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locks: add a new "lm_owner_key" lock operation

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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>
This commit is contained in:
Jeff Layton
2013-06-21 08:58:19 -04:00
committed by Al Viro
parent 48f7418654
commit 3999e49364
4 changed files with 34 additions and 7 deletions
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12
fs/locks.c
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@@ -521,10 +521,18 @@ locks_delete_global_locks(struct file_lock *fl)
spin_unlock(&file_lock_lock);
}
static unsigned long
posix_owner_key(struct file_lock *fl)
{
if (fl->fl_lmops && fl->fl_lmops->lm_owner_key)
return fl->fl_lmops->lm_owner_key(fl);
return (unsigned long)fl->fl_owner;
}
static inline void
locks_insert_global_blocked(struct file_lock *waiter)
{
hash_add(blocked_hash, &waiter->fl_link, (unsigned long)waiter->fl_owner);
hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
}
static inline void
@@ -757,7 +765,7 @@ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
{
struct file_lock *fl;
hash_for_each_possible(blocked_hash, fl, fl_link, (unsigned long)block_fl->fl_owner) {
hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
if (posix_same_owner(fl, block_fl))
return fl->fl_next;
}