Linux kernel stable tree (mirror) https://git.radix-linux.su/kernel/linux.git/atom?h=v6.19.11 2025-12-02T00:13:46+00:00 2025-12-02T00:13:46+00:00 Linus Torvalds torvalds@linux-foundation.org 2025-12-02T00:13:46+00:00 urn:sha1:a8058f8442df3150fa58154672f4a62a13e833e5 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() 2025-11-14T12:15:58+00:00 NeilBrown neil@brown.name 2025-11-13T00:18:38+00:00 urn:sha1:cf296b294c3bd8f7db229060efe677dfd49e46b6 Occasionally the caller of end_creating() wants to keep using the dentry. Rather then requiring them to dget() the dentry (when not an error) before calling end_creating(), provide end_creating_keep() which does this. cachefiles and overlayfs make use of this. 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/20251113002050.676694-16-neilb@ownmail.net Tested-by: syzbot@syzkaller.appspotmail.com Signed-off-by: Christian Brauner <brauner@kernel.org> 2025-11-14T12:15:58+00:00 NeilBrown neil@brown.name 2025-11-13T00:18:37+00:00 urn:sha1:fe497f0759e0efb949f9480911d00b6045c21f50 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> 2025-11-14T12:15:58+00:00 NeilBrown neil@brown.name 2025-11-13T00:18:36+00:00 urn:sha1:f046fbb4d81d1b0c4a169707411e3cd540c03354 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> 2025-11-14T12:15:58+00:00 NeilBrown neil@brown.name 2025-11-13T00:18:35+00:00 urn:sha1:833d2b3a072f7ff6005bf84c065c7cbda81a8aaa 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> 2025-11-14T12:15:57+00:00 NeilBrown neil@brown.name 2025-11-13T00:18:34+00:00 urn:sha1:ac50950ca143fd637dec4f7457a9162e1a4344e8 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> 2025-11-14T12:15:57+00:00 NeilBrown neil@brown.name 2025-11-13T00:18:33+00:00 urn:sha1:5c8752729970cc2323ba86817254749f7f21f163 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> 2025-11-14T12:15:57+00:00 NeilBrown neil@brown.name 2025-11-13T00:18:32+00:00 urn:sha1:ff7c4ea11a05c886f018fff4a4d4f4d68d951e25 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> 2025-11-14T12:15:57+00:00 NeilBrown neil@brown.name 2025-11-13T00:18:31+00:00 urn:sha1:7bb1eb45e43c4730cbc5a48b9e9295049fccdacb start_removing_dentry() is similar to start_removing() but instead of providing a name for lookup, the target dentry is given. start_removing_dentry() checks that the dentry is still hashed and in the parent, and if so it locks and increases the refcount so that end_removing() can be used to finish the operation. This is used in cachefiles, overlayfs, smb/server, and apparmor. There will be other users including ecryptfs. As start_removing_dentry() takes an extra reference to the dentry (to be put by end_removing()), there is no need to explicitly take an extra reference to stop d_delete() from using dentry_unlink_inode() to negate the dentry - as in cachefiles_delete_object(), and ksmbd_vfs_unlink(). cachefiles_bury_object() now gets an extra ref to the victim, which is drops. As it includes the needed end_removing() calls, the caller doesn't need them. Reviewed-by: Amir Goldstein <amir73il@gmail.com> Reviewed-by: Namjae Jeon <linkinjeon@kernel.org> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: NeilBrown <neil@brown.name> Link: https://patch.msgid.link/20251113002050.676694-9-neilb@ownmail.net Signed-off-by: Christian Brauner <brauner@kernel.org> 2025-11-14T12:15:56+00:00 NeilBrown neil@brown.name 2025-11-13T00:18:29+00:00 urn:sha1:c9ba789dad15ba65662bba17595c0aeaa0cfcf1c xfs, fuse, ipc/mqueue need variants of start_creating or start_removing which do not check permissions. This patch adds _noperm versions of these functions. Note that do_mq_open() was only calling mntget() so it could call path_put() - it didn't really need an extra reference on the mnt. Now it doesn't call mntget() and uses end_creating() which does the dput() half of path_put(). Also mq_unlink() previously passed d_inode(dentry->d_parent) as the dir inode to vfs_unlink(). This is after locking d_inode(mnt->mnt_root) These two inodes are the same, but normally calls use the textual parent. So I've changes the vfs_unlink() call to be given d_inode(mnt->mnt_root). Reviewed-by: Amir Goldstein <amir73il@gmail.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: NeilBrown <neil@brown.name> -- changes since v2: - dir arg passed to vfs_unlink() in mq_unlink() changed to match the dir passed to lookup_noperm() - restore assignment to path->mnt even though the mntget() is removed. Link: https://patch.msgid.link/20251113002050.676694-7-neilb@ownmail.net Tested-by: syzbot@syzkaller.appspotmail.com Signed-off-by: Christian Brauner <brauner@kernel.org>