Re: [PATCH v2] f2fs: provide f2fs_balance_fs to __write_node_page

[Yunlong Song <yunlong.song@xxxxxxxxxx>]

Hi, Jay,
    Not sure yet, whether it is just the case or not, at least we 
strengthen f2fs_balance_fs in some
corner cases. And maybe there are still some corner cases which we have 
not considered yet. See
my new patch "provide f2fs_balance_fs to __write_data_page for dentry 
pages", which is reported
by Chao. This is another corner case.

On 2017/7/29 0:20, Jaegeuk Kim wrote:
> Hi Yunlong,
>
> On 07/27, Yunlong Song wrote:
> > v1->v2, fix some dead lock problems under some heavy load test
> So, does this patch resolve the previous GC problem?
>
> Thanks,
>
> > On 2017/7/27 20:11, Yunlong Song wrote:
> > > Let node writeback also do f2fs_balance_fs to ensure there are always enough free
> > > segments.
> > >
> > > Signed-off-by: Yunlong Song <yunlong.song@xxxxxxxxxx>
> > > ---
> > >    fs/f2fs/checkpoint.c |  2 +-
> > >    fs/f2fs/f2fs.h       |  2 +-
> > >    fs/f2fs/node.c       | 14 ++++++++------
> > >    3 files changed, 10 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> > > index 5b876f6..3c84a25 100644
> > > --- a/fs/f2fs/checkpoint.c
> > > +++ b/fs/f2fs/checkpoint.c
> > > @@ -1017,7 +1017,7 @@ static int block_operations(struct f2fs_sb_info *sbi)
> > >    	if (get_pages(sbi, F2FS_DIRTY_NODES)) {
> > >    		up_write(&sbi->node_write);
> > > -		err = sync_node_pages(sbi, &wbc);
> > > +		err = sync_node_pages(sbi, &wbc, false);
> > >    		if (err) {
> > >    			up_write(&sbi->node_change);
> > >    			f2fs_unlock_all(sbi);
> > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > > index 94a88b2..f69051b 100644
> > > --- a/fs/f2fs/f2fs.h
> > > +++ b/fs/f2fs/f2fs.h
> > > @@ -2293,7 +2293,7 @@ struct page *new_node_page(struct dnode_of_data *dn,
> > >    void move_node_page(struct page *node_page, int gc_type);
> > >    int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
> > >    			struct writeback_control *wbc, bool atomic);
> > > -int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc);
> > > +int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc, bool need);
> > >    void build_free_nids(struct f2fs_sb_info *sbi, bool sync, bool mount);
> > >    bool alloc_nid(struct f2fs_sb_info *sbi, nid_t *nid);
> > >    void alloc_nid_done(struct f2fs_sb_info *sbi, nid_t nid);
> > > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > > index d53fe62..210ec25 100644
> > > --- a/fs/f2fs/node.c
> > > +++ b/fs/f2fs/node.c
> > > @@ -1326,7 +1326,7 @@ static struct page *last_fsync_dnode(struct f2fs_sb_info *sbi, nid_t ino)
> > >    }
> > >    static int __write_node_page(struct page *page, bool atomic, bool *submitted,
> > > -				struct writeback_control *wbc)
> > > +				struct writeback_control *wbc, bool need)
> > >    {
> > >    	struct f2fs_sb_info *sbi = F2FS_P_SB(page);
> > >    	nid_t nid;
> > > @@ -1387,6 +1387,8 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
> > >    	}
> > >    	unlock_page(page);
> > > +	if (need)
> > > +		f2fs_balance_fs(sbi, false);
> > >    	if (unlikely(f2fs_cp_error(sbi))) {
> > >    		f2fs_submit_merged_write(sbi, NODE);
> > > @@ -1405,7 +1407,7 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
> > >    static int f2fs_write_node_page(struct page *page,
> > >    				struct writeback_control *wbc)
> > >    {
> > > -	return __write_node_page(page, false, NULL, wbc);
> > > +	return __write_node_page(page, false, NULL, wbc, false);
> > >    }
> > >    int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
> > > @@ -1493,7 +1495,7 @@ int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
> > >    			ret = __write_node_page(page, atomic &&
> > >    						page == last_page,
> > > -						&submitted, wbc);
> > > +						&submitted, wbc, true);
> > >    			if (ret) {
> > >    				unlock_page(page);
> > >    				f2fs_put_page(last_page, 0);
> > > @@ -1530,7 +1532,7 @@ int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
> > >    	return ret ? -EIO: 0;
> > >    }
> > > -int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc)
> > > +int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc, bool need)
> > >    {
> > >    	pgoff_t index, end;
> > >    	struct pagevec pvec;
> > > @@ -1608,7 +1610,7 @@ int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc)
> > >    			set_fsync_mark(page, 0);
> > >    			set_dentry_mark(page, 0);
> > > -			ret = __write_node_page(page, false, &submitted, wbc);
> > > +			ret = __write_node_page(page, false, &submitted, wbc, need);
> > >    			if (ret)
> > >    				unlock_page(page);
> > >    			else if (submitted)
> > > @@ -1697,7 +1699,7 @@ static int f2fs_write_node_pages(struct address_space *mapping,
> > >    	diff = nr_pages_to_write(sbi, NODE, wbc);
> > >    	wbc->sync_mode = WB_SYNC_NONE;
> > >    	blk_start_plug(&plug);
> > > -	sync_node_pages(sbi, wbc);
> > > +	sync_node_pages(sbi, wbc, true);
> > >    	blk_finish_plug(&plug);
> > >    	wbc->nr_to_write = max((long)0, wbc->nr_to_write - diff);
> > >    	return 0;
> > --
> > Thanks,
> > Yunlong Song
> .

--
Thanks,
Yunlong Song