kernel/linux.git/fs/autofs, branch v6.18.22

new helper: set_default_d_op()

2025-06-11T02:21:16+00:00

... to be used instead of manually assigning to ->s_d_op. All in-tree filesystem converted (and field itself is renamed, so any out-of-tree ones in need of conversion will be caught by compiler). Reviewed-by: Christian Brauner Signed-off-by: Al Viro

VFS: rename lookup_one_len family to lookup_noperm and remove permission check

2025-04-08T09:24:36+00:00

The lookup_one_len family of functions is (now) only used internally by a filesystem on itself either - in a context where permission checking is irrelevant such as by a virtual filesystem populating itself, or xfs accessing its ORPHANAGE or dquota accessing the quota file; or - in a context where a permission check (MAY_EXEC on the parent) has just been performed such as a network filesystem finding in "silly-rename" file in the same directory. This is also the context after the _parentat() functions where currently lookup_one_qstr_excl() is used. So the permission check is pointless. The name "one_len" is unhelpful in understanding the purpose of these functions and should be changed. Most of the callers pass the len as "strlen()" so using a qstr and QSTR() can simplify the code. This patch renames these functions (include lookup_positive_unlocked() which is part of the family despite the name) to have a name based on "lookup_noperm". They are changed to receive a 'struct qstr' instead of separate name and len. In a few cases the use of QSTR() results in a new call to strlen(). try_lookup_noperm() takes a pointer to a qstr instead of the whole qstr. This is consistent with d_hash_and_lookup() (which is nearly identical) and useful for lookup_noperm_unlocked(). The new lookup_noperm_common() doesn't take a qstr yet. That will be tidied up in a subsequent patch. Signed-off-by: NeilBrown Link: https://lore.kernel.org/r/20250319031545.2999807-5-neil@brown.name Signed-off-by: Christian Brauner

Merge tag 'vfs-6.15-rc1.async.dir' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-03-24T17:47:14+00:00

Pull vfs async dir updates from Christian Brauner: "This contains cleanups that fell out of the work from async directory handling: - Change kern_path_locked() and user_path_locked_at() to never return a negative dentry. This simplifies the usability of these helpers in various places - Drop d_exact_alias() from the remaining place in NFS where it is still used. This also allows us to drop the d_exact_alias() helper completely - Drop an unnecessary call to fh_update() from nfsd_create_locked() - Change i_op->mkdir() to return a struct dentry Change vfs_mkdir() to return a dentry provided by the filesystems which is hashed and positive. This allows us to reduce the number of cases where the resulting dentry is not positive to very few cases. The code in these places becomes simpler and easier to understand. - Repack DENTRY_* and LOOKUP_* flags" * tag 'vfs-6.15-rc1.async.dir' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: doc: fix inline emphasis warning VFS: Change vfs_mkdir() to return the dentry. nfs: change mkdir inode_operation to return alternate dentry if needed. fuse: return correct dentry for ->mkdir ceph: return the correct dentry on mkdir hostfs: store inode in dentry after mkdir if possible. Change inode_operations.mkdir to return struct dentry * nfsd: drop fh_update() from S_IFDIR branch of nfsd_create_locked() nfs/vfs: discard d_exact_alias() VFS: add common error checks to lookup_one_qstr_excl() VFS: change kern_path_locked() and user_path_locked_at() to never return negative dentry VFS: repack LOOKUP_ bit flags. VFS: repack DENTRY_ flags.

Merge tag 'vfs-6.15-rc1.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-03-24T16:34:10+00:00

Pull vfs mount updates from Christian Brauner: - Mount notifications The day has come where we finally provide a new api to listen for mount topology changes outside of /proc//mountinfo. A mount namespace file descriptor can be supplied and registered with fanotify to listen for mount topology changes. Currently notifications for mount, umount and moving mounts are generated. The generated notification record contains the unique mount id of the mount. The listmount() and statmount() api can be used to query detailed information about the mount using the received unique mount id. This allows userspace to figure out exactly how the mount topology changed without having to generating diffs of /proc//mountinfo in userspace. - Support O_PATH file descriptors with FSCONFIG_SET_FD in the new mount api - Support detached mounts in overlayfs Since last cycle we support specifying overlayfs layers via file descriptors. However, we don't allow detached mounts which means userspace cannot user file descriptors received via open_tree(OPEN_TREE_CLONE) and fsmount() directly. They have to attach them to a mount namespace via move_mount() first. This is cumbersome and means they have to undo mounts via umount(). Allow them to directly use detached mounts. - Allow to retrieve idmappings with statmount Currently it isn't possible to figure out what idmapping has been attached to an idmapped mount. Add an extension to statmount() which allows to read the idmapping from the mount. - Allow creating idmapped mounts from mounts that are already idmapped So far it isn't possible to allow the creation of idmapped mounts from already idmapped mounts as this has significant lifetime implications. Make the creation of idmapped mounts atomic by allow to pass struct mount_attr together with the open_tree_attr() system call allowing to solve these issues without complicating VFS lookup in any way. The system call has in general the benefit that creating a detached mount and applying mount attributes to it becomes an atomic operation for userspace. - Add a way to query statmount() for supported options Allow userspace to query which mount information can be retrieved through statmount(). - Allow superblock owners to force unmount * tag 'vfs-6.15-rc1.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (21 commits) umount: Allow superblock owners to force umount selftests: add tests for mount notification selinux: add FILE__WATCH_MOUNTNS samples/vfs: fix printf format string for size_t fs: allow changing idmappings fs: add kflags member to struct mount_kattr fs: add open_tree_attr() fs: add copy_mount_setattr() helper fs: add vfs_open_tree() helper statmount: add a new supported_mask field samples/vfs: add STATMOUNT_MNT_{G,U}IDMAP selftests: add tests for using detached mount with overlayfs samples/vfs: check whether flag was raised statmount: allow to retrieve idmappings uidgid: add map_id_range_up() fs: allow detached mounts in clone_private_mount() selftests/overlayfs: test specifying layers as O_PATH file descriptors fs: support O_PATH fds with FSCONFIG_SET_FD vfs: add notifications for mount attach and detach fanotify: notify on mount attach and detach ...

VFS/autofs: try_lookup_one_len() does not need any locks

2025-03-18T14:34:27+00:00

try_lookup_one_len() is identical to lookup_one_unlocked() except that it doesn't include the call to lookup_slow(). The latter doesn't need the inode to be locked, so the former cannot either. So fix the documentation, remove the WARN_ON and fix the only caller to not take the lock. Signed-off-by: NeilBrown Link: https://lore.kernel.org/r/174190517441.9342.5956460781380903128@noble.neil.brown.name Signed-off-by: Christian Brauner

Change inode_operations.mkdir to return struct dentry *

2025-02-27T19:00:17+00:00

Some filesystems, such as NFS, cifs, ceph, and fuse, do not have complete control of sequencing on the actual filesystem (e.g. on a different server) and may find that the inode created for a mkdir request already exists in the icache and dcache by the time the mkdir request returns. For example, if the filesystem is mounted twice the directory could be visible on the other mount before it is on the original mount, and a pair of name_to_handle_at(), open_by_handle_at() calls could instantiate the directory inode with an IS_ROOT() dentry before the first mkdir returns. This means that the dentry passed to ->mkdir() may not be the one that is associated with the inode after the ->mkdir() completes. Some callers need to interact with the inode after the ->mkdir completes and they currently need to perform a lookup in the (rare) case that the dentry is no longer hashed. This lookup-after-mkdir requires that the directory remains locked to avoid races. Planned future patches to lock the dentry rather than the directory will mean that this lookup cannot be performed atomically with the mkdir. To remove this barrier, this patch changes ->mkdir to return the resulting dentry if it is different from the one passed in. Possible returns are: NULL - the directory was created and no other dentry was used ERR_PTR() - an error occurred non-NULL - this other dentry was spliced in This patch only changes file-systems to return "ERR_PTR(err)" instead of "err" or equivalent transformations. Subsequent patches will make further changes to some file-systems to return a correct dentry. Not all filesystems reliably result in a positive hashed dentry: - NFS, cifs, hostfs will sometimes need to perform a lookup of the name to get inode information. Races could result in this returning something different. Note that this lookup is non-atomic which is what we are trying to avoid. Placing the lookup in filesystem code means it only happens when the filesystem has no other option. - kernfs and tracefs leave the dentry negative and the ->revalidate operation ensures that lookup will be called to correctly populate the dentry. This could be fixed but I don't think it is important to any of the users of vfs_mkdir() which look at the dentry. The recommendation to use d_drop();d_splice_alias() is ugly but fits with current practice. A planned future patch will change this. Reviewed-by: Jeff Layton Reviewed-by: Jan Kara Signed-off-by: NeilBrown Link: https://lore.kernel.org/r/20250227013949.536172-2-neilb@suse.de Signed-off-by: Christian Brauner

fs: support O_PATH fds with FSCONFIG_SET_FD

2025-02-12T09:02:10+00:00

Let FSCONFIG_SET_FD handle O_PATH file descriptors. This is particularly useful in the context of overlayfs where layers can be specified via file descriptors instead of paths. But userspace must currently use non-O_PATH file desriptors which is often pointless especially if the file descriptors have been created via open_tree(OPEN_TREE_CLONE). Link: https://lore.kernel.org/r/20250210-work-overlayfs-v2-1-ed2a949b674b@kernel.org Fixes: a08557d19ef41 ("ovl: specify layers via file descriptors") Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner

autofs: fix thinko in validate_dev_ioctl()

2024-10-28T12:16:56+00:00

I was so sure the per-dentry expire timeout patch worked ok but my testing was flawed. In validate_dev_ioctl() the check for ioctl AUTOFS_DEV_IOCTL_TIMEOUT_CMD should use the ioctl number not the passed in ioctl command. Fixes: 433f9d76a010 ("autofs: add per dentry expire timeout") Cc: # mainline only Signed-off-by: Ian Kent Link: https://lore.kernel.org/r/20241027224732.5507-1-raven@themaw.net Signed-off-by: Christian Brauner

autofs: add per dentry expire timeout

2024-08-30T06:22:36+00:00

Add ability to set per-dentry mount expire timeout to autofs. There are two fairly well known automounter map formats, the autofs format and the amd format (more or less System V and Berkley). Some time ago Linux autofs added an amd map format parser that implemented a fair amount of the amd functionality. This was done within the autofs infrastructure and some functionality wasn't implemented because it either didn't make sense or required extra kernel changes. The idea was to restrict changes to be within the existing autofs functionality as much as possible and leave changes with a wider scope to be considered later. One of these changes is implementing the amd options: 1) "unmount", expire this mount according to a timeout (same as the current autofs default). 2) "nounmount", don't expire this mount (same as setting the autofs timeout to 0 except only for this specific mount) . 3) "utimeout=", expire this mount using the specified timeout (again same as setting the autofs timeout but only for this mount). To implement these options per-dentry expire timeouts need to be implemented for autofs indirect mounts. This is because all map keys (mounts) for autofs indirect mounts use an expire timeout stored in the autofs mount super block info. structure and all indirect mounts use the same expire timeout. Now I have a request to add the "nounmount" option so I need to add the per-dentry expire handling to the kernel implementation to do this. The implementation uses the trailing path component to identify the mount (and is also used as the autofs map key) which is passed in the autofs_dev_ioctl structure path field. The expire timeout is passed in autofs_dev_ioctl timeout field (well, of the timeout union). If the passed in timeout is equal to -1 the per-dentry timeout and flag are cleared providing for the "unmount" option. If the timeout is greater than or equal to 0 the timeout is set to the value and the flag is also set. If the dentry timeout is 0 the dentry will not expire by timeout which enables the implementation of the "nounmount" option for the specific mount. When the dentry timeout is greater than zero it allows for the implementation of the "utimeout=" option. Signed-off-by: Ian Kent Link: https://lore.kernel.org/r/20240814090231.963520-1-raven@themaw.net Signed-off-by: Christian Brauner

autofs: fix missing fput for FSCONFIG_SET_FD

2024-08-19T11:45:03+00:00

If you pass an fd using FSCONFIG_SET_FD, autofs_parse_fd() "steals" the param->file and so the fs_context infrastructure will not do fput() for us. Fixes: e6ec453bd0f0 ("autofs: convert autofs to use the new mount api") Signed-off-by: Aleksa Sarai Link: https://lore.kernel.org/r/20240731-fsconfig-fsparam_fd-fixes-v2-1-e7c472224417@cyphar.com Signed-off-by: Christian Brauner