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Date:   Tue, 25 Sep 2018 18:42:21 -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: <20180926014221.GD3829@jaegeuk-macbookpro.roam.corp.google.com>
References: <20180912234053.8761-1-chao@kernel.org>
 <20180918010442.GA79604@jaegeuk-macbookpro.roam.corp.google.com>
 <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>
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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?

> 
> 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
> >>>>>>>>
> >>>>>>>> .
> >>>>>>>>
> >>>>>>
> >>>>>> .
> >>>>>>
> >>>>
> >>>> .
> >>>>
> >>>
> > 
> > .
> >