8 files changed, 153 insertions, 75 deletions

diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index 195c1ea6151a..db7ad719628a 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -86,6 +86,14 @@ 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_V4 && EXPERIMENTAL
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index b7b4f80968b5..1ba385b7c90d 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -115,17 +115,28 @@ 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_release_pages(struct page **pages, unsigned int npages)
@@ -303,7 +314,7 @@ static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
  */
 static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *desc,
                                                 const struct iovec *iov,
-                                                loff_t pos)
+                                                loff_t pos, bool uio)
 {
         struct nfs_direct_req *dreq = desc->pg_dreq;
         struct nfs_open_context *ctx = dreq->ctx;
@@ -331,12 +342,20 @@ static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *de
                                           GFP_KERNEL);
                 if (!pagevec)
                         break;
-                down_read(&current->mm->mmap_sem);
-                result = get_user_pages(current, current->mm, user_addr,
+                if (uio) {
+                        down_read(&current->mm->mmap_sem);
+                        result = get_user_pages(current, current->mm, user_addr,
                                         npages, 1, 0, pagevec, NULL);
-                up_read(&current->mm->mmap_sem);
-                if (result < 0)
-                        break;
+                        up_read(&current->mm->mmap_sem);
+                        if (result < 0)
+                                break;
+                } else {
+                        WARN_ON(npages != 1);
+                        result = get_kernel_page(user_addr, 1, pagevec);
+                        if (WARN_ON(result != 1))
+                                break;
+                }
+
                 if ((unsigned)result < npages) {
                         bytes = result * PAGE_SIZE;
                         if (bytes <= pgbase) {
@@ -386,7 +405,7 @@ static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *de
 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)
 {
         struct nfs_pageio_descriptor desc;
         ssize_t result = -EINVAL;
@@ -400,7 +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(&desc, vec, pos);
+                result = nfs_direct_read_schedule_segment(&desc, vec, pos, uio);
                 if (result < 0)
                         break;
                 requested_bytes += result;
@@ -426,7 +445,7 @@ 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;
@@ -444,7 +463,7 @@ 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);
         NFS_I(inode)->read_io += result;
@@ -610,7 +629,7 @@ static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode
  */
 static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *desc,
                                                  const struct iovec *iov,
-                                                 loff_t pos)
+                                                 loff_t pos, bool uio)
 {
         struct nfs_direct_req *dreq = desc->pg_dreq;
         struct nfs_open_context *ctx = dreq->ctx;
@@ -638,12 +657,19 @@ static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *d
                 if (!pagevec)
                         break;
 
-                down_read(&current->mm->mmap_sem);
-                result = get_user_pages(current, current->mm, user_addr,
-                                        npages, 0, 0, pagevec, NULL);
-                up_read(&current->mm->mmap_sem);
-                if (result < 0)
-                        break;
+                if (uio) {
+                        down_read(&current->mm->mmap_sem);
+                        result = get_user_pages(current, current->mm, user_addr,
+                                                npages, 0, 0, pagevec, NULL);
+                        up_read(&current->mm->mmap_sem);
+                        if (result < 0)
+                                break;
+                } else {
+                        WARN_ON(npages != 1);
+                        result = get_kernel_page(user_addr, 0, pagevec);
+                        if (WARN_ON(result != 1))
+                                break;
+                }
 
                 if ((unsigned)result < npages) {
                         bytes = result * PAGE_SIZE;
@@ -774,7 +800,7 @@ static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
                                                const struct iovec *iov,
                                                unsigned long nr_segs,
-                                               loff_t pos)
+                                               loff_t pos, bool uio)
 {
         struct nfs_pageio_descriptor desc;
         struct inode *inode = dreq->inode;
@@ -790,7 +816,7 @@ 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(&desc, vec, pos);
+                result = nfs_direct_write_schedule_segment(&desc, vec, pos, uio);
                 if (result < 0)
                         break;
                 requested_bytes += result;
@@ -818,7 +844,7 @@ 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;
@@ -836,7 +862,7 @@ 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);
+        result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, uio);
         if (!result)
                 result = nfs_direct_wait(dreq);
 out_release:
@@ -867,7 +893,7 @@ 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;
@@ -892,7 +918,7 @@ 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;
 
@@ -923,7 +949,7 @@ 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;
@@ -955,7 +981,7 @@ 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) {
                 struct inode *inode = mapping->host;
 
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index b039a17ee941..75d6d0a3d32e 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -180,7 +180,7 @@ 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,
@@ -439,7 +439,7 @@ static void nfs_invalidate_page(struct page *page, unsigned long offset)
         if (offset != 0)
                 return;
         /* Cancel any unstarted writes on this page */
-        nfs_wb_page_cancel(page->mapping->host, page);
+        nfs_wb_page_cancel(page_file_mapping(page)->host, page);
 
         nfs_fscache_invalidate_page(page, page->mapping->host);
 }
@@ -484,7 +484,7 @@ static int nfs_release_page(struct page *page, gfp_t gfp)
  */
 static int nfs_launder_page(struct page *page)
 {
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = page_file_mapping(page)->host;
         struct nfs_inode *nfsi = NFS_I(inode);
 
         dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
@@ -494,6 +494,20 @@ 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,
@@ -508,6 +522,10 @@ 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
 };
 
 /*
@@ -533,7 +551,7 @@ static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
         nfs_fscache_wait_on_page_write(NFS_I(dentry->d_inode), page);
 
         lock_page(page);
-        mapping = page->mapping;
+        mapping = page_file_mapping(page);
         if (mapping != dentry->d_inode->i_mapping)
                 goto out_unlock;
 
@@ -582,7 +600,7 @@ 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/fs/nfs/inode.c b/fs/nfs/inode.c
index 2ed6138f32ad..c6e895f0fbf3 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -897,6 +897,10 @@ int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
         struct nfs_inode *nfsi = NFS_I(inode);
         int ret = 0;
 
+        /* swapfiles are not supposed to be shared. */
+        if (IS_SWAPFILE(inode))
+                goto out;
+
         if (nfs_mapping_need_revalidate_inode(inode)) {
                 ret = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
                 if (ret < 0)
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 8865538b26b6..31fdb03225cd 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -554,13 +554,14 @@ void nfs_super_set_maxbytes(struct super_block *sb, __u64 maxfilesize)
 static inline
 unsigned int nfs_page_length(struct page *page)
 {
-        loff_t i_size = i_size_read(page->mapping->host);
+        loff_t i_size = i_size_read(page_file_mapping(page)->host);
 
         if (i_size > 0) {
+                pgoff_t page_index = page_file_index(page);
                 pgoff_t end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
-                if (page->index < end_index)
+                if (page_index < end_index)
                         return PAGE_CACHE_SIZE;
-                if (page->index == end_index)
+                if (page_index == end_index)
                         return ((i_size - 1) & ~PAGE_CACHE_MASK) + 1;
         }
         return 0;
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 1e7d8879dae6..1a6732ed04a4 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -71,7 +71,7 @@ void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
 static inline struct nfs_page *
 nfs_page_alloc(void)
 {
-        struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_KERNEL);
+        struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
         if (p)
                 INIT_LIST_HEAD(&p->wb_list);
         return p;
@@ -118,7 +118,7 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
          * long write-back delay. This will be adjusted in
          * update_nfs_request below if the region is not locked. */
         req->wb_page    = page;
-        req->wb_index   = page->index;
+        req->wb_index   = page_file_index(page);
         page_cache_get(page);
         req->wb_offset  = offset;
         req->wb_pgbase  = offset;
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 6935e401ad76..b6bdb18e892c 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -527,11 +527,11 @@ static const struct rpc_call_ops nfs_read_common_ops = {
 int nfs_readpage(struct file *file, struct page *page)
 {
         struct nfs_open_context *ctx;
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = page_file_mapping(page)->host;
         int             error;
 
         dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
-                page, PAGE_CACHE_SIZE, page->index);
+                page, PAGE_CACHE_SIZE, page_file_index(page));
         nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
         nfs_add_stats(inode, NFSIOS_READPAGES, 1);
 
@@ -585,7 +585,7 @@ static int
 readpage_async_filler(void *data, struct page *page)
 {
         struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = page_file_mapping(page)->host;
         struct nfs_page *new;
         unsigned int len;
         int error;
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index e4a2ad2059bd..5829d0ce7cfb 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -52,7 +52,7 @@ static mempool_t *nfs_commit_mempool;
 
 struct nfs_commit_data *nfs_commitdata_alloc(void)
 {
-        struct nfs_commit_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOFS);
+        struct nfs_commit_data *p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
 
         if (p) {
                 memset(p, 0, sizeof(*p));
@@ -70,7 +70,7 @@ EXPORT_SYMBOL_GPL(nfs_commit_free);
 
 struct nfs_write_header *nfs_writehdr_alloc(void)
 {
-        struct nfs_write_header *p = mempool_alloc(nfs_wdata_mempool, GFP_NOFS);
+        struct nfs_write_header *p = mempool_alloc(nfs_wdata_mempool, GFP_NOIO);
 
         if (p) {
                 struct nfs_pgio_header *hdr = &p->header;
@@ -142,25 +142,38 @@ static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 }
 
-static struct nfs_page *nfs_page_find_request_locked(struct page *page)
+static struct nfs_page *
+nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page)
 {
         struct nfs_page *req = NULL;
 
-        if (PagePrivate(page)) {
+        if (PagePrivate(page))
                 req = (struct nfs_page *)page_private(page);
-                if (req != NULL)
-                        kref_get(&req->wb_kref);
+        else if (unlikely(PageSwapCache(page))) {
+                struct nfs_page *freq, *t;
+
+                /* Linearly search the commit list for the correct req */
+                list_for_each_entry_safe(freq, t, &nfsi->commit_info.list, wb_list) {
+                        if (freq->wb_page == page) {
+                                req = freq;
+                                break;
+                        }
+                }
         }
+
+        if (req)
+                kref_get(&req->wb_kref);
+
         return req;
 }
 
 static struct nfs_page *nfs_page_find_request(struct page *page)
 {
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = page_file_mapping(page)->host;
         struct nfs_page *req = NULL;
 
         spin_lock(&inode->i_lock);
-        req = nfs_page_find_request_locked(page);
+        req = nfs_page_find_request_locked(NFS_I(inode), page);
         spin_unlock(&inode->i_lock);
         return req;
 }
@@ -168,16 +181,16 @@ static struct nfs_page *nfs_page_find_request(struct page *page)
 /* Adjust the file length if we're writing beyond the end */
 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 {
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = page_file_mapping(page)->host;
         loff_t end, i_size;
         pgoff_t end_index;
 
         spin_lock(&inode->i_lock);
         i_size = i_size_read(inode);
         end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
-        if (i_size > 0 && page->index < end_index)
+        if (i_size > 0 && page_file_index(page) < end_index)
                 goto out;
-        end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
+        end = page_file_offset(page) + ((loff_t)offset+count);
         if (i_size >= end)
                 goto out;
         i_size_write(inode, end);
@@ -190,7 +203,7 @@ out:
 static void nfs_set_pageerror(struct page *page)
 {
         SetPageError(page);
-        nfs_zap_mapping(page->mapping->host, page->mapping);
+        nfs_zap_mapping(page_file_mapping(page)->host, page_file_mapping(page));
 }
 
 /* We can set the PG_uptodate flag if we see that a write request
@@ -231,7 +244,7 @@ static int nfs_set_page_writeback(struct page *page)
         int ret = test_set_page_writeback(page);
 
         if (!ret) {
-                struct inode *inode = page->mapping->host;
+                struct inode *inode = page_file_mapping(page)->host;
                 struct nfs_server *nfss = NFS_SERVER(inode);
 
                 if (atomic_long_inc_return(&nfss->writeback) >
@@ -245,7 +258,7 @@ static int nfs_set_page_writeback(struct page *page)
 
 static void nfs_end_page_writeback(struct page *page)
 {
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = page_file_mapping(page)->host;
         struct nfs_server *nfss = NFS_SERVER(inode);
 
         end_page_writeback(page);
@@ -255,13 +268,13 @@ static void nfs_end_page_writeback(struct page *page)
 
 static struct nfs_page *nfs_find_and_lock_request(struct page *page, bool nonblock)
 {
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = page_file_mapping(page)->host;
         struct nfs_page *req;
         int ret;
 
         spin_lock(&inode->i_lock);
         for (;;) {
-                req = nfs_page_find_request_locked(page);
+                req = nfs_page_find_request_locked(NFS_I(inode), page);
                 if (req == NULL)
                         break;
                 if (nfs_lock_request(req))
@@ -316,13 +329,13 @@ out:
 
 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc, struct nfs_pageio_descriptor *pgio)
 {
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = page_file_mapping(page)->host;
         int ret;
 
         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 
-        nfs_pageio_cond_complete(pgio, page->index);
+        nfs_pageio_cond_complete(pgio, page_file_index(page));
         ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE);
         if (ret == -EAGAIN) {
                 redirty_page_for_writepage(wbc, page);
@@ -339,7 +352,7 @@ static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc
         struct nfs_pageio_descriptor pgio;
         int err;
 
-        NFS_PROTO(page->mapping->host)->write_pageio_init(&pgio,
+        NFS_PROTO(page_file_mapping(page)->host)->write_pageio_init(&pgio,
                                                           page->mapping->host,
                                                           wb_priority(wbc),
                                                           &nfs_async_write_completion_ops);
@@ -416,9 +429,15 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
         spin_lock(&inode->i_lock);
         if (!nfsi->npages && NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
                 inode->i_version++;
-        set_bit(PG_MAPPED, &req->wb_flags);
-        SetPagePrivate(req->wb_page);
-        set_page_private(req->wb_page, (unsigned long)req);
+        /*
+         * Swap-space should not get truncated. Hence no need to plug the race
+         * with invalidate/truncate.
+         */
+        if (likely(!PageSwapCache(req->wb_page))) {
+                set_bit(PG_MAPPED, &req->wb_flags);
+                SetPagePrivate(req->wb_page);
+                set_page_private(req->wb_page, (unsigned long)req);
+        }
         nfsi->npages++;
         kref_get(&req->wb_kref);
         spin_unlock(&inode->i_lock);
@@ -435,9 +454,11 @@ static void nfs_inode_remove_request(struct nfs_page *req)
         BUG_ON (!NFS_WBACK_BUSY(req));
 
         spin_lock(&inode->i_lock);
-        set_page_private(req->wb_page, 0);
-        ClearPagePrivate(req->wb_page);
-        clear_bit(PG_MAPPED, &req->wb_flags);
+        if (likely(!PageSwapCache(req->wb_page))) {
+                set_page_private(req->wb_page, 0);
+                ClearPagePrivate(req->wb_page);
+                clear_bit(PG_MAPPED, &req->wb_flags);
+        }
         nfsi->npages--;
         spin_unlock(&inode->i_lock);
         nfs_release_request(req);
@@ -474,7 +495,7 @@ nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
         spin_unlock(cinfo->lock);
         if (!cinfo->dreq) {
                 inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
-                inc_bdi_stat(req->wb_page->mapping->backing_dev_info,
+                inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
                              BDI_RECLAIMABLE);
                 __mark_inode_dirty(req->wb_context->dentry->d_inode,
                                    I_DIRTY_DATASYNC);
@@ -541,7 +562,7 @@ static void
 nfs_clear_page_commit(struct page *page)
 {
         dec_zone_page_state(page, NR_UNSTABLE_NFS);
-        dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
+        dec_bdi_stat(page_file_mapping(page)->backing_dev_info, BDI_RECLAIMABLE);
 }
 
 static void
@@ -733,7 +754,7 @@ static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
         spin_lock(&inode->i_lock);
 
         for (;;) {
-                req = nfs_page_find_request_locked(page);
+                req = nfs_page_find_request_locked(NFS_I(inode), page);
                 if (req == NULL)
                         goto out_unlock;
 
@@ -792,7 +813,7 @@ out_err:
 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
                 struct page *page, unsigned int offset, unsigned int bytes)
 {
-        struct inode *inode = page->mapping->host;
+        struct inode *inode = page_file_mapping(page)->host;
         struct nfs_page *req;
 
         req = nfs_try_to_update_request(inode, page, offset, bytes);
@@ -845,7 +866,7 @@ int nfs_flush_incompatible(struct file *file, struct page *page)
                 nfs_release_request(req);
                 if (!do_flush)
                         return 0;
-                status = nfs_wb_page(page->mapping->host, page);
+                status = nfs_wb_page(page_file_mapping(page)->host, page);
         } while (status == 0);
         return status;
 }
@@ -875,7 +896,7 @@ int nfs_updatepage(struct file *file, struct page *page,
                 unsigned int offset, unsigned int count)
 {
         struct nfs_open_context *ctx = nfs_file_open_context(file);
-        struct inode    *inode = page->mapping->host;
+        struct inode    *inode = page_file_mapping(page)->host;
         int             status = 0;
 
         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
@@ -883,7 +904,7 @@ int nfs_updatepage(struct file *file, struct page *page,
         dprintk("NFS:       nfs_updatepage(%s/%s %d@%lld)\n",
                 file->f_path.dentry->d_parent->d_name.name,
                 file->f_path.dentry->d_name.name, count,
-                (long long)(page_offset(page) + offset));
+                (long long)(page_file_offset(page) + offset));
 
         /* If we're not using byte range locks, and we know the page
          * is up to date, it may be more efficient to extend the write
@@ -1474,7 +1495,7 @@ void nfs_retry_commit(struct list_head *page_list,
                 nfs_mark_request_commit(req, lseg, cinfo);
                 if (!cinfo->dreq) {
                         dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
-                        dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
+                        dec_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
                                      BDI_RECLAIMABLE);
                 }
                 nfs_unlock_and_release_request(req);
@@ -1731,7 +1752,7 @@ int nfs_wb_page_cancel(struct inode *inode, struct page *page)
  */
 int nfs_wb_page(struct inode *inode, struct page *page)
 {
-        loff_t range_start = page_offset(page);
+        loff_t range_start = page_file_offset(page);
         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
         struct writeback_control wbc = {
                 .sync_mode = WB_SYNC_ALL,