[PATCH 07/11] afs: Fix where page->private is set during write

[David Howells]

In afs, page->private is set to indicate the dirty region of a page.  This
is done in afs_write_begin(), but that can't take account of whether the
copy into the page actually worked.

Fix this by moving the change of page->private into afs_write_end().

Fixes: 4343d00872e1 ("afs: Get rid of the afs_writeback record")
Signed-off-by: David Howells <dhowe...@redhat.com>
---

 fs/afs/write.c |   41 ++++++++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/fs/afs/write.c b/fs/afs/write.c
index 6eb367d04eda..9b66e4a6be92 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -135,23 +135,8 @@ int afs_write_begin(struct file *file, struct 
address_space *mapping,
                if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
                    (to < f || from > t))
                        goto flush_conflicting_write;
-               if (from < f)
-                       f = from;
-               if (to > t)
-                       t = to;
-       } else {
-               f = from;
-               t = to;
        }
 
-       priv = (unsigned long)t << AFS_PRIV_SHIFT;
-       priv |= f;
-       trace_afs_page_dirty(vnode, tracepoint_string("begin"),
-                            page->index, priv);
-       if (PagePrivate(page))
-               set_page_private(page, priv);
-       else
-               attach_page_private(page, (void *)priv);
        *_page = page;
        _leave(" = 0");
        return 0;
@@ -185,6 +170,9 @@ int afs_write_end(struct file *file, struct address_space 
*mapping,
 {
        struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
        struct key *key = afs_file_key(file);
+       unsigned long priv;
+       unsigned int f, from = pos & (PAGE_SIZE - 1);
+       unsigned int t, to = from + copied;
        loff_t i_size, maybe_i_size;
        int ret;
 
@@ -216,6 +204,29 @@ int afs_write_end(struct file *file, struct address_space 
*mapping,
                SetPageUptodate(page);
        }
 
+       if (PagePrivate(page)) {
+               priv = page_private(page);
+               f = priv & AFS_PRIV_MAX;
+               t = priv >> AFS_PRIV_SHIFT;
+               if (from < f)
+                       f = from;
+               if (to > t)
+                       t = to;
+               priv = (unsigned long)t << AFS_PRIV_SHIFT;
+               priv |= f;
+               set_page_private(page, priv);
+               trace_afs_page_dirty(vnode, tracepoint_string("dirty+"),
+                                    page->index, priv);
+       } else {
+               f = from;
+               t = to;
+               priv = (unsigned long)t << AFS_PRIV_SHIFT;
+               priv |= f;
+               attach_page_private(page, (void *)priv);
+               trace_afs_page_dirty(vnode, tracepoint_string("dirty"),
+                                    page->index, priv);
+       }
+
        set_page_dirty(page);
        if (PageDirty(page))
                _debug("dirtied");