2.6.38-stable review patch. If anyone has any objections, please let us know.
------------------ From: Tim Chen <[email protected]> commit c1530019e311c91d14b24d8e74d233152d806e45 upstream. During RCU walk in path_lookupat and path_openat, the rcu lookup frequently failed if looking up an absolute path, because when root directory was looked up, seq number was not properly set in nameidata. We dropped out of RCU walk in nameidata_drop_rcu due to mismatch in directory entry's seq number. We reverted to slow path walk that need to take references. With the following patch, I saw a 50% increase in an exim mail server benchmark throughput on a 4-socket Nehalem-EX system. Signed-off-by: Tim Chen <[email protected]> Reviewed-by: Andi Kleen <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/namei.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/namei.c +++ b/fs/namei.c @@ -712,6 +712,7 @@ static __always_inline void set_root_rcu do { seq = read_seqcount_begin(&fs->seq); nd->root = fs->root; + nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); } while (read_seqcount_retry(&fs->seq, seq)); } } _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
