Date: Sat, 23 Aug 2014 11:38:32 +0000 (UTC) From: Edward Tomasz Napierala <trasz@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r270399 - head/sys/fs/autofs Message-ID: <201408231138.s7NBcWwa060935@svn.freebsd.org>
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Author: trasz Date: Sat Aug 23 11:38:31 2014 New Revision: 270399 URL: http://svnweb.freebsd.org/changeset/base/270399 Log: Add comment explaining one of the quirks in autofs. MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Modified: head/sys/fs/autofs/autofs.c Modified: head/sys/fs/autofs/autofs.c ============================================================================== --- head/sys/fs/autofs/autofs.c Sat Aug 23 11:34:56 2014 (r270398) +++ head/sys/fs/autofs/autofs.c Sat Aug 23 11:38:31 2014 (r270399) @@ -595,6 +595,14 @@ autofs_open(struct cdev *dev, int flags, { sx_xlock(&sc->sc_lock); + /* + * We must never block automountd(8) and its descendants, and we use + * session ID to determine that: we store session id of the process + * that opened the device, and then compare it with session ids + * of triggering processes. This means running a second automountd(8) + * instance would break the previous one. The check below prevents + * it from happening. + */ if (sc->sc_dev_opened) { sx_xunlock(&sc->sc_lock); return (EBUSY);
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