Re: [PATCH v2 1/5] fat: allocate persistent inode numbers

From: J. Bruce Fields
Date: Thu Sep 13 2012 - 10:46:02 EST


On Thu, Sep 13, 2012 at 11:24:30PM +0900, Namjae Jeon wrote:
> 2012/9/13, OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>:
> > "J. Bruce Fields" <bfields@xxxxxxxxxxxx> writes:
> >
> >>> >> Grepping around... Documentation/sysctl/vm.txt mentions a
> >>> >> vfs_cache_pressure parameter.
> >>> >> Yeah. And dirty hack will be possible to adjust sb->s_shrink.batch.
> >>> > I am worrying if it could lead to OOM condition on embedded
> >>> > system(short memory(DRAM) and support 3TB HDD disk of big size.)
> >>> >
> >>> > Please let me know if any issues or queries.
> >>>
> >>> So, now I think stable inode number may be useful if there are users of
> >>> it. And I guess those functionality is no collisions with -mm. And I
> >>> suppose we can add two modes for "nfs" option (e.g. nfs=1 and nfs=2).
> >>>
> >>> If nfs=1, works like current -mm without no limited operations.
> >>
> >> Apologies, I haven't been following the conversation carefully: remind
> >> me what "works like current -mm" means?
> >
> > Current -mm means the best-effort work only if inode cache is not
> > evicted. I.e. if there is no inode cache anymore on server, server
> > would return ESTALE. So I guess the behavior would not be stable
> > relatively.
> Hi OGAWA.
> Sorry for late response.
> Okay, I will resend patchset include your suggeston.(-o nfs=2)
> Do you mind adding busy list patch to avoid unlink issue ?
> And in case of rename, FAT retrun EBUSY while opening file.
> We can limit only rename.

The server doesn't necessarily know whether a client has the file open,
so does that really help?

--b.

> Let me know your opinion.
>
> Thanks OGAWA!
>
> >
> > Thanks.
> >
> >>> If nfs=2, try to make stable FH and limit some operations
> >>>
> >>> (option name doesn't matter here.)
> >>>
> >>> Does this work fine?
> > --
> > OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
> >
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