kernel/linux.git/fs/overlayfs, branch v6.18.21

ovl: fix wrong detection of 32bit inode numbers

2026-04-02T11:23:21+00:00

commit 53a7c171e9dd833f0a96b545adcb89bd57387239 upstream. The implicit FILEID_INO32_GEN encoder was changed to be explicit, so we need to fix the detection. When mounting overlayfs with upperdir and lowerdir on different ext4 filesystems, the expected kmsg log is: overlayfs: "xino" feature enabled using 32 upper inode bits. But instead, since the regressing commit, the kmsg log was: overlayfs: "xino" feature enabled using 2 upper inode bits. Fixes: e21fc2038c1b9 ("exportfs: make ->encode_fh() a mandatory method for NFS export") Cc: stable@vger.kernel.org # v6.7+ Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman

ovl: make fsync after metadata copy-up opt-in mount option

2026-04-02T11:23:21+00:00

commit 1f6ee9be92f8df85a8c9a5a78c20fd39c0c21a95 upstream. Commit 7d6899fb69d25 ("ovl: fsync after metadata copy-up") was done to fix durability of overlayfs copy up on an upper filesystem which does not enforce ordering on storing of metadata changes (e.g. ubifs). In an earlier revision of the regressing commit by Lei Lv, the metadata fsync behavior was opt-in via a new "fsync=strict" mount option. We were hoping that the opt-in mount option could be avoided, so the change was only made to depend on metacopy=off, in the hope of not hurting performance of metadata heavy workloads, which are more likely to be using metacopy=on. This hope was proven wrong by a performance regression report from Google COS workload after upgrade to kernel 6.12. This is an adaptation of Lei's original "fsync=strict" mount option to the existing upstream code. The new mount option is mutually exclusive with the "volatile" mount option, so the latter is now an alias to the "fsync=volatile" mount option. Reported-by: Chenglong Tang Closes: https://lore.kernel.org/linux-unionfs/CAOdxtTadAFH01Vui1FvWfcmQ8jH1O45owTzUcpYbNvBxnLeM7Q@mail.gmail.com/ Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxgKC1SgjMWre=fUb00v8rxtd6sQi-S+dxR8oDzAuiGu8g@mail.gmail.com/ Fixes: 7d6899fb69d25 ("ovl: fsync after metadata copy-up") Depends: 50e638beb67e0 ("ovl: Use str_on_off() helper in ovl_show_options()") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Fei Lv Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman

ovl: Fix uninit-value in ovl_fill_real

2026-02-26T22:59:34+00:00

[ Upstream commit 1992330d90dd766fcf1730fd7bf2d6af65370ac4 ] Syzbot reported a KMSAN uninit-value issue in ovl_fill_real. This iusse's call chain is: __do_sys_getdents64() -> iterate_dir() ... -> ext4_readdir() -> fscrypt_fname_alloc_buffer() // alloc -> fscrypt_fname_disk_to_usr // write without tail '\0' -> dir_emit() -> ovl_fill_real() // read by strcmp() The string is used to store the decrypted directory entry name for an encrypted inode. As shown in the call chain, fscrypt_fname_disk_to_usr() write it without null-terminate. However, ovl_fill_real() uses strcmp() to compare the name against "..", which assumes a null-terminated string and may trigger a KMSAN uninit-value warning when the buffer tail contains uninit data. Reported-by: syzbot+d130f98b2c265fae5297@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d130f98b2c265fae5297 Fixes: 4edb83bb1041 ("ovl: constant d_ino for non-merge dirs") Signed-off-by: Qing Wang Signed-off-by: Amir Goldstein Link: https://patch.msgid.link/20260128132406.23768-2-amir73il@gmail.com Acked-by: Miklos Szeredi Reviewed-by: Eric Biggers Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

ovl: fail ovl_lock_rename_workdir() if either target is unhashed

2025-11-28T09:42:32+00:00

As well as checking that the parent hasn't changed after getting the lock we need to check that the dentry hasn't been unhashed. Otherwise we might try to rename something that has been removed. Reported-by: syzbot+bfc9a0ccf0de47d04e8c@syzkaller.appspotmail.com Fixes: d2c995581c7c ("ovl: Call ovl_create_temp() without lock held.") Signed-off-by: NeilBrown Link: https://patch.msgid.link/176429295510.634289.1552337113663461690@noble.neil.brown.name Tested-by: syzbot+bfc9a0ccf0de47d04e8c@syzkaller.appspotmail.com Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner

ovl: remove redundant IOCB_DIO_CALLER_COMP clearing

2025-10-10T12:02:47+00:00

The backing_file_write_iter() function, which is called immediately after this code, already contains identical logic to clear the IOCB_DIO_CALLER_COMP flag along with the same explanatory comment. There is no need to duplicate this operation in the overlayfs code. Signed-off-by: Seong-Gwang Heo Fixes: a6293b3e285c ("fs: factor out backing_file_{read,write}_iter() helpers") Acked-by: Miklos Szeredi Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner

Revert "fs: make vfs_fileattr_[get|set] return -EOPNOTSUPP"

2025-10-10T11:44:03+00:00

This reverts commit 474b155adf3927d2c944423045757b54aa1ca4de. This patch caused regression in ioctl_setflags(). Underlying filesystems use EOPNOTSUPP to indicate that flag is not supported. This error is also gets converted in ioctl_setflags(). Therefore, for unsupported flags error changed from EOPNOSUPP to ENOIOCTLCMD. Link: https://lore.kernel.org/linux-xfs/a622643f-1585-40b0-9441-cf7ece176e83@kernel.org/ Signed-off-by: Andrey Albershteyn Signed-off-by: Christian Brauner

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

2025-10-03T23:32:36+00:00

Pull file->f_path constification from Al Viro: "Only one thing was modifying ->f_path of an opened file - acct(2). Massaging that away and constifying a bunch of struct path * arguments in functions that might be given &file->f_path ends up with the situation where we can turn ->f_path into an anon union of const struct path f_path and struct path __f_path, the latter modified only in a few places in fs/{file_table,open,namei}.c, all for struct file instances that are yet to be opened" * tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (23 commits) Have cc(1) catch attempts to modify ->f_path kernel/acct.c: saner struct file treatment configfs:get_target() - release path as soon as we grab configfs_item reference apparmor/af_unix: constify struct path * arguments ovl_is_real_file: constify realpath argument ovl_sync_file(): constify path argument ovl_lower_dir(): constify path argument ovl_get_verity_digest(): constify path argument ovl_validate_verity(): constify {meta,data}path arguments ovl_ensure_verity_loaded(): constify datapath argument ksmbd_vfs_set_init_posix_acl(): constify path argument ksmbd_vfs_inherit_posix_acl(): constify path argument ksmbd_vfs_kern_path_unlock(): constify path argument ksmbd_vfs_path_lookup_locked(): root_share_path can be const struct path * check_export(): constify path argument export_operations->open(): constify path argument rqst_exp_get_by_name(): constify path argument nfs: constify path argument of __vfs_getattr() bpf...d_path(): constify path argument done_path_create(): constify path argument ...

Merge tag 'ovl-update-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs

2025-10-03T19:14:24+00:00

Pull overlayfs updates from Amir Goldstein: - Work by André Almeida to support case-insensitive overlayfs Underlying case-insensitive filesystems casefolding is per directory, but for overlayfs it is all-or-nothing. It supports layers where all directories are casefolded (with same encoding) or layers where no directories are casefolded. - A fix for a "bug" in Neil's ovl directory lock changes, which only manifested itself with casefold enabled layers which may return an unhashed negative dentry from lookup. * tag 'ovl-update-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs: ovl: make sure that ovl_create_real() returns a hashed dentry ovl: Support mounting case-insensitive enabled layers ovl: Check for casefold consistency when creating new dentries ovl: Add S_CASEFOLD as part of the inode flag to be copied ovl: Set case-insensitive dentry operations for ovl sb ovl: Ensure that all layers have the same encoding ovl: Create ovl_casefold() to support casefolded strncmp() ovl: Prepare for mounting case-insensitive enabled layers fs: Create sb_same_encoding() helper fs: Create sb_encoding() helper

Merge tag 'vfs-6.18-rc1.async' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-09-29T18:55:15+00:00

Pull vfs async directory updates from Christian Brauner: "This contains further preparatory changes for the asynchronous directory locking scheme: - Add lookup_one_positive_killable() which allows overlayfs to perform lookup that won't block on a fatal signal - Unify the mount idmap handling in struct renamedata as a rename can only happen within a single mount - Introduce kern_path_parent() for audit which sets the path to the parent and returns a dentry for the target without holding any locks on return - Rename kern_path_locked() as it is only used to prepare for the removal of an object from the filesystem: kern_path_locked() => start_removing_path() kern_path_create() => start_creating_path() user_path_create() => start_creating_user_path() user_path_locked_at() => start_removing_user_path_at() done_path_create() => end_creating_path() NA => end_removing_path()" * tag 'vfs-6.18-rc1.async' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: debugfs: rename start_creating() to debugfs_start_creating() VFS: rename kern_path_locked() and related functions. VFS/audit: introduce kern_path_parent() for audit VFS: unify old_mnt_idmap and new_mnt_idmap in renamedata VFS: discard err2 in filename_create() VFS/ovl: add lookup_one_positive_killable()

Merge tag 'vfs-6.18-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-09-29T16:03:07+00:00

Pull misc vfs updates from Christian Brauner: "This contains the usual selections of misc updates for this cycle. Features: - Add "initramfs_options" parameter to set initramfs mount options. This allows to add specific mount options to the rootfs to e.g., limit the memory size - Add RWF_NOSIGNAL flag for pwritev2() Add RWF_NOSIGNAL flag for pwritev2. This flag prevents the SIGPIPE signal from being raised when writing on disconnected pipes or sockets. The flag is handled directly by the pipe filesystem and converted to the existing MSG_NOSIGNAL flag for sockets - Allow to pass pid namespace as procfs mount option Ever since the introduction of pid namespaces, procfs has had very implicit behaviour surrounding them (the pidns used by a procfs mount is auto-selected based on the mounting process's active pidns, and the pidns itself is basically hidden once the mount has been constructed) This implicit behaviour has historically meant that userspace was required to do some special dances in order to configure the pidns of a procfs mount as desired. Examples include: * In order to bypass the mnt_too_revealing() check, Kubernetes creates a procfs mount from an empty pidns so that user namespaced containers can be nested (without this, the nested containers would fail to mount procfs) But this requires forking off a helper process because you cannot just one-shot this using mount(2) * Container runtimes in general need to fork into a container before configuring its mounts, which can lead to security issues in the case of shared-pidns containers (a privileged process in the pidns can interact with your container runtime process) While SUID_DUMP_DISABLE and user namespaces make this less of an issue, the strict need for this due to a minor uAPI wart is kind of unfortunate Things would be much easier if there was a way for userspace to just specify the pidns they want. So this pull request contains changes to implement a new "pidns" argument which can be set using fsconfig(2): fsconfig(procfd, FSCONFIG_SET_FD, "pidns", NULL, nsfd); fsconfig(procfd, FSCONFIG_SET_STRING, "pidns", "/proc/self/ns/pid", 0); or classic mount(2) / mount(8): // mount -t proc -o pidns=/proc/self/ns/pid proc /tmp/proc mount("proc", "/tmp/proc", "proc", MS_..., "pidns=/proc/self/ns/pid"); Cleanups: - Remove the last references to EXPORT_OP_ASYNC_LOCK - Make file_remove_privs_flags() static - Remove redundant __GFP_NOWARN when GFP_NOWAIT is used - Use try_cmpxchg() in start_dir_add() - Use try_cmpxchg() in sb_init_done_wq() - Replace offsetof() with struct_size() in ioctl_file_dedupe_range() - Remove vfs_ioctl() export - Replace rwlock() with spinlock in epoll code as rwlock causes priority inversion on preempt rt kernels - Make ns_entries in fs/proc/namespaces const - Use a switch() statement() in init_special_inode() just like we do in may_open() - Use struct_size() in dir_add() in the initramfs code - Use str_plural() in rd_load_image() - Replace strcpy() with strscpy() in find_link() - Rename generic_delete_inode() to inode_just_drop() and generic_drop_inode() to inode_generic_drop() - Remove unused arguments from fcntl_{g,s}et_rw_hint() Fixes: - Document @name parameter for name_contains_dotdot() helper - Fix spelling mistake - Always return zero from replace_fd() instead of the file descriptor number - Limit the size for copy_file_range() in compat mode to prevent a signed overflow - Fix debugfs mount options not being applied - Verify the inode mode when loading it from disk in minixfs - Verify the inode mode when loading it from disk in cramfs - Don't trigger automounts with RESOLVE_NO_XDEV If openat2() was called with RESOLVE_NO_XDEV it didn't traverse through automounts, but could still trigger them - Add FL_RECLAIM flag to show_fl_flags() macro so it appears in tracepoints - Fix unused variable warning in rd_load_image() on s390 - Make INITRAMFS_PRESERVE_MTIME depend on BLK_DEV_INITRD - Use ns_capable_noaudit() when determining net sysctl permissions - Don't call path_put() under namespace semaphore in listmount() and statmount()" * tag 'vfs-6.18-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (38 commits) fcntl: trim arguments listmount: don't call path_put() under namespace semaphore statmount: don't call path_put() under namespace semaphore pid: use ns_capable_noaudit() when determining net sysctl permissions fs: rename generic_delete_inode() and generic_drop_inode() init: INITRAMFS_PRESERVE_MTIME should depend on BLK_DEV_INITRD initramfs: Replace strcpy() with strscpy() in find_link() initrd: Use str_plural() in rd_load_image() initramfs: Use struct_size() helper to improve dir_add() initrd: Fix unused variable warning in rd_load_image() on s390 fs: use the switch statement in init_special_inode() fs/proc/namespaces: make ns_entries const filelock: add FL_RECLAIM to show_fl_flags() macro eventpoll: Replace rwlock with spinlock selftests/proc: add tests for new pidns APIs procfs: add "pidns" mount option pidns: move is-ancestor logic to helper openat2: don't trigger automounts with RESOLVE_NO_XDEV namei: move cross-device check to __traverse_mounts namei: remove LOOKUP_NO_XDEV check from handle_mounts ...