[PATCH] sbitmap, scsi/target: add seq_file forward declaration

[Arnd Bergmann <arnd@arndb.de>]

The target core runs into a warning in the linux/sbitmap.h
file in some configurations:

In file included from include/target/target_core_base.h:7,
                 from drivers/target/target_core_fabric_lib.c:41:
include/linux/sbitmap.h:331:46: error: 'struct seq_file' declared inside parameter list will not be visible outside of this definition or declaration [-Werror]
 void sbitmap_show(struct sbitmap *sb, struct seq_file *m);
                                              ^~~~~~~~

In general, headers should not depend on others being included first,
so this fixes it with a forward declaration for that struct name, but
we probably want to merge the patch through the scsi tree to help
bisection.

Fixes: 10e9cbb6b531 ("scsi: target: Convert target drivers to use sbitmap")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/sbitmap.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h
index e6539536dea9..cc54b9f7ff8b 100644
--- a/include/linux/sbitmap.h
+++ b/include/linux/sbitmap.h
@@ -321,6 +321,8 @@ static inline int sbitmap_test_bit(struct sbitmap *sb, unsigned int bitnr)
 
 unsigned int sbitmap_weight(const struct sbitmap *sb);
 
+struct seq_file;
+
 /**
  * sbitmap_show() - Dump &struct sbitmap information to a &struct seq_file.
  * @sb: Bitmap to show.
-- 
2.9.0