[ 086/108] udf: Fix deadlock in udf_release_file()

From: Greg KH
Date: Fri Mar 30 2012 - 18:43:15 EST


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

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

From: Jan Kara <jack@xxxxxxx>

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@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Namjae Jeon <linkinjeon@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
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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