On 2022/8/29 4:47, Vitaly Wool wrote:
> On Sat, Aug 27, 2022 at 12:12 PM Liu Shixin <liushixin2@xxxxxxxxxx> wrote:
>> Since we are supported to delay zswap initializaton, we need to invoke
>> ops->init for the swap device which is already online when register
>> backend.
>>
>> This patch is a revert of f328c1d16e4c ("frontswap: simplify frontswap_register_ops")
>> and 633423a09cb5 ("mm: mark swap_lock and swap_active_head static")
>>
>> Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
> Sorry, is this the revert of 2 patches at the same time? I would
> rather not do it like that.
>
> Thanks,
> Vitaly
Thanks for your advice, I'll split it to two patches and resend it.
>> ---
>> include/linux/swapfile.h | 2 ++
>> mm/frontswap.c | 47 ++++++++++++++++++++++++++++++++++++++++
>> mm/swapfile.c | 4 ++--
>> 3 files changed, 51 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/swapfile.h b/include/linux/swapfile.h
>> index 2fbcc9afd814..75fc069594a5 100644
>> --- a/include/linux/swapfile.h
>> +++ b/include/linux/swapfile.h
>> @@ -6,6 +6,8 @@
>> * these were static in swapfile.c but frontswap.c needs them and we don't
>> * want to expose them to the dozens of source files that include swap.h
>> */
>> +extern spinlock_t swap_lock;
>> +extern struct plist_head swap_active_head;
>> extern struct swap_info_struct *swap_info[];
>> extern unsigned long generic_max_swapfile_size(void);
>> /* Maximum swapfile size supported for the arch (not inclusive). */
>> diff --git a/mm/frontswap.c b/mm/frontswap.c
>> index 620f95af81dd..449e6f499b88 100644
>> --- a/mm/frontswap.c
>> +++ b/mm/frontswap.c
>> @@ -96,11 +96,58 @@ static inline void inc_frontswap_invalidates(void) { }
>> */
>> int frontswap_register_ops(const struct frontswap_ops *ops)
>> {
>> + DECLARE_BITMAP(a, MAX_SWAPFILES);
>> + DECLARE_BITMAP(b, MAX_SWAPFILES);
>> + struct swap_info_struct *si;
>> + unsigned int i;
>> +
>> if (frontswap_ops)
>> return -EINVAL;
>>
>> + bitmap_zero(a, MAX_SWAPFILES);
>> + bitmap_zero(b, MAX_SWAPFILES);
>> +
>> + spin_lock(&swap_lock);
>> + plist_for_each_entry(si, &swap_active_head, list) {
>> + if (!WARN_ON(!si->frontswap_map))
>> + __set_bit(si->type, a);
>> + }
>> + spin_unlock(&swap_lock);
>> +
>> + /* the new ops needs to know the currently active swap devices */
>> + for_each_set_bit(i, a, MAX_SWAPFILES) {
>> + pr_err("init frontswap_ops\n");
>> + ops->init(i);
>> + }
>> +
>> frontswap_ops = ops;
>> static_branch_inc(&frontswap_enabled_key);
>> +
>> + spin_lock(&swap_lock);
>> + plist_for_each_entry(si, &swap_active_head, list) {
>> + if (si->frontswap_map)
>> + __set_bit(si->type, b);
>> + }
>> + spin_unlock(&swap_lock);
>> +
>> + /*
>> + * On the very unlikely chance that a swap device was added or
>> + * removed between setting the "a" list bits and the ops init
>> + * calls, we re-check and do init or invalidate for any changed
>> + * bits.
>> + */
>> + if (unlikely(!bitmap_equal(a, b, MAX_SWAPFILES))) {
>> + for (i = 0; i < MAX_SWAPFILES; i++) {
>> + if (!test_bit(i, a) && test_bit(i, b)) {
>> + pr_err("init frontswap_ops re\n");
>> + ops->init(i);
>> + } else if (test_bit(i, a) && !test_bit(i, b)) {
>> + pr_err("inval frontswap_ops re\n");
>> + ops->invalidate_area(i);
>> + }
>> + }
>> + }
>> +
>> return 0;
>> }
>>
>> diff --git a/mm/swapfile.c b/mm/swapfile.c
>> index 469d9af86be2..d383b282f269 100644
>> --- a/mm/swapfile.c
>> +++ b/mm/swapfile.c
>> @@ -51,7 +51,7 @@ static bool swap_count_continued(struct swap_info_struct *, pgoff_t,
>> unsigned char);
>> static void free_swap_count_continuations(struct swap_info_struct *);
>>
>> -static DEFINE_SPINLOCK(swap_lock);
>> +DEFINE_SPINLOCK(swap_lock);
>> static unsigned int nr_swapfiles;
>> atomic_long_t nr_swap_pages;
>> /*
>> @@ -77,7 +77,7 @@ static const char Unused_offset[] = "Unused swap offset entry ";
>> * all active swap_info_structs
>> * protected with swap_lock, and ordered by priority.
>> */
>> -static PLIST_HEAD(swap_active_head);
>> +PLIST_HEAD(swap_active_head);
>>
>> /*
>> * all available (active, not full) swap_info_structs
>> --
>> 2.25.1
>>
> .
>
