Messages in this thread | | | Subject | Re: [PATCH] f2fs: fix fdatasync | From | Chao Yu <> | Date | Thu, 17 Nov 2016 20:12:25 +0800 |
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On 2016/11/17 11:41, Jaegeuk Kim wrote: > On Thu, Nov 17, 2016 at 11:35:58AM +0800, Chao Yu wrote: >> On 2016/11/17 10:59, Jaegeuk Kim wrote: >>> On Thu, Nov 17, 2016 at 10:51:37AM +0800, Chao Yu wrote: >>>> Hi Jaegeuk, >>>> >>>> On 2016/11/17 3:13, Jaegeuk Kim wrote: >>>>> Hi Chao, >>>>> >>>>> On Wed, Nov 16, 2016 at 08:12:11PM +0800, Chao Yu wrote: >>>>>> For below two cases, we can't guarantee data consistence: >>>>>> >>>>>> a) >>>>>> 1. xfs_io "pwrite 0 4195328" "fsync" >>>>>> 2. xfs_io "pwrite 4195328 1024" "fdatasync" >>>>>> 3. godown >>>>>> 4. umount & mount >>>>>> --> isize we updated before fdatasync won't be recovered >>>>>> >>>>>> b) >>>>>> 1. xfs_io "pwrite -S 0xcc 0 4202496" "fsync" >>>>>> 2. xfs_io "fpunch 4194304 4096" "fdatasync" >>>>>> 3. godown >>>>>> 4. umount & mount >>>>>> --> dnode we punched before fdatasync won't be recovered >>>>>> >>>>>> The reason is that normally fdatasync won't be aware of modification >>>>>> of metadata in file, e.g. isize changing, dnode updating, so in ->fsync >>>>>> we will skip flushing node pages for above cases, result in making >>>>>> fdatasynced file being lost during recovery. >>>>>> >>>>>> Introduce FDATASYNC_INO global ino cache for tracking node changing, >>>>>> later fdatasync choose to flush nodes depend on ino cache state. >>>>> >>>>> We don't need to add this additionally, and would be better to consider other >>>>> major metadata as well. >>>>> >>>>> How about this? >>>> >>>> Seems it can't track file after evict? >>> >>> Do we need that? That means inode page was already up-to-date? >> >> I mean if node/data page of inode were writeback by kworker, after evict, if >> user open it again and call fdatasync, after sudden power-off, we will not >> recover it. > > That will be handled by need_inode_block_update() below?
Confirmed, let me send v2 and do more tests.
Thanks,
> > Thanks, > > . >
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