Re: [PATCH] bcachefs: initialize local variables in bch2_evacuate_bucket

[Nathan Chancellor]

On Sun, Nov 17, 2024 at 11:48:23PM +0000, Piotr Zalewski wrote:
> Compiling bcachefs sources with LLVM triggers uninitialized variables
> warnings.
> 
> Signed-off-by: Piotr Zalewski <pz010001011...@proton.me>
> ---
>  fs/bcachefs/move.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/bcachefs/move.c b/fs/bcachefs/move.c
> index 8c032ef3a567..94cac498d372 100644
> --- a/fs/bcachefs/move.c
> +++ b/fs/bcachefs/move.c
> @@ -674,8 +674,8 @@ int bch2_evacuate_bucket(struct moving_context *ctxt,
>       struct bkey_buf sk;
>       struct bkey_s_c k;
>       struct data_update_opts data_opts;
> -     unsigned dirty_sectors, bucket_size;
> -     u64 fragmentation;
> +     unsigned dirty_sectors = 0, bucket_size = 0;
> +     u64 fragmentation = 0;

Shouldn't these just be removed altogether...? They are only used in a
trace event and now only zero.

$ rg 'dirty_sectors|bucket_size|fragmentation' fs/bcachefs/move.c
677:    unsigned dirty_sectors, bucket_size;
678:    u64 fragmentation;
814:    trace_evacuate_bucket(c, &bucket, dirty_sectors, bucket_size, 
fragmentation, ret);

Something like below seems to compile.

Cheers,
Nathan

diff --git a/fs/bcachefs/move.c b/fs/bcachefs/move.c
index 88ab9d7e1a1b..412ef9897361 100644
--- a/fs/bcachefs/move.c
+++ b/fs/bcachefs/move.c
@@ -674,8 +674,6 @@ int bch2_evacuate_bucket(struct moving_context *ctxt,
        struct bkey_buf sk;
        struct bkey_s_c k;
        struct data_update_opts data_opts;
-       unsigned dirty_sectors, bucket_size;
-       u64 fragmentation;
        int ret = 0;
 
        struct bch_dev *ca = bch2_dev_tryget(c, bucket.inode);
@@ -811,7 +809,7 @@ int bch2_evacuate_bucket(struct moving_context *ctxt,
                bch2_btree_iter_advance(&bp_iter);
        }
 
-       trace_evacuate_bucket(c, &bucket, dirty_sectors, bucket_size, 
fragmentation, ret);
+       trace_evacuate_bucket(c, &bucket, ret);
 err:
        bch2_trans_iter_exit(trans, &bp_iter);
        bch2_dev_put(ca);
diff --git a/fs/bcachefs/trace.h b/fs/bcachefs/trace.h
index 5597b9d6297f..f67914367acf 100644
--- a/fs/bcachefs/trace.h
+++ b/fs/bcachefs/trace.h
@@ -846,18 +846,13 @@ TRACE_EVENT(move_data,
 );
 
 TRACE_EVENT(evacuate_bucket,
-       TP_PROTO(struct bch_fs *c, struct bpos *bucket,
-                unsigned sectors, unsigned bucket_size,
-                u64 fragmentation, int ret),
-       TP_ARGS(c, bucket, sectors, bucket_size, fragmentation, ret),
+       TP_PROTO(struct bch_fs *c, struct bpos *bucket, int ret),
+       TP_ARGS(c, bucket, ret),
 
        TP_STRUCT__entry(
                __field(dev_t,          dev             )
                __field(u64,            member          )
                __field(u64,            bucket          )
-               __field(u32,            sectors         )
-               __field(u32,            bucket_size     )
-               __field(u64,            fragmentation   )
                __field(int,            ret             )
        ),
 
@@ -865,17 +860,12 @@ TRACE_EVENT(evacuate_bucket,
                __entry->dev                    = c->dev;
                __entry->member                 = bucket->inode;
                __entry->bucket                 = bucket->offset;
-               __entry->sectors                = sectors;
-               __entry->bucket_size            = bucket_size;
-               __entry->fragmentation          = fragmentation;
                __entry->ret                    = ret;
        ),
 
-       TP_printk("%d,%d %llu:%llu sectors %u/%u fragmentation %llu ret %i",
+       TP_printk("%d,%d %llu:%llu ret %i",
                  MAJOR(__entry->dev), MINOR(__entry->dev),
-                 __entry->member, __entry->bucket,
-                 __entry->sectors, __entry->bucket_size,
-                 __entry->fragmentation, __entry->ret)
+                 __entry->member, __entry->bucket, __entry->ret)
 );
 
 TRACE_EVENT(copygc,