Some vendor kernels (e.g. SUSE) have supported loading multipath maps without valid paths for a long time. Without that feature, problems can occur in failover scenarios when multipathd tries to (re)load maps after device failure/removal, because multipathd's attempts to reload the configuration may fail unnecessarily. The discussion in the kernel community is ongoing (see e.g. https://patchwork.kernel.org/patch/4579551/). One corner case of this is creation of a map with only failed paths. Such maps can be created if the kernel patch mentioned above is applied. The current udev rules for dm-multipath can't detect this situation. This patch fixes that by setting DM_SUBSYSTEM_UDEV_FLAG2, which is already used for the "map reload" case with no valid paths. Thus no additional udev rules are required to detect this situation. Signed-off-by: Martin Wilck <mwilck@xxxxxxxx> --- libmultipath/devmapper.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c index e701e806..7a3390a7 100644 --- a/libmultipath/devmapper.c +++ b/libmultipath/devmapper.c @@ -300,12 +300,14 @@ dm_device_remove (const char *name, int needsync, int deferred_remove) { static int dm_addmap (int task, const char *target, struct multipath *mpp, - char * params, int ro, int skip_kpartx) { + char * params, int ro, uint16_t udev_flags) { int r = 0; struct dm_task *dmt; char *prefixed_uuid = NULL; uint32_t cookie = 0; - uint16_t udev_flags = DM_UDEV_DISABLE_LIBRARY_FALLBACK | ((skip_kpartx == SKIP_KPARTX_ON)? MPATH_UDEV_NO_KPARTX_FLAG : 0); + + /* Need to add this here to allow 0 to be passed in udev_flags */ + udev_flags |= DM_UDEV_DISABLE_LIBRARY_FALLBACK; if (!(dmt = libmp_dm_task_create (task))) return 0; @@ -371,15 +373,27 @@ addout: return r; } +static uint16_t build_udev_flags(const struct multipath *mpp, int reload) +{ + /* DM_UDEV_DISABLE_LIBRARY_FALLBACK is added in dm_addmap */ + return (mpp->skip_kpartx == SKIP_KPARTX_ON ? + MPATH_UDEV_NO_KPARTX_FLAG : 0) | + (mpp->nr_active == 0 ? + MPATH_UDEV_NO_PATHS_FLAG : 0) | + (reload && !mpp->force_udev_reload ? + MPATH_UDEV_RELOAD_FLAG : 0); +} + 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++) { int err; if (dm_addmap(DM_DEVICE_CREATE, TGT_MPATH, mpp, params, ro, - mpp->skip_kpartx)) + udev_flags)) return 1; /* * DM_DEVICE_CREATE is actually DM_DEV_CREATE + DM_TABLE_LOAD. @@ -405,11 +419,7 @@ int dm_addmap_create (struct multipath *mpp, char * params) int dm_addmap_reload(struct multipath *mpp, char *params, int flush) { int r = 0; - uint16_t udev_flags = ((mpp->force_udev_reload)? - 0 : MPATH_UDEV_RELOAD_FLAG) | - ((mpp->skip_kpartx == SKIP_KPARTX_ON)? - MPATH_UDEV_NO_KPARTX_FLAG : 0) | - ((mpp->nr_active)? 0 : MPATH_UDEV_NO_PATHS_FLAG); + uint16_t udev_flags = build_udev_flags(mpp, 1); /* * DM_DEVICE_RELOAD cannot wait on a cookie, as @@ -419,12 +429,12 @@ int dm_addmap_reload(struct multipath *mpp, char *params, int flush) */ if (!mpp->force_readonly) r = dm_addmap(DM_DEVICE_RELOAD, TGT_MPATH, mpp, params, - ADDMAP_RW, SKIP_KPARTX_OFF); + ADDMAP_RW, 0); if (!r) { if (!mpp->force_readonly && errno != EROFS) return 0; r = dm_addmap(DM_DEVICE_RELOAD, TGT_MPATH, mpp, - params, ADDMAP_RO, SKIP_KPARTX_OFF); + params, ADDMAP_RO, 0); } if (r) r = dm_simplecmd(DM_DEVICE_RESUME, mpp->alias, !flush, -- 2.14.0 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
