[PATCH] r/o bind mounts: elevate write count for open()s

[linux-2.6-omap-h63xx.git] / fs / file_table.c

diff --git a/fs/file_table.c b/fs/file_table.c
index 3f73eb1f195a12638cf00fa276b39cd6eaa9f18e..71efc7000226789e54d7d1dfb7874638ba619f81 100644 (file)
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -199,6 +199,17 @@ int init_file(struct file *file, struct vfsmount *mnt, struct dentry *dentry,
        file->f_mapping = dentry->d_inode->i_mapping;
        file->f_mode = mode;
        file->f_op = fop;
+
+       /*
+        * These mounts don't really matter in practice
+        * for r/o bind mounts.  They aren't userspace-
+        * visible.  We do this for consistency, and so
+        * that we can do debugging checks at __fput()
+        */
+       if ((mode & FMODE_WRITE) && !special_file(dentry->d_inode->i_mode)) {
+               error = mnt_want_write(mnt);
+               WARN_ON(error);
+       }
        return error;
 }
 EXPORT_SYMBOL(init_file);
@@ -221,10 +232,13 @@ EXPORT_SYMBOL(fput);
  */
 void drop_file_write_access(struct file *file)
 {
+       struct vfsmount *mnt = file->f_path.mnt;
        struct dentry *dentry = file->f_path.dentry;
        struct inode *inode = dentry->d_inode;
 
        put_write_access(inode);
+       if (!special_file(inode->i_mode))
+               mnt_drop_write(mnt);
 }
 EXPORT_SYMBOL_GPL(drop_file_write_access);