2014-09-10 13:04:04

by Jeff Layton

[permalink] [raw]
Subject: [PATCH] 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 <[email protected]>
Signed-off-by: Jeff Layton <[email protected]>
---
fs/nfs/file.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 524dd80d1898..fe7f6126a7d2 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -539,13 +539,25 @@ 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

--
1.9.3