Re: [f2fs-dev] [PATCH 13/13] f2fs: handle EIO not to break fs consistency

[Jaegeuk Kim]

On Wed, Aug 20, 2014 at 06:35:18PM +0800, Chao Yu wrote:
> Hi Jaegeuk,
> 
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx]
> > Sent: Wednesday, August 13, 2014 3:49 AM
> > To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> > Cc: Jaegeuk Kim
> > Subject: [f2fs-dev] [PATCH 13/13] f2fs: handle EIO not to break fs consistency
> > 
> > There are two rules when EIO is occurred.
> > 1. don't write any checkpoint data to preserve the previous checkpoint
> > 2. don't lose the cached data/node/meta pages
> > 
> > So, at first, this patch adds set_page_dirty in f2fs_write_end_io's failure.
> > Then, writing checkpoint/dentry/node blocks is not allowed.
> 
> do_checkpoint()
> 	/* wait for previous submitted node/meta pages writeback */
> 	wait_on_all_pages_writeback(sbi);
> 
> 	if (unlikely(f2fs_cp_error(sbi)))
> 		return;
> add here to prevent unneeded syncing for meta/node pages.

Well, there is one below. But it's not a big deal to change the location.

> 
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> > ---
> >  fs/f2fs/checkpoint.c | 47 +++++++++++++++++++++++++++++++++--------------
> >  fs/f2fs/data.c       | 10 +++++++++-
> >  fs/f2fs/f2fs.h       |  1 +
> >  fs/f2fs/node.c       |  2 ++
> >  fs/f2fs/super.c      |  3 +++
> >  5 files changed, 48 insertions(+), 15 deletions(-)
> > 
> > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> > index d074e27..b365c64 100644
> > --- a/fs/f2fs/checkpoint.c
> > +++ b/fs/f2fs/checkpoint.c
> > @@ -160,14 +160,11 @@ static int f2fs_write_meta_page(struct page *page,
> >  		goto redirty_out;
> >  	if (wbc->for_reclaim)
> >  		goto redirty_out;
> > -
> > -	/* Should not write any meta pages, if any IO error was occurred */
> >  	if (unlikely(f2fs_cp_error(sbi)))
> > -		goto no_write;
> > +		goto redirty_out;
> > 
> >  	f2fs_wait_on_page_writeback(page, META);
> >  	write_meta_page(sbi, page);
> > -no_write:
> >  	dec_page_count(sbi, F2FS_DIRTY_META);
> >  	unlock_page(page);
> >  	return 0;
> > @@ -348,7 +345,7 @@ bool exist_written_data(struct f2fs_sb_info *sbi, nid_t ino, int mode)
> >  	return e ? true : false;
> >  }
> > 
> > -static void release_dirty_inode(struct f2fs_sb_info *sbi)
> > +void release_dirty_inode(struct f2fs_sb_info *sbi)
> >  {
> >  	struct ino_entry *e, *tmp;
> >  	int i;
> > @@ -737,7 +734,7 @@ retry:
> >  /*
> >   * Freeze all the FS-operations for checkpoint.
> >   */
> > -static void block_operations(struct f2fs_sb_info *sbi)
> > +static int block_operations(struct f2fs_sb_info *sbi)
> >  {
> >  	struct writeback_control wbc = {
> >  		.sync_mode = WB_SYNC_ALL,
> > @@ -745,6 +742,7 @@ static void block_operations(struct f2fs_sb_info *sbi)
> >  		.for_reclaim = 0,
> >  	};
> >  	struct blk_plug plug;
> > +	int err = 0;
> > 
> >  	blk_start_plug(&plug);
> > 
> > @@ -754,6 +752,10 @@ retry_flush_dents:
> >  	if (get_pages(sbi, F2FS_DIRTY_DENTS)) {
> >  		f2fs_unlock_all(sbi);
> >  		sync_dirty_dir_inodes(sbi);
> > +		if (unlikely(f2fs_cp_error(sbi))) {
> > +			err = -EIO;
> > +			goto out;
> > +		}
> >  		goto retry_flush_dents;
> >  	}
> > 
> > @@ -767,9 +769,16 @@ retry_flush_nodes:
> >  	if (get_pages(sbi, F2FS_DIRTY_NODES)) {
> >  		up_write(&sbi->node_write);
> >  		sync_node_pages(sbi, 0, &wbc);
> > +		if (unlikely(f2fs_cp_error(sbi))) {
> > +			f2fs_unlock_all(sbi);
> > +			err = -EIO;
> > +			goto out;
> > +		}
> >  		goto retry_flush_nodes;
> >  	}
> > +out:
> >  	blk_finish_plug(&plug);
> > +	return err;
> >  }
> > 
> >  static void unblock_operations(struct f2fs_sb_info *sbi)
> > @@ -813,8 +822,11 @@ static void do_checkpoint(struct f2fs_sb_info *sbi, bool is_umount)
> >  	discard_next_dnode(sbi, NEXT_FREE_BLKADDR(sbi, curseg));
> > 
> >  	/* Flush all the NAT/SIT pages */
> > -	while (get_pages(sbi, F2FS_DIRTY_META))
> > +	while (get_pages(sbi, F2FS_DIRTY_META)) {
> >  		sync_meta_pages(sbi, META, LONG_MAX);
> > +		if (unlikely(f2fs_cp_error(sbi)))
> > +			return;
> > +	}
> > 
> >  	next_free_nid(sbi, &last_nid);
> > 
> > @@ -931,14 +943,19 @@ static void do_checkpoint(struct f2fs_sb_info *sbi, bool is_umount)
> >  	sbi->last_valid_block_count = sbi->total_valid_block_count;
> >  	sbi->alloc_valid_block_count = 0;
> > 
> > +	if (unlikely(f2fs_cp_error(sbi)))
> > +		return;
> > +
> >  	/* Here, we only have one bio having CP pack */
> >  	sync_meta_pages(sbi, META_FLUSH, LONG_MAX);
> > 
> > -	if (!f2fs_cp_error(sbi)) {
> > -		clear_prefree_segments(sbi);
> > -		release_dirty_inode(sbi);
> > -		F2FS_RESET_SB_DIRT(sbi);
> > -	}
> > +	release_dirty_inode(sbi);
> > +
> > +	if (unlikely(f2fs_cp_error(sbi)))
> > +		return;
> > +
> > +	clear_prefree_segments(sbi);
> > +	F2FS_RESET_SB_DIRT(sbi);
> >  }
> > 
> >  /*
> > @@ -955,8 +972,10 @@ void write_checkpoint(struct f2fs_sb_info *sbi, bool is_umount)
> > 
> >  	if (!sbi->s_dirty)
> >  		goto out;
> > -
> > -	block_operations(sbi);
> > +	if (unlikely(f2fs_cp_error(sbi)))
> > +		goto out;
> > +	if (block_operations(sbi))
> > +		goto out;
> > 
> >  	trace_f2fs_write_checkpoint(sbi->sb, is_umount, "finish block_ops");
> > 
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index ac3ccc2..68834e2 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -53,7 +53,7 @@ static void f2fs_write_end_io(struct bio *bio, int err)
> >  		struct page *page = bvec->bv_page;
> > 
> >  		if (unlikely(err)) {
> > -			SetPageError(page);
> > +			set_page_dirty(page);
> >  			set_bit(AS_EIO, &page->mapping->flags);
> >  			f2fs_stop_checkpoint(sbi);
> >  		}
> > @@ -836,10 +836,18 @@ write:
> > 
> >  	/* Dentry blocks are controlled by checkpoint */
> >  	if (S_ISDIR(inode->i_mode)) {
> > +		if (unlikely(f2fs_cp_error(sbi)))
> > +			goto redirty_out;
> >  		err = do_write_data_page(page, &fio);
> >  		goto done;
> >  	}
> > 
> > +	if (unlikely(f2fs_cp_error(sbi))) {
> > +		SetPageError(page);
> > +		unlock_page(page);
> > +		return 0;
> 
> Without redirtying it, we may lose cached page here which against the
> second rule.

Ya, I need to change the description for this. If we call redirty_out for all
the dirty data pages, kworker cannot finish the job, resulting in 98% of cpu to
retry flushes. This can be found through xfstests/019.
So, for that reason, we need to drop user data for now.
It might be worth to do something to support removable devices later.

Thanks,

> 
> Thanks,
> Yu
> 
> 
> > +	}
> > +
> >  	if (!wbc->for_reclaim)
> >  		need_balance_fs = true;
> >  	else if (has_not_enough_free_secs(sbi, 0))
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index 46ceb88..2d009ae 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -1267,6 +1267,7 @@ int ra_meta_pages(struct f2fs_sb_info *, int, int, int);
> >  long sync_meta_pages(struct f2fs_sb_info *, enum page_type, long);
> >  void add_dirty_inode(struct f2fs_sb_info *, nid_t, int type);
> >  void remove_dirty_inode(struct f2fs_sb_info *, nid_t, int type);
> > +void release_dirty_inode(struct f2fs_sb_info *);
> >  bool exist_written_data(struct f2fs_sb_info *, nid_t, int);
> >  int acquire_orphan_inode(struct f2fs_sb_info *);
> >  void release_orphan_inode(struct f2fs_sb_info *);
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > index 9f126f8..d2f7842 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -1215,6 +1215,8 @@ static int f2fs_write_node_page(struct page *page,
> > 
> >  	if (unlikely(sbi->por_doing))
> >  		goto redirty_out;
> > +	if (unlikely(f2fs_cp_error(sbi)))
> > +		goto redirty_out;
> > 
> >  	f2fs_wait_on_page_writeback(page, NODE);
> > 
> > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > index c4f90cd..c999d67 100644
> > --- a/fs/f2fs/super.c
> > +++ b/fs/f2fs/super.c
> > @@ -435,6 +435,9 @@ static void f2fs_put_super(struct super_block *sb)
> >  	if (sbi->s_dirty)
> >  		write_checkpoint(sbi, true);
> > 
> > +	/* EIO will skip do checkpoint, so here we need to release this */
> > +	release_dirty_inode(sbi);
> > +
> >  	iput(sbi->node_inode);
> >  	iput(sbi->meta_inode);
> > 
> > --
> > 1.8.5.2 (Apple Git-48)
> > 
> > 
> > ------------------------------------------------------------------------------
> > _______________________________________________
> > Linux-f2fs-devel mailing list
> > Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
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