dm snapshot: add allocated metadata to snapshot status

Add number of sectors used by metadata to the end of the snapshot's status
line.

Renamed dm_exception_store_type's 'fraction_full' to 'usage'.  Renamed
arguments to be clearer about what is being returned.  Also added
'metadata_sectors'.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

4 files changed, 41 insertions, 24 deletions

diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index 92749696e359..366c8b1fca37 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -86,9 +86,9 @@ struct dm_exception_store_type {
         /*
          * Return how full the snapshot is.
          */
-        void (*fraction_full) (struct dm_exception_store *store,
-                               sector_t *numerator,
-                               sector_t *denominator);
+        void (*usage) (struct dm_exception_store *store,
+                       sector_t *total_sectors, sector_t *sectors_allocated,
+                       sector_t *metadata_sectors);
 
         /* For internal device-mapper use only. */
         struct list_head list;
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 24b8acd1be83..767065f6c5f3 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -489,11 +489,22 @@ static struct pstore *get_info(struct dm_exception_store *store)
         return (struct pstore *) store->context;
 }
 
-static void persistent_fraction_full(struct dm_exception_store *store,
-                                     sector_t *numerator, sector_t *denominator)
+static void persistent_usage(struct dm_exception_store *store,
+                             sector_t *total_sectors,
+                             sector_t *sectors_allocated,
+                             sector_t *metadata_sectors)
 {
-        *numerator = get_info(store)->next_free * store->chunk_size;
-        *denominator = get_dev_size(store->cow->bdev);
+        struct pstore *ps = get_info(store);
+
+        *sectors_allocated = ps->next_free * store->chunk_size;
+        *total_sectors = get_dev_size(store->cow->bdev);
+
+        /*
+         * First chunk is the fixed header.
+         * Then there are (ps->current_area + 1) metadata chunks, each one
+         * separated from the next by ps->exceptions_per_area data chunks.
+         */
+        *metadata_sectors = (ps->current_area + 2) * store->chunk_size;
 }
 
 static void persistent_dtr(struct dm_exception_store *store)
@@ -738,7 +749,7 @@ static struct dm_exception_store_type _persistent_type = {
         .prepare_exception = persistent_prepare_exception,
         .commit_exception = persistent_commit_exception,
         .drop_snapshot = persistent_drop_snapshot,
-        .fraction_full = persistent_fraction_full,
+        .usage = persistent_usage,
         .status = persistent_status,
 };
 
@@ -751,7 +762,7 @@ static struct dm_exception_store_type _persistent_compat_type = {
         .prepare_exception = persistent_prepare_exception,
         .commit_exception = persistent_commit_exception,
         .drop_snapshot = persistent_drop_snapshot,
-        .fraction_full = persistent_fraction_full,
+        .usage = persistent_usage,
         .status = persistent_status,
 };
 
diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c
index 267801b34ff6..245a50c7337e 100644
--- a/drivers/md/dm-snap-transient.c
+++ b/drivers/md/dm-snap-transient.c
@@ -59,11 +59,14 @@ static void transient_commit_exception(struct dm_exception_store *store,
         callback(callback_context, 1);
 }
 
-static void transient_fraction_full(struct dm_exception_store *store,
-                                    sector_t *numerator, sector_t *denominator)
+static void transient_usage(struct dm_exception_store *store,
+                            sector_t *total_sectors,
+                            sector_t *sectors_allocated,
+                            sector_t *metadata_sectors)
 {
-        *numerator = ((struct transient_c *) store->context)->next_free;
-        *denominator = get_dev_size(store->cow->bdev);
+        *sectors_allocated = ((struct transient_c *) store->context)->next_free;
+        *total_sectors = get_dev_size(store->cow->bdev);
+        *metadata_sectors = 0;
 }
 
 static int transient_ctr(struct dm_exception_store *store,
@@ -106,7 +109,7 @@ static struct dm_exception_store_type _transient_type = {
         .read_metadata = transient_read_metadata,
         .prepare_exception = transient_prepare_exception,
         .commit_exception = transient_commit_exception,
-        .fraction_full = transient_fraction_full,
+        .usage = transient_usage,
         .status = transient_status,
 };
 
@@ -118,7 +121,7 @@ static struct dm_exception_store_type _transient_compat_type = {
         .read_metadata = transient_read_metadata,
         .prepare_exception = transient_prepare_exception,
         .commit_exception = transient_commit_exception,
-        .fraction_full = transient_fraction_full,
+        .usage = transient_usage,
         .status = transient_status,
 };
 
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index cb4c2c3a43f0..8bd77cbd7e45 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1174,14 +1174,17 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
                 if (!snap->valid)
                         DMEMIT("Invalid");
                 else {
-                        if (snap->store->type->fraction_full) {
-                                sector_t numerator, denominator;
-                                snap->store->type->fraction_full(snap->store,
-                                                                 &numerator,
-                                                                 &denominator);
-                                DMEMIT("%llu/%llu",
-                                       (unsigned long long)numerator,
-                                       (unsigned long long)denominator);
+                        if (snap->store->type->usage) {
+                                sector_t total_sectors, sectors_allocated,
+                                         metadata_sectors;
+                                snap->store->type->usage(snap->store,
+                                                         &total_sectors,
+                                                         &sectors_allocated,
+                                                         &metadata_sectors);
+                                DMEMIT("%llu/%llu %llu",
+                                       (unsigned long long)sectors_allocated,
+                                       (unsigned long long)total_sectors,
+                                       (unsigned long long)metadata_sectors);
                         }
                         else
                                 DMEMIT("Unknown");
@@ -1462,7 +1465,7 @@ static struct target_type origin_target = {
 
 static struct target_type snapshot_target = {
         .name    = "snapshot",
-        .version = {1, 7, 0},
+        .version = {1, 8, 0},
         .module  = THIS_MODULE,
         .ctr     = snapshot_ctr,
         .dtr     = snapshot_dtr,