[PATCH] btrfs: send: Silence build warning about kvcalloc()

[PATCH] btrfs: send: Silence build warning about kvcalloc()

[Tiezhu Yang]

There exist the following warning when building kernel v6.7:

  CC      fs/btrfs/send.o
fs/btrfs/send.c: In function ‘btrfs_ioctl_send’:
fs/btrfs/send.c:8208:44: warning: ‘kvcalloc’ sizes specified with ‘sizeof’ in the earlier argument and not in the later argument [-Wcalloc-transposed-args]
 8208 |         sctx->clone_roots = kvcalloc(sizeof(*sctx->clone_roots),
      |                                            ^
fs/btrfs/send.c:8208:44: note: earlier argument should specify number of elements, later size of each element

tested with the latest upstream toolchains (20240105):

  [fedora@linux 6.7.test]$ gcc --version
  gcc (GCC) 14.0.0 20240105 (experimental)
  [fedora@linux 6.7.test]$ as --version
  GNU assembler (GNU Binutils) 2.41.50.20240105
  [fedora@linux 6.7.test]$ ld --version
  GNU ld (GNU Binutils) 2.41.50.20240105

just switch the first and second arguments of kvcalloc() to silence
the build warning, compile tested only.

Fixes: bae12df966f0 ("btrfs: use kvcalloc for allocation in btrfs_ioctl_send()")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 fs/btrfs/send.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 4e36550618e5..2d7519a6ce72 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -8205,8 +8205,8 @@ long btrfs_ioctl_send(struct inode *inode, struct btrfs_ioctl_send_args *arg)
 		goto out;
 	}
 
-	sctx->clone_roots = kvcalloc(sizeof(*sctx->clone_roots),
-				     arg->clone_sources_count + 1,
+	sctx->clone_roots = kvcalloc(arg->clone_sources_count + 1,
+				     sizeof(*sctx->clone_roots),
 				     GFP_KERNEL);
 	if (!sctx->clone_roots) {
 		ret = -ENOMEM;
-- 
2.42.0

Re: [PATCH] btrfs: send: Silence build warning about kvcalloc()

[David Sterba]

On Mon, Jan 08, 2024 at 12:13:51PM +0800, Tiezhu Yang wrote:
> There exist the following warning when building kernel v6.7:
> 
>   CC      fs/btrfs/send.o
> fs/btrfs/send.c: In function ‘btrfs_ioctl_send’:
> fs/btrfs/send.c:8208:44: warning: ‘kvcalloc’ sizes specified with ‘sizeof’ in the earlier argument and not in the later argument [-Wcalloc-transposed-args]
>  8208 |         sctx->clone_roots = kvcalloc(sizeof(*sctx->clone_roots),
>       |                                            ^
> fs/btrfs/send.c:8208:44: note: earlier argument should specify number of elements, later size of each element
> 
> tested with the latest upstream toolchains (20240105):
> 
>   [fedora@linux 6.7.test]$ gcc --version
>   gcc (GCC) 14.0.0 20240105 (experimental)
>   [fedora@linux 6.7.test]$ as --version
>   GNU assembler (GNU Binutils) 2.41.50.20240105
>   [fedora@linux 6.7.test]$ ld --version
>   GNU ld (GNU Binutils) 2.41.50.20240105
> 
> just switch the first and second arguments of kvcalloc() to silence
> the build warning, compile tested only.
> 
> Fixes: bae12df966f0 ("btrfs: use kvcalloc for allocation in btrfs_ioctl_send()")
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>

Thanks, a fix has been already sent
https://lore.kernel.org/linux-btrfs/20231221084748.10094-1-dmantipov@yandex.ru/