[PATCH v2] mountd/exportd: only log confirmed clients, and poll for updates

[NeilBrown <neilb@suse.de>]

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It is possible (and common with the Linux NFS client) for the nfs server
to receive multiple SET_CLIENT_ID or EXCHANGE_ID requests when starting
a connection.  This results in some clients appearing in
 /proc/fs/nfsd/clients
which never get confirmed.  mountd currently logs these, but they aren't
really helpful.

If the kernel supports the reporting of the confirmation status of
clients, we can suppress the message until a client is confirmed.

With this patch we:
 - record if the client is confirmed, assuming it is if the status is
    not reported
 - don't log unconfirmed clients
 - request MODIFY notification from unconfirmed clients.
 - recheck an info file when it is modified.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 support/export/v4clients.c | 86 +++++++++++++++++++++++++++++---------
 1 file changed, 67 insertions(+), 19 deletions(-)

diff --git a/support/export/v4clients.c b/support/export/v4clients.c
index 056ddc9b065d..f2c9bb482ba7 100644
--- a/support/export/v4clients.c
+++ b/support/export/v4clients.c
@@ -48,12 +48,15 @@ void v4clients_set_fds(fd_set *fdset)
 }
 
 static void *tree_root;
+static int have_unconfirmed;
 
 struct ent {
 	unsigned long num;
 	char *clientid;
 	char *addr;
 	int vers;
+	int unconfirmed;
+	int wid;
 };
 
 static int ent_cmp(const void *av, const void *bv)
@@ -89,15 +92,14 @@ static char *dup_line(char *line)
 	return ret;
 }
 
-static void add_id(int id)
+static void read_info(struct ent *key)
 {
 	char buf[2048];
-	struct ent **ent;
-	struct ent *key;
 	char *path;
+	int was_unconfirmed = key->unconfirmed;
 	FILE *f;
 
-	if (asprintf(&path, "/proc/fs/nfsd/clients/%d/info", id) < 0)
+	if (asprintf(&path, "/proc/fs/nfsd/clients/%lu/info", key->num) < 0)
 		return;
 
 	f = fopen(path, "r");
@@ -105,35 +107,64 @@ static void add_id(int id)
 		free(path);
 		return;
 	}
-	key = calloc(1, sizeof(*key));
-	if (!key) {
-		fclose(f);
-		free(path);
-		return;
-	}
-	key->num = id;
+	if (key->wid < 0)
+		key->wid = inotify_add_watch(clients_fd, path, IN_MODIFY);
+
 	while (fgets(buf, sizeof(buf), f)) {
-		if (strncmp(buf, "clientid: ", 10) == 0)
+		if (strncmp(buf, "clientid: ", 10) == 0) {
+			free(key->clientid);
 			key->clientid = dup_line(buf+10);
-		if (strncmp(buf, "address: ", 9) == 0)
+		}
+		if (strncmp(buf, "address: ", 9) == 0) {
+			free(key->addr);
 			key->addr = dup_line(buf+9);
+		}
 		if (strncmp(buf, "minor version: ", 15) == 0)
 			key->vers = atoi(buf+15);
+		if (strncmp(buf, "status: ", 8) == 0 &&
+		    strstr(buf, " unconfirmed") != NULL) {
+			key->unconfirmed = 1;
+			have_unconfirmed = 1;
+		}
+		if (strncmp(buf, "status: ", 8) == 0 &&
+		    strstr(buf, " confirmed") != NULL)
+			key->unconfirmed = 0;
 	}
 	fclose(f);
 	free(path);
 
-	xlog(L_NOTICE, "v4.%d client attached: %s from %s",
-	     key->vers, key->clientid, key->addr);
+	if (was_unconfirmed && !key->unconfirmed)
+		xlog(L_NOTICE, "v4.%d client attached: %s from %s",
+		     key->vers, key->clientid ?: "-none-",
+		     key->addr ?: "-none-");
+	if (!key->unconfirmed && ent->wid >= 0) {
+		inotify_rm_watch(clients_fd, ent->wid);
+		ent->wid = -1;
+	}
+}
+
+static void add_id(int id)
+{
+	struct ent **ent;
+	struct ent *key;
+
+	key = calloc(1, sizeof(*key));
+	if (!key) {
+		return;
+	}
+	key->num = id;
+	key->wid = -1;
 
 	ent = tsearch(key, &tree_root, ent_cmp);
 
 	if (!ent || *ent != key)
 		/* Already existed, or insertion failed */
 		free_ent(key);
+	else
+		read_info(key);
 }
 
-static void del_id(int id)
+static void del_id(unsigned long id)
 {
 	struct ent key = {.num = id};
 	struct ent **e, *ent;
@@ -143,11 +174,27 @@ static void del_id(int id)
 		return;
 	ent = *e;
 	tdelete(ent, &tree_root, ent_cmp);
-	xlog(L_NOTICE, "v4.%d client detached: %s from %s",
-	     ent->vers, ent->clientid, ent->addr);
+	if (!ent->unconfirmed)
+		xlog(L_NOTICE, "v4.%d client detached: %s from %s",
+		     ent->vers, ent->clientid, ent->addr);
+	if (ent->wid >= 0)
+		inotify_rm_watch(clients_fd, ent->wid);
 	free_ent(ent);
 }
 
+static void check_id(unsigned long id)
+{
+	struct ent key = {.num = id};
+	struct ent **e, *ent;
+
+	e = tfind(&key, &tree_root, ent_cmp);
+	if (!e || !*e)
+		return;
+	ent = *e;
+	if (ent->unconfirmed)
+		read_info(ent);
+}
+
 int v4clients_process(fd_set *fdset)
 {
 	char buf[4096] __attribute__((aligned(__alignof__(struct inotify_event))));
@@ -172,8 +219,9 @@ int v4clients_process(fd_set *fdset)
 				add_id(id);
 			if (ev->mask & IN_DELETE)
 				del_id(id);
+			if (ev->mask & IN_MODIFY)
+				check_id(id);
 		}
 	}
 	return 1;
 }
-
-- 
2.30.1


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