From: Wu Bo via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>
To: chao@kernel.org
Cc: jaegeuk@kernel.org, linux-kernel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: fix to avoid racing in between read and OPU dio write
Date: Wed, 15 May 2024 02:32:19 -0600 [thread overview]
Message-ID: <20240515083219.1601289-1-bo.wu@vivo.com> (raw)
In-Reply-To: <20240510023906.281700-1-chao@kernel.org>
On Fri, May 10, 2024 at 10:39:06AM +0800, Chao Yu wrote:
> If lfs mode is on, buffered read may race w/ OPU dio write as below,
> it may cause buffered read hits unwritten data unexpectly, and for
> dio read, the race condition exists as well.
>
> Thread A Thread B
> - f2fs_file_write_iter
> - f2fs_dio_write_iter
> - __iomap_dio_rw
> - f2fs_iomap_begin
> - f2fs_map_blocks
> - __allocate_data_block
> - allocated blkaddr #x
> - iomap_dio_submit_bio
> - f2fs_file_read_iter
> - filemap_read
> - f2fs_read_data_folio
> - f2fs_mpage_readpages
> - f2fs_map_blocks
> : get blkaddr #x
> - f2fs_submit_read_bio
> IRQ
> - f2fs_read_end_io
> : read IO on blkaddr #x complete
> IRQ
> - iomap_dio_bio_end_io
> : direct write IO on blkaddr #x complete
>
Looks like every COW filesystem would meet this situation. What's the solution
of other FS?
> This patch introduces a new per-inode i_opu_rwsem lock to avoid
> such race condition.
>
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next prev parent reply other threads:[~2024-05-15 8:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-10 2:39 [f2fs-dev] [PATCH v2] f2fs: fix to avoid racing in between read and OPU dio write Chao Yu
2024-05-14 16:09 ` Jaegeuk Kim
2024-05-15 1:42 ` Chao Yu
2024-05-15 4:42 ` Jaegeuk Kim
2024-05-15 6:38 ` Chao Yu
2024-05-15 8:32 ` Wu Bo via Linux-f2fs-devel [this message]
2024-05-15 8:40 ` Markus Elfring via Linux-f2fs-devel
2024-05-17 8:15 ` kernel test robot
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