From: Chao Yu <chao@kernel.org>
To: Sayali Lokhande <sayalil@codeaurora.org>,
jaegeuk@kernel.org, yuchao0@huawei.com,
linux-f2fs-devel@lists.sourceforge.net
Cc: linux-kernel@vger.kernel.org
Subject: Re: [f2fs-dev] [PATCH] f2fs: Avoid double lock for cp_rwsem
Date: Thu, 23 Apr 2020 21:13:43 +0800 [thread overview]
Message-ID: <4b1a9995-5c4c-c547-e42a-bc6047dfb7f6@kernel.org> (raw)
In-Reply-To: <1587636832-17939-1-git-send-email-sayalil@codeaurora.org>
Hi Sayali,
On 2020-4-23 18:13, Sayali Lokhande wrote:
> Call stack :
> f2fs_write_checkpoint()
> -> block_operations(sbi)
> f2fs_lock_all(sbi);
> down_write(&sbi->cp_rwsem); => write lock held
> <>
It looks the full race condition should be?
Thread B
- open()
- igrab()
- write() write inline data
- unlink()
> -> f2fs_sync_node_pages()
> if (is_inline_node(page))
> flush_inline_data()
ilookup()
> page = f2fs_pagecache_get_page()
> if (!page)
> goto iput_out;
> iput_out:
- close()
- iput()
> iput(inode);
> -> f2fs_evict_inode()
> f2fs_truncate_blocks()
> f2fs_lock_op()
> down_read(&sbi->cp_rwsem); => read lock fail
>
> Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>
> ---
> fs/f2fs/checkpoint.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 5ba649e..5c504cf 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -1219,21 +1219,19 @@ static int block_operations(struct f2fs_sb_info *sbi)
> goto retry_flush_quotas;
> }
>
> -retry_flush_nodes:
> down_write(&sbi->node_write);
>
> if (get_pages(sbi, F2FS_DIRTY_NODES)) {
> up_write(&sbi->node_write);
Call up_write(&sbi->node_change) here could wake up threads earlier who hang on
this lock, how do you think?
Thanks,
> + f2fs_unlock_all(sbi);
> atomic_inc(&sbi->wb_sync_req[NODE]);
> err = f2fs_sync_node_pages(sbi, &wbc, false, FS_CP_NODE_IO);
> atomic_dec(&sbi->wb_sync_req[NODE]);
> - if (err) {
> - up_write(&sbi->node_change);
> - f2fs_unlock_all(sbi);
> + up_write(&sbi->node_change);
> + if (err)
> goto out;
> - }
> cond_resched();
> - goto retry_flush_nodes;
> + goto retry_flush_quotas;
> }
>
> /*
>
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next prev parent reply other threads:[~2020-04-23 13:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-23 10:13 [f2fs-dev] [PATCH] f2fs: Avoid double lock for cp_rwsem Sayali Lokhande
2020-04-23 13:13 ` Chao Yu [this message]
2020-04-23 20:19 ` Jaegeuk Kim
2020-04-24 0:16 ` Jaegeuk Kim
-- strict thread matches above, loose matches on Subject: below --
2020-04-23 13:07 Markus Elfring
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