[PATCH 5.4 045/203] afs: Fix missing cell comparison in afs_test_super()

Greg Kroah-Hartman
2020-01-16T23:20:56Z

From: David Howells <dhowells@redhat.com>

commit 106bc79843c3c6f4f00753d1f46e54e815f99377 upstream.

Fix missing cell comparison in afs_test_super(). Without this, any pair
volumes that have the same volume ID will share a superblock, no matter the
cell, unless they're in different network namespaces.

Normally, most users will only deal with a single cell and so they won't
see this. Even if they do look into a second cell, they won't see a
problem unless they happen to hit a volume with the same ID as one they've
already got mounted.

Before the patch:

# ls /afs/grand.central.org/archive
linuxdev/ mailman/ moin/ mysql/ pipermail/ stage/ twiki/
# ls /afs/kth.se/
linuxdev/ mailman/ moin/ mysql/ pipermail/ stage/ twiki/
# cat /proc/mounts | grep afs
none /afs afs rw,relatime,dyn,autocell 0 0
#grand.central.org:root.cell /afs/grand.central.org afs ro,relatime 0 0
#grand.central.org:root.archive /afs/grand.central.org/archive afs ro,relatime 0 0
#grand.central.org:root.archive /afs/kth.se afs ro,relatime 0 0

After the patch:

# ls /afs/grand.central.org/archive
linuxdev/ mailman/ moin/ mysql/ pipermail/ stage/ twiki/
# ls /afs/kth.se/
admin/ common/ install/ OldFiles/ service/ system/
bakrestores/ home/ misc/ pkg/ src/ wsadmin/
# cat /proc/mounts | grep afs
none /afs afs rw,relatime,dyn,autocell 0 0
#grand.central.org:root.cell /afs/grand.central.org afs ro,relatime 0 0
#grand.central.org:root.archive /afs/grand.central.org/archive afs ro,relatime 0 0
#kth.se:root.cell /afs/kth.se afs ro,relatime 0 0

Fixes: ^1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Carsten Jacobi <jacobi@de.ibm.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Tested-by: Jonathan Billings <jsbillings@jsbillings.org>
cc: Todd DeSantis <atd@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/afs/super.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -404,6 +404,7 @@ static int afs_test_super(struct super_b
return (as->net_ns == fc->net_ns &&
as->volume &&
as->volume->vid == ctx->volume->vid &&
+ as->cell == ctx->cell &&
!as->dyn_root);
}