On Wed, Jan 11, 2023 at 03:43:27PM +0100, Jan Kara wrote:
> On Fri 16-12-22 21:02:12, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@xxxxxxxxxx>
> >
> > To avoid 'sparse' warnings about missing endianness conversions, don't
> > store native endianness values into struct ext4_fc_tl. Instead, use a
> > separate struct type, ext4_fc_tl_mem.
> >
> > Fixes: dcc5827484d6 ("ext4: factor out ext4_fc_get_tl()")
> > Cc: Ye Bin <yebin10@xxxxxxxxxx>
> > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> Looks good to me. Just one nit below:
>
> > -static inline void ext4_fc_get_tl(struct ext4_fc_tl *tl, u8 *val)
> > +static inline void ext4_fc_get_tl(struct ext4_fc_tl_mem *tl, u8 *val)
> > {
> > - memcpy(tl, val, EXT4_FC_TAG_BASE_LEN);
> > - tl->fc_len = le16_to_cpu(tl->fc_len);
> > - tl->fc_tag = le16_to_cpu(tl->fc_tag);
> > + struct ext4_fc_tl tl_disk;
> > +
> > + memcpy(&tl_disk, val, EXT4_FC_TAG_BASE_LEN);
> > + tl->fc_len = le16_to_cpu(tl_disk.fc_len);
> > + tl->fc_tag = le16_to_cpu(tl_disk.fc_tag);
> > }
>
> So why not just:
>
> struct ext4_fc_tl *tl_disk = (struct ext4_fc_tl *)val;
>
> instead of memcpy?
That would result in unaligned memory accesses.
- Eric
