dm-zero, dm-error: support discards
This patch adds discard support to dm-zero and dm-error. dm-zero ignores
the discards, dm-error return -EIO. It is useful when the user combines
dm-zero or dm-error with other discard-supporting targets in the same
table; without dm-zero or dm-error support, discards would be disabled for
the whole combined device.
Signed-off-by: Mikulas Patocka <mpato...@redhat.com>
---
drivers/md/dm-table.c | 6 +++++-
drivers/md/dm-target.c | 11 ++++++++++-
drivers/md/dm-zero.c | 12 +++++++++++-
3 files changed, 26 insertions(+), 3 deletions(-)
Index: linux-2.6/drivers/md/dm-zero.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-zero.c
+++ linux-2.6/drivers/md/dm-zero.c
@@ -27,6 +27,7 @@ static int zero_ctr(struct dm_target *ti
* Silently drop discards, avoiding -EOPNOTSUPP.
*/
ti->num_discard_bios = 1;
+ ti->discards_supported = true;
return 0;
}
@@ -45,6 +46,7 @@ static int zero_map(struct dm_target *ti
zero_fill_bio(bio);
break;
case REQ_OP_WRITE:
+ case REQ_OP_DISCARD:
/* writes get silently dropped */
break;
default:
@@ -57,13 +59,21 @@ static int zero_map(struct dm_target *ti
return DM_MAPIO_SUBMITTED;
}
+static void zero_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+ limits->max_discard_sectors = UINT_MAX;
+ limits->max_hw_discard_sectors = UINT_MAX;
+ limits->discard_granularity = 512;
+}
+
static struct target_type zero_target = {
.name = "zero",
- .version = {1, 1, 0},
+ .version = {1, 2, 0},
.features = DM_TARGET_NOWAIT,
.module = THIS_MODULE,
.ctr = zero_ctr,
.map = zero_map,
+ .io_hints = zero_io_hints,
};
static int __init dm_zero_init(void)
Index: linux-2.6/drivers/md/dm-table.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-table.c
+++ linux-2.6/drivers/md/dm-table.c
@@ -1670,8 +1670,12 @@ int dm_calculate_queue_limits(struct dm_
blk_set_stacking_limits(&ti_limits);
- if (!ti->type->iterate_devices)
+ if (!ti->type->iterate_devices) {
+ /* Set I/O hints portion of queue limits */
+ if (ti->type->io_hints)
+ ti->type->io_hints(ti, &ti_limits);
goto combine_limits;
+ }
/*
* Combine queue limits of all the devices this target uses.
Index: linux-2.6/drivers/md/dm-target.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-target.c
+++ linux-2.6/drivers/md/dm-target.c
@@ -119,6 +119,7 @@ static int io_err_ctr(struct dm_target *
* Return error for discards instead of -EOPNOTSUPP
*/
tt->num_discard_bios = 1;
+ tt->discards_supported = true;
return 0;
}
@@ -145,6 +146,13 @@ static void io_err_release_clone_rq(stru
{
}
+static void io_err_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+ limits->max_discard_sectors = UINT_MAX;
+ limits->max_hw_discard_sectors = UINT_MAX;
+ limits->discard_granularity = 512;
+}
+
static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
long nr_pages, enum dax_access_mode mode, void **kaddr,
pfn_t *pfn)
@@ -154,13 +162,14 @@ static long io_err_dax_direct_access(str
static struct target_type error_target = {
.name = "error",
- .version = {1, 5, 0},
+ .version = {1, 6, 0},
.features = DM_TARGET_WILDCARD,
.ctr = io_err_ctr,
.dtr = io_err_dtr,
.map = io_err_map,
.clone_and_map_rq = io_err_clone_and_map_rq,
.release_clone_rq = io_err_release_clone_rq,
+ .io_hints = io_err_io_hints,
.direct_access = io_err_dax_direct_access,
};
--
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