[PATCH v5 11/19] mm, swap: split locked entry duplicating into a standalone helper

Kairui Song
2025-12-19T19:45:10Z

No feature change, split the common logic into a stand alone helper to
be reused later.

Signed-off-by: Kairui Song <kasong@tencent.com>
---
mm/swapfile.c | 62 +++++++++++++++++++++++++++++------------------------------
1 file changed, 31 insertions(+), 31 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index f3516e3c9e40..c878c4115d00 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3667,26 +3667,14 @@ void si_swapinfo(struct sysinfo *val)
* - swap-cache reference is requested but the entry is not used. -> ENOENT
* - swap-mapped reference requested but needs continued swap count. -> ENOMEM
*/
-static int __swap_duplicate(swp_entry_t entry, unsigned char usage, int nr)
+static int swap_dup_entries(struct swap_info_struct *si,
+ struct swap_cluster_info *ci,
+ unsigned long offset,
+ unsigned char usage, int nr)
{
- struct swap_info_struct *si;
- struct swap_cluster_info *ci;
- unsigned long offset;
- unsigned char count;
- unsigned char has_cache;
- int err, i;
-
- si = swap_entry_to_info(entry);
- if (WARN_ON_ONCE(!si)) {
- pr_err("%s%08lx\n", Bad_file, entry.val);
- return -EINVAL;
- }
-
- offset = swp_offset(entry);
- VM_WARN_ON(nr > SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER);
- ci = swap_cluster_lock(si, offset);
+ int i;
+ unsigned char count, has_cache;

- err = 0;
for (i = 0; i < nr; i++) {
count = si->swap_map[offset + i];

@@ -3694,25 +3682,20 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage, int nr)
* For swapin out, allocator never allocates bad slots. for
* swapin, readahead is guarded by swap_entry_swapped.
*/
- if (WARN_ON(swap_count(count) == SWAP_MAP_BAD)) {
- err = -ENOENT;
- goto unlock_out;
- }
+ if (WARN_ON(swap_count(count) == SWAP_MAP_BAD))
+ return -ENOENT;

has_cache = count & SWAP_HAS_CACHE;
count &= ~SWAP_HAS_CACHE;

if (!count && !has_cache) {
- err = -ENOENT;
+ return -ENOENT;
} else if (usage == SWAP_HAS_CACHE) {
if (has_cache)
- err = -EEXIST;
+ return -EEXIST;
} else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) {
- err = -EINVAL;
+ return -EINVAL;
}
-
- if (err)
- goto unlock_out;
}

for (i = 0; i < nr; i++) {
@@ -3731,14 +3714,31 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage, int nr)
* Don't need to rollback changes, because if
* usage == 1, there must be nr == 1.
*/
- err = -ENOMEM;
- goto unlock_out;
+ return -ENOMEM;
}

WRITE_ONCE(si->swap_map[offset + i], count | has_cache);
}

-unlock_out:
+ return 0;
+}
+
+static int __swap_duplicate(swp_entry_t entry, unsigned char usage, int nr)
+{
+ int err;
+ struct swap_info_struct *si;
+ struct swap_cluster_info *ci;
+ unsigned long offset = swp_offset(entry);
+
+ si = swap_entry_to_info(entry);
+ if (WARN_ON_ONCE(!si)) {
+ pr_err("%s%08lx\n", Bad_file, entry.val);
+ return -EINVAL;
+ }
+
+ VM_WARN_ON(nr > SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER);
+ ci = swap_cluster_lock(si, offset);
+ err = swap_dup_entries(si, ci, offset, usage, nr);
swap_cluster_unlock(ci);
return err;
}

--
2.52.0