ceph: add additional range check in ceph_fallocate()

If the range is larger than both real file size and limit of
max file size, then return -EFBIG.

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/file.c

@@ -1728,8 +1728,7 @@ static long ceph_fallocate(struct file *file, int mode,
 	struct ceph_file_info *fi = file->private_data;
 	struct inode *inode = file_inode(file);
 	struct ceph_inode_info *ci = ceph_inode(inode);
-	struct ceph_osd_client *osdc =
-		&ceph_inode_to_client(inode)->client->osdc;
+	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 	struct ceph_cap_flush *prealloc_cf;
 	int want, got = 0;
 	int dirty;
@@ -1737,6 +1736,9 @@ static long ceph_fallocate(struct file *file, int mode,
 	loff_t endoff = 0;
 	loff_t size;
 
+	if ((offset + length) > max(i_size_read(inode), fsc->max_file_size))
+		return -EFBIG;
+
 	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
 		return -EOPNOTSUPP;
 
@@ -1760,7 +1762,7 @@ static long ceph_fallocate(struct file *file, int mode,
 		goto unlock;
 	}
 
-	if (ceph_osdmap_flag(osdc, CEPH_OSDMAP_FULL) &&
+	if (ceph_osdmap_flag(&fsc->client->osdc, CEPH_OSDMAP_FULL) &&
 	    !(mode & FALLOC_FL_PUNCH_HOLE)) {
 		ret = -ENOSPC;
 		goto unlock;