On 09/29/2016 02:39 AM, Darrick J. Wong wrote:

After much discussion, it seems that the fallocate feature flag
FALLOC_FL_ZERO_RANGE maps nicely to SCSI WRITE SAME; and the feature
FALLOC_FL_PUNCH_HOLE maps nicely to the devices that have been
whitelisted for zeroing SCSI UNMAP.  Punch still requires that
FALLOC_FL_KEEP_SIZE is set.  A length that goes past the end of the
device will be clamped to the device size if KEEP_SIZE is set; or will
return -EINVAL if not.  Both start and length must be aligned to the
device's logical block size.

Since the semantics of fallocate are fairly well established already,
wire up the two pieces.  The other fallocate variants (collapse range,
insert range, and allocate blocks) are not supported.

Signed-off-by: Darrick J. Wong <redacted>
---
v2: Incorporate feedback from Christoph & Linus.  Tentatively add
a requirement that the fallocate arguments be aligned to logical block
size, and put in a few XXX comments ahead of LSF discussion.
v3: Forward port to 4.7.
v4: Forward port to 4.8.
---
 fs/block_dev.c |   78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/open.c      |    3 +-
 2 files changed, 80 insertions(+), 1 deletion(-)

Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
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