Fix a bug that caused some /dev entries to continue to exist after

the underlying drive had been hot-unplugged from the system.  Here
is a specific example.  Filesystem code had opened /dev/da1s1e.
Subsequently, the drive was hot-unplugged.  This (correctly) caused
all of the associated /dev/da1* entries to be deleted.  When the
filesystem later realized that the drive was gone it closed the
device, reducing the write-access counts to 0 on the geom providers
for da1s1e, da1s1, and da1.  This caused geom to re-taste the
providers, resulting in the devices being created again.  When the
drive was hot-plugged back in, it resulted in duplicate /dev entries
for da1s1e, da1s1, and da1.

This fix adds a new disk_gone() function which is called by CAM when a
drive goes away.  It orphans all of the providers associated with the
drive, setting an error condition of ENXIO in each one.  In addition,
we prevent a re-taste on last close for writing if an error condition
has been set in the provider.

Sponsored by:   Isilon Systems
Reviewed by:    phk
MFC after:      1 week

1 files changed, 12 insertions, 0 deletions

diff --git a/sys/geom/geom_disk.c b/sys/geom/geom_disk.c
index 42c40bc..75d8fc4 100644
--- a/sys/geom/geom_disk.c
+++ b/sys/geom/geom_disk.c
@@ -419,6 +419,18 @@ disk_destroy(struct disk *dp)
 	g_post_event(g_disk_destroy, dp, M_WAITOK, NULL);
 }
 
+void
+disk_gone(struct disk *dp)
+{
+	struct g_geom *gp;
+	struct g_provider *pp;
+
+	gp = dp->d_geom;
+	if (gp != NULL)
+		LIST_FOREACH(pp, &gp->provider, provider)
+			g_orphan_provider(pp, ENXIO);
+}
+
 static void
 g_kern_disks(void *p, int flag __unused)
 {