1 files changed, 23 insertions, 2 deletions

diff --git a/fs/super.c b/fs/super.c
index 09008dbd264e..4798350b2bc9 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -37,7 +37,9 @@
 #include <linux/idr.h>
 #include <linux/kobject.h>
 #include <linux/mutex.h>
+#include <linux/file.h>
 #include <asm/uaccess.h>
+#include "internal.h"
 
 
 LIST_HEAD(super_blocks);
@@ -567,10 +569,29 @@ static 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) {
-                if (S_ISREG(f->f_path.dentry->d_inode->i_mode) && file_count(f))
-                        f->f_mode &= ~FMODE_WRITE;
+                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();
 }