udf: Fix deadlock in udf_release_file()

commit a0391a3ae91d301c0e59368531a4de5f0b122bcf 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 <viro@ZenIV.linux.org.uk>
Reviewed-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/udf/file.c b/fs/udf/file.c
index 0c0c9d33dbc7063a72f6f6d016de6a5ed7c0c4d0..3438b0000413af78285419a6a0cb6236788e0220 100644 (file)
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -201,12 +201,10 @@ out:
 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;
 }