PR11861: tolerate null struct bio->bi_vcnt in __bio_ino tapset fn

Jeff Moyer confirms operations such as blkdev_issue_flush
can submit an empty bio.

diff --git a/tapset/ioblock.stp b/tapset/ioblock.stp
index 23f792dc8a10e27555b19deca3e5d5a178db390f..80452e966b01acc01e3c26eb91944007d362dde5 100644 (file)
--- a/tapset/ioblock.stp
+++ b/tapset/ioblock.stp
@@ -17,7 +17,7 @@
 function __bio_ino:long(bio:long)
 %{ /* pure */
     struct bio *bio = (struct bio *)(long)THIS->bio;
-    struct page *bv_page = bio? kread(&(bio->bi_io_vec[0].bv_page)) : NULL;
+    struct page *bv_page = (bio && bio->bi_vcnt) ? kread(&(bio->bi_io_vec[0].bv_page)) : NULL;
     struct address_space *mapping;
     struct inode *host;
     THIS->__retvalue = -1;