Commit dad2b015 authored Sep 10, 2014 by Jeff Layton Committed by Trond Myklebust Sep 10, 2014

nfs: fix RCU cl_xprt handling in nfs_swap_activate/deactivate



sparse says:

fs/nfs/file.c:543:60: warning: incorrect type in argument 1 (different address spaces)
fs/nfs/file.c:543:60:    expected struct rpc_xprt *xprt
fs/nfs/file.c:543:60:    got struct rpc_xprt [noderef] <asn:4>*cl_xprt
fs/nfs/file.c:548:53: warning: incorrect type in argument 1 (different address spaces)
fs/nfs/file.c:548:53:    expected struct rpc_xprt *xprt
fs/nfs/file.c:548:53:    got struct rpc_xprt [noderef] <asn:4>*cl_xprt

cl_xprt is RCU-managed, so we need to take care to dereference and use
it while holding the RCU read lock.

Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

parent 08a899d5

fs/nfs/file.c

+14 −2

Original line number	Diff line number	Diff line
		@@ -546,13 +546,25 @@ static int nfs_launder_page(struct page *page)
		static int nfs_swap_activate(struct swap_info_struct sis, struct file file,
		sector_t *span)
		{
		int ret;
		struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);

		*span = sis->pages;
		return xs_swapper(NFS_CLIENT(file->f_mapping->host)->cl_xprt, 1);

		rcu_read_lock();
		ret = xs_swapper(rcu_dereference(clnt->cl_xprt), 1);
		rcu_read_unlock();

		return ret;
		}

		static void nfs_swap_deactivate(struct file *file)
		{
		xs_swapper(NFS_CLIENT(file->f_mapping->host)->cl_xprt, 0);
		struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);

		rcu_read_lock();
		xs_swapper(rcu_dereference(clnt->cl_xprt), 0);
		rcu_read_unlock();
		}
		#endif

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