Merge tag 'vfs-6.19-rc1.directory.locking' of 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()

1 files changed, 26 insertions, 88 deletions

diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index 3747851b61c8..03fd7409be79 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -49,27 +49,9 @@ static void ksmbd_vfs_inherit_owner(struct ksmbd_work *work,
 	i_uid_write(inode, i_uid_read(parent_inode));
 }
 
-/**
- * ksmbd_vfs_lock_parent() - lock parent dentry if it is stable
- * @parent: parent dentry
- * @child: child dentry
- *
- * Returns: %0 on success, %-ENOENT if the parent dentry is not stable
- */
-int ksmbd_vfs_lock_parent(struct dentry *parent, struct dentry *child)
-{
-	inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
-	if (child->d_parent != parent) {
-		inode_unlock(d_inode(parent));
-		return -ENOENT;
-	}
-
-	return 0;
-}
-
 static int ksmbd_vfs_path_lookup(struct ksmbd_share_config *share_conf,
 				 char *pathname, unsigned int flags,
-				 struct path *path, bool do_lock)
+				 struct path *path, bool for_remove)
 {
 	struct qstr last;
 	struct filename *filename __free(putname) = NULL;
@@ -99,22 +81,20 @@ static int ksmbd_vfs_path_lookup(struct ksmbd_share_config *share_conf,
 		return -ENOENT;
 	}
 
-	if (do_lock) {
+	if (for_remove) {
 		err = mnt_want_write(path->mnt);
 		if (err) {
 			path_put(path);
 			return -ENOENT;
 		}
 
-		inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
-		d = lookup_one_qstr_excl(&last, path->dentry, 0);
+		d = start_removing_noperm(path->dentry, &last);
 
 		if (!IS_ERR(d)) {
 			dput(path->dentry);
 			path->dentry = d;
 			return 0;
 		}
-		inode_unlock(path->dentry->d_inode);
 		mnt_drop_write(path->mnt);
 		path_put(path);
 		return -ENOENT;
@@ -680,7 +660,6 @@ out1:
 int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path,
 		     char *newname, int flags)
 {
-	struct dentry *old_parent, *new_dentry, *trap;
 	struct dentry *old_child = old_path->dentry;
 	struct path new_path;
 	struct qstr new_last;
@@ -690,7 +669,6 @@ int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path,
 	struct ksmbd_file *parent_fp;
 	int new_type;
 	int err, lookup_flags = LOOKUP_NO_SYMLINKS;
-	int target_lookup_flags = LOOKUP_RENAME_TARGET | LOOKUP_CREATE;
 
 	if (ksmbd_override_fsids(work))
 		return -ENOMEM;
@@ -701,14 +679,6 @@ int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path,
 		goto revert_fsids;
 	}
 
-	/*
-	 * explicitly handle file overwrite case, for compatibility with
-	 * filesystems that may not support rename flags (e.g: fuse)
-	 */
-	if (flags & RENAME_NOREPLACE)
-		target_lookup_flags |= LOOKUP_EXCL;
-	flags &= ~(RENAME_NOREPLACE);
-
 retry:
 	err = vfs_path_parent_lookup(to, lookup_flags | LOOKUP_BENEATH,
 				     &new_path, &new_last, &new_type,
@@ -725,17 +695,14 @@ retry:
 	if (err)
 		goto out2;
 
-	trap = lock_rename_child(old_child, new_path.dentry);
-	if (IS_ERR(trap)) {
-		err = PTR_ERR(trap);
+	rd.mnt_idmap		= mnt_idmap(old_path->mnt);
+	rd.old_parent		= NULL;
+	rd.new_parent		= new_path.dentry;
+	rd.flags		= flags;
+	rd.delegated_inode	= NULL,
+	err = start_renaming_dentry(&rd, lookup_flags, old_child, &new_last);
+	if (err)
 		goto out_drop_write;
-	}
-
-	old_parent = dget(old_child->d_parent);
-	if (d_unhashed(old_child)) {
-		err = -EINVAL;
-		goto out3;
-	}
 
 	parent_fp = ksmbd_lookup_fd_inode(old_child->d_parent);
 	if (parent_fp) {
@@ -748,44 +715,17 @@ retry:
 		ksmbd_fd_put(work, parent_fp);
 	}
 
-	new_dentry = lookup_one_qstr_excl(&new_last, new_path.dentry,
-					  lookup_flags | target_lookup_flags);
-	if (IS_ERR(new_dentry)) {
-		err = PTR_ERR(new_dentry);
-		goto out3;
-	}
-
-	if (d_is_symlink(new_dentry)) {
+	if (d_is_symlink(rd.new_dentry)) {
 		err = -EACCES;
-		goto out4;
-	}
-
-	if (old_child == trap) {
-		err = -EINVAL;
-		goto out4;
-	}
-
-	if (new_dentry == trap) {
-		err = -ENOTEMPTY;
-		goto out4;
+		goto out3;
 	}
 
-	rd.mnt_idmap		= mnt_idmap(old_path->mnt),
-	rd.old_parent		= old_parent,
-	rd.old_dentry		= old_child,
-	rd.new_parent		= new_path.dentry,
-	rd.new_dentry		= new_dentry,
-	rd.flags		= flags,
-	rd.delegated_inode	= NULL,
 	err = vfs_rename(&rd);
 	if (err)
 		ksmbd_debug(VFS, "vfs_rename failed err %d\n", err);
 
-out4:
-	dput(new_dentry);
 out3:
-	dput(old_parent);
-	unlock_rename(old_parent, new_path.dentry);
+	end_renaming(&rd);
 out_drop_write:
 	mnt_drop_write(old_path->mnt);
 out2:
@@ -1083,18 +1023,17 @@ int ksmbd_vfs_unlink(struct file *filp)
 		return err;
 
 	dir = dget_parent(dentry);
-	err = ksmbd_vfs_lock_parent(dir, dentry);
-	if (err)
+	dentry = start_removing_dentry(dir, dentry);
+	err = PTR_ERR(dentry);
+	if (IS_ERR(dentry))
 		goto out;
-	dget(dentry);
 
 	if (S_ISDIR(d_inode(dentry)->i_mode))
 		err = vfs_rmdir(idmap, d_inode(dir), dentry, NULL);
 	else
 		err = vfs_unlink(idmap, d_inode(dir), dentry, NULL);
 
-	dput(dentry);
-	inode_unlock(d_inode(dir));
+	end_removing(dentry);
 	if (err)
 		ksmbd_debug(VFS, "failed to delete, err %d\n", err);
 out:
@@ -1206,7 +1145,7 @@ static int ksmbd_vfs_lookup_in_dir(const struct path *dir, char *name,
 static
 int __ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath,
 			  unsigned int flags,
-			  struct path *path, bool caseless, bool do_lock)
+			  struct path *path, bool caseless, bool for_remove)
 {
 	struct ksmbd_share_config *share_conf = work->tcon->share_conf;
 	struct path parent_path;
@@ -1214,7 +1153,7 @@ int __ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath,
 	int err;
 
 retry:
-	err = ksmbd_vfs_path_lookup(share_conf, filepath, flags, path, do_lock);
+	err = ksmbd_vfs_path_lookup(share_conf, filepath, flags, path, for_remove);
 	if (!err || !caseless)
 		return err;
 
@@ -1285,7 +1224,7 @@ int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath,
 }
 
 /**
- * ksmbd_vfs_kern_path_locked() - lookup a file and get path info
+ * ksmbd_vfs_kern_path_start_remove() - lookup a file and get path info prior to removal
  * @work:		work
  * @filepath:		file path that is relative to share
  * @flags:		lookup flags
@@ -1297,20 +1236,19 @@ int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath,
  * filesystem will have been gained.
  * Return:	0 on if file was found, otherwise error
  */
-int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *filepath,
-			       unsigned int flags,
-			       struct path *path, bool caseless)
+int ksmbd_vfs_kern_path_start_removing(struct ksmbd_work *work, char *filepath,
+				       unsigned int flags,
+				       struct path *path, bool caseless)
 {
 	return __ksmbd_vfs_kern_path(work, filepath, flags, path,
 				     caseless, true);
 }
 
-void ksmbd_vfs_kern_path_unlock(const struct path *path)
+void ksmbd_vfs_kern_path_end_removing(const struct path *path)
 {
-	/* While lock is still held, ->d_parent is safe */
-	inode_unlock(d_inode(path->dentry->d_parent));
+	end_removing(path->dentry);
 	mnt_drop_write(path->mnt);
-	path_put(path);
+	mntput(path->mnt);
 }
 
 struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work,