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

[Chuck Lever III <chuck.lever@oracle.com>]

> On Mar 19, 2021, at 6:39 PM, NeilBrown <neilb@suse.de> wrote:
> 
> 
> 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>

Hello Neil!

I've committed v2 of this patch to the for-next topic branch at

git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git


> ---
> 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
> 

--
Chuck Lever