tree afee073ae3aa38326b8f0a4b2e4655cb7b463181
parent c0c2dd499b7ae3d4d314ef2965ee2387848a39d9
author Asias He <asias@redhat.com> 1361772222 +0800
committer Nicholas Bellinger <nab@linux-iscsi.org> 1366877123 -0700

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>