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Odd problem with Linux extfs (Fedora)

From: Thomas R. Bruce <trb2(at)not-real.cornell.edu>
Date: Mon Jun 20 2005 - 15:38:46 GMT
Bill and all:

This is one of those Twilight-Zone problems.

We use a set of directory layout conventions for numerous different 
projects that involves using a symbolic link from a set of off-web, 
project-related directories to connect with the appropriate 
sub-web-tree.  What's relevant is that this always results in swish-e 
being run against a filesystem tree whose root is a symbolic link, eg.

swish-e -i /usr/local/projects/anncon/httpd

which without the symlink would be

swish-e -i /var/www/html/anncon/

because  /usr/local/projects/anncon/httpd -> /var/www/html/anncon

Ordinarily, this works fine, and has for years.  Now I've created a new, 
linked structure of this kind, and it doesn't work at all.  Indexing via 
the "real" path (/var/www/html/anncon) works fine; indexing via the 
symlink doesn't-- it acts as though there are no files in the target 
directory (or that it can't access them).   The only difference seems to 
be that (for reasons we're still investigating) the I 
extended-filesystem attribute is set on this symlink but not on any of 
the other similar symlinks associated with other projects (these similar 
setups all work fine, just as they always have).  Stracing swish-e is 
unhelpful; a call to lstat on the symlink seems to succeed fine.

The chattr man page happily states that:

The 'I' attribute is used by the htree code to indicate that a directory 
is behind indexed using hashed trees. It may not be set or reset using 
*chattr <http://annys.eines.info/cgi-bin/man/man2html?1+chattr>*(1), 
although it can be displayed by *lsattr 
<http://annys.eines.info/cgi-bin/man/man2html?1+lsattr>*(1).

We have no idea why the system should have set the "I" bit on this 
symlink, uniquely among all symlinks ever created on the machine, but 
we're investigating that.  We have tentatively concluded that it has 
been cursed by the Giant Space Ants, but will no doubt revise our 
conclusions once we figure out what the hell use the "I" attribute might 
actually have for someone other than the Giant Space Ants.  The 
question, though,  is why it should then break swish-e.

Obviously, there are 10E8 workarounds for this but now it's a grudge 
match.  Any takers?

t.

-- 
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
Thomas R. Bruce (trb2@cornell.edu)
Director, Legal Information Institute
Cornell Law School
http://www.law.cornell.edu/

"We had a knob.  All we had to do was turn it."
                                 -- Les Paul
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+




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Received on Mon Jun 20 08:38:50 2005