udf: Fix deadlock in udf_release_file()

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.

CC: stable@vger.kernel.org (2.6.38 & later)
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Reviewed-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 0 insertions, 2 deletions

diff --git a/fs/udf/file.c b/fs/udf/file.c
index dca0c3881e82..d567b8448dfc 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;
 }