autofs - dont hold spin lock over direct mount expire (1c4344a5) · Commits · 戴 / test

Commit altered the autofs indirect mount expire to not hold a spin lock during the expire check. The direct mount expire needs the same treatment because to make autofs expires namespace aware may_umount_tree() needs to to use a similar method to may_umount() when checking if a mount tree is in use. This means may_umount_tree() will end up taking the namespace_sem for the check so the autofs direct mount expire won't be allowed to hold a spin lock over the check. Signed-off-by:

Ian Kent <raven@themaw.net> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Omar Sandoval <osandov@osandov.com> Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

fs/autofs4/expire.c

+10 −7

Original line number	Diff line number	Diff line
		@@ -310,26 +310,29 @@ struct dentry autofs4_expire_direct(struct super_block sb,
		now = jiffies;
		timeout = sbi->exp_timeout;

		if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
		spin_lock(&sbi->fs_lock);
		ino = autofs4_dentry_ino(root);
		/* No point expiring a pending mount */
		if (ino->flags & AUTOFS_INF_PENDING)
		if (ino->flags & AUTOFS_INF_PENDING) {
		spin_unlock(&sbi->fs_lock);
		goto out;
		if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
		}
		ino->flags \|= AUTOFS_INF_WANT_EXPIRE;
		spin_unlock(&sbi->fs_lock);
		synchronize_rcu();
		spin_lock(&sbi->fs_lock);
		if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
		spin_lock(&sbi->fs_lock);
		ino->flags \|= AUTOFS_INF_EXPIRING;
		init_completion(&ino->expire_complete);
		spin_unlock(&sbi->fs_lock);
		return root;
		}
		spin_lock(&sbi->fs_lock);
		ino->flags &= ~AUTOFS_INF_WANT_EXPIRE;
		spin_unlock(&sbi->fs_lock);
		}
		out:
		spin_unlock(&sbi->fs_lock);
		dput(root);

		return NULL;

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