From: NeilBrown Date: Wed, 24 Sep 2014 01:28:32 +0000 (+1000) Subject: NFS/SUNRPC: Remove other deadlock-avoidance mechanisms in nfs_release_page() X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=1aff52562939485e503936e17934be077ffaea53;p=openwrt%2Fstaging%2Fblogic.git 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 Acked-by: Jeff Layton Signed-off-by: Trond Myklebust --- diff --git a/fs/nfs/file.c b/fs/nfs/file.c index 24832d040eb8..6920127c5eb7 100644 --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -476,20 +476,18 @@ static int nfs_release_page(struct page *page, gfp_t gfp) 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 9358c79fd589..fe3441abdbe5 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -821,9 +821,7 @@ void rpc_execute(struct rpc_task *task) 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 2faac4940563..6a4615dd0261 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -205,7 +205,6 @@ xprt_rdma_connect_worker(struct work_struct *work) 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 @@ xprt_rdma_connect_worker(struct work_struct *work) 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 02603ec2460a..3b305ab17afe 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1954,8 +1954,6 @@ static int xs_local_setup_socket(struct sock_xprt *transport) 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 @@ static int xs_local_setup_socket(struct sock_xprt *transport) out: xprt_clear_connecting(xprt); xprt_wake_pending_tasks(xprt, status); - current->flags &= ~PF_FSTRANS; return status; } @@ -2098,8 +2095,6 @@ static void xs_udp_setup_socket(struct work_struct *work) 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 @@ static void xs_udp_setup_socket(struct work_struct *work) out: xprt_clear_connecting(xprt); xprt_wake_pending_tasks(xprt, status); - current->flags &= ~PF_FSTRANS; } /* @@ -2256,8 +2250,6 @@ static void xs_tcp_setup_socket(struct work_struct *work) 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 @@ static void xs_tcp_setup_socket(struct work_struct *work) 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_eagain: out: xprt_clear_connecting(xprt); xprt_wake_pending_tasks(xprt, status); - current->flags &= ~PF_FSTRANS; } /**