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SubjectRe: [PATCH 07/16] GFS2: Directory handling

>> > >+static inline int __gfs2_dirent_find(const struct gfs2_dirent *dent,
>> > >+ const struct qstr *name, int ret)
>> > >+{
>> > >+ if (dent->de_inum.no_addr != 0 &&
>> > >+ be32_to_cpu(dent->de_hash) == name->hash &&
>> > >+ be16_to_cpu(dent->de_name_len) == name->len &&
>> > >+ memcmp((char *)(dent+1), name->name, name->len) == 0)
>> >
>> > Nocast.
>> >
>> ok
>
>actually, sizeof(*dent) != 1, so how can a non-casted memcmp be correct
>here?

There is an implicit reinterpret_cast<> from char* to void* when using
memcmp, because void* is what memcpy takes as first argument. So, in effect
we are doing

memcmp((void *)(char *)(dent + 1), ...)

and that cast is, in this case, redundant, meaning we can do

memcmp((void *)(dent + 1), ...)

But since conversion from and to void* is implicit in C, we can do

memcmp(dent + 1, ...)


>> > >+ if ((char *)cur + cur_rec_len >= bh_end) {
>> > >+ if ((char *)cur + cur_rec_len > bh_end) {
>> > >+ gfs2_consist_inode(dip);
>> > >+ return -EIO;
>> > >+ }
>> > >+ return -ENOENT;
>> > >+ }
>> >
>> > if((char *)cur + cur_rec_len > bh_end) {
>> > gfs2_consist_inode(dip);
>> > return -EIO;
>> > } else if((char *)cur + cur_rec_len == bh_end)
>> > return -ENOENT;
>> >
>> ok
>
>this one is not OK! Firstly, Jan, and i mentioned this before, please
>stop using 'if(', it is highly inconsistent and against basic taste. We
>only use this construct for function calls (and macros), not for C
>statements.

Now there is no rule in CodingStyle for this yet. Plus, I was wanting to show
how to reorder the construct, so change in whitespace between "if" and "(" is
outoftopic.

11:17 gwdg-wb04A:~/linux > grep -Pri '(if|for|while)\(' . | wc -l
24242

[To be honest, I also present the other number:]
11:17 gwdg-wb04A:~/linux > grep -Pri '(if|for|while) \(' . | wc -l
380895

Although a minority, it does not seem so uncommon.



>Secondly, whenever we have curly braces in the first block, we tend to
>do it in the second block too, for easier parsing. I.e.:
>
> if ((char *)cur + cur_rec_len > bh_end) {
> gfs2_consist_inode(dip);
> return -EIO;
> } else {
> if ((char *)cur + cur_rec_len == bh_end)
> return -ENOENT;
> }

I would very much like to do just this

many insns;
} else if(...) {
single insn;
}

but again, some people think no {} should be there because it's just a single
insn. Though I don't go harvesting in lkml.org archives right now to prove
this claim.



>Thirdly, the original code was quite fine as-is! What's the point of
>introducing random perturbations like this? It is an open invitation for
>the introduction of bugs... So unless there is a clear style reason to
>do a change, i'd suggest to not touch the code.

Intent was reduction of indent. ""The answer to that is that if you need
more than 3 levels of indentation, you're screwed anyway, and should fix
your program."" so says CodingStyle, though the 3-level barrier was only
touched this time.

No offense!



Jan Engelhardt
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