[PATCH] logfs: fix build warning

[PATCH] logfs: fix build warning

[Sudip Mukherjee]

While building we were getting build warning of:

fs/logfs/dev_bdev.c: In function '__bdev_writeseg':
include/linux/kernel.h:601:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
  (void) (&_min1 == &_min2);  \
fs/logfs/dev_bdev.c:84:14: note: in  expansion of macro 'min'
  max_pages = min(nr_pages, BIO_MAX_PAGES);

fs/logfs/dev_bdev.c: In function 'do_erase':
include/linux/kernel.h:601:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
 (void) (&_min1 == &_min2);  \
fs/logfs/dev_bdev.c:174:14: note: in expansion of macro 'min'
 max_pages = min(nr_pages, BIO_MAX_PAGES);

Lets use min_t and mention the type.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
---
 fs/logfs/dev_bdev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/logfs/dev_bdev.c b/fs/logfs/dev_bdev.c
index a7fdbd8..a709d80 100644
--- a/fs/logfs/dev_bdev.c
+++ b/fs/logfs/dev_bdev.c
@@ -81,7 +81,7 @@ static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
 	unsigned int max_pages;
 	int i;
 
-	max_pages = min(nr_pages, BIO_MAX_PAGES);
+	max_pages = min_t(size_t, nr_pages, BIO_MAX_PAGES);
 
 	bio = bio_alloc(GFP_NOFS, max_pages);
 	BUG_ON(!bio);
@@ -171,7 +171,7 @@ static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index,
 	unsigned int max_pages;
 	int i;
 
-	max_pages = min(nr_pages, BIO_MAX_PAGES);
+	max_pages = min_t(size_t, nr_pages, BIO_MAX_PAGES);
 
 	bio = bio_alloc(GFP_NOFS, max_pages);
 	BUG_ON(!bio);
-- 
1.9.1

Re: [PATCH] logfs: fix build warning

[Sudip Mukherjee]

On Thu, Sep 10, 2015 at 03:41:04PM +0530, Sudip Mukherjee wrote:
> While building we were getting build warning of:
> 
> fs/logfs/dev_bdev.c: In function '__bdev_writeseg':
> include/linux/kernel.h:601:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
>   (void) (&_min1 == &_min2);  \
> fs/logfs/dev_bdev.c:84:14: note: in  expansion of macro 'min'
>   max_pages = min(nr_pages, BIO_MAX_PAGES);
> 
> fs/logfs/dev_bdev.c: In function 'do_erase':
> include/linux/kernel.h:601:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
>  (void) (&_min1 == &_min2);  \
> fs/logfs/dev_bdev.c:174:14: note: in expansion of macro 'min'
>  max_pages = min(nr_pages, BIO_MAX_PAGES);
> 
> Lets use min_t and mention the type.
> 
> Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
> ---
Hi,
I know its too early to ping. But I can still see the build warnings
with i386 allmodconfig. Build is at:
https://travis-ci.org/sudipm-mukherjee/parport/jobs/80365417

regards
sudip

Re: [PATCH] logfs: fix build warning

[Sudip Mukherjee]

On Tue, Sep 15, 2015 at 01:33:15PM +0530, Sudip Mukherjee wrote:
> On Thu, Sep 10, 2015 at 03:41:04PM +0530, Sudip Mukherjee wrote:
> > While building we were getting build warning of:
> > 
> > fs/logfs/dev_bdev.c: In function '__bdev_writeseg':
> > include/linux/kernel.h:601:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
> >   (void) (&_min1 == &_min2);  \
> > fs/logfs/dev_bdev.c:84:14: note: in  expansion of macro 'min'
> >   max_pages = min(nr_pages, BIO_MAX_PAGES);
> > 
> > fs/logfs/dev_bdev.c: In function 'do_erase':
> > include/linux/kernel.h:601:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
> >  (void) (&_min1 == &_min2);  \
> > fs/logfs/dev_bdev.c:174:14: note: in expansion of macro 'min'
> >  max_pages = min(nr_pages, BIO_MAX_PAGES);
> > 
> > Lets use min_t and mention the type.
> > 
> > Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
> > ---
> Hi,
> I know its too early to ping. But I can still see the build warnings
> with i386 allmodconfig. Build is at:
> https://travis-ci.org/sudipm-mukherjee/parport/jobs/80365417
Another gentle ping. Build warning still shows with next-20150929.

regards
sudip

Re: [PATCH] logfs: fix build warning

[Andrew Morton]

On Thu, 10 Sep 2015 15:41:04 +0530 Sudip Mukherjee <sudipm.mukherjee@gmail.com> wrote:

> While building we were getting build warning of:
> 
> fs/logfs/dev_bdev.c: In function '__bdev_writeseg':
> include/linux/kernel.h:601:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
>   (void) (&_min1 == &_min2);  \
> fs/logfs/dev_bdev.c:84:14: note: in  expansion of macro 'min'
>   max_pages = min(nr_pages, BIO_MAX_PAGES);
> 
> fs/logfs/dev_bdev.c: In function 'do_erase':
> include/linux/kernel.h:601:17: warning: comparison of distinct pointer types lacks a cast [enabled by default]
>  (void) (&_min1 == &_min2);  \
> fs/logfs/dev_bdev.c:174:14: note: in expansion of macro 'min'
>  max_pages = min(nr_pages, BIO_MAX_PAGES);
> 
> Lets use min_t and mention the type.
> 
> ...
>
> --- a/fs/logfs/dev_bdev.c
> +++ b/fs/logfs/dev_bdev.c
> @@ -81,7 +81,7 @@ static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
>  	unsigned int max_pages;
>  	int i;
>  
> -	max_pages = min(nr_pages, BIO_MAX_PAGES);
> +	max_pages = min_t(size_t, nr_pages, BIO_MAX_PAGES);
>  
>  	bio = bio_alloc(GFP_NOFS, max_pages);
>  	BUG_ON(!bio);
> @@ -171,7 +171,7 @@ static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index,
>  	unsigned int max_pages;
>  	int i;
>  
> -	max_pages = min(nr_pages, BIO_MAX_PAGES);
> +	max_pages = min_t(size_t, nr_pages, BIO_MAX_PAGES);
>  
>  	bio = bio_alloc(GFP_NOFS, max_pages);
>  	BUG_ON(!bio);

I don't think it's logical for either __bdev_writeseg() or do_erase()
to use size_t for `nr_pages'.  For "number of pagecache pages" we'd
normally use pgoff_t or unsigned long.

But they'd generate warnings as well, because BIO_MAX_PAGES is plain
old `int'.  Ho hum.