CA-86862-blkback-size-write-panic.patch

# HG changeset patch
# Parent ad0e3837a89655092989bb0393386e6db1968902
CA-86862: Fix panic when writing to /sys/kernel/blkback-pools/<pool_id>/size and turn off write permissions for that file.

diff -r ad0e3837a896 drivers/xen/blkback/blkback.c
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -945,7 +945,7 @@ blkback_page_pool_show_size(struct blkba
 }
 
 static struct pool_attribute blkback_page_pool_attr_size =
-	__ATTR(size, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH,
+	__ATTR(size, S_IRUSR|S_IRGRP|S_IROTH,
 	       blkback_page_pool_show_size, NULL);
 
 static ssize_t
@@ -1002,7 +1002,7 @@ blkback_page_pool_store_attr(struct kobj
 	struct blkback_page_pool *pool = kobj_to_pool(kobj);
 	struct pool_attribute *attr = kattr_to_pool_attr(kattr);
 
-	if (attr->show)
+	if (attr->store)
 		return attr->store(pool, buf, size);
 
 	return -EIO;