Jan Kara <j...@suse.cz> writes: >> I think you know how to solve it though. You can add the periodic flush >> in own task. And you can check bdi->dirty_exceeded in any handlers. > Sure, you can have your private thread. That is possible but you will > have to duplicate flusher logic and you will still get odd behavior e.g. > when your filesystem is on one partition and another filesystem is on a > different partition of the same disk.
Right. But it is what current FSes are doing more or less. >> Well, ok. The alternative plan but more bigger change is to add the >> handler to writeback task path. This would be better way, and core >> should be able to request to flush with usual way (I guess this is what >> you are concerning). And I believe some FS can implement the simpler >> and more efficient writeback path. >> >> But this would look like what reiserfs4 was submitted in past (before >> bdi was introduced), and unfortunately never accepted though. >> >> Since situation was changed, will we accept it? >> >> OK, why my FS requires it? Because basic strategy try to keep the >> consistency of user view, not only internal metadata consistency. >> I.e. it works like to flush the snapshot of user view. >> >> So, flushing metadata/data by arbitrary order like current writeback >> task does is unacceptable (of course, except request by user). And >> writeback task will never know the correct order of FS. > OK, thanks for explanation. Now I understand what you are trying to do. > Would it be enough if you could track dirty inodes inside your filesystem > and provide some callback for flusher so that you can queue these inodes in > the IO queue? Yes, I guess so. I'm not doing the experiment this plan yet, so I'm not sure though. If we provide the callback something like ->writeback_sb_inodes(), it would work. And the better design is to remove duplication of dirty inode tracking on writeback task and own FS though. (However, this is quite optional) Thanks. -- OGAWA Hirofumi <hirof...@mail.parknet.co.jp> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
