Re: [PATCH v2 2/2] dax: use PG_PMD_COLOUR instead of open coding

From: Jan Kara
Date: Wed Aug 23 2017 - 05:58:49 EST


On Tue 22-08-17 16:24:36, Ross Zwisler wrote:
> Use ~PG_PMD_COLOUR in dax_entry_waitqueue() instead of open coding an
> equivalent page offset mask.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

Honza

> ---
> fs/dax.c | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 865d42c..0e2a1fd 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -42,6 +42,9 @@
> #define DAX_WAIT_TABLE_BITS 12
> #define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS)
>
> +/* The 'colour' (ie low bits) within a PMD of a page offset. */
> +#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
> +
> static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES];
>
> static int __init init_dax_wait_table(void)
> @@ -98,7 +101,7 @@ static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping,
> * the range covered by the PMD map to the same bit lock.
> */
> if (dax_is_pmd_entry(entry))
> - index &= ~((1UL << (PMD_SHIFT - PAGE_SHIFT)) - 1);
> + index &= ~PG_PMD_COLOUR;
>
> key->mapping = mapping;
> key->entry_start = index;
> @@ -1262,12 +1265,6 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf,
> }
>
> #ifdef CONFIG_FS_DAX_PMD
> -/*
> - * The 'colour' (ie low bits) within a PMD of a page offset. This comes up
> - * more often than one might expect in the below functions.
> - */
> -#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
> -
> static int dax_pmd_insert_mapping(struct vm_fault *vmf, struct iomap *iomap,
> loff_t pos, void **entryp)
> {
> --
> 2.9.5
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR