Message-ID: <20181002024821.GA77803@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Mon, 1 Oct 2018 19:48:21 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Sahitya Tummala <stummala@...eaurora.org>
Cc:     Chao Yu <yuchao0@...wei.com>, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v3] f2fs: submit cached bio to avoid endless
 PageWriteback

On 10/01, Sahitya Tummala wrote:
> On Wed, Sep 26, 2018 at 12:20:38PM +0800, Chao Yu wrote:
> 
> Hi Chao, Jaegeuk,
> 
> Is there any further any conclusion on this thread?
> 
> I think we still need this patch in addition to another patch from Chao -
> "Revert: "f2fs: check last page index in cached bio to decide submission""
> to make sure it covers the encrypted data block path as well.

Queued and started to test. :P

> 
> Thanks,
> Sahitya.
> 
> > On 2018/9/26 11:32, Jaegeuk Kim wrote:
> > > 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@...wei.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@...wei.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.
> > 
> > Oh, I suspect that we will submit bio unnecessarily, or do I misunderstand
> > your idea?
> > 
> > IMO, how about just checking whether there is page in all [HOT|WARM|COLD]
> > bio caches belong to inode which caller want to flush/fsync, if there is,
> > then submit that bio.
> > 
> > That would be more simple to implement.
> > 
> > > 
> > >>
> > >> 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
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> .
> > >>>>>>>>>>>>
> > >>>>>>>>>>
> > >>>>>>>>>> .
> > >>>>>>>>>>
> > >>>>>>>>
> > >>>>>>>> .
> > >>>>>>>>
> > >>>>>>>
> > >>>>>
> > >>>>> .
> > >>>>>
> > >>>
> > >>> .
> > >>>
> > > 
> > > .
> > > 
> > 
> > 
> > 
> > _______________________________________________
> > Linux-f2fs-devel mailing list
> > Linux-f2fs-devel@...ts.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> 
> -- 
> --
> Sent by a consultant of the Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

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