From: Ming Zhang <blackmagic02881@gmail.com>
Subject: Re: (un)lock_kernel() ?
Date: Tue, 10 Apr 2007 12:55:05 -0400
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Cc: "John Anthony Kazos Jr." <jakj@j-a-k-j.com>,
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To: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
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On Tue, 2007-04-10 at 11:10 -0500, Dave Kleikamp wrote:
> On Tue, 2007-04-10 at 12:03 -0400, Ming Zhang wrote:
> > On Wed, 2007-04-04 at 12:52 -0400, John Anthony Kazos Jr. wrote:
> > > > According to Documentation/filesystems/Locking, ->get_sb() is called
> > > > with the BKL held, but looking through the code, I'm not able to find
> > > > where it is being taken.
> > > 
> > > I noticed that too. Unless I'm just dumb and can't see it, I'm not able to 
> > > find any BKL references during filesystem mounting until you get into 
> > > FS-specific code. I looked through everything from sys_mount through to 
> > > vfs_kern_mount. Documentation/filesystems/porting talks about several 
> > > situations where the VFS code was modified to not take the BKL, and BLK 
> > > calls were added by FS non-maintainers for safety until each FS could be 
> > > audited independently, but that wouldn't be the case, would it?
> > 
> > 
> > sys_mount->do_mount->do_new_mount->do_kern_mount path
> > 
> > part of sys_mount()
> > 
> > 1570                 goto out3;
> > 1571 
> > 1572         lock_kernel();
> > 1573         retval = do_mount((char *)dev_page, dir_page, (char *)type_page,
> > 1574                           flags, (void *)data_page);
> > 1575         unlock_kernel();
> > 1576         free_page(data_page);
> > 1577 
> > 1578 out3:
> > 1579         free_page(dev_page)
> 
> Thanks.  I missed that somehow.  It seems the documentation is correct.

welcome. i last time spend 30 minutes on finding it, so i pinned this
piece of info in my brain memory...