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 <[email protected]>
---
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)
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 <[email protected]>
Indeed, this seems pointless and actually a bit confusing. Feel free to
add:
Reviewed-by: Jan Kara <[email protected]>
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 <[email protected]>
SUSE Labs, CR
On Wed, 03 Apr 2024 10:10:08 +0800, 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.
>
> [...]
Applied to the vfs.misc branch of the vfs/vfs.git tree.
Patches in the vfs.misc branch should appear in linux-next soon.
Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.
It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.
Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.misc
[1/1] fs/dcache: Re-use value stored to dentry->d_flags instead of re-reading
https://git.kernel.org/vfs/vfs/c/8bfb40be31dd