When NVMe disks are added to the system, no uevent containing the DISK_RO property is generated. As a result, dm-* nodes backed by readonly NVMe disks will not have their RO state set properly. The result looks like this: $ multipath -l eui.00c92c091fd6564424a9376600011bd1 dm-3 NVME,Pure Storage FlashArray size=1.0T features='0' hwhandler='0' wp=rw |-+- policy='service-time 0' prio=0 status=active | `- 0:2:2:72657 nvme0n2 259:4 active undef running `-+- policy='service-time 0' prio=0 status=enabled `- 1:0:2:72657 nvme1n2 259:1 active undef running $ cat /sys/block/dm-3/ro 0 $ cat /sys/block/nvme*n2/ro 1 1 This is not a problem for SCSI disks, since the kernel will emit change uevents containing the DISK_RO property when the disk is added to the system. See the following thread for my initial attempt to fix this issue at the kernel level: https://lore.kernel.org/linux-block/Yib8GqCA5e3SQYty@xxxxxxxxxxxxx/T/#t Fix the issue by picking up the path ro state from sysfs in ev_add_path, setting the mpp->force_readonly accordingly, and changing dm_addmap_create to be aware of mpp->force_readonly. Signed-off-by: Uday Shankar <ushankar@xxxxxxxxxxxxxxx> --- libmultipath/devmapper.c | 2 +- multipathd/main.c | 50 ++++++++++++++++++++++------------------ 2 files changed, 29 insertions(+), 23 deletions(-) diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c index 2507f77f..9819e29b 100644 --- a/libmultipath/devmapper.c +++ b/libmultipath/devmapper.c @@ -540,7 +540,7 @@ int dm_addmap_create (struct multipath *mpp, char * params) int ro; uint16_t udev_flags = build_udev_flags(mpp, 0); - for (ro = 0; ro <= 1; ro++) { + for (ro = mpp->force_readonly ? 1 : 0; ro <= 1; ro++) { int err; if (dm_addmap(DM_DEVICE_CREATE, TGT_MPATH, mpp, params, ro, diff --git a/multipathd/main.c b/multipathd/main.c index f2c0b280..a67865df 100644 --- a/multipathd/main.c +++ b/multipathd/main.c @@ -1130,6 +1130,28 @@ out: return ret; } +static int +sysfs_get_ro (struct path *pp) +{ + int ro; + char buff[3]; /* Either "0\n\0" or "1\n\0" */ + + if (!pp->udev) + return -1; + + if (sysfs_attr_get_value(pp->udev, "ro", buff, sizeof(buff)) <= 0) { + condlog(3, "%s: Cannot read ro attribute in sysfs", pp->dev); + return -1; + } + + if (sscanf(buff, "%d\n", &ro) != 1 || ro < 0 || ro > 1) { + condlog(3, "%s: Cannot parse ro attribute", pp->dev); + return -1; + } + + return ro; +} + /* * returns: * 0: added @@ -1143,6 +1165,7 @@ ev_add_path (struct path * pp, struct vectors * vecs, int need_do_map) int retries = 3; int start_waiter = 0; int ret; + int ro; /* * need path UID to go any further @@ -1207,6 +1230,11 @@ rescan: /* persistent reservation check*/ mpath_pr_event_handle(pp); + /* ro check - if new path is ro, force map to be ro as well */ + ro = sysfs_get_ro(pp); + if (ro == 1) + mpp->force_readonly = 1; + if (!need_do_map) return 0; @@ -1446,28 +1474,6 @@ finish_path_init(struct path *pp, struct vectors * vecs) return -1; } -static int -sysfs_get_ro (struct path *pp) -{ - int ro; - char buff[3]; /* Either "0\n\0" or "1\n\0" */ - - if (!pp->udev) - return -1; - - if (sysfs_attr_get_value(pp->udev, "ro", buff, sizeof(buff)) <= 0) { - condlog(3, "%s: Cannot read ro attribute in sysfs", pp->dev); - return -1; - } - - if (sscanf(buff, "%d\n", &ro) != 1 || ro < 0 || ro > 1) { - condlog(3, "%s: Cannot parse ro attribute", pp->dev); - return -1; - } - - return ro; -} - static bool needs_ro_update(struct multipath *mpp, int ro) { -- 2.25.1 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
