NFS/SUNRPC: Remove other deadlock-avoidance mechanisms in nfs_release_page()
Now that nfs_release_page() doesn't block indefinitely, other deadlock
avoidance mechanisms aren't needed.
- it doesn't hurt for kswapd to block occasionally. If it doesn't
want to block it would clear __GFP_WAIT. The current_is_kswapd()
was only added to avoid deadlocks and we have a new approach for
that.
- memory allocation in the SUNRPC layer can very rarely try to
->releasepage() a page it is trying to handle. The deadlock
is removed as nfs_release_page() doesn't block indefinitely.
So we don't need to set PF_FSTRANS for sunrpc network operations any
more.
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 24832d0..6920127c 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -476,20 +476,18 @@
dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
/* Always try to initiate a 'commit' if relevant, but only
- * wait for it if __GFP_WAIT is set and the calling process is
- * allowed to block. Even then, only wait 1 second and only
- * if the 'bdi' is not congested.
+ * wait for it if __GFP_WAIT is set. Even then, only wait 1
+ * second and only if the 'bdi' is not congested.
* Waiting indefinitely can cause deadlocks when the NFS
- * server is on this machine, and there is no particular need
- * to wait extensively here. A short wait has the benefit
- * that someone else can worry about the freezer.
+ * server is on this machine, when a new TCP connection is
+ * needed and in other rare cases. There is no particular
+ * need to wait extensively here. A short wait has the
+ * benefit that someone else can worry about the freezer.
*/
if (mapping) {
struct nfs_server *nfss = NFS_SERVER(mapping->host);
nfs_commit_inode(mapping->host, 0);
if ((gfp & __GFP_WAIT) &&
- !current_is_kswapd() &&
- !(current->flags & PF_FSTRANS) &&
!bdi_write_congested(&nfss->backing_dev_info)) {
wait_on_page_bit_killable_timeout(page, PG_private,
HZ);
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 9358c79..fe3441a 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -821,9 +821,7 @@
static void rpc_async_schedule(struct work_struct *work)
{
- current->flags |= PF_FSTRANS;
__rpc_execute(container_of(work, struct rpc_task, u.tk_work));
- current->flags &= ~PF_FSTRANS;
}
/**
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 2faac49..6a4615d 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -205,7 +205,6 @@
struct rpc_xprt *xprt = &r_xprt->xprt;
int rc = 0;
- current->flags |= PF_FSTRANS;
xprt_clear_connected(xprt);
dprintk("RPC: %s: %sconnect\n", __func__,
@@ -216,7 +215,6 @@
dprintk("RPC: %s: exit\n", __func__);
xprt_clear_connecting(xprt);
- current->flags &= ~PF_FSTRANS;
}
/*
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 02603ec..3b305ab1 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1954,8 +1954,6 @@
struct socket *sock;
int status = -EIO;
- current->flags |= PF_FSTRANS;
-
clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
status = __sock_create(xprt->xprt_net, AF_LOCAL,
SOCK_STREAM, 0, &sock, 1);
@@ -1995,7 +1993,6 @@
out:
xprt_clear_connecting(xprt);
xprt_wake_pending_tasks(xprt, status);
- current->flags &= ~PF_FSTRANS;
return status;
}
@@ -2098,8 +2095,6 @@
struct socket *sock = transport->sock;
int status = -EIO;
- current->flags |= PF_FSTRANS;
-
/* Start by resetting any existing state */
xs_reset_transport(transport);
sock = xs_create_sock(xprt, transport,
@@ -2119,7 +2114,6 @@
out:
xprt_clear_connecting(xprt);
xprt_wake_pending_tasks(xprt, status);
- current->flags &= ~PF_FSTRANS;
}
/*
@@ -2256,8 +2250,6 @@
struct rpc_xprt *xprt = &transport->xprt;
int status = -EIO;
- current->flags |= PF_FSTRANS;
-
if (!sock) {
clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
sock = xs_create_sock(xprt, transport,
@@ -2305,7 +2297,6 @@
case -EINPROGRESS:
case -EALREADY:
xprt_clear_connecting(xprt);
- current->flags &= ~PF_FSTRANS;
return;
case -EINVAL:
/* Happens, for instance, if the user specified a link
@@ -2323,7 +2314,6 @@
out:
xprt_clear_connecting(xprt);
xprt_wake_pending_tasks(xprt, status);
- current->flags &= ~PF_FSTRANS;
}
/**