Provide an a_ops->swapfile() implementation for NFS. This will set the NFS socket to SOCK_VMIO and run socket reconnect under PF_MEMALLOC as well as reset SOCK_VMIO before engaging the protocol ->connect() method. PF_MEMALLOC should allow the allocation of struct socket and related objects and the early (re)setting of SOCK_VMIO should allow us to receive the packets required for the TCP connection buildup. (swapping continues over a server reset during heavy network traffic) Signed-off-by: Peter Zijlstra Cc: Trond Myklebust --- fs/Kconfig | 19 +++++++++++++++ fs/nfs/file.c | 10 ++++++++ include/linux/sunrpc/xprt.h | 5 +++- net/sunrpc/sched.c | 7 ++++- net/sunrpc/xprtsock.c | 54 ++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 92 insertions(+), 3 deletions(-) Index: linux-2.6-git/fs/nfs/file.c =================================================================== --- linux-2.6-git.orig/fs/nfs/file.c +++ linux-2.6-git/fs/nfs/file.c @@ -324,6 +324,13 @@ static int nfs_launder_page(struct page return nfs_wb_page(page_file_mapping(page)->host, page); } +#ifdef CONFIG_NFS_SWAP +static int nfs_swapfile(struct address_space *mapping, int enable) +{ + return xs_swapper(NFS_CLIENT(mapping->host)->cl_xprt, enable); +} +#endif + const struct address_space_operations nfs_file_aops = { .readpage = nfs_readpage, .readpages = nfs_readpages, @@ -338,6 +345,9 @@ const struct address_space_operations nf .direct_IO = nfs_direct_IO, #endif .launder_page = nfs_launder_page, +#ifdef CONFIG_NFS_SWAP + .swapfile = nfs_swapfile, +#endif }; static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov, Index: linux-2.6-git/include/linux/sunrpc/xprt.h =================================================================== --- linux-2.6-git.orig/include/linux/sunrpc/xprt.h +++ linux-2.6-git/include/linux/sunrpc/xprt.h @@ -151,7 +151,9 @@ struct rpc_xprt { unsigned int max_reqs; /* total slots */ unsigned long state; /* transport state */ unsigned char shutdown : 1, /* being shut down */ - resvport : 1; /* use a reserved port */ + resvport : 1, /* use a reserved port */ + swapper : 1; /* we're swapping over this + transport */ unsigned int bind_index; /* bind function index */ /* @@ -244,6 +246,7 @@ void xprt_disconnect(struct rpc_xprt * */ struct rpc_xprt * xs_setup_udp(struct sockaddr *addr, size_t addrlen, struct rpc_timeout *to); struct rpc_xprt * xs_setup_tcp(struct sockaddr *addr, size_t addrlen, struct rpc_timeout *to); +int xs_swapper(struct rpc_xprt *xprt, int enable); /* * Reserved bit positions in xprt->state Index: linux-2.6-git/net/sunrpc/sched.c =================================================================== --- linux-2.6-git.orig/net/sunrpc/sched.c +++ linux-2.6-git/net/sunrpc/sched.c @@ -755,7 +755,10 @@ static void rpc_async_schedule(struct wo void *rpc_malloc(struct rpc_task *task, size_t size) { size_t *buf; - gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT; + gfp_t gfp = GFP_NOWAIT; + + if (RPC_IS_SWAPPER(task)) + gfp |= __GFP_EMERGENCY; size += sizeof(size_t); if (size <= RPC_BUFFER_MAXSIZE) @@ -837,7 +840,7 @@ void rpc_init_task(struct rpc_task *task static struct rpc_task * rpc_alloc_task(void) { - return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS); + return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOIO); } static void rpc_free_task(struct rcu_head *rcu) Index: linux-2.6-git/net/sunrpc/xprtsock.c =================================================================== --- linux-2.6-git.orig/net/sunrpc/xprtsock.c +++ linux-2.6-git/net/sunrpc/xprtsock.c @@ -1215,11 +1215,15 @@ static void xs_udp_connect_worker(struct container_of(work, struct sock_xprt, connect_worker.work); struct rpc_xprt *xprt = &transport->xprt; struct socket *sock = transport->sock; + unsigned long pflags = current->flags; int err, status = -EIO; if (xprt->shutdown || !xprt_bound(xprt)) goto out; + if (xprt->swapper) + current->flags |= PF_MEMALLOC; + /* Start by resetting any existing state */ xs_close(xprt); @@ -1257,6 +1261,9 @@ static void xs_udp_connect_worker(struct transport->sock = sock; transport->inet = sk; + if (xprt->swapper) + sk_set_vmio(sk); + write_unlock_bh(&sk->sk_callback_lock); } xs_udp_do_set_buffer_size(xprt); @@ -1264,6 +1271,7 @@ static void xs_udp_connect_worker(struct out: xprt_wake_pending_tasks(xprt, status); xprt_clear_connecting(xprt); + tsk_restore_flags(current, pflags, PF_MEMALLOC); } /* @@ -1302,11 +1310,15 @@ static void xs_tcp_connect_worker(struct container_of(work, struct sock_xprt, connect_worker.work); struct rpc_xprt *xprt = &transport->xprt; struct socket *sock = transport->sock; + unsigned long pflags = current->flags; int err, status = -EIO; if (xprt->shutdown || !xprt_bound(xprt)) goto out; + if (xprt->swapper) + current->flags |= PF_MEMALLOC; + if (!sock) { /* start from scratch */ if ((err = sock_create_kern(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock)) < 0) { @@ -1356,6 +1368,10 @@ static void xs_tcp_connect_worker(struct write_unlock_bh(&sk->sk_callback_lock); } + + if (xprt->swapper) + sk_set_vmio(transport->inet); + /* Tell the socket layer to start connecting... */ xprt->stat.connect_count++; xprt->stat.connect_start = jiffies; @@ -1383,6 +1399,7 @@ out: xprt_wake_pending_tasks(xprt, status); out_clear: xprt_clear_connecting(xprt); + tsk_restore_flags(current, pflags, PF_MEMALLOC); } /** @@ -1642,6 +1659,43 @@ int init_socket_xprt(void) return 0; } +#ifdef CONFIG_SUNRPC_SWAP +#define RPC_BUF_RESERVE_PAGES \ + DIV_ROUND_UP((RPC_MAX_SLOT_TABLE * \ + kobjsize(sizeof(struct rpc_rqst))), \ + PAGE_SIZE) +#define RPC_RESERVE_PAGES (RPC_BUF_RESERVE_PAGES + TX_RESERVE_PAGES) + +/** + * xs_swapper - Tag this transport as being used for swap. + * @xprt: transport to tag + * @enable: enable/disable + * + */ +int xs_swapper(struct rpc_xprt *xprt, int enable) +{ + struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); + int err = 0; + + if (enable) { + /* + * keep one extra sock reference so the reserve won't dip + * when the socket gets reconnected. + */ + sk_adjust_memalloc(1, RPC_RESERVE_PAGES); + sk_set_vmio(transport->inet); + xprt->swapper = 1; + } else if (xprt->swapper) { + xprt->swapper = 0; + sk_clear_vmio(transport->inet); + sk_adjust_memalloc(-1, -RPC_RESERVE_PAGES); + } + + return err; +} +EXPORT_SYMBOL_GPL(xs_swapper); +#endif + /** * cleanup_socket_xprt - remove xprtsock's sysctls * Index: linux-2.6-git/fs/Kconfig =================================================================== --- linux-2.6-git.orig/fs/Kconfig +++ linux-2.6-git/fs/Kconfig @@ -1621,6 +1621,18 @@ config NFS_DIRECTIO causes open() to return EINVAL if a file residing in NFS is opened with the O_DIRECT flag. +config NFS_SWAP + bool "Provide swap over NFS support" + default n + depends on NFS_FS + select SUNRPC_SWAP + help + This option enables swapon to work on files located on NFS mounts. + + For more details, see Documentation/vm_deadlock.txt + + If unsure, say N. + config NFSD tristate "NFS server support" depends on INET @@ -1746,6 +1758,13 @@ config SUNRPC_BIND34 If unsure, say N to get traditional behavior (version 2 rpcbind requests only). +config SUNRPC_SWAP + def_bool n + depends on SUNRPC + select SLAB_FAIR + select NETVM + select SWAP_FILE + config RPCSEC_GSS_KRB5 tristate "Secure RPC: Kerberos V mechanism (EXPERIMENTAL)" depends on SUNRPC && EXPERIMENTAL -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/