udf: Fix race between write(2) and close(2)

[cascardo/linux.git] / fs / udf / file.c

diff --git a/fs/udf/file.c b/fs/udf/file.c
index 86c6743..bb15771 100644 (file)
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -223,11 +223,18 @@ out:
 
 static int udf_release_file(struct inode *inode, struct file *filp)
 {
-       if (filp->f_mode & FMODE_WRITE) {
+       if (filp->f_mode & FMODE_WRITE &&
+           atomic_read(&inode->i_writecount) > 1) {
+               /*
+                * Grab i_mutex to avoid races with writes changing i_size
+                * while we are running.
+                */
+               mutex_lock(&inode->i_mutex);
                down_write(&UDF_I(inode)->i_data_sem);
                udf_discard_prealloc(inode);
                udf_truncate_tail_extent(inode);
                up_write(&UDF_I(inode)->i_data_sem);
+               mutex_unlock(&inode->i_mutex);
        }
        return 0;
 }