1 files changed, 59 insertions, 2 deletions

diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c
index 86c0ac87b8e3..3e5f3a6be90a 100644
--- a/fs/exofs/inode.c
+++ b/fs/exofs/inode.c
@@ -63,6 +63,7 @@ struct page_collect {
         bool read_4_write; /* This means two things: that the read is sync
                             * And the pages should not be unlocked.
                             */
+        struct page *that_locked_page;
 };
 
 static void _pcol_init(struct page_collect *pcol, unsigned expected_pages,
@@ -81,6 +82,7 @@ static void _pcol_init(struct page_collect *pcol, unsigned expected_pages,
         pcol->length = 0;
         pcol->pg_first = -1;
         pcol->read_4_write = false;
+        pcol->that_locked_page = NULL;
 }
 
 static void _pcol_reset(struct page_collect *pcol)
@@ -93,6 +95,7 @@ static void _pcol_reset(struct page_collect *pcol)
         pcol->length = 0;
         pcol->pg_first = -1;
         pcol->ios = NULL;
+        pcol->that_locked_page = NULL;
 
         /* this is probably the end of the loop but in writes
          * it might not end here. don't be left with nothing
@@ -391,6 +394,8 @@ static int readpage_strip(void *data, struct page *page)
                 EXOFS_ERR("PageUptodate(0x%lx, 0x%lx)\n", pcol->inode->i_ino,
                           page->index);
 
+        pcol->that_locked_page = page;
+
         if (page->index < end_index)
                 len = PAGE_CACHE_SIZE;
         else if (page->index == end_index)
@@ -560,6 +565,56 @@ static void writepages_done(struct ore_io_state *ios, void *p)
         EXOFS_DBGMSG2("writepages_done END\n");
 }
 
+static struct page *__r4w_get_page(void *priv, u64 offset, bool *uptodate)
+{
+        struct page_collect *pcol = priv;
+        pgoff_t index = offset / PAGE_SIZE;
+
+        if (!pcol->that_locked_page ||
+            (pcol->that_locked_page->index != index)) {
+                struct page *page = find_get_page(pcol->inode->i_mapping, index);
+
+                if (!page) {
+                        page = find_or_create_page(pcol->inode->i_mapping,
+                                                   index, GFP_NOFS);
+                        if (unlikely(!page)) {
+                                EXOFS_DBGMSG("grab_cache_page Failed "
+                                        "index=0x%llx\n", _LLU(index));
+                                return NULL;
+                        }
+                        unlock_page(page);
+                }
+                if (PageDirty(page) || PageWriteback(page))
+                        *uptodate = true;
+                else
+                        *uptodate = PageUptodate(page);
+                EXOFS_DBGMSG("index=0x%lx uptodate=%d\n", index, *uptodate);
+                return page;
+        } else {
+                EXOFS_DBGMSG("YES that_locked_page index=0x%lx\n",
+                             pcol->that_locked_page->index);
+                *uptodate = true;
+                return pcol->that_locked_page;
+        }
+}
+
+static void __r4w_put_page(void *priv, struct page *page)
+{
+        struct page_collect *pcol = priv;
+
+        if (pcol->that_locked_page != page) {
+                EXOFS_DBGMSG("index=0x%lx\n", page->index);
+                page_cache_release(page);
+                return;
+        }
+        EXOFS_DBGMSG("that_locked_page index=0x%lx\n", page->index);
+}
+
+static const struct _ore_r4w_op _r4w_op = {
+        .get_page = &__r4w_get_page,
+        .put_page = &__r4w_put_page,
+};
+
 static int write_exec(struct page_collect *pcol)
 {
         struct exofs_i_info *oi = exofs_i(pcol->inode);
@@ -589,6 +644,7 @@ static int write_exec(struct page_collect *pcol)
         ios = pcol->ios;
         ios->pages = pcol_copy->pages;
         ios->done = writepages_done;
+        ios->r4w = &_r4w_op;
         ios->private = pcol_copy;
 
         /* pages ownership was passed to pcol_copy */
@@ -773,6 +829,7 @@ static int exofs_writepages(struct address_space *mapping,
         return 0;
 }
 
+/*
 static int exofs_writepage(struct page *page, struct writeback_control *wbc)
 {
         struct page_collect pcol;
@@ -788,7 +845,7 @@ static int exofs_writepage(struct page *page, struct writeback_control *wbc)
 
         return write_exec(&pcol);
 }
-
+*/
 /* i_mutex held using inode->i_size directly */
 static void _write_failed(struct inode *inode, loff_t to)
 {
@@ -894,7 +951,7 @@ static void exofs_invalidatepage(struct page *page, unsigned long offset)
 const struct address_space_operations exofs_aops = {
         .readpage       = exofs_readpage,
         .readpages      = exofs_readpages,
-        .writepage      = exofs_writepage,
+        .writepage      = NULL,
         .writepages     = exofs_writepages,
         .write_begin    = exofs_write_begin_export,
         .write_end      = exofs_write_end,