1 files changed, 15 insertions, 6 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index a3a3eecef689..6cc77dc3f3ff 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -297,16 +297,20 @@ static int proc_fd_link(struct inode *inode, struct dentry **dentry, struct vfsm
 
         files = get_files_struct(task);
         if (files) {
-                rcu_read_lock();
+                /*
+                 * We are not taking a ref to the file structure, so we must
+                 * hold ->file_lock.
+                 */
+                spin_lock(&files->file_lock);
                 file = fcheck_files(files, fd);
                 if (file) {
                         *mnt = mntget(file->f_vfsmnt);
                         *dentry = dget(file->f_dentry);
-                        rcu_read_unlock();
+                        spin_unlock(&files->file_lock);
                         put_files_struct(files);
                         return 0;
                 }
-                rcu_read_unlock();
+                spin_unlock(&files->file_lock);
                 put_files_struct(files);
         }
         return -ENOENT;
@@ -1523,7 +1527,12 @@ static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry,
         if (!files)
                 goto out_unlock;
         inode->i_mode = S_IFLNK;
-        rcu_read_lock();
+
+        /*
+         * We are not taking a ref to the file structure, so we must
+         * hold ->file_lock.
+         */
+        spin_lock(&files->file_lock);
         file = fcheck_files(files, fd);
         if (!file)
                 goto out_unlock2;
@@ -1531,7 +1540,7 @@ static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry,
                 inode->i_mode |= S_IRUSR | S_IXUSR;
         if (file->f_mode & 2)
                 inode->i_mode |= S_IWUSR | S_IXUSR;
-        rcu_read_unlock();
+        spin_unlock(&files->file_lock);
         put_files_struct(files);
         inode->i_op = &proc_pid_link_inode_operations;
         inode->i_size = 64;
@@ -1541,7 +1550,7 @@ static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry,
         return NULL;
 
 out_unlock2:
-        rcu_read_unlock();
+        spin_unlock(&files->file_lock);
         put_files_struct(files);
 out_unlock:
         iput(inode);