linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: fix quota_sync failure due to f2fs_lock

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Date:   Thu, 23 Apr 2020 12:49:52 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, kernel-team@...roid.com
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: fix quota_sync failure due to
 f2fs_lock_op

On 04/23, Chao Yu wrote:
> On 2020/4/17 5:39, Jaegeuk Kim wrote:
> > f2fs_quota_sync() uses f2fs_lock_op() before flushing dirty pages, but
> > f2fs_write_data_page() returns EAGAIN.
> > Likewise dentry blocks, we can just bypass getting the lock, since quota
> > blocks are also maintained by checkpoint.
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> > ---
> > v2:
> >  - fix multipage write case
> > 
> >  fs/f2fs/compress.c | 2 +-
> >  fs/f2fs/data.c     | 4 ++--
> >  2 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> > index df7b2d15eacde..faaa358289010 100644
> > --- a/fs/f2fs/compress.c
> > +++ b/fs/f2fs/compress.c
> > @@ -985,7 +985,7 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
> >  	loff_t psize;
> >  	int i, err;
> >  
> > -	if (!f2fs_trylock_op(sbi))
> > +	if (!IS_NOQUOTA(inode) && !f2fs_trylock_op(sbi))
> >  		return -EAGAIN;
> 
> I encounter deadlock..
> 
> Should call f2fs_unlock_op() for non-quota compressed inode later.

Could you elaborate a bit?

> 
> Thanks,
> 
> >  
> >  	set_new_dnode(&dn, cc->inode, NULL, NULL, 0);
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index accd28728642a..5c8d3823d7593 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -2656,8 +2656,8 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
> >  			f2fs_available_free_memory(sbi, BASE_CHECK))))
> >  		goto redirty_out;
> >  
> > -	/* Dentry blocks are controlled by checkpoint */
> > -	if (S_ISDIR(inode->i_mode)) {
> > +	/* Dentry/quota blocks are controlled by checkpoint */
> > +	if (S_ISDIR(inode->i_mode) || IS_NOQUOTA(inode)) {
> >  		fio.need_lock = LOCK_DONE;
> >  		err = f2fs_do_write_data_page(&fio);
> >  		goto done;
> >