dm thin: add error_if_no_space feature
If the pool runs out of data or metadata space, the pool can either
queue or error the IO destined to the data device. The default is to
queue the IO until more space is added.
An admin may now configure the pool to error IO when no space is
available by setting the 'error_if_no_space' feature when loading the
thin-pool table.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt
index 50c44cf..8a7a3d4 100644
--- a/Documentation/device-mapper/thin-provisioning.txt
+++ b/Documentation/device-mapper/thin-provisioning.txt
@@ -235,6 +235,8 @@
read_only: Don't allow any changes to be made to the pool
metadata.
+ error_if_no_space: Error IOs, instead of queueing, if no space.
+
Data block size must be between 64KB (128 sectors) and 1GB
(2097152 sectors) inclusive.
@@ -276,6 +278,11 @@
contain the string 'Fail'. The userspace recovery tools
should then be used.
+ error_if_no_space|queue_if_no_space
+ If the pool runs out of data or metadata space, the pool will
+ either queue or error the IO destined to the data device. The
+ default is to queue the IO until more space is added.
+
iii) Messages
create_thin <dev id>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 53252d2a..075c39e 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -144,6 +144,7 @@
bool zero_new_blocks:1;
bool discard_enabled:1;
bool discard_passdown:1;
+ bool error_if_no_space:1;
};
struct thin_c;
@@ -1440,6 +1441,9 @@
{
unsigned long flags;
+ if (pool->pf.error_if_no_space)
+ return;
+
spin_lock_irqsave(&pool->lock, flags);
pool->no_free_space = true;
spin_unlock_irqrestore(&pool->lock, flags);
@@ -1723,6 +1727,7 @@
pf->zero_new_blocks = true;
pf->discard_enabled = true;
pf->discard_passdown = true;
+ pf->error_if_no_space = false;
}
static void __pool_destroy(struct pool *pool)
@@ -1968,6 +1973,9 @@
else if (!strcasecmp(arg_name, "read_only"))
pf->mode = PM_READ_ONLY;
+ else if (!strcasecmp(arg_name, "error_if_no_space"))
+ pf->error_if_no_space = true;
+
else {
ti->error = "Unrecognised pool feature requested";
r = -EINVAL;
@@ -2038,6 +2046,8 @@
* skip_block_zeroing: skips the zeroing of newly-provisioned blocks.
* ignore_discard: disable discard
* no_discard_passdown: don't pass discards down to the data device
+ * read_only: Don't allow any changes to be made to the pool metadata.
+ * error_if_no_space: error IOs, instead of queueing, if no space.
*/
static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
{
@@ -2555,7 +2565,8 @@
unsigned sz, unsigned maxlen)
{
unsigned count = !pf->zero_new_blocks + !pf->discard_enabled +
- !pf->discard_passdown + (pf->mode == PM_READ_ONLY);
+ !pf->discard_passdown + (pf->mode == PM_READ_ONLY) +
+ pf->error_if_no_space;
DMEMIT("%u ", count);
if (!pf->zero_new_blocks)
@@ -2569,6 +2580,9 @@
if (pf->mode == PM_READ_ONLY)
DMEMIT("read_only ");
+
+ if (pf->error_if_no_space)
+ DMEMIT("error_if_no_space ");
}
/*
@@ -2663,11 +2677,16 @@
DMEMIT("rw ");
if (!pool->pf.discard_enabled)
- DMEMIT("ignore_discard");
+ DMEMIT("ignore_discard ");
else if (pool->pf.discard_passdown)
- DMEMIT("discard_passdown");
+ DMEMIT("discard_passdown ");
else
- DMEMIT("no_discard_passdown");
+ DMEMIT("no_discard_passdown ");
+
+ if (pool->pf.error_if_no_space)
+ DMEMIT("error_if_no_space ");
+ else
+ DMEMIT("queue_if_no_space ");
break;
@@ -2766,7 +2785,7 @@
.name = "thin-pool",
.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
DM_TARGET_IMMUTABLE,
- .version = {1, 9, 0},
+ .version = {1, 10, 0},
.module = THIS_MODULE,
.ctr = pool_ctr,
.dtr = pool_dtr,
@@ -3053,7 +3072,7 @@
static struct target_type thin_target = {
.name = "thin",
- .version = {1, 9, 0},
+ .version = {1, 10, 0},
.module = THIS_MODULE,
.ctr = thin_ctr,
.dtr = thin_dtr,