[PATCH V3] idmapd: Use inotify instead of dnotify

[Alan Swanson <reiver@improbability.net>]

Remove last use of dnotify in nfs-utils by bringing idmapd upto
date with (required) inotify use by gssd and blkmapd.
---
 utils/idmapd/idmapd.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

Got annoyed by the dnotify kernel requirement. Read the last
discussion "DNOTIFY to INOTIFY migration" posted in 2014 and while
still not officially depreciated, dnotify was officially "replaced"
by inotify in Linux 2.6.13 in 2005. Would be nice to sync this
requirement across the codebase.

V2: Init wd to -1 not 0
V3: Remove EV_PERSIST

Have been using V3 patch in production for the last year since a
few days after last V2 email.

diff --git a/utils/idmapd/idmapd.c b/utils/idmapd/idmapd.c
index 4811e0f..2dd9c31 100644
--- a/utils/idmapd/idmapd.c
+++ b/utils/idmapd/idmapd.c
@@ -36,7 +36,7 @@
 
 #include <sys/types.h>
 #include <sys/time.h>
-#include <sys/poll.h>
+#include <sys/inotify.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <time.h>
@@ -205,15 +205,16 @@ static void usage(char *progname)
 int
 main(int argc, char **argv)
 {
-	int fd = 0, opt, fg = 0, nfsdret = -1;
+	int wd = -1, opt, fg = 0, nfsdret = -1;
 	struct idmap_clientq icq;
-	struct event rootdirev, clntdirev, svrdirev;
+	struct event rootdirev, clntdirev, svrdirev, inotifyev;
 	struct event initialize;
 	struct passwd *pw;
 	struct group *gr;
 	struct stat sb;
 	char *xpipefsdir = NULL;
 	int serverstart = 1, clientstart = 1;
+	int inotify_fd;
 	int ret;
 	char *progname;
 	char *conf_path = NULL;
@@ -373,18 +374,15 @@ main(int argc, char **argv)
 			}
 		}
 
-		if ((fd = open(pipefsdir, O_RDONLY)) == -1)
-			xlog_err("main: open(%s): %s", pipefsdir, strerror(errno));
-
-		if (fcntl(fd, F_SETSIG, SIGUSR1) == -1)
-			xlog_err("main: fcntl(%s): %s", pipefsdir, strerror(errno));
-
-		if (fcntl(fd, F_NOTIFY,
-			DN_CREATE | DN_DELETE | DN_MODIFY | DN_MULTISHOT) == -1) {
-			xlog_err("main: fcntl(%s): %s", pipefsdir, strerror(errno));
-			if (errno == EINVAL)
-				xlog_err("main: Possibly no Dnotify support in kernel.");
+		inotify_fd = inotify_init1(IN_NONBLOCK);
+		if (inotify_fd == -1) {
+			xlog_err("Unable to initialise inotify_init1: %s\n", strerror(errno));
+		} else {
+			wd = inotify_add_watch(inotify_fd, pipefsdir, IN_CREATE | IN_DELETE | IN_MODIFY);
+			if (wd < 0)
+				xlog_err("Unable to inotify_add_watch(%s): %s\n", pipefsdir, strerror(errno));
 		}
+
 		TAILQ_INIT(&icq);
 
 		/* These events are persistent */
@@ -394,6 +392,10 @@ main(int argc, char **argv)
 		signal_add(&clntdirev, NULL);
 		signal_set(&svrdirev, SIGHUP, svrreopen, NULL);
 		signal_add(&svrdirev, NULL);
+		if ( wd >= 0) {
+			event_set(&inotifyev, inotify_fd, EV_READ, dirscancb, &icq);
+			event_add(&inotifyev, NULL);
+		}
 
 		/* Fetch current state */
 		/* (Delay till start of event_dispatch to avoid possibly losing
@@ -402,7 +404,7 @@ main(int argc, char **argv)
 		evtimer_add(&initialize, &now);
 	}
 
-	if (nfsdret != 0 && fd == 0)
+	if (nfsdret != 0 && wd < 0)
 		xlog_err("main: Neither NFS client nor NFSd found");
 
 	daemon_ready();
-- 
2.16.4