On Tue, Nov 05, 2024 at 12:06:42PM +0100, Thorsten Blum wrote: > On 5. Nov 2024, at 11:39, Greg KH wrote: > > On Tue, Nov 05, 2024 at 11:33:54AM +0100, Thorsten Blum wrote: > >> Inline and use struct_size() to calculate the number of bytes to > >> allocate for new_fn and remove the local variable len. > >> > >> Reviewed-by: Jan Kara <jack@xxxxxxx> > >> Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxx> > >> --- > >> This change was originally part of another patch that was split into two > >> separate patches after feedback from Greg KH > >> - Link: https://lore.kernel.org/r/20241104234214.8094-2-thorsten.blum@xxxxxxxxx/ > >> --- > >> fs/ext4/dir.c | 5 ++--- > >> 1 file changed, 2 insertions(+), 3 deletions(-) > >> > >> diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c > >> index 233479647f1b..02d47a64e8d1 100644 > >> --- a/fs/ext4/dir.c > >> +++ b/fs/ext4/dir.c > >> @@ -471,14 +471,13 @@ int ext4_htree_store_dirent(struct file *dir_file, __u32 hash, > >> struct rb_node **p, *parent = NULL; > >> struct fname *fname, *new_fn; > >> struct dir_private_info *info; > >> - int len; > >> > >> info = dir_file->private_data; > >> p = &info->root.rb_node; > >> > >> /* Create and allocate the fname structure */ > >> - len = sizeof(struct fname) + ent_name->len + 1; > >> - new_fn = kzalloc(len, GFP_KERNEL); > >> + new_fn = kzalloc(struct_size(new_fn, name, ent_name->len + 1), > >> + GFP_KERNEL); > > > > Does this actually matter and make the code any more robust or faster? > > > > The original code here is easier to read and understand, why add > > complexity if it is not required? > > I find struct_size() to be more readable because it explicitly > communicates the relationship between the flexible array member name and > ent_name->len that the open-coded version doesn't. Plus, struct_size() > has some additional compile-time checks (e.g., __must_be_array()). Ah, missed that, sure, that makes more sense, sorry for the noise. greg k-h
