[PATCH v2] xfs: hide unused variable

[Arnd Bergmann <arnd@arndb.de>]

The newly added xfs_finish_page_writeback() function causes
a harmless gcc warning when debugging is disabled:

fs/xfs/xfs_aops.c: In function 'xfs_finish_page_writeback':
fs/xfs/xfs_aops.c:97:16: error: unused variable 'blockmask' [-Werror=unused-variable]
  unsigned int  blockmask = (1 << inode->i_blkbits) - 1;
                ^~~~~~~~~

This adds an #ifdef around the variable declaration to hide
it whenever the ASSERT macro is defined as a stub, following
the same style as used elsewhere in xfs.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 37992c18bba3 ("xfs: don't release bios on completion immediately")
---
I originally sent this on April 16 when the warning first showed up
but got no reply. Sending it again now as the warning is still present
in linux-next.

 fs/xfs/xfs_aops.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 8a5244e4c2e9..62d938c46f31 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -94,7 +94,9 @@ xfs_finish_page_writeback(
 	struct bio_vec		*bvec,
 	int			error)
 {
+#if defined(DEBUG) || defined(XFS_WARN)
 	unsigned int		blockmask = (1 << inode->i_blkbits) - 1;
+#endif
 	unsigned int		end = bvec->bv_offset + bvec->bv_len - 1;
 	struct buffer_head	*head, *bh;
 	unsigned int		off = 0;
-- 
2.7.0