afs: Fix key leak in afs_release() and afs_evict_inode()

Fix afs_release() to go through the cleanup part of the function if
FMODE_WRITE is set rather than exiting through vfs_fsync() (which skips the
cleanup).  The cleanup involves discarding the refs on the key used for
file ops and the writeback key record.

Also fix afs_evict_inode() to clean up any left over wb keys attached to
the inode/vnode when it is removed.

Fixes: 5a813276 ("afs: Do better accretion of small writes on newly created content")
Signed-off-by: David Howells <dhowells@redhat.com>

fs/afs/file.c

@@ -170,11 +170,12 @@ int afs_release(struct inode *inode, struct file *file)
 {
 	struct afs_vnode *vnode = AFS_FS_I(inode);
 	struct afs_file *af = file->private_data;
+	int ret = 0;
 
 	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
 
 	if ((file->f_mode & FMODE_WRITE))
-		return vfs_fsync(file, 0);
+		ret = vfs_fsync(file, 0);
 
 	file->private_data = NULL;
 	if (af->wb)
@@ -182,8 +183,8 @@ int afs_release(struct inode *inode, struct file *file)
 	key_put(af->key);
 	kfree(af);
 	afs_prune_wb_keys(vnode);
-	_leave(" = 0");
-	return 0;
+	_leave(" = %d", ret);
+	return ret;
 }
 
 /*

fs/afs/inode.c

@@ -573,6 +573,7 @@ void afs_evict_inode(struct inode *inode)
 	}
 #endif
 
+	afs_prune_wb_keys(vnode);
 	afs_put_permits(rcu_access_pointer(vnode->permit_cache));
 	key_put(vnode->silly_key);
 	vnode->silly_key = NULL;