Commit c718379b authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: give a chance to merge IOs by IO scheduler 



Previously, background GC submits many 4KB read requests to load victim blocks
and/or its (i)node blocks.

...
f2fs_gc : f2fs_readpage: ino = 1, page_index = 0xb61, blkaddr = 0x3b964ed
f2fs_gc : block_rq_complete: 8,16 R () 499854968 + 8 [0]
f2fs_gc : f2fs_readpage: ino = 1, page_index = 0xb6f, blkaddr = 0x3b964ee
f2fs_gc : block_rq_complete: 8,16 R () 499854976 + 8 [0]
f2fs_gc : f2fs_readpage: ino = 1, page_index = 0xb79, blkaddr = 0x3b964ef
f2fs_gc : block_rq_complete: 8,16 R () 499854984 + 8 [0]
...

However, by the fact that many IOs are sequential, we can give a chance to merge
the IOs by IO scheduler.
In order to do that, let's use blk_plug.

...
f2fs_gc : f2fs_iget: ino = 143
f2fs_gc : f2fs_readpage: ino = 143, page_index = 0x1c6, blkaddr = 0x2e6ee
f2fs_gc : f2fs_iget: ino = 143
f2fs_gc : f2fs_readpage: ino = 143, page_index = 0x1c7, blkaddr = 0x2e6ef
<idle> : block_rq_complete: 8,16 R () 1519616 + 8 [0]
<idle> : block_rq_complete: 8,16 R () 1519848 + 8 [0]
<idle> : block_rq_complete: 8,16 R () 1520432 + 96 [0]
<idle> : block_rq_complete: 8,16 R () 1520536 + 104 [0]
<idle> : block_rq_complete: 8,16 R () 1521008 + 112 [0]
<idle> : block_rq_complete: 8,16 R () 1521440 + 152 [0]
<idle> : block_rq_complete: 8,16 R () 1521688 + 144 [0]
<idle> : block_rq_complete: 8,16 R () 1522128 + 192 [0]
<idle> : block_rq_complete: 8,16 R () 1523256 + 328 [0]
...

Note that this issue should be addressed in checkpoint, and some readahead
flows too.

Reviewed-by: default avatarNamjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk.kim@samsung.com>
parent 6cb968d9

fs/f2fs/checkpoint.c

+5 −0
Original line number Diff line number Diff line
@@ -549,6 +549,10 @@ static void block_operations(struct f2fs_sb_info *sbi) 
		.nr_to_write = LONG_MAX,

		.for_reclaim = 0,

	};

	struct blk_plug plug;



	blk_start_plug(&plug);



retry_flush_dents:

	mutex_lock_all(sbi);
@@ -571,6 +575,7 @@ static void block_operations(struct f2fs_sb_info *sbi) 
		sync_node_pages(sbi, 0, &wbc);

		goto retry_flush_nodes;

	}

	blk_finish_plug(&plug);

}



static void unblock_operations(struct f2fs_sb_info *sbi)

fs/f2fs/data.c

+9 −6
Original line number Diff line number Diff line
@@ -172,7 +172,7 @@ void update_extent_cache(block_t blk_addr, struct dnode_of_data *dn) 
	return;

}



struct page *find_data_page(struct inode *inode, pgoff_t index)

struct page *find_data_page(struct inode *inode, pgoff_t index, bool sync)

{

	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);

	struct address_space *mapping = inode->i_mapping;
@@ -207,12 +207,15 @@ struct page *find_data_page(struct inode *inode, pgoff_t index) 
		return page;

	}



	err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);

	err = f2fs_readpage(sbi, page, dn.data_blkaddr,

					sync ? READ_SYNC : READA);

	if (sync) {

		wait_on_page_locked(page);

		if (!PageUptodate(page)) {

			f2fs_put_page(page, 0);

			return ERR_PTR(-EIO);

		}

	}

	return page;

}

fs/f2fs/dir.c

+1 −1
Original line number Diff line number Diff line
@@ -148,7 +148,7 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir, 


	for (; bidx < end_block; bidx++) {

		/* no need to allocate new dentry pages to all the indices */

		dentry_page = find_data_page(dir, bidx);

		dentry_page = find_data_page(dir, bidx, true);

		if (IS_ERR(dentry_page)) {

			room = true;

			continue;

fs/f2fs/f2fs.h

+1 −1
Original line number Diff line number Diff line
@@ -1023,7 +1023,7 @@ void destroy_checkpoint_caches(void); 
 */

int reserve_new_block(struct dnode_of_data *);

void update_extent_cache(block_t, struct dnode_of_data *);

struct page *find_data_page(struct inode *, pgoff_t);

struct page *find_data_page(struct inode *, pgoff_t, bool);

struct page *get_lock_data_page(struct inode *, pgoff_t);

struct page *get_new_data_page(struct inode *, pgoff_t, bool);

int f2fs_readpage(struct f2fs_sb_info *, struct page *, block_t, int);

fs/f2fs/file.c

+1 −1
Original line number Diff line number Diff line
@@ -212,7 +212,7 @@ static void truncate_partial_data_page(struct inode *inode, u64 from) 
	if (!offset)

		return;



	page = find_data_page(inode, from >> PAGE_CACHE_SHIFT);

	page = find_data_page(inode, from >> PAGE_CACHE_SHIFT, false);

	if (IS_ERR(page))

		return;