On Thu, 2021-11-18 at 16:47 -0600, Benjamin Marzinski wrote:
> A mulitpath device can only be reloaded read/write when all paths are
> read/write. Also, whenever a read-only device is rescanned, the scsi
> subsystem will first unconditionally issue a uevent with DISK_RO=0
> before checking the read-only status, and if it the device is still
> read-only, issuing another uevent with DISK_RO=1. These uevents cause
> pointless reloads when read-only paths are rescanned. To avoid this,
> check to see if all paths are read/write before changing a multipath
> device from read-only to read/write.
>
> Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
> ---
> libmultipath/libmultipath.version | 5 +++++
> libmultipath/sysfs.c | 22 ++++++++++++++++++++++
> libmultipath/sysfs.h | 1 +
> multipathd/main.c | 31
> ++++++++++++++++++++++++++++++-
> 4 files changed, 58 insertions(+), 1 deletion(-)
>
> diff --git a/libmultipath/libmultipath.version
> b/libmultipath/libmultipath.version
> index 58a7d1be..ab4c7e30 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -1440,6 +1440,35 @@ finish_path_init(struct path *pp, struct
> vectors * vecs)
> return -1;
> }
>
> +static bool
> +needs_ro_update(struct multipath *mpp, int ro)
> +{
> + struct pathgroup * pgp;
> + struct path * pp;
> + unsigned int i, j;
> + struct dm_info *dmi = NULL;
> +
> + if (!mpp || ro < 0)
> + return false;
> + dm_get_info(mpp->alias, &dmi);
Why can't you just use mpp->dmi here?
> + if (!dmi) /* assume we do need to reload the device */
> + return true;
Why that? I'd assume that if a DM_DEVICE_INFO ioctl fails on the
device, a RELOAD would almost certainly fail, too.
> + if (dmi->read_only == ro) {
> + free(dmi);
> + return false;
> + }
> + free(dmi);
> + if (ro == 1)
> + return true;
> + vector_foreach_slot (mpp->pg, pgp, i) {
> + vector_foreach_slot (pgp->paths, pp, j) {
> + if (sysfs_get_ro(pp) == 1)
> + return false;
I think you should also return false here if sysfs_get_ro() returns
error.
Regards,
Martin
> + }
> + }
> + return true;
> +}
> +
> static int
> uev_update_path (struct uevent *uev, struct vectors * vecs)
> {
> @@ -1512,7 +1541,7 @@ uev_update_path (struct uevent *uev, struct
> vectors * vecs)
> }
>
> ro = uevent_get_disk_ro(uev);
> - if (mpp && ro >= 0) {
> + if (needs_ro_update(mpp, ro)) {
> condlog(2, "%s: update path write_protect to
> '%d' (uevent)", uev->kernel, ro);
>
> if (mpp->wait_for_udev)
--
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