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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Qjdofq8Y; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Qjdofq8Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3A20C51EE5; Wed, 28 Aug 2024 15:27:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724858860; bh=golWfvhGGRNH0zGtd5RPOTm6f8BFtB3I2tmehBi4BmY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Qjdofq8Yf4iRQblN+EzaiIT/YPNbh1xmY0tCxIg4kqxa2MJG5kz+UKiiVnPavj/1H mhU4CWau6HfG2A8QCugQROGyCIrmGGAd+aCoQ8c24szWh82J1JJEqFphfmPCtJLJin oySdiiN0olNiKTWmDFkx0h9k9LSd/FR8FHD66D7LvbPk7lvf+bvzffqLkaQcYXRFv6 /i0wAKfnJGlzHKul19ORm5adrSHSAwAqkJwZrVrxyLWnxfsC88ocz7yBb7edU0eUJz WO5RfEnSemdQbmTxhJEg6nsH4aMUyJ5WG8E4KvKzWag8Ze9/4fpW+GPFy1rF/Uifzk Ff2Nvm55fomsw== Date: Wed, 28 Aug 2024 15:27:39 +0000 From: Jaegeuk Kim To: Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/4] f2fs: atomic: fix to not allow GC to pollute atomic_file Message-ID: References: <20240814134815.801303-1-chao@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240814134815.801303-1-chao@kernel.org> On 08/14, Chao Yu wrote: > SQLite App GC Thread Shrinker > - f2fs_ioc_start_atomic_write > > - f2fs_ioc_commit_atomic_write > - f2fs_commit_atomic_write > - filemap_write_and_wait_range > : write atomic_file's data to cow_inode > echo 3 > drop_caches > - f2fs_gc > - gc_data_segment > - move_data_page > - set_page_dirty > : it may load data of previous > transaction into pagecache. > - f2fs_down_write(&fi->i_gc_rwsem[WRITE]) > - __f2fs_commit_atomic_write > - f2fs_up_write(&fi->i_gc_rwsem[WRITE]) > > During committing atomic_file, GC may be triggered to migrate > atomic_file's block, so it may contain data of previous transaction > in page cache, we should drop atomic_file's cache once it was > migrated by GC. > > And also, we should writeback atomic_file and cow_file's data > w/ i_gc_rwsem lock held, in order to avoid block address change > during __f2fs_commit_atomic_write(). > > Meahwhile, this patch adds f2fs_wait_on_block_writeback_range() > to wait completion of block migration. > > Fixes: 3db1de0e582c ("f2fs: change the current atomic write way") > Signed-off-by: Chao Yu > --- > v2: > - fix error path handling. > fs/f2fs/segment.c | 27 +++++++++++++++++++++++---- > 1 file changed, 23 insertions(+), 4 deletions(-) > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index 3aee71c9f3c6..a43054ab0cf1 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -236,6 +236,9 @@ static int __replace_atomic_write_block(struct inode *inode, pgoff_t index, > return err; > } > > + if (__is_valid_data_blkaddr(dn.data_blkaddr)) > + f2fs_wait_on_block_writeback_range(inode, dn.data_blkaddr, 1); > + > if (recover) { > /* dn.data_blkaddr is always valid */ > if (!__is_valid_data_blkaddr(new_addr)) { > @@ -339,6 +342,9 @@ static int __f2fs_commit_atomic_write(struct inode *inode) > goto out; > } > > + f2fs_wait_on_block_writeback_range(cow_inode, > + blkaddr, 1); > + > new = f2fs_kmem_cache_alloc(revoke_entry_slab, GFP_NOFS, > true, NULL); > > @@ -379,16 +385,29 @@ int f2fs_commit_atomic_write(struct inode *inode) > struct f2fs_inode_info *fi = F2FS_I(inode); > int err; > > + f2fs_down_write(&fi->i_gc_rwsem[WRITE]); > + > err = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX); > if (err) > - return err; > + goto out; > > - f2fs_down_write(&fi->i_gc_rwsem[WRITE]); > - f2fs_lock_op(sbi); > + /* writeback GCing page of cow_inode */ > + err = filemap_write_and_wait_range(fi->cow_inode->i_mapping, > + 0, LLONG_MAX); > + if (err) > + goto out; > > - err = __f2fs_commit_atomic_write(inode); > + filemap_invalidate_lock(inode->i_mapping); > + > + /* don't allow clean page loaded by GC to pollute atomic_file */ > + truncate_pagecache(inode, 0); Performance impact? > > + f2fs_lock_op(sbi); > + err = __f2fs_commit_atomic_write(inode); > f2fs_unlock_op(sbi); > + > + filemap_invalidate_unlock(inode->i_mapping); > +out: > f2fs_up_write(&fi->i_gc_rwsem[WRITE]); > > return err; > -- > 2.40.1