2022-07-01 19:06:49

by Ira Weiny

[permalink] [raw]
Subject: Re: [PATCH] nfs: Replace kmap() with kmap_local_page()

On Tue, Jun 28, 2022 at 08:24:26PM +0200, Fabio M. De Francesco wrote:
> The use of kmap() is being deprecated in favor of kmap_local_page().
>
> With kmap_local_page(), the mapping is per thread, CPU local and not
> globally visible. Furthermore, the mapping can be acquired from any context
> (including interrupts).
>
> Therefore, use kmap_local_page() in nfs_do_filldir() because this mapping
> is per thread, CPU local, and not globally visible.
>
> Suggested-by: Ira Weiny <[email protected]>

Reviewed-by: Ira Weiny <[email protected]>

> Signed-off-by: Fabio M. De Francesco <[email protected]>
> ---
>
> I cannot test this patch for several reasons. While these changes seem safe
> and trivial, I would feel better if people familiar with NFS could take the
> time to properly test this patch. Thank you.
>
> fs/nfs/dir.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 0c4e8dd6aa96..8b89f10d8899 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -1084,7 +1084,7 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc,
> struct nfs_cache_array *array;
> unsigned int i;
>
> - array = kmap(desc->page);
> + array = kmap_local_page(desc->page);
> for (i = desc->cache_entry_index; i < array->size; i++) {
> struct nfs_cache_array_entry *ent;
>
> @@ -1110,7 +1110,7 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc,
> if (array->page_is_eof)
> desc->eof = !desc->eob;
>
> - kunmap(desc->page);
> + kunmap_local(array);
> dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %llu\n",
> (unsigned long long)desc->dir_cookie);
> }
> --
> 2.36.1
>