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authorJeff Layton <jlayton@redhat.com>2013-06-21 08:58:19 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2013-06-29 12:57:45 +0400
commit3999e49364193f7dbbba66e2be655fe91ba1fced (patch)
tree5971637ac3b15d5d72797d4050ee35216b9fede1 /fs/lockd
parent48f74186546cd5929397856eab209ebcb5692d11 (diff)
downloadlwn-3999e49364193f7dbbba66e2be655fe91ba1fced.tar.gz
lwn-3999e49364193f7dbbba66e2be655fe91ba1fced.zip
locks: add a new "lm_owner_key" lock operation
Currently, the hashing that the locking code uses to add these values to the blocked_hash is simply calculated using fl_owner field. That's valid in most cases except for server-side lockd, which validates the owner of a lock based on fl_owner and fl_pid. In the case where you have a small number of NFS clients doing a lot of locking between different processes, you could end up with all the blocked requests sitting in a very small number of hash buckets. Add a new lm_owner_key operation to the lock_manager_operations that will generate an unsigned long to use as the key in the hashtable. That function is only implemented for server-side lockd, and simply XORs the fl_owner and fl_pid. Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/lockd')
-rw-r--r--fs/lockd/svclock.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index a469098682c4..067778b0ccc9 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -744,8 +744,20 @@ static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
}
+/*
+ * Since NLM uses two "keys" for tracking locks, we need to hash them down
+ * to one for the blocked_hash. Here, we're just xor'ing the host address
+ * with the pid in order to create a key value for picking a hash bucket.
+ */
+static unsigned long
+nlmsvc_owner_key(struct file_lock *fl)
+{
+ return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
+}
+
const struct lock_manager_operations nlmsvc_lock_operations = {
.lm_compare_owner = nlmsvc_same_owner,
+ .lm_owner_key = nlmsvc_owner_key,
.lm_notify = nlmsvc_notify_blocked,
.lm_grant = nlmsvc_grant_deferred,
};