1 files changed, 39 insertions, 1 deletions

diff --git a/fs/file_table.c b/fs/file_table.c
index 54018fe48840..334ce39881f8 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -214,7 +214,7 @@ int init_file(struct file *file, struct vfsmount *mnt, struct dentry *dentry,
          */
         if ((mode & FMODE_WRITE) && !special_file(dentry->d_inode->i_mode)) {
                 file_take_write(file);
-                error = mnt_want_write(mnt);
+                error = mnt_clone_write(mnt);
                 WARN_ON(error);
         }
         return error;
@@ -399,6 +399,44 @@ too_bad:
         return 0;
 }
 
+/**
+ *      mark_files_ro - mark all files read-only
+ *      @sb: superblock in question
+ *
+ *      All files are marked read-only.  We don't care about pending
+ *      delete files so this should be used in 'force' mode only.
+ */
+void mark_files_ro(struct super_block *sb)
+{
+        struct file *f;
+
+retry:
+        file_list_lock();
+        list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
+                struct vfsmount *mnt;
+                if (!S_ISREG(f->f_path.dentry->d_inode->i_mode))
+                       continue;
+                if (!file_count(f))
+                        continue;
+                if (!(f->f_mode & FMODE_WRITE))
+                        continue;
+                f->f_mode &= ~FMODE_WRITE;
+                if (file_check_writeable(f) != 0)
+                        continue;
+                file_release_write(f);
+                mnt = mntget(f->f_path.mnt);
+                file_list_unlock();
+                /*
+                 * This can sleep, so we can't hold
+                 * the file_list_lock() spinlock.
+                 */
+                mnt_drop_write(mnt);
+                mntput(mnt);
+                goto retry;
+        }
+        file_list_unlock();
+}
+
 void __init files_init(unsigned long mempages)
 { 
         int n;