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>
This commit is contained in:
Родитель
48f7418654
Коммит
3999e49364
|
@ -349,6 +349,7 @@ fl_release_private: maybe no
|
|||
----------------------- lock_manager_operations ---------------------------
|
||||
prototypes:
|
||||
int (*lm_compare_owner)(struct file_lock *, struct file_lock *);
|
||||
unsigned long (*lm_owner_key)(struct file_lock *);
|
||||
void (*lm_notify)(struct file_lock *); /* unblock callback */
|
||||
int (*lm_grant)(struct file_lock *, struct file_lock *, int);
|
||||
void (*lm_break)(struct file_lock *); /* break_lease callback */
|
||||
|
@ -358,16 +359,21 @@ locking rules:
|
|||
|
||||
inode->i_lock file_lock_lock may block
|
||||
lm_compare_owner: yes[1] maybe no
|
||||
lm_owner_key yes[1] yes no
|
||||
lm_notify: yes yes no
|
||||
lm_grant: no no no
|
||||
lm_break: yes no no
|
||||
lm_change yes no no
|
||||
|
||||
[1]: ->lm_compare_owner is generally called with *an* inode->i_lock held. It
|
||||
may not be the i_lock of the inode for either file_lock being compared! This is
|
||||
the case with deadlock detection, since the code has to chase down the owners
|
||||
of locks that may be entirely unrelated to the one on which the lock is being
|
||||
acquired. When doing a search for deadlocks, the file_lock_lock is also held.
|
||||
[1]: ->lm_compare_owner and ->lm_owner_key are generally called with
|
||||
*an* inode->i_lock held. It may not be the i_lock of the inode
|
||||
associated with either file_lock argument! This is the case with deadlock
|
||||
detection, since the code has to chase down the owners of locks that may
|
||||
be entirely unrelated to the one on which the lock is being acquired.
|
||||
For deadlock detection however, the file_lock_lock is also held. The
|
||||
fact that these locks are held ensures that the file_locks do not
|
||||
disappear out from under you while doing the comparison or generating an
|
||||
owner key.
|
||||
|
||||
--------------------------- buffer_head -----------------------------------
|
||||
prototypes:
|
||||
|
|
|
@ -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,
|
||||
};
|
||||
|
|
12
fs/locks.c
12
fs/locks.c
|
@ -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;
|
||||
}
|
||||
|
|
|
@ -908,6 +908,7 @@ struct file_lock_operations {
|
|||
|
||||
struct lock_manager_operations {
|
||||
int (*lm_compare_owner)(struct file_lock *, struct file_lock *);
|
||||
unsigned long (*lm_owner_key)(struct file_lock *);
|
||||
void (*lm_notify)(struct file_lock *); /* unblock callback */
|
||||
int (*lm_grant)(struct file_lock *, struct file_lock *, int);
|
||||
void (*lm_break)(struct file_lock *);
|
||||
|
|
Загрузка…
Ссылка в новой задаче