device-mapper-multipath/SOURCES/0124-libmultipath-enforce-queue_mode-bio-for-nmve-tcp-pat.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Benjamin Marzinski <bmarzins@redhat.com>
Date: Fri, 7 Oct 2022 12:35:44 -0500
Subject: [PATCH] libmultipath: enforce queue_mode bio for nmve:tcp paths
nvme:tcp devices set BLK_MQ_F_BLOCKING (they are the only block devices
which multipath supports that do so), meaning that block_mq expects that
they can block at certain points while servicing a request. However,
due to the way device-mapper sets up its queue, it is not able to set
BLK_MQ_F_BLOCKING when it includes paths that set this flag. Patches
were written to address this issue but they were rejected upstream
https://lore.kernel.org/linux-block/YcH%2FE4JNag0QYYAa@infradead.org/T/#t
The proposed solution was to have multipath use the bio queue_mode for
multipath devices that include nvme:tcp paths.
Multipath devices now automatically add the "queue_mode bio" feature if
they include nvme:tcp paths. If a multipath devices was created with
"queue_mode rq", it will disallow the addition of nvme:tcp paths.
Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Reviewed-by: Martin Wilck <mwilck@suse.com>
---
libmultipath/configure.c | 17 ++++++++++++++++-
libmultipath/structs_vec.c | 7 +++++++
multipath/multipath.conf.5 | 4 +++-
3 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/libmultipath/configure.c b/libmultipath/configure.c
index 8e1bc488..c341793c 100644
--- a/libmultipath/configure.c
+++ b/libmultipath/configure.c
@@ -297,6 +297,7 @@ int setup_map(struct multipath *mpp, char *params, int params_size,
struct vectors *vecs)
{
struct pathgroup * pgp;
+ struct path *pp;
struct config *conf;
int i, n_paths, marginal_pathgroups;
@@ -308,6 +309,14 @@ int setup_map(struct multipath *mpp, char *params, int params_size,
return 1;
}
+ /* Force QUEUE_MODE_BIO for maps with nvme:tcp paths */
+ vector_foreach_slot(mpp->paths, pp, i) {
+ if (pp->bus == SYSFS_BUS_NVME &&
+ pp->sg_id.proto_id == NVME_PROTOCOL_TCP) {
+ mpp->queue_mode = QUEUE_MODE_BIO;
+ break;
+ }
+ }
/*
* free features, selector, and hwhandler properties if they are being reused
*/
@@ -1161,6 +1170,13 @@ int coalesce_paths (struct vectors * vecs, vector newmp, char * refwwid,
continue;
}
+ cmpp = find_mp_by_wwid(curmp, pp1->wwid);
+ if (cmpp && cmpp->queue_mode == QUEUE_MODE_RQ &&
+ pp1->bus == SYSFS_BUS_NVME && pp1->sg_id.proto_id ==
+ NVME_PROTOCOL_TCP) {
+ orphan_path(pp1, "nvme:tcp path not allowed with request queue_mode multipath device");
+ continue;
+ }
/*
* at this point, we know we really got a new mp
*/
@@ -1199,7 +1215,6 @@ int coalesce_paths (struct vectors * vecs, vector newmp, char * refwwid,
}
verify_paths(mpp, vecs);
- cmpp = find_mp_by_wwid(curmp, mpp->wwid);
if (cmpp)
mpp->queue_mode = cmpp->queue_mode;
params[0] = '\0';
diff --git a/libmultipath/structs_vec.c b/libmultipath/structs_vec.c
index 8137ea21..24ac022e 100644
--- a/libmultipath/structs_vec.c
+++ b/libmultipath/structs_vec.c
@@ -68,6 +68,13 @@ int adopt_paths(vector pathvec, struct multipath *mpp)
pp->dev, mpp->alias);
continue;
}
+ if (mpp->queue_mode == QUEUE_MODE_RQ &&
+ pp->bus == SYSFS_BUS_NVME &&
+ pp->sg_id.proto_id == NVME_PROTOCOL_TCP) {
+ condlog(2, "%s: mulitpath device %s created with request queue_mode. Unable to add nvme:tcp paths",
+ pp->dev, mpp->alias);
+ continue;
+ }
condlog(3, "%s: ownership set to %s",
pp->dev, mpp->alias);
pp->mpp = mpp;
diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5
index 1f5a40b6..cb07a62c 100644
--- a/multipath/multipath.conf.5
+++ b/multipath/multipath.conf.5
@@ -462,7 +462,9 @@ 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.
+cannot be changed. \fInvme:tcp\fR paths are only supported in multipath
+devices with queue_mode set to \fIbio\fR. multipath will automatically
+set this when creating a device with \fInvme:tcp\fR paths.
.TP
The default is: \fB<unset>\fR
.RE