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dm: introduce split_discard_requests 

This patch introduces a new variable split_discard_requests. It can be
set by targets so that discard requests are split on max_io_len
boundaries.

When split_discard_requests is not set, discard requests are only split on
boundaries between targets, as was the case before this patch.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
hifive-unleashed-5.1
Mikulas Patocka 2012-07-27 15:08:03 +01:00 committed by Alasdair G Kergon
parent 55f2b8bdb0
commit 7acf0277ce
2 changed files with 10 additions and 1 deletions
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5
drivers/md/dm.c
View File

@ -1215,7 +1215,10 @@ static int __clone_and_map_discard(struct clone_info *ci)
if (!ti->num_discard_requests)
return -EOPNOTSUPP;
len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
if (!ti->split_discard_requests)
len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
else
len = min(ci->sector_count, max_io_len(ci->sector, ti));
__issue_target_requests(ci, ti, ti->num_discard_requests, len);

6
include/linux/device-mapper.h
View File

@ -217,6 +217,12 @@ struct dm_target {
*/
unsigned discards_supported:1;
/*
* Set if the target required discard request to be split
* on max_io_len boundary.
*/
unsigned split_discard_requests:1;
/*
* Set if this target does not return zeroes on discarded blocks.
*/