linux-kernel - [PATCH 1/2] dax: hide block device code in #ifdef

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Message-Id: <20170515134508.2713243-1-arnd@arndb.de>
Date:   Mon, 15 May 2017 15:44:00 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Jan Kara <jack@...e.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-xfs@...r.kernel.org,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] dax: hide block device code in #ifdef

We allow configurations with CONFIG_BLOCK=n and CONFIG_DAX=y, which now
results in a link error:

drivers/dax/super.c: In function 'bdev_dax_pgoff':
drivers/dax/super.c:50:26: error: implicit declaration of function 'get_start_sect'; did you mean 'get_task_cred'? [-Werror=implicit-function-declaration]

The two obvious ways to avoid the link error are to either add an #ifdef
around the code that was moved from fs/block_dev.c, or to disallow the
configuration. I could not see if there is or is not a reason to support
this combination of options, but in case there is, the #ifdef is the
safer choice.

Fixes: ef51042472f5 ("block, dax: move "select DAX" from BLOCK to FS_DAX")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/dax/super.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index ebf43f531ada..6ed32aac8bbe 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -44,6 +44,7 @@ void dax_read_unlock(int id)
 }
 EXPORT_SYMBOL_GPL(dax_read_unlock);

+#ifdef CONFIG_BLOCK
 int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
 		pgoff_t *pgoff)
 {
@@ -112,6 +113,7 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(__bdev_dax_supported);
+#endif

 /**
  * struct dax_device - anchor object for dax services
-- 
2.9.0