On Mon, 2025-12-08 at 16:12 -0500, Benjamin Marzinski wrote:
> When libmpathpersist notifies multipathd that a key has been
> registered,
> cli_setprstatus() calls pr_register_active_paths() with a flag to let
> it
> know that the paths are likely already registered, and it can skip
> re-registering them, as long as the number of active paths matches
> the
> number of registered keys. This shortcut can fail, causing multipathd
> to
> not register needed paths, if either a path becomes usable and
> another
> becomes unusable while libmpathpersist is running or if there already
> were registered keys for I_T Nexus's that don't correspond to path
> devices.
>
> To make this shortcut work in cases like that, this commit adds a new
> multipathd command "setprstatus map <map> pathlist <pathlist>", where
> <pathlist> is a quoted, comma separated list of scsi path devices.
> libmpathpersist will send out the list of paths it registered the key
> on. pr_register_active_paths() will skip calling
> mpath_pr_event_handle()
> for paths on that list.
>
> In order to deal with the possiblity of a preempt occuring while
> libmpathpersist was running, the code still needs to check that it
> has
> the expected number of keys.
>
> Fixes: f7d6cd17 ("multipathd: Fix race while registering PR key")
> Signed-off-by: Benjamin Marzinski <[email protected]>
Minor comments below.
Regards,
Martin
> ---
>
> Was patch 4/4 of "multipath-tools: Yet Another PR fix"
> Changes in v2 (assuming we agree to use this patch at all):
> added a semi-colon after the "skip" label to make clang happy.
>
> libmpathpersist/mpath_persist_int.c | 6 +--
> libmpathpersist/mpath_updatepr.c | 48 +++++++++++++++++-----
> libmpathpersist/mpathpr.h | 4 +-
> multipathd/callbacks.c | 1 +
> multipathd/cli.c | 1 +
> multipathd/cli.h | 2 +
> multipathd/cli_handlers.c | 39 ++++++++++++++++--
> multipathd/main.c | 62 +++++++++++++++++++--------
> --
> multipathd/main.h | 3 +-
> multipathd/multipathd.8.in | 6 +++
> 10 files changed, 133 insertions(+), 39 deletions(-)
>
> diff --git a/libmpathpersist/mpath_persist_int.c
> b/libmpathpersist/mpath_persist_int.c
> index 91c53419..14f7ba83 100644
> --- a/libmpathpersist/mpath_persist_int.c
> +++ b/libmpathpersist/mpath_persist_int.c
> @@ -1001,12 +1001,12 @@ int do_mpath_persistent_reserve_out(vector
> curmp, vector pathvec, int fd,
> case MPATH_PROUT_REG_SA:
> case MPATH_PROUT_REG_IGN_SA:
> if (unregistering)
> - update_prflag(mpp->alias, 0);
> + update_prflag(mpp, 0);
> else
> - update_prflag(mpp->alias, 1);
> + update_prflag(mpp, 1);
> break;
> case MPATH_PROUT_CLEAR_SA:
> - update_prflag(mpp->alias, 0);
> + update_prflag(mpp, 0);
> if (mpp->prkey_source == PRKEY_SOURCE_FILE)
> update_prkey(mpp->alias, 0);
> break;
> diff --git a/libmpathpersist/mpath_updatepr.c
> b/libmpathpersist/mpath_updatepr.c
> index bd8ed2be..bc9c79e2 100644
> --- a/libmpathpersist/mpath_updatepr.c
> +++ b/libmpathpersist/mpath_updatepr.c
> @@ -20,8 +20,9 @@
> #include "uxsock.h"
> #include "mpathpr.h"
> #include "structs.h"
> +#include "strbuf.h"
>
> -static char *do_pr(char *alias, char *str)
> +static char *do_pr(char *alias, const char *str)
> {
> int fd;
> char *reply;
> @@ -51,24 +52,27 @@ static char *do_pr(char *alias, char *str)
> return reply;
> }
>
> -static int do_update_pr(char *alias, char *cmd, char *key)
> +static int do_update_pr(char *alias, char *cmd, const char *data)
> {
> - char str[256];
> + STRBUF_ON_STACK(buf);
> char *reply = NULL;
> int ret = -1;
>
> - if (key)
> - snprintf(str, sizeof(str), "%s map %s key %s", cmd,
> alias, key);
> + if (data)
> + print_strbuf(&buf, "%s map %s %s %s", cmd, alias,
> + strcmp(cmd, "setprkey") ? "pathlist" :
> "key",
> + data);
> else
> - snprintf(str, sizeof(str), "%s map %s", cmd, alias);
> + print_strbuf(&buf, "%s map %s", cmd, alias);
>
> - reply = do_pr(alias, str);
> + reply = do_pr(alias, get_strbuf_str(&buf));
> if (reply) {
> if (strncmp(reply, "ok", 2) == 0)
> ret = 0;
> else
> ret = -1;
> - condlog(ret ? 0 : 4, "%s: message=%s reply=%s",
> alias, str, reply);
> + condlog(ret ? 0 : 4, "%s: message=%s reply=%s",
> alias,
> + get_strbuf_str(&buf), reply);
> }
>
> free(reply);
> @@ -106,9 +110,31 @@ int get_prhold(char *mapname)
> return do_get_pr(mapname, "getprhold");
> }
>
> -int update_prflag(char *mapname, int set) {
> - return do_update_pr(mapname, (set)? "setprstatus" :
> "unsetprstatus",
> - NULL);
> +int update_prflag(struct multipath *mpp, int set)
> +{
> + STRBUF_ON_STACK(buf);
> + int i, j;
> + bool first = true;
> + struct pathgroup *pgp = NULL;
> + struct path *pp = NULL;
> +
> + if (!set)
> + return do_update_pr(mpp->alias, "unsetprstatus",
> NULL);
> +
> + append_strbuf_str(&buf, "\"");
> + vector_foreach_slot (mpp->pg, pgp, j) {
> + vector_foreach_slot (pgp->paths, pp, i) {
> + if (pp->state == PATH_UP || pp->state ==
> PATH_GHOST) {
> + if (first) {
> + append_strbuf_str(&buf, pp-
> >dev);
> + first = false;
> + } else
> + print_strbuf(&buf, " %s",
> pp->dev);
Nitpick: in the commit description you said the list was comma-
separated, here it looks like space-separated.
Also, I'd prefer to use pp->dev_t here unless there are good reasons
against that.
> + }
> + }
> + }
> + append_strbuf_str(&buf, "\"");
> + return do_update_pr(mpp->alias, "setprstatus",
> get_strbuf_str(&buf));
> }
>
> int update_prhold(char *mapname, bool set)
> diff --git a/libmpathpersist/mpathpr.h b/libmpathpersist/mpathpr.h
> index 99d6b82f..adbfc865 100644
> --- a/libmpathpersist/mpathpr.h
> +++ b/libmpathpersist/mpathpr.h
> @@ -1,12 +1,14 @@
> #ifndef MPATHPR_H_INCLUDED
> #define MPATHPR_H_INCLUDED
>
> +#include "structs.h"
> +
> /*
> * This header file contains symbols that are only used by
> * libmpathpersist internally.
> */
>
> -int update_prflag(char *mapname, int set);
> +int update_prflag(struct multipath *mpp, int set);
> int update_prkey_flags(char *mapname, uint64_t prkey, uint8_t
> sa_flags);
> int get_prflag(char *mapname);
> int get_prhold(char *mapname);
> diff --git a/multipathd/callbacks.c b/multipathd/callbacks.c
> index b6b57f45..1129855b 100644
> --- a/multipathd/callbacks.c
> +++ b/multipathd/callbacks.c
> @@ -59,6 +59,7 @@ void init_handler_callbacks(void)
> set_unlocked_handler_callback(VRB_SHUTDOWN,
> HANDLER(cli_shutdown));
> set_handler_callback(VRB_GETPRSTATUS | Q1_MAP,
> HANDLER(cli_getprstatus));
> set_handler_callback(VRB_SETPRSTATUS | Q1_MAP,
> HANDLER(cli_setprstatus));
> + set_handler_callback(VRB_SETPRSTATUS | Q1_MAP | Q2_PATHLIST,
> HANDLER(cli_setprstatus_list));
> set_handler_callback(VRB_UNSETPRSTATUS | Q1_MAP,
> HANDLER(cli_unsetprstatus));
> set_handler_callback(VRB_FORCEQ | Q1_DAEMON,
> HANDLER(cli_force_no_daemon_q));
> set_handler_callback(VRB_RESTOREQ | Q1_DAEMON,
> HANDLER(cli_restore_no_daemon_q));
> diff --git a/multipathd/cli.c b/multipathd/cli.c
> index d0e6cebc..0d679c86 100644
> --- a/multipathd/cli.c
> +++ b/multipathd/cli.c
> @@ -227,6 +227,7 @@ load_keys (void)
> r += add_key(keys, "getprhold", VRB_GETPRHOLD, 0);
> r += add_key(keys, "setprhold", VRB_SETPRHOLD, 0);
> r += add_key(keys, "unsetprhold", VRB_UNSETPRHOLD, 0);
> + r += add_key(keys, "pathlist", KEY_PATHLIST, 1);
>
> if (r) {
> free_keys(keys);
> diff --git a/multipathd/cli.h b/multipathd/cli.h
> index 5a943a45..3e607389 100644
> --- a/multipathd/cli.h
> +++ b/multipathd/cli.h
> @@ -62,6 +62,7 @@ enum {
> KEY_LOCAL = 81,
> KEY_GROUP = 82,
> KEY_KEY = 83,
> + KEY_PATHLIST = 84,
> };
>
> /*
> @@ -94,6 +95,7 @@ enum {
> Q2_LOCAL = KEY_LOCAL << 16,
> Q2_GROUP = KEY_GROUP << 16,
> Q2_KEY = KEY_KEY << 16,
> + Q2_PATHLIST = KEY_PATHLIST << 16,
>
> /* byte 3: qualifier 3 */
> Q3_FMT = KEY_FMT << 24,
> diff --git a/multipathd/cli_handlers.c b/multipathd/cli_handlers.c
> index 2812d01e..5770dcec 100644
> --- a/multipathd/cli_handlers.c
> +++ b/multipathd/cli_handlers.c
> @@ -31,6 +31,7 @@
> #include "foreign.h"
> #include "strbuf.h"
> #include "cli_handlers.h"
> +#include <ctype.h>
>
> static struct path *
> find_path_by_str(const struct vector_s *pathvec, const char *str,
> @@ -1276,8 +1277,8 @@ cli_getprstatus (void * v, struct strbuf
> *reply, void * data)
> return 0;
> }
>
> -static int
> -cli_setprstatus(void * v, struct strbuf *reply, void * data)
> +static int do_setprstatus(void * v, struct strbuf *reply, void *
> data,
> + const struct vector_s *registered_paths)
> {
> struct multipath * mpp;
> struct vectors * vecs = (struct vectors *)data;
> @@ -1291,7 +1292,7 @@ cli_setprstatus(void * v, struct strbuf *reply,
> void * data)
>
> if (mpp->prflag != PR_SET) {
> set_pr(mpp);
> - pr_register_active_paths(mpp, true);
> + pr_register_active_paths(mpp, registered_paths);
> if (mpp->prflag == PR_SET)
> condlog(2, "%s: prflag set", param);
> else
> @@ -1302,6 +1303,38 @@ cli_setprstatus(void * v, struct strbuf
> *reply, void * data)
> return 0;
> }
>
> +static int
> +cli_setprstatus(void * v, struct strbuf *reply, void * data)
> +{
> + return do_setprstatus(v, reply, data, NULL);
> +}
> +
> +static int
> +cli_setprstatus_list(void * v, struct strbuf *reply, void * data)
> +{
> + int r;
> + struct vector_s registered_paths = { .allocated = 0 };
> + char *ptr = get_keyparam(v, KEY_PATHLIST);
> +
> + while (isspace(*ptr))
> + ptr++;
> + while (*ptr) {
> + if (!vector_alloc_slot(®istered_paths)) {
> + r = -ENOMEM;
> + goto out;
> + }
> + vector_set_slot(®istered_paths, ptr);
> + while (*ptr && !isspace(*ptr))
> + ptr++;
> + while (isspace(*ptr))
> + *ptr++ = '\0';
> + }
> + r = do_setprstatus(v, reply, data, ®istered_paths);
> +out:
> + vector_reset(®istered_paths);
> + return r;
> +}
> +
> static int
> cli_unsetprstatus(void * v, struct strbuf *reply, void * data)
> {
> diff --git a/multipathd/main.c b/multipathd/main.c
> index a7650639..f00444b4 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -630,28 +630,50 @@ flush_map_nopaths(struct multipath *mpp, struct
> vectors *vecs) {
> return true;
> }
>
> -void pr_register_active_paths(struct multipath *mpp, bool
> check_nr_active)
> +/*
> + * If reg_paths in non-NULL, it is a vector of paths that
> libmpathpersist
> + * registered. If the number of registered keys is smaller than the
> number
> + * of registered paths, then likely a preempt that occurred while
> + * libmpathpersist was registering the key. As long as there are
> still some
> + * registered keys, treat the preempt as happening first, and make
> sure to
> + * register keys on all the paths. If the number of registered keys
> is at
> + * least as large as the number of registered paths, then no preempt
> happened,
> + * and multipathd does not need to re-register the paths that
> libmpathpersist
> + * handled
> + */
> +void pr_register_active_paths(struct multipath *mpp,
> + const struct vector_s *reg_paths)
> {
> - unsigned int i, j, nr_keys = 0;
> - unsigned int nr_active = 0;
> + unsigned int i, j, k, nr_keys = 0;
> + unsigned int wanted_nr = VECTOR_SIZE(reg_paths);
> struct path *pp;
> struct pathgroup *pgp;
> -
> - if (check_nr_active) {
> - nr_active = count_active_paths(mpp);
> - if (!nr_active)
> - return;
> - }
> + char *pathname;
>
> vector_foreach_slot (mpp->pg, pgp, i) {
> vector_foreach_slot (pgp->paths, pp, j) {
> if (mpp->prflag == PR_UNSET)
> return;
> - if (pp->state == PATH_UP || pp->state ==
> PATH_GHOST) {
> - nr_keys = mpath_pr_event_handle(pp,
> nr_keys, nr_active);
> - if (check_nr_active && nr_keys ==
> nr_active)
> - return;
> + if (pp->state != PATH_UP && pp->state !=
> PATH_GHOST)
> + continue;
> + if (wanted_nr && nr_keys) {
> + vector_foreach_slot(reg_paths,
> pathname, k) {
> + if (strcmp(pp->dev,
> pathname) == 0 ||
> + strcmp(pp->dev_t,
> pathname) == 0) {
As this command is not likely to be sent by human users, do we need to
accept both dev and dev_t here?
> + goto skip;
> + }
> + }
> + }
> + nr_keys = mpath_pr_event_handle(pp, nr_keys,
> wanted_nr);
> + if (nr_keys && nr_keys < wanted_nr) {
> + /*
> + * Incorrect number of registered
> keys. Need
> + * to register all devices
> + */
> + wanted_nr = 0;
> }
> +skip:
> + ; /* a statement must follow a label on pre
> C23 clang */
> }
> }
> }
> @@ -739,7 +761,7 @@ fail:
>
> sync_map_state(mpp, false);
>
> - pr_register_active_paths(mpp, false);
> + pr_register_active_paths(mpp, NULL);
>
> if (VECTOR_SIZE(offline_paths) != 0)
> handle_orphaned_offline_paths(offline_paths);
> @@ -1413,7 +1435,7 @@ rescan:
>
> if (retries >= 0) {
> if ((mpp->prflag == PR_SET && prflag != PR_SET) ||
> start_waiter)
> - pr_register_active_paths(mpp, false);
> + pr_register_active_paths(mpp, NULL);
> condlog(2, "%s [%s]: path added to devmap %s",
> pp->dev, pp->dev_t, mpp->alias);
> return 0;
> @@ -2658,7 +2680,7 @@ update_path_state (struct vectors * vecs,
> struct path * pp)
> "reservation registration", pp-
> >dev);
> mpath_pr_event_handle(pp, 0, 0);
> if (pp->mpp->prflag == PR_SET && prflag !=
> PR_SET)
> - pr_register_active_paths(pp->mpp,
> false);
> + pr_register_active_paths(pp->mpp,
> NULL);
> }
>
> /*
> @@ -3319,7 +3341,7 @@ configure (struct vectors * vecs, enum
> force_reload_types reload_type)
> vector_foreach_slot(mpvec, mpp, i){
> if (remember_wwid(mpp->wwid) == 1)
> trigger_paths_udev_change(mpp, true);
> - pr_register_active_paths(mpp, false);
> + pr_register_active_paths(mpp, NULL);
> }
>
> /*
> @@ -4370,8 +4392,8 @@ static int update_map_pr(struct multipath *mpp,
> struct path *pp, unsigned int *n
> *
> * nr_keys_wanted: Only used if nr_keys_needed is 0, so we don't
> know how
> * many keys we currently have. If nr_keys_wanted in non-zero and
> the
> - * number of keys found by the initial call to update_map_pr()
> matches it,
> - * exit early, since we have all the keys we are expecting.
> + * number of keys found by the initial call to update_map_pr() is at
> least
> + * as large as it, exit early, since we have all the keys we are
> expecting.
> *
> * The function returns the number of keys that are registered or 0
> if
> * it's unknown.
> @@ -4394,7 +4416,7 @@ mpath_pr_event_handle(struct path *pp, unsigned
> int nr_keys_needed,
> nr_keys_needed = 1;
> if (update_map_pr(mpp, pp, &nr_keys_needed) !=
> MPATH_PR_SUCCESS)
> return 0;
> - if (nr_keys_wanted && nr_keys_wanted ==
> nr_keys_needed)
> + if (nr_keys_wanted && nr_keys_wanted <=
> nr_keys_needed)
> return nr_keys_needed;
> }
>
> diff --git a/multipathd/main.h b/multipathd/main.h
> index 6d60ee81..85b533cd 100644
> --- a/multipathd/main.h
> +++ b/multipathd/main.h
> @@ -54,5 +54,6 @@ int resize_map(struct multipath *mpp, unsigned long
> long size,
> struct vectors *vecs);
> void set_pr(struct multipath *mpp);
> void unset_pr(struct multipath *mpp);
> -void pr_register_active_paths(struct multipath *mpp, bool
> check_active_nr);
> +void pr_register_active_paths(struct multipath *mpp,
> + const struct vector_s
> *registered_paths);
> #endif /* MAIN_H_INCLUDED */
> diff --git a/multipathd/multipathd.8.in b/multipathd/multipathd.8.in
> index 7ffb8d4c..38a243e3 100644
> --- a/multipathd/multipathd.8.in
> +++ b/multipathd/multipathd.8.in
> @@ -348,6 +348,12 @@ Restores configured queue_without_daemon mode.
> Enable persistent reservation management on $map.
> .
> .TP
> +.B setprstatus map|multipath $map pathlist $pathlist
> +Enable persistent reservation management on $map, and notify
> multipathd of
> +the paths that have been registered, so it doesn't attempt to re-
> register
> +them.
> +.
> +.TP
> .B unsetprstatus map|multipath $map
> Disable persistent reservation management on $map.
> .
