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dm: split discards further if target sets max_discard_granularity

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The block core (bio_split_discard) will already split discards based
on the 'discard_granularity' and 'max_discard_sectors' queue_limits.
But the DM thin target also needs to ensure that it doesn't receive a
discard that spans a 'max_discard_sectors' boundary.

Introduce a dm_target 'max_discard_granularity' flag that if set will
cause DM core to split discard bios relative to 'max_discard_sectors'.
This treats 'discard_granularity' as a "min_discard_granularity" and
'max_discard_sectors' as a "max_discard_granularity".

Requested-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mike Snitzer 2023-03-01 12:48:43 -05:00
parent bb46c56165
commit 06961c487a
3 changed files with 27 additions and 8 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

25
drivers/md/dm.c
View file

@ -1162,7 +1162,8 @@ static inline sector_t max_io_len_target_boundary(struct dm_target *ti,
return ti->len - target_offset;
}
static sector_t max_io_len(struct dm_target *ti, sector_t sector)
static sector_t __max_io_len(struct dm_target *ti, sector_t sector,
unsigned int max_granularity)
{
sector_t target_offset = dm_target_offset(ti, sector);
sector_t len = max_io_len_target_boundary(ti, target_offset);
@ -1173,11 +1174,16 @@ static sector_t max_io_len(struct dm_target *ti, sector_t sector)
* explains why stacked chunk_sectors based splitting via
* bio_split_to_limits() isn't possible here.
*/
if (!ti->max_io_len)
if (!max_granularity)
return len;
return min_t(sector_t, len,
min(queue_max_sectors(ti->table->md->queue),
blk_chunk_sectors_left(target_offset, ti->max_io_len)));
blk_chunk_sectors_left(target_offset, max_granularity)));
}
static inline sector_t max_io_len(struct dm_target *ti, sector_t sector)
{
return __max_io_len(ti, sector, ti->max_io_len);
}
int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
@ -1565,12 +1571,13 @@ static void __send_empty_flush(struct clone_info *ci)
}
static void __send_changing_extent_only(struct clone_info *ci, struct dm_target *ti,
unsigned int num_bios)
unsigned int num_bios,
unsigned int max_granularity)
{
unsigned int len, bios;
len = min_t(sector_t, ci->sector_count,
max_io_len_target_boundary(ti, dm_target_offset(ti, ci->sector)));
__max_io_len(ti, ci->sector, max_granularity));
atomic_add(num_bios, &ci->io->io_count);
bios = __send_duplicate_bios(ci, ti, num_bios, &len);
@ -1606,10 +1613,16 @@ static blk_status_t __process_abnormal_io(struct clone_info *ci,
struct dm_target *ti)
{
unsigned int num_bios = 0;
unsigned int max_granularity = 0;
switch (bio_op(ci->bio)) {
case REQ_OP_DISCARD:
num_bios = ti->num_discard_bios;
if (ti->max_discard_granularity) {
struct queue_limits *limits =
dm_get_queue_limits(ti->table->md);
max_granularity = limits->max_discard_sectors;
}
break;
case REQ_OP_SECURE_ERASE:
num_bios = ti->num_secure_erase_bios;
@ -1630,7 +1643,7 @@ static blk_status_t __process_abnormal_io(struct clone_info *ci,
if (unlikely(!num_bios))
return BLK_STS_NOTSUPP;
__send_changing_extent_only(ci, ti, num_bios);
__send_changing_extent_only(ci, ti, num_bios, max_granularity);
return BLK_STS_OK;
}

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

@ -358,6 +358,12 @@ struct dm_target {
*/
bool discards_supported:1;
/*
* Set if this target requires that discards be split on both
* 'discard_granularity' and 'max_discard_sectors' boundaries.
*/
bool max_discard_granularity:1;
/*
* Set if we need to limit the number of in-flight bios when swapping.
*/

4
include/uapi/linux/dm-ioctl.h
View file

@ -286,9 +286,9 @@ enum {
#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
#define DM_VERSION_MAJOR 4
#define DM_VERSION_MINOR 47
#define DM_VERSION_MINOR 48
#define DM_VERSION_PATCHLEVEL 0
#define DM_VERSION_EXTRA "-ioctl (2022-07-28)"
#define DM_VERSION_EXTRA "-ioctl (2023-03-01)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */