On Wed, Aug 03, 2022 at 12:53:39PM +0200, Lukas Czerner wrote: > Currently the I_DIRTY_TIME will never get set if the inode already has > I_DIRTY_INODE with assumption that it supersedes I_DIRTY_TIME. That's > true, however ext4 will only update the on-disk inode in > ->dirty_inode(), not on actual writeback. As a result if the inode > already has I_DIRTY_INODE state by the time we get to > __mark_inode_dirty() only with I_DIRTY_TIME, the time was already filled > into on-disk inode and will not get updated until the next I_DIRTY_INODE > update, which might never come if we crash or get a power failure. > > The problem can be reproduced on ext4 by running xfstest generic/622 > with -o iversion mount option. > > Fix it by allowing I_DIRTY_TIME to be set even if the inode already has > I_DIRTY_INODE. Also make sure that the case is properly handled in > writeback_single_inode() as well. Additionally changes in > xfs_fs_dirty_inode() was made to accommodate for I_DIRTY_TIME in flag. > > Thanks Jan Kara for suggestions on how to make this work properly. > > Cc: Dave Chinner <david@xxxxxxxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> > Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx> > Suggested-by: Jan Kara <jack@xxxxxxx> > --- > v2: Reworked according to suggestions from Jan .... > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c > index aa977c7ea370..cff05a4771b5 100644 > --- a/fs/xfs/xfs_super.c > +++ b/fs/xfs/xfs_super.c > @@ -658,7 +658,8 @@ xfs_fs_dirty_inode( > > if (!(inode->i_sb->s_flags & SB_LAZYTIME)) > return; > - if (flag != I_DIRTY_SYNC || !(inode->i_state & I_DIRTY_TIME)) > + if ((flag & ~I_DIRTY_TIME) != I_DIRTY_SYNC || > + !((inode->i_state | flag) & I_DIRTY_TIME)) > return; My eyes, they bleed. The dirty time code was already a horrid abomination, and this makes it worse. >From looking at the code, I cannot work out what the new semantics for I_DIRTY_TIME and I_DIRTY_SYNC are supposed to be, nor can I work out what the condition this is new code is supposed to be doing. I *can't verify it is correct* by reading the code. Can you please add a comment here explaining the conditions where we don't have to log a new timestamp update? Also, if "flag" now contains multiple flags, can you rename it "flags"? Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
