Re: [f2fs-dev] [PATCH] f2fs: remove race condition in releasing cblocks

From: Jaegeuk Kim <jaegeuk@kernel.org>
To: Daeho Jeong <daeho43@gmail.com>
Cc: kernel@vger.kernel.org, kernel-team@android.com,
	Daeho Jeong <daehojeong@google.com>,
	linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: remove race condition in releasing cblocks
Date: Fri, 8 May 2020 06:58:30 -0700	[thread overview]
Message-ID: <20200508135830.GC88927@google.com> (raw)
In-Reply-To: <20200508134831.GB88927@google.com>

On 05/08, Jaegeuk Kim wrote:
> Is this v2?

nvm. it seems the same version.

> 
> On 05/08, Daeho Jeong wrote:
> > From: Daeho Jeong <daehojeong@google.com>
> > 
> > Now, if writing pages and releasing compress blocks occur
> > simultaneously, and releasing cblocks is executed more than one time
> > to a file, then total block count of filesystem and block count of the
> > file could be incorrect and damaged.
> > 
> > We have to execute releasing compress blocks only one time for a file
> > without being interfered by writepages path.
> > 
> > Signed-off-by: Daeho Jeong <daehojeong@google.com>
> > Reviewed-by: Chao Yu <yuchao0@huawei.com>
> > ---
> >  fs/f2fs/file.c | 34 ++++++++++++++++++++++++----------
> >  1 file changed, 24 insertions(+), 10 deletions(-)
> > 
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 4aab4b42d8ba..f7de2a1da528 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -3488,6 +3488,7 @@ static int f2fs_release_compress_blocks(struct file *filp, unsigned long arg)
> >  	pgoff_t page_idx = 0, last_idx;
> >  	unsigned int released_blocks = 0;
> >  	int ret;
> > +	int writecount;
> >  
> >  	if (!f2fs_sb_has_compression(F2FS_I_SB(inode)))
> >  		return -EOPNOTSUPP;
> > @@ -3502,20 +3503,33 @@ static int f2fs_release_compress_blocks(struct file *filp, unsigned long arg)
> >  	if (ret)
> >  		return ret;
> >  
> > -	if (!F2FS_I(inode)->i_compr_blocks)
> > -		goto out;
> > -
> >  	f2fs_balance_fs(F2FS_I_SB(inode), true);
> >  
> >  	inode_lock(inode);
> >  
> > -	if (!IS_IMMUTABLE(inode)) {
> > -		F2FS_I(inode)->i_flags |= F2FS_IMMUTABLE_FL;
> > -		f2fs_set_inode_flags(inode);
> > -		inode->i_ctime = current_time(inode);
> > -		f2fs_mark_inode_dirty_sync(inode, true);
> > +	writecount = atomic_read(&inode->i_writecount);
> > +	if ((filp->f_mode & FMODE_WRITE && writecount != 1) || writecount) {
> > +		ret = -EBUSY;
> > +		goto out;
> >  	}
> >  
> > +	if (IS_IMMUTABLE(inode)) {
> > +		ret = -EINVAL;
> > +		goto out;
> > +	}
> > +
> > +	ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
> > +	if (ret)
> > +		goto out;
> > +
> > +	if (!F2FS_I(inode)->i_compr_blocks)
> > +		goto out;
> > +
> > +	F2FS_I(inode)->i_flags |= F2FS_IMMUTABLE_FL;
> > +	f2fs_set_inode_flags(inode);
> > +	inode->i_ctime = current_time(inode);
> > +	f2fs_mark_inode_dirty_sync(inode, true);
> > +
> >  	down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> >  	down_write(&F2FS_I(inode)->i_mmap_sem);
> >  
> > @@ -3554,9 +3568,9 @@ static int f2fs_release_compress_blocks(struct file *filp, unsigned long arg)
> >  
> >  	up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> >  	up_write(&F2FS_I(inode)->i_mmap_sem);
> > -
> > -	inode_unlock(inode);
> >  out:
> > +	inode_unlock(inode);
> > +
> >  	mnt_drop_write_file(filp);
> >  
> >  	if (ret >= 0) {
> > -- 
> > 2.26.2.645.ge9eca65c58-goog
> 
> 
> _______________________________________________
> Linux-f2fs-devel mailing list
> Linux-f2fs-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel