[GIT PULL 15/16 for v7.2] vfs misc
From: Christian Brauner
Date: Fri Jun 12 2026 - 11:16:12 EST
Hey Linus,
/* Summary */
Features
- Reduce pipe->mutex contention by pre-allocating pages outside the
lock in anon_pipe_write().
anon_pipe_write() called alloc_page() once per page while holding
pipe->mutex. The allocation can sleep doing direct reclaim and runs
memcg charging, which extends the critical section and stalls any
concurrent reader on the same mutex. Now up to 8 pages are
pre-allocated before the mutex is taken, leftovers are recycled into
the per-pipe tmp_page[] cache before unlock, and any remainder is
released after unlock, keeping the allocator out of the critical
section on both sides. On a writers x readers sweep with 64KB writes
against a 1 MB pipe throughput improves 6-28% and average write
latency drops 5-22%; under memory pressure - when the cost of
holding the mutex across reclaim is highest - throughput improves
21-48% and latency drops 17-33%. The microbenchmark is added to
selftests.
- uaccess/sockptr: fix the ignored_trailing logic in
copy_struct_to_user() to behave as documented and the usize check in
copy_struct_from_sockptr() for user pointers, and add
copy_struct_{from,to}_bounce_buffer() and copy_struct_to_sockptr()
helpers for upcoming users (IPPROTO_SMBDIRECT, IPPROTO_QUIC).
- bpf: add a sleepable bpf_real_inode() kfunc that resolves the real
inode backing a dentry via d_real_inode(). On overlayfs the inode
attached to the dentry doesn't carry the underlying device
information; this is used by the filesystem restriction BPF program
that was merged into systemd.
- docs: add guidelines for submitting new filesystems, motivated by
the maintenance burden abandoned and untestable filesystems impose
on VFS developers, blocking infrastructure work like folio
conversions and iomap migration.
Fixes
- libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo()
and drop the now-redundant assignments in callers. This began as a
one-line dma-buf fix for a path_noexec() warning; a pseudo
filesystem has no reason not to set SB_I_NOEXEC. All init_pseudo()
callers were audited: the only visible effect is on dma-buf where
SB_I_NOEXEC silences the warning.
- Handle set_blocksize() failures in legacy filesystems (bfs, hpfs,
qnx4, jfs, befs, affs, isofs, minix, ntfs3, omfs). Mounting a device
with a sector size > PAGE_SIZE crashed roughly half of them; the
rest had the same missing error handling pattern. Plus a follow-up
releasing the superblock buffer_head when setting the minix v3 block
size fails.
- mount: honour SB_NOUSER in the new mount API.
- fs/fcntl: fix a SOFTIRQ-unsafe lock order in fasync signaling by
switching the process-group paths of send_sigio() and send_sigurg()
from read_lock(&tasklist_lock) to RCU, matching the single-PID path.
- vfs: add an FS_USERNS_DELEGATABLE flag and set it for NFS, fixing
delegated NFS mounts (fsopen() in a container with the mount
performed by a privileged daemon) that broke when non-init s_user_ns
was tied to FS_USERNS_MOUNT.
- selftests/namespaces: fix a hang in nsid_test where an unreaped
grandchild kept the TAP pipe write-end open, a waitpid(-1) race in
listns_efault_test, and a false FAIL on kernels without listns()
where the tests should SKIP.
- filelock: fix the break_lease() stub signature for
CONFIG_FILE_LOCKING=n.
- init/initramfs_test: wait for the async initramfs unpacking before
running; the test and do_populate_rootfs() share the parser state.
- fs/coredump: reduce redundant log noise in
validate_coredump_safety().
- iomap: pass the correct length to fserror_report_io() in
__iomap_write_begin().
- backing-file: fix the backing_file_open() kerneldoc.
Cleanups
- initramfs: refactor the cpio hex header parsing to use hex2bin()
instead of the hand-rolled simple_strntoul() which is reverted, and
extend the initramfs KUnit tests to cover header fields with 0x
prefixes.
- Replace __get_free_pages() and friends with kmalloc()/kzalloc()
across quota, proc, ocfs2/dlm, nilfs2, nfs, nfsd, libfs, jfs, jbd2,
isofs, fuse, select, namespace, configfs, binfmt_misc, bfs, and the
do_mounts init code - part of the larger work of replacing page
allocator calls with kmalloc().
- Use clear_and_wake_up_bit() in unlock_buffer() and
journal_end_buffer_io_sync() instead of open-coding the sequence.
- Drop unused VFS exports: unexport drop_super_exclusive(), remove
start_removing_user_path_at(), and fold __start_removing_path() into
start_removing_path().
- fs/read_write: narrow the __kernel_write() export with
EXPORT_SYMBOL_FOR_MODULES().
- vfs: uapi: retire octal and hex constants in favor of (1 << n) for
the O_ flags. Finding a free bit for a new flag across the
architectures was needlessly hard with the mixed bases.
- dcache: add extra sanity checks of dead dentries in dentry_free()
via a new DENTRY_WARN_ONCE() that also prints d_flags.
- iov_iter: use kmemdup_array() in dup_iter() to harden the allocation
against multiplication overflow.
- fs/pipe: write to ->poll_usage only once.
- vfs: remove an always-taken if-branch in find_next_fd().
- dcache: use kmalloc_flex() for struct external_name in __d_alloc().
- namei: use QSTR() instead of QSTR_INIT() in path_pts().
- sync_file_range: delete dead S_ISLNK code.
- Comment fixes: retire a stale comment in fget_task_next() and fix
assorted spelling mistakes.
/* Testing */
gcc (Debian 14.2.0-19) 14.2.0
Debian clang version 19.1.7 (3+b1)
No build failures or warnings were observed.
/* Conflicts */
Merge conflicts with mainline
=============================
No known conflicts.
Merge conflicts with other trees
================================
This has a merge conflict with the ext4 tree in fs/jbd2/journal.c
between commit bbe9015f23432b ("jbd2: remove special jbd2 slabs") from
the ext4 tree and commit 2f6702dc6fdcf0 ("jbd2: replace
__get_free_pages() with kmalloc()") from this tree. The change in this
tree is a subset of the ext4 tree's commit, so the conflict can be
resolved by taking the ext4 side. Reported in [1].
It was suggested in [2] to drop the patch from this tree. But the
patch is part of the merged "fs: replace __get_free_pages() call with
kmalloc()" series with a dozen commits on top of it, so dropping it
would have meant rewriting the whole branch after it had been exposed
in linux-next. Since the change is a strict subset of the ext4 commit,
taking the ext4 side during the merge yields the identical end result.
[1]: https://lore.kernel.org/linux-next/aiq8CByJNMlXo6Be@xxxxxxxxxxxx
[2]: https://lore.kernel.org/linux-next/airBGjtjTf3Yuy0X@xxxxxxxxxxxxxxxxxxxx
The following changes since commit 254f49634ee16a731174d2ae34bc50bd5f45e731:
Linux 7.1-rc1 (2026-04-26 14:19:00 -0700)
are available in the Git repository at:
git@xxxxxxxxxxxxxxxxxxx:pub/scm/linux/kernel/git/vfs/vfs tags/vfs-7.2-rc1.misc
for you to fetch changes up to aa5c4fe3ba0cb2af90bbcfa7a8ef4fefcd5c2370:
backing-file: fix backing_file_open() kerneldoc parameter (2026-06-10 09:49:25 +0200)
----------------------------------------------------------------
vfs-7.2-rc1.misc
Please consider pulling these changes from the signed vfs-7.2-rc1.misc tag.
Thanks!
Christian
----------------------------------------------------------------
Agatha Isabelle Moreira (2):
fs: buffer: use clear_and_wake_up_bit() in unlock_buffer()
fs: jbd2: use clear_and_wake_up_bit() in journal_end_buffer_io_sync()
Al Viro (1):
mount: honour SB_NOUSER in the new mount API
Alexey Dobriyan (1):
sync_file_range: delete dead S_ISLNK code
Amir Goldstein (1):
docs: add guidelines for submitting new filesystems
Andy Shevchenko (5):
initramfs: Sort headers alphabetically
initramfs: Refactor to use hex2bin() instead of custom approach
vsprintf: Revert "add simple_strntoul"
kstrtox: Drop extern keyword in the simple_strtox() declarations
fs/read_write: Do not export __kernel_write() to the entire world
Breno Leitao (2):
fs/pipe: pre-allocate pages outside pipe->mutex in anon_pipe_write
selftests/pipe: add pipe_bench microbenchmark
Christian Brauner (11):
Merge patch series "uaccess/sockptr: copy_struct_ fixes and more helpers"
Merge patch series "selftests/namespaces: Fix test hangs and false failures"
Merge patch series "initramfs: test and improve cpio hex header validation"
Merge patch series "drop unused VFS exports"
Merge patch series "fix crashes when mounting legacy file system with sector size > PAGE_SIZE"
Merge patch series "fs: refactor code to use clear_and_wake_up_bit()"
Merge patch series "fs: replace __get_free_pages() call with kmalloc()"
Merge patch series "fs/pipe: reduce pipe->mutex contention by pre-allocating outside the lock"
Merge patch series "libfs: set SB_I_NOEXEC and SB_I_NODEV in init_pseudo()"
bpf: add bpf_real_inode() kfunc
filelock: fix break_lease() stub signature for CONFIG_FILE_LOCKING=n
Christoph Hellwig (15):
fs: unexport drop_super_exclusive
fs: remove start_removing_user_path_at
fs: fold __start_removing_path into start_removing_path
bfs: handle set_blocksize failures
hpfs: handle set_blocksize failures
qnx4: handle set_blocksize failures
jfs: handle set_blocksize failures
befs: handle set_blocksize failures
affs: handle set_blocksize failures
isofs: handle set_blocksize failures
minix: handle set_blocksize failures
ntfs3: handle set_blocksize failures
omfs: handle set_blocksize failures
minix: release the sb buffer_head when setting the v3 block size fails
iomap: pass the correct len to fserror_report_io in __iomap_write_begin
David Disseldorp (2):
initramfs_test: add fill_cpio() inject_ox parameter
initramfs_test: test header fields with 0x hex prefix
Jeff Layton (2):
dcache: add extra sanity checks of the dentry in dentry_free()
vfs: add FS_USERNS_DELEGATABLE flag and set it for NFS
Jia He (1):
init/initramfs_test: wait_for_initramfs() before running
John Hubbard (2):
libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo()
libfs: drop redundant SB_I_NOEXEC/SB_I_NODEV in init_pseudo() callers
Jori Koolstra (2):
vfs: remove always taken if-branch in find_next_fd()
vfs: uapi: retire octal and hex numbers in favor of (1 << n) for O_ flags
Li RongQing (1):
fs/coredump: reduce redundant log noise in validate_coredump_safety
Li Wang (1):
backing-file: fix backing_file_open() kerneldoc parameter
Mateusz Guzik (2):
fs/pipe: write to ->poll_usage only once
fs: retire stale comment in fget_task_next()
Mike Rapoport (Microsoft) (18):
init: do_mounts: use kmalloc() for allocations of temporary buffers
quota: allocate dquot_hash with kmalloc()
proc: replace __get_free_page() with kmalloc()
ocfs2/dlm: replace __get_free_page() with kmalloc()
nilfs2: replace get_zeroed_page() with kzalloc()
NFS: replace __get_free_page() with kmalloc() in nfs_show_devname()
NFS: remove unused page and page2 in nfs4_replace_transport()
NFSD: replace __get_free_page() with kmalloc() in nfsd_buffered_readdir()
libfs: simple_transaction_get(): replace get_zeroed_page() with kzalloc()
jfs: replace __get_free_page() with kmalloc()
jbd2: replace __get_free_pages() with kmalloc()
isofs: replace __get_free_page() with kmalloc()
fuse: replace __get_free_page() with kmalloc()
fs/select: replace __get_free_page() with kmalloc()
fs/namespace: use __getname() to allocate mntpath buffer
configfs: replace __get_free_pages() with kzalloc()
binfmt_misc: replace __get_free_page() with kmalloc()
bfs: replace get_zeroed_page() with kzalloc()
Mingyu Wang (1):
fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling
Qingshuang Fu (1):
fs: fix spelling mistakes in comment
Ricardo B. Marlière (3):
selftests/namespaces: Kill grandchild in nsid fixture teardown
selftests/namespaces: Fix waitpid race in listns_efault_test cleanup
selftests/namespaces: Skip efault tests when listns() is not available
Stefan Metzmacher (5):
uaccess: fix ignored_trailing logic in copy_struct_to_user()
sockptr: fix usize check in copy_struct_from_sockptr() for user pointers
uaccess: add copy_struct_{from,to}_bounce_buffer() helpers
sockptr: let copy_struct_from_sockptr() use copy_struct_from_bounce_buffer()
sockptr: introduce copy_struct_to_sockptr()
Thorsten Blum (2):
dcache: use kmalloc_flex() in __d_alloc
namei: use QSTR() instead of QSTR_INIT() in path_pts
Wang Haoran (1):
iov_iter: use kmemdup_array for dup_iter to harden against overflow
.../filesystems/adding-new-filesystems.rst | 195 +++++++
Documentation/filesystems/index.rst | 1 +
Documentation/filesystems/porting.rst | 1 -
arch/alpha/include/uapi/asm/fcntl.h | 34 +-
arch/arm/include/uapi/asm/fcntl.h | 8 +-
arch/arm64/include/uapi/asm/fcntl.h | 8 +-
arch/m68k/include/uapi/asm/fcntl.h | 8 +-
arch/mips/include/uapi/asm/fcntl.h | 22 +-
arch/parisc/include/uapi/asm/fcntl.h | 28 +-
arch/powerpc/include/uapi/asm/fcntl.h | 8 +-
arch/sparc/include/uapi/asm/fcntl.h | 34 +-
fs/affs/affs.h | 5 -
fs/affs/super.c | 6 +-
fs/aio.c | 1 -
fs/anon_inodes.c | 2 -
fs/backing-file.c | 13 +-
fs/befs/linuxvfs.c | 3 +-
fs/bfs/inode.c | 7 +-
fs/binfmt_misc.c | 4 +-
fs/bpf_fs_kfuncs.c | 16 +
fs/buffer.c | 4 +-
fs/configfs/file.c | 7 +-
fs/coredump.c | 3 +-
fs/dcache.c | 18 +-
fs/exec.c | 6 +-
fs/fcntl.c | 8 +-
fs/file.c | 18 +-
fs/file_table.c | 4 +-
fs/fuse/ioctl.c | 5 +-
fs/hpfs/super.c | 3 +-
fs/iomap/buffered-io.c | 2 +-
fs/isofs/dir.c | 5 +-
fs/isofs/inode.c | 3 +-
fs/jbd2/commit.c | 4 +-
fs/jbd2/journal.c | 7 +-
fs/jfs/jfs_dtree.c | 16 +-
fs/jfs/super.c | 3 +-
fs/libfs.c | 7 +-
fs/minix/inode.c | 3 +-
fs/namei.c | 25 +-
fs/namespace.c | 11 +-
fs/nfs/fs_context.c | 8 +-
fs/nfs/nfs4namespace.c | 15 +-
fs/nfs/super.c | 4 +-
fs/nfsd/vfs.c | 4 +-
fs/nilfs2/ioctl.c | 4 +-
fs/nsfs.c | 1 -
fs/ntfs3/super.c | 8 +-
fs/ocfs2/dlm/dlmdebug.c | 24 +-
fs/ocfs2/dlm/dlmdomain.c | 8 +-
fs/ocfs2/dlm/dlmmaster.c | 5 +-
fs/ocfs2/dlm/dlmrecovery.c | 4 +-
fs/omfs/inode.c | 6 +-
fs/pidfs.c | 2 -
fs/pipe.c | 106 +++-
fs/proc/base.c | 16 +-
fs/qnx4/inode.c | 3 +-
fs/quota/dquot.c | 11 +-
fs/read_write.c | 5 +-
fs/select.c | 4 +-
fs/super.c | 12 +-
fs/sync.c | 3 +-
include/linux/filelock.h | 2 +-
include/linux/fs.h | 1 +
include/linux/kstrtox.h | 9 +-
include/linux/namei.h | 1 -
include/linux/sockptr.h | 28 +-
include/linux/uaccess.h | 65 ++-
include/uapi/asm-generic/fcntl.h | 50 +-
init/do_mounts.c | 21 +-
init/initramfs.c | 68 ++-
init/initramfs_test.c | 97 +++-
lib/iov_iter.c | 8 +-
lib/vsprintf.c | 7 -
mm/secretmem.c | 2 -
tools/testing/selftests/Makefile | 1 +
.../selftests/namespaces/listns_efault_test.c | 33 +-
tools/testing/selftests/namespaces/nsid_test.c | 14 +-
tools/testing/selftests/pipe/.gitignore | 1 +
tools/testing/selftests/pipe/Makefile | 9 +
tools/testing/selftests/pipe/pipe_bench.c | 616 +++++++++++++++++++++
virt/kvm/guest_memfd.c | 2 -
82 files changed, 1464 insertions(+), 390 deletions(-)
create mode 100644 Documentation/filesystems/adding-new-filesystems.rst
create mode 100644 tools/testing/selftests/pipe/.gitignore
create mode 100644 tools/testing/selftests/pipe/Makefile
create mode 100644 tools/testing/selftests/pipe/pipe_bench.c