Commit 062d26ad authored Aug 23, 2022 by Linus Torvalds

idmapping

Pull file_remove_privs() fix from Christian Brauner:
 "As part of Stefan's and Jens' work to add async buffered write
  support to xfs we refactored file_remove_privs() and added
  __file_remove_privs() to avoid calling __remove_privs() when
  IOCB_NOWAIT is passed.

  While debugging a recent performance regression report I found that
  during review we missed that commit faf99b56 ("fs: add
  __remove_file_privs() with flags parameter") accidently changed
  behavior when dentry_needs_remove_privs() returns zero.

  Before the commit it would still call inode_has_no_xattr() setting
  the S_NOSEC bit and thereby avoiding even calling into
  dentry_needs_remove_privs() the next time this function is called.
  After that commit inode_has_no_xattr() would only be called if
  __remove_privs() had to be called.

  Restore the old behavior. This is likely the cause of the performance
  regression"

* tag 'fs.fixes.v6.0-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping:
  fs: __file_remove_privs(): restore call to inode_has_no_xattr()

parents df0219d1 41191cf6

fs/inode.c

+8 −6

Original line number	Diff line number	Diff line
		@@ -2018,23 +2018,25 @@ static int __file_remove_privs(struct file *file, unsigned int flags)
		{
		struct dentry *dentry = file_dentry(file);
		struct inode *inode = file_inode(file);
		int error;
		int error = 0;
		int kill;

		if (IS_NOSEC(inode) \|\| !S_ISREG(inode->i_mode))
		return 0;

		kill = dentry_needs_remove_privs(dentry);
		if (kill <= 0)
		if (kill < 0)
		return kill;

		if (kill) {
		if (flags & IOCB_NOWAIT)
		return -EAGAIN;

		error = __remove_privs(file_mnt_user_ns(file), dentry, kill);
		}

		if (!error)
		inode_has_no_xattr(inode);

		return error;
		}