[PATCH v3 1/8] swap: remove remnants of polling from read_swap_cache_async

Suren Baghdasaryan
2023-06-27T04:23:31Z

Commit [1] introduced IO polling support duding swapin to reduce
swap read latency for block devices that can be polled. However later
commit [2] removed polling support. Therefore it seems safe to remove
do_poll parameter in read_swap_cache_async and always call swap_readpage
with synchronous=false waiting for IO completion in folio_lock_or_retry.

[1] commit 23955622ff8d ("swap: add block io poll in swapin path")
[2] commit 9650b453a3d4 ("block: ignore RWF_HIPRI hint for sync dio")

Suggested-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
mm/madvise.c | 4 ++--
mm/swap.h | 1 -
mm/swap_state.c | 12 +++++-------
3 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index b5ffbaf616f5..b1e8adf1234e 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -215,7 +215,7 @@ static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
continue;

page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
- vma, index, false, &splug);
+ vma, index, &splug);
if (page)
put_page(page);
}
@@ -252,7 +252,7 @@ static void force_shm_swapin_readahead(struct vm_area_struct *vma,
rcu_read_unlock();

page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
- NULL, 0, false, &splug);
+ NULL, 0, &splug);
if (page)
put_page(page);

diff --git a/mm/swap.h b/mm/swap.h
index 7c033d793f15..8a3c7a0ace4f 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -46,7 +46,6 @@ struct folio *filemap_get_incore_folio(struct address_space *mapping,
struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
struct vm_area_struct *vma,
unsigned long addr,
- bool do_poll,
struct swap_iocb **plug);
struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
struct vm_area_struct *vma,
diff --git a/mm/swap_state.c b/mm/swap_state.c
index b76a65ac28b3..a3839de71f3f 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -517,15 +517,14 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
*/
struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
struct vm_area_struct *vma,
- unsigned long addr, bool do_poll,
- struct swap_iocb **plug)
+ unsigned long addr, struct swap_iocb **plug)
{
bool page_was_allocated;
struct page *retpage = __read_swap_cache_async(entry, gfp_mask,
vma, addr, &page_was_allocated);

if (page_was_allocated)
- swap_readpage(retpage, do_poll, plug);
+ swap_readpage(retpage, false, plug);

return retpage;
}
@@ -620,7 +619,7 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
struct swap_info_struct *si = swp_swap_info(entry);
struct blk_plug plug;
struct swap_iocb *splug = NULL;
- bool do_poll = true, page_allocated;
+ bool page_allocated;
struct vm_area_struct *vma = vmf->vma;
unsigned long addr = vmf->address;

@@ -628,7 +627,6 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
if (!mask)
goto skip;

- do_poll = false;
/* Read a page_cluster sized and aligned cluster around offset. */
start_offset = offset & ~mask;
end_offset = offset | mask;
@@ -660,7 +658,7 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
lru_add_drain(); /* Push any new pages onto the LRU now */
skip:
/* The page was likely read above, so no need for plugging here */
- return read_swap_cache_async(entry, gfp_mask, vma, addr, do_poll, NULL);
+ return read_swap_cache_async(entry, gfp_mask, vma, addr, NULL);
}

int init_swap_address_space(unsigned int type, unsigned long nr_pages)
@@ -825,7 +823,7 @@ static struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask,
skip:
/* The page was likely read above, so no need for plugging here */
return read_swap_cache_async(fentry, gfp_mask, vma, vmf->address,
- ra_info.win == 1, NULL);
+ NULL);
}

/**
--
2.41.0.178.g377b9f9a00-goog