dm: introduce DM_GET_TARGET_VERSION

This commit introduces a new ioctl DM_GET_TARGET_VERSION. It will load a
target that is specified in the "name" entry in the parameter structure
and return its version.

This functionality is intended to be used by cryptsetup, so that it can
query kernel capabilities before activating the device.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index fb6f8fb1f13d518feae0635c2f420ad21e75a418..ac83f5002ce5fe3a0483ea5630e389a9f29576ae 100644 (file)
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -601,17 +601,27 @@ static void list_version_get_info(struct target_type *tt, void *param)
     info->vers = align_ptr(((void *) ++info->vers) + strlen(tt->name) + 1);
 }
 
-static int list_versions(struct file *filp, struct dm_ioctl *param, size_t param_size)
+static int __list_versions(struct dm_ioctl *param, size_t param_size, const char *name)
 {
        size_t len, needed = 0;
        struct dm_target_versions *vers;
        struct vers_iter iter_info;
+       struct target_type *tt = NULL;
+
+       if (name) {
+               tt = dm_get_target_type(name);
+               if (!tt)
+                       return -EINVAL;
+       }
 
        /*
         * Loop through all the devices working out how much
         * space we need.
         */
-       dm_target_iterate(list_version_get_needed, &needed);
+       if (!tt)
+               dm_target_iterate(list_version_get_needed, &needed);
+       else
+               list_version_get_needed(tt, &needed);
 
        /*
         * Grab our output buffer.
@@ -632,13 +642,28 @@ static int list_versions(struct file *filp, struct dm_ioctl *param, size_t param
        /*
         * Now loop through filling out the names & versions.
         */
-       dm_target_iterate(list_version_get_info, &iter_info);
+       if (!tt)
+               dm_target_iterate(list_version_get_info, &iter_info);
+       else
+               list_version_get_info(tt, &iter_info);
        param->flags |= iter_info.flags;
 
  out:
+       if (tt)
+               dm_put_target_type(tt);
        return 0;
 }
 
+static int list_versions(struct file *filp, struct dm_ioctl *param, size_t param_size)
+{
+       return __list_versions(param, param_size, NULL);
+}
+
+static int get_target_version(struct file *filp, struct dm_ioctl *param, size_t param_size)
+{
+       return __list_versions(param, param_size, param->name);
+}
+
 static int check_name(const char *name)
 {
        if (strchr(name, '/')) {
@@ -1664,6 +1689,7 @@ static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags)
                {DM_TARGET_MSG_CMD, 0, target_message},
                {DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry},
                {DM_DEV_ARM_POLL, IOCTL_FLAGS_NO_PARAMS, dev_arm_poll},
+               {DM_GET_TARGET_VERSION, 0, get_target_version},
        };
 
        if (unlikely(cmd >= ARRAY_SIZE(_ioctls)))

diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h
index f396a82dfd3e61bb1810f4cacf6fcb9b9eefa37b..2df8ceca1f9b8479ff0537d421baec643a7de2cc 100644 (file)
--- a/include/uapi/linux/dm-ioctl.h
+++ b/include/uapi/linux/dm-ioctl.h
@@ -243,6 +243,7 @@ enum {
        DM_TARGET_MSG_CMD,
        DM_DEV_SET_GEOMETRY_CMD,
        DM_DEV_ARM_POLL_CMD,
+       DM_GET_TARGET_VERSION_CMD,
 };
 
 #define DM_IOCTL 0xfd
@@ -265,14 +266,15 @@ enum {
 #define DM_TABLE_STATUS  _IOWR(DM_IOCTL, DM_TABLE_STATUS_CMD, struct dm_ioctl)
 
 #define DM_LIST_VERSIONS _IOWR(DM_IOCTL, DM_LIST_VERSIONS_CMD, struct dm_ioctl)
+#define DM_GET_TARGET_VERSION _IOWR(DM_IOCTL, DM_GET_TARGET_VERSION_CMD, struct dm_ioctl)
 
 #define DM_TARGET_MSG   _IOWR(DM_IOCTL, DM_TARGET_MSG_CMD, struct dm_ioctl)
 #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       40
+#define DM_VERSION_MINOR       41
 #define DM_VERSION_PATCHLEVEL  0
-#define DM_VERSION_EXTRA       "-ioctl (2019-01-18)"
+#define DM_VERSION_EXTRA       "-ioctl (2019-09-16)"
 
 /* Status bits */
 #define DM_READONLY_FLAG       (1 << 0) /* In/Out */