linux-kernel - [ 086/108] udf: Fix deadlock in udf_release

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Message-Id: <20120330195734.491949938@linuxfoundation.org>
Date:	Fri, 30 Mar 2012 12:58:48 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Al Viro <viro@...IV.linux.org.uk>,
	Namjae Jeon <linkinjeon@...il.com>, Jan Kara <jack@...e.cz>
Subject: [ 086/108] udf: Fix deadlock in udf_release_file()

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@...e.cz>

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@...IV.linux.org.uk>
Reviewed-by: Namjae Jeon <linkinjeon@...il.com>
Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/udf/file.c |    2 --
 1 file changed, 2 deletions(-)

--- 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;
 }


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