Oh, here no-journalled-data is misleading, I mean mount in data=writeback mode or data=ordered mode, not in data=journal mode. 2011/4/27 Andreas Dilger <adilger@xxxxxxxxx>: > On 2011-04-26, at 4:47 AM, Niraj Kulkarni wrote: >> If I am thinking correctly, journal would be checkpointed on >> filesystem unmount calls. >> This implies the given scenario would be pretty rare. >> >> ie first filesystem should be mounted in full-journal mode, and >> crashed prior to checkpoint. >> then it should be remounted in no-journalled-data mode without >> recovery and again remounted in full journalled mode with recovery. > > It shouldn't be possible to mount the filesystem in no-journal mode > without doing journal recovery. The filesystem sets an INCOMPAT_RECOVER > flag when the journal has any transactions in it, and the journal should > be replayed before the filesystem is finished mounting. > > Looking at ext4_fill_super() the "noload" mount option is used to avoid > loading the journal even if there is a journal (COMPAT_HAS_JOURNAL is set), > but if INCOMPAT_RECOVER is set the filesystem will refuse to mount. > > >> On Tuesday 26 April 2011 02:53 PM, Ding Dinghua wrote: >>> I think it's not only a performance issue but more important, a >>> correctness issue. >>> Revoke table is used for preventing the wrong replay of journal which >>> cause data corruption: >>> If block A has been journalled its modification, committed to journal >>> and hasn't been checkpointed, >>> and in later transactions block A is freed and reused for data in >>> no-journalled-data mode, then If >>> we don't have revoke table which recording the releasing event, replay >>> of journal will overwrite the new data, >>> which causing data corruption. >>> >>> 2011/4/26 Yongqiang Yang<xiaoqiangnk@xxxxxxxxx>: >>>> AFAIK, it can accelerate the recovering process. If a block is in the >>>> revoke table of a transaction t1 and t1 is committed, then the there >>>> is no need to recover the block in transactions which is earlier than >>>> t1. >>>> >>>> On Tue, Apr 26, 2011 at 4:29 PM, Niraj Kulkarni >>>> <kulkarniniraj14@xxxxxxxxx> wrote: >>>>> Hi all, >>>>> I am new to fs development. I am trying to modify the journal structure >>>>> of JBD. While analyzing the code, I could understand most of the things, but >>>>> I am not able to understand the need of revoke mechanism. Can anybody >>>>> enlighten me on this issue? >>>>> >>>>> Regards >>>>> Niraj >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in >>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>> >>>> >>>> >>>> -- >>>> Best Wishes >>>> Yongqiang Yang >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> >>> >>> >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > Cheers, Andreas > > > > > > -- Ding Dinghua -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
