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SubjectRe: [PATCH v2] F2FS: invalidate META_MAPPING before IPU/DIO write
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On 2021/11/1 16:46, 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,

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