Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 25 Sep 2018 20:32:26 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     Chao Yu <chao@kernel.org>, linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] f2fs: submit cached bio to avoid endless PageWriteback
Message-ID: <20180926033226.GH3829@jaegeuk-macbookpro.roam.corp.google.com>
References: <3ca1e04f-0929-2ab3-2112-4fa22915be50@huawei.com>
 <20180918013743.GE79604@jaegeuk-macbookpro.roam.corp.google.com>
 <8b1571fa-ef41-4ab3-187c-d6caf7a2ebe1@huawei.com>
 <20180918020226.GA83471@jaegeuk-macbookpro.roam.corp.google.com>
 <acb91226-bb83-3d7f-3ac8-db7a3ee24172@huawei.com>
 <ab15ea97-0ad8-ce85-3f3c-197ecc0c4e16@kernel.org>
 <20180926002033.GB3829@jaegeuk-macbookpro.roam.corp.google.com>
 <f230fe9c-9560-1f16-178b-810b54461d1f@huawei.com>
 <20180926014221.GD3829@jaegeuk-macbookpro.roam.corp.google.com>
 <8a3256b9-e198-e0e1-6dea-4ac5d06e21b1@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <8a3256b9-e198-e0e1-6dea-4ac5d06e21b1@huawei.com>
User-Agent: Mutt/1.8.2 (2017-04-18)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 09/26, Chao Yu wrote:
> On 2018/9/26 9:42, Jaegeuk Kim wrote:
> > On 09/26, Chao Yu wrote:
> >> On 2018/9/26 8:20, Jaegeuk Kim wrote:
> >>> On 09/21, Chao Yu wrote:
> >>>> On 2018/9/18 10:14, Chao Yu wrote:
> >>>>> On 2018/9/18 10:02, Jaegeuk Kim wrote:
> >>>>>> On 09/18, Chao Yu wrote:
> >>>>>>> On 2018/9/18 9:37, Jaegeuk Kim wrote:
> >>>>>>>> On 09/18, Chao Yu wrote:
> >>>>>>>>> On 2018/9/18 9:04, Jaegeuk Kim wrote:
> >>>>>>>>>> On 09/13, Chao Yu wrote:
> >>>>>>>>>>> From: Chao Yu <yuchao0@huawei.com>
> >>>>>>>>>>>
> >>>>>>>>>>> When migrating encrypted block from background GC thread, we only add
> >>>>>>>>>>> them into f2fs inner bio cache, but forget to submit the cached bio, it
> >>>>>>>>>>> may cause potential deadlock when we are waiting page writebacked, fix
> >>>>>>>>>>> it.
> >>>>>>>>>>>
> >>>>>>>>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> >>>>>>>>>>> ---
> >>>>>>>>>>> v3:
> >>>>>>>>>>> clean up codes suggested by Jaegeuk.
> >>>>>>>>>>>  fs/f2fs/f2fs.h |  2 +-
> >>>>>>>>>>>  fs/f2fs/gc.c   | 71 +++++++++++++++++++++++++++++++++++---------------
> >>>>>>>>>>>  fs/f2fs/node.c | 13 ++++++---
> >>>>>>>>>>>  3 files changed, 61 insertions(+), 25 deletions(-)
> >>>>>>>>>>>
> >>>>>>>>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >>>>>>>>>>> index b676b82312e0..917b2ca76aac 100644
> >>>>>>>>>>> --- a/fs/f2fs/f2fs.h
> >>>>>>>>>>> +++ b/fs/f2fs/f2fs.h
> >>>>>>>>>>> @@ -2869,7 +2869,7 @@ struct page *f2fs_new_node_page(struct dnode_of_data *dn, unsigned int ofs);
> >>>>>>>>>>>  void f2fs_ra_node_page(struct f2fs_sb_info *sbi, nid_t nid);
> >>>>>>>>>>>  struct page *f2fs_get_node_page(struct f2fs_sb_info *sbi, pgoff_t nid);
> >>>>>>>>>>>  struct page *f2fs_get_node_page_ra(struct page *parent, int start);
> >>>>>>>>>>> -void f2fs_move_node_page(struct page *node_page, int gc_type);
> >>>>>>>>>>> +int f2fs_move_node_page(struct page *node_page, int gc_type);
> >>>>>>>>>>>  int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
> >>>>>>>>>>>  			struct writeback_control *wbc, bool atomic,
> >>>>>>>>>>>  			unsigned int *seq_id);
> >>>>>>>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> >>>>>>>>>>> index a4c1a419611d..f57622cfe058 100644
> >>>>>>>>>>> --- a/fs/f2fs/gc.c
> >>>>>>>>>>> +++ b/fs/f2fs/gc.c
> >>>>>>>>>>> @@ -461,7 +461,7 @@ static int check_valid_map(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>   * On validity, copy that node with cold status, otherwise (invalid node)
> >>>>>>>>>>>   * ignore that.
> >>>>>>>>>>>   */
> >>>>>>>>>>> -static void gc_node_segment(struct f2fs_sb_info *sbi,
> >>>>>>>>>>> +static int gc_node_segment(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>  		struct f2fs_summary *sum, unsigned int segno, int gc_type)
> >>>>>>>>>>>  {
> >>>>>>>>>>>  	struct f2fs_summary *entry;
> >>>>>>>>>>> @@ -469,6 +469,7 @@ static void gc_node_segment(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>  	int off;
> >>>>>>>>>>>  	int phase = 0;
> >>>>>>>>>>>  	bool fggc = (gc_type == FG_GC);
> >>>>>>>>>>> +	int submitted = 0;
> >>>>>>>>>>>  
> >>>>>>>>>>>  	start_addr = START_BLOCK(sbi, segno);
> >>>>>>>>>>>  
> >>>>>>>>>>> @@ -482,10 +483,11 @@ static void gc_node_segment(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>  		nid_t nid = le32_to_cpu(entry->nid);
> >>>>>>>>>>>  		struct page *node_page;
> >>>>>>>>>>>  		struct node_info ni;
> >>>>>>>>>>> +		int err;
> >>>>>>>>>>>  
> >>>>>>>>>>>  		/* stop BG_GC if there is not enough free sections. */
> >>>>>>>>>>>  		if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0))
> >>>>>>>>>>> -			return;
> >>>>>>>>>>> +			return submitted;
> >>>>>>>>>>>  
> >>>>>>>>>>>  		if (check_valid_map(sbi, segno, off) == 0)
> >>>>>>>>>>>  			continue;
> >>>>>>>>>>> @@ -522,7 +524,9 @@ static void gc_node_segment(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>  			continue;
> >>>>>>>>>>>  		}
> >>>>>>>>>>>  
> >>>>>>>>>>> -		f2fs_move_node_page(node_page, gc_type);
> >>>>>>>>>>> +		err = f2fs_move_node_page(node_page, gc_type);
> >>>>>>>>>>> +		if (!err && gc_type == FG_GC)
> >>>>>>>>>>> +			submitted++;
> >>>>>>>>>>>  		stat_inc_node_blk_count(sbi, 1, gc_type);
> >>>>>>>>>>>  	}
> >>>>>>>>>>>  
> >>>>>>>>>>> @@ -531,6 +535,7 @@ static void gc_node_segment(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>  
> >>>>>>>>>>>  	if (fggc)
> >>>>>>>>>>>  		atomic_dec(&sbi->wb_sync_req[NODE]);
> >>>>>>>>>>> +	return submitted;
> >>>>>>>>>>>  }
> >>>>>>>>>>>  
> >>>>>>>>>>>  /*
> >>>>>>>>>>> @@ -666,7 +671,7 @@ static int ra_data_block(struct inode *inode, pgoff_t index)
> >>>>>>>>>>>   * Move data block via META_MAPPING while keeping locked data page.
> >>>>>>>>>>>   * This can be used to move blocks, aka LBAs, directly on disk.
> >>>>>>>>>>>   */
> >>>>>>>>>>> -static void move_data_block(struct inode *inode, block_t bidx,
> >>>>>>>>>>> +static int move_data_block(struct inode *inode, block_t bidx,
> >>>>>>>>>>>  				int gc_type, unsigned int segno, int off)
> >>>>>>>>>>
> >>>>>>>>>> We don't need to submit IOs in this case.
> >>>>>>>>>
> >>>>>>>>> Actually, previously, we missed to submit IOs for encrypted block only in
> >>>>>>>>> BGGC, so we fix to submit for this case, all other codes are cleanups. Right?
> >>>>>>>>
> >>>>>>>> The move_data_block migrates encrypted blocks all the time with meta page IOs.
> >>>>>>>> I don't know what you're saying about BGGC.
> >>>>>>>
> >>>>>>> In move_data_block(), we use f2fs_submit_page_write() to add encrypted page
> >>>>>>> in to sbi->write_io[META].bio cache, so before exit GC, we need to submit
> >>>>>>> this cache by f2fs_submit_merged_write(), otherwise bio with encrypted page
> >>>>>>> will be cached in sbi->write_io[META].bio for long time, since we only
> >>>>>>> submmit this bio cache in foreground GC.
> >>>>>>>
> >>>>>>> if (gc_type == FG_GC)
> >>>>>>> 	f2fs_submit_merged_write(sbi,
> >>>>>>> 				(type == SUM_TYPE_NODE) ? NODE : DATA);
> >>>>>>
> >>>>>> Does this issue pending META IOs? I think META won't block any NODE/DATA
> >>>>>> pages. Moreover checkpoint or reading the moved block make the IOs be flushed,
> >>>>>> so it doesn't hurt the consistency.
> >>>>
> >>>> It may cause long latency before someone flushes the meta IO, how about flushing
> >>>> IO like other flows, like writepages?
> >>>>
> >>>> Or is there any benefit that we still cache meta IO after GC?
> >>>>
> >>>>>
> >>>>> I just guess below endless waiting for page writeback is cased by this case
> >>>>
> >>>> Any thoughts?
> >>>
> >>> I'm waiting for the previous reported issue. Do we have this in products?
> >>
> >> I didn't see such stack in products.
> >>
> >> BTW, I added one patch in my tree, although this patch is not correct now
> >> since it is missing to submit bio in some cases, it can easily reproduce
> >> such stack, so I guess there is still at least one place we didn't submit
> >> bio correctly.
> > 
> > How can we easily reproduce this? Why do we need to submit all of them?
> 
> In f2fs_write_cache_pages(), if we only check page with last_idx is not enough?
> 
> 1. cache page (idx = 1) in cold data bio cache
> 2. cache page (idx = 2) in warm data bio cache and submitted bio cache
> 3. f2fs_submit_merged_write_cond tries to check page (idx = 2), but this
> page is not in bio cache, so we missed to submit code data bio cache, right?

Oh, do we need to check temp when submit_bio? e.g., if it's different temp,
we can submit the previous fio.

> 
> Thanks,
> 
> > 
> >>
> >> https://git.kernel.org/pub/scm/linux/kernel/git/chao/linux.git/commit/?h=f2fs-dev&id=2ca666658fc1958ab176030d435efa2ce325aa52
> >>
> >> Thanks,
> >>
> >>>
> >>>>
> >>>>>
> >>>>> -000|__switch_to()
> >>>>>
> >>>>> -001|__schedule()
> >>>>>
> >>>>> -002|need_resched(inline)
> >>>>>
> >>>>> -002|schedule()
> >>>>>
> >>>>> -003|schedule_timeout()
> >>>>>
> >>>>> -004|get_current(inline)
> >>>>>
> >>>>> -004|io_schedule_timeout()
> >>>>>
> >>>>> -005|bit_wait_io()
> >>>>>
> >>>>> -006|__wait_on_bit()
> >>>>>
> >>>>> -007|wait_on_page_bit()
> >>>>>
> >>>>> -008|PageWriteback(inline)
> >>>>>
> >>>>> -008|wait_on_page_writeback(inline)
> >>>>>
> >>>>> -008|__filemap_fdatawait_range()
> >>>>>
> >>>>> -009|filemap_fdatawait_keep_errors()
> >>>>>
> >>>>> -010|sync_inodes_sb()
> >>>>>
> >>>>> -011|__sync_filesystem(inline)
> >>>>>
> >>>>> -011|sync_filesystem()
> >>>>>
> >>>>> -012|generic_shutdown_super()
> >>>>>
> >>>>> -013|kill_block_super()
> >>>>>
> >>>>> -014|kill_f2fs_super()
> >>>>>
> >>>>> -015|deactivate_locked_super()
> >>>>>
> >>>>> -016|deactivate_super()
> >>>>>
> >>>>> -017|mnt_free_id(inline)
> >>>>>
> >>>>> -017|cleanup_mnt()
> >>>>>
> >>>>> -018|__cleanup_mnt()
> >>>>>
> >>>>> -019|task_work_run()
> >>>>>
> >>>>> -020|do_notify_resume()
> >>>>>
> >>>>> -021|work_pending(asm)
> >>>>>
> >>>>> -->|exception
> >>>>>
> >>>>> -022|NUX:0x539E58(asm)
> >>>>>
> >>>>> ---|end of frame
> >>>>>
> >>>>>>
> >>>>>>>
> >>>>>>>>
> >>>>>>>>>
> >>>>>>>>> Thanks,
> >>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>>  {
> >>>>>>>>>>>  	struct f2fs_io_info fio = {
> >>>>>>>>>>> @@ -685,25 +690,29 @@ static void move_data_block(struct inode *inode, block_t bidx,
> >>>>>>>>>>>  	struct node_info ni;
> >>>>>>>>>>>  	struct page *page, *mpage;
> >>>>>>>>>>>  	block_t newaddr;
> >>>>>>>>>>> -	int err;
> >>>>>>>>>>> +	int err = 0;
> >>>>>>>>>>>  	bool lfs_mode = test_opt(fio.sbi, LFS);
> >>>>>>>>>>>  
> >>>>>>>>>>>  	/* do not read out */
> >>>>>>>>>>>  	page = f2fs_grab_cache_page(inode->i_mapping, bidx, false);
> >>>>>>>>>>>  	if (!page)
> >>>>>>>>>>> -		return;
> >>>>>>>>>>> +		return -ENOMEM;
> >>>>>>>>>>>  
> >>>>>>>>>>> -	if (!check_valid_map(F2FS_I_SB(inode), segno, off))
> >>>>>>>>>>> +	if (!check_valid_map(F2FS_I_SB(inode), segno, off)) {
> >>>>>>>>>>> +		err = -ENOENT;
> >>>>>>>>>>>  		goto out;
> >>>>>>>>>>> +	}
> >>>>>>>>>>>  
> >>>>>>>>>>>  	if (f2fs_is_atomic_file(inode)) {
> >>>>>>>>>>>  		F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC]++;
> >>>>>>>>>>>  		F2FS_I_SB(inode)->skipped_atomic_files[gc_type]++;
> >>>>>>>>>>> +		err = -EAGAIN;
> >>>>>>>>>>>  		goto out;
> >>>>>>>>>>>  	}
> >>>>>>>>>>>  
> >>>>>>>>>>>  	if (f2fs_is_pinned_file(inode)) {
> >>>>>>>>>>>  		f2fs_pin_file_control(inode, true);
> >>>>>>>>>>> +		err = -EAGAIN;
> >>>>>>>>>>>  		goto out;
> >>>>>>>>>>>  	}
> >>>>>>>>>>>  
> >>>>>>>>>>> @@ -714,6 +723,7 @@ static void move_data_block(struct inode *inode, block_t bidx,
> >>>>>>>>>>>  
> >>>>>>>>>>>  	if (unlikely(dn.data_blkaddr == NULL_ADDR)) {
> >>>>>>>>>>>  		ClearPageUptodate(page);
> >>>>>>>>>>> +		err = -ENOENT;
> >>>>>>>>>>>  		goto put_out;
> >>>>>>>>>>>  	}
> >>>>>>>>>>>  
> >>>>>>>>>>> @@ -796,6 +806,7 @@ static void move_data_block(struct inode *inode, block_t bidx,
> >>>>>>>>>>>  	fio.new_blkaddr = newaddr;
> >>>>>>>>>>>  	f2fs_submit_page_write(&fio);
> >>>>>>>>>>>  	if (fio.retry) {
> >>>>>>>>>>> +		err = -EAGAIN;
> >>>>>>>>>>>  		if (PageWriteback(fio.encrypted_page))
> >>>>>>>>>>>  			end_page_writeback(fio.encrypted_page);
> >>>>>>>>>>>  		goto put_page_out;
> >>>>>>>>>>> @@ -819,34 +830,42 @@ static void move_data_block(struct inode *inode, block_t bidx,
> >>>>>>>>>>>  	f2fs_put_dnode(&dn);
> >>>>>>>>>>>  out:
> >>>>>>>>>>>  	f2fs_put_page(page, 1);
> >>>>>>>>>>> +	return err;
> >>>>>>>>>>>  }
> >>>>>>>>>>>  
> >>>>>>>>>>> -static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
> >>>>>>>>>>> +static int move_data_page(struct inode *inode, block_t bidx, int gc_type,
> >>>>>>>>>>>  							unsigned int segno, int off)
> >>>>>>>>>>>  {
> >>>>>>>>>>>  	struct page *page;
> >>>>>>>>>>> +	int err = 0;
> >>>>>>>>>>>  
> >>>>>>>>>>>  	page = f2fs_get_lock_data_page(inode, bidx, true);
> >>>>>>>>>>>  	if (IS_ERR(page))
> >>>>>>>>>>> -		return;
> >>>>>>>>>>> +		return PTR_ERR(page);
> >>>>>>>>>>>  
> >>>>>>>>>>> -	if (!check_valid_map(F2FS_I_SB(inode), segno, off))
> >>>>>>>>>>> +	if (!check_valid_map(F2FS_I_SB(inode), segno, off)) {
> >>>>>>>>>>> +		err = -ENOENT;
> >>>>>>>>>>>  		goto out;
> >>>>>>>>>>> +	}
> >>>>>>>>>>>  
> >>>>>>>>>>>  	if (f2fs_is_atomic_file(inode)) {
> >>>>>>>>>>>  		F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC]++;
> >>>>>>>>>>>  		F2FS_I_SB(inode)->skipped_atomic_files[gc_type]++;
> >>>>>>>>>>> +		err = -EAGAIN;
> >>>>>>>>>>>  		goto out;
> >>>>>>>>>>>  	}
> >>>>>>>>>>>  	if (f2fs_is_pinned_file(inode)) {
> >>>>>>>>>>>  		if (gc_type == FG_GC)
> >>>>>>>>>>>  			f2fs_pin_file_control(inode, true);
> >>>>>>>>>>> +		err = -EAGAIN;
> >>>>>>>>>>>  		goto out;
> >>>>>>>>>>>  	}
> >>>>>>>>>>>  
> >>>>>>>>>>>  	if (gc_type == BG_GC) {
> >>>>>>>>>>> -		if (PageWriteback(page))
> >>>>>>>>>>> +		if (PageWriteback(page)) {
> >>>>>>>>>>> +			err = -EAGAIN;
> >>>>>>>>>>>  			goto out;
> >>>>>>>>>>> +		}
> >>>>>>>>>>>  		set_page_dirty(page);
> >>>>>>>>>>>  		set_cold_data(page);
> >>>>>>>>>>>  	} else {
> >>>>>>>>>>> @@ -864,7 +883,6 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
> >>>>>>>>>>>  			.io_type = FS_GC_DATA_IO,
> >>>>>>>>>>>  		};
> >>>>>>>>>>>  		bool is_dirty = PageDirty(page);
> >>>>>>>>>>> -		int err;
> >>>>>>>>>>>  
> >>>>>>>>>>>  retry:
> >>>>>>>>>>>  		set_page_dirty(page);
> >>>>>>>>>>> @@ -889,6 +907,7 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
> >>>>>>>>>>>  	}
> >>>>>>>>>>>  out:
> >>>>>>>>>>>  	f2fs_put_page(page, 1);
> >>>>>>>>>>> +	return err;
> >>>>>>>>>>>  }
> >>>>>>>>>>>  
> >>>>>>>>>>>  /*
> >>>>>>>>>>> @@ -898,7 +917,7 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
> >>>>>>>>>>>   * If the parent node is not valid or the data block address is different,
> >>>>>>>>>>>   * the victim data block is ignored.
> >>>>>>>>>>>   */
> >>>>>>>>>>> -static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> >>>>>>>>>>> +static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> >>>>>>>>>>>  		struct gc_inode_list *gc_list, unsigned int segno, int gc_type)
> >>>>>>>>>>>  {
> >>>>>>>>>>>  	struct super_block *sb = sbi->sb;
> >>>>>>>>>>> @@ -906,6 +925,7 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> >>>>>>>>>>>  	block_t start_addr;
> >>>>>>>>>>>  	int off;
> >>>>>>>>>>>  	int phase = 0;
> >>>>>>>>>>> +	int submitted = 0;
> >>>>>>>>>>>  
> >>>>>>>>>>>  	start_addr = START_BLOCK(sbi, segno);
> >>>>>>>>>>>  
> >>>>>>>>>>> @@ -922,7 +942,7 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> >>>>>>>>>>>  
> >>>>>>>>>>>  		/* stop BG_GC if there is not enough free sections. */
> >>>>>>>>>>>  		if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0))
> >>>>>>>>>>> -			return;
> >>>>>>>>>>> +			return submitted;
> >>>>>>>>>>>  
> >>>>>>>>>>>  		if (check_valid_map(sbi, segno, off) == 0)
> >>>>>>>>>>>  			continue;
> >>>>>>>>>>> @@ -994,6 +1014,7 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> >>>>>>>>>>>  		if (inode) {
> >>>>>>>>>>>  			struct f2fs_inode_info *fi = F2FS_I(inode);
> >>>>>>>>>>>  			bool locked = false;
> >>>>>>>>>>> +			int err;
> >>>>>>>>>>>  
> >>>>>>>>>>>  			if (S_ISREG(inode->i_mode)) {
> >>>>>>>>>>>  				if (!down_write_trylock(&fi->i_gc_rwsem[READ]))
> >>>>>>>>>>> @@ -1013,12 +1034,16 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> >>>>>>>>>>>  			start_bidx = f2fs_start_bidx_of_node(nofs, inode)
> >>>>>>>>>>>  								+ ofs_in_node;
> >>>>>>>>>>>  			if (f2fs_post_read_required(inode))
> >>>>>>>>>>> -				move_data_block(inode, start_bidx, gc_type,
> >>>>>>>>>>> -								segno, off);
> >>>>>>>>>>> +				err = move_data_block(inode, start_bidx,
> >>>>>>>>>>> +							gc_type, segno, off);
> >>>>>>>>>>>  			else
> >>>>>>>>>>> -				move_data_page(inode, start_bidx, gc_type,
> >>>>>>>>>>> +				err = move_data_page(inode, start_bidx, gc_type,
> >>>>>>>>>>>  								segno, off);
> >>>>>>>>>>>  
> >>>>>>>>>>> +			if (!err && (gc_type == FG_GC ||
> >>>>>>>>>>> +					f2fs_post_read_required(inode)))
> >>>>>>>>>>> +				submitted++;
> >>>>>>>>>>> +
> >>>>>>>>>>>  			if (locked) {
> >>>>>>>>>>>  				up_write(&fi->i_gc_rwsem[WRITE]);
> >>>>>>>>>>>  				up_write(&fi->i_gc_rwsem[READ]);
> >>>>>>>>>>> @@ -1030,6 +1055,8 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> >>>>>>>>>>>  
> >>>>>>>>>>>  	if (++phase < 5)
> >>>>>>>>>>>  		goto next_step;
> >>>>>>>>>>> +
> >>>>>>>>>>> +	return submitted;
> >>>>>>>>>>>  }
> >>>>>>>>>>>  
> >>>>>>>>>>>  static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
> >>>>>>>>>>> @@ -1057,6 +1084,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>  	int seg_freed = 0;
> >>>>>>>>>>>  	unsigned char type = IS_DATASEG(get_seg_entry(sbi, segno)->type) ?
> >>>>>>>>>>>  						SUM_TYPE_DATA : SUM_TYPE_NODE;
> >>>>>>>>>>> +	int submitted = 0;
> >>>>>>>>>>>  
> >>>>>>>>>>>  	/* readahead multi ssa blocks those have contiguous address */
> >>>>>>>>>>>  	if (sbi->segs_per_sec > 1)
> >>>>>>>>>>> @@ -1100,10 +1128,11 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>  		 *                                  - lock_page(sum_page)
> >>>>>>>>>>>  		 */
> >>>>>>>>>>>  		if (type == SUM_TYPE_NODE)
> >>>>>>>>>>> -			gc_node_segment(sbi, sum->entries, segno, gc_type);
> >>>>>>>>>>> -		else
> >>>>>>>>>>> -			gc_data_segment(sbi, sum->entries, gc_list, segno,
> >>>>>>>>>>> +			submitted += gc_node_segment(sbi, sum->entries, segno,
> >>>>>>>>>>>  								gc_type);
> >>>>>>>>>>> +		else
> >>>>>>>>>>> +			submitted += gc_data_segment(sbi, sum->entries, gc_list,
> >>>>>>>>>>> +							segno, gc_type);
> >>>>>>>>>>>  
> >>>>>>>>>>>  		stat_inc_seg_count(sbi, type, gc_type);
> >>>>>>>>>>>  
> >>>>>>>>>>> @@ -1114,7 +1143,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
> >>>>>>>>>>>  		f2fs_put_page(sum_page, 0);
> >>>>>>>>>>>  	}
> >>>>>>>>>>>  
> >>>>>>>>>>> -	if (gc_type == FG_GC)
> >>>>>>>>>>> +	if (submitted)
> >>>>>>>>>>>  		f2fs_submit_merged_write(sbi,
> >>>>>>>>>>>  				(type == SUM_TYPE_NODE) ? NODE : DATA);
> >>>>>>>>>>>  
> >>>>>>>>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> >>>>>>>>>>> index fa2381c0bc47..214dd6326b4b 100644
> >>>>>>>>>>> --- a/fs/f2fs/node.c
> >>>>>>>>>>> +++ b/fs/f2fs/node.c
> >>>>>>>>>>> @@ -1584,8 +1584,10 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
> >>>>>>>>>>>  	return AOP_WRITEPAGE_ACTIVATE;
> >>>>>>>>>>>  }
> >>>>>>>>>>>  
> >>>>>>>>>>> -void f2fs_move_node_page(struct page *node_page, int gc_type)
> >>>>>>>>>>> +int f2fs_move_node_page(struct page *node_page, int gc_type)
> >>>>>>>>>>>  {
> >>>>>>>>>>> +	int err = 0;
> >>>>>>>>>>> +
> >>>>>>>>>>>  	if (gc_type == FG_GC) {
> >>>>>>>>>>>  		struct writeback_control wbc = {
> >>>>>>>>>>>  			.sync_mode = WB_SYNC_ALL,
> >>>>>>>>>>> @@ -1597,12 +1599,16 @@ void f2fs_move_node_page(struct page *node_page, int gc_type)
> >>>>>>>>>>>  		f2fs_wait_on_page_writeback(node_page, NODE, true);
> >>>>>>>>>>>  
> >>>>>>>>>>>  		f2fs_bug_on(F2FS_P_SB(node_page), PageWriteback(node_page));
> >>>>>>>>>>> -		if (!clear_page_dirty_for_io(node_page))
> >>>>>>>>>>> +		if (!clear_page_dirty_for_io(node_page)) {
> >>>>>>>>>>> +			err = -EAGAIN;
> >>>>>>>>>>>  			goto out_page;
> >>>>>>>>>>> +		}
> >>>>>>>>>>>  
> >>>>>>>>>>>  		if (__write_node_page(node_page, false, NULL,
> >>>>>>>>>>> -					&wbc, false, FS_GC_NODE_IO, NULL))
> >>>>>>>>>>> +					&wbc, false, FS_GC_NODE_IO, NULL)) {
> >>>>>>>>>>> +			err = -EAGAIN;
> >>>>>>>>>>>  			unlock_page(node_page);
> >>>>>>>>>>> +		}
> >>>>>>>>>>>  		goto release_page;
> >>>>>>>>>>>  	} else {
> >>>>>>>>>>>  		/* set page dirty and write it */
> >>>>>>>>>>> @@ -1613,6 +1619,7 @@ void f2fs_move_node_page(struct page *node_page, int gc_type)
> >>>>>>>>>>>  	unlock_page(node_page);
> >>>>>>>>>>>  release_page:
> >>>>>>>>>>>  	f2fs_put_page(node_page, 0);
> >>>>>>>>>>> +	return err;
> >>>>>>>>>>>  }
> >>>>>>>>>>>  
> >>>>>>>>>>>  static int f2fs_write_node_page(struct page *page,
> >>>>>>>>>>> -- 
> >>>>>>>>>>> 2.18.0
> >>>>>>>>>>
> >>>>>>>>>> .
> >>>>>>>>>>
> >>>>>>>>
> >>>>>>>> .
> >>>>>>>>
> >>>>>>
> >>>>>> .
> >>>>>>
> >>>>>
> >>>
> >>> .
> >>>
> > 
> > .
> >