[PATCH 1/4] f2fs: limit b_size of mapped bh in f2fs_map_bh

[PATCH 1/4] f2fs: limit b_size of mapped bh in f2fs_map_bh

[Chao Yu]

Map bh over max size which caller defined is not needed, limit it in
f2fs_map_bh.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
---
 fs/f2fs/data.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index f0a18a0..a99bc7f 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -255,15 +255,16 @@ static void f2fs_map_bh(struct super_block *sb, pgoff_t pgofs,
 			struct extent_info *ei, struct buffer_head *bh_result)
 {
 	unsigned int blkbits = sb->s_blocksize_bits;
+	unsigned int maxblocks = bh_result->b_size >> blkbits;
 	size_t count;
 
 	clear_buffer_new(bh_result);
 	map_bh(bh_result, sb, ei->blk + pgofs - ei->fofs);
 	count = ei->fofs + ei->len - pgofs;
-	if (count < (UINT_MAX >> blkbits))
-		bh_result->b_size = (count << blkbits);
+	if (count > maxblocks)
+		bh_result->b_size = maxblocks << blkbits;
 	else
-		bh_result->b_size = UINT_MAX;
+		bh_result->b_size = count << blkbits;
 }
 
 static bool lookup_extent_info(struct inode *inode, pgoff_t pgofs,
-- 
2.3.3

Re: [PATCH 1/4] f2fs: limit b_size of mapped bh in f2fs_map_bh

[Jaegeuk Kim]

Hi Chao,

On Mon, Mar 23, 2015 at 10:28:00AM +0800, Chao Yu wrote:
> Map bh over max size which caller defined is not needed, limit it in
> f2fs_map_bh.
> 
> Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> ---
>  fs/f2fs/data.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index f0a18a0..a99bc7f 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -255,15 +255,16 @@ static void f2fs_map_bh(struct super_block *sb, pgoff_t pgofs,
>  			struct extent_info *ei, struct buffer_head *bh_result)
>  {
>  	unsigned int blkbits = sb->s_blocksize_bits;
> +	unsigned int maxblocks = bh_result->b_size >> blkbits;
>  	size_t count;
>  
>  	clear_buffer_new(bh_result);
>  	map_bh(bh_result, sb, ei->blk + pgofs - ei->fofs);
>  	count = ei->fofs + ei->len - pgofs;
> -	if (count < (UINT_MAX >> blkbits))
> -		bh_result->b_size = (count << blkbits);
> +	if (count > maxblocks)
> +		bh_result->b_size = maxblocks << blkbits;
>  	else
> -		bh_result->b_size = UINT_MAX;
> +		bh_result->b_size = count << blkbits;

How about using min()?

Thanks,

>  }
>  
>  static bool lookup_extent_info(struct inode *inode, pgoff_t pgofs,
> -- 
> 2.3.3

RE: [PATCH 1/4] f2fs: limit b_size of mapped bh in f2fs_map_bh

[Chao Yu]

Hi Jaegeuk,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@kernel.org]
> Sent: Tuesday, March 24, 2015 12:42 PM
> To: Chao Yu
> Cc: Changman Lee; linux-f2fs-devel@lists.sourceforge.net; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH 1/4] f2fs: limit b_size of mapped bh in f2fs_map_bh
> 
> Hi Chao,
> 
> On Mon, Mar 23, 2015 at 10:28:00AM +0800, Chao Yu wrote:
> > Map bh over max size which caller defined is not needed, limit it in
> > f2fs_map_bh.
> >
> > Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> > ---
> >  fs/f2fs/data.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index f0a18a0..a99bc7f 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -255,15 +255,16 @@ static void f2fs_map_bh(struct super_block *sb, pgoff_t pgofs,
> >  			struct extent_info *ei, struct buffer_head *bh_result)
> >  {
> >  	unsigned int blkbits = sb->s_blocksize_bits;
> > +	unsigned int maxblocks = bh_result->b_size >> blkbits;
> >  	size_t count;
> >
> >  	clear_buffer_new(bh_result);
> >  	map_bh(bh_result, sb, ei->blk + pgofs - ei->fofs);
> >  	count = ei->fofs + ei->len - pgofs;
> > -	if (count < (UINT_MAX >> blkbits))
> > -		bh_result->b_size = (count << blkbits);
> > +	if (count > maxblocks)
> > +		bh_result->b_size = maxblocks << blkbits;
> >  	else
> > -		bh_result->b_size = UINT_MAX;
> > +		bh_result->b_size = count << blkbits;
> 
> How about using min()?

Better, I will do it. :)

Thanks,

> 
> Thanks,
> 
> >  }
> >
> >  static bool lookup_extent_info(struct inode *inode, pgoff_t pgofs,
> > --
> > 2.3.3