On Sat, Oct 20, 2018 at 11:09:57PM +0100, Phillip Potter wrote:
> Remove switch statement from ufs_set_de_type function in fs/ufs/util.h
> header and replace with simple assignment. For each case, S_IFx >> 12
> is equal to DT_x, so in valid cases (mode & S_IFMT) >> 12 should give
> us the correct file type. It is expected that for *nix compatibility
> reasons, the relation between S_IFx and DT_x will not change. For
> cases where the mode is invalid, upper layer validation catches this
> anyway, so this improves readability and arguably performance by
> assigning (mode & S_IFMT) >> 12 directly without any jump table
> or conditional logic.
Shouldn't we also do this for other filesystems? A quick scan suggests
someone should at least look at xfs, ubifs, squashfs, romfs, ocfs2,
nilfs2, hfsplus, f2fs, ext4, ext2, exofs, coda, cifs & btrfs.
> Signed-off-by: Phillip Potter <phil@xxxxxxxxxxxxxxxx>
> ---
> fs/ufs/util.h | 30 ++----------------------------
> 1 file changed, 2 insertions(+), 28 deletions(-)
>
> diff --git a/fs/ufs/util.h b/fs/ufs/util.h
> index 1fd3011ea623..7e0c0878b9f9 100644
> --- a/fs/ufs/util.h
> +++ b/fs/ufs/util.h
> @@ -16,6 +16,7 @@
> * some useful macros
> */
> #define in_range(b,first,len) ((b)>=(first)&&(b)<(first)+(len))
> +#define S_SHIFT 12
>
> /*
> * functions used for retyping
> @@ -158,34 +159,7 @@ ufs_set_de_type(struct super_block *sb, struct ufs_dir_entry *de, int mode)
> if ((UFS_SB(sb)->s_flags & UFS_DE_MASK) != UFS_DE_44BSD)
> return;
>
> - /*
> - * TODO turn this into a table lookup
> - */
> - switch (mode & S_IFMT) {
> - case S_IFSOCK:
> - de->d_u.d_44.d_type = DT_SOCK;
> - break;
> - case S_IFLNK:
> - de->d_u.d_44.d_type = DT_LNK;
> - break;
> - case S_IFREG:
> - de->d_u.d_44.d_type = DT_REG;
> - break;
> - case S_IFBLK:
> - de->d_u.d_44.d_type = DT_BLK;
> - break;
> - case S_IFDIR:
> - de->d_u.d_44.d_type = DT_DIR;
> - break;
> - case S_IFCHR:
> - de->d_u.d_44.d_type = DT_CHR;
> - break;
> - case S_IFIFO:
> - de->d_u.d_44.d_type = DT_FIFO;
> - break;
> - default:
> - de->d_u.d_44.d_type = DT_UNKNOWN;
> - }
> + de->d_u.d_44.d_type = (mode & S_IFMT) >> S_SHIFT;
> }
>
> static inline u32
> --
> 2.17.2
>
