Re: [PATCH v2 09/12] mm: Pass pvec directly to find_get_entries

From: Jan Kara
Date: Tue Sep 29 2020 - 05:07:23 EST


On Mon 14-09-20 14:00:39, Matthew Wilcox (Oracle) wrote:
> All callers of find_get_entries() use a pvec, so pass it directly
> instead of manipulating it in the caller.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

Honza

> ---
> include/linux/pagemap.h | 3 +--
> mm/filemap.c | 21 +++++++++------------
> mm/shmem.c | 5 ++---
> mm/swap.c | 4 +---
> 4 files changed, 13 insertions(+), 20 deletions(-)
>
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index d440c6750757..788c280737e0 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -414,8 +414,7 @@ static inline struct page *find_subpage(struct page *head, pgoff_t index)
> }
>
> unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
> - pgoff_t end, unsigned int nr_entries, struct page **entries,
> - pgoff_t *indices);
> + pgoff_t end, struct pagevec *pvec, pgoff_t *indices);
> unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
> pgoff_t end, unsigned int nr_pages,
> struct page **pages);
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 6dc0a9b8c0fa..a4ad294a34dc 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1800,14 +1800,12 @@ static inline struct page *xas_find_get_entry(struct xa_state *xas,
> * @mapping: The address_space to search
> * @start: The starting page cache index
> * @end: The final page index (inclusive).
> - * @nr_entries: The maximum number of entries
> - * @entries: Where the resulting entries are placed
> + * @pvec: Where the resulting entries are placed.
> * @indices: The cache indices corresponding to the entries in @entries
> *
> - * find_get_entries() will search for and return a group of up to
> - * @nr_entries entries in the mapping. The entries are placed at
> - * @entries. find_get_entries() takes a reference against any actual
> - * pages it returns.
> + * find_get_entries() will search for and return a batch of entries in
> + * the mapping. The entries are placed in @pvec. find_get_entries()
> + * takes a reference on any actual pages it returns.
> *
> * The search returns a group of mapping-contiguous page cache entries
> * with ascending indexes. There may be holes in the indices due to
> @@ -1824,15 +1822,12 @@ static inline struct page *xas_find_get_entry(struct xa_state *xas,
> * Return: the number of pages and shadow entries which were found.
> */
> unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
> - pgoff_t end, unsigned int nr_entries, struct page **entries,
> - pgoff_t *indices)
> + pgoff_t end, struct pagevec *pvec, pgoff_t *indices)
> {
> XA_STATE(xas, &mapping->i_pages, start);
> struct page *page;
> unsigned int ret = 0;
> -
> - if (!nr_entries)
> - return 0;
> + unsigned nr_entries = PAGEVEC_SIZE;
>
> rcu_read_lock();
> while ((page = xas_find_get_entry(&xas, end, XA_PRESENT))) {
> @@ -1847,11 +1842,13 @@ unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
> }
>
> indices[ret] = xas.xa_index;
> - entries[ret] = page;
> + pvec->pages[ret] = page;
> if (++ret == nr_entries)
> break;
> }
> rcu_read_unlock();
> +
> + pvec->nr = ret;
> return ret;
> }
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 404e45c285ca..b2b94025841a 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -963,9 +963,8 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
> while (index < end) {
> cond_resched();
>
> - pvec.nr = find_get_entries(mapping, index, end - 1,
> - PAGEVEC_SIZE, pvec.pages, indices);
> - if (!pvec.nr) {
> + if (!find_get_entries(mapping, index, end - 1, &pvec,
> + indices)) {
> /* If all gone or hole-punch or unfalloc, we're done */
> if (index == start || end != -1)
> break;
> diff --git a/mm/swap.c b/mm/swap.c
> index d4e3ba4c967c..40b23300d353 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -1060,9 +1060,7 @@ unsigned pagevec_lookup_entries(struct pagevec *pvec,
> struct address_space *mapping, pgoff_t start, pgoff_t end,
> pgoff_t *indices)
> {
> - pvec->nr = find_get_entries(mapping, start, end, PAGEVEC_SIZE,
> - pvec->pages, indices);
> - return pagevec_count(pvec);
> + return find_get_entries(mapping, start, end, pvec, indices);
> }
>
> /**
> --
> 2.28.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR