way to tell _which_ of the increments is intended
to be an unpaired one. Worse, on removal we need to decide whether
the reference had already been dropped, which can be non-trivial if
that removal is on umount and we need to figure out if this dentry is
pinned due to e.g. unlink() not done. Usually that is handled by using
kill_litter_super() as ->kill_sb(), but there are open-coded special
cases of the same (consider e.g. /proc/self).
Things get simpler if we introduce a new dentry flag (DCACHE_PERSISTENT)
marking those "leaked" dentries. Having it set claims responsibility
for +1 in refcount.
The end result this series is aiming for:
* get these unbalanced dget() and dput() replaced with new primitives that
would, in addition to adjusting refcount, set and clear persistency flag.
* instead of having kill_litter_super() mess with removing the remaining
"leaked" references (e.g. for all tmpfs files that hadn't been removed
prior to umount), have the regular shrink_dcache_for_umount() strip
DCACHE_PERSISTENT of all dentries, dropping the corresponding
reference if it had been set. After that kill_litter_super() becomes
an equivalent of kill_anon_super().
Doing that in a single step is not feasible - it would affect too many places
in too many filesystems. It has to be split into a series.
This work has really started early in 2024; quite a few preliminary pieces
have already gone into mainline. This chunk is finally getting to the
meat of that stuff - infrastructure and most of the conversions to it.
Some pieces are still sitting in the local branches, but the bulk of
that stuff is here.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-persistency' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull persistent dentry infrastructure and conversion from Al Viro:
"Some filesystems use a kinda-sorta controlled dentry refcount leak to
pin dentries of created objects in dcache (and undo it when removing
those). A reference is grabbed and not released, but it's not actually
_stored_ anywhere.
That works, but it's hard to follow and verify; among other things, we
have no way to tell _which_ of the increments is intended to be an
unpaired one. Worse, on removal we need to decide whether the
reference had already been dropped, which can be non-trivial if that
removal is on umount and we need to figure out if this dentry is
pinned due to e.g. unlink() not done. Usually that is handled by using
kill_litter_super() as ->kill_sb(), but there are open-coded special
cases of the same (consider e.g. /proc/self).
Things get simpler if we introduce a new dentry flag
(DCACHE_PERSISTENT) marking those "leaked" dentries. Having it set
claims responsibility for +1 in refcount.
The end result this series is aiming for:
- get these unbalanced dget() and dput() replaced with new primitives
that would, in addition to adjusting refcount, set and clear
persistency flag.
- instead of having kill_litter_super() mess with removing the
remaining "leaked" references (e.g. for all tmpfs files that hadn't
been removed prior to umount), have the regular
shrink_dcache_for_umount() strip DCACHE_PERSISTENT of all dentries,
dropping the corresponding reference if it had been set. After that
kill_litter_super() becomes an equivalent of kill_anon_super().
Doing that in a single step is not feasible - it would affect too many
places in too many filesystems. It has to be split into a series.
This work has really started early in 2024; quite a few preliminary
pieces have already gone into mainline. This chunk is finally getting
to the meat of that stuff - infrastructure and most of the conversions
to it.
Some pieces are still sitting in the local branches, but the bulk of
that stuff is here"
* tag 'pull-persistency' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits)
d_make_discardable(): warn if given a non-persistent dentry
kill securityfs_recursive_remove()
convert securityfs
get rid of kill_litter_super()
convert rust_binderfs
convert nfsctl
convert rpc_pipefs
convert hypfs
hypfs: swich hypfs_create_u64() to returning int
hypfs: switch hypfs_create_str() to returning int
hypfs: don't pin dentries twice
convert gadgetfs
gadgetfs: switch to simple_remove_by_name()
convert functionfs
functionfs: switch to simple_remove_by_name()
functionfs: fix the open/removal races
functionfs: need to cancel ->reset_work in ->kill_sb()
functionfs: don't bother with ffs->ref in ffs_data_{opened,closed}()
functionfs: don't abuse ffs_data_closed() on fs shutdown
convert selinuxfs
...
- The 10 patch series "__vmalloc()/kvmalloc() and no-block support" from
Uladzislau Rezki reworks the vmalloc() code to support non-blocking
allocations (GFP_ATOIC, GFP_NOWAIT).
- The 2 patch series "ksm: fix exec/fork inheritance" from xu xin fixes
a rare case where the KSM MMF_VM_MERGE_ANY prctl state is not inherited
across fork/exec.
- The 4 patch series "mm/zswap: misc cleanup of code and documentations"
from SeongJae Park does some light maintenance work on the zswap code.
- The 5 patch series "mm/page_owner: add debugfs files 'show_handles'
and 'show_stacks_handles'" from Mauricio Faria de Oliveira enhances the
/sys/kernel/debug/page_owner debug feature. It adds unique identifiers
to differentiate the various stack traces so that userspace monitoring
tools can better match stack traces over time.
- The 2 patch series "mm/page_alloc: pcp->batch cleanups" from Joshua
Hahn makes some minor alterations to the page allocator's per-cpu-pages
feature.
- The 2 patch series "Improve UFFDIO_MOVE scalability by removing
anon_vma lock" from Lokesh Gidra addresses a scalability issue in
userfaultfd's UFFDIO_MOVE operation.
- The 2 patch series "kasan: cleanups for kasan_enabled() checks" from
Sabyrzhan Tasbolatov performs some cleanup in the KASAN code.
- The 2 patch series "drivers/base/node: fold node register and
unregister functions" from Donet Tom cleans up the NUMA node handling
code a little.
- The 4 patch series "mm: some optimizations for prot numa" from Kefeng
Wang provides some cleanups and small optimizations to the NUMA
allocation hinting code.
- The 5 patch series "mm/page_alloc: Batch callers of
free_pcppages_bulk" from Joshua Hahn addresses long lock hold times at
boot on large machines. These were causing (harmless) softlockup
warnings.
- The 2 patch series "optimize the logic for handling dirty file folios
during reclaim" from Baolin Wang removes some now-unnecessary work from
page reclaim.
- The 10 patch series "mm/damon: allow DAMOS auto-tuned for per-memcg
per-node memory usage" from SeongJae Park enhances the DAMOS auto-tuning
feature.
- The 2 patch series "mm/damon: fixes for address alignment issues in
DAMON_LRU_SORT and DAMON_RECLAIM" from Quanmin Yan fixes DAMON_LRU_SORT
and DAMON_RECLAIM with certain userspace configuration.
- The 15 patch series "expand mmap_prepare functionality, port more
users" from Lorenzo Stoakes enhances the new(ish)
file_operations.mmap_prepare() method and ports additional callsites
from the old ->mmap() over to ->mmap_prepare().
- The 8 patch series "Fix stale IOTLB entries for kernel address space"
from Lu Baolu fixes a bug (and possible security issue on non-x86) in
the IOMMU code. In some situations the IOMMU could be left hanging onto
a stale kernel pagetable entry.
- The 4 patch series "mm/huge_memory: cleanup __split_unmapped_folio()"
from Wei Yang cleans up and optimizes the folio splitting code.
- The 5 patch series "mm, swap: misc cleanup and bugfix" from Kairui
Song implements some cleanups and a minor fix in the swap discard code.
- The 8 patch series "mm/damon: misc documentation fixups" from SeongJae
Park does as advertised.
- The 9 patch series "mm/damon: support pin-point targets removal" from
SeongJae Park permits userspace to remove a specific monitoring target
in the middle of the current targets list.
- The 2 patch series "mm: MISC follow-up patches for linux/pgalloc.h"
from Harry Yoo implements a couple of cleanups related to mm header file
inclusion.
- The 2 patch series "mm/swapfile.c: select swap devices of default
priority round robin" from Baoquan He improves the selection of swap
devices for NUMA machines.
- The 3 patch series "mm: Convert memory block states (MEM_*) macros to
enums" from Israel Batista changes the memory block labels from macros
to enums so they will appear in kernel debug info.
- The 3 patch series "ksm: perform a range-walk to jump over holes in
break_ksm" from Pedro Demarchi Gomes addresses an inefficiency when KSM
unmerges an address range.
- The 22 patch series "mm/damon/tests: fix memory bugs in kunit tests"
from SeongJae Park fixes leaks and unhandled malloc() failures in DAMON
userspace unit tests.
- The 2 patch series "some cleanups for pageout()" from Baolin Wang
cleans up a couple of minor things in the page scanner's
writeback-for-eviction code.
- The 2 patch series "mm/hugetlb: refactor sysfs/sysctl interfaces" from
Hui Zhu moves hugetlb's sysfs/sysctl handling code into a new file.
- The 9 patch series "introduce VM_MAYBE_GUARD and make it sticky" from
Lorenzo Stoakes makes the VMA guard regions available in /proc/pid/smaps
and improves the mergeability of guarded VMAs.
- The 2 patch series "mm: perform guard region install/remove under VMA
lock" from Lorenzo Stoakes reduces mmap lock contention for callers
performing VMA guard region operations.
- The 2 patch series "vma_start_write_killable" from Matthew Wilcox
starts work in permitting applications to be killed when they are
waiting on a read_lock on the VMA lock.
- The 11 patch series "mm/damon/tests: add more tests for online
parameters commit" from SeongJae Park adds additional userspace testing
of DAMON's "commit" feature.
- The 9 patch series "mm/damon: misc cleanups" from SeongJae Park does
that.
- The 2 patch series "make VM_SOFTDIRTY a sticky VMA flag" from Lorenzo
Stoakes addresses the possible loss of a VMA's VM_SOFTDIRTY flag when
that VMA is merged with another.
- The 16 patch series "mm: support device-private THP" from Balbir Singh
introduces support for Transparent Huge Page (THP) migration in zone
device-private memory.
- The 3 patch series "Optimize folio split in memory failure" from Zi
Yan optimizes folio split operations in the memory failure code.
- The 2 patch series "mm/huge_memory: Define split_type and consolidate
split support checks" from Wei Yang provides some more cleanups in the
folio splitting code.
- The 16 patch series "mm: remove is_swap_[pte, pmd]() + non-swap
entries, introduce leaf entries" from Lorenzo Stoakes cleans up our
handling of pagetable leaf entries by introducing the concept of
'software leaf entries', of type softleaf_t.
- The 4 patch series "reparent the THP split queue" from Muchun Song
reparents the THP split queue to its parent memcg. This is in
preparation for addressing the long-standing "dying memcg" problem,
wherein dead memcg's linger for too long, consuming memory resources.
- The 3 patch series "unify PMD scan results and remove redundant
cleanup" from Wei Yang does a little cleanup in the hugepage collapse
code.
- The 6 patch series "zram: introduce writeback bio batching" from
Sergey Senozhatsky improves zram writeback efficiency by introducing
batched bio writeback support.
- The 4 patch series "memcg: cleanup the memcg stats interfaces" from
Shakeel Butt cleans up our handling of the interrupt safety of some
memcg stats.
- The 4 patch series "make vmalloc gfp flags usage more apparent" from
Vishal Moola cleans up vmalloc's handling of incoming GFP flags.
- The 6 patch series "mm: Add soft-dirty and uffd-wp support for RISC-V"
from Chunyan Zhang teches soft dirty and userfaultfd write protect
tracking to use RISC-V's Svrsw60t59b extension.
- The 5 patch series "mm: swap: small fixes and comment cleanups" from
Youngjun Park fixes a small bug and cleans up some of the swap code.
- The 4 patch series "initial work on making VMA flags a bitmap" from
Lorenzo Stoakes starts work on converting the vma struct's flags to a
bitmap, so we stop running out of them, especially on 32-bit.
- The 2 patch series "mm/swapfile: fix and cleanup swap list iterations"
from Youngjun Park addresses a possible bug in the swap discard code and
cleans things up a little.
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Merge tag 'mm-stable-2025-12-03-21-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"__vmalloc()/kvmalloc() and no-block support" (Uladzislau Rezki)
Rework the vmalloc() code to support non-blocking allocations
(GFP_ATOIC, GFP_NOWAIT)
"ksm: fix exec/fork inheritance" (xu xin)
Fix a rare case where the KSM MMF_VM_MERGE_ANY prctl state is not
inherited across fork/exec
"mm/zswap: misc cleanup of code and documentations" (SeongJae Park)
Some light maintenance work on the zswap code
"mm/page_owner: add debugfs files 'show_handles' and 'show_stacks_handles'" (Mauricio Faria de Oliveira)
Enhance the /sys/kernel/debug/page_owner debug feature by adding
unique identifiers to differentiate the various stack traces so
that userspace monitoring tools can better match stack traces over
time
"mm/page_alloc: pcp->batch cleanups" (Joshua Hahn)
Minor alterations to the page allocator's per-cpu-pages feature
"Improve UFFDIO_MOVE scalability by removing anon_vma lock" (Lokesh Gidra)
Address a scalability issue in userfaultfd's UFFDIO_MOVE operation
"kasan: cleanups for kasan_enabled() checks" (Sabyrzhan Tasbolatov)
"drivers/base/node: fold node register and unregister functions" (Donet Tom)
Clean up the NUMA node handling code a little
"mm: some optimizations for prot numa" (Kefeng Wang)
Cleanups and small optimizations to the NUMA allocation hinting
code
"mm/page_alloc: Batch callers of free_pcppages_bulk" (Joshua Hahn)
Address long lock hold times at boot on large machines. These were
causing (harmless) softlockup warnings
"optimize the logic for handling dirty file folios during reclaim" (Baolin Wang)
Remove some now-unnecessary work from page reclaim
"mm/damon: allow DAMOS auto-tuned for per-memcg per-node memory usage" (SeongJae Park)
Enhance the DAMOS auto-tuning feature
"mm/damon: fixes for address alignment issues in DAMON_LRU_SORT and DAMON_RECLAIM" (Quanmin Yan)
Fix DAMON_LRU_SORT and DAMON_RECLAIM with certain userspace
configuration
"expand mmap_prepare functionality, port more users" (Lorenzo Stoakes)
Enhance the new(ish) file_operations.mmap_prepare() method and port
additional callsites from the old ->mmap() over to ->mmap_prepare()
"Fix stale IOTLB entries for kernel address space" (Lu Baolu)
Fix a bug (and possible security issue on non-x86) in the IOMMU
code. In some situations the IOMMU could be left hanging onto a
stale kernel pagetable entry
"mm/huge_memory: cleanup __split_unmapped_folio()" (Wei Yang)
Clean up and optimize the folio splitting code
"mm, swap: misc cleanup and bugfix" (Kairui Song)
Some cleanups and a minor fix in the swap discard code
"mm/damon: misc documentation fixups" (SeongJae Park)
"mm/damon: support pin-point targets removal" (SeongJae Park)
Permit userspace to remove a specific monitoring target in the
middle of the current targets list
"mm: MISC follow-up patches for linux/pgalloc.h" (Harry Yoo)
A couple of cleanups related to mm header file inclusion
"mm/swapfile.c: select swap devices of default priority round robin" (Baoquan He)
improve the selection of swap devices for NUMA machines
"mm: Convert memory block states (MEM_*) macros to enums" (Israel Batista)
Change the memory block labels from macros to enums so they will
appear in kernel debug info
"ksm: perform a range-walk to jump over holes in break_ksm" (Pedro Demarchi Gomes)
Address an inefficiency when KSM unmerges an address range
"mm/damon/tests: fix memory bugs in kunit tests" (SeongJae Park)
Fix leaks and unhandled malloc() failures in DAMON userspace unit
tests
"some cleanups for pageout()" (Baolin Wang)
Clean up a couple of minor things in the page scanner's
writeback-for-eviction code
"mm/hugetlb: refactor sysfs/sysctl interfaces" (Hui Zhu)
Move hugetlb's sysfs/sysctl handling code into a new file
"introduce VM_MAYBE_GUARD and make it sticky" (Lorenzo Stoakes)
Make the VMA guard regions available in /proc/pid/smaps and
improves the mergeability of guarded VMAs
"mm: perform guard region install/remove under VMA lock" (Lorenzo Stoakes)
Reduce mmap lock contention for callers performing VMA guard region
operations
"vma_start_write_killable" (Matthew Wilcox)
Start work on permitting applications to be killed when they are
waiting on a read_lock on the VMA lock
"mm/damon/tests: add more tests for online parameters commit" (SeongJae Park)
Add additional userspace testing of DAMON's "commit" feature
"mm/damon: misc cleanups" (SeongJae Park)
"make VM_SOFTDIRTY a sticky VMA flag" (Lorenzo Stoakes)
Address the possible loss of a VMA's VM_SOFTDIRTY flag when that
VMA is merged with another
"mm: support device-private THP" (Balbir Singh)
Introduce support for Transparent Huge Page (THP) migration in zone
device-private memory
"Optimize folio split in memory failure" (Zi Yan)
"mm/huge_memory: Define split_type and consolidate split support checks" (Wei Yang)
Some more cleanups in the folio splitting code
"mm: remove is_swap_[pte, pmd]() + non-swap entries, introduce leaf entries" (Lorenzo Stoakes)
Clean up our handling of pagetable leaf entries by introducing the
concept of 'software leaf entries', of type softleaf_t
"reparent the THP split queue" (Muchun Song)
Reparent the THP split queue to its parent memcg. This is in
preparation for addressing the long-standing "dying memcg" problem,
wherein dead memcg's linger for too long, consuming memory
resources
"unify PMD scan results and remove redundant cleanup" (Wei Yang)
A little cleanup in the hugepage collapse code
"zram: introduce writeback bio batching" (Sergey Senozhatsky)
Improve zram writeback efficiency by introducing batched bio
writeback support
"memcg: cleanup the memcg stats interfaces" (Shakeel Butt)
Clean up our handling of the interrupt safety of some memcg stats
"make vmalloc gfp flags usage more apparent" (Vishal Moola)
Clean up vmalloc's handling of incoming GFP flags
"mm: Add soft-dirty and uffd-wp support for RISC-V" (Chunyan Zhang)
Teach soft dirty and userfaultfd write protect tracking to use
RISC-V's Svrsw60t59b extension
"mm: swap: small fixes and comment cleanups" (Youngjun Park)
Fix a small bug and clean up some of the swap code
"initial work on making VMA flags a bitmap" (Lorenzo Stoakes)
Start work on converting the vma struct's flags to a bitmap, so we
stop running out of them, especially on 32-bit
"mm/swapfile: fix and cleanup swap list iterations" (Youngjun Park)
Address a possible bug in the swap discard code and clean things
up a little
[ This merge also reverts commit ebb9aeb980 ("vfio/nvgrace-gpu:
register device memory for poison handling") because it looks
broken to me, I've asked for clarification - Linus ]
* tag 'mm-stable-2025-12-03-21-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
mm: fix vma_start_write_killable() signal handling
mm/swapfile: use plist_for_each_entry in __folio_throttle_swaprate
mm/swapfile: fix list iteration when next node is removed during discard
fs/proc/task_mmu.c: fix make_uffd_wp_huge_pte() huge pte handling
mm/kfence: add reboot notifier to disable KFENCE on shutdown
memcg: remove inc/dec_lruvec_kmem_state helpers
selftests/mm/uffd: initialize char variable to Null
mm: fix DEBUG_RODATA_TEST indentation in Kconfig
mm: introduce VMA flags bitmap type
tools/testing/vma: eliminate dependency on vma->__vm_flags
mm: simplify and rename mm flags function for clarity
mm: declare VMA flags by bit
zram: fix a spelling mistake
mm/page_alloc: optimize lowmem_reserve max lookup using its semantic monotonicity
mm/vmscan: skip increasing kswapd_failures when reclaim was boosted
pagemap: update BUDDY flag documentation
mm: swap: remove scan_swap_map_slots() references from comments
mm: swap: change swap_alloc_slow() to void
mm, swap: remove redundant comment for read_swap_cache_async
mm, swap: use SWP_SOLIDSTATE to determine if swap is rotational
...
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Merge tag 'vfs-6.19-rc1.autofs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull autofs update from Christian Brauner:
"Prevent futile mount triggers in private mount namespaces.
Fix a problematic loop in autofs when a mount namespace contains
autofs mounts that are propagation private and there is no
namespace-specific automount daemon to handle possible automounting.
Previously, attempted path resolution would loop until MAXSYMLINKS was
reached before failing, causing significant noise in the log.
The fix adds a check in autofs ->d_automount() so that the VFS can
immediately return EPERM in this case. Since the mount is propagation
private, EPERM is the most appropriate error code"
* tag 'vfs-6.19-rc1.autofs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
autofs: dont trigger mount if it cant succeed
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Merge tag 'vfs-6.19-rc1.directory.locking' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull directory locking updates from Christian Brauner:
"This contains the work to add centralized APIs for directory locking
operations.
This series is part of a larger effort to change directory operation
locking to allow multiple concurrent operations in a directory. The
ultimate goal is to lock the target dentry(s) rather than the whole
parent directory.
To help with changing the locking protocol, this series centralizes
locking and lookup in new helper functions. The helpers establish a
pattern where it is the dentry that is being locked and unlocked
(currently the lock is held on dentry->d_parent->d_inode, but that can
change in the future).
This also changes vfs_mkdir() to unlock the parent on failure, as well
as dput()ing the dentry. This allows end_creating() to only require
the target dentry (which may be IS_ERR() after vfs_mkdir()), not the
parent"
* tag 'vfs-6.19-rc1.directory.locking' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
nfsd: fix end_creating() conversion
VFS: introduce end_creating_keep()
VFS: change vfs_mkdir() to unlock on failure.
ecryptfs: use new start_creating/start_removing APIs
Add start_renaming_two_dentries()
VFS/ovl/smb: introduce start_renaming_dentry()
VFS/nfsd/ovl: introduce start_renaming() and end_renaming()
VFS: add start_creating_killable() and start_removing_killable()
VFS: introduce start_removing_dentry()
smb/server: use end_removing_noperm for for target of smb2_create_link()
VFS: introduce start_creating_noperm() and start_removing_noperm()
VFS/nfsd/cachefiles/ovl: introduce start_removing() and end_removing()
VFS/nfsd/cachefiles/ovl: add start_creating() and end_creating()
VFS: tidy up do_unlinkat()
VFS: introduce start_dirop() and end_dirop()
debugfs: rename end_creating() to debugfs_end_creating()
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Merge tag 'vfs-6.19-rc1.directory.delegations' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull directory delegations update from Christian Brauner:
"This contains the work for recall-only directory delegations for
knfsd.
Add support for simple, recallable-only directory delegations. This
was decided at the fall NFS Bakeathon where the NFS client and server
maintainers discussed how to merge directory delegation support.
The approach starts with recallable-only delegations for several reasons:
1. RFC8881 has gaps that are being addressed in RFC8881bis. In
particular, it requires directory position information for
CB_NOTIFY callbacks, which is difficult to implement properly
under Linux. The spec is being extended to allow that information
to be omitted.
2. Client-side support for CB_NOTIFY still lags. The client side
involves heuristics about when to request a delegation.
3. Early indication shows simple, recallable-only delegations can
help performance. Anna Schumaker mentioned seeing a multi-minute
speedup in xfstests runs with them enabled.
With these changes, userspace can also request a read lease on a
directory that will be recalled on conflicting accesses. This may be
useful for applications like Samba. Users can disable leases
altogether via the fs.leases-enable sysctl if needed.
VFS changes:
- Dedicated Type for Delegations
Introduce struct delegated_inode to track inodes that may have
delegations that need to be broken. This replaces the previous
approach of passing raw inode pointers through the delegation
breaking code paths, providing better type safety and clearer
semantics for the delegation machinery.
- Break parent directory delegations in open(..., O_CREAT) codepath
- Allow mkdir to wait for delegation break on parent
- Allow rmdir to wait for delegation break on parent
- Add try_break_deleg calls for parents to vfs_link(), vfs_rename(),
and vfs_unlink()
- Make vfs_create(), vfs_mknod(), and vfs_symlink() break delegations
on parent directory
- Clean up argument list for vfs_create()
- Expose delegation support to userland
Filelock changes:
- Make lease_alloc() take a flags argument
- Rework the __break_lease API to use flags
- Add struct delegated_inode
- Push the S_ISREG check down to ->setlease handlers
- Lift the ban on directory leases in generic_setlease
NFSD changes:
- Allow filecache to hold S_IFDIR files
- Allow DELEGRETURN on directories
- Wire up GET_DIR_DELEGATION handling
Fixes:
- Fix kernel-doc warnings in __fcntl_getlease
- Add needed headers for new struct delegation definition"
* tag 'vfs-6.19-rc1.directory.delegations' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
vfs: add needed headers for new struct delegation definition
filelock: __fcntl_getlease: fix kernel-doc warnings
vfs: expose delegation support to userland
nfsd: wire up GET_DIR_DELEGATION handling
nfsd: allow DELEGRETURN on directories
nfsd: allow filecache to hold S_IFDIR files
filelock: lift the ban on directory leases in generic_setlease
vfs: make vfs_symlink break delegations on parent dir
vfs: make vfs_mknod break delegations on parent directory
vfs: make vfs_create break delegations on parent directory
vfs: clean up argument list for vfs_create()
vfs: break parent dir delegations in open(..., O_CREAT) codepath
vfs: allow rmdir to wait for delegation break on parent
vfs: allow mkdir to wait for delegation break on parent
vfs: add try_break_deleg calls for parents to vfs_{link,rename,unlink}
filelock: push the S_ISREG check down to ->setlease handlers
filelock: add struct delegated_inode
filelock: rework the __break_lease API to use flags
filelock: make lease_alloc() take a flags argument
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Merge tag 'vfs-6.19-rc1.fs_header' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull fs header updates from Christian Brauner:
"This contains initial work to start splitting up fs.h.
Begin the long-overdue work of splitting up the monolithic fs.h
header. The header has grown to over 3000 lines and includes types and
functions for many different subsystems, making it difficult to
navigate and causing excessive compilation dependencies.
This series introduces new focused headers for superblock-related
code:
- Rename fs_types.h to fs_dirent.h to better reflect its actual
content (directory entry types)
- Add fs/super_types.h containing superblock type definitions
- Add fs/super.h containing superblock function declarations
This is the first step in a longer effort to modularize the VFS
headers.
Cleanups:
- Inode Field Layout Optimization (Mateusz Guzik)
Move inode fields used during fast path lookup closer together to
improve cache locality during path resolution.
- current_umask() Optimization (Mateusz Guzik)
Inline current_umask() and move it to fs_struct.h. This improves
performance by avoiding function call overhead for this
frequently-used function, and places it in a more appropriate
header since it operates on fs_struct"
* tag 'vfs-6.19-rc1.fs_header' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: move inode fields used during fast path lookup closer together
fs: inline current_umask() and move it to fs_struct.h
fs: add fs/super.h header
fs: add fs/super_types.h header
fs: rename fs_types.h to fs_dirent.h
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Merge tag 'vfs-6.19-rc1.writeback' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull writeback updates from Christian Brauner:
"Features:
- Allow file systems to increase the minimum writeback chunk size.
The relatively low minimal writeback size of 4MiB means that
written back inodes on rotational media are switched a lot. Besides
introducing additional seeks, this also can lead to extreme file
fragmentation on zoned devices when a lot of files are cached
relative to the available writeback bandwidth.
This adds a superblock field that allows the file system to
override the default size, and sets it to the zone size for zoned
XFS.
- Add logging for slow writeback when it exceeds
sysctl_hung_task_timeout_secs. This helps identify tasks waiting
for a long time and pinpoint potential issues. Recording the
starting jiffies is also useful when debugging a crashed vmcore.
- Wake up waiting tasks when finishing the writeback of a chunk
Cleanups:
- filemap_* writeback interface cleanups.
Adding filemap_fdatawrite_wbc ended up being a mistake, as all but
the original btrfs caller should be using better high level
interfaces instead.
This series removes all these low-level interfaces, switches btrfs
to a more specific interface, and cleans up other too low-level
interfaces. With this the writeback_control that is passed to the
writeback code is only initialized in three places.
- Remove __filemap_fdatawrite, __filemap_fdatawrite_range, and
filemap_fdatawrite_wbc
- Add filemap_flush_nr helper for btrfs
- Push struct writeback_control into start_delalloc_inodes in btrfs
- Rename filemap_fdatawrite_range_kick to filemap_flush_range
- Stop opencoding filemap_fdatawrite_range in 9p, ocfs2, and mm
- Make wbc_to_tag() inline and use it in fs"
* tag 'vfs-6.19-rc1.writeback' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: Make wbc_to_tag() inline and use it in fs.
xfs: set s_min_writeback_pages for zoned file systems
writeback: allow the file system to override MIN_WRITEBACK_PAGES
writeback: cleanup writeback_chunk_size
mm: rename filemap_fdatawrite_range_kick to filemap_flush_range
mm: remove __filemap_fdatawrite_range
mm: remove filemap_fdatawrite_wbc
mm: remove __filemap_fdatawrite
mm,btrfs: add a filemap_flush_nr helper
btrfs: push struct writeback_control into start_delalloc_inodes
btrfs: use the local tmp_inode variable in start_delalloc_inodes
ocfs2: don't opencode filemap_fdatawrite_range in ocfs2_journal_submit_inode_data_buffers
9p: don't opencode filemap_fdatawrite_range in v9fs_mmap_vm_close
mm: don't opencode filemap_fdatawrite_range in filemap_invalidate_inode
writeback: Add logging for slow writeback (exceeds sysctl_hung_task_timeout_secs)
writeback: Wake up waiting tasks when finishing the writeback of a chunk.
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Merge tag 'vfs-6.19-rc1.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs inode updates from Christian Brauner:
"Features:
- Hide inode->i_state behind accessors. Open-coded accesses prevent
asserting they are done correctly. One obvious aspect is locking,
but significantly more can be checked. For example it can be
detected when the code is clearing flags which are already missing,
or is setting flags when it is illegal (e.g., I_FREEING when
->i_count > 0)
- Provide accessors for ->i_state, converts all filesystems using
coccinelle and manual conversions (btrfs, ceph, smb, f2fs, gfs2,
overlayfs, nilfs2, xfs), and makes plain ->i_state access fail to
compile
- Rework I_NEW handling to operate without fences, simplifying the
code after the accessor infrastructure is in place
Cleanups:
- Move wait_on_inode() from writeback.h to fs.h
- Spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb
for clarity
- Cosmetic fixes to LRU handling
- Push list presence check into inode_io_list_del()
- Touch up predicts in __d_lookup_rcu()
- ocfs2: retire ocfs2_drop_inode() and I_WILL_FREE usage
- Assert on ->i_count in iput_final()
- Assert ->i_lock held in __iget()
Fixes:
- Add missing fences to I_NEW handling"
* tag 'vfs-6.19-rc1.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (22 commits)
dcache: touch up predicts in __d_lookup_rcu()
fs: push list presence check into inode_io_list_del()
fs: cosmetic fixes to lru handling
fs: rework I_NEW handling to operate without fences
fs: make plain ->i_state access fail to compile
xfs: use the new ->i_state accessors
nilfs2: use the new ->i_state accessors
overlayfs: use the new ->i_state accessors
gfs2: use the new ->i_state accessors
f2fs: use the new ->i_state accessors
smb: use the new ->i_state accessors
ceph: use the new ->i_state accessors
btrfs: use the new ->i_state accessors
Manual conversion to use ->i_state accessors of all places not covered by coccinelle
Coccinelle-based conversion to use ->i_state accessors
fs: provide accessors for ->i_state
fs: spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb
fs: move wait_on_inode() from writeback.h to fs.h
fs: add missing fences to I_NEW handling
ocfs2: retire ocfs2_drop_inode() and I_WILL_FREE usage
...
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Merge tag 'vfs-6.19-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"Features:
- Cheaper MAY_EXEC handling for path lookup. This elides MAY_WRITE
permission checks during path lookup and adds the
IOP_FASTPERM_MAY_EXEC flag so filesystems like btrfs can avoid
expensive permission work.
- Hide dentry_cache behind runtime const machinery.
- Add German Maglione as virtiofs co-maintainer.
Cleanups:
- Tidy up and inline step_into() and walk_component() for improved
code generation.
- Re-enable IOCB_NOWAIT writes to files. This refactors file
timestamp update logic, fixing a layering bypass in btrfs when
updating timestamps on device files and improving FMODE_NOCMTIME
handling in VFS now that nfsd started using it.
- Path lookup optimizations extracting slowpaths into dedicated
routines and adding branch prediction hints for mntput_no_expire(),
fd_install(), lookup_slow(), and various other hot paths.
- Enable clang's -fms-extensions flag, requiring a JFS rename to
avoid conflicts.
- Remove spurious exports in fs/file_attr.c.
- Stop duplicating union pipe_index declaration. This depends on the
shared kbuild branch that brings in -fms-extensions support which
is merged into this branch.
- Use MD5 library instead of crypto_shash in ecryptfs.
- Use largest_zero_folio() in iomap_dio_zero().
- Replace simple_strtol/strtoul with kstrtoint/kstrtouint in init and
initrd code.
- Various typo fixes.
Fixes:
- Fix emergency sync for btrfs. Btrfs requires an explicit sync_fs()
call with wait == 1 to commit super blocks. The emergency sync path
never passed this, leaving btrfs data uncommitted during emergency
sync.
- Use local kmap in watch_queue's post_one_notification().
- Add hint prints in sb_set_blocksize() for LBS dependency on THP"
* tag 'vfs-6.19-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits)
MAINTAINERS: add German Maglione as virtiofs co-maintainer
fs: inline step_into() and walk_component()
fs: tidy up step_into() & friends before inlining
orangefs: use inode_update_timestamps directly
btrfs: fix the comment on btrfs_update_time
btrfs: use vfs_utimes to update file timestamps
fs: export vfs_utimes
fs: lift the FMODE_NOCMTIME check into file_update_time_flags
fs: refactor file timestamp update logic
include/linux/fs.h: trivial fix: regualr -> regular
fs/splice.c: trivial fix: pipes -> pipe's
fs: mark lookup_slow() as noinline
fs: add predicts based on nd->depth
fs: move mntput_no_expire() slowpath into a dedicated routine
fs: remove spurious exports in fs/file_attr.c
watch_queue: Use local kmap in post_one_notification()
fs: touch up predicts in path lookup
fs: move fd_install() slowpath into a dedicated routine and provide commentary
fs: hide dentry_cache behind runtime const machinery
fs: touch predicts in do_dentry_open()
...
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Merge tag 'vfs-6.19-rc1.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull iomap updates from Christian Brauner:
"FUSE iomap Support for Buffered Reads:
This adds iomap support for FUSE buffered reads and readahead. This
enables granular uptodate tracking with large folios so only
non-uptodate portions need to be read. Also fixes a race condition
with large folios + writeback cache that could cause data corruption
on partial writes followed by reads.
- Refactored iomap read/readahead bio logic into helpers
- Added caller-provided callbacks for read operations
- Moved buffered IO bio logic into new file
- FUSE now uses iomap for read_folio and readahead
Zero Range Folio Batch Support:
Add folio batch support for iomap_zero_range() to handle dirty
folios over unwritten mappings. Fix raciness issues where dirty data
could be lost during zero range operations.
- filemap_get_folios_tag_range() helper for dirty folio lookup
- Optional zero range dirty folio processing
- XFS fills dirty folios on zero range of unwritten mappings
- Removed old partial EOF zeroing optimization
DIO Write Completions from Interrupt Context:
Restore pre-iomap behavior where pure overwrite completions run
inline rather than being deferred to workqueue. Reduces context
switches for high-performance workloads like ScyllaDB.
- Removed unused IOCB_DIO_CALLER_COMP code
- Error completions always run in user context (fixes zonefs)
- Reworked REQ_FUA selection logic
- Inverted IOMAP_DIO_INLINE_COMP to IOMAP_DIO_OFFLOAD_COMP
Buffered IO Cleanups:
Some performance and code clarity improvements:
- Replace manual bitmap scanning with find_next_bit()
- Simplify read skip logic for writes
- Optimize pending async writeback accounting
- Better variable naming
- Documentation for iomap_finish_folio_write() requirements
Misaligned Vectors for Zoned XFS:
Enables sub-block aligned vectors in XFS always-COW mode for zoned
devices via new IOMAP_DIO_FSBLOCK_ALIGNED flag.
Bug Fixes:
- Allocate s_dio_done_wq for async reads (fixes syzbot report after
error completion changes)
- Fix iomap_read_end() for already uptodate folios (regression fix)"
* tag 'vfs-6.19-rc1.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (40 commits)
iomap: allocate s_dio_done_wq for async reads as well
iomap: fix iomap_read_end() for already uptodate folios
iomap: invert the polarity of IOMAP_DIO_INLINE_COMP
iomap: support write completions from interrupt context
iomap: rework REQ_FUA selection
iomap: always run error completions in user context
fs, iomap: remove IOCB_DIO_CALLER_COMP
iomap: use find_next_bit() for uptodate bitmap scanning
iomap: use find_next_bit() for dirty bitmap scanning
iomap: simplify when reads can be skipped for writes
iomap: simplify ->read_folio_range() error handling for reads
iomap: optimize pending async writeback accounting
docs: document iomap writeback's iomap_finish_folio_write() requirement
iomap: account for unaligned end offsets when truncating read range
iomap: rename bytes_pending/bytes_accounted to bytes_submitted/bytes_not_submitted
xfs: support sub-block aligned vectors in always COW mode
iomap: add IOMAP_DIO_FSBLOCK_ALIGNED flag
xfs: error tag to force zeroing on debug kernels
iomap: remove old partial eof zeroing optimization
xfs: fill dirty folios on zero range of unwritten mappings
...
1. inode_bit_waitqueue() was somehow placed between __inode_add_lru() and
inode_add_lru(). move it up
2. assert ->i_lock is held in __inode_add_lru instead of just claiming it is
needed
3. s/__inode_add_lru/__inode_lru_list_add/ for consistency with itself
(inode_lru_list_del()) and similar routines for sb and io list
management
4. push list presence check into inode_lru_list_del(), just like sb and
io list
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251029131428.654761-2-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
In the inode hash code grab the state while ->i_lock is held. If found
to be set, synchronize the sleep once more with the lock held.
In the real world the flag is not set most of the time.
Apart from being simpler to reason about, it comes with a minor speed up
as now clearing the flag does not require the smp_mb() fence.
While here rename wait_on_inode() to wait_on_new_inode() to line it up
with __wait_on_freeing_inode().
Christian Brauner <brauner@kernel.org> says:
As per the discussion in [1] I folded in the diff sent in [2].
Link: https://lore.kernel.org/69238e4d.a70a0220.d98e3.006e.GAE@google.com [1]
Link: https://lore.kernel.org/c2kpawomkbvtahjm7y5mposbhckb7wxthi3iqy5yr22ggpucrm@ufvxwy233qxo [2]
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251010221737.1403539-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This was added by commit 099ada2c87 ("io_uring/rw: add write support
for IOCB_DIO_CALLER_COMP") and disabled a little later by commit
838b35bb6a ("io_uring/rw: disable IOCB_DIO_CALLER_COMP") because it
didn't work. Remove all the related code that sat unused for 2 years.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20251113170633.1453259-2-hch@lst.de
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
If a mount namespace contains autofs mounts, and they are propagation
private, and there is no namespace specific automount daemon to handle
possible automounting then attempted path resolution will loop until
MAXSYMLINKS is reached before failing causing quite a bit of noise in
the log.
Add a check for this in autofs ->d_automount() so that the VFS can
immediately return an error in this case. Since the mount is propagation
private an EPERM return seems most appropriate.
Suggested by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://patch.msgid.link/20251118024631.10854-2-raven@themaw.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
At this point there are very few call chains that might lead to
d_make_discardable() on a dentry that hadn't been made persistent:
calls of simple_unlink() and simple_rmdir() in configfs and
apparmorfs.
Both filesystems do pin (part of) their contents in dcache, but
they are currently playing very unusual games with that. Converting
them to more usual patterns might be possible, but it's definitely
going to be a long series of changes in both cases.
For now the easiest solution is to have both stop using simple_unlink()
and simple_rmdir() - that allows to make d_make_discardable() warn
when given a non-persistent dentry.
Rather than giving them full-blown private copies (with calls of
d_make_discardable() replaced with dput()), let's pull the parts of
simple_unlink() and simple_rmdir() that deal with timestamps and link
counts into separate helpers (__simple_unlink() and __simple_rmdir()
resp.) and have those used by configfs and apparmorfs.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Some drivers/filesystems need to perform additional tasks after the VMA is
set up. This is typically in the form of pre-population.
The forms of pre-population most likely to be performed are a PFN remap
or the insertion of normal folios and PFNs into a mixed map.
We start by implementing the PFN remap functionality, ensuring that we
perform the appropriate actions at the appropriate time - that is setting
flags at the point of .mmap_prepare, and performing the actual remap at the
point at which the VMA is fully established.
This prevents the driver from doing anything too crazy with a VMA at any
stage, and we retain complete control over how the mm functionality is
applied.
Unfortunately callers still do often require some kind of custom action,
so we add an optional success/error _hook to allow the caller to do
something after the action has succeeded or failed.
This is done at the point when the VMA has already been established, so
the harm that can be done is limited.
The error hook can be used to filter errors if necessary.
There may be cases in which the caller absolutely must hold the file rmap
lock until the operation is entirely complete. It is an edge case, but
certainly the hugetlbfs mmap hook requires it.
To accommodate this, we add the hide_from_rmap_until_complete flag to the
mmap_action type. In this case, if a new VMA is allocated, we will hold the
file rmap lock until the operation is entirely completed (including any
success/error hooks).
Note that we do not need to update __compat_vma_mmap() to accommodate this
flag, as this function will be invoked from an .mmap handler whose VMA is
not yet visible, so we implicitly hide it from the rmap.
If any error arises on these final actions, we simply unmap the VMA
altogether.
Also update the stacked filesystem compatibility layer to utilise the
action behaviour, and update the VMA tests accordingly.
While we're here, rename __compat_vma_mmap_prepare() to __compat_vma_mmap()
as we are now performing actions invoked by the mmap_prepare in addition to
just the mmap_prepare hook.
Link: https://lkml.kernel.org/r/2601199a7b2eaeadfcd8ab6e199c6d1706650c94.1760959442.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chatre, Reinette <reinette.chatre@intel.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Dave Martin <dave.martin@arm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Morse <james.morse@arm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Robin Murohy <robin.murphy@arm.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
simple_recursive_removal(), but instead of victim dentry it takes
parent + name.
Used to be open-coded in fs/fuse/control.c, but there's no need to expose
the guts of that thing there and there are other potential users, so
let's lift it into libfs...
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The fact that directory operations (create,remove,rename) are protected
by a lock on the parent is known widely throughout the kernel.
In order to change this - to instead lock the target dentry - it is
best to centralise this knowledge so it can be changed in one place.
This patch introduces start_dirop() which is local to VFS code.
It performs the required locking for create and remove. Rename
will be handled separately.
Various functions with names like start_creating() or start_removing_path(),
some of which already exist, will export this functionality beyond the VFS.
end_dirop() is the partner of start_dirop(). It drops the lock and
releases the reference on the dentry.
It *is* exported so that various end_creating etc functions can be inline.
As vfs_mkdir() drops the dentry on error we cannot use end_dirop() as
that won't unlock when the dentry IS_ERR(). For now we need an explicit
unlock when dentry IS_ERR(). I hope to change vfs_mkdir() to unlock
when it drops a dentry so that explicit unlock can go away.
end_dirop() can always be called on the result of start_dirop(), but not
after vfs_mkdir(). After a vfs_mkdir() we still may need the explicit
unlock as seen in end_creating_path().
As well as adding start_dirop() and end_dirop()
this patch uses them in:
- simple_start_creating (which requires sharing lookup_noperm_common()
with libfs.c)
- start_removing_path / start_removing_user_path_at
- filename_create / end_creating_path()
- do_rmdir(), do_unlinkat()
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-3-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
The generic inode_permission() routine does work which is known to be of
no significance for lookup. There are checks for MAY_WRITE, while the
requested permission is MAY_EXEC. Additionally devcgroup_inode_permission()
is called to check for devices, but it is an invariant the inode is a
directory.
Absent a ->permission func, execution lands in generic_permission()
which checks upfront if the requested permission is granted for
everyone.
We can elide the branches which are guaranteed to be false and cut
straight to the check if everyone happens to be allowed MAY_EXEC on the
inode (which holds true most of the time).
Moreover, filesystems which provide their own ->permission routine can
take advantage of the optimization by setting the IOP_FASTPERM_MAY_EXEC
flag on their inodes, which they can legitimately do if their MAY_EXEC
handling matches generic_permission().
As a simple benchmark, as part of compilation gcc issues access(2) on
numerous long paths, for example /usr/lib/gcc/x86_64-linux-gnu/12/crtendS.o
Issuing access(2) on it in a loop on ext4 on Sapphire Rapids (ops/s):
before: 3797556
after: 3987789 (+5%)
Note: this depends on the not-yet-landed ext4 patch to mark inodes with
cache_no_acl()
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251107142149.989998-2-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
In order to add directory delegation support, we must break delegations
on the parent on any change to the directory.
Add a delegated_inode parameter to vfs_symlink() and have it break the
delegation. do_symlinkat() can then wait on the delegation break before
proceeding.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-12-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
In order to add directory delegation support, we need to break
delegations on the parent whenever there is going to be a change in the
directory.
Add a new delegated_inode pointer to vfs_mknod() and have the
appropriate callers wait when there is an outstanding delegation. All
other callers just set the pointer to NULL.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-11-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
In order to add directory delegation support, we need to break
delegations on the parent whenever there is going to be a change in the
directory.
Add a delegated_inode parameter to vfs_create. Most callers are
converted to pass in NULL, but do_mknodat() is changed to wait for a
delegation break if there is one.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-10-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
As Neil points out:
"I would be in favour of dropping the "dir" arg because it is always
d_inode(dentry->d_parent) which is stable."
...and...
"Also *every* caller of vfs_create() passes ".excl = true". So maybe we
don't need that arg at all."
Drop both arguments from vfs_create() and fix up the callers.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-9-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
In order to add directory delegation support, we need to break
delegations on the parent whenever there is going to be a change in the
directory.
Add a delegated_inode struct to vfs_rmdir() and populate that
pointer with the parent inode if it's non-NULL. Most existing in-kernel
callers pass in a NULL pointer.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-7-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
In order to add directory delegation support, we need to break
delegations on the parent whenever there is going to be a change in the
directory.
Add a new delegated_inode parameter to vfs_mkdir. All of the existing
callers set that to NULL for now, except for do_mkdirat which will
properly block until the lease is gone.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-6-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
The current API requires a pointer to an inode pointer. It's easy for
callers to get this wrong. Add a new delegated_inode structure and use
that to pass back any inode that needs to be waited on.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20251111-dir-deleg-ro-v6-3-52f3feebb2f2@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This should avoid *some* cache misses.
Successful path lookup is guaranteed to load at least ->i_mode,
->i_opflags and ->i_acl. At the same time the common case will avoid
looking at more fields.
struct inode is not guaranteed to have any particular alignment, notably
ext4 has it only aligned to 8 bytes meaning nearby fields might happen
to be on the same or only adjacent cache lines depending on luck (or no
luck).
According to pahole:
umode_t i_mode; /* 0 2 */
short unsigned int i_opflags; /* 2 2 */
kuid_t i_uid; /* 4 4 */
kgid_t i_gid; /* 8 4 */
unsigned int i_flags; /* 12 4 */
struct posix_acl * i_acl; /* 16 8 */
struct posix_acl * i_default_acl; /* 24 8 */
->i_acl is unnecessarily separated by 8 bytes from the other fields.
With struct inode being offset 48 bytes into the cacheline this means an
avoidable miss. Note it will still be there for the 56 byte case.
New layout:
umode_t i_mode; /* 0 2 */
short unsigned int i_opflags; /* 2 2 */
unsigned int i_flags; /* 4 4 */
struct posix_acl * i_acl; /* 8 8 */
struct posix_acl * i_default_acl; /* 16 8 */
kuid_t i_uid; /* 24 4 */
kgid_t i_gid; /* 28 4 */
I verified with pahole there are no size or hole changes.
This is stopgap until someone(tm) sanitizes the layout in the first
place, allocation methods aside.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251109121931.1285366-1-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
There is no good reason to have this as a func call, other than avoiding
the churn of adding fs_struct.h as needed.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251104170448.630414-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
When sb_min_blocksize() returns 0 and the return value is not checked,
it may lead to a situation where sb->s_blocksize is 0 when
accessing the filesystem super block. After commit a64e5a5960
("bdev: add back PAGE_SIZE block size validation for
sb_set_blocksize()"), this becomes more likely to happen when the
block device’s logical_block_size is larger than PAGE_SIZE and the
filesystem is unformatted. Add the __must_check attribute to ensure
callers always check the return value.
Cc: stable@vger.kernel.org # v6.15
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Yongpeng Yang <yangyongpeng@xiaomi.com>
Link: https://patch.msgid.link/20251104125009.2111925-6-yangyongpeng.storage@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
The relatively low minimal writeback size of 4MiB means that written back
inodes on rotational media are switched a lot. Besides introducing
additional seeks, this also can lead to extreme file fragmentation on
zoned devices when a lot of files are cached relative to the available
writeback bandwidth.
Add a superblock field that allows the file system to override the
default size.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20251017034611.651385-3-hch@lst.de
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Rename filemap_fdatawrite_range_kick to filemap_flush_range because it
is the ranged version of filemap_flush.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20251024080431.324236-11-hch@lst.de
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
... to make sure all accesses are properly validated.
Merely renaming the var to __i_state still lets the compiler make the
following suggestion:
error: 'struct inode' has no member named 'i_state'; did you mean '__i_state'?
Unfortunately some people will add the __'s and call it a day.
In order to make it harder to mess up in this way, hide it behind a
struct. The resulting error message should be convincing in terms of
checking what to do:
error: invalid operands to binary & (have 'struct inode_state_flags' and 'int')
Of course people determined to do a plain access can still do it, but
nothing can be done for that case.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Open-coded accesses prevent asserting they are done correctly. One
obvious aspect is locking, but significantly more can checked. For
example it can be detected when the code is clearing flags which are
already missing, or is setting flags when it is illegal (e.g., I_FREEING
when ->i_count > 0).
In order to keep things manageable this patchset merely gets the thing
off the ground with only lockdep checks baked in.
Current consumers can be trivially converted.
Suppose flags I_A and I_B are to be handled.
If ->i_lock is held, then:
state = inode->i_state => state = inode_state_read(inode)
inode->i_state |= (I_A | I_B) => inode_state_set(inode, I_A | I_B)
inode->i_state &= ~(I_A | I_B) => inode_state_clear(inode, I_A | I_B)
inode->i_state = I_A | I_B => inode_state_assign(inode, I_A | I_B)
If ->i_lock is not held or only held conditionally:
state = inode->i_state => state = inode_state_read_once(inode)
inode->i_state |= (I_A | I_B) => inode_state_set_raw(inode, I_A | I_B)
inode->i_state &= ~(I_A | I_B) => inode_state_clear_raw(inode, I_A | I_B)
inode->i_state = I_A | I_B => inode_state_assign_raw(inode, I_A | I_B)
The "_once" vs "_raw" discrepancy stems from the read variant differing
by READ_ONCE as opposed to just lockdep checks.
Finally, if you want to atomically clear flags and set new ones, the
following:
state = inode->i_state;
state &= ~I_A;
state |= I_B;
inode->i_state = state;
turns into:
inode_state_replace(inode, I_A, I_B);
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
The only consumer outside of fs/inode.c is gfs2 and it already includes
fs.h in the relevant file.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Al Viro