ceph: fix incorrect kmalloc size of pagevec mempool

[ Upstream commit 03230ed ]

The kmalloc size of pagevec mempool is incorrectly calculated.
It misses the size of page pointer and only accounts the number for the array.

Fixes: a0102bd ("ceph: move sb->wb_pagevec_pool to be a global mempool")
Signed-off-by: ethanwu <ethanwu@synology.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: ethanwu-syno

fs/ceph/super.c

@@ -961,7 +961,8 @@ static int __init init_caches(void)
 	if (!ceph_mds_request_cachep)
 		goto bad_mds_req;
 
-	ceph_wb_pagevec_pool = mempool_create_kmalloc_pool(10, CEPH_MAX_WRITE_SIZE >> PAGE_SHIFT);
+	ceph_wb_pagevec_pool = mempool_create_kmalloc_pool(10,
+	    (CEPH_MAX_WRITE_SIZE >> PAGE_SHIFT) * sizeof(struct page *));
 	if (!ceph_wb_pagevec_pool)
 		goto bad_pagevec_pool;