[PATCH 3/3] f2fs: introduce io_list for serialize data/node IOs

[Chao Yu]

From: Chao Yu <yuchao0@xxxxxxxxxx>

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.

Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
---
 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