On 2016/9/19 22:48, Chao Yu wrote:
> On 2016/9/20 5:03, Weichao Guo wrote:
>> This patch improves the migration of dirty pages and allows migrating atomic
>> written pages that F2FS uses in Page Cache. Instead of the fallback releasing
>> page path, it provides better performance for memory compaction, CMA and
>> other
>> users of memory page migrating. For dirty pages, there is no need to write
>> back
>> first when migrating. For an atomic written page before committing, we can
>> migrate the page and update the related 'inmem_pages' list at the same time.
>>
>> Signed-off-by: Weichao Guo <guoweic...@huawei.com>
>> ---
>> fs/f2fs/checkpoint.c | 3 +++
>> fs/f2fs/data.c | 56
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
>> fs/f2fs/f2fs.h | 4 ++++
>> fs/f2fs/node.c | 3 +++
>> 4 files changed, 66 insertions(+)
>>
>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>> index df56a43..a366521 100644
>> --- a/fs/f2fs/checkpoint.c
>> +++ b/fs/f2fs/checkpoint.c
>> @@ -388,6 +388,9 @@ const struct address_space_operations f2fs_meta_aops = {
>> .set_page_dirty = f2fs_set_meta_page_dirty,
>> .invalidatepage = f2fs_invalidate_page,
>> .releasepage = f2fs_release_page,
>> +#ifdef CONFIG_MIGRATION
>> + .migratepage = f2fs_migrate_page,
>> +#endif
>> };
>>
>> static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)
>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>> index 528c3c0..eb0d63f 100644
>> --- a/fs/f2fs/data.c
>> +++ b/fs/f2fs/data.c
>> @@ -1882,6 +1882,59 @@ static sector_t f2fs_bmap(struct address_space
>> *mapping, sector_t block)
>> return generic_block_bmap(mapping, block, get_data_block_bmap);
>> }
>>
>> +#ifdef CONFIG_MIGRATION
>> +
>> +#include <linux/migrate.h>
>> +
>> +int f2fs_migrate_page(struct address_space *mapping,
>> + struct page *newpage, struct page *page, enum migrate_mode mode)
>> +{
>> + int rc, extra_count;
>> + struct f2fs_inode_info *fi = F2FS_I(mapping->host);
>> + bool atomic_written = IS_ATOMIC_WRITTEN_PAGE(page);
>> +
>> + BUG_ON(PageWriteback(page));
>> +
>> + /* migrating an atomic written page is safe with the inmem_lock hold */
>> + if (atomic_written && !mutex_trylock(&fi->inmem_lock))
>> + return -EAGAIN;
>> +
>> + /*
>> + * A reference is expected if PagePrivate set when move mapping,
>> + * however F2FS breaks this for maintaining dirty page counts when
>> + * truncating pages. So here adjusting the 'extra_count' make it work.
>> + */
>> + extra_count = (atomic_written ? 1 : 0) - page_has_private(page);
>> + rc = migrate_page_move_mapping(mapping, newpage,
>> + page, NULL, mode, extra_count);
>> + if (rc != MIGRATEPAGE_SUCCESS) {
>> + if (atomic_written)
>> + mutex_unlock(&fi->inmem_lock);
>> + return rc;
>> + }
>> +
>> + if (atomic_written) {
>> + struct inmem_pages *cur;
>> + list_for_each_entry(cur, &fi->inmem_pages, list)
>> + if (cur->page == page) {
>> + cur->page = newpage;
>> + break;
>> + }
>> + mutex_unlock(&fi->inmem_lock);
>> + put_page(page);
>> + get_page(newpage);
>
> Should we also do put_page(oldpage) & get_page(newpage) for
> non-atomic-written page?
>
No, the 'page_count' of the old/new page for Page Cache has been maintained in
'migrate_page_move_mapping'. As atomic-written pages have an additional
reference, we should update their 'page_count' here.
> Thanks,
>
>> + }
>> +
>> + if (PagePrivate(page))
>> + SetPagePrivate(newpage);
>> + set_page_private(newpage, page_private(page));
>> +
>> + migrate_page_copy(newpage, page);
>> +
>> + return MIGRATEPAGE_SUCCESS;
>> +}
>> +#endif
>> +
>> const struct address_space_operations f2fs_dblock_aops = {
>> .readpage = f2fs_read_data_page,
>> .readpages = f2fs_read_data_pages,
>> @@ -1894,4 +1947,7 @@ const struct address_space_operations f2fs_dblock_aops
>> = {
>> .releasepage = f2fs_release_page,
>> .direct_IO = f2fs_direct_IO,
>> .bmap = f2fs_bmap,
>> +#ifdef CONFIG_MIGRATION
>> + .migratepage = f2fs_migrate_page,
>> +#endif
>> };
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 5d2aa6a..b951482 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -2126,6 +2126,10 @@ int f2fs_fiemap(struct inode *inode, struct
>> fiemap_extent_info *, u64, u64);
>> void f2fs_set_page_dirty_nobuffers(struct page *);
>> void f2fs_invalidate_page(struct page *, unsigned int, unsigned int);
>> int f2fs_release_page(struct page *, gfp_t);
>> +#ifdef CONFIG_MIGRATION
>> +int f2fs_migrate_page(struct address_space *mapping,
>> + struct page *newpage, struct page *page, enum migrate_mode mode);
>> +#endif
>>
>> /*
>> * gc.c
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index 2322a8e..55c22a9 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -1670,6 +1670,9 @@ const struct address_space_operations f2fs_node_aops =
>> {
>> .set_page_dirty = f2fs_set_node_page_dirty,
>> .invalidatepage = f2fs_invalidate_page,
>> .releasepage = f2fs_release_page,
>> +#ifdef CONFIG_MIGRATION
>> + .migratepage = f2fs_migrate_page,
>> +#endif
>> };
>>
>> static struct free_nid *__lookup_free_nid_list(struct f2fs_nm_info *nm_i,
>>
>
> .
>
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