[PATCH] bcachefs: Use snprintf() instead of scnprintf() when appropriate

[PATCH] bcachefs: Use snprintf() instead of scnprintf() when appropriate

[Christophe JAILLET]

snprintf() and scnprintf() are the same, except for the returned value.
When this value is not used, it is more logical to use snprintf() which is
slightly simpler.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 fs/bcachefs/super.c | 2 +-
 fs/bcachefs/tests.c | 2 +-
 fs/bcachefs/trace.h | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 2990eed85adf..773ea93e44c1 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1180,7 +1180,7 @@ static void bch2_dev_attach(struct bch_fs *c, struct bch_dev *ca,
 {
 	ca->dev_idx = dev_idx;
 	__set_bit(ca->dev_idx, ca->self.d);
-	scnprintf(ca->name, sizeof(ca->name), "dev-%u", dev_idx);
+	snprintf(ca->name, sizeof(ca->name), "dev-%u", dev_idx);
 
 	ca->fs = c;
 	rcu_assign_pointer(c->devs[ca->dev_idx], ca);
diff --git a/fs/bcachefs/tests.c b/fs/bcachefs/tests.c
index c907b3e00176..72f9bf186f9c 100644
--- a/fs/bcachefs/tests.c
+++ b/fs/bcachefs/tests.c
@@ -926,7 +926,7 @@ int bch2_btree_perf_test(struct bch_fs *c, const char *testname,
 
 	time = j.finish - j.start;
 
-	scnprintf(name_buf, sizeof(name_buf), "%s:", testname);
+	snprintf(name_buf, sizeof(name_buf), "%s:", testname);
 	prt_human_readable_u64(&nr_buf, nr);
 	prt_human_readable_u64(&per_sec_buf, div64_u64(nr * NSEC_PER_SEC, time));
 	printk(KERN_INFO "%-12s %s with %u threads in %5llu sec, %5llu nsec per iter, %5s per sec\n",
diff --git a/fs/bcachefs/trace.h b/fs/bcachefs/trace.h
index 19264492151b..da303dd4b71c 100644
--- a/fs/bcachefs/trace.h
+++ b/fs/bcachefs/trace.h
@@ -450,7 +450,7 @@ TRACE_EVENT(btree_path_relock_fail,
 			c = six_lock_counts(&path->l[level].b->c.lock);
 			__entry->read_count	= c.n[SIX_LOCK_read];
 			__entry->intent_count	= c.n[SIX_LOCK_intent];
-			scnprintf(__entry->node, sizeof(__entry->node), "%px", b);
+			snprintf(__entry->node, sizeof(__entry->node), "%px", b);
 		}
 		__entry->iter_lock_seq		= path->l[level].lock_seq;
 		__entry->node_lock_seq		= is_btree_node(path, level)
-- 
2.34.1

Re: [PATCH] bcachefs: Use snprintf() instead of scnprintf() when appropriate

[Brian Foster]

On Sat, Sep 16, 2023 at 09:30:19AM +0200, Christophe JAILLET wrote:
> snprintf() and scnprintf() are the same, except for the returned value.
> When this value is not used, it is more logical to use snprintf() which is
> slightly simpler.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---

Seems reasonable:

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/bcachefs/super.c | 2 +-
>  fs/bcachefs/tests.c | 2 +-
>  fs/bcachefs/trace.h | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
> index 2990eed85adf..773ea93e44c1 100644
> --- a/fs/bcachefs/super.c
> +++ b/fs/bcachefs/super.c
> @@ -1180,7 +1180,7 @@ static void bch2_dev_attach(struct bch_fs *c, struct bch_dev *ca,
>  {
>  	ca->dev_idx = dev_idx;
>  	__set_bit(ca->dev_idx, ca->self.d);
> -	scnprintf(ca->name, sizeof(ca->name), "dev-%u", dev_idx);
> +	snprintf(ca->name, sizeof(ca->name), "dev-%u", dev_idx);
>  
>  	ca->fs = c;
>  	rcu_assign_pointer(c->devs[ca->dev_idx], ca);
> diff --git a/fs/bcachefs/tests.c b/fs/bcachefs/tests.c
> index c907b3e00176..72f9bf186f9c 100644
> --- a/fs/bcachefs/tests.c
> +++ b/fs/bcachefs/tests.c
> @@ -926,7 +926,7 @@ int bch2_btree_perf_test(struct bch_fs *c, const char *testname,
>  
>  	time = j.finish - j.start;
>  
> -	scnprintf(name_buf, sizeof(name_buf), "%s:", testname);
> +	snprintf(name_buf, sizeof(name_buf), "%s:", testname);
>  	prt_human_readable_u64(&nr_buf, nr);
>  	prt_human_readable_u64(&per_sec_buf, div64_u64(nr * NSEC_PER_SEC, time));
>  	printk(KERN_INFO "%-12s %s with %u threads in %5llu sec, %5llu nsec per iter, %5s per sec\n",
> diff --git a/fs/bcachefs/trace.h b/fs/bcachefs/trace.h
> index 19264492151b..da303dd4b71c 100644
> --- a/fs/bcachefs/trace.h
> +++ b/fs/bcachefs/trace.h
> @@ -450,7 +450,7 @@ TRACE_EVENT(btree_path_relock_fail,
>  			c = six_lock_counts(&path->l[level].b->c.lock);
>  			__entry->read_count	= c.n[SIX_LOCK_read];
>  			__entry->intent_count	= c.n[SIX_LOCK_intent];
> -			scnprintf(__entry->node, sizeof(__entry->node), "%px", b);
> +			snprintf(__entry->node, sizeof(__entry->node), "%px", b);
>  		}
>  		__entry->iter_lock_seq		= path->l[level].lock_seq;
>  		__entry->node_lock_seq		= is_btree_node(path, level)
> -- 
> 2.34.1
> 

Re: [PATCH] bcachefs: Use snprintf() instead of scnprintf() when appropriate

[Kent Overstreet]

On Tue, Sep 19, 2023 at 09:17:27AM -0400, Brian Foster wrote:
> On Sat, Sep 16, 2023 at 09:30:19AM +0200, Christophe JAILLET wrote:
> > snprintf() and scnprintf() are the same, except for the returned value.
> > When this value is not used, it is more logical to use snprintf() which is
> > slightly simpler.
> > 
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> > ---
> 
> Seems reasonable:
> 
> Reviewed-by: Brian Foster <bfoster@redhat.com>

No, let's stay with scnprintf as the default - snprintf should be
deprecated except for when its return value is actually needed, using it
incorrectly has been a source of buffer overruns in the past.

Re: [PATCH] bcachefs: Use snprintf() instead of scnprintf() when appropriate

[Christophe JAILLET]

Le 19/09/2023 à 21:02, Kent Overstreet a écrit :
> On Tue, Sep 19, 2023 at 09:17:27AM -0400, Brian Foster wrote:
>> On Sat, Sep 16, 2023 at 09:30:19AM +0200, Christophe JAILLET wrote:
>>> snprintf() and scnprintf() are the same, except for the returned value.
>>> When this value is not used, it is more logical to use snprintf() which is
>>> slightly simpler.
>>>
>>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
>>> ---
>>
>> Seems reasonable:
>>
>> Reviewed-by: Brian Foster <bfoster@redhat.com>
> 
> No, let's stay with scnprintf as the default - snprintf should be
> deprecated except for when its return value is actually needed, using it
> incorrectly has been a source of buffer overruns in the past.
> 

Ok, I was not aware of it.

In this case, there are also some s/snprintf/scnprintf/ opportunities in 
fs/bcachefs

Does it make sense to update them or is it too low value changes?

CJ

Re: [PATCH] bcachefs: Use snprintf() instead of scnprintf() when appropriate

[Kent Overstreet]

On Tue, Sep 19, 2023 at 09:23:47PM +0200, Christophe JAILLET wrote:
> Le 19/09/2023 à 21:02, Kent Overstreet a écrit :
> > On Tue, Sep 19, 2023 at 09:17:27AM -0400, Brian Foster wrote:
> > > On Sat, Sep 16, 2023 at 09:30:19AM +0200, Christophe JAILLET wrote:
> > > > snprintf() and scnprintf() are the same, except for the returned value.
> > > > When this value is not used, it is more logical to use snprintf() which is
> > > > slightly simpler.
> > > > 
> > > > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> > > > ---
> > > 
> > > Seems reasonable:
> > > 
> > > Reviewed-by: Brian Foster <bfoster@redhat.com>
> > 
> > No, let's stay with scnprintf as the default - snprintf should be
> > deprecated except for when its return value is actually needed, using it
> > incorrectly has been a source of buffer overruns in the past.
> > 
> 
> Ok, I was not aware of it.
> 
> In this case, there are also some s/snprintf/scnprintf/ opportunities in
> fs/bcachefs
> 
> Does it make sense to update them or is it too low value changes?

Not terribly important - long term, I want to depracate both snprintf
and scnprintf and convert everything to printbufs.