From: Jan Kara <jack@suse.cz>
Date: Mon, 20 Feb 2012 16:49:56 +0000 (+0100)
Subject: udf: Fix deadlock in udf_release_file()
X-Git-Tag: firefly_0821_release~7541^2~1466
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=bc9d8a3ba0a4b0c136c78ba5e35906401d7dc5ba;p=firefly-linux-kernel-4.4.55.git

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 0c0c9d33dbc7..3438b0000413 100644
--- 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;
 }