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Message-ID: <20161110200340.GA80797@jaegeuk>
Date: Thu, 10 Nov 2016 12:03:40 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [PATCH] f2fs: don't wait writeback for datas during checkpoint
Hi Chao,
On Thu, Nov 10, 2016 at 07:40:03PM +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.
>
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
> fs/f2fs/checkpoint.c | 2 +-
> fs/f2fs/data.c | 9 +++++++--
> fs/f2fs/debug.c | 7 ++++---
> fs/f2fs/f2fs.h | 26 +++++++++++++++++++++++---
> fs/f2fs/gc.c | 2 ++
> fs/f2fs/node.c | 1 +
> fs/f2fs/segment.c | 2 ++
> 7 files changed, 40 insertions(+), 9 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..2fb1ffd 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -73,6 +73,7 @@ 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 +81,10 @@ 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 +113,6 @@ 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 +273,9 @@ void f2fs_submit_page_mbio(struct f2fs_io_info *fio)
> verify_block_addr(sbi, fio->old_blkaddr);
> verify_block_addr(sbi, fio->new_blkaddr);
>
> + if (!is_read)
> + inc_page_count(sbi, fio->is_meta ? F2FS_WB_META : F2FS_WB_DATA);
> +
How about using f2fs_is_meta_data(page) instead of changing fio?
Thanks,
> down_write(&io->io_rwsem);
>
> if (io->bio && (io->last_block_in_bio != fio->new_blkaddr - 1 ||
> @@ -1237,6 +1241,7 @@ static int f2fs_write_data_page(struct page *page,
> .type = DATA,
> .op = REQ_OP_WRITE,
> .op_flags = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : 0,
> + .is_meta = S_ISDIR(inode->i_mode),
> .page = page,
> .encrypted_page = NULL,
> };
> 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..95ad091 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,
> };
>
> @@ -715,6 +717,7 @@ struct f2fs_io_info {
> enum page_type type; /* contains DATA/NODE/META/META_FLUSH */
> int op; /* contains REQ_OP_ */
> int op_flags; /* rq_flag_bits */
> + bool is_meta; /* checkpoint needs to wait its writeback */
> block_t new_blkaddr; /* new block address to be written */
> block_t old_blkaddr; /* old block address before Cow */
> struct page *page; /* page to be written */
> @@ -849,7 +852,6 @@ 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];
> @@ -1193,6 +1195,23 @@ static inline int check_nid_range(struct f2fs_sb_info *sbi, nid_t nid)
> return 0;
> }
>
> +static inline bool f2fs_is_meta_data(struct page *page)
> +{
> + struct address_space *mapping = page->mapping;
> + struct inode *inode;
> +
> + /* it is bounce page of encrypted regular inode */
> + if (!mapping)
> + return false;
> +
> + inode = mapping->host;
> + if (inode->i_ino == F2FS_NODE_INO(F2FS_I_SB(inode)) ||
> + inode->i_ino == F2FS_META_INO(F2FS_I_SB(inode)) ||
> + S_ISDIR(inode->i_mode))
> + return true;
> + return false;
> +}
> +
> #define F2FS_DEFAULT_ALLOCATED_BLOCKS 1
>
> /*
> @@ -1263,7 +1282,8 @@ 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 +2239,7 @@ 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;
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index f8d8cc96a..6b762d4 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -554,6 +554,7 @@ static void move_encrypted_block(struct inode *inode, block_t bidx,
> .type = DATA,
> .op = REQ_OP_READ,
> .op_flags = READ_SYNC,
> + .is_meta = true,
> .encrypted_page = NULL,
> };
> struct dnode_of_data dn;
> @@ -674,6 +675,7 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
> .type = DATA,
> .op = REQ_OP_WRITE,
> .op_flags = WRITE_SYNC,
> + .is_meta = S_ISDIR(inode->i_mode),
> .page = page,
> .encrypted_page = NULL,
> };
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index d58438f..3c7e00c 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1574,6 +1574,7 @@ static int f2fs_write_node_page(struct page *page,
> .type = NODE,
> .op = REQ_OP_WRITE,
> .op_flags = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : 0,
> + .is_meta = true,
> .page = page,
> .encrypted_page = NULL,
> };
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 078c571..b34e20a 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -261,6 +261,7 @@ static int __commit_inmem_pages(struct inode *inode,
> .type = DATA,
> .op = REQ_OP_WRITE,
> .op_flags = WRITE_SYNC | REQ_PRIO,
> + .is_meta = false,
> .encrypted_page = NULL,
> };
> bool submit_bio = false;
> @@ -1573,6 +1574,7 @@ void write_meta_page(struct f2fs_sb_info *sbi, struct page *page)
> .type = META,
> .op = REQ_OP_WRITE,
> .op_flags = WRITE_SYNC | REQ_META | REQ_PRIO,
> + .is_meta = true,
> .old_blkaddr = page->index,
> .new_blkaddr = page->index,
> .page = page,
> --
> 2.8.2.311.gee88674
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