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-rw-r--r--Documentation/device-mapper/snapshot.txt10
-rw-r--r--drivers/md/dm-exception-store.c6
-rw-r--r--drivers/md/dm-exception-store.h5
-rw-r--r--drivers/md/dm-snap-persistent.c17
-rw-r--r--drivers/md/dm-snap-transient.c3
-rw-r--r--drivers/md/dm-snap.c14
6 files changed, 37 insertions, 18 deletions
diff --git a/Documentation/device-mapper/snapshot.txt b/Documentation/device-mapper/snapshot.txt
index 0d5bc46..ad6949b 100644
--- a/Documentation/device-mapper/snapshot.txt
+++ b/Documentation/device-mapper/snapshot.txt
@@ -41,9 +41,13 @@ useless and be disabled, returning errors. So it is important to monitor
the amount of free space and expand the <COW device> before it fills up.
<persistent?> is P (Persistent) or N (Not persistent - will not survive
-after reboot).
-The difference is that for transient snapshots less metadata must be
-saved on disk - they can be kept in memory by the kernel.
+after reboot). O (Overflow) can be added as a persistent store option
+to allow userspace to advertise its support for seeing "Overflow" in the
+snapshot status. So supported store types are "P", "PO" and "N".
+
+The difference between persistent and transient is with transient
+snapshots less metadata must be saved on disk - they can be kept in
+memory by the kernel.
* snapshot-merge <origin> <COW device> <persistent> <chunksize>
diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index ebaa4f8..192bb8b 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -203,7 +203,7 @@ int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
return -EINVAL;
}
- tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
+ tmp_store = kzalloc(sizeof(*tmp_store), GFP_KERNEL);
if (!tmp_store) {
ti->error = "Exception store allocation failed";
return -ENOMEM;
@@ -215,7 +215,7 @@ int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
else if (persistent == 'N')
type = get_type("N");
else {
- ti->error = "Persistent flag is not P or N";
+ ti->error = "Exception store type is not P or N";
r = -EINVAL;
goto bad_type;
}
@@ -233,7 +233,7 @@ int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
if (r)
goto bad;
- r = type->ctr(tmp_store, 0, NULL);
+ r = type->ctr(tmp_store, (strlen(argv[0]) > 1 ? &argv[0][1] : NULL));
if (r) {
ti->error = "Exception store type constructor failed";
goto bad;
diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index 0b25362..fae34e7 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -42,8 +42,7 @@ struct dm_exception_store_type {
const char *name;
struct module *module;
- int (*ctr) (struct dm_exception_store *store,
- unsigned argc, char **argv);
+ int (*ctr) (struct dm_exception_store *store, char *options);
/*
* Destroys this object when you've finished with it.
@@ -123,6 +122,8 @@ struct dm_exception_store {
unsigned chunk_shift;
void *context;
+
+ bool userspace_supports_overflow;
};
/*
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index bf71583..aeacad9 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -7,6 +7,7 @@
#include "dm-exception-store.h"
+#include <linux/ctype.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/vmalloc.h>
@@ -843,8 +844,7 @@ static void persistent_drop_snapshot(struct dm_exception_store *store)
DMWARN("write header failed");
}
-static int persistent_ctr(struct dm_exception_store *store,
- unsigned argc, char **argv)
+static int persistent_ctr(struct dm_exception_store *store, char *options)
{
struct pstore *ps;
@@ -873,6 +873,16 @@ static int persistent_ctr(struct dm_exception_store *store,
return -ENOMEM;
}
+ if (options) {
+ char overflow = toupper(options[0]);
+ if (overflow == 'O')
+ store->userspace_supports_overflow = true;
+ else {
+ DMERR("Unsupported persistent store option: %s", options);
+ return -EINVAL;
+ }
+ }
+
store->context = ps;
return 0;
@@ -888,7 +898,8 @@ static unsigned persistent_status(struct dm_exception_store *store,
case STATUSTYPE_INFO:
break;
case STATUSTYPE_TABLE:
- DMEMIT(" P %llu", (unsigned long long)store->chunk_size);
+ DMEMIT(" %s %llu", store->userspace_supports_overflow ? "PO" : "P",
+ (unsigned long long)store->chunk_size);
}
return sz;
diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c
index 1ce9a25..9b7c8c8 100644
--- a/drivers/md/dm-snap-transient.c
+++ b/drivers/md/dm-snap-transient.c
@@ -70,8 +70,7 @@ static void transient_usage(struct dm_exception_store *store,
*metadata_sectors = 0;
}
-static int transient_ctr(struct dm_exception_store *store,
- unsigned argc, char **argv)
+static int transient_ctr(struct dm_exception_store *store, char *options)
{
struct transient_c *tc;
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index c0bcd65..c06b74e 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1098,7 +1098,7 @@ static void stop_merge(struct dm_snapshot *s)
}
/*
- * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size>
+ * Construct a snapshot mapping: <origin_dev> <COW-dev> <p|po|n> <chunk-size>
*/
static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
@@ -1302,6 +1302,7 @@ static void __handover_exceptions(struct dm_snapshot *snap_src,
u.store_swap = snap_dest->store;
snap_dest->store = snap_src->store;
+ snap_dest->store->userspace_supports_overflow = u.store_swap->userspace_supports_overflow;
snap_src->store = u.store_swap;
snap_dest->store->snap = snap_dest;
@@ -1739,8 +1740,11 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
pe = __find_pending_exception(s, pe, chunk);
if (!pe) {
- s->snapshot_overflowed = 1;
- DMERR("Snapshot overflowed: Unable to allocate exception.");
+ if (s->store->userspace_supports_overflow) {
+ s->snapshot_overflowed = 1;
+ DMERR("Snapshot overflowed: Unable to allocate exception.");
+ } else
+ __invalidate_snapshot(s, -ENOMEM);
r = -EIO;
goto out_unlock;
}
@@ -2365,7 +2369,7 @@ static struct target_type origin_target = {
static struct target_type snapshot_target = {
.name = "snapshot",
- .version = {1, 14, 0},
+ .version = {1, 15, 0},
.module = THIS_MODULE,
.ctr = snapshot_ctr,
.dtr = snapshot_dtr,
@@ -2379,7 +2383,7 @@ static struct target_type snapshot_target = {
static struct target_type merge_target = {
.name = dm_snapshot_merge_target_name,
- .version = {1, 3, 0},
+ .version = {1, 4, 0},
.module = THIS_MODULE,
.ctr = snapshot_ctr,
.dtr = snapshot_dtr,
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