Commit 50c7f34c authored by Kairui Song's avatar Kairui Song Committed by Andrew Morton
Browse files

mm, swap: remove no longer needed _swap_info_get 

There are now only two users of _swap_info_get after consolidating these
callers, folio_free_swap and swp_swapcount.

folio_free_swap already holds the folio lock, and the folio must be in the
swap cache, _swap_info_get is redundant.

For swp_swapcount, it should use get_swap_device instead.  get_swap_device
increases the device ref count, which is actually a bit safer.  The only
current use is smap walking, and the performance change here is tiny.

And after these changes, _swap_info_get is no longer used, so we can
safely remove it.

Link: https://lkml.kernel.org/r/20251220-swap-table-p2-v5-19-8862a265a033@tencent.com


Signed-off-by: default avatarKairui Song <kasong@tencent.com>
Reviewed-by: default avatarBaoquan He <bhe@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Deepanshu Kartikey <kartikey406@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent d3852f96

mm/swapfile.c

+6 −41
Original line number Diff line number Diff line
@@ -83,9 +83,7 @@ bool swap_migration_ad_supported; 
#endif	/* CONFIG_MIGRATION */



static const char Bad_file[] = "Bad swap file entry ";

static const char Unused_file[] = "Unused swap file entry ";

static const char Bad_offset[] = "Bad swap offset entry ";

static const char Unused_offset[] = "Unused swap offset entry ";



/*

 * all active swap_info_structs
@@ -1600,41 +1598,6 @@ void folio_put_swap(struct folio *folio, struct page *subpage) 
	swap_put_entries_cluster(si, swp_offset(entry), nr_pages, false);

}



static struct swap_info_struct *_swap_info_get(swp_entry_t entry)

{

	struct swap_info_struct *si;

	unsigned long offset;



	if (!entry.val)

		goto out;

	si = swap_entry_to_info(entry);

	if (!si)

		goto bad_nofile;

	if (data_race(!(si->flags & SWP_USED)))

		goto bad_device;

	offset = swp_offset(entry);

	if (offset >= si->max)

		goto bad_offset;

	if (data_race(!si->swap_map[swp_offset(entry)]) &&

	    !swap_cache_has_folio(entry))

		goto bad_free;

	return si;



bad_free:

	pr_err("%s: %s%08lx\n", __func__, Unused_offset, entry.val);

	goto out;

bad_offset:

	pr_err("%s: %s%08lx\n", __func__, Bad_offset, entry.val);

	goto out;

bad_device:

	pr_err("%s: %s%08lx\n", __func__, Unused_file, entry.val);

	goto out;

bad_nofile:

	pr_err("%s: %s%08lx\n", __func__, Bad_file, entry.val);

out:

	return NULL;

}



static void swap_put_entry_locked(struct swap_info_struct *si,

				  struct swap_cluster_info *ci,

				  unsigned long offset)
@@ -1794,7 +1757,7 @@ int swp_swapcount(swp_entry_t entry) 
	pgoff_t offset;

	unsigned char *map;



	si = _swap_info_get(entry);

	si = get_swap_device(entry);

	if (!si)

		return 0;
@@ -1824,6 +1787,7 @@ int swp_swapcount(swp_entry_t entry) 
	} while (tmp_count & COUNT_CONTINUED);

out:

	swap_cluster_unlock(ci);

	put_swap_device(si);

	return count;

}
@@ -1858,11 +1822,12 @@ static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, 
static bool folio_swapped(struct folio *folio)

{

	swp_entry_t entry = folio->swap;

	struct swap_info_struct *si = _swap_info_get(entry);

	struct swap_info_struct *si;



	if (!si)

		return false;

	VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);

	VM_WARN_ON_ONCE_FOLIO(!folio_test_swapcache(folio), folio);



	si = __swap_entry_to_info(entry);

	if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!folio_test_large(folio)))

		return swap_entry_swapped(si, entry);