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From:   Kairui Song <ryncsn@gmail.com>
To:     linux-mm@kvack.org
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        "Huang, Ying" <ying.huang@intel.com>,
        David Hildenbrand <david@redhat.com>,
        Hugh Dickins <hughd@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Matthew Wilcox <willy@infradead.org>,
        Michal Hocko <mhocko@suse.com>, linux-kernel@vger.kernel.org,
        Kairui Song <kasong@tencent.com>
Subject: [PATCH 09/24] mm/swap: inline __swap_count
Date:   Mon, 20 Nov 2023 03:47:25 +0800
Message-ID: <20231119194740.94101-10-ryncsn@gmail.com>
In-Reply-To: <20231119194740.94101-1-ryncsn@gmail.com>
References: <20231119194740.94101-1-ryncsn@gmail.com>
Reply-To: Kairui Song <kasong@tencent.com>
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From: Kairui Song <kasong@tencent.com>

There is only one caller in swap subsystem now, where it can be inline
smoothly, avoid the memory access and function call overheads.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
 include/linux/swap.h | 6 ------
 mm/swap_state.c      | 6 +++---
 mm/swapfile.c        | 8 --------
 3 files changed, 3 insertions(+), 17 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 2401990d954d..64a37819a9b3 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -485,7 +485,6 @@ int swap_type_of(dev_t device, sector_t offset);
 int find_first_swap(dev_t *device);
 extern unsigned int count_swap_pages(int, int);
 extern sector_t swapdev_block(int, pgoff_t);
-extern int __swap_count(swp_entry_t entry);
 extern int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry);
 extern int swp_swapcount(swp_entry_t entry);
 extern struct swap_info_struct *page_swap_info(struct page *);
@@ -559,11 +558,6 @@ static inline void put_swap_folio(struct folio *folio, swp_entry_t swp)
 {
 }
 
-static inline int __swap_count(swp_entry_t entry)
-{
-	return 0;
-}
-
 static inline int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)
 {
 	return 0;
diff --git a/mm/swap_state.c b/mm/swap_state.c
index fb78f7f18ed7..d87c20f9f7ec 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -316,9 +316,9 @@ void free_pages_and_swap_cache(struct encoded_page **pages, int nr)
 	release_pages(pages, nr);
 }
 
-static inline bool swap_use_no_readahead(struct swap_info_struct *si, swp_entry_t entry)
+static inline bool swap_use_no_readahead(struct swap_info_struct *si, pgoff_t offset)
 {
-	return data_race(si->flags & SWP_SYNCHRONOUS_IO) && __swap_count(entry) == 1;
+	return data_race(si->flags & SWP_SYNCHRONOUS_IO) && swap_count(si->swap_map[offset]) == 1;
 }
 
 static inline bool swap_use_vma_readahead(struct swap_info_struct *si)
@@ -928,7 +928,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
 
 	si = swp_swap_info(entry);
 	mpol = get_vma_policy(vmf->vma, vmf->address, 0, &ilx);
-	if (swap_use_no_readahead(si, entry)) {
+	if (swap_use_no_readahead(si, swp_offset(entry))) {
 		page = swapin_no_readahead(entry, gfp_mask, mpol, ilx, vmf->vma->vm_mm);
 		cached = false;
 	} else if (swap_use_vma_readahead(si)) {
diff --git a/mm/swapfile.c b/mm/swapfile.c
index a8ae472ed2b6..e15a6c464a38 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1431,14 +1431,6 @@ void swapcache_free_entries(swp_entry_t *entries, int n)
 		spin_unlock(&p->lock);
 }
 
-int __swap_count(swp_entry_t entry)
-{
-	struct swap_info_struct *si = swp_swap_info(entry);
-	pgoff_t offset = swp_offset(entry);
-
-	return swap_count(si->swap_map[offset]);
-}
-
 /*
  * How many references to @entry are currently swapped out?
  * This does not give an exact answer when swap count is continued,
-- 
2.42.0