ext4: wait for writeback to complete while making pages writable

[pandora-kernel.git] / fs / ext4 / inode.c

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f6caaac..6348c1f 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5809,15 +5809,19 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
                goto out_unlock;
        }
        ret = 0;
-       if (PageMappedToDisk(page))
-               goto out_unlock;
+
+       lock_page(page);
+       wait_on_page_writeback(page);
+       if (PageMappedToDisk(page)) {
+               up_read(&inode->i_alloc_sem);
+               return VM_FAULT_LOCKED;
+       }
 
        if (page->index == size >> PAGE_CACHE_SHIFT)
                len = size & ~PAGE_CACHE_MASK;
        else
                len = PAGE_CACHE_SIZE;
 
-       lock_page(page);
        /*
         * return if we have all the buffers mapped. This avoid
         * the need to call write_begin/write_end which does a
@@ -5827,8 +5831,8 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
        if (page_has_buffers(page)) {
                if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL,
                                        ext4_bh_unmapped)) {
-                       unlock_page(page);
-                       goto out_unlock;
+                       up_read(&inode->i_alloc_sem);
+                       return VM_FAULT_LOCKED;
                }
        }
        unlock_page(page);
@@ -5848,6 +5852,16 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
        if (ret < 0)
                goto out_unlock;
        ret = 0;
+
+       /*
+        * write_begin/end might have created a dirty page and someone
+        * could wander in and start the IO.  Make sure that hasn't
+        * happened.
+        */
+       lock_page(page);
+       wait_on_page_writeback(page);
+       up_read(&inode->i_alloc_sem);
+       return VM_FAULT_LOCKED;
 out_unlock:
        if (ret)
                ret = VM_FAULT_SIGBUS;