From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by mail19.linbit.com (LINBIT Mail Daemon) with ESMTP id AD27242A583 for ; Fri, 28 Jan 2022 02:34:35 +0100 (CET) Date: Thu, 27 Jan 2022 17:34:31 -0800 From: Jaegeuk Kim To: NeilBrown Message-ID: References: <164325106958.29787.4865219843242892726.stgit@noble.brown> <164325158956.29787.7016948342209980097.stgit@noble.brown> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <164325158956.29787.7016948342209980097.stgit@noble.brown> Cc: "Darrick J. Wong" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, drbd-dev@lists.linbit.com, Paolo Valente , Miklos Szeredi , Trond Myklebust , Ilya Dryomov , linux-ext4@vger.kernel.org, Chao Yu , linux-block@vger.kernel.org, linux-nilfs@vger.kernel.org, ceph-devel@vger.kernel.org, Ryusuke Konishi , Jens Axboe , linux-nfs@vger.kernel.org, Andrew Morton , Jeff Layton , Philipp Reisner , linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, Lars Ellenberg , Anna Schumaker Subject: Re: [Drbd-dev] [PATCH 3/9] f2fs: change retry waiting for f2fs_write_single_data_page() List-Id: "*Coordination* of development, patches, contributions -- *Questions* \(even to developers\) go to drbd-user, please." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 01/27, NeilBrown wrote: > f2fs_write_single_data_page() can return -EAGAIN if it cannot get > the cp_rwsem lock - it holds a page lock and so cannot wait for it. > > Some code which calls f2fs_write_single_data_page() use > congestion_wait() and then tries again. congestion_wait() doesn't do > anything useful as congestion is no longer tracked. So this is just a > simple sleep. > > A better approach is it wait until the cp_rwsem lock can be taken - then > try again. There is certainly no point trying again *before* the lock > can be taken. > > Signed-off-by: NeilBrown > --- > fs/f2fs/compress.c | 6 +++--- > fs/f2fs/data.c | 9 ++++++--- > 2 files changed, 9 insertions(+), 6 deletions(-) > > diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c > index d0c3aeba5945..58ff7f4b296c 100644 > --- a/fs/f2fs/compress.c > +++ b/fs/f2fs/compress.c > @@ -1505,9 +1505,9 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc, > if (IS_NOQUOTA(cc->inode)) > return 0; > ret = 0; > - cond_resched(); > - congestion_wait(BLK_RW_ASYNC, > - DEFAULT_IO_TIMEOUT); > + /* Wait until we can get the lock, then try again. */ > + f2fs_lock_op(F2FS_I_SB(cc->inode)); > + f2fs_unlock_op(F2FS_I_SB(cc->inode)); Since checkpoint uses down_write(cp_rwsem), I'm not sure the write path is safe and needs to wait for checkpoint. Can we just do io_schedule_timeout()? > goto retry_write; > } > return ret; > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > index 8c417864c66a..1d2341163e2c 100644 > --- a/fs/f2fs/data.c > +++ b/fs/f2fs/data.c > @@ -3047,9 +3047,12 @@ static int f2fs_write_cache_pages(struct address_space *mapping, > } else if (ret == -EAGAIN) { > ret = 0; > if (wbc->sync_mode == WB_SYNC_ALL) { > - cond_resched(); > - congestion_wait(BLK_RW_ASYNC, > - DEFAULT_IO_TIMEOUT); > + /* Wait until we can get the > + * lock, then try again. > + */ > + f2fs_lock_op(F2FS_I_SB(mapping->host)); > + f2fs_unlock_op(F2FS_I_SB(mapping->host)); > + > goto retry_write; > } > goto next; >