[PATCH] 9p: fix unused-variable warning

[PATCH] 9p: fix unused-variable warning

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The folio changes added a variable that is sometimes unused:

fs/9p/vfs_addr.c: In function 'v9fs_release_page':
fs/9p/vfs_addr.c:140:23: error: unused variable 'inode' [-Werror=unused-variable]
  140 |         struct inode *inode = folio_inode(folio);
      |                       ^~~~~

Make this clearer to the compiler by replacing the #ifdef
with an equivalent if(IS_ENABLED()) check.

Fixes: 78525c74d9e7 ("netfs, 9p, afs, ceph: Use folios")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 fs/9p/vfs_addr.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 1279970e9157..82ac2ceff06e 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -141,14 +141,17 @@ static int v9fs_release_page(struct page *page, gfp_t gfp)
 
 	if (folio_test_private(folio))
 		return 0;
-#ifdef CONFIG_9P_FSCACHE
+
+	if (!IS_ENABLED(CONFIG_9P_FSCACHE))
+		return 1;
+
 	if (folio_test_fscache(folio)) {
 		if (!(gfp & __GFP_DIRECT_RECLAIM) || !(gfp & __GFP_FS))
 			return 0;
 		folio_wait_fscache(folio);
 	}
 	fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode)));
-#endif
+
 	return 1;
 }
 
-- 
2.29.2

Re: [PATCH] 9p: fix unused-variable warning

[Dominique Martinet]

Dominique Martinet wrote on Sat, Dec 04, 2021 at 09:04:04AM +0900:
> Arnd Bergmann wrote on Fri, Dec 03, 2021 at 07:58:06PM +0100:
> > From: Arnd Bergmann <arnd@arndb.de>
> > 
> > The folio changes added a variable that is sometimes unused:
> > 
> > fs/9p/vfs_addr.c: In function 'v9fs_release_page':
> > fs/9p/vfs_addr.c:140:23: error: unused variable 'inode' [-Werror=unused-variable]
> >   140 |         struct inode *inode = folio_inode(folio);
> >       |                       ^~~~~
> > 
> > Make this clearer to the compiler by replacing the #ifdef
> > with an equivalent if(IS_ENABLED()) check.
> > 
> > Fixes: 78525c74d9e7 ("netfs, 9p, afs, ceph: Use folios")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> 
> Looks good to me, picking it up

Sorry it took me a while to actually do the picking up part, but this
appears to have been a patch for linux-next back then and I didn't
notice because the Fixes tag is incorrect (78525c74d9e7 didn't introduce
the inode variable, it actually fixes a patch that never has been merged)

David since then fixed the warning differently in v2 of the patch (he
moved the fscache_note_page_release() out of the ifdef), so I won't do
anything with this even if in principle I tend to agree that
if(IS_ENABLED()) lead to better compiler coverage

Thanks though!
-- 
Dominique

Re: [PATCH] 9p: fix unused-variable warning

[David Howells]

Dominique Martinet <asmadeus@codewreck.org> wrote:

> David since then fixed the warning differently in v2 of the patch (he
> moved the fscache_note_page_release() out of the ifdef), so I won't do
> anything with this even if in principle I tend to agree that
> if(IS_ENABLED()) lead to better compiler coverage

Yeah, fscache_note_page_release() compiles out in such a case because
v9fs_inode_cookie() becomes unconditionally NULL if it's disabled.

If you want me to do something different, can you give me an incremental patch
to merge into mine?

David