From 70d3ae5c80758cb2bf3cf1e0d5b2c89d040de90b Mon Sep 17 00:00:00 2001
From: Asias He <asias@redhat.com>
Date: Mon, 25 Feb 2013 14:03:42 +0800
Subject: [PATCH] target/file: Add WRITE_SAME w/ UNMAP=1 emulation support

This patch adds support for emulation of WRITE_SAME w/ UNMAP=1 within
fd_execute_write_same_unmap() backend code.

If the FILEIO backend is normal file, the emulation uses fallocate to
punch hole to reclaim the free space used by the file. If the FILEIO
backend is block device, the emulation uses blkdev_issue_discard().

Tested with 512, 1k, 2k, and 4k block_sizes.

Changes in v2:
- Set the various dev->dev_attrib.*unmap* values (nab)

Cc: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
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