Pull dcache updates from Al Viro:
- d_alloc_parallel() API change (Neil's with my changes)
- NORCU fixes
- Reorganization and simplification of dentry eviction logic
- Simplifying rcu_read_lock() scopes in fs/dcache.c
- Secondary roots work - getting rid of NFS fake root dentries and
dealing with remaining shrink_dcache_for_umount() and
shrink_dentry_list() races
- making cursors NORCU (surprisingly easy)
* tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (22 commits)
make cursors NORCU
nfs: get rid of fake root dentries
wind ->s_roots via ->d_sib instead of ->d_hash
shrink_dentry_tree(): unify the calls of shrink_dentry_list()
shrinking rcu_read_lock() scope in d_alloc_parallel()
d_walk(): shrink rcu_read_lock() scope
document dentry_kill()
adjust calling conventions of lock_for_kill(), fold __dentry_kill() into dentry_kill()
Document rcu_read_lock() use in select_collect2()
Shift rcu_read_{,un}lock() inside fast_dput()
simplify safety for lock_for_kill() slowpath
fold lock_for_kill() and __dentry_kill() into common helper
fold lock_for_kill() into shrink_kill()
shrink_dentry_list(): start with removing from shrink list
d_prune_aliases(): make sure to skip NORCU aliases
kill d_dispose_if_unused()
make to_shrink_list() return whether it has moved dentry to list
select_collect(): ignore dentries on shrink lists if they have positive refcounts
find_acceptable_alias(): skip NORCU aliases with zero refcount
fix a race between d_find_any_alias() and final dput() of NORCU dentries
...
Pull misc vfs updates from Christian Brauner:
"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"
* tag 'vfs-7.2-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (73 commits)
backing-file: fix backing_file_open() kerneldoc parameter
iomap: pass the correct len to fserror_report_io in __iomap_write_begin
vfs: add FS_USERNS_DELEGATABLE flag and set it for NFS
filelock: fix break_lease() stub signature for CONFIG_FILE_LOCKING=n
vfs: uapi: retire octal and hex numbers in favor of (1 << n) for O_ flags
bpf: add bpf_real_inode() kfunc
fs/read_write: Do not export __kernel_write() to the entire world
libfs: drop redundant SB_I_NOEXEC/SB_I_NODEV in init_pseudo() callers
libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo()
mount: honour SB_NOUSER in the new mount API
fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling
selftests/pipe: add pipe_bench microbenchmark
fs/pipe: pre-allocate pages outside pipe->mutex in anon_pipe_write
fs: retire stale comment in fget_task_next()
fs: fix spelling mistakes in comment
bfs: replace get_zeroed_page() with kzalloc()
binfmt_misc: replace __get_free_page() with kmalloc()
configfs: replace __get_free_pages() with kzalloc()
fs/namespace: use __getname() to allocate mntpath buffer
fs/select: replace __get_free_page() with kmalloc()
...
Pull openat2 updates from Christian Brauner:
"Features:
- Add O_EMPTYPATH to openat(2)/openat2(2). To get an operable file
descriptor from an O_PATH file descriptor it is possible to use
openat(fd, ".", O_DIRECTORY) for directories, but other file types
require going through open("/proc/<pid>/fd/<nr>") and thus depend
on a functioning procfs.
With O_EMPTYPATH an empty path string is accepted and LOOKUP_EMPTY
is set at path resolution time, allowing to reopen the file behind
the file descriptor directly. Selftests are included.
- Add an OPENAT2_REGULAR flag for openat2(2) which refuses to open
anything but regular files with the new EFTYPE error code.
This implements the "ability to only open regular files" feature
requested by userspace via uapi-group.org and protects services
from being redirected to fifos, device nodes, and friends.
All atomic_open implementations were audited for OPENAT2_REGULAR
handling. Explicit checks were added to ceph, gfs2, nfs (v4), and
cifs/smb - these are the filesystems whose atomic_open can
encounter an existing non-regular file and would otherwise call
finish_open() on it or return a misleading error code.
The remaining implementations (9p, fuse, vboxsf, nfs v2/v3) only
call finish_open() on freshly created files and use
finish_no_open() for lookup hits, letting the VFS catch non-regular
files via the do_open() safety net.
Cleanups:
- Migrate the openat2 selftests to the kselftest harness and move
them under selftests/filesystems/. The tests were written in the
early days of selftests' TAP support and the modern kselftest
harness is much easier to follow and maintain. The contents of the
tests are unchanged and the new emptypath tests are ported on top.
- Make the LAST_XXX last-type constants private to fs/namei.c. The
only user outside of fs/namei.c was ksmbd which only needs to know
whether the last component is a regular one, so
vfs_path_parent_lookup() now performs the LAST_NORM check
internally. The ints are replaced with a dedicated enum last_type"
* tag 'vfs-7.2-rc1.openat2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
vfs: replace ints with enum last_type for LAST_XXX
vfs: make LAST_XXX private to fs/namei.c
selftests: openat2: port emptypath_test to kselftest harness
kselftest/openat2: test for OPENAT2_REGULAR flag
openat2: new OPENAT2_REGULAR flag support
openat2: introduce EFTYPE error code
selftest: add tests for O_EMPTYPATH
vfs: add O_EMPTYPATH to openat(2)/openat2(2)
selftests: openat2: migrate to kselftest harness
selftests: openat2: switch from custom ARRAY_LEN to ARRAY_SIZE
selftests: openat2: move helpers to header
selftests: move openat2 tests to selftests/filesystems/
Pull vfs directory delegations from Christian Brauner:
"This contains the VFS prerequisites for supporting directory
delegations in nfsd via CB_NOTIFY callbacks.
The filelock core gains support for ignoring delegation breaks for
directory change events together with an inode_lease_ignore_mask()
helper, and fsnotify gains fsnotify_modify_mark_mask() and a
FSNOTIFY_EVENT_RENAME data type.
With this in place nfsd can request delegations on directories and set
up inotify watches to trigger sending CB_NOTIFY events to clients
instead of having every directory change break the delegation.
New tracepoints are added to fsnotify() and to the start of
break_lease(), and trace_break_lease_block() is passed the currently
blocking lease instead of the new one.
A follow-up fix moves the LEASE_BREAK_* flags out of
#ifdef CONFIG_FILE_LOCKING to fix the build for CONFIG_FILE_LOCKING=n
configurations"
* tag 'vfs-7.2-rc1.directory.delegations' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
filelock: move LEASE_BREAK_* flags out of #ifdef CONFIG_FILE_LOCKING
fsnotify: add FSNOTIFY_EVENT_RENAME data type
fsnotify: add fsnotify_modify_mark_mask()
fsnotify: new tracepoint in fsnotify()
filelock: add an inode_lease_ignore_mask helper
filelock: add a tracepoint to start of break_lease()
filelock: add support for ignoring deleg breaks for dir change events
filelock: pass current blocking lease to trace_break_lease_block() rather than "new_fl"
Parallel lookup starts with a call of d_alloc_parallel(). That primitive
either returns a matching hashed dentry or allocates a new one in the
in-lookup state and returns it to the caller. Once the caller is done
with lookup, it indicates so either by call of d_{splice_alias,add}()
or by call of d_done_lookup(); at that point dentry leaves the in-lookup
state.
If d_alloc_parallel() finds a matching in-lookup dentry, it must wait for
that dentry to leave the in-lookup state, one way or another. Currently
by supplying wait_queue_head to d_alloc_parallel(). If d_alloc_parallel()
creates a new in-lookup dentry, the address of that wait_queue_head is stored
in ->d_wait of new dentry and stays there while it's in the in-lookup;
subsequent d_alloc_parallel() will wait on the queue found in the matching
in-lookup dentry. Transition out of in-lookup state wakes waiters on that
queue (if any).
That works, but the calling conventions are inconvenient - the caller must
supply wait_queue_head and make sure that it survives at least until the new
in-lookup dentry leaves the in-lookup state. That amounts to boilerplate
in the d_alloc_parallel() callers that are followed by a call of d_lookup_done()
in the same function; in cases like nfs asynchronous unlink it gets worse than
that.
This patch changes d_alloc_parallel() to use wake_up_var_locked() to
wake up waiters, and wait_var_event_spinlock() to wait. dentry->d_lock
is used for synchronisation as it is already held and the relevant
times.
That eliminates the need of caller-supplied wait_queue_head, simplifying
the calling conventions. Better yet, we only need one bit of information
stored in dentry itself: whether there are any waiters to be woken up,
and that can be easily stored in ->d_flags; ->d_wait goes away.
The reason we need that bit (DCACHE_LOOKUP_WAITERS) is that with wait_var
machinery the queues are shared with all kinds of stuff and there's
no way tell if any of the waiters have anything to do with our dentry;
most of the time none of them will be relevant, so we need to avoid the
pointless wakeups.
Another benefit of the new scheme comes from the fact that wakeups
have to be done outside of write-side critical areas of ->i_dir_seq;
with the old scheme we need to carry the value picked from ->d_wait from
__d_lookup_unhash() to the place where we actually wake the waiters up.
Now we can just leave DCACHE_LOOKUP_WAITERS in ->d_flags until we get
to doing wakeups - that's done within the same ->d_lock scope, so we
are fine; new bit is accessed only under ->d_lock and it's seen only
on dentries with DCACHE_PAR_LOOKUP in ->d_flags.
__d_lookup_unhash() no longer needs to re-init ->d_lru. That was
previously shared (in a union) with ->d_wait but ->d_wait is now gone
so it no longer corrupts ->d_lru.
Co-developed-by: Al Viro <viro@zeniv.linux.org.uk> # saner handling of flags
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Several functions in namei.c take an "int *type" parameter, such as
filename_parentat(). To know what values this can take you have to find
the anonymous struct that defines the LAST_XXX values. Define an enum
last_type to make this type explicit.
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Link: https://patch.msgid.link/20260528175854.57626-2-jkoolstra@xs4all.nl
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
The only user of LAST_XXX outside of fs/namei.c is fs/smb/server/vfs.c;
ksmbd_vfs_path_lookup() calls vfs_path_parent_lookup() and expects a
LAST_NORM last type (or it will be ENOENT). ksmbd_vfs_rename() also calls
vfs_path_parent_lookup() but forgets the LAST_NORM check.
It does not really make sense to have vfs_path_parent_lookup() expose
the last_type because it is only needed to ensure it is LAST_NORM. So
let's do this check in vfs_path_parent_lookup() instead and keep the
LAST_XXX internal to fs/namei.c. This changes the ENOENT errno in
ksmbd_vfs_path_lookup() to EINVAL, which matches better with how this is
handled by callers of filename_parentat().
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
Link: https://patch.msgid.link/20260528175854.57626-1-jkoolstra@xs4all.nl
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: NeilBrown <neil@brown.name>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
atomic_create() in fs/namei.c drops the reference to the dentry
when it returns an error.
This behaviour was imported into dentry_create() so that it
will drop the reference if an error is returned from atomic_create(),
though not if vfs_create() returns an error (in the case where
->atomic_create is not supported).
The caller - nfsd4_create_file() - is made aware of this by checking
path->dentry, which will either be a counted reference to a dentry, or
an error pointer.
However the change to use start_creating()/end_creating() (which landed
shortly before the dentry_create() change landed, though was likely
developed around the same time) means that nfsd4_create_file() *needs* a
valid dentry so that it can unlock the parent.
The net result is that if NFSD exports a filesystem which uses
->atomic_create, and if a call to ->atomic_create returns an error, then
nfsd4_create_file() will pass an error pointer to end_creating()
and the parent will not be unlocked.
Fix this by changing dentry_create() to make sure path->dentry is always
a valid dentry, never an error-pointer. The actual error is already
returned a different way.
Note that if ->atomic_create() returns a different dentry (which may not
be possible in practice) we are guaranteed (because it is only ever
provided by d_spliace_alias()) that it will have the same d_parent and
so it will have the same effect when passed to end_creating().
Fixes: 64a989dbd1 ("VFS/knfsd: Teach dentry_create() to use atomic_open()")
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/177969022571.3379282.16448744624428323496@noble.neil.brown.name
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Benjamin Coddington <bcodding@hammerspace.com>
Reviewed-by: Jori Koolstra <jkoolstra@xs4all.nl>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This flag indicates the path should be opened if it's a regular file.
This is useful to write secure programs that want to avoid being
tricked into opening device nodes with special semantics while thinking
they operate on regular files. This is a requested feature from the
uapi-group[1].
The previously introduced EFTYPE error code is returned when the path
doesn't refer to a regular file. For example, if openat2 is called on
path /dev/null with OPENAT2_REGULAR in the flag param, it will return
-EFTYPE.
When used in combination with O_CREAT, either the regular file is
created, or if the path already exists, it is opened if it's a regular
file. Otherwise, -EFTYPE is returned.
When OPENAT2_REGULAR is combined with O_DIRECTORY, -EINVAL is returned
as it doesn't make sense to open a path that is both a directory and a
regular file.
The UAPI bit lives in the upper 32 bits of open_how::flags
(((__u64)1 << 32)) so that open(2) and openat(2) -- whose @flags
argument is a C int -- cannot physically express it. This is a
structural guarantee, not a runtime mask: the bit is unrepresentable in
32 bits.
Because the rest of the VFS open path narrows to 32 bits in several
places (op->open_flag, f->f_flags, the unsigned open_flag argument of
i_op->atomic_open()), build_open_flags() translates OPENAT2_REGULAR
into a kernel-internal lower-32-bit carrier __O_REGULAR (bit 4, unused
as an O_* on every architecture) before the assignment to op->open_flag.
__O_REGULAR then rides through the existing channels exactly like
__FMODE_EXEC. do_dentry_open() strips it so it cannot leak back to
userspace via fcntl(F_GETFL).
Four BUILD_BUG_ON_MSG() invariants in build_open_flags() prevent any
future bit collision or accidental low-32 redefinition:
- VALID_OPEN_FLAGS fits in 32 bits.
- OPENAT2_REGULAR lives in the upper 32 bits.
- OPENAT2_REGULAR does not alias any open()/openat() flag.
- __O_REGULAR does not alias any user-visible flag.
[1]: https://uapi-group.org/kernel-features/#ability-to-only-open-regular-files
Christian Brauner <brauner@kernel.org> says:
Move OPENAT2_REGULAR to the upper 32 bits of open_how::flags with a
kernel-internal __O_REGULAR carrier so that open(2)/openat(2) cannot
encode the flag; add BUILD_BUG_ON_MSG() invariants and register
__O_REGULAR in the fcntl_init() allocation-uniqueness BUILD_BUG_ON()
(bit count 21 -> 22).
Signed-off-by: Dorjoy Chowdhury <dorjoychy111@gmail.com>
Link: https://patch.msgid.link/20260328172314.45807-2-dorjoychy111@gmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Aleksa Sarai <aleksa@amutable.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
If a NFS client requests a directory delegation with a notification
bitmask covering directory change events, the server shouldn't recall
the delegation. Instead the client will be notified of the change after
the fact.
Add support for ignoring lease breaks on directory changes. Add a new
flags parameter to try_break_deleg() and teach __break_lease how to
ignore certain types of delegation break events.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260428-dir-deleg-v3-2-5a0780ba9def@kernel.org
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull vfs directory updates from Christian Brauner:
"Recently 'start_creating', 'start_removing', 'start_renaming' and
related interfaces were added which combine the locking and the
lookup.
At that time many callers were changed to use the new interfaces.
However there are still an assortment of places out side of the core
vfs where the directory is locked explictly, whether with inode_lock()
or lock_rename() or similar. These were missed in the first pass for
an assortment of uninteresting reasons.
This addresses the remaining places where explicit locking is used,
and changes them to use the new interfaces, or otherwise removes the
explicit locking.
The biggest changes are in overlayfs. The other changes are quite
simple, though maybe the cachefiles changes is the least simple of
those"
* tag 'vfs-7.1-rc1.directory' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
VFS: unexport lock_rename(), lock_rename_child(), unlock_rename()
ovl: remove ovl_lock_rename_workdir()
ovl: use is_subdir() for testing if one thing is a subdir of another
ovl: change ovl_create_real() to get a new lock when re-opening created file.
ovl: pass name buffer to ovl_start_creating_temp()
cachefiles: change cachefiles_bury_object to use start_renaming_dentry()
ovl: Simplify ovl_lookup_real_one()
VFS: make lookup_one_qstr_excl() static.
nfsd: switch purge_old() to use start_removing_noperm()
selinux: Use simple_start_creating() / simple_done_creating()
Apparmor: Use simple_start_creating() / simple_done_creating()
libfs: change simple_done_creating() to use end_creating()
VFS: move the start_dirop() kerndoc comment to before start_dirop()
fs/proc: Don't lock root inode when creating "self" and "thread-self"
VFS: note error returns in documentation for various lookup functions
This kerneldoc comment was always meant for start_dirop(), not for
__start_dirop() which is a static function and doesn't need
documentation.
It was in the wrong place and was then incorrectly renamed (instead of
moved) and useless "documentation" was added for "@state" was provided.
This patch reverts the name, removes the mention of @state, and moves
the comment to where it belongs.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20260224222542.3458677-4-neilb@ownmail.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
Pull more misc vfs updates from Christian Brauner:
"Features:
- Optimize close_range() from O(range size) to O(active FDs) by using
find_next_bit() on the open_fds bitmap instead of linearly scanning
the entire requested range. This is a significant improvement for
large-range close operations on sparse file descriptor tables.
- Add FS_XFLAG_VERITY file attribute for fs-verity files, retrievable
via FS_IOC_FSGETXATTR and file_getattr(). The flag is read-only.
Add tracepoints for fs-verity enable and verify operations,
replacing the previously removed debug printk's.
- Prevent nfsd from exporting special kernel filesystems like pidfs
and nsfs. These filesystems have custom ->open() and ->permission()
export methods that are designed for open_by_handle_at(2) only and
are incompatible with nfsd. Update the exportfs documentation
accordingly.
Fixes:
- Fix KMSAN uninit-value in ovl_fill_real() where strcmp() was used
on a non-null-terminated decrypted directory entry name from
fscrypt. This triggered on encrypted lower layers when the
decrypted name buffer contained uninitialized tail data.
The fix also adds VFS-level name_is_dot(), name_is_dotdot(), and
name_is_dot_dotdot() helpers, replacing various open-coded "." and
".." checks across the tree.
- Fix read-only fsflags not being reset together with xflags in
vfs_fileattr_set(). Currently harmless since no read-only xflags
overlap with flags, but this would cause inconsistencies for any
future shared read-only flag
- Return -EREMOTE instead of -ESRCH from PIDFD_GET_INFO when the
target process is in a different pid namespace. This lets userspace
distinguish "process exited" from "process in another namespace",
matching glibc's pidfd_getpid() behavior
Cleanups:
- Use C-string literals in the Rust seq_file bindings, replacing the
kernel::c_str!() macro (available since Rust 1.77)
- Fix typo in d_walk_ret enum comment, add porting notes for the
readlink_copy() calling convention change"
* tag 'vfs-7.0-rc1.misc.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: add porting notes about readlink_copy()
pidfs: return -EREMOTE when PIDFD_GET_INFO is called on another ns
nfsd: do not allow exporting of special kernel filesystems
exportfs: clarify the documentation of open()/permission() expotrfs ops
fsverity: add tracepoints
fs: add FS_XFLAG_VERITY for fs-verity files
rust: seq_file: replace `kernel::c_str!` with C-Strings
fs: dcache: fix typo in enum d_walk_ret comment
ovl: use name_is_dot* helpers in readdir code
fs: add helpers name_is_dot{,dot,_dotdot}
ovl: Fix uninit-value in ovl_fill_real
fs: reset read-only fsflags together with xflags
fs/file: optimize close_range() complexity from O(N) to O(Sparse)
Pull vfs 'struct filename' updates from Al Viro:
"[Mostly] sanitize struct filename handling"
* tag 'pull-filename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (68 commits)
sysfs(2): fs_index() argument is _not_ a pathname
alpha: switch osf_mount() to strndup_user()
ksmbd: use CLASS(filename_kernel)
mqueue: switch to CLASS(filename)
user_statfs(): switch to CLASS(filename)
statx: switch to CLASS(filename_maybe_null)
quotactl_block(): switch to CLASS(filename)
chroot(2): switch to CLASS(filename)
move_mount(2): switch to CLASS(filename_maybe_null)
namei.c: switch user pathname imports to CLASS(filename{,_flags})
namei.c: convert getname_kernel() callers to CLASS(filename_kernel)
do_f{chmod,chown,access}at(): use CLASS(filename_uflags)
do_readlinkat(): switch to CLASS(filename_flags)
do_sys_truncate(): switch to CLASS(filename)
do_utimes_path(): switch to CLASS(filename_uflags)
chdir(2): unspaghettify a bit...
do_fchownat(): unspaghettify a bit...
fspick(2): use CLASS(filename_flags)
name_to_handle_at(): use CLASS(filename_uflags)
vfs_open_tree(): use CLASS(filename_uflags)
...
Pull misc vfs updates from Christian Brauner:
"This contains a mix of VFS cleanups, performance improvements, API
fixes, documentation, and a deprecation notice.
Scalability and performance:
- Rework pid allocation to only take pidmap_lock once instead of
twice during alloc_pid(), improving thread creation/teardown
throughput by 10-16% depending on false-sharing luck. Pad the
namespace refcount to reduce false-sharing
- Track file lock presence via a flag in ->i_opflags instead of
reading ->i_flctx, avoiding false-sharing with ->i_readcount on
open/close hot paths. Measured 4-16% improvement on 24-core
open-in-a-loop benchmarks
- Use a consume fence in locks_inode_context() to match the
store-release/load-consume idiom, eliminating a hardware fence on
some architectures
- Annotate cdev_lock with __cacheline_aligned_in_smp to prevent
false-sharing
- Remove a redundant DCACHE_MANAGED_DENTRY check in
__follow_mount_rcu() that never fires since the caller already
verifies it, eliminating a 100% mispredicted branch
- Fix a 100% mispredicted likely() in devcgroup_inode_permission()
that became wrong after a prior code reorder
Bug fixes and correctness:
- Make insert_inode_locked() wait for inode destruction instead of
skipping, fixing a corner case where two matching inodes could
exist in the hash
- Move f_mode initialization before file_ref_init() in alloc_file()
to respect the SLAB_TYPESAFE_BY_RCU ordering contract
- Add a WARN_ON_ONCE guard in try_to_free_buffers() for folios with
no buffers attached, preventing a null pointer dereference when
AS_RELEASE_ALWAYS is set but no release_folio op exists
- Fix select restart_block to store end_time as timespec64, avoiding
truncation of tv_sec on 32-bit architectures
- Make dump_inode() use get_kernel_nofault() to safely access inode
and superblock fields, matching the dump_mapping() pattern
API modernization:
- Make posix_acl_to_xattr() allocate the buffer internally since
every single caller was doing it anyway. Reduces boilerplate and
unnecessary error checking across ~15 filesystems
- Replace deprecated simple_strtoul() with kstrtoul() for the
ihash_entries, dhash_entries, mhash_entries, and mphash_entries
boot parameters, adding proper error handling
- Convert chardev code to use guard(mutex) and __free(kfree) cleanup
patterns
- Replace min_t() with min() or umin() in VFS code to avoid silently
truncating unsigned long to unsigned int
- Gate LOOKUP_RCU assertions behind CONFIG_DEBUG_VFS since callers
already check the flag
Deprecation:
- Begin deprecating legacy BSD process accounting (acct(2)). The
interface has numerous footguns and better alternatives exist
(eBPF)
Documentation:
- Fix and complete kernel-doc for struct export_operations, removing
duplicated documentation between ReST and source
- Fix kernel-doc warnings for __start_dirop() and ilookup5_nowait()
Testing:
- Add a kunit test for initramfs cpio handling of entries with
filesize > PATH_MAX
Misc:
- Add missing <linux/init_task.h> include in fs_struct.c"
* tag 'vfs-7.0-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (28 commits)
posix_acl: make posix_acl_to_xattr() alloc the buffer
fs: make insert_inode_locked() wait for inode destruction
initramfs_test: kunit test for cpio.filesize > PATH_MAX
fs: improve dump_inode() to safely access inode fields
fs: add <linux/init_task.h> for 'init_fs'
docs: exportfs: Use source code struct documentation
fs: move initializing f_mode before file_ref_init()
exportfs: Complete kernel-doc for struct export_operations
exportfs: Mark struct export_operations functions at kernel-doc
exportfs: Fix kernel-doc output for get_name()
acct(2): begin the deprecation of legacy BSD process accounting
device_cgroup: remove branch hint after code refactor
VFS: fix __start_dirop() kernel-doc warnings
fs: Describe @isnew parameter in ilookup5_nowait()
fs/namei: Remove redundant DCACHE_MANAGED_DENTRY check in __follow_mount_rcu
fs: only assert on LOOKUP_RCU when built with CONFIG_DEBUG_VFS
select: store end_time as timespec64 in restart block
chardev: Switch to guard(mutex) and __free(kfree)
namespace: Replace simple_strtoul with kstrtoul to parse boot params
dcache: Replace simple_strtoul with kstrtoul in set_dhash_entries
...
Pull vfs atomic_open updates from Christian Brauner:
"Allow knfsd to use atomic_open()
While knfsd offers combined exclusive create and open results to
clients, on some filesystems those results are not atomic. The
separate vfs_create() + vfs_open() sequence in dentry_create() can
produce races and unexpected errors. For example, open O_CREAT with
mode 0 will succeed in creating the file but return -EACCES from
vfs_open(). Additionally, network filesystems benefit from reducing
remote round-trip operations by using a single atomic_open() call.
Teach dentry_create() -- whose sole caller is knfsd -- to use
atomic_open() for filesystems that support it"
* tag 'vfs-7.0-rc1.atomic_open' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs/namei: fix kernel-doc markup for dentry_create
VFS/knfsd: Teach dentry_create() to use atomic_open()
VFS: Prepare atomic_open() for dentry_create()
VFS: move dentry_create() from fs/open.c to fs/namei.c
Pull vfs updates for btrfs from Christian Brauner:
"This contains some changes for btrfs that are taken to the vfs tree to
stop duplicating VFS code for subvolume/snapshot dentry
Btrfs has carried private copies of the VFS may_delete() and
may_create() functions in fs/btrfs/ioctl.c for permission checks
during subvolume creation and snapshot destruction. These copies have
drifted out of sync with the VFS originals — btrfs_may_delete() is
missing the uid/gid validity check and btrfs_may_create() is missing
the audit_inode_child() call.
Export the VFS functions as may_{create,delete}_dentry() and switch
btrfs to use them, removing ~70 lines of duplicated code"
* tag 'vfs-7.0-rc1.btrfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
btrfs: use may_create_dentry() in btrfs_mksubvol()
btrfs: use may_delete_dentry() in btrfs_ioctl_snap_destroy()
fs: export may_create() as may_create_dentry()
fs: export may_delete() as may_delete_dentry()
filename_flags is used by user_path_at(). I suspect that mixing
LOOKUP_EMPTY with real lookup flags had been a mistake all along; the
former belongs to pathname import, the latter - to pathwalk. Right now
none of the remaining in-tree callers of user_path_at() are getting
LOOKUP_EMPTY in flags, so user_path_at() could probably be switched
to CLASS(filename)...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
filename_renameat2() replaces do_renameat2(); unlike the latter,
it does not drop filename references - these days it can be just
as easily arranged in the caller.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
For many years btrfs as been using a copy of may_create() in
fs/btrfs/ioctl.c:btrfs_may_create(). Everytime may_create() is updated we
need to update the btrfs copy, and this is a maintenance burden. Currently
there are minor differences between both because the btrfs side lacks
updates done in may_create().
Export may_create() so that btrfs can use it and with the less generic
name may_create_dentry().
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Link: https://patch.msgid.link/ce5174bca079f4cdcbb8dd145f0924feb1f227cd.1768307858.git.fdmanana@suse.com
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
For many years btrfs as been using a copy of may_delete() in
fs/btrfs/ioctl.c:btrfs_may_delete(). Everytime may_delete() is updated we
need to update the btrfs copy, and this is a maintenance burden. Currently
there are minor differences between both because the btrfs side lacks
updates done in may_delete().
Export may_delete() so that btrfs can use it and with the less generic
name may_delete_dentry(). While at it change the calls in vfs_rmdir() to
pass a boolean literal instead of 1 and 0 as the last argument since the
argument has a bool type.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Link: https://patch.msgid.link/e09128fd53f01b19d0a58f0e7d24739f79f47f6d.1768307858.git.fdmanana@suse.com
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
"filp" thing never made sense; seeing that there are exactly 4 callers
in the entire tree (and it's neither exported nor even declared in
linux/*/*.h), there's no point keeping that ugliness.
FWIW, the 'filp' thing did originate in OSD&I; for some reason Tanenbaum
decided to call the object representing an opened file 'struct filp',
the last letter standing for 'position'. In all Unices, Linux included,
the corresponding object had always been 'struct file'...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The rest of the set_nameidata() callers treat IS_ERR(pathname) as
"bail out immediately with PTR_ERR(pathname) as error". Makes
life simpler for callers; do_filp_open() is the only exception
and its callers would also benefit from such calling conventions
change.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... 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>
s/names_cachep/names_cache/ for consistency with dentry cache.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
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>
Take the "long name" case into a helper (getname_long()). In
case of failure have the caller deal with freeing the original
struct filename.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
In case of long name don't reread what we'd already copied.
memmove() it instead. That avoids the possibility of ending
up with empty name there and the need to look at the flags
on the slow path.
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>
