udf: Fix deadlock in udf_release_file()

commit a0391a3 upstream. udf_release_file() can be called from munmap() path with mmap_sem held. Thus we cannot take i_mutex there because that ranks above mmap_sem. Luckily, i_mutex is not needed in udf_release_file() anymore since protection by i_data_sem is enough to protect from races with write and truncate. Reported-by: Al Viro <[email protected]> Reviewed-by: Namjae Jeon <[email protected]> Signed-off-by: Jan Kara <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
ar0n · Apr 2, 2012 · 712f04f · 712f04f
1 parent 83e4194
commit 712f04f
Showing 1 changed file with 0 additions and 2 deletions.
diff --git a/fs/udf/file.c b/fs/udf/file.c
@@ -201,12 +201,10 @@ long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 static int udf_release_file(struct inode *inode, struct file *filp)
 {
 	if (filp->f_mode & FMODE_WRITE) {
-		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;
 }