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dm thin: tidy discard support 

A little thin discard code refactoring to make the next patch (dm thin:
fix discard support for data devices) more readable.
Pull out a couple of functions (and uses bools instead of unsigned for
features).

No functional changes.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mike Snitzer 2012-09-26 23:45:46 +01:00 committed by Alasdair G Kergon
parent 3ae7065616
commit 9bc142dd75
1 changed files with 39 additions and 25 deletions
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64
drivers/md/dm-thin.c
View File

@ -509,9 +509,9 @@ enum pool_mode {
struct pool_features {
enum pool_mode mode;
unsigned zero_new_blocks:1;
unsigned discard_enabled:1;
unsigned discard_passdown:1;
bool zero_new_blocks:1;
bool discard_enabled:1;
bool discard_passdown:1;
};
struct thin_c;
@ -1839,6 +1839,32 @@ static void __requeue_bios(struct pool *pool)
/*----------------------------------------------------------------
* Binding of control targets to a pool object
*--------------------------------------------------------------*/
static bool data_dev_supports_discard(struct pool_c *pt)
{
struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
return q && blk_queue_discard(q);
}
/*
* If discard_passdown was enabled verify that the data device
* supports discards. Disable discard_passdown if not; otherwise
* -EOPNOTSUPP will be returned.
*/
static void disable_passdown_if_not_supported(struct pool_c *pt,
struct pool_features *pf)
{
char buf[BDEVNAME_SIZE];
if (!pf->discard_passdown || data_dev_supports_discard(pt))
return;
DMWARN("Discard unsupported by data device (%s): Disabling discard passdown.",
bdevname(pt->data_dev->bdev, buf));
pf->discard_passdown = false;
}
static int bind_control_target(struct pool *pool, struct dm_target *ti)
{
struct pool_c *pt = ti->private;
@ -1855,23 +1881,9 @@ static int bind_control_target(struct pool *pool, struct dm_target *ti)
pool->ti = ti;
pool->low_water_blocks = pt->low_water_blocks;
pool->pf = pt->pf;
set_pool_mode(pool, new_mode);
/*
* If discard_passdown was enabled verify that the data device
* supports discards. Disable discard_passdown if not; otherwise
* -EOPNOTSUPP will be returned.
*/
/* FIXME: pull this out into a sep fn. */
if (pt->pf.discard_passdown) {
struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
if (!q || !blk_queue_discard(q)) {
char buf[BDEVNAME_SIZE];
DMWARN("Discard unsupported by data device (%s): Disabling discard passdown.",
bdevname(pt->data_dev->bdev, buf));
pool->pf.discard_passdown = 0;
}
}
disable_passdown_if_not_supported(pt, &pool->pf);
set_pool_mode(pool, new_mode);
return 0;
}
@ -1889,9 +1901,9 @@ static void unbind_control_target(struct pool *pool, struct dm_target *ti)
static void pool_features_init(struct pool_features *pf)
{
pf->mode = PM_WRITE;
pf->zero_new_blocks = 1;
pf->discard_enabled = 1;
pf->discard_passdown = 1;
pf->zero_new_blocks = true;
pf->discard_enabled = true;
pf->discard_passdown = true;
}
static void __pool_destroy(struct pool *pool)
@ -2119,13 +2131,13 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
argc--;
if (!strcasecmp(arg_name, "skip_block_zeroing"))
pf->zero_new_blocks = 0;
pf->zero_new_blocks = false;
else if (!strcasecmp(arg_name, "ignore_discard"))
pf->discard_enabled = 0;
pf->discard_enabled = false;
else if (!strcasecmp(arg_name, "no_discard_passdown"))
pf->discard_passdown = 0;
pf->discard_passdown = false;
else if (!strcasecmp(arg_name, "read_only"))
pf->mode = PM_READ_ONLY;
@ -2261,6 +2273,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
pt->low_water_blocks = low_water_blocks;
pt->pf = pf;
ti->num_flush_requests = 1;
/*
* Only need to enable discards if the pool should pass
* them down to the data device. The thin device's discard
@ -2268,6 +2281,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
*/
if (pf.discard_enabled && pf.discard_passdown) {
ti->num_discard_requests = 1;
/*
* Setting 'discards_supported' circumvents the normal
* stacking of discard limits (this keeps the pool and