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Subject[PATCH 09/11] nfs: enable swap on NFS
Date
Implement the new swapfile a_ops for NFS and hook up ->direct_IO. This
will set the NFS socket to SOCK_MEMALLOC and run socket reconnect
under PF_MEMALLOC as well as reset SOCK_MEMALLOC 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_MEMALLOC should allow us
to receive the packets required for the TCP connection buildup.

[dfeng@redhat.com: Fix handling of multiple swap files]
[a.p.zijlstra@chello.nl: Original patch]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
fs/nfs/Kconfig | 8 ++++
fs/nfs/direct.c | 94 +++++++++++++++++++++++++++++--------------
fs/nfs/file.c | 22 +++++++++-
include/linux/nfs_fs.h | 4 +-
include/linux/sunrpc/xprt.h | 3 +
net/sunrpc/Kconfig | 5 ++
net/sunrpc/clnt.c | 2 +
net/sunrpc/sched.c | 7 ++-
net/sunrpc/xprtsock.c | 53 ++++++++++++++++++++++++
9 files changed, 161 insertions(+), 37 deletions(-)
diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index dbcd821..7c3b921 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -74,6 +74,14 @@ config NFS_V4

If unsure, say Y.

+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.
+
config NFS_V4_1
bool "NFS client support for NFSv4.1 (EXPERIMENTAL)"
depends on NFS_FS && NFS_V4 && EXPERIMENTAL
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 1940f1a..822a53a 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -112,17 +112,28 @@ static inline int put_dreq(struct nfs_direct_req *dreq)
* @nr_segs: size of iovec array
*
* The presence of this routine in the address space ops vector means
- * the NFS client supports direct I/O. However, we shunt off direct
- * read and write requests before the VFS gets them, so this method
- * should never be called.
+ * the NFS client supports direct I/O. However, for most direct IO, we
+ * shunt off direct read and write requests before the VFS gets them,
+ * so this method is only ever called for swap.
*/
ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
{
+#ifndef CONFIG_NFS_SWAP
dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
iocb->ki_filp->f_path.dentry->d_name.name,
(long long) pos, nr_segs);

return -EINVAL;
+#else
+ VM_BUG_ON(iocb->ki_left != PAGE_SIZE);
+ VM_BUG_ON(iocb->ki_nbytes != PAGE_SIZE);
+
+ if (rw == READ || rw == KERNEL_READ)
+ return nfs_file_direct_read(iocb, iov, nr_segs, pos,
+ rw == READ ? true : false);
+ return nfs_file_direct_write(iocb, iov, nr_segs, pos,
+ rw == WRITE ? true : false);
+#endif /* CONFIG_NFS_SWAP */
}

static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
@@ -281,7 +292,7 @@ static const struct rpc_call_ops nfs_read_direct_ops = {
*/
static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
const struct iovec *iov,
- loff_t pos)
+ loff_t pos, bool uio)
{
struct nfs_open_context *ctx = dreq->ctx;
struct inode *inode = ctx->dentry->d_inode;
@@ -315,13 +326,22 @@ static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
if (unlikely(!data))
break;

- down_read(&current->mm->mmap_sem);
- result = get_user_pages(current, current->mm, user_addr,
- data->npages, 1, 0, data->pagevec, NULL);
- up_read(&current->mm->mmap_sem);
- if (result < 0) {
- nfs_readdata_free(data);
- break;
+ if (uio) {
+ down_read(&current->mm->mmap_sem);
+ result = get_user_pages(current, current->mm, user_addr,
+ data->npages, 1, 0, data->pagevec, NULL);
+ up_read(&current->mm->mmap_sem);
+ if (result < 0) {
+ nfs_readdata_free(data);
+ break;
+ }
+ } else {
+ WARN_ON(data->npages != 1);
+ result = get_kernel_page(user_addr, 1, data->pagevec);
+ if (WARN_ON(result != 1)) {
+ nfs_readdata_free(data);
+ break;
+ }
}
if ((unsigned)result < data->npages) {
bytes = result * PAGE_SIZE;
@@ -389,7 +409,7 @@ static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
const struct iovec *iov,
unsigned long nr_segs,
- loff_t pos)
+ loff_t pos, bool uio)
{
ssize_t result = -EINVAL;
size_t requested_bytes = 0;
@@ -399,7 +419,7 @@ static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,

for (seg = 0; seg < nr_segs; seg++) {
const struct iovec *vec = &iov[seg];
- result = nfs_direct_read_schedule_segment(dreq, vec, pos);
+ result = nfs_direct_read_schedule_segment(dreq, vec, pos, uio);
if (result < 0)
break;
requested_bytes += result;
@@ -423,7 +443,7 @@ static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
}

static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
- unsigned long nr_segs, loff_t pos)
+ unsigned long nr_segs, loff_t pos, bool uio)
{
ssize_t result = -ENOMEM;
struct inode *inode = iocb->ki_filp->f_mapping->host;
@@ -441,7 +461,7 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
if (!is_sync_kiocb(iocb))
dreq->iocb = iocb;

- result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
+ result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos, uio);
if (!result)
result = nfs_direct_wait(dreq);
out_release:
@@ -712,7 +732,8 @@ static const struct rpc_call_ops nfs_write_direct_ops = {
*/
static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
const struct iovec *iov,
- loff_t pos, int sync)
+ loff_t pos, int sync,
+ bool uio)
{
struct nfs_open_context *ctx = dreq->ctx;
struct inode *inode = ctx->dentry->d_inode;
@@ -746,13 +767,22 @@ static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
if (unlikely(!data))
break;

- down_read(&current->mm->mmap_sem);
- result = get_user_pages(current, current->mm, user_addr,
- data->npages, 0, 0, data->pagevec, NULL);
- up_read(&current->mm->mmap_sem);
- if (result < 0) {
- nfs_writedata_free(data);
- break;
+ if (uio) {
+ down_read(&current->mm->mmap_sem);
+ result = get_user_pages(current, current->mm, user_addr,
+ data->npages, 0, 0, data->pagevec, NULL);
+ up_read(&current->mm->mmap_sem);
+ if (result < 0) {
+ nfs_writedata_free(data);
+ break;
+ }
+ } else {
+ WARN_ON(data->npages != 1);
+ result = get_kernel_page(user_addr, 0, data->pagevec);
+ if (WARN_ON(result != 1)) {
+ nfs_writedata_free(data);
+ break;
+ }
}
if ((unsigned)result < data->npages) {
bytes = result * PAGE_SIZE;
@@ -824,7 +854,8 @@ static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
const struct iovec *iov,
unsigned long nr_segs,
- loff_t pos, int sync)
+ loff_t pos, int sync,
+ bool uio)
{
ssize_t result = 0;
size_t requested_bytes = 0;
@@ -835,7 +866,7 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
for (seg = 0; seg < nr_segs; seg++) {
const struct iovec *vec = &iov[seg];
result = nfs_direct_write_schedule_segment(dreq, vec,
- pos, sync);
+ pos, sync, uio);
if (result < 0)
break;
requested_bytes += result;
@@ -860,7 +891,7 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,

static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos,
- size_t count)
+ size_t count, bool uio)
{
ssize_t result = -ENOMEM;
struct inode *inode = iocb->ki_filp->f_mapping->host;
@@ -884,7 +915,8 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
if (!is_sync_kiocb(iocb))
dreq->iocb = iocb;

- result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
+ result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos,
+ sync, uio);
if (!result)
result = nfs_direct_wait(dreq);
out_release:
@@ -915,7 +947,7 @@ out:
* cache.
*/
ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
- unsigned long nr_segs, loff_t pos)
+ unsigned long nr_segs, loff_t pos, bool uio)
{
ssize_t retval = -EINVAL;
struct file *file = iocb->ki_filp;
@@ -940,7 +972,7 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,

task_io_account_read(count);

- retval = nfs_direct_read(iocb, iov, nr_segs, pos);
+ retval = nfs_direct_read(iocb, iov, nr_segs, pos, uio);
if (retval > 0)
iocb->ki_pos = pos + retval;

@@ -971,7 +1003,7 @@ out:
* is no atomic O_APPEND write facility in the NFS protocol.
*/
ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
- unsigned long nr_segs, loff_t pos)
+ unsigned long nr_segs, loff_t pos, bool uio)
{
ssize_t retval = -EINVAL;
struct file *file = iocb->ki_filp;
@@ -1003,7 +1035,7 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,

task_io_account_write(count);

- retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
+ retval = nfs_direct_write(iocb, iov, nr_segs, pos, count, uio);

if (retval > 0)
iocb->ki_pos = pos + retval;
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 2a0a750..68a563b 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -188,7 +188,7 @@ nfs_file_read(struct kiocb *iocb, const struct iovec *iov,
ssize_t result;

if (iocb->ki_filp->f_flags & O_DIRECT)
- return nfs_file_direct_read(iocb, iov, nr_segs, pos);
+ return nfs_file_direct_read(iocb, iov, nr_segs, pos, true);

dprintk("NFS: read(%s/%s, %lu@%lu)\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
@@ -487,6 +487,20 @@ 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)
+{
+ *span = sis->pages;
+ return xs_swapper(NFS_CLIENT(file->f_mapping->host)->cl_xprt, 1);
+}
+
+static void nfs_swap_deactivate(struct file *file)
+{
+ xs_swapper(NFS_CLIENT(file->f_mapping->host)->cl_xprt, 0);
+}
+#endif
+
const struct address_space_operations nfs_file_aops = {
.readpage = nfs_readpage,
.readpages = nfs_readpages,
@@ -501,6 +515,10 @@ const struct address_space_operations nfs_file_aops = {
.migratepage = nfs_migrate_page,
.launder_page = nfs_launder_page,
.error_remove_page = generic_error_remove_page,
+#ifdef CONFIG_NFS_SWAP
+ .swap_activate = nfs_swap_activate,
+ .swap_deactivate = nfs_swap_deactivate,
+#endif
};

/*
@@ -573,7 +591,7 @@ static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
size_t count = iov_length(iov, nr_segs);

if (iocb->ki_filp->f_flags & O_DIRECT)
- return nfs_file_direct_write(iocb, iov, nr_segs, pos);
+ return nfs_file_direct_write(iocb, iov, nr_segs, pos, true);

dprintk("NFS: write(%s/%s, %lu@%Ld)\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 8c29950..4dc0f8c 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -455,10 +455,10 @@ extern ssize_t nfs_direct_IO(int, struct kiocb *, const struct iovec *, loff_t,
unsigned long);
extern ssize_t nfs_file_direct_read(struct kiocb *iocb,
const struct iovec *iov, unsigned long nr_segs,
- loff_t pos);
+ loff_t pos, bool uio);
extern ssize_t nfs_file_direct_write(struct kiocb *iocb,
const struct iovec *iov, unsigned long nr_segs,
- loff_t pos);
+ loff_t pos, bool uio);

/*
* linux/fs/nfs/dir.c
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 15518a1..62e6259 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -174,6 +174,8 @@ struct rpc_xprt {
unsigned long state; /* transport state */
unsigned char shutdown : 1, /* being shut down */
resvport : 1; /* use a reserved port */
+ unsigned int swapper; /* we're swapping over this
+ transport */
unsigned int bind_index; /* bind function index */

/*
@@ -311,6 +313,7 @@ void xprt_release_rqst_cong(struct rpc_task *task);
void xprt_disconnect_done(struct rpc_xprt *xprt);
void xprt_force_disconnect(struct rpc_xprt *xprt);
void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie);
+int xs_swapper(struct rpc_xprt *xprt, int enable);

/*
* Reserved bit positions in xprt->state
diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig
index ffd243d..0e9d340 100644
--- a/net/sunrpc/Kconfig
+++ b/net/sunrpc/Kconfig
@@ -21,6 +21,11 @@ config SUNRPC_XPRT_RDMA

If unsure, say N.

+config SUNRPC_SWAP
+ bool
+ depends on SUNRPC
+ select NETVM
+
config RPCSEC_GSS_KRB5
tristate "Secure RPC: Kerberos V mechanism"
depends on SUNRPC && CRYPTO
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index f0268ea..277fb86 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -594,6 +594,8 @@ void rpc_task_set_client(struct rpc_task *task, struct rpc_clnt *clnt)
atomic_inc(&clnt->cl_count);
if (clnt->cl_softrtry)
task->tk_flags |= RPC_TASK_SOFT;
+ if (task->tk_client->cl_xprt->swapper)
+ task->tk_flags |= RPC_TASK_SWAPPER;
/* Add to the client's list of all tasks */
spin_lock(&clnt->cl_lock);
list_add_tail(&task->tk_task, &clnt->cl_tasks);
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 3341d89..cb7ef6c 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -771,7 +771,10 @@ static void rpc_async_schedule(struct work_struct *work)
void *rpc_malloc(struct rpc_task *task, size_t size)
{
struct rpc_buffer *buf;
- gfp_t gfp = RPC_IS_SWAPPER(task) ? GFP_ATOMIC : GFP_NOWAIT;
+ gfp_t gfp = GFP_NOWAIT;
+
+ if (RPC_IS_SWAPPER(task))
+ gfp |= __GFP_MEMALLOC;

size += sizeof(struct rpc_buffer);
if (size <= RPC_BUFFER_MAXSIZE)
@@ -845,7 +848,7 @@ static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *ta
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);
}

/*
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 55472c4..e3c6a70 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1930,6 +1930,45 @@ out:
xprt_wake_pending_tasks(xprt, status);
}

+#ifdef CONFIG_SUNRPC_SWAP
+static void xs_set_memalloc(struct rpc_xprt *xprt)
+{
+ struct sock_xprt *transport = container_of(xprt, struct sock_xprt,
+ xprt);
+
+ if (xprt->swapper)
+ sk_set_memalloc(transport->inet);
+}
+
+/**
+ * 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) {
+ xprt->swapper++;
+ xs_set_memalloc(xprt);
+ } else if (xprt->swapper) {
+ xprt->swapper--;
+ sk_clear_memalloc(transport->inet);
+ }
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(xs_swapper);
+#else
+static void xs_set_memalloc(struct rpc_xprt *xprt)
+{
+}
+#endif
+
static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
{
struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
@@ -1954,6 +1993,8 @@ static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
transport->sock = sock;
transport->inet = sk;

+ xs_set_memalloc(xprt);
+
write_unlock_bh(&sk->sk_callback_lock);
}
xs_udp_do_set_buffer_size(xprt);
@@ -1965,11 +2006,15 @@ static void xs_udp_setup_socket(struct work_struct *work)
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 status = -EIO;

if (xprt->shutdown)
goto out;

+ if (xprt->swapper)
+ current->flags |= PF_MEMALLOC;
+
/* Start by resetting any existing state */
xs_reset_transport(transport);
sock = xs_create_sock(xprt, transport,
@@ -1988,6 +2033,7 @@ static void xs_udp_setup_socket(struct work_struct *work)
out:
xprt_clear_connecting(xprt);
xprt_wake_pending_tasks(xprt, status);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
}

/*
@@ -2078,6 +2124,8 @@ static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
if (!xprt_bound(xprt))
goto out;

+ xs_set_memalloc(xprt);
+
/* Tell the socket layer to start connecting... */
xprt->stat.connect_count++;
xprt->stat.connect_start = jiffies;
@@ -2108,11 +2156,15 @@ static void xs_tcp_setup_socket(struct work_struct *work)
container_of(work, struct sock_xprt, connect_worker.work);
struct socket *sock = transport->sock;
struct rpc_xprt *xprt = &transport->xprt;
+ unsigned long pflags = current->flags;
int status = -EIO;

if (xprt->shutdown)
goto out;

+ if (xprt->swapper)
+ current->flags |= PF_MEMALLOC;
+
if (!sock) {
clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
sock = xs_create_sock(xprt, transport,
@@ -2174,6 +2226,7 @@ out_eagain:
out:
xprt_clear_connecting(xprt);
xprt_wake_pending_tasks(xprt, status);
+ tsk_restore_flags(current, pflags, PF_MEMALLOC);
}

/**
--
1.7.3.4


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