f2fs: introduce a bio array for per-page write bios

The f2fs has three bio types, NODE, DATA, and META, and manages some data
structures per each bio types.

The codes are a little bit messy, thus, this patch introduces a bio array
which groups individual data structures as follows.

struct f2fs_bio_info {
	struct bio *bio;		/* bios to merge */
	sector_t last_block_in_bio;	/* last block number */
	struct mutex io_mutex;		/* mutex for bio */
};

struct f2fs_sb_info {
	...
	struct f2fs_bio_info write_io[NR_PAGE_TYPE];	/* for write bios */
	...
};

The code changes from this new data structure are trivial.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

3 files changed, 32 insertions, 26 deletions

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e9038bbeee9f..05f8fe1399ac 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -361,6 +361,12 @@ enum page_type {
         META_FLUSH,
 };
 
+struct f2fs_bio_info {
+        struct bio *bio;                /* bios to merge */
+        sector_t last_block_in_bio;     /* last block number */
+        struct mutex io_mutex;          /* mutex for bio */
+};
+
 struct f2fs_sb_info {
         struct super_block *sb;                 /* pointer to VFS super block */
         struct proc_dir_entry *s_proc;          /* proc entry */
@@ -374,9 +380,9 @@ struct f2fs_sb_info {
 
         /* for segment-related operations */
         struct f2fs_sm_info *sm_info;           /* segment manager */
-        struct bio *bio[NR_PAGE_TYPE];          /* bios to merge */
-        sector_t last_block_in_bio[NR_PAGE_TYPE];       /* last block number */
-        struct mutex write_mutex[NR_PAGE_TYPE]; /* mutex for writing IOs */
+
+        /* for bio operations */
+        struct f2fs_bio_info write_io[NR_PAGE_TYPE];    /* for write bios */
 
         /* for checkpoint */
         struct f2fs_checkpoint *ckpt;           /* raw checkpoint pointer */
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 68b8a2bdf6d8..38c1a89f54cc 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -836,65 +836,65 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
 {
         int rw = sync ? WRITE_SYNC : WRITE;
         enum page_type btype = PAGE_TYPE_OF_BIO(type);
-        struct bio *bio = sbi->bio[btype];
+        struct f2fs_bio_info *io = &sbi->write_io[btype];
         struct bio_private *p;
 
-        if (!bio)
+        if (!io->bio)
                 return;
 
-        sbi->bio[btype] = NULL;
-
         if (type >= META_FLUSH)
                 rw = WRITE_FLUSH_FUA;
         if (btype == META)
                 rw |= REQ_META;
 
-        p = bio->bi_private;
+        p = io->bio->bi_private;
         p->sbi = sbi;
-        bio->bi_end_io = f2fs_end_io_write;
+        io->bio->bi_end_io = f2fs_end_io_write;
 
-        trace_f2fs_do_submit_bio(sbi->sb, btype, sync, bio);
+        trace_f2fs_do_submit_bio(sbi->sb, btype, sync, io->bio);
 
         if (type == META_FLUSH) {
                 DECLARE_COMPLETION_ONSTACK(wait);
                 p->is_sync = true;
                 p->wait = &wait;
-                submit_bio(rw, bio);
+                submit_bio(rw, io->bio);
                 wait_for_completion(&wait);
         } else {
                 p->is_sync = false;
-                submit_bio(rw, bio);
+                submit_bio(rw, io->bio);
         }
+        io->bio = NULL;
 }
 
 void f2fs_submit_bio(struct f2fs_sb_info *sbi, enum page_type type, bool sync)
 {
-        enum page_type btype = PAGE_TYPE_OF_BIO(type);
+        struct f2fs_bio_info *io = &sbi->write_io[PAGE_TYPE_OF_BIO(type)];
 
-        if (!sbi->bio[btype])
+        if (!io->bio)
                 return;
 
-        mutex_lock(&sbi->write_mutex[btype]);
+        mutex_lock(&io->io_mutex);
         do_submit_bio(sbi, type, sync);
-        mutex_unlock(&sbi->write_mutex[btype]);
+        mutex_unlock(&io->io_mutex);
 }
 
 static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
                                 block_t blk_addr, enum page_type type)
 {
         struct block_device *bdev = sbi->sb->s_bdev;
+        struct f2fs_bio_info *io = &sbi->write_io[type];
         int bio_blocks;
 
         verify_block_addr(sbi, blk_addr);
 
-        mutex_lock(&sbi->write_mutex[type]);
+        mutex_lock(&io->io_mutex);
 
         inc_page_count(sbi, F2FS_WRITEBACK);
 
-        if (sbi->bio[type] && sbi->last_block_in_bio[type] != blk_addr - 1)
+        if (io->bio && io->last_block_in_bio != blk_addr - 1)
                 do_submit_bio(sbi, type, false);
 alloc_new:
-        if (sbi->bio[type] == NULL) {
+        if (io->bio == NULL) {
                 struct bio_private *priv;
 retry:
                 priv = kmalloc(sizeof(struct bio_private), GFP_NOFS);
@@ -904,9 +904,9 @@ retry:
                 }
 
                 bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
-                sbi->bio[type] = f2fs_bio_alloc(bdev, bio_blocks);
-                sbi->bio[type]->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
-                sbi->bio[type]->bi_private = priv;
+                io->bio = f2fs_bio_alloc(bdev, bio_blocks);
+                io->bio->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
+                io->bio->bi_private = priv;
                 /*
                  * The end_io will be assigned at the sumbission phase.
                  * Until then, let bio_add_page() merge consecutive IOs as much
@@ -914,15 +914,15 @@ retry:
                  */
         }
 
-        if (bio_add_page(sbi->bio[type], page, PAGE_CACHE_SIZE, 0) <
+        if (bio_add_page(io->bio, page, PAGE_CACHE_SIZE, 0) <
                                                         PAGE_CACHE_SIZE) {
                 do_submit_bio(sbi, type, false);
                 goto alloc_new;
         }
 
-        sbi->last_block_in_bio[type] = blk_addr;
+        io->last_block_in_bio = blk_addr;
 
-        mutex_unlock(&sbi->write_mutex[type]);
+        mutex_unlock(&io->io_mutex);
         trace_f2fs_submit_write_page(page, blk_addr, type);
 }
 
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index e194578b3594..8c677e958deb 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -879,7 +879,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
         spin_lock_init(&sbi->stat_lock);
 
         for (i = 0; i < NR_PAGE_TYPE; i++)
-                mutex_init(&sbi->write_mutex[i]);
+                mutex_init(&sbi->write_io[i].io_mutex);
 
         init_rwsem(&sbi->cp_rwsem);
         init_waitqueue_head(&sbi->cp_wait);