From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Benjamin Marzinski <bmarzins@redhat.com>

Date: Fri, 7 Oct 2022 12:35:40 -0500

Subject: [PATCH] libmultipath: fix queue_mode feature handling

device-mapper is not able to change the queue_mode on a table reload.

Make sure that when multipath sets up the map, both on regular reloads

and reconfigures, it keeps the queue_mode the same.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>

Reviewed-by: Martin Wilck <mwilck@suse.com>

---

 libmultipath/configure.c   |  4 +++

 libmultipath/dmparser.c    |  2 ++

 libmultipath/propsel.c     | 55 ++++++++++++++++++++++++++++++++++++++

 libmultipath/structs.h     |  7 +++++

 multipath/multipath.conf.5 |  7 +++--

 5 files changed, 73 insertions(+), 2 deletions(-)

diff --git a/libmultipath/configure.c b/libmultipath/configure.c

index 70049f47..cc778a22 100644

--- a/libmultipath/configure.c

+++ b/libmultipath/configure.c

@@ -1118,6 +1118,7 @@ int coalesce_paths (struct vectors *vecs, vector mpvec, char *refwwid,

 	struct config *conf = NULL;

 	int allow_queueing;

 	struct bitfield *size_mismatch_seen;

+	struct multipath * cmpp;

 	/* ignore refwwid if it's empty */

 	if (refwwid && !strlen(refwwid))

@@ -1227,6 +1228,9 @@ int coalesce_paths (struct vectors *vecs, vector mpvec, char *refwwid,

 		}

 		verify_paths(mpp);

+		cmpp = find_mp_by_wwid(curmp, mpp->wwid);

+		if (cmpp)

+			mpp->queue_mode = cmpp->queue_mode;

 		if (setup_map(mpp, &params, vecs)) {

 			remove_map(mpp, vecs->pathvec, NULL);

 			continue;

diff --git a/libmultipath/dmparser.c b/libmultipath/dmparser.c

index bc311421..16377c54 100644

--- a/libmultipath/dmparser.c

+++ b/libmultipath/dmparser.c

@@ -152,6 +152,8 @@ int disassemble_map(const struct _vector *pathvec,

 		FREE(word);

 	}

+	mpp->queue_mode = strstr(mpp->features, "queue_mode bio") ?

+			  QUEUE_MODE_BIO : QUEUE_MODE_RQ;

 	/*

 	 * hwhandler

diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c

index 2b47f5f8..9dea6f92 100644

--- a/libmultipath/propsel.c

+++ b/libmultipath/propsel.c

@@ -27,6 +27,7 @@

 #include "strbuf.h"

 #include <inttypes.h>

 #include <libudev.h>

+#include <ctype.h>

 pgpolicyfn *pgpolicies[] = {

 	NULL,

@@ -414,6 +415,59 @@ void reconcile_features_with_options(const char *id, char **features, int* no_pa

 	}

 }

+static void reconcile_features_with_queue_mode(struct multipath *mp)

+{

+	char *space = NULL, *val = NULL, *mode_str = NULL, *feat;

+	int features_mode = QUEUE_MODE_UNDEF;

+

+	if (!mp->features)

+		return;

+

+	pthread_cleanup_push(cleanup_free_ptr, &space);

+	pthread_cleanup_push(cleanup_free_ptr, &val;;

+	pthread_cleanup_push(cleanup_free_ptr, &mode_str);

+

+	if (!(feat = strstr(mp->features, "queue_mode")) ||

+	    feat == mp->features || !isspace(*(feat - 1)) ||

+	    sscanf(feat, "queue_mode%m[ \f\n\r\t\v]%ms", &space, &val) != 2)

+		goto sync_mode;

+	if (asprintf(&mode_str, "queue_mode%s%s", space, val) < 0) {

+		condlog(1, "failed to allocate space for queue_mode feature string");

+		mode_str = NULL; /* value undefined on failure */

+		goto exit;

+	}

+

+	if (!strcmp(val, "rq") || !strcmp(val, "mq"))

+		features_mode = QUEUE_MODE_RQ;

+	else if (!strcmp(val, "bio"))

+		features_mode = QUEUE_MODE_BIO;

+	if (features_mode == QUEUE_MODE_UNDEF) {

+		condlog(2, "%s: ignoring invalid feature '%s'",

+			mp->alias, mode_str);

+		goto sync_mode;

+	}

+

+	if (mp->queue_mode == QUEUE_MODE_UNDEF)

+		mp->queue_mode = features_mode;

+	if (mp->queue_mode == features_mode)

+		goto exit;

+

+	condlog(2,

+		"%s: ignoring feature '%s' because queue_mode is set to '%s'",

+		mp->alias, mode_str,

+		(mp->queue_mode == QUEUE_MODE_RQ)? "rq" : "bio");

+

+sync_mode:

+	if (mode_str)

+		remove_feature(&mp->features, mode_str);

+	if (mp->queue_mode == QUEUE_MODE_BIO)

+		add_feature(&mp->features, "queue_mode bio");

+exit:

+	pthread_cleanup_pop(1);

+	pthread_cleanup_pop(1);

+	pthread_cleanup_pop(1);

+}

+

 int select_features(struct config *conf, struct multipath *mp)

 {

 	const char *origin;

@@ -429,6 +483,7 @@ out:

 	reconcile_features_with_options(mp->alias, &mp->features,

 					&mp->no_path_retry,

 					&mp->retain_hwhandler);

+	reconcile_features_with_queue_mode(mp);

 	condlog(3, "%s: features = \"%s\" %s", mp->alias, mp->features, origin);

 	return 0;

 }

diff --git a/libmultipath/structs.h b/libmultipath/structs.h

index 8a07d470..b4f75de0 100644

--- a/libmultipath/structs.h

+++ b/libmultipath/structs.h

@@ -170,6 +170,12 @@ enum max_sectors_kb_states {

 	MAX_SECTORS_KB_MIN = 4,  /* can't be smaller than page size */

 };

+enum queue_mode_states {

+	QUEUE_MODE_UNDEF = 0,

+	QUEUE_MODE_BIO,

+	QUEUE_MODE_RQ,

+};

+

 enum scsi_protocol {

 	SCSI_PROTOCOL_FCP = 0,	/* Fibre Channel */

 	SCSI_PROTOCOL_SPI = 1,	/* parallel SCSI */

@@ -387,6 +393,7 @@ struct multipath {

 	int needs_paths_uevent;

 	int ghost_delay;

 	int ghost_delay_tick;

+	int queue_mode;

 	uid_t uid;

 	gid_t gid;

 	mode_t mode;

diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5

index f7de5140..e1a787d4 100644

--- a/multipath/multipath.conf.5

+++ b/multipath/multipath.conf.5

@@ -468,8 +468,11 @@ precedence. See KNOWN ISSUES.

 <mode> can be \fIbio\fR, \fIrq\fR or \fImq\fR, which corresponds to

 bio-based, request-based, and block-multiqueue (blk-mq) request-based,

 respectively.

-The default depends on the kernel parameter \fBdm_mod.use_blk_mq\fR. It is

-\fImq\fR if the latter is set, and \fIrq\fR otherwise.

+Before kernel 4.20 The default depends on the kernel parameter

+\fBdm_mod.use_blk_mq\fR. It is \fImq\fR if the latter is set, and \fIrq\fR

+otherwise. Since kernel 4.20, \fIrq\fR and \fImq\fR both correspond to

+block-multiqueue. Once a multipath device has been created, its queue_mode

+cannot be changed.

 .TP

 The default is: \fB<unset>\fR

 .RE