Re: [autofs] [RFC PATCH]autofs4: hang and proposed fix

[jtk@us.ibm.com (John T. Kohl)]

>>>>> "Christoph" == Christoph Hellwig <hch@infradead.org> writes:

Christoph> On Wed, Dec 07, 2005 at 12:46:39PM -0500, Will Taber wrote:
>> problem at hand.  Anyway, with this information, is it appropriate for 
>> us to replace our calls to lookup_one_len with calls to path_walk or is 
>> that also forbidden?

Christoph> path_walk and firends resolve a full path.  As such they are
Christoph> definitly not suitable for stackable filesystem, they are
Christoph> intendeded only for implementating syscalls (and syscall-like
Christoph> interfaces, e.g. some ioctls)

path_lookup() takes a pathname and interprets it relative to cwd or
root, so it's definitely not useful for stacking.  But path_walk() takes
a pathname fragment and an initialized nameidata (start point), so it
*could* be used to resolve a single component, or multiple components.

If lookup_one_len() is for use within the caller's file system only, and
path_walk() is not suitable for stacking, then what calls *are* suitable
for stacking file systems to use?  We want to start with an existing
(dentry,vfsmnt) and a pathname component, converting it to the
(dentry,vfsmnt) of the result.

-- 
John Kohl
Senior Software Engineer - Rational Software - IBM Software Group
Lexington, Massachusetts, USA
jtk@us.ibm.com
<http://www.ibm.com/software/rational/>