afs: Implement shared-writeable mmap
Implement shared-writeable mmap for AFS.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 4c13137..6807277 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -749,21 +749,45 @@ int afs_flush(struct file *file, fl_owner_t id)
* notification that a previously read-only page is about to become writable
* - if it returns an error, the caller will deliver a bus error signal
*/
-int afs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+int afs_page_mkwrite(struct vm_fault *vmf)
{
- struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host);
+ struct file *file = vmf->vma->vm_file;
+ struct inode *inode = file_inode(file);
+ struct afs_vnode *vnode = AFS_FS_I(inode);
+ unsigned long priv;
_enter("{{%x:%u}},{%lx}",
- vnode->fid.vid, vnode->fid.vnode, page->index);
+ vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
- /* wait for the page to be written to the cache before we allow it to
- * be modified */
+ sb_start_pagefault(inode->i_sb);
+
+ /* Wait for the page to be written to the cache before we allow it to
+ * be modified. We then assume the entire page will need writing back.
+ */
#ifdef CONFIG_AFS_FSCACHE
- fscache_wait_on_page_write(vnode->cache, page);
+ fscache_wait_on_page_write(vnode->cache, vmf->page);
#endif
- _leave(" = 0");
- return 0;
+ if (PageWriteback(vmf->page) &&
+ wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
+ return VM_FAULT_RETRY;
+
+ if (lock_page_killable(vmf->page) < 0)
+ return VM_FAULT_RETRY;
+
+ /* We mustn't change page->private until writeback is complete as that
+ * details the portion of the page we need to write back and we might
+ * need to redirty the page if there's a problem.
+ */
+ wait_on_page_writeback(vmf->page);
+
+ priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
+ priv |= 0; /* From */
+ SetPagePrivate(vmf->page);
+ set_page_private(vmf->page, priv);
+
+ sb_end_pagefault(inode->i_sb);
+ return VM_FAULT_LOCKED;
}
/*
