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authorJeff Layton <jlayton@poochiereds.net>2015-06-03 22:14:25 +0200
committerTrond Myklebust <trond.myklebust@primarydata.com>2015-06-11 00:26:14 +0200
commit3c87ef6efb40f0e339d705c194b2224f854ec38e (patch)
tree2878ea261637cf6c85ab69b9cbde70a036b1e3a2 /fs/nfs/file.c
parentSUNRPC: Fix a backchannel race (diff)
downloadlinux-3c87ef6efb40f0e339d705c194b2224f854ec38e.tar.xz
linux-3c87ef6efb40f0e339d705c194b2224f854ec38e.zip
sunrpc: keep a count of swapfiles associated with the rpc_clnt
Jerome reported seeing a warning pop when working with a swapfile on NFS. The nfs_swap_activate can end up calling sk_set_memalloc while holding the rcu_read_lock and that function can sleep. To fix that, we need to take a reference to the xprt while holding the rcu_read_lock, set the socket up for swapping and then drop that reference. But, xprt_put is not exported and having NFS deal with the underlying xprt is a bit of layering violation anyway. Fix this by adding a set of activate/deactivate functions that take a rpc_clnt pointer instead of an rpc_xprt, and have nfs_swap_activate and nfs_swap_deactivate call those. Also, add a per-rpc_clnt atomic counter to keep track of the number of active swapfiles associated with it. When the counter does a 0->1 transition, we enable swapping on the xprt, when we do a 1->0 transition we disable swapping on it. This also allows us to be a bit more selective with the RPC_TASK_SWAPPER flag. If non-swapper and swapper clnts are sharing a xprt, then we only need to flag the tasks from the swapper clnt with that flag. Acked-by: Mel Gorman <mgorman@suse.de> Reported-by: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> Reviewed-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'fs/nfs/file.c')
-rw-r--r--fs/nfs/file.c15
1 files changed, 2 insertions, 13 deletions
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 8b8d83a526ce..cc4fa1ed61fc 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -555,31 +555,22 @@ static int nfs_launder_page(struct page *page)
return nfs_wb_page(inode, page);
}
-#ifdef CONFIG_NFS_SWAP
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;
- rcu_read_lock();
- ret = xs_swapper(rcu_dereference(clnt->cl_xprt), 1);
- rcu_read_unlock();
-
- return ret;
+ return rpc_clnt_swap_activate(clnt);
}
static void nfs_swap_deactivate(struct file *file)
{
struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
- rcu_read_lock();
- xs_swapper(rcu_dereference(clnt->cl_xprt), 0);
- rcu_read_unlock();
+ rpc_clnt_swap_deactivate(clnt);
}
-#endif
const struct address_space_operations nfs_file_aops = {
.readpage = nfs_readpage,
@@ -596,10 +587,8 @@ const struct address_space_operations nfs_file_aops = {
.launder_page = nfs_launder_page,
.is_dirty_writeback = nfs_check_dirty_writeback,
.error_remove_page = generic_error_remove_page,
-#ifdef CONFIG_NFS_SWAP
.swap_activate = nfs_swap_activate,
.swap_deactivate = nfs_swap_deactivate,
-#endif
};
/*