-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Al Viro wrote: > On Sun, May 03, 2009 at 09:52:36AM +0100, Al Viro wrote: >> On Fri, May 01, 2009 at 12:11:12PM -0400, Jeff Mahoney wrote: >>> 2.6.30-rc3 introduced some sanity checks in the VFS code to avoid NFS >>> bugs by ensuring that lookup_one_len is always called under i_mutex. >>> >>> This patch expands the i_mutex locking to enclose lookup_one_len. This was >>> always required, but not not enforced in the reiserfs code since it >>> does locking around the xattr interactions with the xattr_sem. >>> >>> This is obvious enough, but it survived an overnight 50 thread ACL test. >> It's not enough, unfortunately ;-/ It deals with the warning, but it >> leaves an actual hole in there. >> >> Look: what happens if we mount it r/o without that directory and then >> remount r/w? We get dentry for privroot, hash it (negative at that point), >> then do actual mkdir, unlock root and modify the ->d_compare() of root >> to reject lookups on that sucker. Too late - in the meanwhile lookups >> might very well come and find privroot in dcache. >> >> BTW, the way ->d_compare() is done in there is rather dumb - >> if (q1 == &priv_root->d_name) >> return -ENOENT; >> ... >> would do just as well. Why don't we do that lookup *once* (on ->get_sb(), >> before anything can come and race with us), and then just keep negative >> dentry if the directory hadn't been around? And set d_compare() for root >> immediately after that lookup... >> >> I've applied your patch as-is, and unless you have objections to the >> variant above I'll do that as incremental. Comments? > > BTW, what in the name of everything unholy is ->xattr_root? Never > assigned a non-NULL value... Huh. I didn't see that still in there. That's an artifact of an earlier version of the code where I kept a reference to /.reiserfs_priv/xattrs. Then I decided that .reiserfs_priv was all I needed to cache (to avoid recursive i_mutex locking on the fs root) and dropped the caching of xattrs. Looks like it didn't get totally cleared out. - -Jeff -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkn+dEgACgkQLPWxlyuTD7J4/ACggM4bSYzp8zuS8KXf2WaFSpS4 458An1YCcTf4hYXjFXuU8ZS2eEWJCpaa =ZDpK -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe reiserfs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
