dm ioctl: retrieve status from inactive table
Add the flag DM_QUERY_INACTIVE_TABLE_FLAG to the ioctls to return
infomation about the loaded-but-not-yet-active table instead of the live
table. Prior to this patch it was impossible to obtain this information
until the device had been 'resumed'.
Userspace dmsetup and libdevmapper support the flag as of version 1.02.40.
e.g. dmsetup info --inactive vg1-lv1
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index d06dd39..a3d2026 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -523,8 +523,6 @@
return 0;
}
-
-
static int check_name(const char *name)
{
if (strchr(name, '/')) {
@@ -536,6 +534,40 @@
}
/*
+ * On successful return, the caller must not attempt to acquire
+ * _hash_lock without first calling dm_table_put, because dm_table_destroy
+ * waits for this dm_table_put and could be called under this lock.
+ */
+static struct dm_table *dm_get_inactive_table(struct mapped_device *md)
+{
+ struct hash_cell *hc;
+ struct dm_table *table = NULL;
+
+ down_read(&_hash_lock);
+ hc = dm_get_mdptr(md);
+ if (!hc || hc->md != md) {
+ DMWARN("device has been removed from the dev hash table.");
+ goto out;
+ }
+
+ table = hc->new_map;
+ if (table)
+ dm_table_get(table);
+
+out:
+ up_read(&_hash_lock);
+
+ return table;
+}
+
+static struct dm_table *dm_get_live_or_inactive_table(struct mapped_device *md,
+ struct dm_ioctl *param)
+{
+ return (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) ?
+ dm_get_inactive_table(md) : dm_get_live_table(md);
+}
+
+/*
* Fills in a dm_ioctl structure, ready for sending back to
* userland.
*/
@@ -559,18 +591,30 @@
*/
param->open_count = dm_open_count(md);
- if (get_disk_ro(disk))
- param->flags |= DM_READONLY_FLAG;
-
param->event_nr = dm_get_event_nr(md);
+ param->target_count = 0;
table = dm_get_live_table(md);
if (table) {
- param->flags |= DM_ACTIVE_PRESENT_FLAG;
- param->target_count = dm_table_get_num_targets(table);
+ if (!(param->flags & DM_QUERY_INACTIVE_TABLE_FLAG)) {
+ if (get_disk_ro(disk))
+ param->flags |= DM_READONLY_FLAG;
+ param->target_count = dm_table_get_num_targets(table);
+ }
dm_table_put(table);
- } else
- param->target_count = 0;
+
+ param->flags |= DM_ACTIVE_PRESENT_FLAG;
+ }
+
+ if (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) {
+ table = dm_get_inactive_table(md);
+ if (table) {
+ if (!(dm_table_get_mode(table) & FMODE_WRITE))
+ param->flags |= DM_READONLY_FLAG;
+ param->target_count = dm_table_get_num_targets(table);
+ dm_table_put(table);
+ }
+ }
return 0;
}
@@ -993,7 +1037,7 @@
if (r)
goto out;
- table = dm_get_live_table(md);
+ table = dm_get_live_or_inactive_table(md, param);
if (table) {
retrieve_status(table, param, param_size);
dm_table_put(table);
@@ -1226,7 +1270,7 @@
if (r)
goto out;
- table = dm_get_live_table(md);
+ table = dm_get_live_or_inactive_table(md, param);
if (table) {
retrieve_deps(table, param, param_size);
dm_table_put(table);
@@ -1255,13 +1299,13 @@
if (r)
goto out;
- table = dm_get_live_table(md);
+ table = dm_get_live_or_inactive_table(md, param);
if (table) {
retrieve_status(table, param, param_size);
dm_table_put(table);
}
- out:
+out:
dm_put(md);
return r;
}