dm: make dm_table_find_target return NULL

Currently, if we pass too high sector number to dm_table_find_target, it
returns zeroed dm_target structure and callers test if the structure is
zeroed with the macro dm_target_is_valid.

However, returning NULL is common practice to indicate errors.

This patch refactors the dm code, so that dm_table_find_target returns
NULL and its callers test the returned value for NULL. The macro
dm_target_is_valid is deleted. In alloc_targets, we no longer allocate an
extra zeroed target.

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

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 1e03bc89e20f..fb6f8fb1f13d 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1592,7 +1592,7 @@ static int target_message(struct file *filp, struct dm_ioctl *param, size_t para
         }
 
         ti = dm_table_find_target(table, tmsg->sector);
-        if (!dm_target_is_valid(ti)) {
+        if (!ti) {
                 DMWARN("Target message sector outside device.");
                 r = -EINVAL;
         } else if (ti->type->message)