On Fri, Mar 19, 2021 at 02:38:25PM +1100, NeilBrown 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
> - check all unconfirmed clients each time any event is processed,
> - if there are unconfirmed clients, we request a wakeup after a
> exponentially decreasing time, and check again
increasing not decreasing, I think.
Is there any better way to let userland know when the contents of a
virtual file have changed?
Looks at inofity man page.... There's an "IN_MODIFY" event. I think we
could add an fsnotify_inode(inode, FS_MODIFY); at the end of
move_to_confirmed(). (I'm not sure what's the best way to get the inode
of the info file there.)
Would that help?
--b.
> This requires updating the two event loops to allow a timeout to be
> specified.
>
> When there is no other activity, but there are unconfirmed clients,
> timeout for repeat checks are after 1, 2, 4 ... 512 seconds.
> If any wait is interrupted, the next wait time is still chosen, so we
> might advance quickly through the list. But if there is lots of
> activity, we don't really need the timeout.
>
> Signed-off-by: NeilBrown <neilb@xxxxxxx>
> ---
> support/export/cache.c | 7 ++-
> support/export/export.h | 2 +-
> support/export/v4clients.c | 92 ++++++++++++++++++++++++++++++--------
> utils/mountd/svc_run.c | 7 ++-
> 4 files changed, 85 insertions(+), 23 deletions(-)
>
> diff --git a/support/export/cache.c b/support/export/cache.c
> index 3e4f53c0a32e..687b3aef27a1 100644
> --- a/support/export/cache.c
> +++ b/support/export/cache.c
> @@ -1524,6 +1524,7 @@ void cache_process_loop(void)
> {
> fd_set readfds;
> int selret;
> + struct timeval tv = { 60*60, 0 };
>
> FD_ZERO(&readfds);
>
> @@ -1533,8 +1534,10 @@ void cache_process_loop(void)
> v4clients_set_fds(&readfds);
>
> selret = select(FD_SETSIZE, &readfds,
> - (void *) 0, (void *) 0, (struct timeval *) 0);
> + (void *) 0, (void *) 0, &tv);
>
> + tv.tv_sec = 60*60;
> + tv.tv_usec = 0;
>
> switch (selret) {
> case -1:
> @@ -1546,7 +1549,7 @@ void cache_process_loop(void)
>
> default:
> cache_process_req(&readfds);
> - v4clients_process(&readfds);
> + v4clients_process(&readfds, &tv);
> }
> }
> }
> diff --git a/support/export/export.h b/support/export/export.h
> index 8d5a0d3004ef..71d3ed39bd28 100644
> --- a/support/export/export.h
> +++ b/support/export/export.h
> @@ -24,7 +24,7 @@ void cache_process_loop(void);
>
> void v4clients_init(void);
> void v4clients_set_fds(fd_set *fdset);
> -int v4clients_process(fd_set *fdset);
> +int v4clients_process(fd_set *fdset, struct timeval *tv);
>
> struct nfs_fh_len *
> cache_get_filehandle(nfs_export *exp, int len, char *p);
> diff --git a/support/export/v4clients.c b/support/export/v4clients.c
> index 056ddc9b065d..04cec3136876 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;
> +static time_t unconfirmed_wait = 1;
>
> struct ent {
> unsigned long num;
> char *clientid;
> char *addr;
> int vers;
> + int unconfirmed;
> };
>
> static int ent_cmp(const void *av, const void *bv)
> @@ -89,15 +92,13 @@ 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;
> 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");
> @@ -105,32 +106,56 @@ static void add_id(int id)
> free(path);
> return;
> }
> - key = calloc(1, sizeof(*key));
> - if (!key) {
> - fclose(f);
> - free(path);
> - return;
> - }
> - key->num = id;
> 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 (!key->unconfirmed)
> + xlog(L_NOTICE, "v4.%d client attached: %s from %s",
> + key->vers, key->clientid ?: "-none-",
> + key->addr ?: "-none-");
> +}
> +
> +static void add_id(int id)
> +{
> + struct ent **ent;
> + struct ent *key;
> +
> + key = calloc(1, sizeof(*key));
> + if (!key) {
> + return;
> + }
> + key->num = id;
>
> ent = tsearch(key, &tree_root, ent_cmp);
>
> if (!ent || *ent != key)
> /* Already existed, or insertion failed */
> free_ent(key);
> + else {
> + read_info(key);
> + if (key->unconfirmed)
> + unconfirmed_wait = 1;
> + }
> }
>
> static void del_id(int id)
> @@ -143,18 +168,43 @@ 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);
> free_ent(ent);
> }
>
> -int v4clients_process(fd_set *fdset)
> +static void check_one(const void *ventp, VISIT which, int depth)
> +{
> + struct ent * const *ep = ventp;
> + struct ent *ent;
> +
> + if (depth >= 0 && /* Silence "unused paramter" warning */
> + which != preorder && which != leaf)
> + return;
> +
> + ent = *ep;
> + if (ent->unconfirmed)
> + read_info(ent);
> +}
> +
> +static void check_unconfirmed(void)
> +{
> + if (!have_unconfirmed)
> + return;
> + have_unconfirmed = 0;
> + twalk(tree_root, check_one);
> +}
> +
> +int v4clients_process(fd_set *fdset, struct timeval *tv)
> {
> char buf[4096] __attribute__((aligned(__alignof__(struct inotify_event))));
> const struct inotify_event *ev;
> ssize_t len;
> char *ptr;
>
> + check_unconfirmed();
> +
> if (clients_fd < 0 ||
> !FD_ISSET(clients_fd, fdset))
> return 0;
> @@ -174,6 +224,12 @@ int v4clients_process(fd_set *fdset)
> del_id(id);
> }
> }
> + if (have_unconfirmed && tv->tv_sec > unconfirmed_wait) {
> + tv->tv_sec = unconfirmed_wait;
> + tv->tv_usec = 0;
> + if (unconfirmed_wait < 300)
> + unconfirmed_wait <<= 1;
> + }
> return 1;
> }
>
> diff --git a/utils/mountd/svc_run.c b/utils/mountd/svc_run.c
> index 167b9757bde2..042bed8957b9 100644
> --- a/utils/mountd/svc_run.c
> +++ b/utils/mountd/svc_run.c
> @@ -95,6 +95,7 @@ my_svc_run(void)
> {
> fd_set readfds;
> int selret;
> + struct timeval tv = { 60*60, 0 };
>
> for (;;) {
>
> @@ -103,8 +104,10 @@ my_svc_run(void)
> v4clients_set_fds(&readfds);
>
> selret = select(FD_SETSIZE, &readfds,
> - (void *) 0, (void *) 0, (struct timeval *) 0);
> + (void *) 0, (void *) 0, &tv);
>
> + tv.tv_sec = 60*60;
> + tv.tv_usec = 0;
>
> switch (selret) {
> case -1:
> @@ -116,7 +119,7 @@ my_svc_run(void)
>
> default:
> selret -= cache_process_req(&readfds);
> - selret -= v4clients_process(&readfds);
> + selret -= v4clients_process(&readfds, &tv);
> if (selret)
> svc_getreqset(&readfds);
> }
> --
> 2.30.1
>
