ceph: check that the new inode size is within limits in ceph_fallocate()

Currently the ceph client doesn't respect the rlimit in fallocate.  This
means that a user can allocate a file with size > RLIMIT_FSIZE.  This
patch adds the call to inode_newsize_ok() to verify filesystem limits and
ulimits.  This should make ceph successfully run xfstest generic/228.

Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/file.c

@@ -1671,8 +1671,12 @@ static long ceph_fallocate(struct file *file, int mode,
 	}
 
 	size = i_size_read(inode);
-	if (!(mode & FALLOC_FL_KEEP_SIZE))
+	if (!(mode & FALLOC_FL_KEEP_SIZE)) {
 		endoff = offset + length;
+		ret = inode_newsize_ok(inode, endoff);
+		if (ret)
+			goto unlock;
+	}
 
 	if (fi->fmode & CEPH_FILE_MODE_LAZY)
 		want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;