From: Chao Yu <chao@kernel.org>
To: Hyeong-Jun Kim <hj514.kim@samsung.com>, Jaegeuk Kim <jaegeuk@kernel.org>
Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] F2FS: invalidate META_MAPPING before IPU/DIO write
Date: Tue, 2 Nov 2021 15:36:07 +0800 [thread overview]
Message-ID: <037676b3-4f66-c749-5c8b-ac0c1ef7facf@kernel.org> (raw)
In-Reply-To: <20211102071002.71823-1-hj514.kim@samsung.com>
On 2021/11/2 15:10, Hyeong-Jun Kim wrote:
> Encrypted pages during GC are read and cached in META_MAPPING.
> However, due to cached pages in META_MAPPING, there is an issue where
> newly written pages are lost by IPU or DIO writes.
>
> Thread A - f2fs_gc() Thread B
> /* phase 3 */
> down_write(i_gc_rwsem)
> ra_data_block() ---- (a)
> up_write(i_gc_rwsem)
> f2fs_direct_IO() :
> - down_read(i_gc_rwsem)
> - __blockdev_direct_io()
> - get_data_block_dio_write()
> - f2fs_dio_submit_bio() ---- (b)
> - up_read(i_gc_rwsem)
> /* phase 4 */
> down_write(i_gc_rwsem)
> move_data_block() ---- (c)
> up_write(i_gc_rwsem)
>
> (a) In phase 3 of f2fs_gc(), up-to-date page is read from storage and
> cached in META_MAPPING.
> (b) In thread B, writing new data by IPU or DIO write on same blkaddr as
> read in (a). cached page in META_MAPPING become out-dated.
> (c) In phase 4 of f2fs_gc(), out-dated page in META_MAPPING is copied to
> new blkaddr. In conclusion, the newly written data in (b) is lost.
>
> To address this issue, invalidating pages in META_MAPPING before IPU or
> DIO write.
>
> Fixes: 6aa58d8ad20a ("f2fs: readahead encrypted block during GC")
> Signed-off-by: Hyeong-Jun Kim <hj514.kim@samsung.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Thanks,
prev parent reply other threads:[~2021-11-02 7:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20211102071004epcas1p4d6422cb2ccaa6af495cee4f041f63048@epcas1p4.samsung.com>
2021-11-02 7:10 ` [PATCH v4] F2FS: invalidate META_MAPPING before IPU/DIO write Hyeong-Jun Kim
2021-11-02 7:36 ` Chao Yu [this message]
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