On 2018/1/24 14:53, Gaoxiang (OS) wrote:
> Previously, we attempt to flush the whole cp pack in a single bio,
> however, when suddenly power off at this time, we could meet an
> extreme scenario that cp page1 and cp page2 are updated and latest,
> but payload or current summaries are still outdated.
> (see reliable write in UFS spec)
>
> This patch write the whole cp pack except cp page2 with FLUSH
> at first, and then write the cp page2 with an extra independent
> bio with FLUSH.
>
> Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
> ---
> fs/f2fs/checkpoint.c | 48 +++++++++++++++++++++++++++++++++++++++++-------
> fs/f2fs/f2fs.h | 3 ++-
> fs/f2fs/segment.c | 11 +++++++++--
> 3 files changed, 52 insertions(+), 10 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 14d2fed..e7f5e85 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -300,6 +300,35 @@ static int f2fs_write_meta_pages(struct address_space *mapping,
> return 0;
> }
>
> +static int sync_meta_page_locked(struct f2fs_sb_info *sbi,
> + struct page *page,
> + enum page_type type, enum iostat_type io_type)
> +{
> + struct writeback_control wbc = {
> + .for_reclaim = 0,
> + };
> + int err;
> +
> + BUG_ON(page->mapping != META_MAPPING(sbi));
> + BUG_ON(!PageDirty(page));
> +
> + f2fs_wait_on_page_writeback(page, META, true);
> +
> + BUG_ON(PageWriteback(page));
> + if (unlikely(!clear_page_dirty_for_io(page)))
> + BUG();
> +
> + err = __f2fs_write_meta_page(page, &wbc, io_type);
> + if (err) {
> + f2fs_put_page(page, 1);
> + return err;
> + }
> + f2fs_put_page(page, 0);
> +
> + f2fs_submit_merged_write(sbi, type);
> + return err;
> +}
> +
> long sync_meta_pages(struct f2fs_sb_info *sbi, enum page_type type,
> long nr_to_write, enum iostat_type io_type)
> {
> @@ -1172,6 +1201,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> struct curseg_info *seg_i = CURSEG_I(sbi, CURSEG_HOT_NODE);
> u64 kbytes_written;
> int err;
> + struct page *cp_page2;
>
> /* Flush all the NAT/SIT pages */
> while (get_pages(sbi, F2FS_DIRTY_META)) {
> @@ -1250,7 +1280,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> blk = start_blk + sbi->blocks_per_seg - nm_i->nat_bits_blocks;
> for (i = 0; i < nm_i->nat_bits_blocks; i++)
> update_meta_page(sbi, nm_i->nat_bits +
> - (i << F2FS_BLKSIZE_BITS), blk + i);
> + (i << F2FS_BLKSIZE_BITS), blk + i, NULL);
>
> /* Flush all the NAT BITS pages */
> while (get_pages(sbi, F2FS_DIRTY_META)) {
> @@ -1271,11 +1301,11 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> return err;
>
> /* write out checkpoint buffer at block 0 */
> - update_meta_page(sbi, ckpt, start_blk++);
> + update_meta_page(sbi, ckpt, start_blk++, NULL);
>
> for (i = 1; i < 1 + cp_payload_blks; i++)
> update_meta_page(sbi, (char *)ckpt + i * F2FS_BLKSIZE,
> - start_blk++);
> + start_blk++, NULL);
>
> if (orphan_num) {
> write_orphan_inodes(sbi, start_blk);
> @@ -1297,9 +1327,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> start_blk += NR_CURSEG_NODE_TYPE;
> }
>
> - /* writeout checkpoint block */
> - update_meta_page(sbi, ckpt, start_blk);
> -
> /* wait for previous submitted node/meta pages writeback */
> wait_on_all_pages_writeback(sbi);
>
> @@ -1313,12 +1340,19 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> sbi->last_valid_block_count = sbi->total_valid_block_count;
> percpu_counter_set(&sbi->alloc_valid_block_count, 0);
>
> - /* Here, we only have one bio having CP pack */
> + /* Here, we only have one bio having CP pack except cp page 2 */
> sync_meta_pages(sbi, META_FLUSH, LONG_MAX, FS_CP_META_IO);
We don't need to use META_FLUSH here.
>
> /* wait for previous submitted meta pages writeback */
> wait_on_all_pages_writeback(sbi);
>
> + /* write and flush checkpoint cp page 2 */
> + update_meta_page(sbi, ckpt, start_blk, &cp_page2);
> + sync_meta_page_locked(sbi, cp_page2, META_FLUSH, FS_CP_META_IO);
How about
sync_checkpoint()
{
page = grab_meta_page()
memcpy()
set_page_dirty()
...
__f2fs_write_meta_page()
f2fs_put_page()
f2fs_submit_merged_write()
}
BTW, could you give some numbers with this patch?
Thanks,
> +
> + /* wait for previous submitted meta pages writeback */
> + wait_on_all_pages_writeback(sbi);
> +
> release_ino_entry(sbi, false);
>
> if (unlikely(f2fs_cp_error(sbi)))
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index a4fb89d..7877ea3 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -2680,7 +2680,8 @@ void allocate_new_segments(struct f2fs_sb_info *sbi);
> int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range);
> bool exist_trim_candidates(struct f2fs_sb_info *sbi, struct cp_control *cpc);
> struct page *get_sum_page(struct f2fs_sb_info *sbi, unsigned int segno);
> -void update_meta_page(struct f2fs_sb_info *sbi, void *src, block_t blk_addr);
> +void update_meta_page(struct f2fs_sb_info *sbi,
> + void *src, block_t blk_addr, struct page **metapage);
> void write_meta_page(struct f2fs_sb_info *sbi, struct page *page,
> enum iostat_type io_type);
> void write_node_page(unsigned int nid, struct f2fs_io_info *fio);
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 40e1d20..f48a536 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1988,19 +1988,26 @@ struct page *get_sum_page(struct f2fs_sb_info *sbi, unsigned int segno)
> return get_meta_page(sbi, GET_SUM_BLOCK(sbi, segno));
> }
>
> -void update_meta_page(struct f2fs_sb_info *sbi, void *src, block_t blk_addr)
> +void update_meta_page(struct f2fs_sb_info *sbi,
> + void *src, block_t blk_addr, struct page **metapage)
> {
> struct page *page = grab_meta_page(sbi, blk_addr);
>
> memcpy(page_address(page), src, PAGE_SIZE);
> set_page_dirty(page);
> +
> + if (unlikely(metapage)) {
> + *metapage = page;
> + return;
> + }
> +
> f2fs_put_page(page, 1);
> }
>
> static void write_sum_page(struct f2fs_sb_info *sbi,
> struct f2fs_summary_block *sum_blk, block_t blk_addr)
> {
> - update_meta_page(sbi, (void *)sum_blk, blk_addr);
> + update_meta_page(sbi, (void *)sum_blk, blk_addr, NULL);
> }
>
> static void write_current_sum_page(struct f2fs_sb_info *sbi,
>
