Messages in this thread | | | Date | Tue, 2 Nov 2021 09:28:56 +0800 | Subject | Re: [PATCH v2] F2FS: invalidate META_MAPPING before IPU/DIO write | From | Chao Yu <> |
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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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