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geom(4) mirror: Do not panic on gmirror(8) insert, resize

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Geom_mirror initialization occurs in spurts and the present of a
non-destroyed g_mirror softc does not always indicate that the geom has
launched (i.e., has an sc_provider).

Some gmirror(8) commands (via g_mirror_ctl) depend on a g_mirror's
sc_provider (insert and resize).  For those commands, g_mirror_ctl is
modified to sleep-poll in an interruptible way until the target geom is
either launched or destroyed.

Reviewed by:	markj
Tested by:	markj
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D24780
This commit is contained in:
Conrad Meyer 2020-05-11 22:39:53 +00:00
parent fb3c434ba2
commit 844b743d31
1 changed files with 59 additions and 2 deletions
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61
sys/geom/mirror/g_mirror_ctl.c
View File

@ -44,6 +44,10 @@ __FBSDID("$FreeBSD$");
#include <geom/geom_int.h>
#include <geom/mirror/g_mirror.h>
/*
* Configure, Rebuild, Remove, Deactivate, Forget, and Stop operations do not
* seem to depend on any particular g_mirror initialization state.
*/
static struct g_mirror_softc *
g_mirror_find_device(struct g_class *mp, const char *name)
{
@ -61,6 +65,10 @@ g_mirror_find_device(struct g_class *mp, const char *name)
strcmp(sc->sc_name, name) == 0) {
g_topology_unlock();
sx_xlock(&sc->sc_lock);
if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROY) != 0) {
sx_xunlock(&sc->sc_lock);
return (NULL);
}
return (sc);
}
}
@ -68,6 +76,55 @@ g_mirror_find_device(struct g_class *mp, const char *name)
return (NULL);
}
/* Insert and Resize operations depend on a launched GEOM (sc_provider). */
#define GMFL_VALID_FLAGS (M_WAITOK | M_NOWAIT)
static struct g_mirror_softc *
g_mirror_find_launched_device(struct g_class *mp, const char *name, int flags)
{
struct g_mirror_softc *sc;
int error;
KASSERT((flags & ~GMFL_VALID_FLAGS) == 0 &&
flags != GMFL_VALID_FLAGS && flags != 0,
("%s: Invalid flags %x\n", __func__, (unsigned)flags));
#undef GMFL_VALID_FLAGS
while (true) {
sc = g_mirror_find_device(mp, name);
if (sc == NULL)
return (NULL);
if (sc->sc_provider != NULL)
return (sc);
if (flags & M_NOWAIT) {
sx_xunlock(&sc->sc_lock);
return (NULL);
}
/*
* This is a dumb hack. G_mirror does not expose any real
* wakeup API for observing state changes, and even if it did,
* its "RUNNING" state does not actually reflect all softc
* elements being initialized.
*
* Revamping g_mirror to have a 3rd, ACTUALLY_RUNNING state and
* updating all assertions and sc_state checks is a large work
* and would be easy to introduce regressions.
*
* Revamping g_mirror to have a wakeup for state changes would
* be difficult if one wanted to capture more than just
* sc_state and sc_provider.
*
* For now, just dummy sleep-poll until sc_provider shows up,
* the user cancels, or the g_mirror is destroyed.
*/
error = sx_sleep(&sc, &sc->sc_lock, PRIBIO | PCATCH | PDROP,
"GM:launched", 1);
if (error != 0 && error != EWOULDBLOCK)
return (NULL);
}
__unreachable();
}
static struct g_mirror_disk *
g_mirror_find_disk(struct g_mirror_softc *sc, const char *name)
{
@ -605,7 +662,7 @@ g_mirror_ctl_insert(struct gctl_req *req, struct g_class *mp)
gctl_error(req, "No 'arg%u' argument.", 0);
return;
}
sc = g_mirror_find_device(mp, name);
sc = g_mirror_find_launched_device(mp, name, M_WAITOK);
if (sc == NULL) {
gctl_error(req, "No such device: %s.", name);
return;
@ -847,7 +904,7 @@ g_mirror_ctl_resize(struct gctl_req *req, struct g_class *mp)
gctl_error(req, "Invalid '%s' argument.", "size");
return;
}
sc = g_mirror_find_device(mp, name);
sc = g_mirror_find_launched_device(mp, name, M_WAITOK);
if (sc == NULL) {
gctl_error(req, "No such device: %s.", name);
return;