kernel/git/stable/linux.git/fs/internal.h, branch master

Merge tag 'vfs-7.3-rc1.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-08-17T20:57:04+00:00

Pull vfs superblock updates from Christian Brauner: - Make it possible to share a block device between multiple filesystems. erofs can mount read-only blob devices shared between many superblocks, but because we only tracked a single superblock a freeze, thaw, removal or sync on such a device was never propagated to all the superblocks using it, and there was no way to find them. Add an efficient table to lookup all superblocks using a given block device. - A bunch of pre-existing fixes fell out of this work: A block-device freeze racing a btrfs device change could leave the whole filesystem stuck frozen. A bdev_freeze() issued by "dmsetup suspend" or an LVM snapshot resolves that holder to freeze the filesystem. and bdev_thaw() resolves it again to thaw. A freeze landing while btrfs is adding, removing or replacing a device freezes the filesystem. The membership change then drops that link. So the matching thaw could no longer find the superblock. Forbid freezing a device for the duration of a membership change, modelled on deny_write_access()/allow_write_access(). * tag 'vfs-7.3-rc1.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (24 commits) super: fix dying superblock warning messages block: reject block device inodes with i_rdev == 0 in lookup_bdev() selftests/filesystems: add ustat() coverage fs: look up the superblock via the device table in user_get_super() super: make fs_holder_ops private f2fs: open via dedicated fs bdev helpers erofs: open via dedicated fs bdev helpers fs: tolerate per-superblock freeze errors on shared devices fs: look up superblocks via the device table in fs_holder_ops ext4: open via dedicated fs bdev helpers btrfs: open via dedicated fs bdev helpers xfs: port to fs_bdev_file_open_by_path() fs: add dedicated block device open helpers for filesystems fs: maintain a global device-to-superblock table ocfs2: don't reset s_dev on dismount ext4: use anonymous devices for KUnit test superblocks fs, block: move blk_mode_t and fop_flags_t into super: take lock after last reference count super: convert s_count to refcount_t s_passive btrfs: deny freezing devices undergoing a replace ...

fs: support FD_FAILFS_ROOT in fchdir()

2026-07-27T15:17:59+00:00

Add a new file descriptor sentinel FD_FAILFS_ROOT following FD_PIDFS_ROOT and FD_NSFS_ROOT and teach fchdir() to accept it. A process calling fchdir(FD_FAILFS_ROOT) moves its working directory into failfs. Every AT_FDCWD-relative lookup afterwards fails with EOPNOTSUPP including "." and ".." and getcwd() reports the working directory as unreachable from the process root by returning a path prefixed with "(unreachable)". Lookups relative to explicit directory file descriptors are unaffected. The sentinel is the only way in. No privilege or gating is required. Setting the working directory to a directory in which every operation fails grants nothing and loses nothing that closing file descriptors couldn't lose. An unlinked working directory behaves the same way today modulo errno. The working directory also plays no role in confining ".." resolution so no boundary is weakened. Link: https://patch.msgid.link/20260724-work-failfs-v2-2-485dabbae185@kernel.org Signed-off-by: Christian Brauner (Amutable)

fs: add failfs

2026-07-27T15:17:59+00:00

nullfs provides a permanently empty and immutable directory. Lookups fail with ENOENT. The directory can be opened, read, stat, mounted upon. It behaves like nothing is there. Add its counterpart failfs where the semantics are not "there is nothing here" but "nothing is supported here". Every operation that reaches the filesystem fails with EOPNOTSUPP. Even statfs()/fstatfs() fail so the filesystem cannot be discovered through an fd to it. EOPNOTSUPP rather than a permission errno keeps that coherent. There is no permission model in which anything could ever be allowed and EACCES or EPERM would merely suggest that different credentials might succeed while EIO would suggest corruption. It also makes hitting the failfs boundary mostly quite dinstinguishable. A task anchoring its lookups at real directory file descriptors may be able to tell a failfs refusal from an ordinary permission failure. I wouldn't go so far as guaranteeing that but it should mostly work. No path lookup can open the root, not even with O_PATH. It is never reached by a lookup in a parent directory. The only way to a path-walk terminal at the root is a jump through a /proc//{root,cwd} magic link or by mountpoint traversal. The root also refuses ->d_weak_revalidate() which the VFS calls for jumped terminals. That covers the jump-based references too: an O_PATH open is refused, name_to_handle_at() cannot encode it into a file handle, and following a magic link into it fails. A plain readlink() of such a link still works and shows "failfs:/". There is a single instance of failfs mounted during early boot via kern_mount() making it logically distinct from every mount namespace. Since the mount is a member of no mount namespace mounting onto it fails. So nothing can ever be mounted on top of it. It cannot be cloned via OPEN_TREE_CLONE and it does not show up in statmount()/listmount() or /proc//mountinfo. The filesystem is not registered so it is not visible in /proc/filesystems and cannot be mounted from userspace. This lets tasks shed their filesystem state completely. A process with its root directory or working directory in failfs must anchor every path lookup at an explicit file descriptor or is doomed to fail any lookup. Absolute paths, absolute symlinks, and AT_FDCWD-relative lookups simply fail. Followup patches will expose it via a new FD_FAILFS_ROOT file descriptor sentinel understood by fchdir() and the new fchroot() system call. Link: https://patch.msgid.link/20260724-work-failfs-v2-1-485dabbae185@kernel.org Signed-off-by: Christian Brauner (Amutable)

fs: maintain a global device-to-superblock table

2026-06-29T08:31:52+00:00

fs_holder_ops recovers the owning superblock from bdev->bd_holder, which forces the holder to be exactly one superblock and prevents several superblocks from sharing one block device. That's what erofs is doing. As a first step introduce a global dev_t-keyed rhltable mapping each device to the superblock(s) using it. The entry is preallocated in alloc_super() and registered under sb->s_dev by the set callback through set_anon_super() and set_bdev_super(), the two helpers every set callback assigns s_dev through. Registration is the final fallible act of a set callback, so an insert failure unwinds through sget_fc()'s existing set-failure path: the fs_context keeps ownership of s_fs_info and the callers' error paths stay correct. set_anon_super() releases the anonymous dev it allocated when registration fails. Unwinding through deactivate_locked_super() instead would run kill_sb() and free s_fs_info behind the caller's back: nfs and ceph free that object through a local pointer when sget_fc() fails and would double-free. The superblock stashes the entry in sb->s_super_dev and kill_super_notify() drops the claim through it, so teardown doesn't depend on s_dev staying stable; an entry that was never registered is freed together with the superblock in destroy_super_work(). Each table entry holds a passive reference (s_passive) on its superblock, so the struct stays valid for as long as the entry is reachable. Entries are claim-counted through sd_ref: additional claims on the same (device, superblock) pair share the entry, and the unlink is deferred to the last put, so a later iteration cursor never resumes from a removed node. The table is initialized from mnt_init(): the first superblocks (the tmpfs shm mount and rootfs) are created from start_kernel() long before any initcall runs, so an initcall would be too late. The table has no readers yet; the fs_holder_ops callbacks are switched over once all devices a filesystem claims are registered. Link: https://patch.msgid.link/20260616-work-super-bdev_holder_global-v2-7-7df6b864028e@kernel.org Reviewed-by: Jan Kara Signed-off-by: Christian Brauner (Amutable)

fuse: invalidate page cache after DIO and async DIO writes

2026-06-15T12:06:20+00:00

This fixe does page cache invalidation after DIO and async DIO writes for both O_DIRECT and FOPEN_DIRECT_IO cases. Commit b359af8275a9 ("fuse: Invalidate the page cache after FOPEN_DIRECT_IO write") fixed xfstests generic/209 for DIO writes in the FOPEN_DIRECT_IO path. DIO writes without FOPEN_DIRECT_IO are already handled by generic_file_direct_write(). However, async DIO writes (xfstests generic/451) remain unhandled. After this fix: - Async write with FUSE_ASYNC_DIO: invalidate in fuse_aio_invalidate_worker() - Otherwise (Sync or async write without FUSE_ASYNC_DIO): - With FOPEN_DIRECT_IO: invalidate in fuse_direct_write_iter() - Without FOPEN_DIRECT_IO: invalidate in generic_file_direct_write() Workqueue is required for async write invalidation to prevent deadlock: calling it directly in the I/O end routine (which is in fuse worker thread context) can block on a folio lock held by a buffered I/O thread waiting for the same fuse worker thread. Co-developed-by: Jingbo Xu Signed-off-by: Jingbo Xu Signed-off-by: Cheng Ding Reviewed-by: Jingbo Xu Signed-off-by: Miklos Szeredi

Merge tag 'lsm-pr-20260410' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

2026-04-13T22:17:28+00:00

Pull LSM updates from Paul Moore: "We only have five patches in the LSM tree, but three of the five are for an important bugfix relating to overlayfs and the mmap() and mprotect() access controls for LSMs. Highlights below: - Fix problems with the mmap() and mprotect() LSM hooks on overlayfs As we are dealing with problems both in mmap() and mprotect() there are essentially two components to this fix, spread across three patches with all marked for stable. The simplest portion of the fix is the creation of a new LSM hook, security_mmap_backing_file(), that is used to enforce LSM mmap() access controls on backing files in the stacked/overlayfs case. The existing security_mmap_file() does not have visibility past the user file. You can see from the associated SELinux hook callback the code is fairly straightforward. The mprotect() fix is a bit more complicated as there is no way in the mprotect() code path to inspect both the user and backing files, and bolting on a second file reference to vm_area_struct wasn't really an option. The solution taken here adds a LSM security blob and associated hooks to the backing_file struct that LSMs can use to capture and store relevant information from the user file. While the necessary SELinux information is relatively small, a single u32, I expect other LSMs to require more than that, and a dedicated backing_file LSM blob provides a storage mechanism without negatively impacting other filesystems. I want to note that other LSMs beyond SELinux have been involved in the discussion of the fixes presented here and they are working on their own related changes using these new hooks, but due to other issues those patches will be coming at a later date. - Use kstrdup_const()/kfree_const() for securityfs symlink targets - Resolve a handful of kernel-doc warnings in cred.h" * tag 'lsm-pr-20260410' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm: selinux: fix overlayfs mmap() and mprotect() access checks lsm: add backing_file LSM hooks fs: prepare for adding LSM blob to backing_file securityfs: use kstrdup_const() to manage symlink targets cred: fix kernel-doc warnings in cred.h

lsm: add backing_file LSM hooks

2026-04-03T20:53:50+00:00

Stacked filesystems such as overlayfs do not currently provide the necessary mechanisms for LSMs to properly enforce access controls on the mmap() and mprotect() operations. In order to resolve this gap, a LSM security blob is being added to the backing_file struct and the following new LSM hooks are being created: security_backing_file_alloc() security_backing_file_free() security_mmap_backing_file() The first two hooks are to manage the lifecycle of the LSM security blob in the backing_file struct, while the third provides a new mmap() access control point for the underlying backing file. It is also expected that LSMs will likely want to update their security_file_mprotect() callback to address issues with their mprotect() controls, but that does not require a change to the security_file_mprotect() LSM hook. There are a three other small changes to support these new LSM hooks: * Pass the user file associated with a backing file down to alloc_empty_backing_file() so it can be included in the security_backing_file_alloc() hook. * Add getter and setter functions for the backing_file struct LSM blob as the backing_file struct remains private to fs/file_table.c. * Constify the file struct field in the LSM common_audit_data struct to better support LSMs that need to pass a const file struct pointer into the common LSM audit code. Thanks to Arnd Bergmann for identifying the missing EXPORT_SYMBOL_GPL() and supplying a fixup. Cc: stable@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org Cc: linux-unionfs@vger.kernel.org Cc: linux-erofs@lists.ozlabs.org Reviewed-by: Amir Goldstein Reviewed-by: Serge Hallyn Reviewed-by: Christian Brauner Signed-off-by: Paul Moore

fs: pass on FTRUNCATE_* flags to do_truncate

2026-03-23T11:41:57+00:00

Pass the flags one level down to replace the somewhat confusing small argument, and clean up do_truncate as a result. Signed-off-by: Christoph Hellwig Link: https://patch.msgid.link/20260323070205.2939118-3-hch@lst.de Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

fs: fix archiecture-specific compat_ftruncate64

2026-03-23T11:41:57+00:00

The "small" argument to do_sys_ftruncate indicates if > 32-bit size should be reject, but all the arch-specific compat ftruncate64 implementations get this wrong. Merge do_sys_ftruncate and ksys_ftruncate, replace the integer as boolean small flag with a descriptive one about LFS semantics, and use it correctly in the architecture-specific ftruncate64 implementations. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: 3dd681d944f6 ("arm64: 32-bit (compat) applications support") Signed-off-by: Christoph Hellwig Link: https://patch.msgid.link/20260323070205.2939118-2-hch@lst.de Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

Merge tag 'pull-filename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2026-02-10T00:58:28+00:00

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) ...