Re: [PATCH] fs/dcache: Re-use value stored to dentry->d_flags instead of re-reading

From: Jan Kara
Date: Wed Apr 03 2024 - 07:01:57 EST


On Wed 03-04-24 10:10:08, linke li wrote:
> Currently, the __d_clear_type_and_inode() writes the value flags to
> dentry->d_flags, then immediately re-reads it in order to use it in a if
> statement. This re-read is useless because no other update to
> dentry->d_flags can occur at this point.
>
> This commit therefore re-use flags in the if statement instead of
> re-reading dentry->d_flags.
>
> Signed-off-by: linke li <lilinke99@xxxxxx>

Indeed, this seems pointless and actually a bit confusing. Feel free to
add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

Honza

> ---
> fs/dcache.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/dcache.c b/fs/dcache.c
> index b813528fb147..79da415d7995 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -355,7 +355,7 @@ static inline void __d_clear_type_and_inode(struct dentry *dentry)
> flags &= ~DCACHE_ENTRY_TYPE;
> WRITE_ONCE(dentry->d_flags, flags);
> dentry->d_inode = NULL;
> - if (dentry->d_flags & DCACHE_LRU_LIST)
> + if (flags & DCACHE_LRU_LIST)
> this_cpu_inc(nr_dentry_negative);
> }
>
> --
> 2.39.3 (Apple Git-146)
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR