2 files changed, 39 insertions, 14 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 35f7e4bc680e..1d57fe9f49a9 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -882,6 +882,10 @@ 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/write.c b/fs/nfs/write.c
index d0feca32b4fe..974e9c2d31fd 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -139,15 +139,28 @@ 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;
 }
 
@@ -157,7 +170,7 @@ static struct nfs_page *nfs_page_find_request(struct page *page)
         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;
 }
@@ -258,7 +271,7 @@ static struct nfs_page *nfs_find_and_lock_request(struct page *page, bool nonblo
 
         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))
@@ -413,9 +426,15 @@ 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);
@@ -432,9 +451,11 @@ 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);
@@ -730,7 +751,7 @@ 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;
 
@@ -1744,7 +1765,7 @@ 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,