Hi Jaegeuk, On 2016/11/15 7:32, Jaegeuk Kim wrote: > Hi Chao, > > On Mon, Nov 14, 2016 at 07:04:12PM +0800, Chao Yu wrote: >> Normally, while committing checkpoint, we will wait on all pages to be >> writebacked no matter the page is data or metadata, so in scenario where >> there are lots of data IO being submitted with metadata, we may suffer >> long latency for waiting writeback during checkpoint. >> >> Indeed, we only care about persistence for pages with metadata, but not >> pages with data, as file system consistent are only related to metadate, >> so in order to avoid encountering long latency in above scenario, let's >> recognize and reference metadata in submitted IOs, wait writeback only >> for metadatas. > > Hmm, another concern comes, which is related to GCed data like below scenario. > > 1. Write data X > 2. Sync > 3. Move data X by GC > 4. Checkpoint > 5. Power-cut > > In this case, we should guarantee data X which was migrated by GC during #3. > If we don't care about end_io in #4 Checkpoint, we can lose the data after > #5 Power-cut. > > Any idea?
Yes, good catch. :) What about tagging these GCed page as cold data through set_cold_data, and clear the tag in end_io, then we can keep reference count and wait on writeback for them? Thanks, > > Thanks, > >> >> Signed-off-by: Chao Yu <[email protected]> >> --- >> fs/f2fs/checkpoint.c | 2 +- >> fs/f2fs/data.c | 36 ++++++++++++++++++++++++++++++++---- >> fs/f2fs/debug.c | 7 ++++--- >> fs/f2fs/f2fs.h | 8 +++++--- >> 4 files changed, 42 insertions(+), 11 deletions(-) >> >> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c >> index 7bece59..bdf8a50 100644 >> --- a/fs/f2fs/checkpoint.c >> +++ b/fs/f2fs/checkpoint.c >> @@ -1003,7 +1003,7 @@ static void wait_on_all_pages_writeback(struct >> f2fs_sb_info *sbi) >> for (;;) { >> prepare_to_wait(&sbi->cp_wait, &wait, TASK_UNINTERRUPTIBLE); >> >> - if (!atomic_read(&sbi->nr_wb_bios)) >> + if (!get_pages(sbi, F2FS_WB_META)) >> break; >> >> io_schedule_timeout(5*HZ); >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >> index 66d2aee..f52cec3 100644 >> --- a/fs/f2fs/data.c >> +++ b/fs/f2fs/data.c >> @@ -29,6 +29,26 @@ >> #include "trace.h" >> #include <trace/events/f2fs.h> >> >> +static bool f2fs_is_meta_data(struct page *page) >> +{ >> + struct address_space *mapping = page->mapping; >> + struct f2fs_sb_info *sbi; >> + struct inode *inode; >> + >> + /* it is bounce page of encrypted regular inode */ >> + if (!mapping) >> + return false; >> + >> + inode = mapping->host; >> + sbi = F2FS_I_SB(inode); >> + >> + if ((inode->i_ino == F2FS_META_INO(sbi) && >> + page->index < MAIN_BLKADDR(sbi)) || >> + inode->i_ino == F2FS_NODE_INO(sbi) || >> + S_ISDIR(inode->i_mode)) >> + return true; >> + return false; >> +} >> static void f2fs_read_end_io(struct bio *bio) >> { >> struct bio_vec *bvec; >> @@ -73,6 +93,7 @@ static void f2fs_write_end_io(struct bio *bio) >> >> bio_for_each_segment_all(bvec, bio, i) { >> struct page *page = bvec->bv_page; >> + bool is_meta = f2fs_is_meta_data(page); >> >> fscrypt_pullback_bio_page(&page, true); >> >> @@ -80,9 +101,10 @@ static void f2fs_write_end_io(struct bio *bio) >> mapping_set_error(page->mapping, -EIO); >> f2fs_stop_checkpoint(sbi, true); >> } >> + dec_page_count(sbi, is_meta ? F2FS_WB_META : F2FS_WB_DATA); >> end_page_writeback(page); >> } >> - if (atomic_dec_and_test(&sbi->nr_wb_bios) && >> + if (!get_pages(sbi, F2FS_WB_META) && >> wq_has_sleeper(&sbi->cp_wait)) >> wake_up(&sbi->cp_wait); >> >> @@ -111,7 +133,6 @@ static inline void __submit_bio(struct f2fs_sb_info *sbi, >> struct bio *bio, enum page_type type) >> { >> if (!is_read_io(bio_op(bio))) { >> - atomic_inc(&sbi->nr_wb_bios); >> if (f2fs_sb_mounted_blkzoned(sbi->sb) && >> current->plug && (type == DATA || type == NODE)) >> blk_finish_plug(current->plug); >> @@ -272,6 +293,15 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *fio) >> verify_block_addr(sbi, fio->old_blkaddr); >> verify_block_addr(sbi, fio->new_blkaddr); >> >> + bio_page = fio->encrypted_page ? fio->encrypted_page : fio->page; >> + >> + if (!is_read) { >> + bool is_meta; >> + >> + is_meta = f2fs_is_meta_data(bio_page); >> + inc_page_count(sbi, is_meta ? F2FS_WB_META : F2FS_WB_DATA); >> + } >> + >> down_write(&io->io_rwsem); >> >> if (io->bio && (io->last_block_in_bio != fio->new_blkaddr - 1 || >> @@ -284,8 +314,6 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *fio) >> io->fio = *fio; >> } >> >> - bio_page = fio->encrypted_page ? fio->encrypted_page : fio->page; >> - >> if (bio_add_page(io->bio, bio_page, PAGE_SIZE, 0) < >> PAGE_SIZE) { >> __submit_merged_bio(io); >> diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c >> index 2fdf233..f2d87de 100644 >> --- a/fs/f2fs/debug.c >> +++ b/fs/f2fs/debug.c >> @@ -50,7 +50,8 @@ static void update_general_status(struct f2fs_sb_info *sbi) >> si->ndirty_files = sbi->ndirty_inode[FILE_INODE]; >> si->ndirty_all = sbi->ndirty_inode[DIRTY_META]; >> si->inmem_pages = get_pages(sbi, F2FS_INMEM_PAGES); >> - si->wb_bios = atomic_read(&sbi->nr_wb_bios); >> + si->nr_wb_meta = get_pages(sbi, F2FS_WB_META); >> + si->nr_wb_data = get_pages(sbi, F2FS_WB_DATA); >> si->total_count = (int)sbi->user_block_count / sbi->blocks_per_seg; >> si->rsvd_segs = reserved_segments(sbi); >> si->overp_segs = overprovision_segments(sbi); >> @@ -313,8 +314,8 @@ static int stat_show(struct seq_file *s, void *v) >> seq_printf(s, " - Inner Struct Count: tree: %d(%d), node: >> %d\n", >> si->ext_tree, si->zombie_tree, si->ext_node); >> seq_puts(s, "\nBalancing F2FS Async:\n"); >> - seq_printf(s, " - inmem: %4d, wb_bios: %4d\n", >> - si->inmem_pages, si->wb_bios); >> + seq_printf(s, " - inmem: %4d, wb_meta: %4d, wb_data: %4d\n", >> + si->inmem_pages, si->nr_wb_meta, si->nr_wb_data); >> seq_printf(s, " - nodes: %4d in %4d\n", >> si->ndirty_node, si->node_pages); >> seq_printf(s, " - dents: %4d in dirs:%4d (%4d)\n", >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >> index 23a937f..4df301c 100644 >> --- a/fs/f2fs/f2fs.h >> +++ b/fs/f2fs/f2fs.h >> @@ -682,6 +682,8 @@ enum count_type { >> F2FS_DIRTY_META, >> F2FS_INMEM_PAGES, >> F2FS_DIRTY_IMETA, >> + F2FS_WB_META, >> + F2FS_WB_DATA, >> NR_COUNT_TYPE, >> }; >> >> @@ -849,7 +851,6 @@ struct f2fs_sb_info { >> block_t discard_blks; /* discard command candidats */ >> block_t last_valid_block_count; /* for recovery */ >> u32 s_next_generation; /* for NFS support */ >> - atomic_t nr_wb_bios; /* # of writeback bios */ >> >> /* # of pages, see count_type */ >> atomic_t nr_pages[NR_COUNT_TYPE]; >> @@ -1263,7 +1264,8 @@ static inline void inc_page_count(struct f2fs_sb_info >> *sbi, int count_type) >> { >> atomic_inc(&sbi->nr_pages[count_type]); >> >> - if (count_type == F2FS_DIRTY_DATA || count_type == F2FS_INMEM_PAGES) >> + if (count_type == F2FS_DIRTY_DATA || count_type == F2FS_INMEM_PAGES || >> + count_type == F2FS_WB_META || count_type == F2FS_WB_DATA) >> return; >> >> set_sbi_flag(sbi, SBI_IS_DIRTY); >> @@ -2219,7 +2221,7 @@ struct f2fs_stat_info { >> unsigned int ndirty_dirs, ndirty_files, ndirty_all; >> int nats, dirty_nats, sits, dirty_sits, free_nids, alloc_nids; >> int total_count, utilization; >> - int bg_gc, wb_bios; >> + int bg_gc, nr_wb_meta, nr_wb_data; >> int inline_xattr, inline_inode, inline_dir, orphans; >> unsigned int valid_count, valid_node_count, valid_inode_count, >> discard_blks; >> unsigned int bimodal, avg_vblocks; >> -- >> 2.8.2.311.gee88674 > > . >
