The WRITE SAME to TRIM translation rewrites the DATA OUT buffer.  While
the SCSI code accomodates for this by passing a read-writable buffer
userspace applications don't cater for this behavior.  In fact it can
be used to rewrite e.g. a readonly file through mmap and should be
considered as a security fix.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NTejun Heo <tj@kernel.org>