2 files changed, 67 insertions, 16 deletions

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index d06dd39856f..a3d20265ffc 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -523,8 +523,6 @@ static int list_versions(struct dm_ioctl *param, size_t param_size)
         return 0;
 }
 
-
-
 static int check_name(const char *name)
 {
         if (strchr(name, '/')) {
@@ -536,6 +534,40 @@ static int check_name(const char *name)
 }
 
 /*
+ * 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 @@ static int __dev_status(struct mapped_device *md, struct dm_ioctl *param)
          */
         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 @@ static int dev_wait(struct dm_ioctl *param, size_t param_size)
         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 @@ static int table_deps(struct dm_ioctl *param, size_t param_size)
         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 @@ static int table_status(struct dm_ioctl *param, size_t param_size)
         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;
 }
diff --git a/include/linux/dm-ioctl.h b/include/linux/dm-ioctl.h
index 2ab84c83c31..aa95508d2f9 100644
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2001 - 2003 Sistina Software (UK) Limited.
- * Copyright (C) 2004 - 2005 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004 - 2009 Red Hat, Inc. All rights reserved.
  *
  * This file is released under the LGPL.
  */
@@ -266,9 +266,9 @@ enum {
 #define DM_DEV_SET_GEOMETRY     _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR        4
-#define DM_VERSION_MINOR        15
+#define DM_VERSION_MINOR        16
 #define DM_VERSION_PATCHLEVEL   0
-#define DM_VERSION_EXTRA        "-ioctl (2009-04-01)"
+#define DM_VERSION_EXTRA        "-ioctl (2009-11-05)"
 
 /* Status bits */
 #define DM_READONLY_FLAG        (1 << 0) /* In/Out */
@@ -309,4 +309,11 @@ enum {
  */
 #define DM_NOFLUSH_FLAG         (1 << 11) /* In */
 
+/*
+ * If set, any table information returned will relate to the inactive
+ * table instead of the live one.  Always check DM_INACTIVE_PRESENT_FLAG
+ * is set before using the data returned.
+ */
+#define DM_QUERY_INACTIVE_TABLE_FLAG    (1 << 12) /* In */
+
 #endif                          /* _LINUX_DM_IOCTL_H */