lkml.org 
[lkml]   [2016]   [Jul]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/4] fs: befs: Remove redundant validation from befs_find_brun_direct
On Sat, Jul 02, 2016 at 12:38:18PM +0100, Luis de Bethencourt wrote:
> On 02/07/16 09:05, Salah Triki wrote:
> > The only caller of befs_find_brun_direct is befs_fblock2brun, which
> > already validates that the block is within the range of direct blocks.
> > So remove the duplicate validation.
> >
> > Signed-off-by: Salah Triki <salah.triki@gmail.com>
> > ---
> > fs/befs/datastream.c | 8 --------
> > 1 file changed, 8 deletions(-)
> >
> > diff --git a/fs/befs/datastream.c b/fs/befs/datastream.c
> > index 26cc417..e224b9a 100644
> > --- a/fs/befs/datastream.c
> > +++ b/fs/befs/datastream.c
> > @@ -249,17 +249,9 @@ befs_find_brun_direct(struct super_block *sb, const befs_data_stream *data,
> > int i;
> > const befs_block_run *array = data->direct;
> > befs_blocknr_t sum;
> > - befs_blocknr_t max_block =
> > - data->max_direct_range >> BEFS_SB(sb)->block_shift;
> >
> > befs_debug(sb, "---> %s, find %lu", __func__, (unsigned long)blockno);
> >
> > - if (blockno > max_block) {
> > - befs_error(sb, "%s passed block outside of direct region",
> > - __func__);
> > - return BEFS_ERR;
> > - }
> > -
> > for (i = 0, sum = 0; i < BEFS_NUM_DIRECT_BLOCKS;
> > sum += array[i].len, i++) {
> > if (blockno >= sum && blockno < sum + (array[i].len)) {
> >
>
> Hi Salah,
>
> These aren't the same check though. If we ignore the BEFS_SB(sb)->block_shift just to
> comparing them, we can consider the checks to be the following.
>
> In befs_fblock2brun():
> if (fblock < data->max_direct_range)
>
> In befs_find_brun_direct():
> if (fblock > data->max_direct_range)
>
> Notice how one checks if the block is past the range, and the other checks if it isn't
> before it.
>
> They also looked similar to me the first time I saw them and I had to double-check :)
>
> Thanks,
> Luis
>
>

the two checks could not be evaluated to true at the same time, and since befs_find_brun_direct
is called only when the first check is passed, the second check will be always evaluated to false.
So I think the second check is useless, am I right ?

Salah

\
 
 \ /
  Last update: 2016-07-02 16:41    [W:0.065 / U:9.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site