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, 1 insertions, 0 deletions

diff --git a/sys/geom/geom_disk.h b/sys/geom/geom_disk.h
index 42f5b60..23719bf 100644
--- a/sys/geom/geom_disk.h
+++ b/sys/geom/geom_disk.h
@@ -95,6 +95,7 @@ struct disk {
 struct disk *disk_alloc(void);
 void disk_create(struct disk *disk, int version);
 void disk_destroy(struct disk *disk);
+void disk_gone(struct disk *disk);
 
 #define DISK_VERSION_00		0x58561059
 #define DISK_VERSION		DISK_VERSION_00