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Date: Thu, 11 May 2017 11:36:00 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>
Subject: Re: [PATCH 3/3] f2fs: introduce io_list for serialize data/node IOs
Hi Chao,
On 05/09, Chao Yu wrote:
> From: Chao Yu <yuchao0@...wei.com>
>
> Serialize data/node IOs by using fifo list instead of mutex lock,
> it will help to enhance concurrency of f2fs, meanwhile keeping LFS
> IO semantics.
I'm not against to give it a try, but not sure how much we can get a benefit
from this approach frankly. Have you got a trouble on any lock contention from
the below io_rwsem or mutex?
Thanks,
>
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
> fs/f2fs/checkpoint.c | 1 +
> fs/f2fs/data.c | 28 ++++++++++++++++++++++++----
> fs/f2fs/f2fs.h | 5 ++++-
> fs/f2fs/gc.c | 3 ++-
> fs/f2fs/segment.c | 20 ++++++++++++++------
> fs/f2fs/segment.h | 3 ++-
> 6 files changed, 47 insertions(+), 13 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 2a475e83a092..7b3393474f6b 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -162,6 +162,7 @@ int ra_meta_pages(struct f2fs_sb_info *sbi, block_t start, int nrpages,
> .op = REQ_OP_READ,
> .op_flags = sync ? (REQ_META | REQ_PRIO) : REQ_RAHEAD,
> .encrypted_page = NULL,
> + .in_list = false,
> };
> struct blk_plug plug;
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 5f001b471252..89eaa8aaa97b 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -393,10 +393,28 @@ int f2fs_submit_page_mbio(struct f2fs_io_info *fio)
> struct f2fs_bio_info *io;
> bool is_read = is_read_io(fio->op);
> struct page *bio_page;
> + struct curseg_info *curseg;
> int err = 0;
>
> + if (fio->in_list)
> + curseg = CURSEG_I(sbi, fio->seg_type);
> +
> io = __get_bio_info(sbi, fio->op, fio->type, fio->seg_type);
>
> + down_write(&io->io_rwsem);
> +next:
> + if (fio->in_list) {
> + spin_lock(&curseg->io_lock);
> + if (list_empty(&curseg->io_list)) {
> + spin_unlock(&curseg->io_lock);
> + goto out_fail;
> + }
> + fio = list_first_entry(&curseg->io_list,
> + struct f2fs_io_info, list);
> + list_del(&fio->list);
> + spin_unlock(&curseg->io_lock);
> + }
> +
> if (fio->old_blkaddr != NEW_ADDR)
> verify_block_addr(sbi, fio->old_blkaddr);
> verify_block_addr(sbi, fio->new_blkaddr);
> @@ -409,8 +427,6 @@ int f2fs_submit_page_mbio(struct f2fs_io_info *fio)
> if (!is_read)
> inc_page_count(sbi, WB_DATA_TYPE(bio_page));
>
> - down_write(&io->io_rwsem);
> -
> if (io->bio && (io->last_block_in_bio != fio->new_blkaddr - 1 ||
> (io->fio.op != fio->op || io->fio.op_flags != fio->op_flags) ||
> !__same_bdev(sbi, fio->new_blkaddr, io->bio)))
> @@ -437,9 +453,13 @@ int f2fs_submit_page_mbio(struct f2fs_io_info *fio)
>
> io->last_block_in_bio = fio->new_blkaddr;
> f2fs_trace_ios(fio, 0);
> +
> + trace_f2fs_submit_page_mbio(fio->page, fio);
> +
> + if (fio->in_list)
> + goto next;
> out_fail:
> up_write(&io->io_rwsem);
> - trace_f2fs_submit_page_mbio(fio->page, fio);
> return err;
> }
>
> @@ -752,7 +772,7 @@ static int __allocate_data_block(struct dnode_of_data *dn)
> set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version);
>
> allocate_data_block(sbi, NULL, dn->data_blkaddr, &dn->data_blkaddr,
> - &sum, CURSEG_WARM_DATA);
> + &sum, CURSEG_WARM_DATA, NULL, false);
> set_data_blkaddr(dn);
>
> /* update i_size */
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 9129a6229bc8..6b8e9f051aa2 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -802,8 +802,10 @@ struct f2fs_io_info {
> block_t old_blkaddr; /* old block address before Cow */
> struct page *page; /* page to be written */
> struct page *encrypted_page; /* encrypted page */
> + struct list_head list; /* serialize IOs */
> bool submitted; /* indicate IO submission */
> bool need_lock; /* indicate we need to lock cp_rwsem */
> + bool in_list; /* indicate fio is in io_list */
> };
>
> #define is_read_io(rw) ((rw) == READ)
> @@ -2274,7 +2276,8 @@ void f2fs_replace_block(struct f2fs_sb_info *sbi, struct dnode_of_data *dn,
> bool recover_newaddr);
> void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
> block_t old_blkaddr, block_t *new_blkaddr,
> - struct f2fs_summary *sum, int type);
> + struct f2fs_summary *sum, int type,
> + struct f2fs_io_info *fio, bool add_list);
> void f2fs_wait_on_page_writeback(struct page *page,
> enum page_type type, bool ordered);
> void f2fs_wait_on_encrypted_page_writeback(struct f2fs_sb_info *sbi,
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 8b267ca30926..ac2f74e40eea 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -590,6 +590,7 @@ static void move_encrypted_block(struct inode *inode, block_t bidx,
> .op = REQ_OP_READ,
> .op_flags = 0,
> .encrypted_page = NULL,
> + .in_list = false,
> };
> struct dnode_of_data dn;
> struct f2fs_summary sum;
> @@ -633,7 +634,7 @@ static void move_encrypted_block(struct inode *inode, block_t bidx,
> fio.new_blkaddr = fio.old_blkaddr = dn.data_blkaddr;
>
> allocate_data_block(fio.sbi, NULL, fio.old_blkaddr, &newaddr,
> - &sum, fio.seg_type);
> + &sum, fio.seg_type, NULL, false);
>
> fio.encrypted_page = pagecache_get_page(META_MAPPING(fio.sbi), newaddr,
> FGP_LOCK | FGP_CREAT, GFP_NOFS);
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index c047b5d8b9d3..d4975b8f4620 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2100,7 +2100,8 @@ static int __get_segment_type(struct page *page, enum page_type p_type)
>
> void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
> block_t old_blkaddr, block_t *new_blkaddr,
> - struct f2fs_summary *sum, int type)
> + struct f2fs_summary *sum, int type,
> + struct f2fs_io_info *fio, bool add_list)
> {
> struct sit_info *sit_i = SIT_I(sbi);
> struct curseg_info *curseg = CURSEG_I(sbi, type);
> @@ -2136,6 +2137,14 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
> if (page && IS_NODESEG(type))
> fill_node_footer_blkaddr(page, NEXT_FREE_BLKADDR(sbi, curseg));
>
> + if (add_list) {
> + INIT_LIST_HEAD(&fio->list);
> + fio->in_list = true;
> + spin_lock(&curseg->io_lock);
> + list_add_tail(&fio->list, &curseg->io_list);
> + spin_unlock(&curseg->io_lock);
> + }
> +
> mutex_unlock(&curseg->curseg_mutex);
> }
>
> @@ -2145,10 +2154,9 @@ static void do_write_page(struct f2fs_summary *sum, struct f2fs_io_info *fio)
>
> fio->seg_type = __get_segment_type(fio->page, fio->type);
>
> - mutex_lock(&CURSEG_I(fio->sbi, fio->seg_type)->wio_mutex);
> reallocate:
> allocate_data_block(fio->sbi, fio->page, fio->old_blkaddr,
> - &fio->new_blkaddr, sum, fio->seg_type);
> + &fio->new_blkaddr, sum, fio->seg_type, fio, true);
>
> /* writeout dirty page into bdev */
> err = f2fs_submit_page_mbio(fio);
> @@ -2156,8 +2164,6 @@ static void do_write_page(struct f2fs_summary *sum, struct f2fs_io_info *fio)
> fio->old_blkaddr = fio->new_blkaddr;
> goto reallocate;
> }
> -
> - mutex_unlock(&CURSEG_I(fio->sbi, fio->seg_type)->wio_mutex);
> }
>
> void write_meta_page(struct f2fs_sb_info *sbi, struct page *page)
> @@ -2171,6 +2177,7 @@ void write_meta_page(struct f2fs_sb_info *sbi, struct page *page)
> .new_blkaddr = page->index,
> .page = page,
> .encrypted_page = NULL,
> + .in_list = false,
> };
>
> if (unlikely(page->index >= MAIN_BLKADDR(sbi)))
> @@ -2978,7 +2985,8 @@ static int build_curseg(struct f2fs_sb_info *sbi)
> array[i].bio_info.sbi = sbi;
> array[i].bio_info.bio = NULL;
>
> - mutex_init(&array[i].wio_mutex);
> + spin_lock_init(&array[i].io_lock);
> + INIT_LIST_HEAD(&array[i].io_list);
> }
> return restore_curseg_summaries(sbi);
> }
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 701944b462cd..b6f5dffeaa61 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -283,7 +283,8 @@ struct curseg_info {
> struct rw_semaphore journal_rwsem; /* protect journal area */
> struct f2fs_journal *journal; /* cached journal info */
> struct f2fs_bio_info bio_info; /* for log bios */
> - struct mutex wio_mutex; /* serialize DATA/NODE IOs */
> + spinlock_t io_lock; /* serialize DATA/NODE IOs */
> + struct list_head io_list; /* tracking fios */
> unsigned char alloc_type; /* current allocation type */
> unsigned int segno; /* current segment number */
> unsigned short next_blkoff; /* next block offset to write */
> --
> 2.12.2.575.gb14f27f
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