Re: [PATCH 5.15] udf: Allocate name buffer in directory iterator on heap

[Sasha Levin]

On Wed, Nov 13, 2024 at 01:30:35PM +0900, Sergey Senozhatsky wrote:
> From: Jan Kara <jack@xxxxxxx>
>
> [ Upstream commit 0aba4860b0d0216a1a300484ff536171894d49d8 ]
>
> Currently we allocate name buffer in directory iterators (struct
> udf_fileident_iter) on stack. These structures are relatively large
> (some 360 bytes on 64-bit architectures). For udf_rename() which needs
> to keep three of these structures in parallel the stack usage becomes
> rather heavy - 1536 bytes in total. Allocate the name buffer in the
> iterator from heap to avoid excessive stack usage.
>
> Link: https://lore.kernel.org/all/202212200558.lK9x1KW0-lkp@xxxxxxxxx
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Signed-off-by: Jan Kara <jack@xxxxxxx>

Your S-O-B is missing, but also it doesn't build:

fs/udf/directory.c: In function 'udf_fiiter_init':
fs/udf/directory.c:251:25: error: implicit declaration of function 'kmalloc'; did you mean 'kvmalloc'? [-Werror=implicit-function-declaration]
  251 |         iter->namebuf = kmalloc(UDF_NAME_LEN_CS0, GFP_KERNEL);
      |                         ^~~~~~~
      |                         kvmalloc
fs/udf/directory.c:251:23: warning: assignment to 'uint8_t *' {aka 'unsigned char *'} from 'int' makes pointer from integer without a cast [-Wint-conversion]
  251 |         iter->namebuf = kmalloc(UDF_NAME_LEN_CS0, GFP_KERNEL);
      |                       ^
fs/udf/directory.c: In function 'udf_fiiter_release':
fs/udf/directory.c:315:9: error: implicit declaration of function 'kfree'; did you mean 'kvfree'? [-Werror=implicit-function-declaration]
  315 |         kfree(iter->namebuf);
      |         ^~~~~
      |         kvfree

--
Thanks,
Sasha