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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
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)
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
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)
...
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
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
...
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
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
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
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()
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Rename the helper is_dot_dotdot() into the name_ namespace
and add complementary helpers to check for dot and dotdot
names individually.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://patch.msgid.link/20260128132406.23768-3-amir73il@gmail.com
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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O_ is interpreted as a broken hyperlink target. Escape _ with a backslash.
The asterisk in "struct file *" is interpreted as an opening emphasis
string that never closes. Replace double quotes with rST backticks.
Change "a ERR_PTR" to "an ERR_PTR".
Signed-off-by: Jay Winston <jaybenjaminwinston@gmail.com>
Link: https://patch.msgid.link/20260118110401.2651-1-jaybenjaminwinston@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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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>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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similar to previous commit; replacements are filename_{unlinkat,rmdir}()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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similar to previous commit; replacement is filename_mknodat()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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similar to previous commit; replacement is filename_mkdirat()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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similar to previous commit; replacement is filename_symlinkat()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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similar to previous commit; replacement is filename_linkat()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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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>
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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>
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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>
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"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>
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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>
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... 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>
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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>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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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>
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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>
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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>
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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>
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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>
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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>
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Same as init_unlink() and init_rmdir() already are; the only obstacle
is do_mknodat() being static.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Sphinx report kernel-doc warnings:
WARNING: ./fs/namei.c:2853 function parameter 'state' not described in '__start_dirop'
WARNING: ./fs/namei.c:2853 expecting prototype for start_dirop(). Prototype was for __start_dirop() instead
Fix them up.
Fixes: ff7c4ea11a05c8 ("VFS: add start_creating_killable() and start_removing_killable()")
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://patch.msgid.link/20251219024620.22880-3-bagasdotme@gmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The check for DCACHE_MANAGED_DENTRY at the start of __follow_mount_rcu()
is redundant because the only caller (handle_mounts) already verifies
d_managed(dentry) before calling this function, so, dentry in
__follow_mount_rcu() has always DCACHE_MANAGED_DENTRY set.
This early-out optimization never fires in practice - but it is marking
as likely().
This was detected with branch profiling, which shows 100% misprediction
in this likely.
Remove the whole if clause instead of removing the likely, given we
know for sure that dentry is not DCACHE_MANAGED_DENTRY.
Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20260105-dcache-v1-1-f0d904b4a7c2@debian.org
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Calls to the 2 modified routines are explicitly gated with checks for
the flag, so there is no use for this in production kernels.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251229125751.826050-1-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Sphinx report kernel-doc warnings:
WARNING: ./fs/namei.c:2853 function parameter 'state' not described in '__start_dirop'
WARNING: ./fs/namei.c:2853 expecting prototype for start_dirop(). Prototype was for __start_dirop() instead
Fix them up.
Fixes: ff7c4ea11a05c8 ("VFS: add start_creating_killable() and start_removing_killable()")
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://patch.msgid.link/20251219024620.22880-3-bagasdotme@gmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Otherwise the slowpath can be taken by the caller, defeating the flag.
This regressed after calls to legitimize_links() started being
conditionally elided and stems from the routine always failing
after seeing the flag, regardless if there were any links.
In order to address both the bug and the weird semantics make it illegal
to call legitimize_links() with LOOKUP_CACHED and handle the problem at
the two callsites.
Fixes: 7c179096e77eca21 ("fs: add predicts based on nd->depth")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251220054023.142134-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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While knfsd offers combined exclusive create and open results to clients,
on some filesystems those results may not be atomic. This behavior can be
observed. For example, an open O_CREAT with mode 0 will succeed in creating
the file but unexpectedly return -EACCES from vfs_open().
Additionally reducing the number of remote RPC calls required for O_CREAT
on network filesystem provides a performance benefit in the open path.
Teach knfsd's helper dentry_create() to use atomic_open() for filesystems
that support it. The previously const @path is passed up to atomic_open()
and may be modified depending on whether an existing entry was found or if
the atomic_open() returned an error and consumed the passed-in dentry.
Signed-off-by: Benjamin Coddington <bcodding@hammerspace.com>
Link: https://patch.msgid.link/8e449bfb64ab055abb9fd82641a171531415a88c.1764259052.git.bcodding@hammerspace.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The next patch allows dentry_create() to call atomic_open(), but it does
not have fabricated nameidata. Let atomic_open() take a path instead.
Since atomic_open() currently takes a nameidata of which it only uses the
path and the flags, and flags are only used to update open_flags, then the
flag update can happen before calling atomic_open(). Then, only the path
needs be passed to atomic_open() rather than the whole nameidata. This
makes it easier for dentry_create() To call atomic_open().
Signed-off-by: Benjamin Coddington <bcodding@hammerspace.com>
Link: https://patch.msgid.link/e8c1d2ca28de4a972d37e78599502108148fe17d.1764259052.git.bcodding@hammerspace.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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To prepare knfsd's helper dentry_create(), move it to namei.c so that it
can access static functions within. Callers of dentry_create() can be
viewed as being mostly done with lookup, but still need to perform a few
final checks. In order to use atomic_open() we want dentry_create() to
be able to access:
- vfs_prepare_mode
- may_o_create
- atomic_open
.. all of which have static declarations.
Signed-off-by: Benjamin Coddington <bcodding@hammerspace.com>
Link: https://patch.msgid.link/42deec53a50e1676e5501f8f1e17967d47b83681.1764259052.git.bcodding@hammerspace.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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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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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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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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The primary consumer is link_path_walk(), calling walk_component() every
time which in turn calls step_into().
Inlining these saves overhead of 2 function calls per path component,
along with allowing the compiler to do better job optimizing them in place.
step_into() had absolutely atrocious assembly to facilitate the
slowpath. In order to lessen the burden at the callsite all the hard
work is moved into step_into_slowpath() and instead an inline-able
fastpath is implemented for rcu-walk.
The new fastpath is a stripped down step_into() RCU handling with a
d_managed() check from handle_mounts().
Benchmarked as follows on Sapphire Rapids:
1. the "before" was a kernel with not-yet-merged optimizations (notably
elision of calls to security_inode_permission() and marking ext4
inodes as not having acls as applicable)
2. "after" is the same + the prep patch + this patch
3. benchmark consists of issuing 205 calls to access(2) in a loop with
pathnames lifted out of gcc and the linker building real code, most
of which have several path components and 118 of which fail with
-ENOENT.
Result in terms of ops/s:
before: 21619
after: 22536 (+4%)
profile before:
20.25% [kernel] [k] __d_lookup_rcu
10.54% [kernel] [k] link_path_walk
10.22% [kernel] [k] entry_SYSCALL_64
6.50% libc.so.6 [.] __GI___access
6.35% [kernel] [k] strncpy_from_user
4.87% [kernel] [k] step_into
3.68% [kernel] [k] kmem_cache_alloc_noprof
2.88% [kernel] [k] walk_component
2.86% [kernel] [k] kmem_cache_free
2.14% [kernel] [k] set_root
2.08% [kernel] [k] lookup_fast
after:
23.38% [kernel] [k] __d_lookup_rcu
11.27% [kernel] [k] entry_SYSCALL_64
10.89% [kernel] [k] link_path_walk
7.00% libc.so.6 [.] __GI___access
6.88% [kernel] [k] strncpy_from_user
3.50% [kernel] [k] kmem_cache_alloc_noprof
2.01% [kernel] [k] kmem_cache_free
2.00% [kernel] [k] set_root
1.99% [kernel] [k] lookup_fast
1.81% [kernel] [k] do_syscall_64
1.69% [kernel] [k] entry_SYSCALL_64_safe_stack
While walk_component() and step_into() of course disappear from the
profile, the link_path_walk() barely gets more overhead despite the
inlining thanks to the fast path added and while completing more walks
per second.
I did not investigate why overhead grew a lot on __d_lookup_rcu().
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251120003803.2979978-2-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Symlink handling is already marked as unlikely and pushing out some of
it into pick_link() reduces register spillage on entry to step_into()
with gcc 14.2.
The compiler needed additional convincing that handle_mounts() is
unlikely to fail.
At the same time neither clang nor gcc could be convinced to tail-call
into pick_link().
While pick_link() takes an address of stack-based object as an argument
(which definitely prevents the optimization), splitting it into separate
<dentry, mount> tuple did not help. The issue persists even when
compiled without stack protector. As such nothing was done about this
for the time being to not grow the diff.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251120003803.2979978-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Otherwise it gets inlined notably in walk_component(), which convinces
the compiler to push/pop additional registers in the fast path to
accomodate existence of the inlined version.
Shortens the fast path of that routine from 87 to 71 bytes.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251119144930.2911698-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Stats from nd->depth usage during the venerable kernel build collected like so:
bpftrace -e 'kprobe:terminate_walk,kprobe:walk_component,kprobe:legitimize_links
{ @[probe] = lhist(((struct nameidata *)arg0)->depth, 0, 8, 1); }'
@[kprobe:legitimize_links]:
[0, 1) 6554906 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[1, 2) 3534 | |
@[kprobe:terminate_walk]:
[0, 1) 12153664 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
@[kprobe:walk_component]:
[0, 1) 53075749 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[1, 2) 971421 | |
[2, 3) 84946 | |
Additionally a custom probe was added for depth within link_path_walk():
bpftrace -e 'kprobe:link_path_walk_probe { @[probe] = lhist(arg0, 0, 8, 1); }'
@[kprobe:link_path_walk_probe]:
[0, 1) 7528231 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[1, 2) 407905 |@@ |
Given these results:
1. terminate_walk() is called towards the end of the lookup and in this
test it never had any links to clean up.
2. legitimize_links() is also called towards the end of lookup and most
of the time there s 0 depth. Patch consumers to avoid calling into it
in that case.
3. walk_component() is typically called with WALK_MORE and zero depth,
checked in that order. Check depth first and predict it is 0.
4. link_path_walk() also does not deal with a symlink most of the time
when !*name
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251119142954.2909394-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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vfs_mkdir() already drops the reference to the dentry on failure but it
leaves the parent locked.
This complicates end_creating() which needs to unlock the parent even
though the dentry is no longer available.
If we change vfs_mkdir() to unlock on failure as well as releasing the
dentry, we can remove the "parent" arg from end_creating() and simplify
the rules for calling it.
Note that cachefiles_get_directory() can choose to substitute an error
instead of actually calling vfs_mkdir(), for fault injection. In that
case it needs to call end_creating(), just as vfs_mkdir() now does on
error.
ovl_create_real() will now unlock on error. So the conditional
end_creating() after the call is removed, and end_creating() is called
internally on error.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-15-neilb@ownmail.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
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This requires the addition of start_creating_dentry() which is given the
dentry which has already been found, and asks for it to be locked and
its parent validated.
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/20251113002050.676694-14-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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A few callers want to lock for a rename and already have both dentries.
Also debugfs does want to perform a lookup but doesn't want permission
checking, so start_renaming_dentry() cannot be used.
This patch introduces start_renaming_two_dentries() which is given both
dentries. debugfs performs one lookup itself. As it will only continue
with a negative dentry and as those cannot be renamed or unlinked, it is
safe to do the lookup before getting the rename locks.
overlayfs uses start_renaming_two_dentries() in three places and selinux
uses it twice in sel_make_policy_nodes().
In sel_make_policy_nodes() we now lock for rename twice instead of just
once so the combined operation is no longer atomic w.r.t the parent
directory locks. As selinux_state.policy_mutex is held across the whole
operation this does not open up any interesting races.
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/20251113002050.676694-13-neilb@ownmail.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
Several callers perform a rename on a dentry they already have, and only
require lookup for the target name. This includes smb/server and a few
different places in overlayfs.
start_renaming_dentry() performs the required lookup and takes the
required lock using lock_rename_child()
It is used in three places in overlayfs and in ksmbd_vfs_rename().
In the ksmbd case, the parent of the source is not important - the
source must be renamed from wherever it is. So start_renaming_dentry()
allows rd->old_parent to be NULL and only checks it if it is non-NULL.
On success rd->old_parent will be the parent of old_dentry with an extra
reference taken. Other start_renaming function also now take the extra
reference and end_renaming() now drops this reference as well.
ovl_lookup_temp(), ovl_parent_lock(), and ovl_parent_unlock() are
all removed as they are no longer needed.
OVL_TEMPNAME_SIZE and ovl_tempname() are now declared in overlayfs.h so
that ovl_check_rename_whiteout() can access them.
ovl_copy_up_workdir() now always cleans up on error.
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
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/20251113002050.676694-12-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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|
start_renaming() combines name lookup and locking to prepare for rename.
It is used when two names need to be looked up as in nfsd and overlayfs -
cases where one or both dentries are already available will be handled
separately.
__start_renaming() avoids the inode_permission check and hash
calculation and is suitable after filename_parentat() in do_renameat2().
It subsumes quite a bit of code from that function.
start_renaming() does calculate the hash and check X permission and is
suitable elsewhere:
- nfsd_rename()
- ovl_rename()
In ovl, ovl_do_rename_rd() is factored out of ovl_do_rename(), which
itself will be gone by the end of the series.
Acked-by: Chuck Lever <chuck.lever@oracle.com> (for nfsd parts)
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: NeilBrown <neil@brown.name>
--
Changes since v3:
- added missig dput() in ovl_rename when "whiteout" is not-NULL.
Changes since v2:
- in __start_renaming() some label have been renamed, and err
is always set before a "goto out_foo" rather than passing the
error in a dentry*.
- ovl_do_rename() changed to call the new ovl_do_rename_rd() rather
than keeping duplicate code
- code around ovl_cleanup() call in ovl_rename() restructured.
Link: https://patch.msgid.link/20251113002050.676694-11-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
|
These are similar to start_creating() and start_removing(), but allow a
fatal signal to abort waiting for the lock.
They are used in btrfs for subvol creation and removal.
btrfs_may_create() no longer needs IS_DEADDIR() and
start_creating_killable() includes that check.
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/20251113002050.676694-10-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
