Messages in this thread | | | Subject | Re: [PATCH] f2fs: fix to avoid data corruption by forbidding SSR overwrite | From | Chao Yu <> | Date | Mon, 19 Aug 2019 14:30:12 +0800 |
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On 2019/8/16 11:03, Chao Yu wrote: > There is one case can cause data corruption. > > - write 4k to fileA > - fsync fileA, 4k data is writebacked to lbaA > - write 4k to fileA > - kworker flushs 4k to lbaB; dnode contain lbaB didn't be persisted yet > - write 4k to fileB > - kworker flush 4k to lbaA due to SSR > - SPOR -> dnode with lbaA will be recovered, however lbaA contains fileB's > data > > One solution is tracking all fsynced file's block history, and disallow > SSR overwrite on newly invalidated block on that file. > > However, during recovery, no matter the dnode is flushed or fsynced, all > previous dnodes until last fsynced one in node chain can be recovered, > that means we need to record all block change in flushed dnode, which > will cause heavy cost, so let's just use simple fix by forbidding SSR > overwrite directly. >
Jaegeuk,
Please help to add below missed tag to keep this patch being merged in stable kernel.
Fixes: 5b6c6be2d878 ("f2fs: use SSR for warm node as well")
Thanks,
> Signed-off-by: Chao Yu <yuchao0@huawei.com> > --- > fs/f2fs/segment.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index 9d9d9a050d59..69b3b553ee6b 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -2205,9 +2205,11 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del) > if (!f2fs_test_and_set_bit(offset, se->discard_map)) > sbi->discard_blks--; > > - /* don't overwrite by SSR to keep node chain */ > - if (IS_NODESEG(se->type) && > - !is_sbi_flag_set(sbi, SBI_CP_DISABLED)) { > + /* > + * SSR should never reuse block which is checkpointed > + * or newly invalidated. > + */ > + if (!is_sbi_flag_set(sbi, SBI_CP_DISABLED)) { > if (!f2fs_test_and_set_bit(offset, se->ckpt_valid_map)) > se->ckpt_valid_blocks++; > } >
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