GFS2: Clean up reservation removal

The reservation for an inode should be cleared when it is truncated so
that we can start again at a different offset for future allocations.
We could try and do better than that, by resetting the search based on
where the truncation started from, but this is only a first step.

In addition, there are three callers of gfs2_rs_delete() but only one
of those should really be testing the value of i_writecount. While
we get away with that in the other cases currently, I think it would
be better if we made that test specific to the one case which
requires it.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/bmap.c

@@ -1279,6 +1279,7 @@ do_grow_qunlock:
 
 int gfs2_setattr_size(struct inode *inode, u64 newsize)
 {
+	struct gfs2_inode *ip = GFS2_I(inode);
 	int ret;
 	u64 oldsize;
 
@@ -1294,7 +1295,7 @@ int gfs2_setattr_size(struct inode *inode, u64 newsize)
 
 	inode_dio_wait(inode);
 
-	ret = gfs2_rs_alloc(GFS2_I(inode));
+	ret = gfs2_rs_alloc(ip);
 	if (ret)
 		goto out;
 
@@ -1304,6 +1305,7 @@ int gfs2_setattr_size(struct inode *inode, u64 newsize)
 		goto out;
 	}
 
+	gfs2_rs_deltree(ip->i_res);
 	ret = do_shrink(inode, oldsize, newsize);
 out:
 	put_write_access(inode);