Re: [PATCH 19/20] elevate writer count for custom 'struct file'

[Dave Hansen <haveblue@us.ibm.com>]

On Tue, 2006-06-27 at 19:40 -0700, Andrew Morton wrote:
> On Tue, 27 Jun 2006 15:14:56 -0700
> Dave Hansen <haveblue@us.ibm.com> wrote:
> 
> > Some filesystems forego the vfs and may_open() and create their
> > own 'struct file's.  Any of these users which set the write flag
> > on the file will cause an extra mnt_drop_write() on __fput(),
> > thus dropping the reference count too low.
> > 
> > These users tend to have artifical in-kernel vfsmounts which
> > aren't really exposed to userspace and can't be remounted, but
> > this patch is included for completeness and so that the warnings
> > don't trip over these cases.
> 
> Does the fake_file in fs/block_dev.c need similar treatment?

In practice, I think it should be OK.  The reference drop in __fput() is
only when the 'struct file' is !special_file(), which I assume all of
those block_dev.c files will be.  

I'll examine it in more detail to make sure this is true for all of the
users.

-- Dave

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