[PATCH] dm: fix a comment

From: Kevin Corry <kevcorry@us.ibm.com>

Clarify the comment regarding the "next" field in struct dm_target_spec.  The
"next" field has different behavior if you're performing a DM_TABLE_STATUS
command than it does if you're performing a DM_TABLE_LOAD command.

See populate_table() and retrieve_status() in drivers/md/dm-ioctl.c for more
details on how this field is used.

diff --git a/include/linux/dm-ioctl.h b/include/linux/dm-ioctl.h
index 036f98bb840a93ac525c58c6b08a9131bb8c7170..03f99db7ad7b71502a5b7a72219fd487ebec8e10 100644 (file)
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -129,8 +129,14 @@ struct dm_target_spec {
        int32_t status;         /* used when reading from kernel only */
 
        /*
-        * Offset in bytes (from the start of this struct) to
-        * next target_spec.
+        * Location of the next dm_target_spec.
+        * - When specifying targets on a DM_TABLE_LOAD command, this value is
+        *   the number of bytes from the start of the "current" dm_target_spec
+        *   to the start of the "next" dm_target_spec.
+        * - When retrieving targets on a DM_TABLE_STATUS command, this value
+        *   is the number of bytes from the start of the first dm_target_spec
+        *   (that follows the dm_ioctl struct) to the start of the "next"
+        *   dm_target_spec.
         */
        uint32_t next;