CacheFiles: Update IMA counters when using dentry_open

When IMA is active, using dentry_open without updating the
IMA counters will result in free/open imbalance errors when
fput is eventually called.
Signed-off-by: NMarc Dionne <marc.c.dionne@gmail.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/cachefiles/rdwr.c

@@ -11,6 +11,7 @@
 
 #include <linux/mount.h>
 #include <linux/file.h>
+#include <linux/ima.h>
 #include "internal.h"
 
 /*
@@ -922,6 +923,7 @@ int cachefiles_write_page(struct fscache_storage *op, struct page *page)
 	if (IS_ERR(file)) {
 		ret = PTR_ERR(file);
 	} else {
+		ima_counts_get(file);
 		ret = -EIO;
 		if (file->f_op->write) {
 			pos = (loff_t) page->index << PAGE_SHIFT;