NFS: Don't discard readdir results

If a readdir call returns more data than we can fit into one page
cache page, then allocate a new one for that data rather than
discarding the data.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 842f69120a01e1d79f7d19e09d850523b24cfb7a..f7248145c333e05089b5af28cdf5e1b715c29d5a 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -320,6 +320,26 @@ static void nfs_readdir_page_set_eof(struct page *page)
        kunmap_atomic(array);
 }
 
+static void nfs_readdir_page_unlock_and_put(struct page *page)
+{
+       unlock_page(page);
+       put_page(page);
+}
+
+static struct page *nfs_readdir_page_get_next(struct address_space *mapping,
+                                             pgoff_t index, u64 cookie)
+{
+       struct page *page;
+
+       page = nfs_readdir_page_get_locked(mapping, index, cookie);
+       if (page) {
+               if (nfs_readdir_page_last_cookie(page) == cookie)
+                       return page;
+               nfs_readdir_page_unlock_and_put(page);
+       }
+       return NULL;
+}
+
 static inline
 int is_32bit_api(void)
 {
@@ -637,13 +657,15 @@ out:
 }
 
 /* Perform conversion from xdr to cache array */
-static
-int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *entry,
-                               struct page **xdr_pages, struct page *page, unsigned int buflen)
+static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
+                                  struct nfs_entry *entry,
+                                  struct page **xdr_pages,
+                                  struct page *fillme, unsigned int buflen)
 {
+       struct address_space *mapping = desc->file->f_mapping;
        struct xdr_stream stream;
        struct xdr_buf buf;
-       struct page *scratch;
+       struct page *scratch, *new, *page = fillme;
        int status;
 
        scratch = alloc_page(GFP_KERNEL);
@@ -666,6 +688,19 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
                                        desc->dir_verifier);
 
                status = nfs_readdir_add_to_array(entry, page);
+               if (status != -ENOSPC)
+                       continue;
+
+               if (page->mapping != mapping)
+                       break;
+               new = nfs_readdir_page_get_next(mapping, page->index + 1,
+                                               entry->prev_cookie);
+               if (!new)
+                       break;
+               if (page != fillme)
+                       nfs_readdir_page_unlock_and_put(page);
+               page = new;
+               status = nfs_readdir_add_to_array(entry, page);
        } while (!status && !entry->eof);
 
        switch (status) {
@@ -681,6 +716,9 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
                break;
        }
 
+       if (page != fillme)
+               nfs_readdir_page_unlock_and_put(page);
+
        put_page(scratch);
        return status;
 }