4 files changed, 28 insertions, 9 deletions

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 790ef6fbe495..28bfea75bcf2 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -171,6 +171,7 @@ prototypes:
         int (*releasepage) (struct page *, int);
         int (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
                         loff_t offset, unsigned long nr_segs);
+        int (*launder_page) (struct page *);
 
 locking rules:
         All except set_page_dirty may block
@@ -188,6 +189,7 @@ bmap:			yes
 invalidatepage:         no      yes
 releasepage:            no      yes
 direct_IO:              no
+launder_page:           no      yes
 
         ->prepare_write(), ->commit_write(), ->sync_page() and ->readpage()
 may be called from the request handler (/dev/loop).
@@ -281,6 +283,12 @@ buffers from the page in preparation for freeing it.  It returns zero to
 indicate that the buffers are (or may be) freeable.  If ->releasepage is zero,
 the kernel assumes that the fs has no private interest in the buffers.
 
+        ->launder_page() may be called prior to releasing a page if
+it is still found to be dirty. It returns zero if the page was successfully
+cleaned, or an error value if not. Note that in order to prevent the page
+getting mapped back in and redirtied, it needs to be kept locked
+across the entire operation.
+
         Note: currently almost all instances of address_space methods are
 using BKL for internal serialization and that's one of the worst sources
 of contention. Normally they are calling library functions (in fs/buffer.c)
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 0dd6be346aa7..fab20d06d936 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -315,14 +315,13 @@ static void nfs_invalidate_page(struct page *page, unsigned long offset)
 
 static int nfs_release_page(struct page *page, gfp_t gfp)
 {
-        /*
-         * Avoid deadlock on nfs_wait_on_request().
-         */
-        if (!(gfp & __GFP_FS))
-                return 0;
-        /* Hack... Force nfs_wb_page() to write out the page */
-        SetPageDirty(page);
-        return !nfs_wb_page(page->mapping->host, page);
+        /* If PagePrivate() is set, then the page is not freeable */
+        return 0;
+}
+
+static int nfs_launder_page(struct page *page)
+{
+        return nfs_wb_page(page->mapping->host, page);
 }
 
 const struct address_space_operations nfs_file_aops = {
@@ -338,6 +337,7 @@ const struct address_space_operations nfs_file_aops = {
 #ifdef CONFIG_NFS_DIRECTIO
         .direct_IO = nfs_direct_IO,
 #endif
+        .launder_page = nfs_launder_page,
 };
 
 static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 186da813541e..14a337cc3464 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -426,6 +426,7 @@ struct address_space_operations {
         /* migrate the contents of a page to the specified target */
         int (*migratepage) (struct address_space *,
                         struct page *, struct page *);
+        int (*launder_page) (struct page *);
 };
 
 struct backing_dev_info;
diff --git a/mm/truncate.c b/mm/truncate.c
index ecdfdcc50522..6c79ca4a1ca7 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -341,6 +341,15 @@ failed:
         return 0;
 }
 
+static int do_launder_page(struct address_space *mapping, struct page *page)
+{
+        if (!PageDirty(page))
+                return 0;
+        if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
+                return 0;
+        return mapping->a_ops->launder_page(page);
+}
+
 /**
  * invalidate_inode_pages2_range - remove range of pages from an address_space
  * @mapping: the address_space
@@ -405,7 +414,8 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
                                           PAGE_CACHE_SIZE, 0);
                                 }
                         }
-                        if (!invalidate_complete_page2(mapping, page))
+                        ret = do_launder_page(mapping, page);
+                        if (ret == 0 && !invalidate_complete_page2(mapping, page))
                                 ret = -EIO;
                         unlock_page(page);
                 }