Re: [PATCH 5/5] f2fs: Fix for parent inode information during server cache eviction

[Jaegeuk Kim <jaegeuk.kim@samsung.com>]

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2012-12-10 (월), 12:40 +0900, Namjae Jeon:
> 2012/12/10, Jaegeuk Kim <jaegeuk.kim@samsung.com>:
> > 2012-12-08 (토), 14:55 +0900, Namjae Jeon:
> >> From: Namjae Jeon <namjae.jeon@samsung.com>
> >>
> >> Test Case:
> >> [NFS Client]
> >> ls -lR .
> >>
> >> [NFS Server]
> >> while [ 1 ]
> >> do
> >> echo 3 > /proc/sys/vm/drop_caches
> >> done
> >>
> >> Error: "No such file or directory"
> >>
> >> When cache is dropped at the server, it results in lookup failure at the
> >> NFS client. Even though the file exists. Looking at the code to rebuild
> >> the inode in case of cache eviction. It tries to initiate a lookup
> >> operation
> >> for ".." to get the parent information using the on-disk inode number.
> >>
> >
> > Could you describe why this patch resolves that bug?
> > Before applying this, we need to figure out why that bug is occurred.
> > IMO, from the viewpoint of functionality, ".." resolution should work
> > too.
> dotdot entry of f2fs is stored when creating only directory not
> regular file. Am I correct ?

Yep.

> So when the parent of file was evicted, I thought we could not get
> parent inode number of file thoughout dotdot entry.

What do you mean the parent of file? Isn't it a directory?

> And f2fs inode is having parent inode number unlike other fs. so I
> think we can use this special thing by storing f2fs_inode_info.

f2fs stores a dotdot dentry *likewise* other fs.
The pino in f2fs_inode is specially added for POR intentionally.

Still I cannot imagine the bug scenario.

> 
> Thanks.
> > Thanks,
> >
> > --
> > Jaegeuk Kim
> > Samsung
> >
> --
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-- 
Jaegeuk Kim
Samsung

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