1 files changed, 30 insertions, 0 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 6b4a79f4ad1d..94e94bd11aae 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -495,6 +495,35 @@ static int nfs_release_page(struct page *page, gfp_t gfp)
         return nfs_fscache_release_page(page, gfp);
 }
 
+static void nfs_check_dirty_writeback(struct page *page,
+                                bool *dirty, bool *writeback)
+{
+        struct nfs_inode *nfsi;
+        struct address_space *mapping = page_file_mapping(page);
+
+        if (!mapping || PageSwapCache(page))
+                return;
+
+        /*
+         * Check if an unstable page is currently being committed and
+         * if so, have the VM treat it as if the page is under writeback
+         * so it will not block due to pages that will shortly be freeable.
+         */
+        nfsi = NFS_I(mapping->host);
+        if (test_bit(NFS_INO_COMMIT, &nfsi->flags)) {
+                *writeback = true;
+                return;
+        }
+
+        /*
+         * If PagePrivate() is set, then the page is not freeable and as the
+         * inode is not being committed, it's not going to be cleaned in the
+         * near future so treat it as dirty
+         */
+        if (PagePrivate(page))
+                *dirty = true;
+}
+
 /*
  * Attempt to clear the private state associated with a page when an error
  * occurs that requires the cached contents of an inode to be written back or
@@ -542,6 +571,7 @@ const struct address_space_operations nfs_file_aops = {
         .direct_IO = nfs_direct_IO,
         .migratepage = nfs_migrate_page,
         .launder_page = nfs_launder_page,
+        .is_dirty_writeback = nfs_check_dirty_writeback,
         .error_remove_page = generic_error_remove_page,
 #ifdef CONFIG_NFS_SWAP
         .swap_activate = nfs_swap_activate,